Semi-dry desulfurization flue gas deep purification and waste heat recovery co-processing system

Abstract

The utility model belongs to the technical field of flue gas purification, and particularly relates to a semi-dry desulfurization flue gas deep purification and waste heat recovery co-processing system which comprises a flue gas purification absorption tower, a gas rising cap is arranged in the flue gas purification absorption tower and divides the flue gas purification absorption tower into two sections, the lower section is a flue gas purification section, and the upper section is a flue gas waste heat recovery section. And the upper section is a waste heat recovery section. And two functions of deep purification of flue gas and waste heat recovery can be realized. And meanwhile, the system is coupled with a semi-dry desulfurization process, after condensed water in the flue gas is treated by a water treatment device, clean water is used as heat supply network replenishing water or water for other processes, wastewater is pumped to a semi-dry desulfurization pulping system, and the technology does not generate extra wastewater.

Description

A semi-dry flue gas deep purification and waste heat recovery synergistic treatment system Technical Field

[0001] This utility model belongs to the field of flue gas purification technology, specifically relating to a semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system. Background Technology

[0002] In recent years, energy shortages and environmental protection have attracted widespread attention. To reduce reliance on traditional high-pollution, high-emission energy sources (such as coal and oil), and to improve and adjust the energy structure, developing renewable energy is of great significance for environmental protection and sustainable economic and social development. Waste incineration and biomass power generation are effective ways to convert waste into energy and are one of the pathways to achieving energy recycling. This approach not only reduces dependence on fossil fuels but also effectively addresses the problems of waste and garbage disposal.

[0003] Biomass power plants and waste incineration power plants generally use semi-dry desulfurization during operation (a process that combines the advantages of wet and dry desulfurization technologies. It mainly uses lime or limestone as a desulfurizing agent, which reacts chemically with sulfur dioxide in the flue gas in a semi-dry state to remove sulfides from the flue gas). After desulfurization, the high-temperature flue gas at around 80-150°C is directly discharged into the atmosphere, resulting in heat waste. This heat can account for more than 15% of the total calorific value of fuel combustion.

[0004] Meanwhile, the incineration of biomass fuels and waste generates a large amount of harmful gases, such as sulfur dioxide, nitrogen oxides, and carbon monoxide. Because biomass power plants and waste-to-energy plants conventionally use semi-dry desulfurization methods, soluble salts, water-soluble gaseous pollutants (such as HCl and HF), and some organic matter in the flue gas cannot be effectively removed. These pollutants are major sources of air pollution. Therefore, how to simultaneously purify the flue gas after semi-dry desulfurization in biomass power plants and waste-to-energy plants while recovering waste heat is a crucial challenge that urgently needs to be addressed to achieve energy recycling and energy conservation and emission reduction. Summary of the Invention

[0005] The purpose of this invention is to provide a semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system, which can simultaneously achieve two functions: deep flue gas purification and waste heat recovery, without generating additional wastewater or overall power consumption.

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0007] This utility model provides a semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system, including a flue gas purification absorption tower. The flue gas purification absorption tower is equipped with a gas lifting cap, which divides the flue gas purification absorption tower into two sections, wherein the lower section is the flue gas purification section and the upper section is the waste heat recovery section.

[0008] As a further technical solution, the flue gas purification section includes an inlet for semi-dry desulfurized flue gas, a second spray layer, and a purification spray pump; wherein, the inlet for semi-dry desulfurized flue gas is located on the side wall of the flue gas purification section, the second spray layer is located above the inlet for semi-dry desulfurized flue gas, and the purification spray pump is located at the bottom of the flue gas purification section and connected to the second spray layer.

[0009] As a further technical solution, the waste heat recovery section includes a first spray layer and a packing layer, wherein the first spray layer is disposed in the upper part of the waste heat recovery section and the packing layer is disposed in the lower part of the waste heat recovery section.

[0010] As a further technical solution, a high-temperature waste water outlet is provided on the side wall of the tower plate where the gas lifting cap is located; the high-temperature waste water outlet is connected to the waste water circulation tank;

[0011] The flue gas purification and absorption tower is equipped with a flue gas exhaust duct at the top, which is connected to the chimney.

[0012] As a further technical solution, an absorption heat pump is also included, which is equipped with a high-temperature waste water inlet and a low-temperature waste water outlet; the waste water circulation tank is connected to the high-temperature waste water inlet of the absorption heat pump through a waste water circulation pump.

