阅读说明：本技术 用于烟气低温污染物脱除的载冷剂脱水系统及脱水方法 (Secondary refrigerant dehydration system and dehydration method for removing low-temperature pollutants in flue gas ) 是由 万启超 于 2021-08-24 设计创作，主要内容包括：本发明公开了用于烟气低温污染物脱除的载冷剂脱水系统及脱水方法,该系统包括依次与烟气冷却塔上设置的载冷剂循环液出口相连接的载冷剂缓冲罐、三级循环泵和三级循环冷却器,三级循环冷却器出口与载冷剂循环液入口相连,烟气冷却塔的烟气出口连接有吸附器,吸附器通过烟气管道与载冷剂除水塔的烟气入口相连,三级循环泵的出口分为两路,其中一路连接到三级循环冷却器的循环液入口,另外一路连接到所述载冷剂除水塔的循环液入口,本发明将脱硫和氮的干烟气与载冷剂逆流接触,用干烟气带走载冷剂中的水分,可对载冷剂中的水分进行有效连续性脱除,不增加系统能耗,装置简单易实现。(The invention discloses a secondary refrigerant dehydration system and a dehydration method for removing low-temperature pollutants in flue gas, the system comprises a secondary refrigerant buffer tank, a three-stage circulating pump and a three-stage circulating cooler which are sequentially connected with a secondary refrigerant circulating liquid outlet arranged on a flue gas cooling tower, the outlet of the three-stage circulating cooler is connected with a secondary refrigerant circulating liquid inlet, the flue gas outlet of the flue gas cooling tower is connected with an absorber, the absorber is connected with the flue gas inlet of a secondary refrigerant water removal tower through a flue gas pipeline, the outlet of the three-stage circulating pump is divided into two paths, one path is connected to the circulating liquid inlet of the three-stage circulating cooler, the other path is connected to the circulating liquid inlet of the secondary refrigerant water removal tower, the invention carries out countercurrent contact between desulfurized and nitrogen dry flue gas and the secondary refrigerant, takes away the moisture in the secondary refrigerant with the dry flue gas, can carry out effective continuous removal on the moisture in the secondary refrigerant, and does not increase the energy consumption of the system, the device is simple and easy to realize.)

1. A secondary refrigerant dewatering system for desorption of flue gas low temperature pollutant, including flue gas cooling tower (1), have set gradually one-level cooling spray set, second grade cooling spray set and tertiary cooling spray set, its characterized in that along flue gas air current direction in flue gas cooling tower (1): the flue gas outlet of the flue gas cooling tower (1) is connected with an adsorber (12), the adsorber (12) is used for removing sulfur and nitrate components in flue gas, the outlet of the adsorber (12) is connected with the flue gas inlet of a secondary refrigerant water removal tower (13) through a flue gas pipeline, the circulating liquid outlet of a three-stage cooling spray device is connected with the inlet of a three-stage circulating pump (4) through a pipeline via a secondary refrigerant buffer tank (11), the outlet of the three-stage circulating pump (4) is divided into two paths, one path of the outlet is connected to the circulating liquid inlet of a three-stage circulating cooler (9), the other path of the outlet is connected to the circulating liquid inlet of the secondary refrigerant water removal tower (13), the circulating liquid inlet of the three-stage cooling spray device is communicated with the circulating liquid outlet of the three-stage circulating cooler (9), and the circulating liquid outlet of the secondary refrigerant water removal tower (13) is connected to the secondary refrigerant buffer tank (11), and the circulating liquid used by the three-stage cooling spraying device is a secondary refrigerant.

2. The coolant dewatering system for low-temperature flue gas pollutant removal according to claim 1, characterized in that: and a cold quantity recoverer (6) is arranged on the flue gas pipeline, and the cold quantity recoverer (6) is used for recovering cold quantity in the flue gas.

3. The coolant dewatering system for low-temperature flue gas pollutant removal according to claim 2, characterized in that: the circulating liquid outlet of the primary cooling spray device is connected with the primary circulating pump (2) through a pipeline, the outlet of the primary circulating pump (2) is connected with the circulating liquid inlet of the primary circulating cooler (5), the outlet of the primary circulating cooler (5) is connected with the circulating liquid inlet of the cold energy recoverer (6), the circulating liquid outlet of the cold energy recoverer (6) is connected with the circulating liquid inlet of the primary cooling spray device, and circulating liquid used by the primary cooling spray device is cooling water.

