A membrane-type water-cooled wall four-flue biomass circulating fluidized bed boiler

Abstract

A membrane water-cooled wall four-flue biomass circulating fluidized bed boiler, including a drum, a furnace, a cyclone separator, a return device, a second flue, a third flue, a fourth flue, an economizer, and a dust collector appliance, induced draft fan, chimney. The furnace, the second flue and the third flue are surrounded by membrane water-cooled walls; in the lower part of the furnace and the inner surface of the flue gas outlet, the cyclone separator and the inner surface of the flue gas outlet, the second flue and the third flue Refractory castables are laid around the connecting parts of the flue; a medium-temperature screen superheater is arranged at the upper end of the second flue; high-temperature and low-temperature convection superheaters are spaced in the third flue; the middle wall adopts a tapered wall structure; low-temperature convection superheater The first water spray desuperheater and the second water spray desuperheater are respectively arranged between the high temperature convection superheater and the medium temperature screen convection superheater. The invention improves the combustion heat energy utilization rate of the biomass fluidized bed boiler, reduces the wear and alkali metal corrosion of the inner wall of the flue by high-speed and high-temperature flue gas, and enhances the wear resistance of the wall surface.

Description

technical field [0001] The present invention relates to a biomass circulating fluidized bed boiler, especially a membrane type water-cooled wall four-flue high-efficiency biomass circulating fluidized bed boiler that makes full use of combustion heat energy. Background technique [0002] As society's demand for energy increases day by day, fossil fuels, which are the main source of energy, are rapidly decreasing. Therefore, looking for a renewable alternative energy source has become the focus of widespread concern in society. Biomass is the only energy that can be regenerated, directly stored and transported, and can achieve less harmful gas emissions. Therefore, boilers that use biomass to generate electricity have become the latest development trend of boilers. As biomass fuels such as Vitex twigs and corn stalks, when the circulating fluidized bed combustion method is used, there are mainly problems in the following aspects: (1) The calorific value of biomass fuels is r...

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Problems solved by technology

As biomass fuels such as Vitex twigs and corn stalks, when the circulating fluidized bed combustion method is used, there are mainly problems in the following aspects: (1) The calorific value of biomass fuels is relatively low. In order to make the outlet steam reach the predetermined temperature, it takes more The heating area; (2) The content of silicon in the ash after biomass fuel combustion is relatively high, and the ash particles are relatively hard. At a high smoke velocity, the inner wall of the flue is severely worn; (3) The biomass fuel contains alkali There are many metals. When the temperature of the inner wall of the flue is high, the alkali metal contained in the flue gas is more corrosive to the wall.

At present, research on biomass circulating fluidized bed boilers has been carried out: the patent number is ZL200610088935.5, which discloses "biomass circulating fluidized bed combustion method and biomass circulating fluidized bed". A low-temperature superheater is installed in the flue, which solves the problems of uneven temperature distribution and slagging in the furnace of the biomass circulating fluidized bed boiler; the patent number is ZL 200720309013.2, which discloses a "biomass circulating fluidized bed boiler". , eccentric cyclone separator, feeder, superheater, economizer and air preheater, etc., which solve the problems of agglomeration, slagging and ash deposition in biomass circulating fluidized bed boilers. The above two boilers The structure is simple, but the heat utilization rate of combustion is low, which is not conducive to low-carbon energy saving; the patent No. ZL 200820108769.5 discloses a "circulating fluidized bed boiler for burning straw-like biomass", which includes a belt feeder, Compression molding equipment, furnace, heating surface of water-cooled evaporation panel, cyclone separator, feeder, panel low-temperature superheater, convection high-temperature superheater and economizer, air preheater, etc. The boiler has smooth feeding, fluidization Uniformity, the bed is not easy to agglomerate, coke, high combustion efficiency, etc., but the conversion rate of combustion heat energy is low, the wear of the inner wall of the flue and the corrosion of alkali metal are relatively large

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