Oxygen-enriched combustion flue gas dewatering system

Abstract

The utility model discloses an oxygen-enriched combustion flue gas water removal system which comprises a gas power furnace, a gas inlet pipe, a gas outlet pipe, a gas inlet pipe, a gas outlet pipe, a gas inlet pipe, a gas outlet pipe, a gas inlet pipe and a gas outlet pipe, and the gas power furnace is used for introducing gas and receiving combustion-supporting air formed by mixing circulating flue gas and oxygen; the flue gas heat collector is used for receiving the exhausted flue gas generated by the gas power furnace, exchanging heat with the flue gas cooled by the cooler and exhausting the flue gas into the atmosphere; and the cooling tower is arranged between the flue gas heat collector and the cooler, and the temperature of the flue gas entering the cooler is reduced by utilizing the gasification latent heat of water by forming spraying in the cooling tower by utilizing circulating outlet water of the cooler and making reverse contact with the flue gas from the flue gas heat collector. While the flue gas white smoke removal effect is guaranteed, heat in flue gas can be effectively recycled through matched use of the air pre-heater and the flue gas heat collector of the gas power furnace, the cooling tower is additionally arranged at the front end of a traditional cooler, the temperature of water entering the cooler can be reduced by fully utilizing gasification latent heat of the water, and the cooling effect is improved. Therefore, the cooler is energy-saving and water-saving.

Description

Technical Field

[0001] The utility model relates to the technical field of oxygen-enriched combustion of fuel gas, in particular to an oxygen-enriched combustion flue gas dehydration system for energy saving and flue gas dewhitening. Background Art

[0002] Oxygen-enriched combustion has attracted attention in the industry as an environmentally friendly combustion technology for energy conservation and carbon reduction. At present, there are relatively many oxygen-enriched combustion modifications for coal-fired furnaces, while gas-fired power furnaces using oxygen-enriched combustion technology are far less popular than oxygen-enriched coal-fired boilers, although gas-fired power furnaces can effectively achieve energy conservation and emission reduction, improve quality and increase efficiency. However, the oxygen-enriched transformation of gas-fired power furnaces has problems such as large equipment changes, low degree of reuse, and high hydrogen-carbon ratio of gas fuel. The resulting difficulty in flue gas dehydration and de-whitening has become an obstacle to the oxygen-enriched transformation of gas furnaces.

[0003] De-whitening is "de-whitening and water extraction", which involves cooling the flue gas and extracting water to make the flue gas meet environmental protection requirements such as exhaust temperature and humidity, and collecting the heat for reuse, thereby eliminating the "white smoke" at the chimney outlet. For example, the condensation dehumidification and reheating technology can be used to eliminate the whiteness of the smoke plume. First, the water vapor content of the flue gas is reduced by directly or indirectly cooling the flue gas, and then the exhaust temperature is increased through a heat exchange device to achieve the purpose of flue gas de-whitening.

[0004] There are many technical solutions for dehydration and dewhitening of flue gas and waste heat recovery of gas boilers in the prior art. For example, Chinese patent CN219976475U discloses a waste heat recovery system for flue gas of a gas boiler, including a flue gas cooler, a class A spray tower, a class B spray tower, a class A water-water heat exchanger, a class B water-water heat exchanger, a generating device, a liquid storage tank and a desalted water tank; the flue gas inlet of the flue gas cooler is connected to the flue gas outlet of the gas boiler economizer, the flue gas outlet of the flue gas cooler is connected to the flue gas inlet of the class A spray tower, the flue gas outlet of the class A spray tower is connected to the flue gas inlet of the class B spray tower, and the flue gas outlet of the class B spray tower is connected to the chimney; the outlet pipe of the desalted water tank is connected to the inlet pipe of the class A water-water heat exchanger, the outlet pipe of the class A water-water heat exchanger is connected to the inlet pipe of the class B water-water heat exchanger, and the outlet pipe of the class B water-water heat exchanger is connected to the inlet pipe of the generating device via the cooling device. This system can reduce the water vapor content in the exhaust gas and reduce the pollution caused by it. However, this type of solution is not aimed at the energy-saving transformation of the wet flue gas circulation oxygen-enriched combustion process, and it is difficult to effectively balance water removal and whitening with energy saving.

[0005] In the gas-oxygen-enriched combustion system, the high-temperature flue gas that has completed waste heat recovery is usually still much higher than the specified exhaust temperature. If it needs to be cooled to the specified exhaust temperature, a large amount of cooling water is required to achieve cooling. The water consumption can usually account for more than 30% of the total cooling water consumption in the plant, which brings huge cooling water consumption pressure to the refinery and causes large energy losses.

[0006] Therefore, there is an urgent need for an efficient and clean oxygen-enriched combustion flue gas dewatering system with good CO2 enrichment effect, low transformation cost and small energy loss.

