The temperature of flue gas generated by a biomass-fired boiler is relatively high. But it is not corrosive. So, it is suitable to use heat resisting glass fiber needled felt bag which has a good use effect. Moreover, this kind of cloth bag is not very expensive.
1. The fuel volume is 1 / 30 ~ 40 of the raw material volume after molding;
2. The specific gravity is 10-15 times of the raw material, and the moisture content is between 12% and 18% (the moisture content of coal is below 10-15);
3. The net calorific value can reach 3500-4500 kcal (the net calorific value of class II bituminous coal is 3700-4700 kcal / kg);
4. The ash content is less than 10% (the ash content of coal is more than 20%);
5. Volatile matter ≥ 65.62% (volatile matter of class II bituminous coal≥20%).
6. Biomass fuel belongs to renewable clean energy, which is the same as wind energy and solar energy. The biomass fuel is rich in resources, it can ensure the sustainable use of energy.
7. The sulfur content and nitrogen content of biomass fuel are low, the amount of SOx and NOx generated in the combustion process is low.
The selection of dust collector for coal-fired boilers is determined by the purpose and requirements of dust collecting. If the requirement is just dust collecting, the impulse bag filter is a good choice, the efficiency can reach up to 99%. If both dust collecting and desulfurization are required, you should choose bag filter plus spray desulfurization. Bag filter plus double alkali desulfurization is suggested for higher requirements.
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.
Fuel-to-steam efficiency is a measure of the overall efficiency of the boiler. It accounts for the effectiveness of the heat exchanger as well as the radiation and convection losses. It is an indication of the true boiler efficiency and should be the efficiency used in economic evaluations. As prescribed by the ASME Power Test Code, PTC 4.1, the fuel-to-steam efficiency of a boiler can be determined by two methods: the InputOutput Method and the Heat Loss Method.
A steam boiler plant must operate safely, with maximum combustion and heat transfer efficiency. To help achieve this and a long, low-maintenance life, the boiler water can be chemically treated.
The operating objectives for steam boiler plant include:
Safe operation.
Maximum combustion and heat transfer efficiency.
Minimum maintenance.
Long working life.
The quality of the water used to produce the steam in the boiler will have a profound effect on meeting these objectives.
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:
The term “boiler efficiency” is often substituted for thermal efficiency or fuel-to-steam efficiency. When the term “boiler efficiency” is used, it is important to know which type of efficiency is being represented. Why? Because thermal efficiency, which does not account for radiation and convection losses, is not an indication of the true boiler efficiency. Fuelto-steam efficiency, which does account for radiation and convection losses, is a true indication of overall boiler efficiency. The term “boiler efficiency” should be defined by the boiler manufacturer before it is used in any economic evaluation.
