A biomass boiler ultra-low emission system and method for synergistic desulfurization and enhanced self-denitrification.

Abstract

This invention discloses a synergistic deacidification-enhanced self-denitrification ultra-low emission system and method for biomass boilers, relating to the fields of renewable energy utilization and energy conservation and emission reduction. It includes a combustion module, a dust removal, deacidification, and denitrification module, and a tail gas emission module. The dust removal, deacidification, and denitrification module is located in the flue between the combustion module and the tail gas emission module, and includes an alkaline injection system, a dust removal system, and an SCR self-denitrification system. After the biomass combustion flue gas from the combustion module is discharged into the flue, atomized alkaline solution is sprayed into the flue through the alkaline injection system, and high-temperature dust removal is achieved through the dust removal system. The SCR self-denitrification system is used to enhance the self-denitrification of the dust-removed biomass combustion flue gas. The tail gas emission module discharges the flue gas after dust removal, deacidification, and denitrification into the atmosphere. This invention can achieve the synergistic removal of NOx and acidic gases from biomass combustion flue gas, achieving ultra-low emissions of NOx, SOx, and HCl from biomass boilers.

Description

Technical Field

[0001] This invention belongs to the field of renewable energy utilization and energy conservation and emission reduction, and specifically relates to an ultra-low emission system and method for biomass boilers with synergistic deacidification and enhanced self-denitrification. Background Technology

[0002] Biomass, as an environmentally friendly renewable energy source with "zero CO2 emissions," is abundant in my country, with great potential for energy utilization. Biomass power generation is currently one of the most common and effective methods of biomass energy. However, similar to traditional fossil fuels such as coal, oil, and natural gas, biomass combustion also produces large amounts of pollutants such as NOx and SOx, causing environmental pollution.

[0003] To meet current NOx emission standards, biomass power plants typically employ oxygen-deficient or micro-oxygen combustion in boiler furnaces. However, this method results in the presence of a large amount of NH3 in the flue gas in addition to NOx and SOx. Furthermore, as the flue gas temperature decreases, the large amount of NH3 present in the flue gas reacts with acidic gases such as SO2 / SO3 and HCl to form ammonium bisulfate (ABS) or ammonium chloride. This leads to damage such as deposition and corrosion in downstream equipment of the boiler, such as air preheaters, severely restricting the safe operation of biomass boilers.

[0004] Furthermore, biomass fuels contain a large amount of chlorine, which produces HCl acid gas during high-temperature combustion, a major cause of corrosion on boiler heating surfaces. Meanwhile, with the current trend of thermal power plants achieving ultra-low emissions, SO3 emissions, due to a lack of control measures and their significant harmfulness, have increasingly attracted attention, and SO3 emission control has become a new and widespread problem.

[0005] Therefore, there is an urgent need for a method that can effectively reduce the emissions of air pollutants such as NOx, SOx and HCl during the combustion of biomass boilers, so as to remove NOx and acidic gases (SOx and HCl) from the flue gas of biomass combustion. Summary of the Invention

[0006] To address the shortcomings and problems of traditional oxygen-deficient or micro-oxygen combustion methods in boiler furnaces, which cannot effectively reduce the emission of air pollutants such as NOx, SOx, and HCl during the combustion process of biomass boilers, this invention provides a biomass boiler ultra-low emission system and method with synergistic deacidification and enhanced self-denitrification.

[0007] The solution adopted by this invention to solve its technical problem is: a biomass boiler ultra-low emission system with synergistic deacidification and enhanced self-denitrification, including a combustion module, a dust removal, deacidification, and dedenitrification module, and a tail gas emission module. The dust removal, deacidification, and dedenitrification module is located in the flue between the combustion module and the tail gas emission module, and includes an alkaline injection system, a dust removal system, and an SCR self-denitrification system. After the biomass combustion flue gas from the combustion module is discharged into the flue, the alkaline injection system controls an atomizing injection device located in the flue to spray atomized alkaline solution into the flue, thereby removing acidic gases from the flue gas. The dust removal system is located between the alkaline injection system and the SCR self-denitrification system, and achieves high-temperature dust removal of the flue gas. The SCR self-denitrification system is used to enhance the self-denitrification of the dust-removed biomass combustion flue gas. The flue outlet is connected to the tail gas emission module, through which the biomass combustion flue gas after dust removal, deacidification, and dedenitrification is discharged into the atmosphere.

