A scrubbing column for recovering gas-liquid residual heat

Abstract

This application discloses a scrubbing tower for recovering waste heat from gas and liquid processes, comprising: a tower body, with a slurry pool at the bottom and a scrubbing zone and a drying zone above the slurry pool, the flue gas inlet being located on the tower wall of the scrubbing zone and the top of the tower body; an inclined plate heat exchanger, disposed within the slurry pool and below the liquid surface, comprising several equally spaced and inclined hollow heat exchange plates; an oxidation blower, the oxidation air outlet of which is connected to the slurry pool via a duct, with the inlet located below the inclined plate heat exchanger; and a vertical plate heat exchanger, disposed in the scrubbing zone and between the liquid surface and the flue gas inlet within the slurry pool, connected in series with the inclined plate heat exchanger, comprising several equally spaced and vertically installed hollow heat exchange plates. The waste heat recovered by this scrubbing tower can be used to heat the raw water used for desalination in the water treatment workshop of a power plant, reducing the energy consumption for boiler feedwater heating in the power plant, and can also be used to heat the domestic shower water in the power plant, realizing the recovery and utilization of waste heat from gas and liquid processes in the scrubbing tower.

Description

Technical Field

[0001] This application relates to the field of industrial waste heat recovery technology, specifically to a scrubbing tower for recovering gas-liquid waste heat. Background Technology

[0002] Driven by global energy shortages and the "dual carbon" target, energy conservation and emission reduction in the industrial sector have become important development directions. Statistics show that industrial energy consumption accounts for more than 40% of global energy consumption, with approximately 50% of this energy emitted as waste heat. In particular, the chemical, metallurgical, and power industries generate large amounts of low- to medium-temperature waste heat (80–200℃) during production processes, but due to limitations in recovery technology, the utilization rate is less than 30%. As a core piece of equipment for industrial waste gas treatment, scrubbing towers generate a large amount of vapor-liquid mixed waste heat in processes such as wet desulfurization, dust removal, and gas purification. Direct emission of this heat not only wastes energy but also exacerbates thermal pollution. Therefore, developing efficient waste heat recovery technology for scrubbing towers is of great significance for improving energy efficiency and reducing carbon emissions.

[0003] The waste heat from scrubbing towers mainly comes from two sources: sensible heat released when high-temperature exhaust gas comes into contact with the scrubbing liquid, and latent heat of water vapor condensation. For example, in a wet desulfurization system of a coal-fired power plant, the flue gas temperature drops from 120–150°C to 50–60°C, during which approximately 30% of the heat energy is transferred to the circulating slurry, forming a two-phase flow of vapor and liquid. This type of waste heat has the following characteristics: narrow temperature range: mostly medium-low temperature heat sources (60–90°C), making traditional heat pumps or heat exchangers uneconomical to recover; strong corrosiveness: containing acidic components such as sulfur and chlorine, as well as particulate matter, easily causing scaling and corrosion of equipment; heat-mass coupling: heat exists in both sensible and latent heat forms, requiring simultaneous recovery.

[0004] Existing technologies such as single-plate heat exchangers and flash recovery suffer from problems such as low heat transfer efficiency and poor adaptability, and innovative solutions are urgently needed. Utility Model Content

[0005] This application provides a scrubbing tower for recovering waste heat from gas and liquid, which has high heat transfer efficiency and strong adaptability, and can efficiently recover waste heat from gas and liquid in the scrubbing tower.

[0006] A scrubbing tower for recovering waste heat from gas and liquid, comprising:

[0007] The tower body has a slurry pool at the bottom, and above the slurry pool are the washing zone and the drying zone. The flue gas inlet is located on the tower wall of the washing zone, and the flue gas inlet is located at the top of the tower body.

[0008] An inclined plate heat exchanger is installed in the slurry pool and located below the liquid surface. It includes several hollow heat exchange plates that are equally spaced and installed at an incline. The hollow heat exchange plates have channels for the flow of heat exchange medium.

