Ammonia desulfurization flue gas aerosol removal system

Abstract

The utility model discloses an ammonia desulfurization flue gas aerosol removal system, which comprises an LNG (liquefied natural gas) cooling unit which comprises a first circulating heat-taking heat exchanger and a second circulating heat-taking heat exchanger which are connected in series on an LNG pipeline and is used for cooling flue gas at an inlet of a first desulfurization tower and desulfurization slurry at an outlet of the first desulfurization tower; and the tower-front heat exchange unit comprises a tower-front heat exchanger and a desulfurization slurry heat exchanger which are connected to a refrigerant pipeline in series, the tower-front heat exchanger exchanges heat between the refrigerant from the first circulation heat removal heat exchanger and the inlet flue gas, and the desulfurization slurry heat exchanger exchanges heat between the refrigerant from the second circulation heat removal heat exchanger and the outlet desulfurization slurry. According to the LNG cold energy gradient utilization device, aerosol can be effectively removed through LNG cold energy, and gradient utilization of the LNG cold energy can be achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of energy-saving and environmental protection engineering, in particular to an ammonia-based flue gas aerosol removal system utilizing LNG cold energy. Background Art

[0002] In recent years, more and more attention has been paid to the use of efficient and clean energy. LNG (Liquefied Natural Gas) is not only easy to store and transport, but also the cleanest fossil energy at present, and its consumption is growing rapidly. The liquefaction temperature of LNG under normal pressure is -162℃, and each kilogram of LNG releases about 830kJ of cold energy during the gasification process. If this cold energy is used to generate electricity, assuming that the efficiency reaches 100%, the cold energy that can be used per ton of LNG is equivalent to about 231kW·h of electricity. It can be seen that the use of LNG cold energy has huge potential for energy saving and consumption reduction.

[0003] At present, the main ways to utilize LNG cold energy include low-temperature power generation, air separation, dry ice production, low-temperature crushing and rubber recovery, etc. Since the temperature of LNG cold energy rises from -162℃ to 10℃ during the utilization process, there is a large temperature rise difference. At present, the single-stage or multi-stage utilization process of LNG cold energy still has the problem of incomplete cold energy utilization and low utilization efficiency.

[0004] The existing technical solutions for utilizing LNG cold energy in the field of low-temperature power generation are, for example, Chinese patent CN202868298U, which discloses a LNG cold energy cascade utilization system, which mainly includes: LNG storage tank, BOG condensing device, air separation device, liquid carbon dioxide production device, cold energy power generation device, cold storage and flow regulating device; LNG storage tank is connected to BOG condensing device, BOG condensing device is connected to the primary flow regulating device, the primary flow regulating device is respectively connected to the air separation device, cold energy power generation device and secondary flow regulating device; the air separation device is connected to the liquid carbon dioxide production device through a pipeline, the liquid carbon dioxide production device is connected to the gas supply pretreatment system through a heat exchanger, and the heat exchanger is connected to the intermediate cold storage; the cold energy power generation device is connected to the gas supply pretreatment system through a heat exchanger, and the heat exchanger is connected to the deep freezing storage and the low-temperature fresh-keeping storage in sequence; the secondary flow regulating device is connected to the vaporizer, the vaporizer is connected to the buffer zone, and the buffer zone is connected to the gas supply pretreatment system. After utilizing LNG cold energy for power generation, this type of solution still has the problem of underutilization of some cold energy.

[0005] The ammonia desulfurization process has the advantages of high desulfurization efficiency and absorbent utilization, and resource utilization of by-products. However, in the process of ammonia desulfurization, there is a phenomenon of secondary generation of aerosol particles, which causes the concentration of particles in the flue gas after desulfurization to exceed the standard, and the emission of flue gas into the atmosphere can aggravate the particle pollution problem.

[0006] Therefore, there is an urgent need for a system that can fully utilize the cold energy of LNG in the ammonia desulfurization process and effectively remove aerosols, so as to achieve the cascade utilization of LNG cold energy.

[0007] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to a person skilled in the art. Utility Model Content

[0008] The utility model aims to provide an ammonia flue gas aerosol removal system, which can not only effectively remove aerosols through LNG cold energy, but also realize the cascade utilization of LNG cold energy.

