Steam boilers use a contained heat system to generate steam. The steam travels through pipes in the building’s walls where they emerge at radiators in heating systems. The radiators warm from the steam’s heat. As the steam gives off its heat, it condenses back to liquid water and returns to the tank. A boiler system of this type that does not allow outside water sources is a closed system and is highly efficient for using all the condensed water. An open network may be required in operations where the steam or water gets contaminated in such a way that it cannot return to the boiler for reuse.
To guarantee the successful and efficient shell boiler operation, the user must:
1)Know the conditions, environment, and demand characteristics of the plant, and accurately specify these conditions to the boiler manufacturer.
2)Provide a boiler house layout and installation that promotes good operation and maintenance.
3)Select the control systems that allow the boiler to operate safely and efficiently.
4)Select the control systems that will support the boiler in supplying dry steam to the plant at the required pressure(s) and flowrate(s).
5)Identify the fuel to be used and, if necessary, where and how the fuel reserve is to be safely stored.
If the impurities in the boiler feedwater are not dealt with properly, carryover of boiler water into the steam system can occur. This may lead to problems elsewhere in the steam system, such as:
The quality of the water used to produce the steam in the boiler will have a profound effect on meeting the objectives such as safe operation, maximum combustion and heat transfer efficiency, minimum maintenance and long working life.
1) Set up the air preheater. One of the most effective measures to improve the thermal efficiency of thermal oil heater is to use an air preheater for heat recovery. 2) Use waste heat boiler for heat recovery. The waste heat boiler uses the waste heat in the flue gas exhausted from the thermal oil heater to heat water or generate steam.
Normally a boiler is provided with two independent sensors for emergency low water level burner cut-outs. So this would never happen. However, if it does, don't take any chances! Shut off the burners immediately!
Before you start raising the level in the boiler you have to find out if any part of the furnace walls has been overheated. If you raise the level over a glowing steel-wall then the boiler might produce more steam than the safety valves can handle and a nasty explosion would be the result.
If the final temperature of feed water doesn’t reach the saturated temperature after being heated by an economizer, (that is, the feed water has not reached the boiling state), we call the economizer as a nonsteaming economizer. Generally, the final temperature is 30-50℃ lower than the saturated temperature.
Evaporation phase occurs in water wall tubes. Evaporation is the process to convert water into steam. Therefore water wall tubes should be designed and constructed to provide high heat absorption, minimum excess air level and highest boiler efficiency. Construction of water wall tubes should be also constructed to prevent air leakage into steam boiler, eliminate amount of heat losses and permit high heat release and combustion rate in the furnace.
Construction of water wall tubes must provide high quality of the supporting component such as tubes, casing, refractory, lagging, tile, fin, and so on. Best construction will reduce heat loss and maintenance. Construction of water wall tubes can be classified into four types such as:
