CN212549031U

CN212549031U - Desulfurization and denitrification dust removal system based on heat supply of waste heat of flue gas of biomass boiler

Info

Publication number: CN212549031U
Application number: CN202020586805.XU
Authority: CN
Inventors: 肖峰; 张宝来; 郑乐宇; 于畅; 万里宁; 裴育峰
Original assignee: Northeast Electric Power Design Institute of China Power Engineering Consulting Group
Current assignee: Northeast Electric Power Design Institute of China Power Engineering Consulting Group
Priority date: 2020-04-17
Filing date: 2020-04-17
Publication date: 2021-02-19
Anticipated expiration: 2030-04-17

Abstract

A desulfurization, denitrification and dust removal system based on heat supply of waste heat of flue gas of a biomass boiler integrates an integrated process of a boiler flue gas heating system, an air heating system, a desulfurization and dust removal system, a low-temperature SCR (selective catalytic reduction) denitration system and a heat regeneration system, so that the biomass boiler reaches an ultralow emission standard. The utility model is characterized in that economizer export flue gas connects gradually SCR flue gas heater, air heater, desulfurization dust collector, draught fan, and draught fan exit linkage backheat flue gas heater (GGH) low temperature end entry, and GGH low temperature end export connects gradually SCR flue gas heater, low temperature SCR denitrification facility, and low temperature SCR denitrification facility exit linkage GGH high temperature end entry, and pressure boost flue gas fan and chimney are connected to GGH high temperature end export. The utility model has the advantages of utilizing the waste heat of the boiler flue gas, ensuring the boiler efficiency and realizing the ultra-low NOX emission; the heat exchanger, the air preheater and the desulfurization, denitrification and dust removal system are integrated; various furnace types of biomass can be applied; the ultralow emission under all operating conditions is ensured; the existing mature technology integrates innovation.

Description

Desulfurization and denitrification dust removal system based on heat supply of waste heat of flue gas of biomass boiler

Technical Field

The utility model belongs to biomass boiler electricity generation field especially relates to biomass boiler flue gas pollutant processing system's improvement, realizes biomass boiler flue gas ultralow process systems who discharges.

Background

The national standard for biomass boiler NOx emission stipulates that the emission is 100 mg/standard cubic meter, and the low-temperature staged combustion low-NOx technology, the in-furnace selective non-catalytic reduction (SNCR) technology and the like are adopted at present to meet the standard requirements. Due to the vigorous development of green energy, the pollutant emission of the biomass boiler is increasingly increased, and the emission of the biomass boiler is regulated by environmental protection departments of provinces, cities and autonomous regions in China to execute the ultralow emission standard of the coal-fired boiler according to the emission reference, namely that the NOX emission is 50 mg/standard cubic meter. Due to the basic characteristics of low-temperature combustion, the biomass boiler is reliable when the primary NOx index reaches 100 mg/standard cubic meter by adopting low-NOx combustion technologies such as layered classification and flue gas recirculation, but the full-working-condition denitration efficiency reaches 50% under the condition that the SNCR in the boiler is required to be at the low-temperature combustion smoke temperature of 600-750 ℃ and is separated from a normal reduction reaction temperature window (above 850 ℃), and the ultra-low emission is not possible. At present, several environmental protection units in China develop technologies based on SNCR additives, try to influence and change the temperature window of chemical reaction, and at the test stage, whether reducing inorganic matters are sprayed into a hearth to react with high-temperature metal or not has no practical evidence at present. And in addition, some projects apply an oxidation denitration technology, which is essentially characterized in that under the condition that nitrogen oxides increased by boiler combustion are strictly removed, the total amount of the nitrogen oxides is increased by continuous oxidation, dangerous chemicals such as nitrates and the like are generated, an aftertreatment system is complex, the investment of the project is greatly increased, and the technical and economic risks are increased.

