BASIC OPERATION SKILLSsaharapcc.skills4success.co/spcc/opr/BASIC OPERATION SKILLS.pdf · BASIC OPERATION SKILLS 5 1. Basic Pump Principles Introduction Pumps have many uses in water

BASIC OPERATION SKILLS

1

BASIC OPERATION SKILLS

28 Aug – 01 Sep 2016 @ SAHARA - Jubail, Saudi Arabia.

By: Mr. Yahya Waqqad

BASIC OPERATION SKILLS

2

Table of Contents

1. BASIC PUMP OPERATIONS………………….….……. 004

2. BASIC COMPRESSORS OPERATIONS.…….……... 015

3. VALVES BASIC OPERATIONS…………………..…….. 027

4. BOILER BASIC OPERATIONS……………….….……… 043

5. HEAT EXCHANGER BASIC OPERATIONS………. 051

6. TANKS, VESSELS and COOLING TOWERS….... 056

7. DISTILLATION……………………………….……………… 079

8. BASIC INSTRUMENTATIONS………………..……… 100

BASIC OPERATION SKILLS

3

Objective

This course aims at introducing participants with the basic

personal and technical skills, as well as skills needed to accomplish

industrial strategy and all types of soft and hard technical skills.

The purpose of this guide also is to develop a learner’s skills in

understanding operational principals in industrial plants units and

developing operator’s skills.

The course will also highlight main activities relating to various

topics that can be worked on separately.

Introduction

By skills we are not merely referring to the technical skills of one's

profession, such as the ability at this moment to properly operate

your browser software on the Internet. We are actually referring to a

whole range of skills, from the very specific technical skills required

of life and one's work (interpersonal and psychological skills

demanded by life.)

BASIC OPERATION SKILLS

4

1-Basic Pump Operation:

BASIC OPERATION SKILLS

5

1. Basic Pump Principles

Introduction

Pumps have many uses in water and wastewater plants. There are many types

of pumps for a variety of uses. Some of these may be river pumps, chemical

feeder pumps, high service or pumps that pump water to the distribution

system, booster pumps in stations in the system, lagoon pumps for wash-water

disposal, and lab sample pumps, just to name a few. Mainly all water pumps

may be classified into two general categories; displacement pumps and

velocity pumps.

Displacement pumps use some sort of mechanical means (plungers, pistons,

gears or cams) for forcing specific volumes of water through the units.

Velocity pumps add velocity to water and convert the velocity into pressure

head which forces the water through pipes, valves, etc. Both types of pumps

raise the pressure on the inlet side to a higher pressure on the outlet side.

Hydraulics is the study of fluids at rest or in motion or under pressure. Water

flows in a water system when it is under a force that makes it move. The force

on a unit area of water is called pressure

Area In a water system, pressure is a measure of the height to which water

theoretically will rise in a standpipe open at the top. The pressure of (0.43

BASIC OPERATION SKILLS

6

lb/sq.in. PSI) the force per unit area at the bottom of a water column depends

directly, and only, on the height of the column. Thus, a 1 sq. ft. column 1ft.

high, with a total weight of 62.4 lbs. exerts a hydrostatic pressure of 0. 43 psi,

or in a 10 sq. ft. column = 4.3 psi.

The speed that water flows is called the velocity. Velocity is measured in miles

per hour or feet per second. The velocity of 1mph = 1.46 fps or 1fps = .68 mph

The quantity of water that flows through a pipe or ditch depends upon the

velocity and the cross sectional area of the flow at right angles to its direction.

Q = AV. 1 cfs = 7.48 gpm or gal/cu.ft.

Q = flow, A = area, V = velocity

Helpful Conversions

10# force on 1 sq. inch = 10 lbs/sq. in. or 10 psi

10 # force on ½ sq. inch = 10lbs/1/2sq. in. or 20 psi

Water weighs 62.4 lbs./ cu. ft. or 8.34 lbs/gal

2.31 ft. = 1psi.

.433 psi = 1 ft.

BASIC OPERATION SKILLS

7

1 cfs = 7.48 gpm

Q (flow rate) = AV = 7.48 gal/cu. ft.

Velocity of water = 449 gpm = 1 cfs Or .646 mgd = 1 cfs

Water plants generally acquire the water from the source (Raw) from lakes,

rivers, creeks, springs, or wells. Some plants are located where the source

water will flow to the plant by gravity flow, while other need to have a river

(raw) pump station to pump the water to the treatment plant. These pumps are

usually smaller in horsepower than the pumps providing flow to the

distribution system.

Water flows into the plant through flocculators, (that mix the chemicals), then

into settling basins, (which allows the dirt to settle out and for chlorine to have

contact time)- then into the filters and through the filters into a clear well

(storage area) - then pumped out of the clearwell and into the distribution

system by larger horsepower pumps and on to the customers. This entire

system is a balancing act - to maintain equality of flow and pump rates and

filter flow rates, through the entire system of treatment. Plants are designed by

engineers that calculate all of this information when the plant is being

designed, and will set up the plant to achieve this equality of water balance.

BASIC OPERATION SKILLS

8

For example river pumps may be a 125 hp and possibly a 200 hp to give a

variety of pumping options, while the high service or pumps that are pumping

water into the distribution system, may be a 500 or 600 horsepower pump. In

between these pump varieties, filters are adjusted to keep an even flow across

the basins and into the filters, and the outgoing pumps are keeping a balance

of water in the clear well or storage area, to continually keep up with demand

in town or the distribution system and/or to gain water in the distribution

storage tanks.

Pump components:

BASIC OPERATION SKILLS

9

• How Pumps Work

Answer

A centrifugal pump uses an impeller as the primary source for its pumping

action then the impeller is similar to a fan with a housing that has one small

intake and a larger output, which is simply an opening. The impeller is then

connected to a spinning rotor that must be moved, either with human or

mechanical power, in order to displace fluid, and for the impeller is inside a

housing that lets fluid escape to a discharge pipe, where the fluid is pushed

after being displaced by the impeller.

BASIC OPERATION SKILLS

10

• Head vs. Pressure

Head is the one term that most scares people when talking about how pumps work. After all when you talk about pumps you should be talking about pressure, everyone knows what pressure is. You put a pressure gauge on the outlet of a pump and you read the amount of pressure.

Figure 1 Measuring pressure with a pressure gauge.

You read 60 psi on the gauge of the pump in your house and you know everything is fine, everything should work properly. So what is it about head? Why do people even talk about it, and what does it have to do with pressure? So we are gonna get over this head

problem right now, and you'll never get the googly eyes when you here that term ever again. Assume that you have a pump that you can disconnect the

discharge pipe or tube and are able to extend it vertically. Head is the height at which a pump can raise water up, that's it, it's that simple.

BASIC OPERATION SKILLS

11

Figure 2 The meaning of head.

Connect a tube to the discharge of a pump and measure the water height, that the head of the pump. OK, so head is somehow linked to pressure, in what way? We will get to that later. For now let's agree to state that the more pressure the pump delivers the higher the head will be in the Figure 2. Let's say the head we measure in the above situation is 60 ft (18 m), what happens to the head measured if the level in the suction tank is higher. Will the head measured be higher or lower? If h2 is the head measured in Figure 2, will h3 be

Pump Maintenance and Repair: It has to mention that most of the pumps used are lubricated by oil and the

pump manufacturers do not export the pumps with oil installed in the bearing

frames. Oil is added just prior to the initialization of pump operation. Oil

should be replaced after the first 200 hours of operation or every 3 months

thereafter. The maintenance manual of the pump will provide authentic

BASIC OPERATION SKILLS

12

information on selection of oil type, its viscosity and grade. Use of correct oil

will smoothen the pump operation and will not allow the bearings to burn our

quickly. In the second part of the series of blogs aimed to share information on

pump maintenance, we analyze the critical step of ―Inspection‖ in Pump

Maintenance procedures.

Most maintenance departments invest a lot of time and efforts to refurbish the

pump, in case if it fails to perform due to technical inaccuracies. This

procedure forms an important part of the total pump maintenance process.

INSPECTION

Pump Maintenance is an art and science in itself. The pump industry is empowered with skilled veterans who possess prolific knowledge on Pump maintenance procedures and its intricacies. However, these veterans are fast approaching their retirement age and once they retire, there will be a dearth of experts having proficiency in pump maintenance that include proper pump installation, maintenance and operation. There are times when the pump stops functioning due to various factors.

The Inspection step begins by fully dismantling the entire pump unit and

examining each of the components. The major components that undergo

primary inspection are Pump Casing, Impeller, Stuffing Box Cover/Seal

Chamber, Shaft, Sleeve, Frame and Thrust Bearing Housing.

BASIC OPERATION SKILLS

13

Casing & Stuffing Box

Casing & Stuffing Box are prone to cracks, excessive wear and pitting, for

which they should be examined first. There should be immediate replacement

or repairing if there are cracks, localized wear or grooving in excess of 3.2mm

(0.125 inches), or pitting in excess of 3.2mm (0.125 inches) deep. The gasket

surface also needs to be inspected for any irregularities.

Impeller

Due to constant pounding, the impeller also undergoes wear and tear damages. The impeller should be replaced if following problems are detected.

The impeller should be also checked for grooving, pitting, and general wear.

Frame Adapter As a part of routine inspection steps, the frame adapter should also be

examined for cracks or corrosion. In frame adapter components like machine

bores, turned fits and gasket surface need to primarily checked. Components

should be clean and free from any dust or debris.

