The proximate analysis of coal is to dry, heat and burn coal samples as required to get the percentage of moisture, volatiles, fixed carbon and ash in the coal and learn about the characteristics of coal combustion.
Volatile matter in coal refers to the components of coal, except for moisture, which are liberated at high temperature in the absence of air. This is usually a mixture of short- and long-chain hydrocarbons, aromatic hydrocarbons and some sulfur. Volatile matter also evaluate the adsorption application of an activated carbon. The volatile matter of coal is determined under rigidly controlled standards. In Australian and British laboratories this involves heating the coal sample to 900 ± 5 °C (1650 ±10 °F) for 7 min. Also as the rank of coal increases the volatile matter decreases (AMK).
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 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.
Question details (Performance):The steam pipe vibrates violently and has a dull impact sound.Answer: fault reason: There is air in pipeline ; automatic air vent valve is not turned on; or it is out of order. Troubleshooting: Check all the air release valves on the water supply pipe and the air release valves on the top of the boiler tube for gas storage. If the valve fails, it should be replaced immediately.
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,
(Question details) Specific performance:The wall thickness of several boiler tubes was significantly reduced in a large area, the remaining wall thickness was 2.0mm, and some furnace tubes were corroded and worn out. Furnace tube wall is covered with a thick layer of uneven scale, the surface of the scale is brick red and black, scale layer is loose, and it is easy to remove the inner wall of the furnace tube, after removing, the furnace tube wall covered with a layer of corrosion pits. There is a thin layer of brick red corrosion on the outer wall of boiler tube, some of which are attached with black adhesive. Answer: Fault reason:1. The boiler is seriously short of water.2. Poor water circulation and uneven combustion.3. The unqualified quality of the boiler water and undemanding chemical supervision make the inner wall of the pipe corrode and scale, causing the pipe overheat and reduction of the strength.4. Due to the presence of impurities and scale, the furnace tube is blocked ins
