The fineness of pulverized coal is an important indicator to measure the pulverized coal quality.
In terms of combustion, the particle size of pulverized coal is expected to be as small as possible to facilitate the ignition and combustion, reduce the heat loss of incomplete combustion, the amount of air supply and heat loss of exhaust smoke.
In terms of pulverized coal milling, the particle size of pulverized coal is expected to be as coarse as possible to reduce the power consumption and steel consumption. Therefore, when selecting the fineness of pulverized coal, a compromise of the two aspects is taken as the economic fineness.
It shall be determined through combustion adjustment tests according to the fuel properties and the type of pulverizing equipment.
The function of high and low level alarms. Low-level alarms will draw attention to low boiler water level and, if required, shut down the boiler. High-level alarms protect plant and processes.
Where boilers are operated without constant supervision (which includes the majority of industrial boilers) low water level alarms are required to shut down the boiler in the event of a lack of water in the boiler. Low level may be caused by:
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.
Stack temperature is the temperature of the combustion gases (dry and water vapor) leaving the boiler. A well-designed boiler removes as much heat as possible from the combustion gases. Thus, lower stack temperature represents more effective heat transfer and lower heat loss up the stack. The stack temperature reflects the energy that did not transfer from the fuel to steam or hot water. Stack temperature is a visible indicator of boiler efficiency. Any time efficiency is guaranteed, predicted stack temperatures should be verified.
Stack loss is a measure of the amount of heat carried away by dry flue gases (unused heat) and the moisture loss (product of combustion), based on the fuel analysis of the specific fuel being used, moisture in the combustion air, etc.
Condensing boilers can achieve up to 98% thermal efficiency, compared to 70%-80% with conventional designs (based on the higher heating value of fuels). Typical models offer efficiencies over 90% when the return water temperature is at 110 ºF or less; the lower the return water temperature, the higher the efficiency gain.
Safety is always a top priority when working with industrial boilers, at least it should be. Fortunately, safety has become less of an issue with more modern water tube boilers. Compared to traditional fire tube boilers, water tube boilers are far safer, almost to the point where you don’t have to worry about a catastrophic explosion taking place.
(Question Details) Specific Performance:The pipe of superheater bursts in circulating fluidized bed boiler operation.The bed pressure indicator fluctuates little. Answer: causes of failure:(1) Design Factors.(2) Manufacturing process, installation and maintenance quality.(3) The temperature control device is unreasonable or does not work properly.(4) Effect of operating conditions on overheating and explosion of superheater. Troubleshooting:(1) Report the fact to operator on duty and require operating the boiler in low load.(2) When the overheat damage is serious,please report it to operator on duty and require stoping the boiler immediately to prevent blowout of the near pipes.(3) Adjust the steam temperature as much as possible within the normal range.(4) If the superheater tube is not damaged badly, it has little effect on the temperature level of the steam, and it can be allowed to run in a low load range for a short period of time.
(Question Details) Specific Performance:(1) The bed temperature has risen sharply.(2) The oxygen level drops even to zero.(3) The current of the primary blower is reduced, and the wind pressure in the wind chamber is high and fluctuates.(4) The furnace negative pressure increases and the induced draft fan current decreases.(5) Difficulties in slagging.(6) If coking in low temperature, the bed temperature, bed pressure distribution is uneven, the deviation is too large, the bed pressure, the plenum pressure, the bed temperature is not normal, and the local bed temperature measurement point is not normally raised or lowered.(7) The bed pressure indicator value fluctuates little. Answer: causes of failure :(1) Improper operation, resulting in overheated bed temperature and coking.(2) The primary air volume during operation is kept too small, which is lower than the minimum fluidized air volume, so that the material can’t be well fluidized but piled up, the temperature field of the entire