Shaft Sleeve

Shaft Sleeve should also be verified for any cracks or wear along the sleeve

outside diameter, especially if there is packed pump arrangement. Any wear

greater than 0.062 inches (0.002 mm) can be critical and the sleeve should be

replaced on instant basis. The inside diameter of the sleeve also needs to be

checked to ensure a proper seat on the shaft. Excess tolerance between the

BASIC OPERATION SKILLS

14

shaft and sleeve, especially when using mechanical seals, can lead to

premature seal failure.

The shaft sleeve should be inspected for straightness. In this case, the run-out

threshold limit should act as a deciding factor for further use of shaft sleeve.

Also, any shaft with undersized bearing fit should be replaced. There are many

repercussions of undersized bearing as they can lead to loose bearings,

increased loads, raised vibrations that can possibly cause premature seal,

bearing and coupling failure.

Thrust Bearing

Lastly, the thrust bearing needs to be examined for any corrosion or physical

damages such as cracks and pitting. Also, the bearing bore should conform to

the manufacturer designed tolerance levels. The Housing should be replaced if

there are any alterations or enlargement outside the tolerance range. A bearing

housing with inappropriate size fits can lead to early bearing failure

BASIC OPERATION SKILLS

15

2- BASIC COMPRESSORS OPERATION

Air Compressors: DEFINITION:

An air compressor is a device that converts power (usually from an electric motor, a diesel engine or a gasoline engine) into kinetic energy by compressing and pressurizing air, which, on command, can be released in quick bursts. An air compressor operates by converting mechanical energy into pneumatic energy via compression. The input energy could come from a drive motor, gasoline engine, or power takeoff.

The ordinary hand bellows used by early smelters and blacksmiths was a simple type of air compressor. It admitted air through large holes as it expanded. As the bellows were compressed, it expelled air through a small nozzle, thus increasing the pressure inside the bellows and the velocity of the expelled air.

Modern compressors use pistons, vanes, and other pumping mechanisms to draw air from the atmosphere, compress it, and discharge it into a receiver or pressure system.

Types of air compressor The most basic types of air compressors are designated as:

Positive displacement" and "non-positive displacement" (sometimes called "dynamic").

BASIC OPERATION SKILLS

16

The characteristic action of a positive displacement compressor is thus a distinct volumetric change-a literal displacement action by which successive volumes of air are confined within a closed chamber of fixed volume and the pressure is gradually increased by reducing the volume of the space.

The forces are static-that is, the pumping rate is essentially constant, given a fixed operating speed.

The principle is the same as the action of a piston/cylinder assembly in a simple hand pump. Applications

To supply high-pressure clean air to fill gas cylinders

To supply moderate-pressure clean air to a submerged surface supplied

diver

To supply moderate-pressure clean air for driving some office and school

building pneumatic HVAC control system valves

To supply a large amount of moderate-pressure air to power pneumatic

tools, such as jackhammers

For filling tires

To produce large volumes of moderate-pressure air for large-scale

industrial processes (such as oxidation for petroleum coking or cement

plant bag house purge systems).

Most air compressors either are reciprocating piston type, rotary vane or rotary

screw. Centrifugal compressors are common in very large applications.

BASIC OPERATION SKILLS

17

There are two main types of air compressor's pumps: oil-lubed and oil-less. The

oil-less system has more technical development, but is more expensive, louder

and lasts for less time than oil-lubed pumps. The oil-less system also delivers air

of better quality.

BASIC OPERATION SKILLS

18

BASIC OPERATION SKILLS

19

––––––

BASIC OPERATION SKILLS

20

Negative displacement

Negative-displacement air compressors include centrifugal compressors. These

use centrifugal force generated by a spinning impeller to accelerate and then

decelerate captured air, which pressurizes it.

Most air compressors either are reciprocating piston type, rotary vane or rotary

screw. Centrifugal compressors are common in very large applications. There

are two main types of air compressor's pumps: oil-lubed and oil-less. The oil-

less system has more technical development, but is more expensive, louder and

lasts for less time than oil-lubed pumps. The oil-less system also delivers air of

better quality.

Types of air compressor

According to the design and principle of operation

1. Reciprocating compressor 2. Rotary screw compressor 3. Turbo compressor

Positive displacement

Positive-displacement air compressors work by forcing air into a chamber

whose volume is decreased to compress the air. Piston-type air compressors use

this principle by pumping air into an air chamber through the use of the constant

motion of pistons. They use one-way valves to guide air into a chamber, where

the air is compressed.[1] Rotary screw compressors also use positive-

displacement compression by matching two helical screws that, when turned,

guide air into a chamber, whose volume is decreased as the screws turn. Vane

compressors use a slotted rotor with varied blade placement to guide air into a

chamber and compress the volume. A type of compressor that delivers a fixed

BASIC OPERATION SKILLS

21

volume of air at high pressures. Common types of positive displacement

compressors include piston compressors and rotary screw compressors.

Compression cycles

The object of all compressors is to raise the pressure of a gas with the minimum expenditure of energy...

There are four principle types of air compressors

Reciprocating compressors..Gas is compressed by positive displacement pistons in cylinders. Flow being controlled by valves.

Turbo-machinery.. Gas is driven by high speed impellers rotating in confined case

Rotary Machines... Gas is compressed by rotors provided with lobes, gears, vanes.. Near positive displacement

Ejectors.. Gas is moved using kinetic energy induced by high velocity jet through nozzles

When considering turbo machinery a number of different designations are used

Pumps - mainly for liquids Fans move gases against small pressure differences with

little change in density Blowers- move gases with some slight pressure

differences Compressors are used to move gases and provide

significant pressure increases

BASIC OPERATION SKILLS

22

Reciprocating compressors

Reciprocating compressors are often used with air reservoirs to provide compressed air for industrial and civil duties driving air tools etc. Reservoirs have to be used because reciprocating compressors provide a pulsating air delivery.. The figure below shows a hypothetical indicator diagram for a single stage -single acting reciprocating compressor.

a ->1... Air is drawn into the cylinder on the suction stroke 1 ->2... The suction valve is closed and air is compressed according to the law Pvn = c 2 ->b... The delivery valve opens and air is delivered under pressure b ->a... The delivery valve closes and the suction valve opens

The cycles shown is assumed to follow a series of equilibrium states and the gas is assumed to follow the equation of state . PV = RmT throughout.... The theoretical work done on the air per cycle is the area enclosed by [ a-1-2-b- a ] which equals

BASIC OPERATION SKILLS

23

ref..Poly-tropic Process If C is the rate at which the cycles are repeated then the rate at which energy is imparted to the air =

The ideal compression requiring the minimum amount of work is the perfect reversible isothermal compression process which obeys Boyle's law PV = c. This is represented by 1-3. The work saved ber cycle is [ 1-2-3-1 ]. If the compression was isothermal the work done per cycle would be [ a-1-3-b-a ] which is

The compressor isothermal efficiency is a measure of the departure from the ideal compression process and is defined as

Clearance Volume effect

A practical single stage compressor cylinder will have a small clearance at the end of the stroke. This clearance will have a significant effect on the work

BASIC OPERATION SKILLS

24

done per cycle. In operation the air in the clearance volume expands to 5 before any fresh air is drawn into the cylinder. The stroke is from 1 to 2 with a swept volume of (V2 - V1 ) but the suction is only from 5 to 2 giving a volume of (V2 - V5 ) taken into the cylinder on each stroke.

Effect of Clearance Volume

The volumetric efficiency obtained from the hypothetical indicator diagram is :

Assuming compression curve 2->3 and the expansion curve 4->5 follow the same law PVn = c then..

The volumetric ratio of compression (V2 /V 3 ) = the volumetric ratio of expansion (V5 /V 4 ) = r v. The volumetric efficiency =

That is

BASIC OPERATION SKILLS

25

It is clear that the smaller the clearance volume Vc the larger the volumetric efficiency will be. In practice is is possible to get the clearance volume down to 3 to 5% of the stroke.... When clearance is taken into account the work done per cycle =

The hypothetical power of a single stage compressor (kW working on c cycles /s)

The actual compressor diagrams differ from hypothetical diagrams because of valve opening and closing delays and component inertia. A typical actual indicator diagram is shown below.

A good approximation of the volumetric efficiency is indicated by the ratio of x to y measured at the atmospheric pressure line.. The actual performance of a reciprocating compressor used as pump is measured by the ratio.

Multi-stage

BASIC OPERATION SKILLS

26

When air at high pressure is required, multi-staged compression is more efficient than using a single stage compressor. Also single stage compressors delivering high pressures result in high gas temperatures which effect the lubrication and increase the risk of burning. It is required to compress air from P1 to P4. The diagram below shows the curve for single stage compression .a-b-c-k-h. The curve for ideal isothermal compression is also shown a-b-j-h. The area enclosed by the curves indicates the work done per cycle and it is clear that the work done in the ideal isothermal process is far less than that done in the single stage compression.

Assume a three stage compressor process is used. The air is compressed from P1 to P 2 (a -> c) and the air is transferred into a receiver and cooled to its original temperature (c -> d) and the air is then transferred from the receiver to a second cylinder and compressed to P3 (d -> e) . The air is then transferred to a second receiver and cooled back to its original temperature (e -> f) and transferred again to a third cylinder and compressed to P4 (f -> g). The overall process is represented by curve a-b-c-d-e-f-g-h. The cooling brings the process closer toward the

BASIC OPERATION SKILLS

27

3- VALVES BASIC OPERATIONS

Introduction:-

The control valve is composed of a valve with an externally

powered actuator. The control valve is designed specifically for

reliable continuous throttling with minimum backlash and packing

friction. The control valve is involved with the disposition of energy

in a process. It dispenses energy from the source, dissipated energy

that exists within the system, or distributes energy in the system in

one way or another.

