Types of Boilers

TYPES OF BOILERS

Babcock & Wilcox - Water tube steam boiler

A water tube boiler consisting in its simplest form of a horizontal drum from which is suspended a pair of headers carrying between them an inclined bank of straight tubes. In marine boilers of this type are the water-tubes lying, but slightly inclining towards the boiler front. The tube ends are connected to a number of vertically collecting boxes with almost quadratic cross section. These are made of sheet metal and are laterally wave shaped. The tubes can be cleaned or replaced through hand-holes that are place ahead of each tube. The collecting boxes, on the boilers front side, are in the down-end connected to a mud disposal box with a blow down valve. The upper end of the collecting boxes by means of elbowed pipes connected to the lying steam drum. The collecting boxes at the water tubes rear side are closed at both ends. From the upper ends are tubes connected to the steam drum above the water level. At normal conditions the water level will be little below the mid-point of the steam drum.

Babcock Wanson marine steam generator

The Vaporax steam generator Because of the innovative design, the rise to working pressure can take place in 3 minutes starting from a cold boiler in stand-by. This characteristic as well as the low volume of water reduces the thermal losses and therefore helps to keep the operating costs low. I guess that a tube with total evaporation of the feed water is very exposed to deposits. Maybe someone could enlighten me on this.

The combustion air is introduced into the boiler through a preheater which recovers the residual heat. It is then injected into the burner. The flame and the hot gases heat a monotubular coil of varying diameter via three gas passes. Feed water is pumped through the coil, which, once heated, is transformed gradually into steam. A separator ensures the dryness of steam if required by the process is always sent to the point of use. The feed-water flow is directly proportional to the desired steam output.

Carlsund fire tube steam boiler

Old marine boiler from 1845

Cochran donkey boiler

The boiler has a dome-shaped furnace top that forms the bottom of the boiler itself. It has a neck on the front through which the boiler is fired and there is another on the rear part of the top that leads to a higher located combustion chamber. The combustion chambers backside is covered with brickwork and from its front-side a horizontal bank of flue-tubes leads to the smoke box on the front side of the boiler. The Cochran donkey boiler, or auxiliary boiler, was used in harbor when the main boilers were not needed for the propulsion of the ship and consequently the steam demand was low.

Cochran Marine Thermax boiler

A modern version of the Cochran steam boiler.

Two of those were installed in the paddle steamer Waverley in August 2000.

Composite marine steam boiler The composite marine steam boiler is a combination of an oil-fired steam boiler and an exhaust gas economizer. When the diesel engine is at full load the fuel oil burner only starts if the steam demand exceeds the steam production achieved from the diesel engines exhaust gases.

Most common composite boilers nowadays have separated sections for the diesel engines exhaust gases and the flue gases from the fuel oil burners. The economizer part also works as a silencer for the diesel engine, but often an additional silencer is required.

Eckrohr Steam Boilers

Eckrohr-Boiler (Corner Tube Boiler) is a boiler for all kinds of fuel. Originally it got its name because it has downcomers in the four corners. It is a natural water circulation single drum boiler and it needs no circulation pump. Downcomers, headers and waterwalls are welded together to a gas-tight tube cage. The Eck-rohr-Boiler is self-supporting and needs no supporting structure. It stands on its own downcomers.

Due to the cage structure with downcomers, headers and overhead pipes the Eckrohr-Boiler is earthquake safe (more than 550 boilers installed in Japan, many of them for municipal waste).

Gunboat fire-tube marine steam boiler

The so-called "gunboat boiler" was provided with tubes in the extension of the furnace. A cylindrical boiler, of relatively small diameter and extended length, provided with a furnaces in a fire-tube leading to a bank of flue-tubes through the water drum to the smoke-box at the boilers backside.

The gunboat boilers were, as the name indicates, used in small navy ships such as gunboats, escort vessels and corvettes where the width and the height were limited. Besides, the limited height of the boiler made it possible to have it installed entirely below the sea water line and hence protected from direct hits.

The gunboat boilers also existed with two furnaces.

Hybrid boiler? All I know about it is that it was manufactured at the Lindholmens shipyard in Gothenburg Sweden. The shipyard doesn't exist anymore so it's not possible to get any information there.

A Scotch Yarrow hybrid?

It looks like a combination between a Scotch marine boiler with three furnaces and a Yarrow boiler?

LaMont steam boiler

The LaMont boiler is a semi-flash boiler in which the feedwater is supplied by means of a pump to the ends of long closely spaced tubes of small diameter. The tubes end in a separating drum where the emulsion of steam and water separates. The boiler requires a powerful pump for the forced circulation of the boiler water.

