Multi-stage cross-flow absorption tower and multi-stage cross-flow absorption method using the same

Abstract

The invention discloses a multi-stage cross-flow absorption tower and a multi-stage cross-flow absorption method using the same. The multi-stage cross-flow absorption tower comprises: a tower body, the two ends of which are respectively connected to a flue gas inlet and a flue gas outlet; a plurality of filler absorption sections, which are arranged transversely in the tower body; a demister, which is arranged in the tower body; a plurality of spray pipes and liquid accumulation tanks, the spray pipes are arranged above each filler absorption section, and the liquid accumulation tanks are arranged below each filler absorption section; a heat exchanger, wherein a circulating solution circulates between the spray pipes, the filler absorption section, the liquid accumulation tank and the heat exchanger; a cold source inlet and a cold source outlet, wherein a cold source medium enters from the cold source inlet, flows into the heat exchanger for heat exchange, and flows to the cold source outlet. The invention not only improves the absorption efficiency and the thermal energy efficiency ratio, but also reduces the height in the longitudinal direction due to the transverse arrangement, thereby overcoming the floating liquid problem of the traditional countercurrent tower body. At the same time, it can also save equipment investment costs and optimize site layout.

Description

Technical Field

[0001] The invention relates to a multi-stage cross-flow absorption tower and a multi-stage cross-flow absorption method using the same. Background Art

[0002] At present, in the fields of boiler flue gas desulfurization, denitrification, and denitrification, conventional absorption towers generally adopt a single-stage countercurrent tower vertical tower structure, and do not use cross-flow towers. Cross-flow towers are mainly used in cold crossing towers.

[0003] Compared with the cross-flow tower, the total height of the counter-flow vertical tower is significantly larger, and the wind speed is higher, so the floating liquid volume is also larger. The vertical tower generally adopts single-stage absorption, which has low efficiency and low overall COP (thermal efficiency ratio). The vertical tower adopts multi-stage counter-flow absorption, which requires the design of an air lift device. The air lift device itself has a greater risk of leakage, so it is not easy to adopt. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art that the vertical tower structure of the absorption tower using multi-stage absorption is prone to leakage, and the single-stage absorption has low absorption efficiency and low thermal energy efficiency, and to provide a multi-stage cross-flow absorption tower and a multi-stage cross-flow absorption method using the same.

[0005] The present invention solves the above technical problems through the following technical solutions:

[0006] A multi-stage cross-flow absorption tower, characterized in that the multi-stage cross-flow absorption tower comprises:

[0007] a tower body, wherein two ends of the tower body are respectively connected to a smoke inlet and a smoke outlet;

[0008] A plurality of filler absorption sections, wherein the filler absorption sections are arranged transversely in the tower body;

[0009] A demister, wherein the demister is disposed in the tower body;

[0010] A plurality of spray pipes and liquid collection tanks, wherein the spray pipes are arranged above each of the filler absorption sections, and the liquid collection tanks are arranged below each of the filler absorption sections;

[0011] A heat exchanger, wherein a circulating solution circulates between the spray pipe, the filler absorption section, the liquid accumulation tank and the heat exchanger;

[0012] A cold source inlet and a cold source outlet, a cold source medium enters from the cold source inlet, flows into the heat exchanger for heat exchange, and flows to the cold source outlet.

[0013] In this solution, the heat of the circulating fluid is transferred to the cold source medium through the heat exchanger. The circulating fluid temperature is reduced, and it contacts the incoming flue gas through the spray pipe in a cross-flow spray, continuing to absorb the flue gas heat and water vapor. Ultimately, the flue gas dry bulb and dew point temperature are reduced, the cold source temperature is increased, and the flue gas waste heat recovery is achieved.

[0014] This solution effectively combines multi-stage solution spraying with a cross-flow tower, which not only improves the absorption efficiency and thermal energy efficiency, but also reduces the height in the vertical direction due to the horizontal setting, overcoming the problem of liquid floating in the traditional counter-current tower. At the same time, it can also save equipment investment costs and optimize site layout.