[0008] Furthermore, the combustion module includes a boiler furnace and a cyclone separator. The outlet of the furnace is connected to the inlet of the cyclone separator, and the flue gas after combustion in the furnace enters the cyclone separator. The bottom of the cyclone separator is also provided with a return channel, the end of which is connected to the inner cavity of the furnace.

[0009] Furthermore, a superheater is also provided in the flue between the cyclone separator and the dust removal, acid removal, and denitrification module to heat the high-temperature flue gas generated in the furnace, thereby improving thermal efficiency.

[0010] Furthermore, a flue gas composition analysis sensor is also installed in the downstream flue of the superheater.

[0011] Furthermore, the atomizing alkaline solution can be NaOH, KOH, Ca(OH)2 or other alkaline solutions with a concentration of 1% to 10; and the amount of alkaline solution sprayed into the flue, the molar ratio of alkaline substances to acidic gases in the flue gas is controlled within the range of 2:1 to 5:1.

[0012] Furthermore, the dust removal system is a high-temperature dust collector, which uses a metal filter membrane or a ceramic fiber filter membrane to achieve high-temperature flue gas dust removal.

[0013] Furthermore, the exhaust gas emission module includes a heat exchange system and a chimney. The heat exchange system includes an economizer, an air preheater, and an induced draft fan, which are sequentially arranged in the downstream flue of the SCR self-denitrification system along the flue gas flow direction, and the end of the flue is connected to the chimney.

[0014] This invention also provides a method for ultra-low emissions from a biomass boiler with synergistic desulfurization and enhanced self-denitrification, comprising the following steps:

[0015] S1. Biomass fuel is put into the furnace for combustion. The flue gas after combustion enters the cyclone separator. The unburned solid particles mixed in the flue gas discharged from the furnace are returned to the furnace for secondary combustion. The separated flue gas flows into the flue from the outlet of the cyclone separator.

[0016] S2. After receiving the concentration information of pollutants in the flue gas, the alkaline liquid injection system controls the atomizing injection device to atomize and spray alkaline liquid into the flue, thereby removing acidic gases from the biomass combustion flue gas in the flue.

[0017] S3. The flue gas after acid removal is dedusted by a dust removal system and then enters the SCR self-denitrification system to enhance the self-denitrification of biomass combustion flue gas.

[0018] S4. The biomass combustion flue gas, after dust removal, acid removal and denitrification, is discharged into the atmosphere through the exhaust gas emission module.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] This invention addresses the NOx and SOx emission problems of biomass boilers by injecting atomized alkaline solution into the superheater outlet flue using an alkaline injection system and atomizing injection device to remove acidic gases such as SO2, SO3, and HCl. The flue gas after acid removal is further treated by a high-temperature dust collector and then enters an SCR self-denitrification system. The system utilizes the NH3 released during biomass combustion to catalytically reduce NOx in the flue gas, thereby enhancing the self-denitrification of biomass combustion flue gas and achieving NOx removal.

[0021] Furthermore, this invention, through the combined use of an alkaline injection system, a dust removal system, and an SCR self-denitrification system, can effectively remove acidic gases and nitrogen oxides emitted from biomass combustion, reducing air pollutant emissions and meeting environmental protection requirements. The use of an economizer and air preheater can improve boiler thermal efficiency, reduce fuel consumption, increase fuel combustion efficiency, and save energy. This invention can achieve the synergistic removal of NOx and acidic gases (SOx and HCl) from biomass combustion flue gas, achieving ultra-low emissions of NOx, SOx, and HCl from biomass boilers. This invention achieves the goals of environmental protection, energy conservation, improved combustion efficiency, and comprehensive utilization of biomass energy, demonstrating significant economic and environmental benefits. Attached Figure Description

[0022] Figure 1 This is a flowchart of the deacidification, dust removal, and denitrification process of the present invention.