The chemical and petroleum industries have many applications

requiring control of gases, liquids, or vapors processes. Many process

operation require regulation of such quantities as density and

composition, but by far the most important control parameter is flow

BASIC OPERATION SKILLS

28

rate. A regulation of flow rate emerges as the regulatory parameters

for reaction rate, temperature, composition, or a host of other fluid

properties. For this purposes the control valve is using as the process

control element.

Control Valve Types:-

The different types of control valves are classified by a

relationship between the valve stem position and the flow rate

through the valve. This control valve characteristic is assigned with

the assumptions that the stem position indicates the extent of the

valve opening and that the pressure difference is determined by the

valve alone. There are three basic types of control valves whose

relationship between stem position (as percentage of full range) and

the flow rate (as a percentage of maximum) is shown in the Picture.

Depends on the construction of the valve the valves are classified in

different names. Valves are classified in to two general types based

on how the valve closure member is moved: by linear motion or

rotary motion.

BASIC OPERATION SKILLS

29

The types of the valves as follows,

1. Globe valve

2. Butterfly valves

BASIC OPERATION SKILLS

30

3. Ball valves

4. Gate valves

BASIC OPERATION SKILLS

31

5. Knife edge valves

BASIC OPERATION SKILLS

32

Control Valve Parts

• The Valves has Two Main Parts

1. Body Assembly

Plug : Part that moves in and out of the seat ring to open and

close the valve. It can also be used to characterize the flow.

Bonnet: The valve component which houses the guides and

packing. It also seals one opening to the body.

BASIC OPERATION SKILLS

33

Bonnet Flange: Flange that attaches the bonnet to the body.

Guides — Bushings contained in the packing box which align

the plug with the seat ring.

Guides — Bushings contained in the packing box which align

the plug with the seat ring.

Packing — Material used to seal the valve from leaking around

the plug stem.

Packing Box — Internal bore of bonnet which contains guiding

and packing.

2. Actuator Assembly

Actuator — Device which develops sufficient thrust to open or

close the valve. Common designs include piston, diaphragm,

hydraulic, manual hand wheel and electro-hydraulic actuators.

Lifting Ring: Used for Lifting The Valve

BASIC OPERATION SKILLS

34

Adjusting Screw: Part used to compress the actuator spring.

Cylinder: Actuator part used for containing air pressure and

enclosing the piston.

Spring Button: The part that prevents movement of the

actuator spring and permits the adjusting screw to compress

the spring.

Spring: In piston actuators, the part which provides force for

fail-safe operation; in diaphragm actuators, the part that

provides force to counteract air pressure from the opposing

chamber.

Piston: Part used to separate two air chambers of piston

actuator.

Actuator Stem: Part used to connect the valve plug with the

piston actuator.

Yoke: A component which secures the actuator to the valve

body.

VALVES MAINTENANCE

ROUTINE MAINTENANCE

Maintenance Preparations

Before any kind of maintenance is performed on a valve, certain

preparations should be made. In addition to getting permission

from a supervisor and following specific plant procedures and

safety precautions, there are some basic preparations for valve

maintenance that are common to most facilities.

BASIC OPERATION SKILLS

35

Once a valve has been identified as requiring maintenance, either

through a routine inspection or because a problem has been

reported, a good first step is to check the valve manufacturer's

instruction manual. This step helps mechanics become familiar

with the valve's internal design specifications and with any special

maintenance instructions for the valve.

Part numbers and other information can also be found in the

manufacturer's instruction manual. A mechanic who knows that

replacement parts are needed can check the manual and order

them ahead of time so that they are available when maintenance

begins.

Before starling work on a valve, the mechanic should gather all

the necessary tools for the job, including hand tools, measuring

tools, cleaning tools, and any special tools suggested by the valve

manufacturer.

Each tool should be inspected carefully to make sure that it is in

good condition.

The work area must also be prepared. Any objects that might

obstruct maintenance or create a safety hazard should be

removed.

The valve must be taken out of service before it can be worked on.

For some valve maintenance jobs, the system that the valve is part

of must be taken out of service. In other cases, it may be possible

to bypass the valve and still keep the system in service.

In any case, the valve should be locked out and tagged in

accordance with facility procedures before any work is done on it.

BASIC OPERATION SKILLS

36

In addition, all pressure must be relieved from the valve, and all

fluid must be drained.

In the example, the mechanic has made all of the necessary

preparations, and the valve has been taken out of service. The

next step is to remove the valve from the system so that it can be

taken to a shop for repairs.

Valve removal procedures may differ, depending on how the valve

is attached to the system. In the example, the mechanic removes

a globe valve that is connected to the system by flanges.

The mechanic sprays each flange bolt with a penetrating lubricant.

Then he loosens the bolts on the side opposite from where he is

standing. This helps the mechanic avoid injury, because any

trapped pressure is released away from him.

Loosening the flange bolts may result in a small amount of fluid

leaking out from between the flanges. This is normal and it can

occur even when the pipeline has been drained.

When the bolts are loose, the mechanic takes them out one at a

time until only one bolt remains in the flanges at each end of the

valve. The two bolts that the mechanic leaves in place are

diagonally across from each other to provide maximum support.

Before the last two bolts are removed, the valve must be

supported by some other means. Personnel can be injured and

the seating surfaces of the valve and the flange can be damaged if

the valve crashes to the floor.

BASIC OPERATION SKILLS

37

If the valve is small another maintenance worker can hold the

valve in place while the last two bolts are removed. If the valve is

large, rigging or other types of support should be used.

After all of the flange bolts have been removed, the mechanic

removes the old flange gaskets. Any time a flange is taken apart,

the gaskets should be replaced.

The mechanic stores all removable parts, such as nuts and bolts,

together in a safe place so that they will be readily available when

they are needed for reinstallation.

Finally, with the valve properly supported, the mechanic carefully

lifts it out.

Adjusting and Replacing Packing

Like other plant components, valves are susceptible to problems.

One of the most common valve problems that maintenance

personnel encounter is excessive packing gland leakage.

In order to properly control valve leakage, maintenance personnel

should be familiar with the construction and use of packing.

The packing used in valves is typically a rope-like material made

from strong natural or synthetic fibers woven together with a

binder substance such as grease or wax. It is used to control

leakage around the valve's stem.

Packing is housed in an assembly called a packing gland. The

packing fits around the valve stem and fills a cavity called a

stuffing box. A device called a gland follower fits into the stuffing

box to compress the packing.

BASIC OPERATION SKILLS

38

A packing gland

Gland Follower: A valve part that holds packing in place and compresses it to prevent leakage through the stem and bonnet.

Valve Stem: A rod that connects the disc in a valve to the valve operator. The stem transmits the rotation of the operator to the disc.

Valve Stem

Stuffing Box: A cavity in which valve packing is held

BASIC OPERATION SKILLS

39

Packing Gland:

An assembly that contains and compresses packing

When the valve is fully assembled, the gland follower is lightened to exert pressure on the packing and hold the packing in place.

To adjust the packing in the example globe valve, the mechanic alternately tightens the gland nuts in a clockwise direction. This causes the gland follower to push against the packing and compress it.

To ensure even compression, the mechanic tightens each gland nut one flat at a time. A flat is equal to about one sixth of a full revolution.

A ruler can be used to make sure that packing is compressed evenly. This is done by measuring the distance from the top of the packing gland to the bottom of the gland follower. If the gland follower has been tightened correctly, the measurements should be the same at both gland bolts.

The packing should be compressed enough to prevent leakage, but not enough to prevent movement of the stem. After the packing is adjusted, the hand-wheel should be rotated open and closed to make sure that the stem can still move freely.

As the packing is adjusted over lime, the gland follower may eventually be lightened so much that it comes to rest on the bonnet.

If this occurs, the gland follower is bottomed, and it cannot be tightened any further. When this happens, the packing should be removed and replaced.

Worn or damaged packing must also be replaced.

Most valves are designed so that the packing can be replaced without having to disassemble the entire valve.

In some cases, it may be necessary to remove the valve's handwheel to gain access to the packing gland.

BASIC OPERATION SKILLS

40

With larger valves, the handwheel may not have to be removed when the valve is repacked.

Packing

A rope-like material typically made from strong natural or synthetic fiber woven together with a binder substance such as grease or wax; used to control leakage around a valve stem

Bonnet

A component attached to a valve body that supports the internal valve parts not supported by the valve body. The bonnet also provides housing for the disc when it is raised from the seating area.

The mechanic then sprays a penetrating lubricant on the bolts to make the gland nuts easier to remove.

If the nuts are rusty and will not move, the lubricant should be given a few minutes to work. Using excessive force may twist or break the bolts.

BASIC OPERATION SKILLS

41

Next, the mechanic turns the gland nuts counterclockwise to loosen and remove them. He stores all the parts together in a safe place.

After the gland nuts are removed, the mechanic raises the gland follower.

On the example valve, the gland follower cannot be taken off completely while the stem is still in place and surrounded by packing. Instead, it is held out of the way with a wire.

Once the gland follower is raised, the packing is accessible.

The mechanic uses a packing hook to remove the packing.

Keeping the sharp end of the packing hook clear of the valve stem, the mechanic removes the rings of packing one at a time.

This step is done carefully, because scratching the stem with the packing hook could cause liquid to leak past the packing when the valve is put back in service. A scratched valve stem could also damage the packing as the stem turns.

The number of rings, the packing type, and the packing design will all vary from valve to valve.

To ensure that the threads on the gland bolts and nuts are thoroughly cleaned, they should be gone over with a tap and die, or chased.

A tap and die are normally used to make new threads, but they can also be used for chasing, or cleaning, threads.

BASIC OPERATION SKILLS

42

When they are used for chasing, the die is threaded onto the bolt and the tap is threaded into the nut.

The tap and die must be correctly threaded on the bolt and nut threads. This avoids cross-threading, or cutting new threads, which will destroy the original threads.

