A reforming device for burning biomass in a circulating fluidized bed coal-fired boiler

Abstract

The invention discloses a recirculating fluidized bed coal-fired boiler biomass combustion retrofitting device. The retrofitting device comprises a hearth, and the lower end and the side end of the hearth are provided with a cooler and a material returning system optimizing device correspondingly; the lower end of the material returning system optimizing device is provided with an air blower, andthe side end of the material returning system optimizing device communicates with a filter, a coal economizer and an air preheater; the air preheater communicates with an ash remover, and the ash remover communicates with a chimney through an induced draft fan; the side end of the hearth is provided with a feeding system; and the feeding system comprises a feed inlet, an air locking device is arranged in the feed inlet, and the feeding system communicates with a conveying system. According to the recirculating fluidized bed coal-fired boiler biomass combustion retrofitting device, by retrofitting the conveying system and the feeding system, biomass conveying and passing are facilitated, the boiler load is increased, meanwhile, biomass combustion fly ash is further collected, an ash hopperconnected with the ash remover in a boiler is additionally provided with a fly ash recirculation pipe, and the ash returning amount of the hearth in a boiler system is effectively increased; and by arranging the low-pressure coal economizer, the smoke exhaust temperature is lowered, and the smoke exhaust efficiency is improved.

Description

Technical field [0001] The invention belongs to the field of boiler reforming devices, in particular to a reforming device for burning biomass in a circulating fluidized bed coal-fired boiler. Background technique [0002] Coal-fired boilers have been reformed and increased the proportion of biomass blending. In the process of burning biomass, due to the many differences in the properties of biomass and coal, many operational problems have occurred. [0003] The most intuitive problem of coal-fired boilers is that the capacity of the conveying system and the feeding system is insufficient, or the existing conveying system and the modification system cannot carry the design load of the boiler's steam production, which affects the stability. [0004] In the control of circulating fluidized bed bed temperature, the control of the amount of returned ash is the most effective measure. However, the ash content of biomass is lower than that of coal, and the amount of returned ash often cann...

AI Technical Summary

Problems solved by technology

[0003] The most intuitive problem with coal-fired boilers is that the capacity of the conveying system and the feeding system is insufficient, or the existing conveying system and the reforming system cannot carry the design load of the steam produced by the boiler, which affects the stability

[0004] In the control of circulating fluidized bed bed temperature, the control of the amount of returned ash is the most effective measure, but the ash content of biomass is lower than that of coal, and the amount of returned ash often cannot meet the needs of operation

Especially at the initial stage of furnace start-up, if the feeding device has been inspected and cleaned during the shutdown, it will take a very long process to establish a normal ash level of the returned material. Compared with coal-fired, biomass not only contains less ash, but also is fine and Light, the cyclone separator is difficult to capture, even the normal biomass boiler also faces the problem of insufficient return material

[0005] At this time, the temperature in the furnace is high due to the lack of returned ash, and the oxygen content is relatively high due to the minimum fluidization air volume requirement, and the NO X control is a very difficult thing

Even with SNCR equipment, the denitrification efficiency is extremely low or even ineffective for high-temperature oxygen-enriched environments! Unlike coal-fired boilers, biomass boilers must also strictly control the temperature in the dilute phase zone

Because the melting point of biomass ash is much lower than that of coal-fired ash due to its rich potassium ions, the high temperature in the dilute phase zone will cause a large amount of molten ash to accumulate on the evaporation tube bundle or superheater screen in the furnace, blocking the flue gas passage, causing The speed of the flue gas flow increases, which intensifies the wear and causes the pipe to burst, and the accumulated excessive ash blocks sometimes fall into the bed to affect the fluidization and cause coking

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