[0009] An oxidation blower, the oxidation air outlet of which is connected to the slurry tank through a duct and the inlet is located below the inclined plate heat exchanger;

[0010] The vertical plate heat exchanger is set in the washing area and located between the liquid surface in the slurry tank and the flue gas inlet. It is connected in series with the inclined plate heat exchanger and includes several hollow heat exchange plates that are equally spaced and vertically installed. The hollow heat exchange plates have a heat exchange medium flow channel inside.

[0011] The heat exchange medium inlet of the inclined plate heat exchanger is connected to the low-temperature medium inlet pipe, and the heat exchange medium outlet is connected to the heat exchange medium inlet of the vertical plate heat exchanger through a pipeline. The heat exchange medium outlet of the vertical plate heat exchanger is connected to the high-temperature medium outlet pipe.

[0012] This application installs two layers of plate heat exchangers inside the desulfurization scrubbing tower. A vertical plate heat exchanger is installed below the flue gas inlet and above the liquid surface of the desulfurization slurry pool, while an inclined plate heat exchanger is installed below the liquid surface of the desulfurization slurry pool and above the outlet of the oxidation blower. The vertical plate heat exchanger and the inclined plate heat exchanger are connected in series. The internal circulating medium is raw water from the power plant's water treatment workshop or hot water supplied to the plant area. The vertical plate heat exchanger and the inclined plate heat exchanger cooperate with each other, and the circulating medium flows through the inclined plate heat exchanger and the vertical plate heat exchanger in sequence to efficiently recover the waste heat of gas and liquid in the scrubbing tower.

[0013] The vertical plate heat exchanger is positioned above the slurry surface in the slurry tank, exchanging heat with the high-temperature slurry after the washing and spraying process. The slurry continuously slides down and renews itself on the surface of the vertical plate heat exchanger before falling into the slurry tank after completing the heat exchange. The inclined plate heat exchanger is installed in the slurry tank, exchanging heat with the desulfurization slurry. Through two heat exchange processes, the waste heat from the gas and liquid phases is better recovered.

[0014] In addition to serving as a heat exchanger, the inclined plate heat exchanger also functions as a sedimentation and separation mechanism after in-situ oxidation of the desulfurization slurry within the tower. It works in conjunction with the in-situ oxidation of the desulfurization slurry within the tower. An oxidation fan blows air to oxidize the desulfurization slurry in situ within the slurry pool. During oxidation, the inclined plate heat exchanger stratifies the desulfurization slurry. The high-density gypsum slurry, after oxidation, gradually settles to the bottom of the slurry pool in the washing tower below the inclined plate heat exchanger. The low-density desulfurizing agent slurry and calcium sulfite are suspended above the inclined plate heat exchanger under the action of the oxidation air and are then pumped to the washing layer for spray washing. Both flue gas scrubbing and in-situ oxidation within the tower are continuous, ensuring efficient flue gas scrubbing and successful in-situ oxidation of the desulfurization slurry within the tower. The inclined plate heat exchanger design in this application not only solves the problem of efficient waste heat recovery but also addresses the balance between the efficiency of in-situ oxidation of the desulfurization slurry and the efficiency of spray washing.

[0015] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0016] Optionally, it also includes a washing pump and a washing sprayer, wherein the washing sprayer is disposed in the washing zone and located above the flue gas inlet, and the slurry inlet of the washing pump is connected to the slurry tank through a pipeline and the inlet is located above the inclined plate heat exchanger.

[0017] Optionally, the hollow heat exchange plate is a hollow metal plate, and adjacent hollow metal plates are connected sequentially through a medium flow pipe.

[0018] Optionally, the gap between adjacent hollow heat exchange plates is a slurry flow gap, and the ratio of the thickness of the hollow heat exchange plate to the width of the slurry flow gap is 1:1.5-1:3.

[0019] Optionally, the thickness of the hollow heat exchange plate is 5–20 mm. This thickness refers to the overall thickness of each hollow heat exchange plate.

[0020] Optionally, the hollow heat exchange plate of the inclined plate heat exchanger is tilted at an angle of 25-37° relative to the vertical plane.

[0021] Optionally, in the inclined plate heat exchanger, adjacent hollow heat exchange plates are parallel to each other; the projected height of the inclined plate heat exchanger on the vertical plane is 0.5 to 1.2 m.

[0022] Optionally, the inclined plate heat exchanger is located at 30-40% of the slurry level in the slurry tank. Preferably, it is located at one-third of the slurry level.