The tap and die should be the same thread size and type as the bolt and nut.

To chase the threads on a bolt, the bolt is sprayed with a lubricant, and the die is threaded onto it. Then the die is moved back and forth to clean the threads.

BASIC OPERATION SKILLS

43

4-BOILER BASIC OPERATIONS

Definition

A boiler in basic terms is nothing more than a container in which heat

can be transferred from one media through the walls of the container

to water. Because thermal energy transport is directly related to

cross-sectional area, boilers are designed to contain the maximum

amount of surface area to volume ratio which will enable structural

rigidity and reasonably controllable operation.

With the ever increasing cost of materials and fuel, design engineers

are continuously challenged to produce higher efficiency boilers and

optimize the materials of construction whilst maintaining structural

rigidity.

BASIC OPERATION SKILLS

44

This trend in turn challenges the Water Treatment Company to

provide chemical treatment programs and technical back up service

which will allow the boiler plant to operate at maximum efficiency

while ensuring extended equipment operating life.

FIELDS OF APPLICATION

Laundries

Dyeing process, laboratories, ironing factories

Foodstuff and bottling processes

Rubber, polymer and synthetic processes

Community

Desalination plant

Chemical & petrochemical processes

Agriculture processes

Auxiliary services

BOILERS CLASSIFICATIONS :

Boiler systems are classified in a variety of ways. They can be

classified according to the end use, such as for heating, power

generation or process requirements. Or they can be classified

according to pressure, materials of construction, size tube contents

(for example, waterside or fireside), firing, heat source or circulation.

Boilers are also distinguished by their method of fabrication.

Accordingly, a boiler can be packaged or field erected. Sometimes

boilers are classified by their heat source. For example, they are often

referred to as oil-fired, gas-fired, coal-fired, or solid fuel –fired boilers.

Let us take a look at some typical types of boilers.

BASIC OPERATION SKILLS

45

1-Fire-tube boilers

In fire-tube boilers, combustion gases pass through the inside of the

tubes with water surrounding the outside of the tubes. The

advantages of a fire-tube boiler are its simple construction and less

rigid water treatment requirements.

The name "fire-tube" is very descriptive. The fire, or hot flue gases

from the burner, is channeled through tubes ('''Figure 2''') that are

surrounded by the fluid to be heated. The body of the boiler is the

pressure vessel and contains the fluid. In most cases, this fluid is

water that will be circulated for heating purposes or converted to

steam for process use.

Fire-tube boilers consist of a series of straight tubes that are housed

inside a water-filled outer shell.

BASIC OPERATION SKILLS

46

Every set of tubes that the flue gas travels through, before it makes a turn, is considered a "pass." So, a three-pass boiler will have three sets of tubes with the stack outlet located on the rear of the boiler. A four-pass boiler will have four sets and the stack outlet at the front.

2-Water-tube boilers

In a water-tube boiler ('''Figure 3'''), the water is inside the tubes and

combustion gases pass around the outside of the tubes. The

advantages of a water-tube boiler are a lower unit weight-per-pound

of steam generated, less time required to raise steam pressure, a

greater flexibility for responding to load changes, and a greater

ability to operate at high rates of steam generation

Figure 3

Three Common Boiler Safety Devices

BASIC OPERATION SKILLS

47

The safe and efficient operation of boilers and domestic water

heaters is essential for the smooth operation of most institutional

and commercial facilities. Improvements in designs and control

systems have made today’s units safer and more efficient than ever.

But good design practices alone do not ensure safety and efficiency.

In addition to good system designs, an ongoing inspection and

testing program carried out by a well-trained staff of technician’s

results in safe and efficient operations. Maintenance and engineering

managers who ignore any one of these elements run the risk of

compromising not only safety and efficiency but also the operation of

the equipment.

Safety Devices

All boilers and domestic water heaters have a range of built-in

devices to help ensure their safe operation. Like other components of

building mechanical systems, they require periodic maintenance to

ensure proper operation. Boiler operators and technicians should pay

close attention to three key safety devices to protect personnel,

equipment, and the facility:

Safety valves.

The safety valve is the most important safety device in a boiler or

domestic hot-water system. It is designed to relieve internal pressure

if a range of failures occur within the system. Although it is simple in

design and straightforward in operation, something as simple as

corrosion or restricted flow within the valve and its related piping can

affect its operation.

BASIC OPERATION SKILLS

48

Water-level control and low-water fuel cutoff.

Many systems combine these two separate boiler-safety functions

into one unit. They are designed to ensure the water level within a

boiler never falls below a predetermined amount. Should that

situation occur, the system is designed to shut down the boiler by

cutting off its fuel. Proper functioning requires operators to make

sure no build-up of sludge or scale exists within the system that

would interfere with its detection and operation.

Water-gauge glass.

Even with a functioning water-level-control system, operators must

verify the actual level of water in the system. Here, too, a build-up of

sludge and scale can give false level indications

Boiler Safety valve

BASIC OPERATION SKILLS

49

Boiler Start-up Checks

Immediately prior to boiler start-up perform the following:

Check that all ventilation and combustion air openings and louvers are clean and free of debris.

Verify boiler water level. Check that all stack dampers are open. Examine the boiler furnace for foreign material. Check the furnace and flue passes for fuel accumulation. Make sure the manual fuel valves are open.

Normal Boiler Start-up Procedure

After completing the start-up checks, close the operating switch and commence the normal starting sequence. The following list suggests a typical starting sequence:

operating controls closed interlocks (safety controls) closed start fans and purge the boiler purge requirements met energize igniter prove ignition flame within 10 seconds energize main fuel valve(s) establish and monitor main flame de-energize ignition, main flame proven release firing rate (combustion) control to demand normal operation

This starting sequence should be carefully observed to make sure that all steps are normal. Readings on flame signal strength meters (if fitted) should be observed and recorded in the boiler log.

A normal shutdown should be initiated by opening the manual burner switch. After the post purge has been completed, check the furnace for flame cutoff and make sure there is no residual flame in the

BASIC OPERATION SKILLS

50

furnace. Have fuel safety shutoff valves repaired or replaced if required.

Boiler operator Responsibilities

1. Maintain the Normal Operation Water Level (NOWL).

2. Never add water to a hot boiler when the water level cannot be

determined.

3. Test Safety and relief valves regularly in compliance with state

and local codes.

4. Follow standard operating procedures (SOP) and all instructions

from the Chief Engineer.

5. Maintain proper steam pressure or water temperature.

6. Routinely test the low water fuel cut-offs and feedwater pump

controls.

7. Routinely blow down the water column, water sight glass and

try cocks.

8. Maintain the burner according to manufacturer’s

recommendations.

9. Maintain proper fuel oil temperature and / or gas pressure.

10. Record fuel consumption regularly

11. Maintain optimum feedwater temperature.

12. Record make-up water consumption regularly.

13. Monitor and record stack temperature.

14. Maintain control of the boiler and auxiliary equipment.

15. Maintain the boiler room log.

16. Record all appropriate data and document any unusual condition

BASIC OPERATION SKILLS

51

5-HEAT EXCHANGERS BASIC OPERATIONS:

INTRODUCTION

A heat exchanger is a device that is used to transfer thermal energy (enthalpy)

between two or more fluids, between a solid surface and a fluid, or between

solid particulates and a fluid, at different temperatures and in thermal contact. In

heat exchangers, there are usually no external heat and work interactions.

Typical applications involve heating or cooling of a fluid stream of concern and

evaporation or condensation of single- or multi component fluid streams. In

other applications, the objective may be to recover or reject heat, or sterilize,

pasteurize, fractionate, distill, concentrate, crystallize, or con- trol a process

fluid. In a few heat exchangers, the fluids exchanging heat are in direct contact.

In most heat exchangers, heat transfer between fluids takes place through a

separating wall or into and out of a wall in a transient manner. In many heat

exchangers, the fluids are separated by a heat transfer surface, and ideally they

BASIC OPERATION SKILLS

52

do not mix or leak. Such exchangers are referred to as direct transfer type , o r

simply recuperators . I n con- trast, exchangers in which there is intermittent

heat exchange between the hot and cold fluids—via thermal energy storage and

release through the exchanger surface or matrix— are referred to as indirect

transfer type , o r simply regenerators . Such exchangers usually have fluid

leakage from one fluid stream to the other, due to pressure differences and

matrix rotation/valve switching. Common examples of heat exchangers are

shell-and- tube exchangers, automobile radiators, condensers, evaporators, air

preheaters, and cooling towers. If no phase change occurs in any of the fluids in

the exchanger, it is sometimes referred to as a sensible heat exchanger. There

could be internal thermal energy sources in the exchangers, such as in electric

heaters and nuclear fuel elements. Combustion and chemical reaction may take

place within the exchanger, such as in boilers, fired heaters, and fluidized-bed

exchangers. Mechanical devices may be used in some exchangers such as in

scraped surface exchangers, agitated vessels, and stirred tank reactors. Heat

transfer in the separating wall of a recuperator generally takes place by

BASIC OPERATION SKILLS

53

Classification of Heat Exchangers

A variety of heat exchangers are used in industry and in their products. The objective

of this chapter is to describe most of these heat exchangers in some detail using

classification schemes. Starting with a definition, heat exchangers are classified

according to transfer processes, number of fluids, degree of surface compactness,

construction features, flow arrangements, and heat transfer mechanisms. With a

detailed classification in each cate- gory, the terminology associated with a variety of

these exchangers is introduced and practical applications are outlined. A brief mention

is also made of the differences in design procedure for the various types of heat

exchangers

Maintaining and repairing heat exchanger tubes:

Tube plugging is probably the most frequently used maintenance and repair technique

for the tube side of an exchanger. This article provides information on how to locate

the positions of tube failures and discusses why it is important to know such

BASIC OPERATION SKILLS

54

information. It describes how to find out where the tubes failed and explains how to

analyze what caused failures, seen from the tube side. Descriptions of several kinds of

plugs and their uses and plugging techniques are included. Preparation of a plug map,

a key to tubeside maintenance, is also discussed.