[0015] Preferably, the multi-stage cross-flow absorption tower further comprises a self-circulating solution pump, and the circulating solution circulates through the self-circulating solution pump.

[0016] Preferably, the number of the packing absorption sections and heat exchangers is 3, including a first-stage packing absorption section and a corresponding first-stage heat exchanger; a second-stage packing absorption section and a corresponding second-stage heat exchanger; and a third-stage packing absorption section and a corresponding third-stage heat exchanger.

[0017] Preferably, the circulating solution is water or a water-absorbing solution, such as a CaCl2 solution, LiBr, ethylene glycol, etc.

[0018] Preferably, the cold source medium is process cooling water, desalted water or boiler heating return water.

[0019] Preferably, the circulating solutions corresponding to the primary packing absorption section, the secondary packing absorption section and the tertiary packing absorption section are CaCl2 with concentrations of 15%, 12% and 10% respectively, and the circulation volume of the circulating solutions is 500t / h.

[0020] Among them, the flue gas temperature gradually decreases along the flue gas flow direction. There is a gradient difference in the temperature and concentration of the circulating liquid of the three-stage spraying along the flue gas flow direction. The temperature gradually decreases along the flue gas flow direction. The temperature of the cold source medium increases successively after the three-stage self-circulation heat exchange, the two-stage self-circulation heat exchange, and the one-stage self-circulation heat exchange.

[0021] Preferably, process cooling water with a flow rate of 570 t / h flows through the primary heat exchanger, the secondary heat exchanger and the tertiary heat exchanger.

[0022] Preferably, the tower body further comprises a liquid storage tank, which is connected to the bottom of the tower body through an overflow conduit. The liquid entrained at the end can be recovered through the liquid storage tank to reduce the entrainment of droplets at the flue gas outlet.

[0023] Preferably, the demister is arranged after the packing absorption section.

[0024] Preferably, the tower body is connected to the smoke inlet from the side, and the tower body is connected to the smoke outlet upward.

[0025] Preferably, the circulating solution is sprayed out from the spray pipe and contacts with the incoming flue gas in a transverse cross-flow manner.

[0026] Preferably, the cold source medium is connected in series with the heat exchangers, wherein the cold source medium enters from the cold source inlet, flows into each of the heat exchangers in sequence for heat exchange, and flows to the cold source outlet.

[0027] Preferably, the cold source medium is connected in parallel with the heat exchangers, wherein the cold source medium enters each of the heat exchangers from the cold source inlet and flows from each of the heat exchangers to the cold source outlet.

[0028] A multi-stage cross-flow absorption method is characterized in that it is implemented by using the multi-stage cross-flow absorption tower, comprising:

[0029] Step S1, flue gas enters the tower body from the flue gas inlet;

[0030] Step S2, the flue gas contacts the circulating solution in each filler absorption section;

[0031] Step S3, the flue gas flows to the demister;

[0032] Step S4: The smoke flows out from the smoke outlet.

[0033] Preferably, in step S2, the circulating solution is sprayed out from the spray pipe and is contained in the liquid storage tank after being in cross-flow contact with the incoming flue gas. Subsequently, the circulating solution enters the heat exchanger from the liquid storage tank to exchange heat with the cold source medium.

[0034] The positive effect of the present invention is that the present invention effectively combines multi-stage solution spraying with a cross-flow tower, which not only improves the absorption efficiency and thermal energy efficiency ratio, but also reduces the height in the vertical direction due to the horizontal arrangement, thus overcoming the problem of liquid floating in the traditional counter-flow tower. At the same time, it can also save equipment investment costs and optimize site layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the structure of a multi-stage cross-flow absorption tower according to Example 1 of the present invention.

[0036] Figure 2 This is a schematic diagram of the structure of a multi-stage cross-flow absorption tower according to Example 2 of the present invention.