4. The secondary refrigerant dehydration system for low temperature pollutant removal of flue gas according to claim 3, characterized in that: and a cooling water inlet of the primary circulating cooler (5) is connected with a circulating cooling water feeding pipeline of the power plant, and a cooling water outlet of the primary circulating cooler (5) is connected with a circulating cooling water return pipeline of the power plant.

5. The coolant dewatering system for low-temperature flue gas pollutant removal according to claim 1, characterized in that: and a circulating liquid outlet of the second-stage cooling spraying device is connected with a second-stage circulating pump (3) through a pipeline, an outlet of the second-stage circulating pump (3) is connected with an inlet of a second-stage circulating cooler (7), an outlet of the second-stage circulating cooler (7) is connected with a circulating liquid inlet of the second-stage cooling spraying device, and circulating liquid used by the second-stage cooling spraying device is cooling water.

6. The coolant dewatering system for low-temperature flue gas pollutant removal according to claim 5, characterized in that: a cooling water inlet and outlet of the secondary circulating cooler (7) are connected with an inlet and outlet of a first refrigerating machine (8); the cooling water inlet and outlet of the three-stage circulating cooler (9) are connected with the inlet and outlet of the second refrigerating machine (10).

7. The coolant dewatering system for low-temperature flue gas pollutant removal according to claim 1, characterized in that: the secondary refrigerant is salt secondary refrigerant.

8. The coolant dewatering system for low-temperature flue gas pollutant removal according to claim 1, characterized in that: and a bypass pipeline connected with a chimney is arranged on the flue gas pipeline, and a flue gas outlet of the secondary refrigerant water removal tower (13) is connected with the chimney.

9. The coolant dewatering system for low-temperature flue gas pollutant removal according to claim 1, characterized in that: the ratio of the flow of the secondary refrigerant to the secondary refrigerant water removal tower (13) to the total flow of the outlet of the three-stage circulating pump (4) is 2-20%.

10. The secondary refrigerant dehydration method for removing the low-temperature pollutants in the flue gas is characterized by specifically comprising the following steps of:

the high-temperature flue gas enters a flue gas cooling tower (1), then is sequentially subjected to primary cooling, secondary cooling and tertiary cooling, the temperature of the cooled flue gas is reduced to be below 5 ℃, and then the cooled flue gas enters an adsorber (12), and the adsorber (12) performs desulfurization and denitration treatment on low-temperature dry flue gas;

the low-temperature dry flue gas with the sulfur and nitrate components removed is sent to a cold energy recoverer (6) to recover cold energy, the flue gas with the temperature of about 30-40 ℃ after the cold energy is recovered is divided into two paths, one path enters a secondary refrigerant water removal tower (13), and the other path is sent to a chimney and is directly discharged into the atmosphere to the chimney; meanwhile, a part of the secondary refrigerant from the secondary refrigerant buffer tank (11) enters the secondary refrigerant dewatering tower (13) and is in countercurrent contact with the dry flue gas, and after the dry flue gas takes away the moisture enriched in the secondary refrigerant, the secondary refrigerant flows back to the secondary refrigerant buffer tank (11).

Technical Field

The invention belongs to the technical field of flue gas pollutant purification, and particularly relates to a secondary refrigerant dehydration system and a dehydration method for removing low-temperature flue gas pollutants.

Background

In the field of low-temperature flue gas pollutant integrated removal, in order to improve the adsorption capacity of a unit adsorbent and reduce the loading volume of the adsorbent, the flue gas needs to be cooled to subzero temperature from high temperature in a grading manner, because the flue gas contains water, in the process of continuously cooling the flue gas below zero DEG C, if a method of indirectly exchanging heat between the flue gas and secondary refrigerant is adopted, along with the increase of the operation time, the moisture in the flue gas can be frozen at the flue gas side in a heat exchanger, the resistance of the heat exchanger is increased, even the flue gas is blocked, if a method of directly exchanging heat between the flue gas and the secondary refrigerant is adopted, along with the increase of the operation time, the secondary refrigerant can be diluted by the moisture in the flue gas, the freezing point of the secondary refrigerant is increased, fresh secondary refrigerant needs to be supplemented or replaced, the operation stability of a system is influenced, the consumption of the secondary refrigerant is increased, and the operation cost is increased.