[0023] Optionally, the vertical plate heat exchanger is located at a height of at least 0.5m above the liquid surface in the slurry pool.

[0024] Optionally, the vertical plate heat exchanger has a height of 0.5 to 1.2 m in the vertical plane.

[0025] Optionally, a gypsum discharge pump is also included to discharge the oxidized gypsum slurry from the slurry tank outside the tower.

[0026] The proposed solution can be used to heat the raw water used for desalination in the water treatment workshop of a power plant, thereby reducing the energy consumption for boiler feedwater heating in the power plant. It can also be used to heat the domestic shower water in the power plant, thereby realizing the recovery and utilization of waste heat from the gas and liquid in the scrubbing tower.

[0027] Compared with existing technologies, it has at least one of the following beneficial effects:

[0028] (1) The inclined plate heat exchanger and the vertical plate heat exchanger work together to achieve high heat transfer efficiency and strong adaptability, and can efficiently recover the gas and liquid waste heat in the scrubbing tower.

[0029] (2) In addition to being a heat exchange device, the inclined plate heat exchanger also serves as a sedimentation and separation mechanism after in-situ oxidation of the desulfurization slurry in the tower. When combined with the in-situ oxidation of the desulfurization slurry in the tower, it can ensure the washing efficiency of the flue gas and also smoothly complete the in-situ oxidation of the desulfurization slurry in the tower. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the scrubbing tower in this application.

[0031] The reference numerals in the figure are as follows:

[0032] 1. Tower body; 2. Slurry tank; 3. Washing zone; 4. Drying zone; 5. Flue gas inlet; 6. Flue gas outlet; 7. Inclined plate heat exchanger; 8. Vertical plate heat exchanger; 9. Washing sprayer; 10. Oxidation fan; 11. Washing pump; 12. Gypsum discharge pump. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] like Figure 1 As shown, a scrubbing tower for recovering waste heat from gas and liquid includes a tower body 1, an inclined plate heat exchanger 7, a vertical plate heat exchanger 8, an oxidation fan 10, a scrubbing pump 11, and a gypsum discharge pump 12. This application installs two layers of plate heat exchangers inside the desulfurization scrubbing tower. The vertical plate heat exchanger 8 is installed between the slurry surface and the flue gas inlet, and the inclined plate heat exchanger 7 is installed below the slurry surface. The positions of the inclined plate heat exchanger 7 are coordinated with the inlets of the oxidation fan and the scrubbing pump.

[0036] Tower body 1 is the body of the spray scrubbing tower. At the bottom of the tower body is a slurry pool 2. Above the slurry pool are the washing zone 3 and the drying zone 4, respectively. The flue gas inlet 5 is located on the tower wall of the washing zone 3, and the flue gas outlet 6 is located at the top of tower body 1. Several layers of scrubbing sprayers 9 are installed within the washing zone 3 and above the flue gas inlet 5. A demister is installed in the drying zone 4. Both the scrubbing sprayers and the demister are conventional components within the scrubbing tower.

[0037] The inclined plate heat exchanger 7 is positioned below the liquid surface in the slurry tank 2. The inclined plate heat exchanger 7 comprises several equally spaced and inclined hollow heat exchange plates. The hollow heat exchange plates contain channels for the heat exchange medium, which can be used to circulate raw water from the power plant's water treatment workshop for desalination or domestic shower water. The oxidation air outlet of the oxidation blower 10 is connected to the slurry tank 2 via a duct, with this inlet located below the inclined plate heat exchanger 7. The slurry inlet of the washing pump 11 is connected to the slurry tank 2 via a pipeline, with this inlet located above the inclined plate heat exchanger 7. The slurry outlet of the washing pump 10 is connected to the spray scrubber 9 via a pipeline.