By combining the analysis, the denitration ultra-clean emission of the biomass boiler is limited to a widely applied Selective Catalytic Reduction (SCR) technology at present. The SCR reactor of the conventional coal-fired unit is arranged in front of the air preheater, and the high reaction efficiency is realized by utilizing the high reaction temperature of the SCR reactor, so that the SCR reactor is widely applied to the coal-fired unit. For a biomass boiler, the content of alkali metal in the fly ash is very high, the activity of the catalyst is seriously influenced, meanwhile, the fly ash seriously blocks the pores of the catalyst, and the application of a front-mounted SCR system is not suitable, the SCR system is necessarily arranged at the rear part of a desulfurization and dust removal device, and the reliability of the catalyst is ensured under the condition of clean flue gas. At present, the domestic low-temperature SCR technology is rapidly advanced, the dust content and the sulfur content of the clean flue gas after denitration and dust removal are very low, most heavy metals are also removed, the operation condition of the catalyst is very good, and the denitration efficiency can be ensured at a lower temperature (200-230 ℃). However, the post-positioned low-temperature SCR denitration system has a serious defect that the temperature of flue gas is very low after desulfurization and dust removal, and is generally not more than 85 ℃. Although a regenerative technology can be adopted, the temperature rise of the flue gas at the inlet of the NOX reactor also needs to reach more than 30 ℃, and if the flue gas is supplied by a power generation steam-water system, the heat economy of a unit is greatly reduced. The main mode of the traditional domestic biomass boiler postposition low-temperature SCR denitration meeting the temperature window is natural gas combustion heat compensation, the natural gas acquisition mode is difficult, the operation cost is higher, the economy of a biomass unit is seriously influenced, and only a few biomass units in the developed area of the southeast coastal economy have high electricity price and large industrial gas consumption and adopt the afterburning mode.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at discharging the rearmounted low temperature SCR deNOx systems energy supply problem of inevitable selection to solving biomass boiler ultra-clean, on the basis of guaranteeing boiler efficiency, realize the utilization of ultralow NOX emission and boiler flue gas waste heat.

In order to realize the above-mentioned utility model purpose, the utility model provides a SOx/NOx control dust pelletizing system based on heat supply of biomass boiler flue gas waste heat, its characterized in that: including SCR flue gas heater, air heater, desulfurization dust collector, backheat flue gas heater, low temperature SCR denitrification facility, the draught fan, pressure boost flue gas fan, economizer export flue gas connects gradually SCR flue gas heater, air heater, desulfurization dust collector, the draught fan, draught fan exit linkage backheat flue gas heater low temperature end entry, backheat flue gas heater low temperature end export connects gradually SCR flue gas heater, low temperature SCR denitrification facility exit linkage backheat flue gas heater high temperature end entry, backheat flue gas heater high temperature end exit linkage pressure boost flue gas fan and chimney.

The inlet flue gas temperature of the low-temperature SCR denitration device is more than 200 ℃.

1. The utility model discloses a guarantee under the unchangeable condition of efficiency at biomass boiler, realize the utilization of afterbody flue gas waste heat to satisfy the temperature requirement of low temperature SCR system denitration, guarantee higher denitration efficiency.

2. Integration boiler air heating system and SOx/NOx control dust pelletizing system reduce with the cross fit of boiler body system, and is the same with the effect of original boiler performance guarantee scope.

3. The applicable biomass boiler has various types and can realize the ultralow emission of NOX.

4. The ultra-low NOx emission index of the biomass boiler under all operating conditions is met.

Drawings

Fig. 1 is a flow chart of the present invention.

Detailed Description

Referring to fig. 1, the utility model discloses embodiment includes SCR flue gas heater, air heater, desulfurization dust collector, backheat flue gas heater, low temperature SCR denitrification facility, the draught fan, pressure boost flue gas fan, economizer export flue gas connects gradually SCR flue gas heater, air heater, desulfurization dust collector, the draught fan, draught fan exit linkage backheat flue gas heater low temperature end entry, backheat flue gas heater low temperature end export connects gradually SCR flue gas heater, low temperature SCR denitrification facility exit linkage backheat flue gas heater high temperature end entry, pressure boost flue gas fan and chimney are connected to backheat flue gas heater high temperature end exit.