The traditional secondary refrigerant dehydration method generally adopts drying agent drying or a direct heating evaporation method, a large amount of heat energy is consumed in the process of regeneration or heating evaporation of the drying agent after water absorption, energy waste is caused, a series of heating and cooling devices are required to be added, and the process is complicated. Therefore, the development of a novel secondary refrigerant dehydration system suitable for the integrated removal process of the low-temperature pollutants in the flue gas becomes the key point of research.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a secondary refrigerant dehydration system and a dehydration method for removing low-temperature pollutants in flue gas, wherein the system can effectively and continuously remove water in the secondary refrigerant, does not influence the stability of the operation of the integrated removal process of the low-temperature pollutants in the flue gas, does not increase the energy consumption of the system, and is simple and easy to realize.

In order to achieve the purpose, the invention adopts the following technical scheme: a secondary refrigerant dehydration system for removing low-temperature pollutants in flue gas comprises a flue gas cooling tower, wherein a primary cooling spray device, a secondary cooling spray device and a tertiary cooling spray device are sequentially arranged in the flue gas cooling tower along the flue gas airflow direction, a flue gas outlet of the flue gas cooling tower is connected with an absorber which is used for removing sulfur and nitrate components in the flue gas, an outlet of the absorber is connected with a flue gas inlet of a secondary refrigerant water removal tower through a flue gas pipeline, a circulating liquid outlet of the tertiary cooling spray device is connected with an inlet of a tertiary circulating pump through a secondary refrigerant buffer tank through a pipeline, an outlet of the tertiary circulating pump is divided into two paths, one path of the outlet is connected to a circulating liquid inlet of the tertiary circulating cooler, the other path of outlet is connected to a circulating liquid inlet of the secondary refrigerant water removal tower, and a circulating liquid inlet of the tertiary cooling spray device is communicated with a circulating liquid outlet of the tertiary circulating cooler, and a circulating liquid outlet of the secondary refrigerant water removal tower is connected to a secondary refrigerant buffer tank, and circulating liquid used by the three-stage cooling spraying device is secondary refrigerant.

The further scheme is that a cold energy recoverer is arranged on the flue gas pipeline and used for recovering cold energy in the flue gas.

The further scheme is that a circulating liquid outlet of the primary cooling spraying device is connected with a primary circulating pump through a pipeline, an outlet of the primary circulating pump is connected with a circulating liquid inlet of a primary circulating cooler, an outlet of the primary circulating cooler is connected with a circulating liquid inlet of a cold energy recoverer, a circulating liquid outlet of the cold energy recoverer is connected with a circulating liquid inlet of the primary cooling spraying device, and circulating liquid used by the primary cooling spraying device is cooling water.

The further scheme is that a cooling water inlet of the primary circulating cooler is connected with a circulating cooling water feeding pipeline of the power plant, and a cooling water outlet of the primary circulating cooler is connected with a circulating cooling water returning pipeline of the power plant.

The further scheme is that a circulating liquid outlet of the secondary cooling spraying device is connected with a secondary circulating pump through a pipeline, an outlet of the secondary circulating pump is connected with an inlet of a secondary circulating cooler, an outlet of the secondary circulating cooler is connected with a circulating liquid inlet of the secondary cooling spraying device, and circulating liquid used by the secondary cooling spraying device is cooling water.

The further proposal is that a cooling water inlet and outlet of the secondary circulating cooler is connected with an inlet and outlet of a first refrigerating machine; and a cooling water inlet and outlet of the third-stage circulating cooler is connected with an inlet and outlet of the second refrigerating machine.

In a further scheme, the secondary refrigerant is salt secondary refrigerant.

The further scheme is that a bypass pipeline connected with a chimney is arranged on the flue gas pipeline, and a flue gas outlet of the secondary refrigerant water removal tower is connected with the chimney.

The further scheme is that the ratio of the flow of the secondary refrigerant to the secondary refrigerant water tower to the total flow of the outlet of the primary circulating pump is 2-20%.