[0037] Figure 3 Flow chart of the multi-stage cross-flow absorption method of Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment discloses a multi-stage cross-flow absorption tower, which includes:

[0041] A tower body 1, two ends of which are respectively connected to a smoke inlet 21 and a smoke outlet 22;

[0042] A plurality of filler absorption sections 11, the filler absorption sections 11 are arranged transversely in the tower body 1;

[0043] A demister 12, wherein the demister 12 is disposed in the tower body 1;

[0044] A plurality of spray pipes 61 and liquid collection tanks 62, wherein the spray pipes 61 are arranged above each filler absorption section 11, and the liquid collection tanks 62 are arranged below each filler absorption section 11;

[0045] Heat exchanger 5, the circulating solution circulates between the spray pipe 61, the filler absorption section 11, the liquid accumulation tank 62 and the heat exchanger 5;

[0046] A cold source inlet 31 and a cold source outlet 32 ​​, the cold source medium enters from the cold source inlet 31 , flows into the heat exchanger 5 for heat exchange, and flows to the cold source outlet 32 ​​.

[0047] In this solution, the heat of the circulating fluid is transferred to the cold source medium through the heat exchanger 5. The circulating fluid temperature is reduced, and it contacts the incoming flue gas through the spray pipe 61 in a cross-flow spray, and continues to absorb the flue gas heat and water vapor. Finally, the flue gas dry bulb and dew point temperature are reduced, the cold source temperature is increased, and the flue gas waste heat recovery is realized.

[0048] This solution effectively combines multi-stage solution spraying with a cross-flow tower, which not only improves the absorption efficiency and thermal energy efficiency ratio, but also reduces the height in the vertical direction due to the horizontal setting, overcoming the problem of liquid floating in the traditional counter-current tower body 1. At the same time, it can also save equipment investment costs and optimize site layout.

[0049] like Figure 1 As shown, the multi-stage cross-flow absorption tower also includes a self-circulating solution pump 4, and the circulating solution circulates through the self-circulating solution pump 4.

[0050] In this embodiment, the number of the packing absorption sections 11 and the number of the heat exchangers 5 are both 3. From the figure, along the flue gas entry direction, they include a first-stage packing absorption section and a corresponding first-stage heat exchanger (the packing absorption section 11 and the heat exchanger 5 on the far left in the figure); a second-stage packing absorption section and a corresponding second-stage heat exchanger (the packing absorption section 11 and the heat exchanger 5 in the middle of the figure); and a third-stage packing absorption section and a corresponding third-stage heat exchanger (the packing absorption section 11 and the heat exchanger 5 on the far right in the figure).

[0051] In this embodiment, the circulating solution is water or a water-absorbing solution, such as a CaCl2 solution, LiBr, ethylene glycol, etc.

[0052] In further implementation, the circulating solutions corresponding to the primary packing absorption section, the secondary packing absorption section and the tertiary packing absorption section are CaCl2 with concentrations of 15%, 12% and 10% respectively, and the circulation volume of the circulating solutions is 500t / h.

[0053] Among them, the flue gas temperature gradually decreases along the flue gas flow direction. There is a gradient difference in the temperature and concentration of the circulating liquid of the three-stage spraying along the flue gas flow direction. The temperature gradually decreases along the flue gas flow direction. The temperature of the cold source medium increases successively after the three-stage self-circulation heat exchange, the two-stage self-circulation heat exchange, and the one-stage self-circulation heat exchange.

[0054] In this embodiment, the cold source medium may be process cooling water, demineralized water or boiler heating return water.

[0055] In a specific implementation, the first-stage heat exchanger, the second-stage heat exchanger and the third-stage heat exchanger of this embodiment all flow with process cooling water with a flow rate of 570 t / h.

[0056] The tower body 1 of this embodiment further comprises a liquid storage tank 7, which is connected to the bottom of the tower body 1 through an overflow conduit. The liquid entrained at the end can be recovered through the liquid storage tank 7, thereby reducing the entrainment of droplets at the smoke outlet 22.

