CN212166984U - CO2 capture system - Google Patents

Abstract

The utility model proposes a _CO2 capture system, which comprises an absorption tower, a regeneration tower, a regeneration heat exchanger and a lean-rich liquid heat exchanger, and the rich liquid outlet of the absorption tower is connected with the cold source inlet of the regeneration heat exchanger , the cold source outlet of the regeneration heat exchanger is connected with the cold source inlet of the lean-rich liquid heat exchanger, the cold source outlet of the lean-rich liquid heat exchanger is connected with the rich liquid inlet of the regeneration tower; the regeneration mixed gas outlet of the regeneration tower It is connected with the heat source inlet of the regeneration heat exchanger; the lean liquid outlet of the regeneration tower is connected with the heat source inlet of the lean and rich liquid heat exchanger, and the heat source outlet of the lean and rich liquid heat exchanger is connected with the regeneration lean liquid inlet of the absorption tower. Compared with the prior art, the _CO2 capture system can efficiently recover the latent heat of the regeneration gas and the sensible heat of the regeneration lean liquid in the regeneration tower, effectively reduce the consumption of regeneration steam, and reduce the regeneration energy consumption of the system, and can be used in coal-fired power plants. , large-scale CO ₂ capture of flue gas in chemical plants and cement plants, with good application prospects.

Description

CO2 capture system

technical field

The utility model relates to the technical field of solvent absorption gas and solvent regeneration, in particular to a _CO2 capture system.

Background technique

Carbon dioxide capture and storage (CCS) technology is currently one of the most effective means to achieve large-scale carbon reduction. Among them, solvent-based CO ₂ capture technology has the advantages of good separation effect, mature and reliable technology, etc., but the current cost is relatively high for large-scale CO ₂ capture. Therefore, reducing energy consumption to reduce capture cost has become a research focus of solvent-based _CO capture technology.

The regeneration heat of the regeneration tower in the CO ₂ capture system is mainly distributed in two parts: one is the regeneration lean liquid of the regeneration tower tower bottom, and the other part is the regeneration mixed gas at the top of the regeneration tower tower. The traditional CO ₂ capture process simply recovers the heat of the regenerated lean liquid in the regenerator tower, which is used to heat the absorption rich liquid entering the regeneration tower, and does not consider the utilization of the latent heat of the regenerated mixed gas at the top of the regenerator tower, which will cause A lot of energy loss.

Utility model content

In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a _CO2 capture system, which can effectively utilize the latent heat of the regenerated mixed gas at the top of the regeneration tower and reduce the energy loss of the system.

A _CO2 capture system provided by the utility model has an absorption tower and a regeneration tower. The capture system further includes a regeneration heat exchanger and a lean-rich liquid heat exchanger. The rich liquid outlet at the bottom of the absorption tower is connected to the The cold source inlet of the regenerative heat exchanger is connected, the cold source outlet of the regenerative heat exchanger is connected with the cold source inlet of the lean-rich liquid heat exchanger, and the cold source outlet of the lean-rich liquid heat exchanger It is connected with the rich liquid inlet at the top of the regeneration tower; the regeneration mixed gas outlet at the top of the regeneration tower is connected with the heat source inlet of the regeneration heat exchanger; the lean liquid outlet at the bottom of the regeneration tower is connected with the The heat source inlet of the liquid heat exchanger is connected, and the heat source outlet of the lean-rich liquid heat exchanger is connected with the regeneration lean liquid inlet at the top of the absorption tower.

Preferably, it also includes a regenerative cooler and a gas-liquid separator, the inlet of the regenerative cooler is connected with the heat source outlet of the regenerative heat exchanger, and the outlet of the regenerative cooler is in phase with the inlet of the gas-liquid separator connect.

Preferably, the liquid phase outlet of the gas-liquid separator is connected to the regeneration condensate inlet of the regeneration tower.

Preferably, a pretreatment unit is also included, and the outlet of the pretreatment unit is connected to the flue gas inlet of the absorption tower.

Preferably, a circulating water washing device is also included, and the circulating water washing device is communicated with the top of the absorption tower.

