Circulating fluidized bed boiler for burning low-heat-value high-ash fuel

Abstract

A circulating fluidized bed boiler for burning low-heat-value high-ash fuel contains a hearth, a primary air chamber, a cyclone separator, a cyclone separator, a charge leg, a return valve, a slag discharge pipe, a tail flue and a gas-solid heat exchange bed. The gas-solid heat exchange bed is arranged below the primary air chamber and connected with the hearth through a connection pipe and a gas-solid separation device. The hearth is connected with the gas-solid heat exchange bed through the slag discharge pipe. The gas-solid heat exchange bed comprises a heat exchange bed air chamber, a heatexchange bed air cap, a heat exchange bed heat exchange chamber and a heat exchange bed slag discharge pipe. The heat exchange bed air chamber is connected with an air preheater through a gas pipeline. A large quantity of high-temperature ash residues in the hearth are discharged into the gas-solid heat exchange bed through the slag discharge pipe, and primary air is heated by the air preheater,is led into the gas-solid heat exchange bed and then enters the primary air chamber. By means of the circulating fluidized bed boiler, the temperature of the primary air can be greatly improved, and the requirement for stable burning of the low-heat-value high-ash fuel is met; and on the other hand, the heat of the large quantity of ash residues of the high-ash fuel can be recycled, the slag discharge heat loss is reduced, and thus the overall heating efficiency of the boiler is improved.

Description

technical field [0001] The invention belongs to the field of combustion application of circulating fluidized bed boilers, and discloses a circulating fluidized bed boiler for burning fuels with low calorific value and high ash content. Background technique [0002] Circulating fluidized bed boilers have the advantages of wide fuel adaptability and low pollutant emission levels, and are widely used in the combustion and utilization of inferior coal. my country has huge reserves of fuels with low calorific value and high ash content, such as oil shale semi-coke and gangue. At present, most of these fuels are processed by stacking and storage, and only a small amount of high-quality fuel is used for combustion in circulating fluidized bed boilers. The main influencing factor is that this type of fuel itself has a low calorific value, and it is difficult to burn stably under the general boiler design conditions. In addition, this type of fuel has a high ash content and a large ...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a circulating fluidized bed boiler for burning fuel with low calorific value and high ash, which is difficult to stably burn and a large amount of hot ash with high ash is lost to reduce the thermal efficiency of the boiler. The fluidized bed boiler can not only meet the requirements of stable combustion of fuel with low calorific value and high ash content, but also can effectively recover the heat of hot ash, reduce the heat loss of slag discharge, and improve the thermal efficiency of the boiler

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