[0023] Figure 2 This is a diagram of the ultra-low emission boiler combustion system of the present invention.

[0024] In the diagram: 1 Furnace; 2 Cyclone Separator; 3 Superheater; 4 Flue Gas Composition Analysis Sensor; 5 Alkali Injection System; 6 Atomizing Injection Device; 7 High-Temperature Dust Collector; 8 Chimney; 9 Exhaust Fan; 10 Air Preheater; 11 Economizer; 12 SCR Self-Denitrification System; 13 Flue; 14 Return Material Channel. Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments. Example

[0026] This embodiment provides an ultra-low emission system for a biomass boiler with synergistic desulfurization and enhanced self-denitrification, including a combustion module, a dust removal, desulfurization, and denitrification module, and a tail gas emission module. The combustion module includes a boiler furnace 1 and a cyclone separator 2. The outlet of the furnace is connected to the inlet of the cyclone separator. Biomass fuel is fed into the furnace 1 for combustion, and the flue gas after combustion enters the cyclone separator. The bottom of the cyclone separator is also provided with a return channel 14, the end of which is connected to the inner cavity of the furnace. This allows unburned solid particles mixed in with the flue gas discharged from the furnace to return to the furnace for secondary combustion through the return channel, while the separated flue gas flows into the flue from the outlet of the cyclone separator.

[0027] A superheater 3 is also installed in the flue between the cyclone separator and the dust removal, acid removal and denitrification module to heat the high-temperature flue gas generated in the furnace and improve thermal efficiency. The dust removal, acid removal and denitrification module is located downstream of the superheater. A flue gas composition analysis sensor 4 is also installed in the flue downstream of the superheater 3. The dust removal, acid removal and denitrification module includes an alkaline injection system, a dust removal system and an SCR self-denitrification system. The alkaline injection system is connected to the atomizing injection device 6 inside the flue.

[0028] The emission concentrations of SO2, SO3, and HCl in the flue gas are monitored and measured by the flue gas composition analysis sensor 4, and the monitoring data is transmitted to the alkaline injection system 5. After receiving the emission concentration information of SO2, SO3, and HCl obtained by the flue gas composition analysis sensor 4, the alkaline injection system 5 delivers a certain amount of alkaline solution to the atomizing injection device 6 and controls the atomizing injection device 6 to spray into the flue. The atomizing injection device 6 atomizes and sprays the alkaline solution, increasing the contact area with the flue gas, thereby achieving the removal of acidic gases such as SOx and HCl in the biomass combustion flue gas in the flue and further improving the desulfurization efficiency.

[0029] The atomized alkaline solution can be an alkaline solution such as NaOH, KOH, or Ca(OH)2 with a concentration of 1% to 10%. After passing through the superheater, the flue gas temperature in the flue is 250 to 400°C. At this temperature, the atomized alkaline solution is sprayed into the flue to neutralize the acidic substances in the flue gas. The alkaline solution injection system 5 controls the amount of alkaline solution injected by the atomizing injection device 6 to maintain a molar ratio of alkaline substances to acidic gases in the flue gas, such as SO2, SO3, and HCl, within the range of 2:1 to 5:1. The specific ratio should be determined based on the specific boundary parameters such as the type of alkaline solution selected, the removal efficiency of acidic gases such as SO2 / SO3 / HCl, the temperature of the flue gas in the flue, and the length of the flue.

[0030] The dust removal system is located in the flue downstream of the alkaline solution injection system. In this embodiment, the dust removal system is a high-temperature dust collector 7, which uses a metal filter membrane or a ceramic fiber filter membrane to achieve high-temperature flue gas dust removal, that is, to remove solid particulate matter from the flue gas and ensure that the emitted flue gas meets ultra-low emission standards. The flue gas after dust removal by the high-temperature dust collector enters the SCR self-denitrification system 12.