Although tube ferruling and sleeving are less common, some of the requirements for

these maintenance techniques are so similar to those for plugging that this article

includes them.

LOCATING TUBE FAILURES

Tube failures may occur any time in the life of an exchanger. To get the longest, most-

effective exchanger service life you must find out where and why the tubes failed.

Two techniques that contribute to the failure analysis are 1) establishing the pattern of

the failures and their locations along the length of the tube, and 2) extracting the failed

tube for chemical analysis and metallurgical examination.

Maintenance workers are usually under pressure to return a shutdown unit to service

as quickly as possible. They are constantly aware of the cost of the lost production of

power or product. Therefore, they often take the quickest route to restore production,

rather than spending the time required to get to the root of the problem. This poor

practice provides no insight into changes that would prevent similar problems in a

replacement exchanger and may lead to an exchanger's early demise and replacement.

Here are some simple techniques for determining the axial position of tube failures.

Preliminary steps

Some preparation is required before you probe the tubes. The first step is to isolate

both sides of the exchanger from the process and utility streams. The preferred way is

to insert line blinds to and from the unit. Closing leak-tight valves may be acceptable

for some services where exposure to the fluids is not harmful. Where the hazards of

contact with process fluids is severe, use double block valves. Do not enter an

exchanger channel or bonnet unless the process lines are fitted with double block

BASIC OPERATION SKILLS

55

valves or the unit is off the line, and follow plant safety practices for entering closed

spaces.

You must do some initial cleaning of the tube interiors before you attempt to locate

leak positions. If the tube side stream is not hazardous or noxious, you may be able to

collect corrosion products by inserting an air nozzle into the individual tubes, blowing

through and collecting the material in a strainer at the other end. Chemical analysis of

the collected material in the laboratory may provide clues to the failure mechanism.

The bare minimum is to flush out the process fluids and water wash the tube side.

Blow-dry the tubes with clean, filtered dry air before examining the tube interiors

BASIC OPERATION SKILLS

56

6. TANKS, VESSELS, COOLING TOWERS

FRP tanks and vessels

FRP (Fibreglass Reinforced Plastics, also known as GRP, or Glass

Reinforced Plastics) is a modern composite material of construction

for chemical plant equipment like tanks and vessels

Chemical

equipment that range in size from less than a metre to 20 metres [1]

are

fabricated using FRP as material of construction.

FRP Chemical Equipments are manufactured mainly by Hand Lay-up

and filament winding processes. BS4994 still remains a key standard

for this class of items.

BASIC OPERATION SKILLS

57

Dual Laminate

Due to the corrosion resistant nature of FRP, the tank can be made

entirely from the composite, or a second liner can be used. In either

case, the inner liner is made using different material properties than

the structural portion (Hence the name dual (meaning two) and

laminate (a word commonly used for a layer of a composite material))

The liner, if made of FRP is usually resin rich and utilizes a different

type of glass, called "C-Glass", while the structural portion uses "E-

Glass". The thermoplastic liner is usually 2.3 mm thick (100 mils).

This thermoplastic liner is not considered to contribute mechanical

strength. The FRP liner is usually cured before winding or lay-up

continues, by using either a BPO/DMA system, or using an MEKP

catalyst with cobalt in the resin.

If the liner is not made of FRP, there are multiple choices for a

thermoplastic liner. The engineer will need to design the tank based

on the chemical corrosion requirement of the equipment. PP, PVC,

PTFE, ECTFE, ETFE, FEP, CPVC, PVDF are used as common

thermoplastic liners.

Due to FRP's weakness to buckling, but immense strength against

tensile forces and its resistance to corrosion, a hydrostatic tank is a

logical application for the composite. The tank is designed to

withstand the hydrostatic forces required by orienting the fibres in the

BASIC OPERATION SKILLS

58

tangential direction. This increases the hoop strength, making the

tanks anisotropically stronger than steel (pound per pound).

FRP which is constructed over the liner provides the structural

strength requirements to withstand design conditions such as internal

pressure or vacuum, hydrostatic loads, seismic loads (including fluid

sloshing), wind loads, regeneration hydrostatic loads, and even snow

loads.

Applications

FRP tanks and vessels designed as per BS 4994 are widely used in the

chemical industry in the following sectors: chlor-alkali manufacturers,

fertilizer, wood pulp and paper, metal extraction, refining,

electroplating, brine, vinegar, food processing, and in air pollution

control equipment, especially at municipal waste water treatment

plants and water treatment plants.

Tank Line Inspection

Large chemical and petroleum product storage tanks can be found at

chemical processing plants, refineries, and industrial locations.

BASIC OPERATION SKILLS

59

Types

FRP Vessels and Tanks are used in multiple applications, requiring a

strong, corrosion resistant environment.

Scrubbers

FRP Scrubbers are used for scrubbing fluids. In air pollution control

technology, scrubbers come in three varieties, Dry Media, Wet Media,

and Biological.

Dry Media

Dry media typically involved a dry, solid media (such as activated

carbon) suspended in the middle of the vessel on a system of beam

supports and grating. The media controls the concentration of a

pollutant in the incoming gas via adsorption and absorption.

BASIC OPERATION SKILLS

60

These vessels have several design constraints. They must be designed

for

Unloading and Reloading the media

Corrosive effects of the fluid to be treated

Internal and External Pressure

Environmental Loads

Support Loads for the grating and support system

Lifting and Installing the Vessel

Regenerating the media inside the vessel

Internal Stack supports for a dual bed construction

Redundancy for preventative maintenance

Demisting to remove liquids that degrade the dry media

Condensate removal, to remove any liquid that condenses

inside the vessel

Wet media

Wet media scrubbers typically douse the polluted fluid in a scrubbing

solution. These vessels must be designed to more stringent criteria.

The design constraints for wet media scrubbers typically include:

The corrosive effects of the polluted fluid and the scrubbing

solution.

The high pressures and loading of a spray system

BASIC OPERATION SKILLS

61

Aerodynamics of the internal media to ensure that there is no

bypass

Internal Support systems

Reservoir of scrubbing fluid for recirculation.

Internal and External Pressure

Environmental Loads

Lifting and Installing the vessel

Plumbing of the scrubbing fluid to the vessel

Draining to remove vessel sump fluids

In the case of a decarbonator, used in reverse osmosis systems to

limit the concentration of gases in the water, the air is the scrubbing

fluid and the sprayed liquid is the polluted stream. As the water is

sprayed out of the scrubber, the air strips the aqueous gasses out of

the water, to be treated in another vessel.

Biological

Biological scrubbers are structurally identical to the wet media

scrubbers, but vary in their design. The vessel is designed to be larger,

so the air moves slower through the vessel. The media is designed to

encourage biological growth, and the water that sprays through the

vessel is filled with nutrients to encourage bacteria to grow. In such

scrubbers, the bacteria scrub the pollutant. Also, instead of a single,

large support system (typically 10 feet depth of media for chemical

scrubbers), there are multiple stages of media support, that can change

BASIC OPERATION SKILLS

62

the design requirements of the vessel. (See biofilter for similar

technology that is usually performed outside of an FRP vessel.)

Tanks

A typical storage tank made of FRP has an inlet, an outlet, a vent, an

access port, a drain, and an overflow nozzle. However, there are other

features that can be included in the tank. Ladders on the outside allow

for easy access to the roof for loading. The vessel must be designed to

withstand the load of someone standing on these ladders, and even

withstand a person standing on the roof. Sloped bottoms allow for

easier draining. Level gauges allow someone to accurately read the

liquid level in the tank. The vessel must be resistant to the corrosive

nature of the fluid it contains. Typically, these vessels have a

secondary containment structure, in case the vessel bursts.

Size

The size of FRP Vessels is rarely limited by manufacturing

technology, but rather by economics. Tanks smaller than 7,500 liters

(2,000 gallons) are easily manufactured out of cheaper materials, such

as HDPE or PVC. Tanks larger than four meters are generally limited

by shipping constraints, and the economics suggest a concrete or steel

tank fabricated at the tank's location.

For chemical storage and air pollution control, the choice is to make

multiple tanks of smaller diameters. For example, one of the largest

odor control projects in California, the Orange County Sanitation

BASIC OPERATION SKILLS

63

District will utilize 24[2]

vessels total to treat 188,300 cfm (86,200

L/s) of odorous air, with a design of up to 50 ppm of hydrogen

sulfide.[3]

For an equivalent single vessel to perform as well as the 13

headworks trickling filters, the single vessel would have to be over 36

feet in diameter.[4]

This would be impractical due to the high shipping

requirements, internal supports, spray nozzles and other internals.

Plus this single vessel would not incorporate redundancy for

preventive maintenance.

Limitations

Typical FRP temperature limits are almost entirely based on the resin.

The thermoplastic resin will suffer from creep at elevated

temperatures and ultimately fail. However, new chemistry has

produced resins that claim to be able to achieve even higher

temperatures, which expand this field immensely. The typical

maximum is 110 degrees celsius.

Design standards

GRP Tanks fall under regulation of several groups.

Bs4994-87 is the British Standards Standard for FRP Tanks and

Vessels

ASME RTP-1 (Reinforced Thermoset Plastic Corrosion Resistant

Equipment) is the standard for FRP tanks and vessels held

within the United States under 15 psig and located partially or

BASIC OPERATION SKILLS

64

fully above ground. Typical design parameters and

specifications will require either compliance with ASME RTP-1

or accreditation from ASME.