[0057] like Figure 1 As shown, the demister 12 is arranged after the packing absorption section 11. The tower body 1 is connected to a flue gas inlet 21 from the side, and the tower body 1 is connected to a flue gas outlet 22 upward.

[0058] The circulating solution of this embodiment is sprayed out from the spray pipe 61 and contacts with the incoming flue gas in a transverse cross-flow manner.

[0059] like Figure 1 As shown, the cold source medium of this embodiment is connected in series with the heat exchanger 5 , wherein the cold source medium enters from the cold source inlet 31 , flows into each heat exchanger 5 in sequence along the direction of the arrow for heat exchange, and flows to the cold source outlet 32 ​​.

[0060] like Figure 2As shown, this embodiment also discloses a multi-stage cross-flow absorption method, which is implemented by a multi-stage cross-flow absorption tower, including:

[0061] Step S1, flue gas enters the tower body 1 from the flue gas inlet 21;

[0062] Step S2, the flue gas contacts the circulating solution in each filler absorption section 11;

[0063] Step S3, the flue gas flows to the demister 12;

[0064] Step S4 : The smoke flows out from the smoke outlet 22 .

[0065] In step S2, the circulating solution is sprayed out from the spray pipe 61, and is contained in the liquid storage tank 62 after being in cross-flow contact with the incoming flue gas. Then, the circulating solution enters the heat exchanger 5 from the liquid storage tank 62 to exchange heat with the cold source medium.

[0066] In the specific application process, for example, the 50℃ wet flue gas from the original desulfurization tower is 25000Nm 3 / h, enters the tower body 1 from the bottom side of the multi-stage cross-flow tower and first contacts with the first-stage self-circulating spray liquid in cross-flow. After the cross-flow spray of the circulating solution, the dew point of the flue gas is reduced to 47°C.

[0067] At this time, in the tower body 1, the spray liquid temperature rises from 41.1°C to 46°C, and the solution in the bottom liquid storage tank 62 of the leftmost filler absorption section 11 (first-stage filler absorption section) exchanges heat with the cooling process water preheated by the middle heat exchanger 5 (second-stage heat exchanger) and the temperature drops from 46°C to 41.1°C, and enters the middle filler absorption section 11 (second-stage filler absorption section) for spraying to further absorb flue gas heat and moisture. In the leftmost heat exchanger 5 (first-stage heat exchanger), the cooling process water rises from 35.8°C to 40°C.

[0068] After the primary solution spraying and absorption, the flue gas enters the middle packing absorption section 11 (secondary packing absorption section). After the secondary circulating solution in the tower body 1 absorbs the heat of the flue gas, the temperature rises from 39.1°C to 42°C. In the middle heat exchanger 5 (secondary heat exchanger), the cooling process water temperature rises from 33.3°C to 35.8°C. After the secondary spraying, the flue gas temperature drops from 47°C to 45°C.

[0069] After being sprayed and absorbed by the secondary solution, the flue gas enters the rightmost packed absorption section 11 (tertiary packed absorption section). After the tertiary circulating solution in the cross-flow tower absorbs the heat of the flue gas, the temperature rises from 35.8°C to 39.6°C. In the rightmost heat exchanger 5 (tertiary heat exchanger), the cooling process water temperature rises from 30°C to 33.3°C.

[0070] Finally, the remaining circulating liquid that absorbs the flue gas condensate enters the liquid storage tank through the overflow pipe with a flow rate of 3Nm3 / h. After three-stage spraying, the flue gas temperature drops from 45℃ to 42℃.

[0071] Among them: the circulation volume of the first, second and third stage solutions is 500t / h, and the circulating solution is 15%, 12%, and 10% CaCl2 solution. The first, second and third stage cooling process water is 570t / h. Finally, the flue gas waste heat recovery is 7MW. Whitening is achieved at an external temperature of 0℃.