The LaMont boilers forced water circulation and the tubes of small diameter gives enormous freedom as far as the design of the heating surfaces concern.

Normand water-tube marine steam boiler

A marine water-tube boiler employing an upper steam drum connected by banks of inclined tubes to two lower waterdrums. All the tubes discharge below the water level in the upper drum. Larges downcomers are mounted outside the furnace. The furnace is placed between the lower waterdrums and the flue gases flows between the tubes on both sides of the steam drum. The main difference between the Normand boiler and the Yarrow boiler is that the external downcomers.

Nuclear reactor and steam generators

Schematic diagram of a pressurized water nuclear boiler

A. Feedwater pump B. Feedwater line C. Steamgenerator

Radiation shielding is not needed on this secondary cycle. D. Downcomer

The water is directed downward and flows along a wrapper sheet. E. Riser

The water is directed upwards inside the wrapper sheet to flow along the steam generator tubes.

F. SteamSeparators The steam separator removes the remaining moisture from the outgoing steam.

G. MoistureSeparators Moisture separator. Removes water droplets and moisture from the steam.

H. ReactorCoolantPump Part of the Primary Loop

I. PrimaryLoop The function of the primary loop is to transfer the heat from the reactor to the steam generator. The primary loop is a Reactor Cooling System.

J. Reliefvalve Releses the pressure in case of overpressure.

K. Spryer Cooling down the pressurizer and reduces the pressure.

L. Pressurizer Pressurizes the water to prevent it from boiling.

M. Heater Heating the Pressurizer and increases the pressure.

N. Coolant Pressurized water.

O. FuelRods Fissionable material, Uranium.

P. Reactorvessel The reactor vessel that contains the nuclear fuel is the central component of the reactor coolant system. All internal surfaces of the vessel are clad with stainless steel to avoid corrosion. The reactor vessel is radiation shielded.

Q. Controlrods Absorb neutrons and slow down the reaction. Boron or Cadmium rods

R. Controlrodsdrivemechanism Adjusting the energy output of the reactor.

S. Steamoutlet Steam to turbines and other consumers.

Schulz water tube marine steam boiler

The Schulz boiler was used in the German navy

The construction is rather like the Thornycroft boiler. It has three water drums at the bottom; connected to the steam drum by means of bended tubes that discharge below the water level in the steam drum. The water drums are interconnected by means of horizontal tubes behind the boiler. The tubes between the steam drum and the center waterdrum function as downcomers. The outmost tube-rows and the center tube-row in each bank of tubes are partly welded together to form water walls. This will delay the flue gas in the boiler and improve the efficiency.

Scotch fire tube marine steam boiler

The single-ended return tube Scotch boiler consists of a cylindrical boiler shell of large diameter and short length, provided with two or more furnaces in corrugated fire-tubes. Each furnace ends in a combustion chamber, surrounded by water. The gases pass through a bank of flue-tubes from the combustion chamber to the smoke-box at the boiler front

The Scotch fire tube boiler contained a large quantity of water, about six times more than a water-tube boiler, and was therefore slow to steam up and to change the output capacity. Due to the boilers stiff construction it required also a long steaming up period to avoid leaks caused by thermal expansion of the material.

The double-ended Scotch fire-tube steam boiler

These types of boilers were normally used in ships with many boilers. Space was saved even though two stokeholes were required. Normally a pair of furnaces shared one combustion chamber. When the furnace door was open, cold air could hit the combustion chambers opposite wall and cause tube leakage. To prevent that a high baffle of firebrick was installed in the middle of the combustion chamber. Twenty-four double-ended boilers with three furnaces at each end and five single-ended boilers with three furnaces were installed onboard R.M.S. Titanic. Electrically operated stoking indicators were used in the stokeholds to prevent that opposite furnace doors were open at the same time. These indicators also helped to minimize the total number of simultaneously open furnace doors.

Stirling water tube steam boiler

A water tube boiler in which two, or more, upper drums and one lower drum are connected by highly inclined banks of water tubes curved so as to enter the drums radially, the upper drums being also connected by horizontal steam and water tubes. This kind of boiler has never, as far as I know, been used on ships.

Sunrod steam boilers

A waterwall made of panel tubes makes a gas-tight furnace from which the flue gases pass through the Sunrod pin tube elements to the smoke-box on the top of the boiler. You may consider the Sunrod boiler as a hybrid between fire tube boilers and water tube boilers. The waterwall consists of water tubes, but the Sunrod element is a flue tube with a water-tube inside. Svenska Maskinverken originally designed the Sunrod boiler but nowadays several boilermakers manufacture them.