Preferably, the circulating water washing device includes a water washing unit, a circulating water pump and a circulating water cooler, and the water washing unit, the circulating water pump and the circulating water cooler are sequentially connected through pipes to form a closed loop.

Compared with the prior art, the _CO2 capture system provided by the utility model can efficiently recover the latent heat of the regeneration gas and the sensible heat of the regeneration lean liquid in the regeneration tower. The system uses the latent heat of the regenerated mixed gas to preheat the absorption rich liquid, which can effectively recover all the effective heat of the regeneration gas. The temperature of the absorbed rich liquid entering the regeneration tower is further increased, which effectively reduces the consumption of regeneration steam and greatly reduces the regeneration energy consumption of the system. The utility model can be used for large-scale CO ₂ capture of flue gas in coal-fired power plants, chemical plants and cement plants, and has good application prospects.

The above technical features can be combined in various suitable ways or replaced by equivalent technical features, as long as the purpose of the present invention can be achieved.

Description of drawings

In the following the invention will be described in more detail on the basis of only non-limiting examples and with reference to the accompanying drawings. in:

Figure 1 is a schematic structural diagram of a _CO2 capture system provided by the present invention.

Description of reference numbers:

1, induced draft fan; 2, pretreatment unit; 3, absorption tower; 4, circulating water pump; 5, circulating water cooler; 6, rich liquid pump; 7, regeneration gas heat exchanger; 8, lean and rich liquid heat exchanger 9, regeneration tower; 10, reboiler; 11, tower kettle circulating pump; 12, regeneration cooler; 13, gas-liquid separator;

I, flue gas; II, regeneration of lean liquid; III, discharge of flue gas; IV, absorption of rich liquid; V, regeneration of mixed gas; VI, CO ₂ product gas; VII, regeneration of condensed water; VIII, additional circulating water.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely below. Based on the specific embodiments of the present invention, those of ordinary skill in the art will All other implementations obtained under the premise of labor belong to the scope of protection of the present invention.

The utility model proposes a _CO2 capture system, which can efficiently recover the latent heat of the regeneration gas and the sensible heat of the regeneration lean liquid II in the regeneration system. The system uses the latent heat of the regenerated mixed gas V to preheat the absorption rich liquid IV first, so that all the effective heat of the regeneration gas can be effectively recovered, and the preheated absorption rich liquid IV passes through the lean and rich liquid heat exchanger 8 for secondary Heating, so that the temperature of the absorption rich liquid IV entering the regeneration tower 9 is further increased, this system effectively reduces the consumption of regeneration steam and greatly reduces the regeneration energy consumption.

As shown in Figure 1, the _CO2 capture system provided in this embodiment mainly includes an induced draft fan 1, a pretreatment unit 2, an absorption tower 3, a regeneration heat exchanger, a lean-rich liquid heat exchanger 8, a regeneration tower 9, a regenerator Boiler 10, regeneration cooler 12 and gas-liquid separator 13. The outlet of the induced draft fan 1 is connected with the inlet of the pretreatment unit 2, and the outlet of the pretreatment unit 2 is connected with the flue gas inlet of the absorption tower 3; the rich liquid outlet at the bottom of the absorption tower 3 is connected with the cold source inlet of the regenerative heat exchanger Connected, a rich liquid pump 6 is arranged on the connecting pipeline of the two, and the absorption rich liquid IV discharged from the bottom of the absorption tower 3 is transported to the regeneration gas heat exchanger 7 through the rich liquid pump 6; The cold source inlet of the lean-rich liquid heat exchanger 8 is connected, and the cold source outlet of the lean-rich liquid heat exchanger 8 is connected with the rich liquid inlet at the top of the regeneration tower 9; the regeneration mixture V outlet at the top of the regeneration tower 9 is connected with the regeneration exchange The heat source inlet of the heat exchanger is connected; the heat source outlet of the regenerative heat exchanger is connected with the inlet of the regenerative cooler 12, the outlet of the regenerative cooler 12 is connected with the inlet of the vapor-liquid separator, and the liquid phase of the gas-liquid separator 13 is connected. The outlet is connected with the regenerated condensed water VII inlet at the top of the regeneration tower 9; the lean liquid outlet at the bottom of the regeneration tower 9 is connected with the heat source inlet of the lean-rich liquid heat exchanger 8, and a tower still circulating pump is provided on the connecting pipeline of the two 11. The regeneration lean liquid II discharged from the bottom of the regeneration tower 9 is transported to the lean and rich liquid heat exchanger 8 through the tower kettle circulating pump 11; the heat source outlet of the lean and rich liquid heat exchanger 8 and the regeneration lean liquid II inlet at the top of the absorption tower 3 connected. The reboiler 10 is used to heat the absorption rich liquid IV in the regeneration tower 9, so that the _CO2 in the absorption rich liquid IV is desorbed.

