My ppt vfd

APEX GROUP OF INSTITUTIONSA

PRESENTATIONON

Energy conservation in cement industry by use of Variable AC drives

Submitted to:-Mr. Dheeraj singh Submitted by:-NIKHIL NAMA

Contents

• Importance and purpose• Cement processing equipments• Functional working of an electric drive system• Applications• Slip power recovery• AC drives control method• Motor control through VFD• Reasons of using drives and case example

1. Energy Conservation and its Management has become a prime factor for the nation, society and individual due to high cost and non availability of energy.

Why Important?

2. Non awareness of latest technologies and methods, non-conventional energy sources and renewable energy sources and how to run the plant and equipment in an energy efficient manner.

Our Concern

1. Electrical motors when not selected properly can cause energy losses as high as 25% to 30%.

2. The motors designed in lower frame might not be properly selected and have lower margins when operated at abnormal operating conditions run with very low power factor and efficiency and result

in to high losses and consumption

The Purpose

1. Energy savings on most pump and fan applications. 2. Better process control and regulation. 3. Speeding up or slowing down a machine or process.4. Inherent power-factor correction5. Emergency bypass capability6. Protection from overload currents7. Safe Acceleration

Introduction to cement industry

1. Cement production is an energy intensive process2. The industry has been accused of wasting energy3. Demand for technologies driving higher energy efficiency in the

cement industry.

4. The deterioration of the basic process equipment – rotating kilns, raw and cement mills has reached a critical level of 85 – 90 %

5. The power-intensive wet process of cement manufacturing prevails6. High power consumption, defined not only by the process of

manufacturing but also technically obsolete equipment

7

Cement Processing Equipment• Crushers

– Powers of the drives typically vary from 500 kW to 3000 kW.– a very high start-up torque. – The drive is typically supported by a flywheel in the drive train.

• Separators

−2.8 – 3.8 kWh electric energy per tonne of raw material can be saved.

– Motors are often used in braking mode to guarantee fast and accurate speed control and also during stopping of the rotating separator.

8

• Conveyors– a cost-efficient alternative for transportation– not only for transportation of limestone but they are

also needed for transportation of stones, raw meals.

9

• Mills1. Tube Mill (or Ball Mill)

– Over 95% of the energy input to the machines ends up as heat. Only 1 to 2 % of the input power is used to create new material surface.

10

• Fans– used practically in all stages of the producing

cement and consume 30% of all electric energy– Typical motor powers vary between 20kW and

2000kW. – Fans can be propelled by a constant speed motor

with damper or vane or by a variable speed drive

11

Electric power consumption in a cement plant

Quarrying & preblending 6 kWh/tonne 5 %

Raw milling 28 kWh/tonne 24 %Blending 7 kWh/tonne 6 %Burning & cooling 25 kWh/tonne 22 %Finish milling 44 kWh/tonne 38 %Conveying,packing & loading

6 kWh/tonne 5 %

total 116 kWh/tonne

12

Fig- Block diagram of an electric drive system

APPLICATIONS OF VFD’S IN CEMENT PLANT

Induced Draft Fan for Cement Kiln

• The induced draft fan induces kiln air flow, which must be continuously controlled to match the process requirements. Because cement making is a thermal and a chemical process, both air volume and mass flow must be controlled.

• Advantage of using VFD for induced draft fan of Cement Kiln: • Maintenance of uniform working temperature, reduced fan noise

and saving of valuable floor space in the plant. • The ID fan power can be several thousand hp and using a drive to

control air flow can result in considerable energy savings • VFD optimises the fan RPM in such a manner that it precisely

matches the system operating conditions.

The input power decreases significantly as the speed is decreased to reduce flow rate.

The power of a fan is proportional to the cube of the mechanical angular frequency

Pfan ≈k Ω3

16

• To reduce the flow rate, the vane is partially closed .

• Speed can be controlled by varying the frequency, which controls the synchronous speed

• Therefore, in comparison with a vane to control the flow rate, a variable-speed fan can result in significant energy saving in cases where reduced flow rates are required for long periods of time.

Power consumption of fan

Cement Kiln Speed and Torque Control

Requirement of kiln drive are for

1.Motor current limit protection during starting stage.

2.High starting torque. A special design requirement is the starting torque.It is typically 250 percent of full load torque for the first three to five seconds before dropping to around 200 percent and gradually reducing further during the next 15 to 20 seconds at the end of which period the full speed is attained.

Typical starting characteristic for a kiln

Mills# In cement production, mills are process critical. Reliable and precise control has a high impact on production throughput and operating costs. Controlling them with VSD’s results in

#Energy savings: Grinding mills can consume more than 60 percent of the plant’s total electrical energy. Controlling them with VFD’s result in significant energy savings .

21

AC drives control methods

Scalar Control Method• The main task of scalar control is to form a phase

voltage based on preset values of amplitude and frequency

• Scalar control methods of an AC-motor can be generally realized with voltage-fed inverters, current-fed inverters and slip power recovery control.

• Usual speed control methods are U/ f = constant and U/f 2 = constant.

• The U/f 2 = constant method is often used in centrifugal pump and fan drives.

Generalised motor control through VFD

• Power circuit consists of a phase-controlled rectifier with • a single- or three-phase AC supply,LC filter, and inverter

• The frequency WC is the speed command variable

• Rectifier voltage command is generated directly from the • frequency signal through a U/f = constant gain constant

Slip power Recovery

In pumps and fans using constant speed motor with conventional control, variation in flow is achieved by means of throttling valve or damper. The Power consumed=P Q H/ (m xp)Where Q = Delivery of pump in m3/sec H = pressure head (m) m = motor efficiency p = pump efficiency

Variable Speed Drives

Q-H characteristics of pump

0

100

200

300

400

500

600

0 1 2 3 4 5 6

Discharge(Q) in m3/sec

Pressu

re (

H)

in m

m o

f w

ate

r

H

Hr1

Hr2

Q-H Curve with variable speed motor

0

100

200

300

400

500

600

0 1 2 3 4 5 6

Discharge(Q) in m3/sec

Pre

ssu

re (

H)

in m

m o

f w

ate

r

H1

H2

Hr

26

Reasons for variable AC DRIVES in cement industry

1. Soft starting and reversing of motor

2. Accurate speed Regulation

3. Dynamic torque Regulation

4. High power factor

5. Regenerative braking

6. Flying start

7. Considerable maintenance savings and increased productivity.

Case example

• A Mexican cement plant replaced the existing damper fan control of two 735 kW fixed speed ID fans with ABB AC drives

• Revenue increased by about USD 900,000 through improved productivity

• Maintenance was reduced by about 97%

Energy saving About 5,300 MWh/year

CO2 reduction 2,650 tonnes/year

Segment and application Cement, fans

© ABB Group April 11, 2023 | Slide 27

Now queries???