[0009] To achieve the above-mentioned purpose, the utility model provides an ammonia-based flue gas aerosol removal system, comprising: an LNG cooling unit, which comprises a first circulation heat exchanger and a second circulation heat exchanger connected in series on the LNG pipeline, and is used to cool the flue gas at the inlet of the first desulfurization tower and the desulfurization slurry at the outlet of the first desulfurization tower; a pre-tower heat exchange unit, which comprises a pre-tower heat exchanger and a desulfurization slurry heat exchanger connected in series on the refrigerant pipeline, the pre-tower heat exchanger exchanges heat between the refrigerant from the first circulation heat exchanger and the inlet flue gas, and the desulfurization slurry heat exchanger exchanges heat between the refrigerant from the second circulation heat exchanger and the outlet desulfurization slurry.

[0010] Furthermore, in the above technical solution, the first desulfurization tower is provided with a flue gas inlet and a flue gas outlet, the flue gas inlet is provided at the lower part of the tower, and the flue gas outlet is provided at the top of the tower.

[0011] Furthermore, in the above technical solution, the first desulfurization tower is provided with a desulfurization slurry inlet and a desulfurization slurry outlet, and the desulfurization slurry heat exchanger is arranged on the pipeline between the desulfurization slurry inlet and outlet.

[0012] Furthermore, in the above technical scheme, the system of the utility model may also include a post-tower deep purification unit, which further includes: a second desulfurization tower, which is connected to the flue gas outlet of the first desulfurization tower, for receiving the flue gas from the first desulfurization tower and spraying circulating cooling water; a cold wash heat exchanger, which is connected in series on the LNG pipeline and receives the gasified LNG to provide heat exchange for the circulating cooling water.

[0013] Furthermore, in the above technical solution, the second desulfurization tower is provided with a cooling water inlet and a liquid phase outlet; and the cold wash heat exchanger is arranged on the pipeline between the cooling water inlet and the liquid phase outlet.

[0014] Furthermore, in the above technical solution, the circulating cooling water is supplied from a water tank, which is connected in parallel to the pipeline of the liquid phase outlet.

[0015] Furthermore, in the above technical solution, a first water pump and a second water pump are respectively provided on the pipeline of the liquid phase outlet and the supply pipeline of the water tank.

[0016] Furthermore, in the above technical solution, a gas-liquid separator may be provided on the flue gas outlet pipeline of the second desulfurization tower.

[0017] Furthermore, in the above technical solution, a smoke-smoke heat exchanger may be provided on the smoke outlet pipeline of the gas-liquid separator for heat exchange between the high-temperature smoke from the outside and the outlet smoke of the gas-liquid separator.

[0018] Furthermore, in the above technical solution, both the LNG pipeline and the refrigerant pipeline are circulation pipelines.

[0019] Compared with the prior art, the utility model has the following beneficial effects:

[0020] 1) The utility model utilizes the cooling capacity provided by the LNG cooling unit to cool down the inlet flue gas of the first desulfurization tower (i.e., the first-stage utilization), so that the inlet flue gas temperature drops from the original 120°C to about 80°C, which can reduce the number concentration and mass concentration of ammonia aerosol emissions by about 20% and 30% respectively; at the same time, the cooling capacity provided by the LNG cooling unit can reduce the temperature of the desulfurization slurry to 30°C (i.e., the second-stage utilization), so that the number concentration of ammonia aerosol emissions drops by about 50%, and the mass concentration is reduced by about 30%, thereby eliminating and reducing the formation of aerosols and pollution to the environment;

[0021] 2) The utility model uses a post-desulfurization tower deep purification unit, and uses circulating cooling water in the second desulfurization tower to reduce the desulfurized flue gas temperature from 51.5°C to 35°C (i.e., third-stage utilization), so that the number concentration of aerosol particles in the flue gas is reduced by about 70%, and the mass concentration is reduced by about 80%. Compared with the existing desulfurization device, due to the introduction of the third-stage utilization of LNG cooling (the third-stage utilization gasifies LNG into NG for utilization), the flue gas temperature can be further effectively reduced, while reducing the volume of the heat exchanger and reducing investment;

[0022] 3) The utility model can use the smoke-smoke heat exchanger to preliminarily cool down the high-temperature flue gas before it enters the pre-tower heat exchanger, which can effectively improve the heat exchange efficiency of the pre-tower heat exchanger; on the other hand, it can appropriately heat up the flue gas separated by the gas-liquid separator before it is discharged into the atmosphere, thereby achieving the effect of "eliminating white smoke", effectively utilizing waste heat, and realizing energy saving.