ASTM 3299 which is only a product specification, governs the

filament winding process for tanks. It is not a design standard.

Tanks.

ASME RTP-1

In RTP-1 specifications, the primary concerns relate stress and strain,

such as hoop stress, axial stress, and breaking stress to the physical

properties of the material, such as Young's modulus (which may

require an anisotropic analysis due to the filament winding process).

These are related to the loads of the design, such as the internal

pressure and strain.

Storage Tanks and process vessels are used in chemical industries,

pharmaceutical industries, petroleum, gas off shore, oil & gas industries. These

are manufactured using premium quality raw material and possess a capacity to

withstand strong winds and high temperature.

BASIC OPERATION SKILLS

65

Storage tanks

Storage tanks are containers that hold liquids, compressed gases (gas tank) or

mediums used for the short- or long-term storage of heat or cold. The term can

be used for reservoirs (artificial lakes and ponds), and for manufactured

containers. The usage of the word tank for reservoirs is uncommon in American

English but is moderately common in British English. In other countries, the

term tends to refer only to artificial containers.

In the USA, storage tanks operate under no (or very little) pressure,

distinguishing them from pressure vessels. Storage tanks are often cylindrical in

shape, perpendicular to the ground with flat bottoms, and a fixed or floating

roof. There are usually many environmental regulations applied to the design

and operation of storage tanks, often depending on the nature of the fluid

contained within. Aboveground storage tanks (AST) differ from underground

(UST) storage tanks in the kinds of regulations that are applied.

Reservoirs can be covered, in which case they may be called covered or

underground storage tanks or reservoirs. Covered water tanks are common in

urban areas.

Storage tanks are available in many shapes: vertical and horizontal cylindrical;

open top and closed top; flat bottom, cone bottom, slope bottom and dish

BASIC OPERATION SKILLS

66

bottom. Large tanks tend to be vertical cylindrical, or to have rounded corners

transition from vertical side wall to bottom profile, to easier withstand hydraulic

hydrostatically induced pressure of contained liquid. Most container tanks for

handling liquids during transportation are designed to handle varying degrees of

pressure. A large storage tank is sometimes mounted on a lorry (truck) or on an

articulated lorry trailer, which is then called a tanker.

Storage Tanks Components

BASIC OPERATION SKILLS

67

Overfill Prevention

Bulk storage tank overfills are a common cause of product release and pollution

at tank farms, terminals and refineries. Some overfills are small and easily

contained, but the accumulation of product from repeated overfills or a single

large spill can cause significant soil and ground water contamination.

Throughout the bulk liquid storage industry, it is increasingly being viewed as

―good practice‖ to provide some form of overfill prevention on all hazardous

material storage tanks.

Independent Protection

It is widely agreed that independent high and high-high level alarms provide

adequate prevention measures. The height of the alarms on the tank will depend

BASIC OPERATION SKILLS

68

largely on company, local, state or federal regulations and are based on the

individual application, tank height and product transfer rate.

Overfill Prevention System Considerations:

Measurement of the level for overfill protection independent of other

gauging systems installed on the tank

High and high-high level alarms that can be seen or heard by the operator

controlling the tank transfer, such as audible sirens or horns and visual

lights

A device that, when activated, can automatically trigger a diversion plan

or shut down procedure for the process causing the alarm

More stringent regulations may be required for facilities

with:

Permeable ground materials that are inside the containment area

―Old‖ tanks that can be more susceptible to corrosion

Tanks near surface water, such as rivers, wetlands or lakes

Measuring Against Overfill

There are two defined methodologies to measure for overfill protection - single

point measurement and continuous measurement. Within each group there are a

number of technologies that can be utilized successfully. installation and

integration of third-party equipment from industry leading manufacturers into

Fuels Manager for remote monitoring and alarm in addition to the required local

alarms at the Crucial Process Value (CPV) point.

BASIC OPERATION SKILLS

69

Single point measurement devices tend to be simple and very reliable with a

low cost of ownership that can be installed at the high and/or high-high level.

Common technologies used are mechanical switches, electronic ‗tuning fork‘ or

optical sensors.

For continuous measurement, a standard level gauge is a common solution.

Any of the major gauging technologies can be used: float and tape (mechanical),

BASIC OPERATION SKILLS

70

servo, radar or magnetostrictive technologies. Your operators can check the

status of the gauge at any time and the gauge‘s operation can be monitored for

deviation against the primary level device. The main benefits - you know if

there is a problem with the gauge before it becomes an overfill problem and

your operators do not need to climb a tank to check the operation.

Software Alarms

Fuels Manager is capable of providing audible and visual software alarms from

every connected tank gauge. An integrated alarm toolbar and pop-up alarm

notification provide real-time visual and audible notification of alarms or

events. The toolbar also provides access to an active alarm summary, a historic

alarm log and an alarm log file browser that allows your operators to view and

print reports of alarms or events in detail.

Fuels Manager also tracks and prevents unauthorized modifications to the CPV.

Any product that requires seasonal CPV changes can be managed easily -

eliminating any errors when updating CPVs across

your facility.

Mechanical Level Switch Application

A major oil company applies risk assessment values to processes in their

terminals and sets minimum guidelines. After assessment, one facility in Latin

America, without any tank gauging or measurement of any kind; was required

to meet their minimum rating. In this case, each of the eight Mogas cone roof

tanks would require a level gauge and high level alarm switch. This switch

would have to be independent of the gauge and also follow API 2350 guidelines

for high level alarms.

Based on the tank types and measurement accuracy needed for the refined

products stored and distributed at the terminal, float and tape level gauges (2500

BASIC OPERATION SKILLS

71

ATG) and a mechanical (displacement) level switch were selected. The level

switch provided independent high-high measurement and testing. A lever could

be pulled to perform a routine manual test required by the site on a monthly

basis. The installation offered a non-obstructive approach to the day-to-day

operations of the facility and provided the most economic, reliable and user

friendly solution for this particular terminal and its employees. The terminal is

now in a position to upgrade its tank gauging system and company safety level

by installing transmitters with inputs for temperature as the need arises in the

future.

Cleaning

Cleaning of chemical storage systems can be a hazardous activity, and is

important for the long life of a system. Some good practice guidance on

cleaning of systems is given below:

• Depending on the nature and scale of cleaning, specialist contractors may be

required. This is particularly true for inside tanks which are classed as confined

spaces, thus special training and apparatus are required.

• Take great care when cleaning, access may be difficult and require specialist

equipment such as scaffolding or access vehicles. Cleaning may also be

awkward especially around pipes and connections.

• Ensure cleaning fluids used are compatible with the chemicals stored or

spilled.

• Always wash down the area affected by a spill as soon as it has been cleared.

Remember that the water used is likely to have

been contaminated.

BASIC OPERATION SKILLS

72

• Cleaned surfaces may be slip hazards whilst drying, particularly on

impermeable surfaces such as in bunds. Clearly mark these with warning

signage for other site operatives.

• As part of the cleaning programme include vents, meshes, grills, sumps etc.

These can collect debris and become blocked, or their performance affected so

should be cleared on a regular basis.

• Sand blasting or high pressure water jetting should only be undertaken from a

stable platform, and only when tanks are empty. This will help to avoid loss

from holes that may be punctured in the tank by point jetting.

• Great care should be taken when using steam or hot water for cleaning. After

cleaning, cooling steam can create a vacuum in systems if vents are left shut, are

blocked or do not have a vacuum break. Always ensure that a vacuum break

system is operated before commencing steam cleaning.

BASIC OPERATION SKILLS

73

BASIC OPERATION SKILLS

74

Pressure VESSELS:

A pressure vessel is a closed container designed to hold gases or liquids at a

pressure substantially different from the ambient pressure.

The pressure differential is dangerous, and fatal accidents have occurred in the

history of pressure vessel development and operation. Consequently, pressure

vessel design, manufacture, and operation are regulated by engineering

authorities backed by legislation. For these reasons, the definition of a pressure

vessel varies from country to country, but involves parameters such as

maximum safe operating pressure and temperature.

Shape of a pressure vessel

Pressure vessels can theoretically be almost any shape, but shapes made of

sections of spheres, cylinders, and cones are usually employed. A common

design is a cylinder with end caps called heads. Head shapes are frequently

either hemispherical or dished (torispherical). More complicated shapes have

BASIC OPERATION SKILLS

75

historically been much harder to analyze for safe operation and are usually far

more difficult to construct.

Theoretically, a spherical pressure vessel has approximately twice the strength

of a cylindrical pressure vessel with the same wall thickness.[2] However, a

spherical shape is difficult to manufacture, and therefore more expensive, so

most pressure vessels are cylindrical with 2:1 semi-elliptical heads or end caps

on each end. Smaller pressure vessels are assembled from a pipe and two

covers. For cylindrical vessels with a diameter up to 600 mm, it is possible to

use seamless pipe for the shell, thus avoiding many inspection and testing

issues. A disadvantage of these vessels is that greater breadths are more

expensive, so that for example the most economic shape of a 1,000 litres

(35 cu ft), 250 bars (3,600 psi) pressure vessel might be a breadth of 914.4

millimetres (36 in) and a width of 1,70 Safety features

Leak before burst

Leak before burst describes a pressure vessel designed such that a crack in the

vessel will grow through the wall, allowing the contained fluid to escape and

reducing the pressure, prior to growing so large as to cause fracture at the

operating pressure.