[0031] The SCR self-denitrification system 12 utilizes the NH3 present in the biomass combustion flue gas to undergo a catalytic oxidation-reduction reaction with NOx in the flue gas, thereby achieving enhanced self-removal of NOx from the biomass combustion flue gas. At the same time, it reduces the NH3 concentration in the flue gas, inhibits the formation of ammonium bisulfate (ABS) and ammonium chloride (NH4Cl), and avoids ash accumulation, blockage, and corrosion in downstream equipment of the boiler.

[0032] The exhaust gas module includes a heat exchange system and a chimney 8. The heat exchange system includes an economizer 11, an air preheater 10, and an induced draft fan 9. The economizer 11, air preheater 10, and induced draft fan 9 are sequentially arranged in the downstream flue of the SCR self-denitrification system along the flue gas flow direction. The economizer transfers heat from the flue gas discharged from the boiler to the boiler feed water by exchanging heat, thereby reducing the temperature of the feed water, reducing the calorific value required by the boiler, and saving fuel.

[0033] The air preheater exchanges heat between the flue gas and air in the flue, transferring the heat from the flue gas to the air, which increases the temperature of the air during combustion and improves the combustion efficiency of the fuel. The induced draft fan is used to send air into the boiler furnace to provide the oxygen required for combustion and promote the combustion process.

[0034] By installing an economizer 11, an air preheater 10, and an induced draft fan 9 in the boiler flue, the boiler's thermal efficiency and combustion efficiency can be effectively improved, reducing fuel consumption and emissions. The flue ends in a chimney 8, and the biomass combustion flue gas, after dust removal, acid removal, and denitrification, is discharged into the atmosphere through the chimney after passing through a heat exchange system.

[0035] This invention provides a synergistic deacidification-enhanced self-denitrification ultra-low emission system for biomass boilers. It utilizes an alkaline injection system and an atomizing injection device to inject atomized alkaline solution into the superheater outlet flue, achieving the removal of acidic gases such as SO2, SO3, and HCl. The deacidified flue gas is further treated by a high-temperature dust collector and then enters the SCR self-denitrification system. Here, NH3 released during biomass combustion reacts with NOx in the flue gas via a catalytic reduction reaction, enhancing the self-denitrification of biomass combustion flue gas and achieving NOx removal. This invention enables the synergistic removal of NOx and acidic gases (SOx and HCl) from biomass combustion flue gas, achieving ultra-low emissions of NOx, SOx, and HCl from biomass boilers. Example

[0036] This embodiment provides a method for ultra-low emissions from biomass boilers using a synergistic desulfurization-enhanced self-denitrification system. The method utilizes the synergistic desulfurization-enhanced self-denitrification system for biomass boilers provided in Embodiment 1 above, and specifically includes the following steps:

[0037] First, biomass fuel is burned in the furnace 1. The flue gas after combustion enters the cyclone separator. The unburned solid particles mixed in the flue gas discharged from the furnace are returned to the furnace for secondary combustion through the return channel. The separated flue gas flows into the flue from the outlet of the cyclone separator.

[0038] After receiving the emission concentration information of SO2, SO3 and HCl in the flue gas obtained by the flue gas composition analysis sensor 4, the alkaline liquid injection system 5 delivers a certain amount of alkaline liquid to the atomizing injection device 6 and controls the atomizing injection device 6 to atomize and spray the alkaline liquid into the flue, thereby removing acidic gases such as SOx and HCl from the biomass combustion flue gas in the flue.

[0039] After acid removal, the flue gas is further treated by a high-temperature dust collector and then enters the SCR self-denitrification system. The system utilizes the NH3 released during biomass combustion to catalytically reduce NOx in the flue gas, enhancing the self-denitrification of the biomass combustion flue gas and achieving NOx removal. Finally, the flue gas, after dust removal, acid removal, and denitrification, is discharged into the atmosphere through heat exchange in the heat exchange system. This invention can be used to achieve synergistic acid removal and enhanced self-denitrification in biomass boilers, achieving ultra-low emissions of pollutants such as NOx, SOx, and HCl from the flue gas.