In order to further reduce the pollution of the exhausted flue gas III to the atmosphere, the capture system also includes a circulating water washing device. The circulating water washing device at least includes a water washing unit (not shown in the figure) and a circulating water pump 4. The circulating water washing device is connected to the top of the absorption tower 3. Pass. The decarbonized flue gas I in the absorption tower 3 enters the circulating water washing device, and is discharged into the atmosphere after removing the carried organic amine and part of the remaining gas impurities. Since the water temperature is too high, it will be unfavorable to remove organic amines and some remaining gas impurities in the flue gas I, so it is necessary to cool the circulating water in the circulating water washing device, so a circulating water cooler 5 can be added. The water pump 4 and the circulating water cooler 5 are sequentially connected through pipes to form a closed loop, so that the cooling and recycling of the circulating water can be realized. The water washing unit can be arranged in the absorption tower 3 or outside the absorption tower 3. In this embodiment, the water washing unit is arranged at the top of the absorption tower 3. The washing liquid obtained after the water washing passes through the circulating water pump 4, and then passes through the circulating water cooler 5. Entering the top of the regeneration tower 9 can maintain the water balance in the operation of the _CO2 capture method and device provided by the present invention, which is conducive to reducing water consumption and the long-term operation of the capture device, and can also stabilize the concentration of the absorbent in the absorption liquid for a long time. .

The process flow of _CO2 capture system to capture _CO2 is as follows:

The flue gas I is introduced into the pretreatment unit 2 through the induced draft fan 1 for pretreatment, which is used to remove sulfur dioxide and some gas impurities in the flue gas I. The pretreatment method includes: using a sodium hydroxide solution with a mass concentration of 5-10% or The circulating water is in contact with the flue gas I; wherein, the CO ₂ volume concentration in the flue gas I is 8%-13%, the concentration of sulfur dioxide in the flue gas I is more than 100ppm, and the concentration of sulfur dioxide in the flue gas I after pretreatment is 1ppm the following. The pretreated clean flue gas I enters the absorption tower 3 from the bottom, and the absorbent enters the countercurrent contact with the flue gas I from the top of the absorption tower 3, and the _CO2 in the flue gas I is trapped in the absorbent, and the absorption temperature is 20 -50℃, the absorption pressure is 1-1.3bar; the absorbent is ethanolamine MEA, methyldiethanolamine MDEA, piperazine PZ and sterically hindered amine AMP (2-amino-2-methyl-1-propanol). One or more, the concentration of the absorbent is 5%-50%, preferably the concentration is 20%-40%. The decarburized flue gas I continues to ascend into the circulating water washing device at the top of the absorption tower 3, and is discharged into the atmosphere after removing the carried organic amine and part of the remaining gas impurities. The absorption rich liquid IV from the bottom of the absorption tower 3 is preheated by the regeneration gas heat exchanger 7 first, and the preheated absorption rich liquid IV passes through the lean rich liquid heat exchanger 8 for secondary heating and then enters the regeneration tower 9. In the regeneration tower 9, the absorption rich liquid IV is heated by the reboiler 10, so that the _CO in the absorption rich liquid IV is desorbed. The regeneration temperature is 110-130 ° C, preferably the regeneration temperature is 115-125 ° C, and the regeneration pressure is 0.1-0.3 MPa, preferably the regeneration pressure is 0.15-0.25MPa. The regenerated absorbing lean liquid is discharged from the bottom of the regeneration tower 9 and then exchanges heat with the absorbing rich liquid IV, and then returns to the top of the absorption tower 3 for recycling. In the regeneration tower 9, part of the water is vaporized and desorbed from the CO ₂ product gas VI mixed into a regeneration gas mixture V, after the regeneration gas mixture V is discharged from the top of the regeneration tower 9, it passes through the regeneration gas heat exchanger 7 and absorbs the rich liquid. After the heat exchange, IV enters the gas-liquid separator 13 after being cooled by the regeneration cooler 12, and _CO is separated from the top of the gas-liquid separator 13 to obtain the product gas VI; the regeneration condensed water VII is separated from the bottom of the gas-liquid separator 13. After coming out, it returns to the regeneration tower 9 to maintain the water balance of the system.