Many pressure vessel standards, including the ASME Boiler and Pressure

Vessel Code and the AIAA metallic pressure vessel standard, either require

pressure vessel designs to be leak before burst, or require pressure vessels to

meet more stringent requirements for fatigue and fracture if they are not shown

to be leak before burst.[6]

Safety valves

As the pressure vessel is designed to a pressure, there is typically a safety valve

or relief valve to ensure that this pressure is not exceeded in operation.

BASIC OPERATION SKILLS

76

Maintenance features

Pressure vessel closures are pressure retaining structures designed to provide

quick access to pipelines, pressure vessels, pig traps, filters and filtration

systems. Typically pressure vessel closures allow maintenance personnel.

Cooling towers

An industrial cooling tower is a heat rejection device which extracts waste heat

to the atmosphere through the cooling of a water stream to a lower temperature.

Cooling towers may either use the evaporation of water to remove process heat

and cool the working fluid to near the wet-bulb air temperature or, in the case of

closed circuit dry cooling towers, rely solely on air to cool the working fluid to

near the dry-bulb air temperature.

Common applications include cooling the circulating water used in oil

refineries, petrochemical and other chemical plants, thermal power stations and

HVAC systems for cooling buildings. The classification is based on the type of

air induction into the tower: the main types of cooling towers are natural draft

and induced draft cooling towers.

BASIC OPERATION SKILLS

77

Industrial Cooling Tower

Cooling towers vary in size from small roof-top units to very large hyperboloid

structures (as in the adjacent image) that can be up to 200 metres (660 ft) tall

and 100 metres (330 ft) in diameter, or rectangular structures that can be over 40

metres (130 ft) tall and 80 metres (260 ft) long. The hyperboloid cooling towers

are often associated with nuclear power plants,[1] although they are also used to

some extent in some large chemical and other industrial plants.

Although these large towers are very prominent, the vast majority of cooling

towers are much smaller, including many units installed on or near buildings to

discharge heat from air conditioning.

BASIC OPERATION SKILLS

78

BASIC OPERATION SKILLS

79

7. DISTILLATION

Distillation is a process of separating the component substances from a liquid mixture by selective vaporization and condensation. Distillation may result in essentially complete separation (nearly pure components), or it may be a partial separation that increases the concentration of selected components of the mixture. In either case the process exploits differences in the volatility of mixture's components. In industrial chemistry, distillation is a unit operation of practically universal importance, but it is a physical separation process and not a Large scale industrial distillation applications include both batch and continuous fractional, vacuum, azeotropic, extractive, and steam distillation. The most widely used industrial applications of continuous, steady-state fractional distillation are in petroleum refineries, petrochemical and chemical plants and natural gas processing plants.

Industrial distillation :

Typical industrial distillation towers.

BASIC OPERATION SKILLS

80

Section of an industrial distillation tower showing detail of trays with bubble caps Main article: Continuous distillation

To control and optimize such industrial distillation, a standardized laboratory method, ASTM D86, is established. This test method extends to the atmospheric distillation of petroleum products using a laboratory batch distillation unit to quantitatively determine the boiling range characteristics of petroleum products.

BASIC OPERATION SKILLS

81

Automatic Distillation Unit for the determination of the boiling range of petroleum products at atmospheric pressure

Industrial distillation[15][25] is typically performed in large, vertical cylindrical columns known as distillation towers or distillation columns with diameters ranging from about 65 centimeters to 16 meters and heights ranging from about 6 meters to 90 meters or more. When the process feed has a diverse composition, as in distilling crude oil, liquid outlets at intervals up the column allow for the withdrawal of different fractions or products having different boiling points or boiling ranges. The "lightest" products (those with the lowest boiling point) exit from the top of the columns and the "heaviest" products (those with the highest boiling point) exit from the bottom of the column and are often called the bottoms.

BASIC OPERATION SKILLS

82

Diagram of a typical industrial distillation tower

Industrial towers use reflux to achieve a more complete separation of products. Reflux refers to the portion of the condensed overhead liquid product from a distillation or fractionation tower that is returned to the upper part of the tower as shown in the schematic diagram of a typical, large-scale industrial distillation tower. Inside the tower, the downflowing reflux liquid provides cooling and condensation of the upflowing vapors thereby increasing the efficiency of the distillation tower. The more reflux that is provided for a given number of theoretical plates, the better the tower's separation of lower boiling materials from higher boiling materials. Alternatively, the more reflux that is provided for a given desired separation, the fewer the number of theoretical plates required. Chemical engineers must choose what combination of reflux rate

BASIC OPERATION SKILLS

83

and number of plates is both economically and physically feasible for the products purified in the distillation column

Commercially, distillation has many applications. For example:

In the fossil fuel industry distillation is a major class of operation in obtaining materials from crude oil for fuels and for chemical feedstock.

Distillation permits separation of air into its components — notably oxygen, nitrogen, and argon — for industrial use.

In the field of industrial chemistry, large ranges of crude liquid products of chemical synthesis are distilled to separate them, either from other products, or from impurities, or from untreated starting materials.

Distillation of fermented products produces distilled beverages with a high alcohol content, or separates out other fermentation products of commercial value.

An installation for distillation, especially of alcohol, is a distillery.

The distillation equipment is a still.

BASIC OPERATION SKILLS

84

Laboratory display of distillation: 1: A source of heat 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed control 13: Stirrer/heat plate 14: Heating (Oil/sand) bath 15: Stirring means e.g. (shown), boiling chips or mechanical stirrer 16: Cooling bath.

BASIC OPERATION SKILLS

85

Applications of distillation

The application of distillation can roughly be divided in four groups: laboratory scale, industrial distillation, distillation of herbs for perfumery and medicinals (herbal distillate), and food processing. The latter two are distinctively different from the former two in that in the processing of beverages, the distillation is not used as a true purification method but more to transfer all volatiles from the source materials to the distillate.

The main difference between laboratory scale distillation and industrial distillation is that laboratory scale distillation is often performed batch-wise, whereas industrial distillation often occurs continuously. In batch distillation, the composition of the source material, the vapors of the distilling compounds and the distillate change during the distillation. In batch distillation, a still is charged (supplied) with a batch of feed mixture, which is then separated into its component fractions which are collected sequentially from most volatile to less volatile, with the bottoms (remaining least or non-volatile fraction) removed at the end. The still can then be recharged and the process repeated.

In continuous distillation, the source materials, vapors, and distillate are kept at a constant composition by carefully replenishing the source material and removing fractions from both vapor and liquid in the system. This results in a better control of the separation process

BASIC OPERATION SKILLS

86

Determining Boiling Point from Vapor Pressure

Vapor pressure is determined by temperature, not by quantity of the liquid. Boiling occurs when the vapor pressure of a liquid equals the atmospheric pressure above that liquid. So, depending on the atmospheric pressure, a liquid can have many boiling points.

BASIC OPERATION SKILLS

87

Water for example, boils at 100oC...at 101.3kPa. (Common misconception is water always boils at 100oC) If we lower the atmospheric pressure, water does not need as much energy (temperature) to overcome the atmospheric pressure above the liquid. Therefore, the boiling point of water will be lower.

Example- Lowering the atmospheric pressure to 50kPa, will change waters boiling point to about 78oC

Vapor–liquid equilibrium

Vapor–liquid equilibrium (VLE) is a condition where a liquid and its vapor (gas phase) are in equilibrium with each other, a condition or state where the rate of evaporation (liquid changing to vapor) equals the rate of condensation (vapor changing to liquid) on a molecular level such that there is no net (overall) vapor–liquid inter-conversion. A substance at vapor–liquid equilibrium is generally referred to as a saturated fluid. For a pure chemical substance this implies that it is at its boiling point.[1] The notion of "saturated fluid" includes saturated liquid (about to vaporize), saturated liquid–vapor mixture, and saturated vapor (about to condense). Although in theory equilibrium takes forever to reach, such an equilibrium is practically reached in a relatively closed location if a liquid and its vapor are allowed to stand in contact with each other long enough with no interference or only gradual interference from the outside. This is not the case for intensive heat exchange or rapid pressure change, though

BASIC OPERATION SKILLS

88

BASIC OPERATION SKILLS

89

BASIC OPERATION SKILLS

90

INDUSTRIAL DISSTILLATION COLUMN INTERNALS

Such industries are the petroleum processing, petrochemical production, natural

gas processing, coal tar processing, brewing, liquified air separation, and

hydrocarbon solvents production and similar industries but it finds its widest

application in petroleum refineries. In such refineries, the crude oil feedstock is

BASIC OPERATION SKILLS

91

a complex, multicomponent mixture that must be separated, and yields of pure

chemical compounds are not expected, only groups of compounds within a

relatively small range of boiling points, also called fractions. That is the origin

of the name fractional distillation or fractionation. It is often not worthwhile

separating the components in these fractions any further based on product

requirements and economics.

Distillation is one of the most common and energy-intensive separation

processes. In a typical chemical plant, it accounts for about 40% of the total

energy consumption.[6]

Industrial distillation is typically performed in large,

vertical cylindrical columns (as shown in Figure 2) known as "distillation

towers" or "distillation columns" with diameters ranging from about 65

centimeters to 6 meters and heights ranging from about 6 meters to 60 meters or

more.

Figure 3: Chemical engineering schematic of a continuous fractionating column

BASIC OPERATION SKILLS

92

Figure 4: Chemical engineering schematic of typical bubble-cap trays in a

fractionating column

Industrial distillation towers are usually operated at a continuous steady state.

Unless disturbed by changes in feed, heat, ambient temperature, or condensing,

the amount of feed being added normally equals the amount of product being

removed.

The amount of heat entering the column from the reboiler and with the feed

must equal the amount heat removed by the overhead condenser and with the

products. The heat entering a distillation column is a crucial operating

parameter, addition of excess or insufficient heat to the column can lead to

foaming, weeping, entrainment, or flooding.