The secondary refrigerant dehydration method for removing the low-temperature pollutants in the flue gas specifically comprises the following steps:

the high-temperature flue gas enters a flue gas cooling tower and then sequentially undergoes primary cooling, secondary cooling and tertiary cooling, the temperature of the cooled flue gas is reduced to be below 5 ℃ and then the cooled flue gas enters an absorber, and the absorber performs desulfurization and denitration treatment on low-temperature dry flue gas;

the low-temperature dry flue gas with the sulfur and nitrate components removed is sent to a cold energy recoverer to recover cold energy, the flue gas at the temperature of about 30-40 ℃ after the cold energy is recovered is divided into two paths, one path enters a secondary refrigerant water removal tower, the other path goes to a chimney, and the flue gas goes to the chimney and is directly discharged into the atmosphere; meanwhile, a part of the secondary refrigerant from the secondary refrigerant buffer tank enters the secondary refrigerant dewatering tower and is in countercurrent contact with the dry flue gas, and after the dry flue gas takes away the moisture enriched in the secondary refrigerant, the secondary refrigerant flows back to the secondary refrigerant buffer tank.

Compared with the prior art, the invention has the beneficial effects that: the traditional secondary refrigerant dehydration method generally adopts a drying agent drying method or a direct heating evaporation method, a large amount of heat energy is consumed in the process of regeneration or heating evaporation of the drying agent after water absorption, energy waste is caused, a series of heating and cooling devices are required to be added, and the process is complicated.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

Reference numerals: 1. flue gas cooling tower, 2, first-level circulating pump, 3, second grade circulating pump, 4, tertiary circulating pump, 5, first-level circulative cooler, 6, cold volume recoverer, 7, second-level circulative cooler, 8, first refrigerator, 9, tertiary circulative cooler, 10, second refrigerator, 11, secondary refrigerant buffer tank, 12, adsorber, 13, secondary refrigerant remove the water tower.

Detailed Description

The present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments.

Referring to the attached figure 1, the secondary refrigerant dehydration system for removing low-temperature pollutants in flue gas comprises a flue gas cooling tower 1 connected with high-temperature flue gas after dust removal of a power plant, wherein a primary cooling spray device, a secondary cooling spray device and a tertiary cooling spray device are sequentially arranged in the flue gas cooling tower 1 along the direction of flue gas airflow from bottom to top, a circulating liquid outlet of the primary cooling spray device is connected with an inlet of a primary circulating pump 2, an outlet of the primary circulating pump 2 is connected with a circulating liquid inlet of a primary circulating cooler 5, a circulating liquid outlet of the primary circulating cooler 5 is communicated with a circulating liquid inlet of a cold energy recoverer 6, a circulating liquid outlet of the cold energy recoverer 6 goes to the circulating liquid inlet of the primary cooling spray device, and the primary circulating pump 2 is used for providing power so that the circulating liquid forms circulation in the primary cooling spray device; the cooling water inlet of the primary circulation cooler 5 is connected with the circulating cooling water feeding pipeline of the power plant, the cooling water outlet of the primary circulation cooler 5 is connected with the circulating cooling water return pipeline of the power plant, and the cooling capacity of the primary circulation cooler 5 is provided by the circulating cooling water of the power plant. The circulating liquid used by the first-stage cooling spraying device is cooling water, when flue gas enters the first-stage cooling spraying device from bottom to top, the cooling water sprays from top to bottom, the cooling water and the flue gas are in countercurrent contact for heat exchange, sufficient heat exchange is carried out between the cooling water and the flue gas, and the cooled flue gas enters the second-stage cooling spraying device after the temperature of the cooled flue gas is reduced to about 40 ℃.

In the embodiment, a circulating liquid outlet of the secondary cooling spray device is connected with an inlet of a secondary circulating pump 3, an outlet of the secondary circulating pump 3 is connected with a circulating liquid inlet of a secondary circulating cooler 7, a circulating liquid outlet of the secondary circulating cooler 7 goes to the circulating liquid inlet of the secondary cooling spray device, and the secondary circulating pump 3 is used for providing power to enable the circulating liquid to form circulation in the secondary cooling spray device; the refrigerant inlet of the secondary circulation cooler 7 is connected with the refrigerant outlet of the first refrigerator 8, the refrigerant outlet of the secondary circulation cooler 7 is connected with the refrigerant inlet of the first refrigerator 8, and the cold energy of the secondary circulation cooler 7 is provided by the first refrigerator 8. The circulating liquid used by the secondary cooling spray device is cooling water, when flue gas enters the secondary cooling spray device from bottom to top, the cooling water sprays from top to bottom, the cooling water and the flue gas are in countercurrent contact for heat exchange, sufficient heat exchange is carried out between the cooling water and the flue gas, and the cooled flue gas is cooled to about 5 ℃ and then enters the tertiary cooling spray device.

