Biomass and garbage boiler efficient energy-saving type waste gas treatment system and treatment process

Abstract

The invention relates to the technical field of environment-friendly equipment, in particular to an efficient energy-saving type waste gas treatment system and process for a biomass and garbage boiler, and the treatment system comprises an air preheater, a dry desulphurization device, a dust remover, a low-temperature denitration device, a heat exchanger and a chimney which are sequentially connected at an outlet of the boiler. An inlet and an outlet of a first heat exchange channel of the heat exchanger are connected with a low-temperature denitration device and a chimney respectively, and an inlet and an outlet of a second heat exchange channel of the heat exchanger are connected with air and an air preheater respectively. Therefore, the temperature of waste gas in desulfurization, dust removal and denitration links is increased, and finally heat energy is recycled by the heat exchanger. The process is free of additional energy supplement, the emission temperature is reduced, the heat energy loss is less, the advantages of energy conservation and emission reduction are achieved, the denitration reaction temperature is increased, and the denitration efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection equipment, and in particular to a high-efficiency and energy-saving waste gas treatment system and treatment process for biomass and garbage boilers. Background Art

[0002] Biomass boiler is a type of boiler. A boiler that uses biomass energy as fuel is called a biomass boiler. A garbage boiler is a boiler that uses garbage as fuel. The flue gas after incineration of biomass boilers and garbage boilers has some common characteristics: the flue gas has high humidity and many particulates. The exhaust gas of the boiler needs to be treated before it can be discharged, including denitrification, dust removal, and desulfurization. In other boilers, the denitrification catalyst is placed behind the economizer of the boiler. However, due to the large amount of particulates in the flue gas of biomass boilers and garbage boilers, the catalyst is easily blocked. Therefore, denitrification is not suitable for arrangement upstream of exhaust gas treatment. However, if placed at the rear end of desulfurization and dust removal, the denitrification inlet temperature can only reach about 140°C, which is far lower than the optimal reaction temperature of 180°C for the denitrification low-temperature catalyst. The denitrification efficiency is reduced, and the exhaust gas temperature reaches about 130°C, energy is wasted, and it does not meet the requirements of energy conservation and emission reduction. Summary of the invention

[0003] The problem solved by the present invention is: in order to solve the problems of insufficient denitration temperature and heat energy waste in biomass and garbage boilers in the prior art, a high-efficiency and energy-saving waste gas treatment system and treatment process for biomass and garbage boilers are provided.

[0004] The present invention is implemented through the following technical scheme: a high-efficiency and energy-saving waste gas treatment system for biomass and garbage boilers, including an air preheater, a dry desulfurization device, a dust collector, a low-temperature denitrification device, a heat exchanger, and a chimney connected in sequence at the boiler outlet, the inlet and outlet of the first heat exchange channel of the heat exchanger are respectively connected to the low-temperature denitrification device and the chimney, and the inlet and outlet of the second heat exchange channel of the heat exchanger are respectively connected to the air and the air preheater.

[0005] Furthermore, a first fan is provided in one of the multiple flues between the air preheater, the dry desulfurization device, the dust collector, the low-temperature denitrification device, the heat exchanger, and the chimney.

[0006] Furthermore, a second fan is provided at the front end or the rear end of the heat exchanger.

[0007] Furthermore, the dry desulfurization device is a calcium-based desulfurization or a sodium-based desulfurization.

[0008] Furthermore, the dust collector is a bag dust collector.

[0009] Furthermore, the low-temperature denitration device is a low-temperature SCR denitration device.

[0010] Another aspect of the present invention provides a treatment process for a high-efficiency and energy-saving waste gas treatment system for biomass and garbage boilers: the air required for boiler combustion is first heat exchanged in the heat exchanger at the rear end of the low-temperature denitrification device, and then the temperature entering the air preheater is increased, and the temperature drop of the waste gas in the air preheater is reduced, thereby increasing the waste gas temperature in the desulfurization, dust removal and denitrification links, and finally the heat energy is recovered by the heat exchanger.

[0011] Furthermore, the air required for boiler combustion is first heated to 90℃-100℃ through a heat exchanger, then enters an air preheater for heat exchange with exhaust gas at 250℃-260℃, and finally enters the boiler. The temperature of the boiler exhaust gas is 250℃-260℃ after passing through the economizer. After passing through the air preheater, it is heat exchanged with air at 90℃-100℃, and the temperature is reduced to 190℃-200℃. The exhaust gas enters a dry desulfurization device for calcium-based desulfurization or sodium-based desulfurization. The dust collector collects the desulfurizer, desulfurization reactants, and particulate matter in the flue gas. The exhaust gas has a temperature of 180℃-185℃ after coming out of the dust collector, and enters a low-temperature denitrification device for denitrification reaction. The clean exhaust gas after the reaction is heated to 50℃-60℃ through a heat exchanger and is finally discharged from the chimney.