[0013] As a further technical solution, the low-temperature waste water outlet of the absorption heat pump is connected to the first spray layer through a pipe and a liquid level control valve is provided on the pipe. The liquid level control valve is interlocked with the waste water circulation tank.

[0014] As a further technical solution, the absorption heat pump is equipped with a heating network water inlet and a heating network water outlet.

[0015] As a further technical solution, it also includes an alkali tank, which is an integral structure with the waste hot water circulation tank; the bottom of the alkali tank is equipped with an alkali pump;

[0016] The alkali pump is connected to a three-way pipe, and the alkali solution is added to the flue gas purification section and the waste heat recovery section of the flue gas purification absorption tower through the three-way pipe.

[0017] As a further technical solution, the bottom of the flue gas purification absorption tower is provided with a wastewater drain pipe, which is connected to a wastewater treatment device, and a wastewater discharge pump is provided on the wastewater drain pipe; the clean water treated by the wastewater treatment device is connected to the heating network water supply port.

[0018] As a further technical solution, the wastewater treatment device is connected to a concentrate tank, the concentrate tank is connected to a concentrate discharge pump, and the concentrate discharge pump is connected to a desulfurization pulping system.

[0019] The beneficial effects of the above-described embodiments of this utility model are as follows:

[0020] (1) The flue gas purification absorption tower in this utility model is divided into upper and lower parts, which can realize two functions: deep purification of flue gas and waste heat recovery.

[0021] (2) In the system-coupled semi-dry desulfurization process of this utility model, the condensate in the flue gas is treated by a wastewater treatment device to obtain clean water, which is used for heating network makeup water or other process water. The concentrated water is pumped to the semi-dry desulfurization pulping system, and no additional wastewater is generated.

[0022] (3) The waste heat recovery module of the flue gas purification absorption tower in this utility model is equipped with a packing layer to enhance the contact area between flue gas and spray liquid, reduce the liquid-gas ratio, and reduce the power consumption of the circulating pump.

[0023] (4) The integrated design of the waste water circulation tank and the alkali tank in this utility model reduces the footprint and lowers the manufacturing cost. Attached Figure Description

[0024] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0025] Figure 1 is an overall structural diagram of the semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system of this utility model.

[0026] The diagram is for illustrative purposes only.

[0027] The system includes: flue gas purification absorption tower 1, first spray layer 101, packing layer 102, air lifting cap 103, second spray layer 104, purification spray pump 2, waste hot water circulation tank 301, alkali tank 302, waste hot water circulation pump 4, absorption heat pump 5, liquid level control valve 6, alkali addition pump 7, first alkali control valve 801, second alkali control valve 802, wastewater discharge pump 9, wastewater treatment device 10, concentrated water tank 11, and concentrated water discharge pump 12. Detailed Implementation

[0028] It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0029] Example 1

[0030] In a typical embodiment of this utility model, a semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system is provided, as shown in Figure 1. It includes a flue gas purification absorption tower 1, within which a riser cap 103 (existing structure, DN300 from Hebei Manji Technology Fiberglass Co., Ltd.) is installed. The riser cap 103 divides the flue gas purification absorption tower 1 into two sections: a lower section for flue gas purification and an upper section for waste heat recovery. The riser cap 103 is used to guide the clean, saturated flue gas upwards into the waste heat recovery section. The flue gas purification section removes pollutants such as SO2, HCl, and HF from the semi-dry desulfurization flue gas, making the flue gas clean and saturated. The waste heat recovery section recovers waste heat from the clean, saturated flue gas, forming low-temperature clean flue gas.

[0031] The flue gas purification section includes an inlet for semi-dry desulfurization flue gas, a second spray layer 104, and a purification spray pump 2. The inlet for semi-dry desulfurization flue gas is located on the side wall of the purification section. The second spray layer 104 is located above the inlet, and the purification spray pump 2 is located at the bottom of the purification section and connected to the second spray layer 104. The inlet for semi-dry desulfurization flue gas is used to introduce the flue gas into the purification section for purification. The second spray layer 104 is used to spray circulating liquid to remove pollutants such as SO2, HCl, and HF from the flue gas discharged from the semi-dry desulfurization process, making the flue gas clean and saturated. The purification spray pump 2 is used to transport the circulating liquid from the bottom of the purification section to the second spray layer 104, thereby achieving the recycling of the circulating liquid.