The CO ₂ capture system provided by the present application will be further described below with reference to the examples.

Example 1

The absorbent adopts 30% ethanolamine MEA, and the specific implementation steps are as follows:

1) The flue gas 1 enters the pretreatment unit 2 through the induced draft fan 1 from the outlet of the flue gas desulfurization (FGD) for pretreatment to remove sulfur dioxide and some gas impurities, and the SO concentration in the flue gas ₁ will be below 1ppm;

2) The clean flue gas I from the pretreatment device enters the absorption tower 3 from the bottom, and the 30% ethanolamine MEA solution enters from the top of the absorption tower 3 into countercurrent contact with the flue gas I, and the CO ₂ in the flue gas I is trapped in the solvent ;

3) the flue gas 1 after the decarbonization continues to ascend and enter the circulating water washing device at the top of the absorption tower 3, and is discharged into the atmosphere after removing the organic amine carried and part of the remaining gas impurities;

4) After the absorption rich liquid IV that comes out from the bottom of the absorption tower 3 is transported to the regeneration gas heat exchanger 7 by the rich liquid pump 6 for preheating, and then enters the top of the regeneration tower 9 after being reheated by the lean and rich liquid heat exchanger 8 Regenerate. In the regeneration tower 9, the _CO in the absorption rich liquid IV is desorbed by heating by the reboiler 10; The temperature after secondary heating by the lean-rich liquid heat exchanger 8 is 116°C, the regeneration temperature of the regeneration tower 9 is 125°C, and the regeneration pressure is 0.2MPa;

5) in the regeneration tower 9, part of the water is vaporized and with the desorbed CO ₂ from the regeneration tower 9 tower top enters the regeneration gas heat exchanger 7 after heat exchange, then enters the gas-liquid separator 13 via the regeneration cooler 12, CO ₂ is separated from the top of the separator to obtain product gas VI; regeneration condensed water VII is returned to regeneration tower 9 to maintain system water balance.

6) After the regeneration lean liquid II comes out from the bottom of the regeneration tower 9, it exchanges heat with the absorption rich liquid IV in the lean and rich liquid heat exchanger 8 through the tower kettle circulating pump 11, and then returns to the top of the absorption tower 3 for recycling.

In this embodiment, the CO ₂ capture rate of the flue gas I is 90%, and the capture energy consumption is 3.3 GJ/tCO ₂ , which can reduce the regeneration energy consumption by 21% compared to the traditional process.

Example 2

The absorbent adopts 30% ethanolamine MEA, and the specific implementation steps are as follows:

1) The flue gas I enters the pretreatment device through the induced draft fan 1 from the outlet of the flue gas desulfurization (FGD) for pretreatment to remove sulfur _dioxide and some gas impurities, and the SO2 concentration in the flue gas I will be below 1ppm;

2) The clean flue gas I from the pretreatment device enters the absorption tower 3 from the bottom, and the 30% ethanolamine MEA solution enters from the top of the absorption tower 3 into countercurrent contact with the flue gas I, and the CO ₂ in the flue gas I is trapped in the solvent ;

3) the flue gas 1 after the decarbonization continues to ascend and enter the circulating water washing device at the top of the absorption tower 3, and is discharged into the atmosphere after removing the organic amine carried and part of the remaining gas impurities;