[0012] The beneficial effects of the present invention are:

[0013] The present invention recovers heat energy through a heat exchanger, heats the air required for boiler combustion to 100°C, reduces the temperature drop of the exhaust gas in the air preheater, thereby increasing the exhaust gas temperature in the desulfurization, dust removal and denitration links, and finally recovers heat energy through a heat exchanger. There is no additional energy supplement in the process, the emission temperature is reduced, the heat energy loss is small, it has the advantages of energy saving and emission reduction, and it also increases the reaction temperature of denitration and improves the denitration efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A high-efficiency and energy-saving waste gas treatment system for biomass and garbage boilers according to the present invention;

[0015] Figure 2 It is the processing technology in the prior art mentioned in the embodiment;

[0016] Figure 3 The invention discloses a high-efficiency and energy-saving waste gas treatment process for biomass and garbage boilers.

[0017] In the figure: 1 boiler; 2 air preheater; 3 dry desulfurization device; 4 dust collector; 5 low-temperature denitrification device; 6 heat exchanger; 7 chimney; 8 first fan; 9 second fan; 10 heater. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the prior art, Figure 2 As shown, the biomass boiler 1 or the garbage boiler 1 is generally connected to a dry desulfurization device 3, a dust collector 4, a heater 10, a low-temperature denitrification device 5, a heat exchanger 6, and a chimney 7. The exhaust gas is generally 250°C-260°C after passing through the economizer. After passing through the air preheater 2, it is heat exchanged with air at 20°C and the temperature is reduced to 140°C-150°C. After desulfurization and dust removal, the flue gas temperature is reduced to 130°C-120°C, and then it is heated by the heater 10 to about 180°C, and enters the low-temperature denitrification device 5 for reaction. The clean flue gas after the reaction is discharged from the chimney 7, and the discharge temperature reaches 120°C-130°C. The heater 10 is needed in the whole process for additional energy supplement, and the discharge temperature is too high, resulting in a large waste of heat energy.

[0020] Embodiments of the present invention include Figure 1 As shown, a high-efficiency and energy-saving waste gas treatment system for biomass and garbage boilers includes an air preheater 2, a dry desulfurization device 3, a dust collector 4, a low-temperature denitrification device 5, a heat exchanger 6, and a chimney 7 connected in sequence at the outlet of the boiler 1. The inlet and outlet of the first heat exchange channel of the heat exchanger 6 are respectively connected to the low-temperature denitrification device 5 and the chimney 7, and the inlet and outlet of the second heat exchange channel of the heat exchanger 6 are respectively connected to the air and the air preheater 2. The air required for the combustion of the boiler 1 is first heat-exchanged by the heat exchanger 6 at the rear end of the low-temperature denitrification device 5, and the temperature of the air entering the air preheater 2 is increased, and the temperature drop of the waste gas in the air preheater 2 is reduced, thereby increasing the temperature of the waste gas in the desulfurization, dust removal, and denitrification links, and finally the heat energy is recovered by the heat exchanger 6. There is no energy supplement in the process, and the emission temperature is reduced, the heat energy loss is less, and the reaction temperature of denitrification is increased, and the denitrification efficiency is improved.

[0021] In actual applications, a first fan 8 is provided at one of the multiple flues between the air preheater 2, the dry desulfurization device 3, the dust collector 4, the low-temperature denitrification device 5, the heat exchanger 6, and the chimney 7. The first fan 8 is arranged according to actual needs. In this embodiment, the first fan 8 is arranged behind the heat exchanger 6.

[0022] In practical applications, a second fan 9 is provided at the front end or rear end of the heat exchanger 6 . The second fan 9 is arranged according to actual needs. In this embodiment, the second fan 9 is arranged between the air preheater 2 and the heat exchanger 6 .

[0023] In practical applications, the dry desulfurization device 3 is a calcium-based desulfurization or a sodium-based desulfurization. Both the calcium-based desulfurization and the sodium-based desulfurization can meet the desulfurization requirements of the present invention, and the sodium-based desulfurization has a higher desulfurization efficiency.

[0024] In practical applications, the dust collector 4 is a bag dust collector 4 .

[0025] In practical applications, the low-temperature denitrification device 5 is a low-temperature SCR denitrification device, which measures the flue gas flow rate, temperature, NOx concentration, pressure, target denitrification rate, etc. to accurately measure the amount of reducing agent injection. Nitrogen oxides (NOx) react with the reducing agent (ammonia or urea) under the action of the catalyst to generate harmless nitrogen and water.