[0032] The waste heat recovery section includes a first spray layer 101 and a packing layer 102 (existing packing, packing produced by Jiangxi Pingxiang Dier Chemical Packing Co., Ltd. can be used). The first spray layer 101 is located at the upper part of the waste heat recovery section, and the packing layer 102 is located at the lower part of the waste heat recovery section. The first spray layer 101 is used to spray low-temperature waste hot water to cool the clean and saturated flue gas. The cooled flue gas is discharged from the chimney connected to the exhaust duct at the top of the flue gas purification absorption tower 1. The packing layer 102 is used to allow the low-temperature waste hot water to fully contact and exchange heat with the clean and saturated flue gas to generate high-temperature waste hot water. The high-temperature waste hot water is discharged from the high-temperature waste hot water outlet located at the tower plate where the riser cap 103 is located, and will not fall into the flue gas purification section at the bottom of the flue gas purification absorption tower (1).

[0033] The high-temperature waste water outlet is connected to the waste water circulation tank 301, which stores the high-temperature waste water. The absorption heat pump 5 has a high-temperature waste water inlet and a low-temperature waste water outlet. The waste water circulation tank 301 is connected to the high-temperature waste water inlet of the absorption heat pump 5 via a waste water circulation pump 4. The waste water circulation pump 4 transports the high-temperature waste water from the waste water circulation tank 301 to the absorption heat pump 5. The low-temperature waste water outlet of the absorption heat pump 5 is connected to the first spray layer 101 via a pipe, thereby reducing the temperature of the clean, saturated flue gas to below 30°C before it enters the chimney for discharge, achieving continuous circulation.

[0034] The absorption heat pump 5 is used to absorb the heat of high-temperature waste water, thereby generating low-temperature waste water and transferring the heat to the heating network water or other low-temperature cold source water. For example, the absorption heat pump 5 is equipped with a heating network water inlet and a heating network water outlet. The heating network water inlet is used to transport low-temperature heating network water into the absorption heat pump 5, and the heating network water outlet is used to transport the heated heating network water out of the absorption heat pump 5, thereby realizing the heating of the heating network water.

[0035] The low-temperature waste water outlet of the absorption heat pump 5 is also connected to the low-temperature waste water inlet at the top of the flue gas purification section via a pipe, and a level control valve 6 is installed on this pipe to replenish water to the flue gas purification section, diluting the circulating liquid in the lower section and keeping the circulating liquid in a highly efficient absorption state. The level control valve 6 is interlocked with the waste water circulation tank 301 to ensure the stability of the liquid level in the waste water circulation tank 301. This is because a large amount of water will condense down in the flue gas purification section, and some water will evaporate in the lower waste heat recovery section due to the high flue gas temperature. Therefore, the water condensed in the waste heat recovery section needs to be replenished to the flue gas purification section. The level control valve 6 is interlocked with the liquid level in the waste water circulation tank 301, and a level gauge can also be installed on the waste water circulation tank 301 to control the liquid level in the waste water circulation tank 301 to maintain a stable level. The replenishment water can be directly added to the lower waste heat recovery section. Since the second spray layer 104 is pressurized, it is inconvenient to directly connect the replenishment water in the level control valve 6 to the second spray layer 104.

[0036] An alkali tank 302 is also provided. The alkali tank 302 and the waste hot water circulation tank 301 are integrated into one structure, reducing the floor space. An alkali pump 7 is provided at the bottom of the alkali tank 302. The alkali pump 7 is used to draw alkali from the alkali tank 302 and add the alkali to the flue gas purification absorption tower 1 through a three-way pipe. This is because the upper and lower sections of the flue gas purification absorption tower 1 need to control the pH value separately. If the pH value of the flue gas purification section is adjusted by the water in the waste hot water circulation tank 301, the pH value needs to be adjusted to be higher than 7 in order to improve the pH value of the flue gas purification section. By adopting the method of separately adding alkali, it is only necessary to adjust the pH of the upper and lower sections of the flue gas purification absorption tower 1 to 6-7 respectively to meet the requirements for normal operation. Specifically: A first alkali control valve 801 is installed on the pipe leading to the waste hot water circulation tank 301 in the three-way pipeline. The alkali solution in the waste hot water circulation tank 301, cooled by the absorption heat pump 5, returns to the upper flue gas purification section of the flue gas purification absorption tower 1. A second alkali control valve 802 is installed on the pipe leading to the flue gas purification section in the three-way pipeline. The pipe leading to the flue gas purification section in the three-way pipeline is connected to the pipe connecting the purification spray pump 2 and the second spray layer 104, thereby mixing the alkali solution with the circulating water before adding it to the second spray layer 104, maintaining the pH value of the circulating water, and ensuring that the circulating water can deeply remove pollutants such as SO2 from the flue gas. To maintain the alkali solution volume in the alkali solution tank 302, an alkali replenishment port is provided at the top of the alkali solution tank 302, thereby ensuring a stable supply of alkali solution to the alkali solution tank 302.