[0023] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, and at the same time to make the above and other purposes, technical features and advantages of the utility model easier to understand, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a connection schematic diagram of the ammonia flue gas aerosol removal system of the utility model.

[0025] Description of main reference numerals:

[0026] 1-first desulfurization tower, 2-first circulating heat exchanger, 3-second circulating heat exchanger, 4-front-tower heat exchanger, 5-desulfurization slurry heat exchanger, 6-second desulfurization tower, 61-first water pump, 62-first water pump inlet valve, 63-first water pump outlet valve, 7-cold wash heat exchanger, 70-circulating cooling water tank, 71-second water pump, 72-second water pump inlet valve, 73-second water pump outlet valve, 8-gas-liquid separator, 9-smoke-smoke heat exchanger. DETAILED DESCRIPTION

[0027] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0028] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0029] In this document, for the convenience of description, spatial relative terms such as "below", "below", "down", "above", "above", "upper", etc. may be used to describe the relationship between one element or feature and another element or feature in the accompanying drawings. It should be understood that the spatial relative terms are intended to include different orientations of the object in use or operation in addition to the orientation depicted in the figure. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used in this document should be interpreted accordingly.

[0030] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable.

[0031] The utility model provides an ammonia-based flue gas aerosol removal system, which at least includes an LNG cooling unit and a pre-tower heat exchange unit. The LNG cooling unit at least includes a first circulation heat exchanger 2 and a second circulation heat exchanger 3 connected in series on the LNG pipeline, which are used to cool the inlet flue gas of the first desulfurization tower 1 and the desulfurization slurry at the outlet of the first desulfurization tower 1. The pre-tower heat exchange unit at least includes a pre-tower heat exchanger 4 and a desulfurization slurry heat exchanger 5 connected in series on the refrigerant pipeline, the pre-tower heat exchanger 4 exchanges heat with the refrigerant from the first circulation heat exchanger 2 and the inlet high-temperature flue gas of the first desulfurization tower 1, and the desulfurization slurry heat exchanger 5 exchanges heat with the refrigerant from the second circulation heat exchanger 3 and the desulfurization slurry at the outlet of the first desulfurization tower 1. Specifically, the first desulfurization tower 1 is provided with a flue gas inlet and a flue gas outlet, the flue gas inlet is arranged in the lower middle part of the tower, and the flue gas outlet is arranged at the top of the tower. The first desulfurization tower 1 is also provided with a desulfurization slurry inlet (located at the upper part of the tower) and a desulfurization slurry outlet (located at the lower part of the tower), and a desulfurization slurry heat exchanger 5 is arranged on the pipeline between the desulfurization slurry inlet and outlet.

[0032] Further references Figure 1 The specific connection relationship between the LNG cooling unit, the front heat exchange unit and the first desulfurization tower 1 is as follows: the hot inlet of the front heat exchanger 4 is connected to the flue gas pipeline, the hot outlet is connected to the first desulfurization tower 1 through the flue gas pipeline, the cold inlet is connected to the hot outlet of the first circulating heat exchanger 2 through the circulating refrigerant liquid pipeline, and the cold outlet is connected to the hot inlet of the second circulating heat exchanger 3 through the circulating refrigerant liquid pipeline. The cold inlet of the desulfurization slurry heat exchanger 5 is connected to the hot outlet of the second circulating heat exchanger 3 through the circulating refrigerant liquid pipeline, and the cold outlet is connected to the circulating refrigerant liquid return tank pipeline (that is, Figure 1 The refrigerant in the desulfurization slurry heat exchanger 5 is connected to the slurry extraction pipeline at the bottom of the first desulfurization tower 1, and the hot outlet is connected to the desulfurization slurry inlet of the first desulfurization tower through the desulfurization slurry pipeline. A flue gas outlet is provided at the top of the first desulfurization tower 1, which is connected to the flue gas pipeline.

