Marine High Pressure Steam Vertical Heating Exhaust Gas Boiler
The furnace and smoke side of boiler tubes absorb the heat produced by fired oil and transfer it to water, then the water will be evaporated into steam. Steam rise up and enter the vapor space because its specific gravity is reduced. The space left by steam will be made up by water with a heavier specific gravity. This process forms a natural steam-water circulation. When the water level becomes lower because water is evaporated into steam continuously, the feed water pump will feed water into boiler to keep the water level in the normal range. This process continues and steam will be produced continuously by absorbing the heat produced by fired oil to heat water.
Exhaust Gas Boiler
This series boiler is used for producing steam and hot water by absorbing the exhaust gas heat from diesel engine, as to improve the efficiency of diesel engine. So boiler’s operator should attach importance to the exhaust gas boiler’s management and also should familiar with the boiler’s structure and relevant system, should do the daily maintenance, and make the boiler’s yield benefit.
Brief instruction to boiler’s structure
The boiler is a natural circulation vertical exhaust gas boiler with smoke tube. It consists of boiler body, upper & lower smoke chamber; exhaust gas bypass equipment and so on.
The boiler body is formed the drum by shell, plain end and lower tube plate. Upper tube plate is inside the drum, the upper tube plate is welded with lower tube plate by steel tube, the upper tube plate is connected with plain end by smoke chamber plate. It is the circular steam space outside of the smoke chamber, the flue is in the above of upper tube plate, all smoke tubes are covered by boiler water, smoke box is in the under of lower tube plate, and the smoke box is connected with the exhaust gas bypass equipment. There are many hand-holes under the shell. In view of the convenience for checking & repairing boiler, manhole will be installed on the boiler.
The steam inside the boiler can be transferred to outside by main steam valve that is on boiler’s plain end. To insure boiler’s safety, one or two-safety valve which can discharge total steam produced by the boiler is installed on the plain end. Once boiler is running in the abnormal condition and result in super-high pressure, steam can be discharged from safety valve.
There are water level gauges on the above or under of steam-water dividing surface of the upper of drum, and water level gauge can indicate the water level all the time, it’s very helpful for boiler’s operator to do supervision. In additional, at the same height limit, there is one water level controller used for the transmission of water level, and also can send all kinds of electric sign to boiler’s controlling system according to the different water level. According to these different electric sign, controlling system can control the running of water pump, and send alarm sign.
The upper smoke box lies in the top of boiler. Exhaust gas from boiler body discharge to chimney pass by upper smoke box.
The lower part is the inlet smoke box for exhaust gas. The exhaust gas inlet nozzle will be connected with the main diesel engine on the lower smoke box. On the smoke box, there is an inspection door for overhauling.
The thermometer and barometer that lies on the upper & lower smoke box separately can indicate the temperature and resistance force of exhaust gas as to supervise the boiler’s running status.
In order to reduce the heat loss and insure the safety of boiler’s running, the outer surface of boiler body and upper & lower smoke box are covered with thick 60mm insulation.
◎.Oil Fired Boiler
Light oil or heavy oil is suitable for this boiler plant. The boiler can be used for heat supply, oil heating and daily life service.
Brief Introduction of Boiler Structure
The boiler body consists of boiler shell, furnace and pin tubes with an all welded type structure. The pin tube being assembled inside theΦ219 or Φ273 smoke tube separately, consists of closed-pitched columnar steel pins which are welded on the outside surface of a steel tube. The boiler furnace is a full water cooling furnace consisting of a cylindrical furnace and upper, lower end which increases heat transfer efficiently.
The convection-heating surface of boiler consists of smoke tubes and pin tubes. The high temperature smoke from furnace enters into smoke tubes, flush the internal surface of smoke tubes and the pin tubes at the same time, forming a high efficient convection-heat exchange tube group.
The setting & function of boiler accessories
a. Main steam valve — on the top of boiler, which can transfer the steam from boiler to steam main pipe.
b. Safety valve — on the top of boiler, which can discharge all the steam at full load when the boiler is over pressure.
c. Water level gauge and water level controller — on the steam-water interface, which is used for boiler water level indication and for the supervision by boiler operator. The water level controller is used to transmit the value of boiler water level. The control system will control the feeding water pump or do burner emergency stop according to the signals received respectively.
d. Feeding water stop valves and check valves — on the shell side, one set for main feed water and another set for standby purpose.
e. Scum valve — to be used for draining off the suspension of oil sludge.
f. Blow down valve — to be used for draining off the boiler’s deposition and dirt.
f. Gauge valves — on the top of boiler, to be used for connecting the instruments with steam inside the boiler.
g. Air vent valves — to be used for discharge the air inside the boiler when pressure is increased.
There are manholes and hand holes on the boiler shell in order to maintenance the inside parts of boiler conveniently.
In order to decrease the heat loss of boiler and to low the surface temperature of boiler, the outside surface of boiler should be packed with insulation material and covered with thin galvanized steel plate.
◎.Oil-Exhaust gas Boiler
This series boiler can produce steam only by firing oil or only by using the exhaust gas discharged from main engine or using them at same time. This boiler can be used for supply heat for auxiliary boiler of ship, for heating the fuel oil, service for daily life.
Brief Introduction to Boiler’s Structure
This series boiler is a kind of vertical oil-fired & exhaust gas composite boiler. The exhaust gas section absorbs gas afterheat discharged by main engine; the oil-fired section absorbs the heat by burning oil. The two sections lie in one cylindrical shell, share one steam-water space, but their smoke gas sides are isolated each other. So it means that this two sections can work separately also can work at the same time, and this two running way all can be automatically controlled by the control box.
This series boiler is a vertical cylindrical shell boiler, and mainly made of following parts:
1.The upper consists of two parts, one is for discharging exhaust gas, another is for discharging smoke gas of firing oil, the two parts are isolated each other
2.The middle part is boiler body. The boiler body is a cylindrical shell, on the top and the bottom of the body is upper tube plate and lower tube plate respectively. For the inside of shell, one side is heating surface of exhaust gas, another side is oil firing heating surface which consist of uptake and combustion chamber (furnace), the burner is connected with the frame of fire hole on the one side of furnace. It means the two heating surfaces are lies in the same shell and share one steam-water space, but their gas sides are isolated each other.
3.The lower part is the inlet smoke box for exhaust gas. The exhaust gas inlet nozzle will be connected with the main diesel engine on the lower smoke box. In order to measure the inlet gas’s temperature, there is thermometer on the nozzle. On the smoke box, there is an inspection door for overhauling. And a nozzle of wind pressure gauge is placed on the outlet of exhaust gas, coordinated to use for measuring the smoke gas resistance force of exhaust gas section with the wind pressure gauge on the upper smoke box.
This boiler has the advantage of taking small space of engine room, and is very convenient for central operating & controlling, because oil-fired section & exhaust gas section of boiler share one cylindrical shell.
In order to reduce the influence of accuracy of water level indicator & water level controller because of the ship’s inclination and wave, the boiler’s installation & orientation should be in a way that the boiler axis running through the water level indicator’s socket that is line with the ship’s centre-line or parallel to it.