The economizer is a heat exchanger equipment which utilizes heat recovery of flue gases to heat feedwater. It can increase boiler efficiency, reduce the temperature of flue gas and save the fuel by absorbing recovery of flue gases. Besides, the feedwater is heated through the economizer before it is supplied into steam drum to decrease the thermal stress of the steam drum wall caused by temperature difference, which can improve the operating conditions of steam drum and prolong the service life of the steam drum.
A process load is usually a high-pressure steam load. A process load pertains to manufacturing operations, where heat from steam or hot water is used in the process. A process load is further defined as either continuous or batch. In a continuous load, the demand is fairly constant - such as in a heating load. The batch load is characterized by short-term demands. The batch load is a key issue when selecting equipment, because a batch-type process load can have a very large instantaneous demand that can be several times larger than the rating of the boiler. For example, based on its size, a heating coil can consume a large amount of steam simply to fill and pressurize the coil. When designing a boiler room for a process load with instantaneous demand, a more careful boiler selection process should take place.
System load is measured in either BTUs or tons of steam (at a specific pressure and temperature). It would be nearly impossible to size and select a boiler(s) without knowing the system load requirements. Knowing the requirements leads to the following information:
The boiler(s) capacity, taken from the maximum system load requirement.
The boiler(s) turndown, taken from the minimum system load requirement.
Conditions for maximum efficiency, taken from the average system load requirement.
Determining the total system load requires an understanding of the type(s) of load in the system. There are three types of loads: heating, process, and combination.
Steam boilers with a low NOx system are specially designed to minimize the environmental impact with the production of dry saturated steam. This type of boiler incorporates a stainless steel economizer with a cross flow integrated within the boiler and that, consequently, allows to reach maximum efficiency.In addition, it has a natural gas burner with low NOx emissions.
Question details (Performance):Dust collecting cloth bag damages a lot. Answer: The cause of the problem: As the biomass-fired boiler fuel moisture is high, and bag material is general PPS, which will reduce the base fabric of the bag in the case of high temperature, high humidity, hydrolysis, oxidation, and cause damage; In addition, the fuel moisture is high and it cannot be completely burned in the furnace, so it burns in the dust collector, which is also an important reason for the damage of the cloth bag.Troubleshooting:(1) Design by full consideration of high fuel moisture, choosing the appropriate induced draft fan, if the existing design is not enough then consider change the induced draft fan.(2) If induced air volume is sufficient, a proper distribution of the first and second wind should be considered. Generally, the fuel with high moisture and light quality such as wood chips, straw and wheat straw hood, the secondary air volume should be increased. For bark, miscellaneous
(Question Details) Specific Performance:(1) There are blasting sounds in the furnace, and the furnace chamber is under positive pressure. There is smoke emitted from the combustion chamber in a leakage. In severe cases, the explosion-proof door of the boiler body opens.(2) Drum water level drops rapidly and the feedwater flow rate is not abnormally larger than steam flow. MFT acts when the water level is below -280mm.(3) Drum pressure, steam flow rate, exhaust temperature decrease, smoke temperature difference increases on both sides.(4) The negative pressure at the inlet of the flue and suction fan becomes smaller and the temperature difference between the two sides increased. (5) Smoke temperature decreases at the inlet and outlet of the cyclone separator, and the temperature of the material returned is low.(6) Bed pressure increases, bed materials clean, fluidization poof, bed temperature distributes unevenly and bottom slag discharge difficultly. Answer：cause of failure:(1) Fly ash
Question details (Performance):1. The furnace wall at the coal economizer leaks water and steam with abnormal sound.2. The water level in the boiler drops sharply, and the water supply is obviously greater than the evaporation capacity.3. Smoke exhaust temperature and water outlet temperature rise.Answer: Fault reason:1. The water quality does not reach standard, and the oxygen in the water is decomposed into corroded pipe walls when the temperature rises.2. The low feed water temperature and smoke exhaust temperature make the inner and outer wall of the coal economizer pipe produce acid corrosion, or flying ash wear the pipe wall thin. 3. The pipe is blocked by impurities, causing overheating.4. Poor materials, defects in manufacturing, installation and maintenance. Troubleshooting:1. When economizer is slightly broke, it still maintains boiler operation, and the gap seems will not expand rapidly, in this case, load operation should be reduced, and start the spare boiler immediately,