[0033] The heat exchange unit in front of the first desulfurization tower of the utility model utilizes the cooling capacity provided by the LNG cooling unit to cool the inlet flue gas of the first desulfurization tower, so that the inlet flue gas temperature drops from the original 120°C to about 80°C, which can reduce the number concentration and mass concentration of ammonia aerosol emissions by about 20% and 30% respectively; at the same time, the cooling capacity provided by the LNG cooling unit can reduce the temperature of the desulfurization slurry to 30°C, so that the number concentration of ammonia aerosol emissions drops by about 50%, and the mass concentration is reduced by about 30%, thereby eliminating and reducing the formation of aerosols and pollution to the environment.

[0034] Further Figure 1As shown, preferably but not restrictively, the ammonia flue gas aerosol removal system of the utility model also includes a post-tower deep purification unit, which further includes a second desulfurization tower 6 and a cold wash heat exchanger 7. Among them, the second desulfurization tower 6 is connected to the flue gas outlet of the first desulfurization tower 1, and is used to receive the flue gas from the first desulfurization tower and spray circulating cooling water (playing the role of secondary cooling). The cold wash heat exchanger 7 is connected in series to the LNG pipeline and provides heat exchange for the circulating cooling water (that is, the third-level utilization of LNG is realized on the basis of the first circulating heat exchanger 2 and the second circulating heat exchanger 3). Specifically, the second desulfurization tower 6 is provided with a cooling water inlet (located at the top of the tower) and a liquid phase outlet (located at the bottom of the tower). The cold wash heat exchanger 7 is arranged on the pipeline between the cooling water inlet and the liquid phase outlet. The circulating cooling water is supplied from the water tank 70, and the water tank 70 is connected in parallel to the pipeline of the liquid phase outlet.

[0035] In the post-desulfurization tower deep purification unit, the desulfurized flue gas temperature can be reduced from 51.5°C to 35°C by using circulating cooling water (by spraying) in the second desulfurization tower, so that the number concentration of aerosol particles in the flue gas is reduced by about 70% and the mass concentration is reduced by about 80%. Compared with the existing desulfurization device, due to the introduction of the third-level utilization of LNG cooling capacity, the flue gas temperature can be further effectively reduced, while the volume of the heat exchanger is reduced and the investment is reduced. Furthermore, a first water pump 61 is provided on the pipeline of the liquid phase outlet, and the liquid phase after spraying in the second desulfurization tower 6 can be pumped out and recycled through the first water pump 61. A second water pump 71 is provided on the supply pipeline of the water tank 70, which can provide sufficient circulating cooling water in the early stage of spraying. The first water pump 61 is provided with a first water pump inlet valve 62 and a first water pump outlet valve 63 upstream and downstream, respectively, and the second water pump 71 is provided with a second water pump inlet valve 72 and a second water pump outlet valve 73 upstream and downstream.

[0036] Further references Figure 1 , the specific connection relationship of each device in the post-tower deep purification unit is as follows: After the second desulfurization tower 6 receives the cooled flue gas from the top of the first desulfurization tower 1, it is further cooled by spraying. The outlet of the circulating cooling water tank 70 is connected to the second water pump inlet valve 72, the second water pump 71, and the second water pump outlet valve 73 in sequence; after the circulating cooling water enters the second desulfurization tower 6 for condensation circulation, it passes through the first water pump inlet valve 62, the first water pump 61, and the first water pump outlet valve 63 respectively. The pipelines where the first water pump and the second water pump are located are arranged in parallel, and the parallel circulating cooling water pipeline is connected to the hot inlet of the cold wash heat exchanger 7, and the hot outlet of the cold wash heat exchanger 7 returns to the second desulfurization tower 6 through the circulating cooling water pipeline. The heat exchange of the cold wash heat exchanger utilizes the third-stage heat exchange of LNG (gasified NG heat exchange), that is, the cold inlet of the cold wash heat exchanger 7 is connected to the cold outlet of the second circulating heat exchanger 3, and the cold outlet of the cold wash heat exchanger 7 is connected to the NG return pipeline (that is Figure 1It should be noted here that in order to avoid the temperature of the circulating cooling water being lowered below the freezing point, the LNG coming out of the cold outlet of the second circulating heat exchanger 3 can be gasified and processed into NG before entering the cold wash heat exchanger 7.