[0072] This embodiment effectively combines multi-stage solution spraying with a cross-flow tower, which not only improves the absorption efficiency and thermal energy efficiency ratio, but also reduces the height in the vertical direction due to the horizontal setting, overcoming the problem of liquid floating in the traditional counter-flow tower. At the same time, it can also save equipment investment costs and optimize site layout.

[0073] Example 2

[0074] like Figure 2 As shown, the difference between this embodiment and embodiment 1 is that the cold source medium of this embodiment is connected in parallel with the heat exchanger 5, wherein the cold source medium enters each heat exchanger 5 from the cold source inlet 31 respectively, and flows from each heat exchanger 5 to the cold source outlet 32 ​​respectively.

[0075] The other configurations of this embodiment are the same as those of Embodiment 1, and thus will not be described in detail here.

[0076] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A multi-stage cross-flow absorption tower, characterized in that: The multi-stage cross-flow absorption tower comprises: a tower body, wherein two ends of the tower body are respectively connected to a smoke inlet and a smoke outlet; A plurality of filler absorption sections, wherein the filler absorption sections are arranged transversely in the tower body; A demister, wherein the demister is disposed in the tower body; A plurality of spray pipes and liquid collection tanks, wherein the spray pipes are arranged above each of the filler absorption sections, and the liquid collection tanks are arranged below each of the filler absorption sections; Heat exchanger, the circulating solution circulates between the spray pipe, the filler absorption section, the liquid accumulation tank and the heat exchanger, the number of the filler absorption sections and the heat exchanger are both 3, which include a primary filler absorption section and a corresponding primary heat exchanger; a secondary filler absorption section and a corresponding secondary heat exchanger; a tertiary filler absorption section and a corresponding tertiary heat exchanger, the circulating solutions corresponding to the primary filler absorption section, the secondary filler absorption section and the tertiary filler absorption section are CaCl2 with concentrations of 15%, 12% and 10% respectively, and the circulation volume of the circulating solution is 500t / h, the primary heat exchanger, the secondary heat exchanger and the tertiary heat exchanger are all circulated with process cooling water with a flow rate of 570t / h, and the cold source medium is connected in series with the heat exchanger; A cold source inlet and a cold source outlet, the cold source medium enters from the cold source inlet, flows into the heat exchanger in turn for heat exchange, and flows to the cold source outlet, the multi-stage cross-flow absorption tower also includes a self-circulating solution pump, and the circulating solution circulates through the self-circulating solution pump.

2. The multi-stage cross-flow absorption tower according to claim 1, characterized in that: The cold source medium is process cooling water, desalted water or boiler heating return water.

3. The multi-stage cross-flow absorption tower according to claim 1, characterized in that: The tower body also includes a liquid storage tank, which is connected to the bottom of the tower body through an overflow conduit.

4. The multi-stage cross-flow absorption tower according to claim 1, characterized in that: The demister is arranged after the packing absorption section.

5. The multi-stage cross-flow absorption tower according to claim 1, characterized in that: The tower body is connected to the smoke inlet from the side, and is connected to the smoke outlet upward.

6. The multi-stage cross-flow absorption tower according to claim 1, characterized in that: The circulating solution is sprayed out from the spray pipe and contacts with the incoming flue gas in a transverse cross-flow manner.

7. A multi-stage cross-flow absorption method, characterized in that: It is implemented by using a multi-stage cross-flow absorption tower as described in any one of claims 1 to 6, comprising: Step S1, flue gas enters the tower body from the flue gas inlet; Step S2, the flue gas contacts the circulating solution in each filler absorption section; Step S3, the flue gas flows to the demister; Step S4: The smoke flows out from the smoke outlet.

8. The multi-stage cross-flow absorption method according to claim 7, characterized in that: In step S2, the circulating solution is sprayed out from the spray pipe, and is contained in the liquid storage tank after being in cross-flow contact with the incoming flue gas. Then, the circulating solution enters the heat exchanger from the liquid storage tank to exchange heat with the cold source medium.

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