[0038] An inclined plate heat exchanger is installed in the slurry tank to exchange heat with the desulfurization slurry. The inclined plate heat exchanger is tilted, which facilitates the stratification of the oxidized desulfurization slurry while simultaneously recovering waste heat. An oxidation blower oxidizes the desulfurization slurry, and the inclined plate heat exchanger further stratifies it. The oxidized high-density gypsum slurry gradually settles to the bottom of the slurry tank in the washing tower below the inclined plate heat exchanger. The low-density desulfurizing agent slurry and calcium sulfite are suspended above the inclined plate heat exchanger under the action of the oxidation wind. While the desulfurization slurry continues to oxidize, it is also pumped to the washing layer for spray washing. In some embodiments, the inclination angle of the hollow heat exchange plate of the inclined plate heat exchanger 7 relative to the vertical plane is 25-37°. Furthermore, adjacent hollow heat exchange plates in the inclined plate heat exchanger 7 are arranged parallel to each other; the projected height of the inclined plate heat exchanger on the vertical plane is 0.5-1.2m.

[0039] The vertical plate heat exchanger 8 is located in the washing area 3, above the liquid surface in the slurry tank and below the flue gas inlet 5. The vertical plate heat exchanger 8 includes several equally spaced and vertically installed hollow heat exchange plates. The hollow heat exchange plates contain channels for the heat exchange medium, which can be used to circulate raw water from the power plant's water treatment workshop for desalination or domestic shower water. In some embodiments, the vertical plate heat exchanger is 0.5–1.2 m high in the vertical plane.

[0040] The adjacent hollow heat exchange plates of the inclined plate heat exchanger 7 are connected sequentially through a medium flow pipe, and the adjacent hollow heat exchange plates of the vertical plate heat exchanger 8 are also connected sequentially through a medium flow pipe. The inclined plate heat exchanger 7 has a heat exchange medium inlet and a heat exchange medium outlet, and the vertical plate heat exchanger 8 also has a heat exchange medium inlet and a heat exchange medium outlet. The inclined plate heat exchanger 7 and the vertical plate heat exchanger 8 are connected in series. The heat exchange medium inlet of the inclined plate heat exchanger 7 is connected to the low-temperature medium inlet pipe, the heat exchange medium outlet of the inclined plate heat exchanger 7 is connected to the heat exchange medium inlet of the vertical plate heat exchanger 8 through a pipe, and the heat exchange medium outlet of the vertical plate heat exchanger 8 is connected to the high-temperature medium outlet pipe.

[0041] The slurry inlet of the gypsum discharge pump 12 is connected to the slurry tank 2 through a pipeline. This connection point is located below the inclined plate heat exchanger 7. The high-density gypsum slurry that has completed oxidation gradually settles below the inclined plate heat exchanger 7 and is sent out of the tower body by the gypsum discharge pump 12.

[0042] As one embodiment of the hollow heat exchange plates in the vertical plate heat exchanger 8 and the inclined plate heat exchanger 7, the heat exchange plates can all be made of hollow metal plates, and the ratio of the thickness of the hollow metal plate to the width of the flow gap between the plates is 1:1.5-1:3. This setting ratio can maximize the heat exchange efficiency. In some embodiments, the thickness of the hollow metal plate (the overall thickness of the hollow metal plate) can be set to 5-20 mm.

[0043] In one embodiment of the relative positions of the inclined plate heat exchanger 7 and the vertical plate heat exchanger 8, the inclined plate heat exchanger 7 is located at one-third of the height of the slurry level, and the vertical plate heat exchanger 8 is located at least 0.5m above the liquid surface.

[0044] The working principle of this utility model is as follows:

[0045] Flue gas is fed into tower body 1 through flue gas inlet 5 and flows upward, contacting the washing slurry sprayed downward in the opposite direction. The washing slurry absorbs pollutants in the flue gas while reducing the flue gas temperature. The heat energy in the flue gas is transferred to the circulating slurry. After being washed and cooled, the flue gas is discharged from the flue gas outlet after being demisted and dried.

[0046] The heat exchange medium is fed in by the inclined plate heat exchanger 7 and flows through the inclined plate heat exchanger 7 and the vertical plate heat exchanger 8 in sequence.

[0047] During the process of the high-temperature slurry that has completed the washing spray falling, it first comes into contact with the vertical plate heat exchanger 8. The slurry continuously slides down and renews itself on the surface of the vertical plate heat exchanger 8, and falls into the slurry pool 2 after completing the heat exchange.