Figure 3 depicts an industrial fractionating column separating a feed stream into

one distillate fraction and one bottoms fraction. However, many industrial

BASIC OPERATION SKILLS

93

fractionating columns have outlets at intervals up the column so that multiple

products having different boiling ranges may be withdrawn from a column

distilling a multi-component feed stream. The "lightest" products with the

lowest boiling points exit from the top of the columns and the "heaviest"

products with the highest boiling points exit from the bottom.

Industrial fractionating columns use external reflux to achieve better separation

of products.[3][5]

Reflux refers to the portion of the condensed overhead liquid

product that returns to the upper part of the fractionating column as shown in

Figure 3.

Inside the column, the downflowing reflux liquid provides cooling and

condensation of upflowing vapors thereby increasing the efficacy of the

distillation tower. The more reflux and/or more trays provided, the better is the

tower's separation of lower boiling materials from higher boiling materials.

The design and operation of a fractionating column depends on the composition

of the feed and as well as the composition of the desired products. Given a

simple, binary component feed, analytical methods such as the McCabe–Thiele

method[5][7][8]

or the Fenske equation[5]

can be used. For a multi-component feed,

simulation models are used both for design, operation, and construction.

Bubble-cap "trays" or "plates" are one of the types of physical devices, which

are used to provide good contact between the upflowing vapor and the

downflowing liquid inside an industrial fractionating column. Such trays are

shown in Figures 4 and 5.

The efficiency of a tray or plate is typically lower than that of a theoretical

100% efficient equilibrium stage. Hence, a fractionating column almost always

needs more actual, physical plates than the required number of theoretical

vapor–liquid equilibrium stages.

BASIC OPERATION SKILLS

94

Figure 5: Section of fractionating tower of Figure 4 showing detail of a pair of trays with

bubble caps

In industrial uses, sometimes a packing material is used in the column instead of

trays, especially when low pressure drops across the column are required, as

when operating under vacuum. This packing material can either be random

dumped packing (1–3 in or 2.5–7.6 cm wide) such as Raschig rings or

structured sheet metal. Liquids tend to wet the surface of the packing, and the

vapors pass across this wetted surface, where mass transfer takes place.

Differently shaped packings have different surface areas and void space

between packings. Both of these factors affect packing performance.

Distillation Column Control

System Description

The process of distillation should be familiar to most readers. The basic concept

is that we can separate a mixture of two pure liquids with different boiling

points by heating the mixture to a temperature between their respective boiling

BASIC OPERATION SKILLS

95

points. For example, water boils at 100°C and ethanol boils at around 83°C at

atmospheric pressure. If we heat the mixture to say 92°C, the ethanol will boil

and be transformed into vapour (which is collected and condensed) while the

water will remain as a liquid. This phenomenon is usually quantified by the

relative volatility of the two components. A distillation column is used to make

this process more efficient. A schematic diagram of a distillation column is

shown below.

The distillation column itself is made up of a series of stacked plates. A liquid

feed containing the mixture of both liquids enters the column at one or more

points. The liquid flows over the plates, and vapour bubbles up through the

liquid via holes in the plates. As liquid travels down the column, vapour comes

in contact with it many times (due to the multiple plates). This is the critical

process in distillation columns. The liquid and vapour phases are brought into

contact because as one molecule of higher boiling material converts from

BASIC OPERATION SKILLS

96

vapour to liquid phase by energy release, another molecule of the low boiling

material utilises the free energy to convert from liquid to vapour phase.

The base of the distillation column contains a large volume of liquid, which is

mostly the liquid with higher boiling point (in our example, this would be

water). Out of the base flows some of this liquid, some of which is heated in the

reboiler and returned to the column. This is called the boilup, and is labeled V.

The remaining liquid is the bottom product, labeled B.

Some vapour escapes from the top of the column and is returned to a liquid state

in the condenser. Some of this liquid is returned to the column as reflux L, and

the remainder is the top product or distillate D.

Vapour and liquid phases on a given plate approach thermal, pressure and

composition equilibrium to an extent depending upon the efficiency of the plate

BASIC OPERATION SKILLS

97

BASIC OPERATION SKILLS

98

DISTILLATION COLOMN TROUBLESHOOTING

COMMON TROUBLES IN DISTILLATION COLOMN :

BASIC OPERATION SKILLS

99

BASIC OPERATION SKILLS

100

8. BASIC INSTRUMENTATIONS

Instrumentation is defined as the art and science of measurement and control of process variables within a production or manufacturing area.

An instrument is a device that measures a physical quantity such as flow, temperature, level, distance, angle, or pressure. Instruments may be as simple as direct reading thermometers or may be complex multi-variable process analyzers. Instruments are often part of a control system in refineries, factories, and vehicles. The control of processes is one of the main branches of applied instrumentation. Instrumentation can also refer to handheld devices that measure some desired variable. Diverse handheld instrumentation is common in laboratories, but can be found in the household as well. For example, a smoke detector is a common instrument found in most western homes.

Instruments attached to a control system may provide signals used to operate solenoids, valves, regulators, circuit breakers, or relays. These devices control a desired output variable, and provide either remote or automated control

BASIC OPERATION SKILLS

101

capabilities. These are often referred to as final control elements when controlled remotely or by a control system.

A Transmitter is a device that produces an output signal, often in the form of a 4–20 mA electrical current signal, although many other options using voltage, frequency, pressure, or Ethernet are possible. This signal can be used for informational purposes, or it can be sent to a PLC, DCS, SCADA system, Lab View or other type of computerized controller, where it can be interpreted into readable values and used to control other devices and processes in the system.

Control instrumentation plays a significant role in both gathering information from the field and changing the field parameters, and as such are a key part of control loops.

Definition

The Oxford English Dictionary says (as its last definition of Instrumentation[8]), "The design, construction, and provision of instruments for measurement, control, etc; the state of being equipped with or controlled by such instruments collectively." It notes that this use of the word originated in the U.S.A. in the early 20th century. More traditional uses of the word were associated with musical or surgical instruments. While the word is traditionally a noun, it is also used as an adjective (as instrumentation engineer, instrumentation amplifier and instrumentation system). Other dictionaries note that the word is most common in describing aeronautical, scientific or industrial instruments.

Measurement instruments have three traditional classes of use:[9]

Monitoring of processes and operations Control of processes and operations Experimental engineering analysis

BASIC OPERATION SKILLS

102

While these uses appear distinct, in practice they are less so. All measurements have the potential for decisions and control. A home owner may change a thermostat setting in response to a utility bill computed from meter readings.

A Piping and Instrumentation Diagram - P&ID, is a schematic illustration of functional relationship of piping, instrumentation and system equipment components

P&ID shows all of piping including the physical sequence of branches, reducers, valves, equipment, instrumentation and control interlocks.

The P&ID are used to operate the process system.

A P&ID should include:

Instrumentation and designations

Mechanical equipment with names and numbers All valves and their identifications Process piping, sizes and identification Miscellaneous - vents, drains, special fittings, sampling lines, reducers,

increasers and swaggers Permanent start-up and flush lines Flow directions Interconnections references Control inputs and outputs, interlocks Interfaces for class changes Seismic category Quality level Annunciation inputs Computer control system input Vendor and contractor interfaces Identification of components and subsystems delivered by others Intended physical sequence of the equipment

BASIC OPERATION SKILLS

103

Equipment rating or capacity

This figure depict a very small and simplified P&ID:

A P&ID should not include:

Instrument root valves control relays manual switches primary instrument tubing and valves pressure temperature and flow data elbow, tees and similar standard fittings extensive explanatory notes

BASIC OPERATION SKILLS

104

This Process Flow Diagram combines carefully selected information

from five detailed PID drawings to provide an overview of the entire plant. Colors were added to make the diagram easier to follow.

BASIC OPERATION SKILLS

105

Control

Control valve.

In addition to measuring field parameters, instrumentation is also responsible for providing the ability to modify some field parameters. That means the instrument is not only for measuring purposes, but also for changing and modification of the process system

Instrumentation engineering : is the engineering specialization focused on the principle and operation of measuring instruments that are used in design and

BASIC OPERATION SKILLS

106

configuration of automated systems in electrical, pneumatic domains etc. They typically work for industries with automated processes, such as chemical or manufacturing plants, with the goal of improving system productivity, reliability, safety, optimization, and stability. To control the parameters in a process or in a particular system, devices such as microprocessors, microcontrollers or PLCs are used, but their ultimate aim is to control the parameters of a system.

Instrumentation engineering is loosely defined because the required tasks are very domain dependent. An expert in the biomedical instrumentation of laboratory rats has very different concerns than the expert in rocket instrumentation. Common concerns of both are the selection of appropriate sensors based on size, weight, cost, reliability, accuracy, longevity, environmental robustness and frequency response. Some sensors are literally fired in artillery shells. Others sense thermonuclear explosions until destroyed. Invariably sensor data must be recorded, transmitted or displayed. Recording rates and capacities vary enormously. Transmission can be trivial or can be clandestine, encrypted and low-power in the presence of jamming. Displays can be trivially simple or can require consultation with human factors experts. Control system design varies from trivial to a separate specialty.

Instrumentation engineers are commonly responsible for integrating the sensors with the recorders, transmitters, displays or control systems. They may design or specify installation, wiring and signal conditioning. They may be responsible for calibration, testing and maintenance of the system.

In a research environment it is common for subject matter experts to have substantial instrumentation system expertise. An astronomer knows the structure of the universe and a great deal about telescopes - optics, pointing and cameras (or other sensing elements). That often includes the hard-won knowledge of the operational procedures that provide the best results. For example, an astronomer is often knowledgeable of techniques to minimize temperature gradients that cause air turbulence within the telescope