Because the low-temperature SCR denitration device is arranged behind the desulfurization and dust removal system with ultralow emission, the catalyst has good running environment, the activity of the catalyst is ensured, the denitration efficiency is higher at about 230 ℃, and the ultralow emission of NOX can be met. The regenerative flue gas heater (GGH) can heat the flue gas at the outlet of the desulfurization and dust removal device to about 200 ℃ from 80-85 ℃ by utilizing the favorable condition of higher temperature of the flue gas at the outlet of the low-temperature SCR denitration device, and the temperature rise of the inlet flue gas of the low-temperature SCR denitration device, which needs heat compensation, is only 30 ℃. The temperature of flue gas at the outlet of a biomass boiler economizer is generally 260-280 ℃, an SCR flue gas heater is additionally arranged, sufficient heat exchange end difference is achieved, the temperature of the flue gas at the outlet of a GGH can be heated to 230 ℃ from 200 ℃, and the denitration efficiency of the low-temperature SCR denitration device is guaranteed. The temperature of the flue gas at the inlet of the low-temperature SCR denitration is increased by 30 ℃, and the temperature of the flue gas at the outlet of the economizer is reduced by about 30 ℃ in the SCR flue gas heater due to the equivalent total amount of the flue gas, namely the temperature is reduced from 260-280 ℃ to 230-250 ℃. The outlet air temperature of the biomass boiler air preheater is 180-200 ℃, the outlet smoke temperature of the NOX smoke heater meets the heat exchange condition in the air preheater, and the outlet air temperature requirement of the air preheater can be guaranteed. In a similar way, the exhaust gas temperature of the biomass boiler is reduced by about 110-120 ℃ from the generally higher temperature of 140-150 ℃, lower temperature emission is realized, and the exhaust gas loss of the boiler is reduced. Like this, set up NOX flue gas heater through the economizer export and guarantee low temperature SCR denitrification facility entry temperature, maintain higher denitration efficiency, realize NOX minimum emission, air heater maintains original boiler hot-blast temperature unchangeable simultaneously, and boiler exhaust gas temperature reduces about 30 ℃, makes boiler efficiency guarantee, has realized the utilization of ultralow NOX emission and boiler flue gas waste heat.

The conventional biomass boiler body comprises an air preheater, the smoke emission boundary of boiler performance guarantee is air preheater outlet smoke, and the air inlet boundary is a fan inlet. This application is for guaranteeing engineering project in time to use, reduces the cross fit with boiler body system, and the fume emission border of stipulating the boiler supply range is low temperature economizer exhanst gas outlet, and the air admission border is furnace air inlet, and this is convenient to realize in engineering project, and the energy meter that low temperature economizer export flue gas carried is listed as the loss, and the energy meter that furnace inlet air carried is listed as the income, and the effect with original boiler performance guarantee range is the same. Including the SCR flue gas heater who guarantees low temperature SCR denitrification facility entry gas temperature and the air heater who guarantees furnace entry air temperature in this application system, still include conventional desulfurization dust pelletizing system and low temperature SCR denitrification facility and backheating system simultaneously.

The biomass boiler furnace type that this application is suitable for is various, all can realize NOX minimum emission. Because the primary NOX of low-temperature combustion of the circulating fluidized bed boiler is low, the low-temperature SCR denitration device adopts low operation temperature, and the denitration efficiency reaches 50 percent, so that the environment-friendly ultralow emission requirement can be met. To the wide reliable grate boiler of operation of fuel adaptability, because native NOX is higher reaches 400 milligrams/standard cubic meter, adopts the utility model discloses, guarantee that low temperature SCR denitrification facility entry smoke temperature more than 230 ℃, denitration efficiency reaches 90%, can reach NOX ultralow emission equally.

This application can utilize the economizer flue bypass of boiler body, improves economizer export flue gas temperature when the boiler low-load operation, guarantees low temperature SCR denitrification facility's denitration efficiency, reaches the ultralow emission of full operating mode NOX.

Various devices in the system are conventional products and are widely applied. The ultralow emission of biomass boiler NOX is realized to this application, is boiler heat transfer system and SOx/NOx control dust pelletizing system's integrated innovation.

Claims

1. The utility model provides a SOx/NOx control dust pelletizing system based on heat supply of biomass boiler flue gas waste heat which characterized in that: including SCR flue gas heater, air heater, desulfurization dust collector, backheat flue gas heater, low temperature SCR denitrification facility, the draught fan, pressure boost flue gas fan, economizer export flue gas connects gradually SCR flue gas heater, air heater, desulfurization dust collector, the draught fan, draught fan exit linkage backheat flue gas heater low temperature end entry, backheat flue gas heater low temperature end export connects gradually SCR flue gas heater, low temperature SCR denitrification facility exit linkage backheat flue gas heater high temperature end entry, backheat flue gas heater high temperature end exit linkage pressure boost flue gas fan and chimney.

2. The desulfurization, denitrification and dust removal system based on heat supply by waste heat of flue gas of biomass boiler according to claim 1, characterized in that: the inlet flue gas temperature of the low-temperature SCR denitration device is more than 200 ℃.