Thornycroft water tube marine steam boiler

The Thornycroft boiler has an upper steamdrum and a lower waterdrum connected together by banks of tubes. The tubes are very curved and all of them discharge into the steamdrum above the water level. In later models some of the tubes discharge below the level. A down comer between the steam drum and the water drum is located behind the boiler. The flue gas pass through the banks of tubes and violent circulation arise in the tubes and the evaporated steam conveys water to the steam drum. This water heavy circulation keeps the tubes free from deposits. These boilers have an upward narrowing

shape and call for -- especially if they are placed side by side -- a larger space than other square-shaped boilers.

This boiler has two lower drums. Huge downcomers are installed between the steam drum and the water drums.

Thornyeroft water tube boiler with two water drums. Notice that the fire in the furnace doesn't heats the downcomers.

Combustion Engineering water tube marine steam boiler V2M8 with regenerative air preheater

A Vertical Boiler whose major design features are the gastight waterwall furnace and the vertical in-line inverted U-loop superheater. The boiler shown is top-fired with resulting improved gas distribution over the entire superheater furnace. Both the main-bank tubes and superheater elements are in-line for improved tube cleaning. Normally, soot-blowing equipment includes retractable blowers in the superheater and rotary blowers in the main bank and economizer. The combustion air preheater, on the top of the boiler, heats the inlet combustion air to the burners by means of the flue cases and improves the efficiency of the boiler.

Water and steam flow diagram

Blue: the downcomers lead the water from the steam drum to the water drum and the waterwalls headers. Red and blue: the evaporation tubes and the water walls lead the water and steam emulsion back to the steam drum. Red: the steam passes through the superheater before it leaves the boiler for the consumers.

One large V2M8 boiler is installed in a ship at a shipyard and one other boiler is still suspended in the crane-hook.

When the boilers are placed and secured then the engine room will be built around them.

Combustion Engineering water tube marine steam boiler V2M9 with regenerative air preheater

The most outstanding feature of the V2M9 is the combustion. The boiler is a vertical two-drum dropped-furnace boiler. A burner is located at each of the four corners of the furnace and the burners are aligned to be tangential to a circle in the center of the furnace. This arrangement gives a rotary motion to the combustion gases within the furnace, with improved turbulence and air/fuel mixing. This lengthens the fuel-particle residence time in the furnace and allows combustion to be completed before the gases pass into the convection generating bank and superheaters.

Water and steam flow diagram

Blue: the downcomers lead the water from the steam drum to the water drum and the water walls headers. Red and blue: the evaporation tubes and the waterwalls lead the water and steam emulsion back to the steam drum. Red: the steam passes through the superheater before it leaves the boiler for the consumers.

Water tube boiler with two drums

A. Smoke uptake B. Economizer

A heat exchanger that transfers heat from Boiler Flue Gases to Boiler Feedwater. C. SteamOutlet

Saturated steam from the SteamDrum to the Superheater D. Cyclone

A device inside the drum that is used to prevent water and solids from passing over with the steamoutlet.

E. Stay tube for superheater

F. Stays for superheater tubes

G. Superheated steam outlet H. Superheater

A bank of tubes, in the exhaust gas duct after the boiler, used to heat the steam above the saturation temperature.

I. Superheater Headers Distribution and collecting boxes for the superheater tubes.

J. WaterDrum K. Burner L. Waterwall Header

Distribution box for waterwall and downcomers. M. Foting N. Waterwall

Tubes welded together to form a wall. O. Waterwall Header

Distribution box for waterwall and downcomers. P. Back side waterwall Q. Boiler hood R. Waterwall Header

Collecting box for waterwall and risers. S. Riser

Tubes in which steam is generated due to high convection or radiant heat. The water-steam emulsion rises in these tubes toward the steamdrum.

T. Downcomer A tube through which water flows downward. These tubes are normally not heated, and the boiler water flows through them to supply the generating tubes.

U. SteamDrum Separates the steam from the water.

V. Economizer Header Distribution box for the economizer tubes.

Yarrow water tube marine steam boiler

A marine water tube boiler employing an upper steam drum connected by banks of inclined tubes to two lower water drums. All the tubes discharge below the water level in the upper drum. The outer tubes function as down comer and the inner tubs function as evaporating tubes. This causes violent circulation of the water and separate downcomers are not needed. The furnace is placed between the lower drums and the flue gases flows between the tubes on both sides of the steam drum.

The Yarrow boiler was widely used in the navy of many countries. Later models had bended tubes to improve the elasticity of the construction.

A small Yarrow boiler used in a navy launch. These longboats are used to transport passengers and luggage to th