[0037] Further Figure 1 As shown, a gas-liquid separator 8 is provided on the flue gas outlet pipeline of the second desulfurization tower 6. A smoke-smoke heat exchanger 9 is provided on the flue gas outlet pipeline of the gas-liquid separator 8, which is used to perform heat exchange between the high-temperature flue gas from the outside and the outlet flue gas of the gas-liquid separator 8. On the one hand, the high-temperature flue gas before entering the pre-tower heat exchanger 4 can be initially cooled down to improve the heat exchange efficiency of the pre-tower heat exchanger. On the other hand, the flue gas separated by the gas-liquid separator 8 can be appropriately heated before being discharged into the atmosphere, thereby achieving the effect of "eliminating white smoke". The smoke-smoke heat exchanger can effectively increase the exhaust flue gas temperature, utilize waste heat, and achieve energy saving.

[0038] The foregoing description of specific exemplary embodiments of the utility model is for the purpose of illustration and illustration. These descriptions are not intended to limit the utility model to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the utility model and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the utility model and various different options and changes. Any simple modifications, equivalent changes and modifications made to the above exemplary embodiments should fall within the scope of protection of the utility model.

Claims

1. An ammonia flue gas aerosol removal system, characterized in that: include: The LNG cooling unit includes a first circulation heat exchanger and a second circulation heat exchanger connected in series on the LNG pipeline, and is used to cool the flue gas at the inlet of the first desulfurization tower and the desulfurized slurry at the outlet of the first desulfurization tower; The front-tower heat exchange unit includes a front-tower heat exchanger and a desulfurization slurry heat exchanger connected in series on the refrigerant pipeline. The front-tower heat exchanger exchanges heat between the refrigerant from the first circulating heat exchanger and the imported flue gas, and the desulfurization slurry heat exchanger exchanges heat between the refrigerant from the second circulating heat exchanger and the exported desulfurization slurry.

2. The ammonia flue gas aerosol removal system according to claim 1 is characterized in that: The first desulfurization tower is provided with a flue gas inlet and a flue gas outlet. The flue gas inlet is arranged at the lower part of the tower, and the flue gas outlet is arranged at the top of the tower.

3. The ammonia flue gas aerosol removal system according to claim 1 is characterized in that: The first desulfurization tower is provided with a desulfurization slurry inlet and a desulfurization slurry outlet, and the desulfurization slurry heat exchanger is arranged on the pipeline between the desulfurization slurry inlet and outlet.

4. The ammonia flue gas aerosol removal system according to claim 1 is characterized in that: The system also includes a post-tower deep purification unit, which further includes: a second desulfurization tower, connected to the flue gas outlet of the first desulfurization tower, for receiving the flue gas from the first desulfurization tower and spraying circulating cooling water; The cold wash heat exchanger is connected in series to the LNG pipeline and receives the gasified LNG to provide heat exchange for the circulating cooling water.

5. The ammonia flue gas aerosol removal system according to claim 4 is characterized in that: The second desulfurization tower is provided with a cooling water inlet and a liquid phase outlet; the cold wash heat exchanger is arranged on the pipeline between the cooling water inlet and the liquid phase outlet.

6. The ammonia flue gas aerosol removal system according to claim 5 is characterized in that: The circulating cooling water is supplied from a water tank which is connected in parallel to the pipeline of the liquid phase outlet.

7. The ammonia flue gas aerosol removal system according to claim 6 is characterized in that: A first water pump and a second water pump are respectively provided on the pipeline of the liquid phase outlet and the supply pipeline of the water tank.

8. The ammonia flue gas aerosol removal system according to claim 4 is characterized in that: A gas-liquid separator is provided on the flue gas outlet pipeline of the second desulfurization tower.

9. The ammonia flue gas aerosol removal system according to claim 8, characterized in that: A smoke-smoke heat exchanger is provided on the smoke outlet pipeline of the gas-liquid separator, which is used to perform heat exchange between the high-temperature smoke from the outside and the outlet smoke of the gas-liquid separator.

10. The ammonia flue gas aerosol removal system according to claim 1, characterized in that: The LNG pipeline and the refrigerant pipeline are both circulation pipelines.

Images