[0037] The bottom of the flue gas purification absorption tower 1 is equipped with a wastewater drain pipe, which is used to discharge the hot water generated in the flue gas purification absorption tower 1. The wastewater discharge pipe is connected to the wastewater treatment device 10, and a wastewater discharge pump 9 is installed on the wastewater discharge pipe. The wastewater discharge pump 9 is used to transport the wastewater generated by the flue gas purification absorption tower 1 to the wastewater treatment device 10 for centralized treatment. The wastewater treatment device 10 (an existing device, which can be a reverse osmosis membrane water treatment device) is used to centrally treat the wastewater, producing clean water and concentrated water (water with high salt content or high molecular weight). The clean water treated by the wastewater treatment device 10 is used for heating network makeup water (to maintain stable water flow and pressure in the heating network and ensure the efficient and stable operation of the heating system). The wastewater treatment device 10 is connected to a concentrated water tank 11, which is used to collect the concentrated water generated by the wastewater treatment device 10 during the wastewater treatment process. The concentrate tank 11 is connected to the concentrate discharge pump 12, which is used to transport the concentrate in the concentrate tank 11 to the desulfurization pulping system (using an existing system, including a limestone pulping pool or limestone pulping tank, etc.) for centralized treatment without generating additional wastewater.

[0038] The working principle of the semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system provided by this utility model is as follows:

[0039] The semi-dry desulfurization flue gas enters the flue gas purification section of the lower section of the flue gas purification absorption tower 1 through the inlet of the semi-dry desulfurization flue gas in the flue gas purification section. The circulating liquid at the bottom of the flue gas purification section is pumped by the purification spray pump 2 into the second spray layer 104 set at the top of the flue gas purification section for spraying, removing pollutants such as SO2, HCl, and HF from the flue gas, and turning the flue gas into a clean and saturated state. The clean and saturated flue gas enters the waste heat recovery section in the upper section of the flue gas purification absorption tower 1 through the riser cap 103. The clean and saturated flue gas comes into direct contact with the low-temperature waste water sprayed by the first spray layer 101. The low-temperature waste water and the flue gas undergo sufficient heat exchange in the packing layer 2 set in the waste heat recovery section to form clean low-temperature flue gas and high-temperature waste water. The clean low-temperature flue gas is discharged from the chimney connected to the flue duct set at the top of the flue gas purification absorption tower 1. The high-temperature waste water falls into the tower plate where the riser cap 103 is located and does not fall into the flue gas purification section of the lower section of the flue gas purification absorption tower 1.

[0040] High-temperature waste water flows through a gravity pipe to the waste water circulation tank 301. The waste water circulation pump 4 pumps the high-temperature waste water from the waste water circulation tank 301 to the absorption heat pump 5 for heat release and cooling. After absorbing the heat from the high-temperature waste water, the absorption heat pump 5 forms low-temperature waste water and transfers the heat to the heating network water or other low-temperature cold source water.

[0041] The low-temperature waste water cooled by the absorption heat pump 5 returns to the upper spray layer 101 of the flue gas purification absorption tower 1 for further spraying, reducing the flue gas temperature to below 30°C before being discharged through the chimney, in a continuous cycle. The low-temperature waste water cooled by the absorption heat pump 5 is then replenished into the lower flue gas purification section of the flue gas purification absorption tower 1 through the level control valve 6. The level control valve 6 is interlocked with the waste water circulation tank 301 to ensure a stable level in the waste water circulation tank 301.

