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.
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.
The dry bottom hopper is formed by bending the lower part of the water wall of the front and rear walls inward. The main function is to gather, cool and automatically discharge ash. It is also convenient for the connection and sealing of the lower header and the ash well.
Coal-fired boilers refer to boilers that use various kinds of coals as fuel and convert the heat value of coals to steam or hot water.
Some specific parameters should be provided to calculate the theoretical coal consumption of a set of 20 tph coal-fired boiler. If the rated steam pressure is 1 MPa, the heat value of coal is 7000 kcal / kg, the boiler inlet water temperature is 20 ° C, and the boiler thermal efficiency is 80%, the daily coal consumption is 50-56 tons.
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.
Compared with the price of a traditional coal-fired boiler, the operation cost of a gas-fired boiler is relatively high. So, users need to consider the price and quality before purchasing a boiler. For a gas-fired boiler, the energy-saving performance is more important than the boiler price. One year is enough for a gas-fired boiler with good energy-saving performance to save the extra costs of the boiler proper. And, the gas consumption is an important indicator to measure the energy-saving performance of a boiler.
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 combustion air preheater is definitely one of heat exchanger applications. Based on Figure 1 below, flue gas simply leaves steam boiler and passes via air preheater. The combustion air is passed through this equipment too to increase its temperature before being combined with boiler fuel.
Because the temperature of combustion air is lower than the temperature of flue gas, combustion air receive heat transfer from flue gas through combustion air preheater in the process of convection heat transfer. The heat transfer make temperature of flue gas lower and consequently minimizes its heat loss and also decreases the air temperature to stack.