4) After the absorption rich liquid IV that comes out from the bottom of the absorption tower 3 is transported to the regeneration gas heat exchanger 7 by the rich liquid pump 6 for preheating, and then enters the top of the regeneration tower 9 after being reheated by the lean and rich liquid heat exchanger 8 Regenerate. In the regeneration tower 9, the _CO in the absorption rich liquid IV is desorbed by heating by the reboiler 10;

In this step, the temperature of the absorption rich liquid IV after being preheated by the regenerating gas heat exchanger 7 is 89 °C, and the temperature of the absorption rich liquid IV after the secondary heating of the lean rich liquid heat exchanger 8 is 108 °C, and the temperature of the regeneration tower 9 is 108 °C. The regeneration temperature is 115 ℃, and the regeneration pressure is 0.15MPa;

5) in the regeneration tower 9, part of the water is vaporized and with the desorbed CO ₂ from the regeneration tower 9 tower top enters the regeneration gas heat exchanger 7 after heat exchange, then enters the gas-liquid separator 13 via the regeneration cooler 12, CO ₂ is separated from the top of the separator to obtain product gas VI; regeneration condensed water VII is returned to regeneration tower 9 to maintain system water balance.

6) After the regeneration lean liquid II comes out from the bottom of the regeneration tower 9, it exchanges heat with the absorption rich liquid IV in the lean and rich liquid heat exchanger 8 through the tower kettle circulating pump 11, and then returns to the top of the absorption tower 3 for recycling.

In this embodiment, the CO ₂ capture rate of the flue gas I is 90%, and the capture energy consumption is 3.8 GJ/tCO ₂ , which can reduce the regeneration energy consumption by 10% compared with the traditional process.

Finally, it should be noted that: the above embodiments and examples are only used to illustrate the technical solutions of the present utility model, but not to limit it; although the present utility model has been described in detail with reference to the foregoing The skilled person should understand that it is still possible to modify the technical solutions described in the foregoing embodiments or examples, or perform equivalent replacements to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the present utility. The spirit and scope of the new embodiments or example technical solutions.

Claims (6)

1. a _CO2 capture system, with absorption tower and regeneration tower, it is characterized in that, described capture system also comprises regeneration heat exchanger and lean and rich liquid heat exchanger, the rich liquid outlet at the bottom of described absorption tower and The cold source inlet of the regenerative heat exchanger is connected, the cold source outlet of the regenerative heat exchanger is connected with the cold source inlet of the lean-rich liquid heat exchanger, and the cold source of the lean-rich liquid heat exchanger is connected. The outlet is connected with the rich liquid inlet at the top of the regeneration tower; the regeneration mixed gas outlet at the top of the regeneration tower is connected with the heat source inlet of the regeneration heat exchanger; the lean liquid outlet at the bottom of the regeneration tower is connected with the lean liquid outlet The heat source inlet of the rich liquid heat exchanger is connected, and the heat source outlet of the lean rich liquid heat exchanger is connected with the regeneration lean liquid inlet at the top of the absorption tower. 2. The _CO2 capture system according to claim 1, characterized in that it further comprises a regeneration cooler and a gas-liquid separator, the inlet of the regeneration cooler is connected with the heat source outlet of the regeneration heat exchanger, and the The outlet of the regeneration cooler is connected with the inlet of the gas-liquid separator. 3 . The CO ₂ capture system according to claim 2 , wherein the liquid phase outlet of the gas-liquid separator is connected to the regeneration condensed water inlet of the regeneration tower. 4 . 4 . The CO ₂ capture system according to claim 1 , further comprising a pretreatment unit, the outlet of the pretreatment unit is connected with the flue gas inlet of the absorption tower. 5 . 5 . The CO ₂ capture system according to claim 1 , further comprising a circulating water washing device, and the circulating water washing device is communicated with the top of the absorption tower. 6 . 6. The _CO2 capture system according to claim 5, wherein the circulating water washing device comprises a water washing unit, a circulating water pump and a circulating water cooler, the water washing unit, the circulating water pump and the circulating water The coolers are connected in sequence through pipes to form a closed circuit.

Images