[0042] Since some pollutants such as SO2 still exist in the flue gas, the low-temperature waste water will gradually absorb the SO2 in the flue gas, causing the pH to continuously decrease. Therefore, it is necessary to periodically add some alkaline solution into the flue gas purification spray tower 1 to maintain the pH value of the circulating water in the flue gas purification system. The alkaline pump 7 draws alkaline solution from the alkaline solution tank 302 and adds it to the lower spray layer of the flue gas purification absorption tower 1 and the waste water circulation tank 301 through the first alkaline solution control valve 801 and the second alkaline solution control valve 802 to maintain the pH value of the low-temperature waste water and ensure that the circulating water can deeply remove pollutants such as SO2 from the flue gas.

[0043] Because the flue gas temperature is reduced by the waste heat recovery section at the top of the flue gas purification absorption tower 1, a large amount of saturated water vapor in the flue gas will condense. The condensed flue gas condensate is then replenished into the flue gas purification section through the level control valve 6. Since the circulating water in the lower section of the purification process absorbs SO2 and NO from the flue gas... XThe condensate from the upper waste heat recovery section of flue gas purification absorption tower 1, as well as pollutants such as soluble salts and water-soluble gaseous pollutants (such as HCl and HF), has a relatively good water quality. When added to the lower flue gas purification section of flue gas purification absorption tower 1, it can dilute the circulating liquid in the lower part and keep the circulating liquid in a highly efficient absorption state.

[0044] The excess flue gas condensate in the purification module is of poor quality and is pumped into the wastewater treatment device 10 by the wastewater discharge pump 9 for treatment. The treated clean water is then added to the heating network as heating network makeup water. The resulting concentrated water is pumped into the concentrated water tank 11 and then pumped by the concentrated water discharge pump 12 to the semi-dry desulfurization pulping system for reuse. This system does not generate additional wastewater.

[0045] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system, characterized in that, The system includes a flue gas purification and absorption tower, which is equipped with a gas lifting cap that divides the flue gas purification and absorption tower into two sections: a lower section for flue gas purification and an upper section for waste heat recovery.

2. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 1, characterized in that, The flue gas purification section includes an inlet for semi-dry desulfurization flue gas, a second spray layer, and a purification spray pump; wherein, the inlet for semi-dry desulfurization flue gas is located on the side wall of the flue gas purification section, the second spray layer is located above the inlet for semi-dry desulfurization flue gas, and the purification spray pump is located at the bottom of the flue gas purification section and connected to the second spray layer.

3. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 1, characterized in that, The waste heat recovery section includes a first spray layer and a packing layer. The first spray layer is disposed at the upper part of the waste heat recovery section, and the packing layer is disposed at the lower part of the waste heat recovery section.

4. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 1, characterized in that, The side wall of the tower plate where the gas lifting cap is located is provided with a high-temperature waste water outlet; the high-temperature waste water outlet is connected to the waste water circulation tank; the top of the flue gas purification and absorption tower is provided with a flue, which is connected to the chimney.

5. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 4, characterized in that, It also includes an absorption heat pump, which is equipped with a high-temperature waste water inlet and a low-temperature waste water outlet; the waste water circulation tank is connected to the high-temperature waste water inlet of the absorption heat pump through a waste water circulation pump.

6. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 5, characterized in that, The low-temperature waste water outlet of the absorption heat pump is connected to the first spray layer through a pipe, and a liquid level control valve is provided on the pipe. The liquid level control valve is interlocked with the waste water circulation tank.

7. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 5, characterized in that, The absorption heat pump is equipped with a heating network water inlet and a heating network water outlet.

8. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 4, characterized in that, It also includes an alkali tank, which is an integral structure with the waste heat circulation tank; the bottom of the alkali tank is equipped with an alkali pump; the alkali pump is connected to a three-way pipe, and the alkali is added to the flue gas purification section and the waste heat recovery section in the flue gas purification absorption tower through the three-way pipe.

9. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 1, characterized in that, The bottom of the flue gas purification and absorption tower is equipped with a wastewater drain pipe, which is connected to a wastewater treatment device. A wastewater discharge pump is installed on the wastewater drain pipe. The clean water treated by the wastewater treatment device is connected to the heating network water supply port.

10. The semi-dry desulfurization flue gas deep purification and waste heat recovery synergistic treatment system according to claim 9, characterized in that, The wastewater treatment device is connected to the concentrate tank, the concentrate tank is connected to the concentrate discharge pump, and the concentrate discharge pump is connected to the desulfurization pulping system.

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