[0040] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomass boiler ultra-low emission system with synergistic deacidification and enhanced self-denitrification, comprising a combustion module, a dust removal, deacidification, and denitrification module, and a tail gas emission module, characterized in that: The combustion module includes a boiler furnace and a cyclone separator. The outlet of the furnace is connected to the inlet of the cyclone separator, and the flue gas after combustion in the furnace enters the cyclone separator. The bottom of the cyclone separator is also provided with a return channel, the end of which is connected to the inner cavity of the furnace. The dust removal, acid removal, and denitrification module is located in the flue between the combustion module and the exhaust gas emission module. It includes an alkaline injection system, a dust removal system, and an SCR self-denitrification system. A superheater is also installed intermittently in the flue between the cyclone separator and the dust removal, acid removal, and denitrification module to maintain the flue gas temperature at 250-400℃. After the biomass combustion flue gas from the combustion module is discharged into the flue, the alkaline injection system controls an atomizing injection device located in the flue to spray atomized alkaline solution into the superheater outlet flue, thereby removing acidic gases from the flue gas. The dust removal system is located between the alkaline injection system and the SCR self-denitrification system, achieving high-temperature dust removal of the flue gas. The SCR self-denitrification system is used to enhance the self-denitrification of the dust-removed biomass combustion flue gas. The exhaust gas emission module is connected to the flue gas outlet, and the biomass combustion flue gas after dust removal, acid removal and denitrification is discharged into the atmosphere through the exhaust gas emission module.

2. The biomass boiler ultra-low emission system with synergistic desulfurization and enhanced self-denitrification as described in claim 1, characterized in that: A flue gas composition analysis sensor is also installed in the downstream flue of the superheater.

3. The biomass boiler ultra-low emission system with synergistic desulfurization and enhanced self-denitrification as described in claim 1, characterized in that: The atomizing alkaline solution can be a NaOH, KOH, Ca(OH)2 or other alkaline solution with a concentration of 1% to 10%; and the amount of alkaline solution sprayed into the flue, the molar ratio of alkaline substances to acidic gases in the flue gas is controlled within the range of 2:1 to 5:

1.

4. The biomass boiler ultra-low emission system with synergistic desulfurization and enhanced self-denitrification as described in claim 1, characterized in that: The dust removal system is a high-temperature dust collector, which uses a metal filter membrane or a ceramic fiber filter membrane to achieve dust removal from high-temperature flue gas.

5. The biomass boiler ultra-low emission system with synergistic desulfurization and enhanced self-denitrification as described in claim 1, characterized in that: The exhaust gas emission module includes a heat exchange system and a chimney. The heat exchange system includes an economizer, an air preheater, and an induced draft fan, which are sequentially arranged in the downstream flue of the SCR self-denitrification system along the flue gas flow direction. The end of the flue is connected to the chimney.

6. A method for ultra-low emissions from a biomass boiler with synergistic desulfurization and enhanced self-denitrification, employing the synergistic desulfurization and enhanced self-denitrification biomass boiler ultra-low emission system according to any one of claims 1-5, characterized in that: Includes the following steps: S1. Biomass fuel is put into the furnace for combustion. The flue gas after combustion enters the cyclone separator. The unburned solid particles mixed in the flue gas discharged from the furnace are returned to the furnace for secondary combustion. The separated flue gas flows into the flue from the outlet of the cyclone separator. S2. After receiving the concentration information of pollutants in the flue gas, the alkaline liquid injection system controls the atomizing injection device to atomize and spray alkaline liquid into the flue, thereby removing acidic gases from the biomass combustion flue gas in the flue. S3. After the acid removal process, the flue gas enters the SCR denitrification system after being removed by the dust removal system to enhance the denitrification of the biomass combustion flue gas. S4. The biomass combustion flue gas, after dust removal, acid removal and denitrification, is discharged into the atmosphere through the exhaust gas emission module.

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