[0026] Another aspect of the present invention provides a treatment process for a biomass and garbage boiler high-efficiency energy-saving waste gas treatment system, such as Figure 3 As shown: the air required for combustion of the boiler 1 is first heat exchanged by the heat exchanger 6 at the rear end of the low-temperature denitration device 5, and the temperature entering the air preheater 2 is increased, and the temperature drop of the exhaust gas in the air preheater 2 is reduced, thereby increasing the exhaust gas temperature in the desulfurization, dust removal and denitration links, and finally recovering heat energy by the heat exchanger 6. There is no energy supplement in the process, and the emission temperature is reduced, the heat energy loss is small, and the reaction temperature of denitration is increased, thereby improving the denitration efficiency.

[0027] In practical applications, the air required for combustion in boiler 1 is first heated to 90°C-100°C through heat exchanger 6, then enters air preheater 2 for heat exchange with exhaust gas at 250°C-260°C, and finally enters boiler 1. The exhaust gas from boiler 1 has a temperature of 250°C-260°C after passing through economizer. After passing through air preheater 2, it is heat exchanged with air at 90°C-100°C, and the temperature is reduced to 190°C-200°C. The exhaust gas enters dry desulfurization device 3 for calcium-based desulfurization or sodium-based desulfurization. Dust collector 4 collects desulfurizer, desulfurization reactant, and particulate matter in flue gas. The exhaust gas has a temperature of 180°C-185°C after exiting dust collector 4, and enters low-temperature denitrification device 5 for denitrification reaction. The clean exhaust gas after the reaction is heated to 50°C-60°C through heat exchanger 6, and finally discharged from chimney 7.

[0028] In summary, the high-efficiency and energy-saving waste gas treatment system for biomass and garbage boilers described in the present invention reduces energy consumption, improves denitrification efficiency, and achieves energy conservation and emission reduction.

[0029] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above implementation is only to illustrate the technical concept and features of the present invention, and its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and it cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A biomass and garbage boiler high-efficiency energy-saving waste gas treatment system, characterized by: It includes an air preheater, a dry desulfurization device, a dust collector, a low-temperature denitrification device, a heat exchanger, and a chimney which are connected in sequence at the boiler outlet. The inlet and outlet of the first heat exchange channel of the heat exchanger are respectively connected to the low-temperature denitrification device and the chimney, and the inlet and outlet of the second heat exchange channel of the heat exchanger are respectively connected to the air and the air preheater.

2. A biomass and garbage boiler high-efficiency energy-saving waste gas treatment system according to claim 1, characterized in that: A first fan is provided in one of the multiple flues between the air preheater, the dry desulfurization device, the dust collector, the low-temperature denitration device, the heat exchanger, and the chimney.

3. A biomass and garbage boiler high-efficiency energy-saving waste gas treatment system according to claim 1, characterized in that: A second fan is arranged at the front end or the rear end of the heat exchanger.

4. A biomass and garbage boiler high-efficiency energy-saving waste gas treatment system according to claim 1, characterized in that: The dry desulfurization device is calcium-based desulfurization or sodium-based desulfurization.

5. The high-efficiency and energy-saving waste gas treatment system for biomass and garbage boilers according to claim 1 is characterized by: The dust collector is a bag dust collector.

6. The high-efficiency and energy-saving waste gas treatment system for biomass and garbage boilers according to claim 1 is characterized by: The low-temperature denitration device is a low-temperature SCR denitration device.

7. The treatment process of a biomass and garbage boiler high-efficiency energy-saving waste gas treatment system according to claim 1 is characterized by: The air required for boiler combustion is first heated by the heat exchanger at the rear end of the low-temperature denitrification device, which increases the temperature entering the air preheater and reduces the temperature drop of the exhaust gas in the air preheater, thereby increasing the exhaust gas temperature in the desulfurization, dust removal and denitrification links, and finally the heat energy is recovered by the heat exchanger.

8. The treatment process of a biomass and garbage boiler high-efficiency energy-saving waste gas treatment system according to claim 7 is characterized by: The air required for boiler combustion is first heated to 90℃-100℃ through a heat exchanger, then enters the air preheater for heat exchange with exhaust gas at 250℃-260℃, and finally enters the boiler. The temperature of the boiler exhaust gas is 250℃-260℃ after passing through the economizer. After passing through the air preheater, it is heat exchanged with air at 90℃-100℃, and the temperature is reduced to 190℃-200℃. The exhaust gas enters the dry desulfurization device for calcium-based desulfurization or sodium-based desulfurization. The dust collector collects the desulfurizer, desulfurization reactants, and particulate matter in the flue gas. The exhaust gas has a temperature of 180℃-185℃ after coming out of the dust collector, and enters the low-temperature denitrification device for denitrification reaction. The clean exhaust gas after the reaction is heated to 50℃-60℃ through a heat exchanger and finally discharged from the chimney.

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