In this embodiment, a circulation liquid outlet of the tertiary cooling spray device is connected with the upper end of the secondary refrigerant buffer tank 11, the lower end of the secondary refrigerant buffer tank 11 is connected with an inlet of the tertiary circulating pump 4, an outlet of the tertiary circulating pump 4 is divided into two paths, one path is connected with the upper end of the secondary refrigerant water removal tower 13, the other path is connected with a circulation liquid inlet of the tertiary circulation cooler 9, wherein the flow of the secondary refrigerant going to the secondary refrigerant water removal tower 13 accounts for 2-20% of the total flow of the outlet of the tertiary circulating pump 4, and the amount of water in the flue gas absorbed by the secondary refrigerant can be judged by observing the change of the liquid level of the secondary refrigerant buffer tank 11, so that the flow of the secondary refrigerant going to the secondary refrigerant water removal tower 13 can be adaptively adjusted. A circulating liquid outlet of the third-stage circulating cooler 9 goes to a circulating liquid inlet of the third-stage cooling spray device, and the third-stage circulating pump 4 is used for providing power so that the circulating liquid forms circulation in the third-stage cooling spray device; a refrigerant inlet of the three-stage circulation cooler 9 is connected to a refrigerant outlet of the second refrigerator 10, and a refrigerant outlet of the three-stage circulation cooler 9 is connected to a refrigerant inlet of the second refrigerator 10. The circulating liquid used by the three-stage cooling spray device is a salt secondary refrigerant, preferably a calcium chloride solution, when the flue gas enters the three-stage cooling spray device from bottom to top, the secondary refrigerant sprays from top to bottom, the two are in countercurrent contact for heat exchange, sufficient heat exchange is carried out between cooling water and the secondary refrigerant, meanwhile, the secondary refrigerant is diluted by moisture in the flue gas to take away the moisture in the flue gas, and the cooled flue gas enters the absorber 12 after the temperature of the flue gas is reduced to be below 5 ℃.

In the embodiment, after low-temperature flue gas enters the adsorber 12, the adsorber 12 removes sulfur, nitrate and other components in the flue gas, then the flue gas outlet of the adsorber 12 is connected with the flue gas inlet of the cold energy recoverer 6, the clean cold flue gas goes to the cold energy recoverer 6 to recover cold energy, the temperature rises to about 30-40 ℃ after cold energy is recovered, the flue gas outlet of the cold energy recoverer 6 is divided into two paths, one path goes to a chimney and is directly discharged into the air, the other path goes to the lower end of the secondary refrigerant water removal tower 13 and is in countercurrent contact with the secondary refrigerant, the dry flue gas takes away water enriched in the secondary refrigerant and then is discharged into the air through the chimney, and the secondary refrigerant after water removal in the secondary refrigerant water removal tower 13 returns to the secondary refrigerant buffer tank 11.

The invention relates to a secondary refrigerant dehydration method for integrally removing low-temperature pollutants in flue gas, which specifically comprises the following steps:

the high-temperature flue gas enters a flue gas cooling tower 1 and then sequentially undergoes primary cooling, secondary cooling and tertiary cooling, the temperature of the cooled flue gas is reduced to be below 5 ℃ and then the cooled flue gas enters an adsorber 12, and the adsorber 12 performs desulfurization and denitration treatment on the low-temperature dry flue gas;

the low-temperature dry flue gas with the sulfur and nitrate components removed is sent to a cold energy recoverer 6 to recover cold energy, the flue gas with the temperature of about 30-40 ℃ after the cold energy is recovered is divided into two paths, one path enters a secondary refrigerant water removal tower 13, and the other path is sent to a chimney and is directly discharged into the atmosphere to the chimney; meanwhile, a part of the secondary refrigerant from the secondary refrigerant buffer tank 11 also enters the secondary refrigerant dewatering tower 13 and is in countercurrent contact with the dry flue gas, and after the dry flue gas takes away the moisture enriched in the secondary refrigerant, the secondary refrigerant flows back to the secondary refrigerant buffer tank 11.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.