[0048] In the slurry tank 2, the desulfurized slurry exchanges heat with the inclined plate heat exchanger 7. At the same time, the oxidation blower 10 blows air into the slurry tank 2 to oxidize the desulfurized slurry. The inclined plate heat exchanger 7, while serving as a heat exchanger for the desulfurized slurry, also separates the oxidized desulfurized slurry into layers. The high-density gypsum slurry that has completed oxidation gradually settles below the inclined plate heat exchanger 7 and is discharged by the gypsum discharge pump 12. The low-density desulfurizing agent slurry and calcium sulfite are suspended above the inclined plate heat exchanger 7 under the action of the oxidation wind and are sent to the washing layer for spray washing by the washing pump 11. The flue gas washing and slurry oxidation are carried out simultaneously and continuously.

[0049] The heat extraction medium can be the raw water used for desalination in the water treatment workshop of a power plant or the domestic shower water of a power plant. The solution proposed in this application can be used to heat the raw water used for desalination in the water treatment workshop of a power plant, thereby reducing the energy consumption of boiler feed water heating in the power plant. It can also be used to heat the domestic shower water of the power plant, thereby realizing the recovery and utilization of waste heat from the gas and liquid in the scrubbing tower.

[0050] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A scrubbing tower for recovering waste heat from gas and liquid, characterized in that, include: The tower body has a slurry pool at the bottom, and above the slurry pool are the washing zone and the drying zone. The flue gas inlet is located on the tower wall of the washing zone, and the flue gas inlet is located at the top of the tower body. An inclined plate heat exchanger is installed in the slurry pool and located below the liquid surface. It includes several hollow heat exchange plates that are equally spaced and installed at an incline. The hollow heat exchange plates have channels for the flow of heat exchange medium. An oxidation blower, the oxidation air outlet of which is connected to the slurry tank through a duct and the inlet is located below the inclined plate heat exchanger; The vertical plate heat exchanger is set in the washing area and located between the liquid surface in the slurry tank and the flue gas inlet. It is connected in series with the inclined plate heat exchanger and includes several hollow heat exchange plates that are equally spaced and vertically installed. The hollow heat exchange plates have a heat exchange medium flow channel inside. The heat exchange medium inlet of the inclined plate heat exchanger is connected to the low-temperature medium inlet pipe, and the heat exchange medium outlet is connected to the heat exchange medium inlet of the vertical plate heat exchanger through a pipeline. The heat exchange medium outlet of the vertical plate heat exchanger is connected to the high-temperature medium outlet pipe.

2. The scrubbing tower according to claim 1, characterized in that, It also includes a washing pump and a washing sprayer. The washing sprayer is located in the washing area and above the flue gas inlet. The slurry inlet of the washing pump is connected to the slurry tank through a pipeline and the inlet is located above the inclined plate heat exchanger.

3. The scrubbing tower according to claim 1, characterized in that, The hollow heat exchange plate is a hollow metal plate, and adjacent hollow metal plates are connected in sequence through a medium flow pipe.

4. The scrubbing tower according to claim 1, characterized in that, The gap between adjacent hollow heat exchange plates is the slurry flow gap, and the ratio of the plate thickness of the hollow heat exchange plate to the width of the slurry flow gap is 1:1.5-1:

3.

5. The scrubbing tower according to claim 4, characterized in that, The thickness of the hollow heat exchange plate is 5~20mm.

6. The scrubbing tower according to claim 1, characterized in that, The hollow heat exchange plate of the inclined plate heat exchanger is tilted at an angle of 25-37° relative to the vertical plane.

7. The scrubbing tower according to claim 1, characterized in that, In the inclined plate heat exchanger, adjacent hollow heat exchange plates are parallel to each other; the projected height of the inclined plate heat exchanger on the vertical plane is 0.5-1.2m.

8. The scrubbing tower according to claim 1, characterized in that, The inclined plate heat exchanger is located at 30-40% of the slurry level in the slurry tank.

9. The scrubbing tower according to claim 1, characterized in that, The vertical plate heat exchanger is located at a height of at least 0.5m above the liquid surface in the slurry pool.

10. The scrubbing tower according to claim 1, characterized in that, The vertical plate heat exchanger has a vertical height of 0.5-1.2m.

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