[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 purpose of the utility model is to provide an oxygen-enriched combustion flue gas dewatering system, which can effectively recover the heat in the flue gas while ensuring the flue gas dewhitening effect through the coordinated use of the air preheater of the gas-fired furnace and the flue gas heat collector, and by adding a cooling tower at the front end of the traditional cooler, the latent heat of vaporization of water can be fully utilized to reduce the temperature entering the cooler, thereby achieving energy and water saving of the cooler.

[0009] Another purpose of the utility model is to provide an oxygen-enriched combustion flue gas dehumidification system, which can obtain high-concentration CO2 flue gas as a product for recycling through the setting of the combustion controller, and the combustion process will not produce NO x and SO x and other pollutants; it can also enable the system to have the ability to adaptively adjust according to the set values.

[0010] To achieve the above-mentioned purpose, the utility model provides an oxygen-enriched combustion flue gas dewatering system, comprising: a gas-fired furnace, which introduces fuel gas and receives combustion-supporting air formed by mixing circulating flue gas with oxygen, and is used for recycling the high-temperature flue gas generated by the gas-fired furnace; a flue gas heat collector, which receives the exhaust flue gas generated by the gas-fired furnace, and discharges it into the atmosphere after exchanging heat with the flue gas cooled by a cooler; a cooling tower, which is arranged between the flue gas heat collector and the cooler, and forms a spray in the cooling tower by utilizing the circulating water of the cooler and reversely contacts the flue gas from the flue gas heat collector, and utilizes the vaporization latent heat of water to reduce the temperature of the flue gas entering the cooler.

[0011] Furthermore, in the above technical solution, the cooling tower may be provided with: a spray head, which receives the circulating water from the cooler from the cooling water inlet and sprays it downward at an angle; a filler, which is arranged below the spray head and supported by a filler plate; a flue gas cyclone, which is arranged at the center of the cooling tower and below the filler; the flue gas cyclone sprayed upward and the cooling water sprayed downward contact in reverse at the filler.

[0012] Furthermore, in the above technical solution, a tilted cooling water guide plate may be provided at the bottom of the cooling tower to guide the cooling water after heat exchange to the cooling water outlet.

[0013] Furthermore, in the above technical solution, the gas-fired power furnace includes an air preheater, which can receive high-temperature flue gas from the gas-fired power furnace and divide the high-temperature flue gas into circulating flue gas and exhaust flue gas through the first induced draft fan.

[0014] Furthermore, in the above technical solution, the circulating flue gas can be mixed with oxygen through a static mixer, and the mixed gas enters the air preheater through a blower and exchanges heat with the high-temperature flue gas in the air preheater to serve as combustion-supporting air for the gas-fired power furnace.

[0015] Furthermore, in the above technical solution, the proportion of the circulating flue gas in the high-temperature flue gas from the air preheater can be controlled to be 55-70%.

[0016] Furthermore, in the above technical solution, the content of oxygen in the mixed gas of circulating flue gas and oxygen can be controlled to be 26-35%.

[0017] Furthermore, in the above technical solution, the gas-fired power furnace may be provided with a combustion controller for controlling the oxygen content in the exhaust gas during the oxygen-enriched combustion process to be between 2% and 4%; the combustion controller may also be used to control the furnace combustion temperature of the gas-fired power furnace through the flue gas emission, and to perform temperature alarm or interlock switching of the air combustion system according to the measured furnace temperature; the combustion controller may also be used to perform oxygen concentration alarm or interlock switching of the air combustion system according to the measured oxygen concentration of the combustion air.

[0018] Compared with the prior art, the utility model has the following beneficial effects:

[0019] 1) The utility model adds a flue gas heat exchanger and a cooling tower on the basis of the existing technology, so that the heat in the flue gas can be fully recovered and utilized through the air preheater and the flue gas heat exchanger, and at least 80% of the heat in the flue gas can be recovered. Among them, the flue gas heat exchanger uses the waste heat of the exhaust flue gas to heat the dehydrated saturated low-temperature flue gas, so that it is heated to become unsaturated flue gas while meeting the flue gas emission requirements; the heat exchange energy of the air preheater can be used to preheat the combustion-supporting air, thereby effectively improving the combustion efficiency and combustion performance of the gas-fired power furnace, and the heat loss of the gas-fired power furnace can be reduced by at least 20%;

[0020] 2) The utility model can effectively reduce the heat load of the cooler by setting up a cooling tower. Traditional oxygen-enriched combustion flue gas dehydration usually directly passes high-temperature flue gas into the cooler for heat exchange. The utility model makes full use of the latent heat of vaporization of water to reduce the temperature of the flue gas entering the cooler, which can save energy of the cooler by at least 70%. At the same time, the traditional process of water removal usually consumes a large amount of cooling water, which puts great pressure on the circulating water supply. The utility model can significantly reduce the amount of cooling water used and reduce the impact on the circulating water supply.

[0021] 3) The utility model configures a combustion controller for the gas-fired power furnace, which can control the oxygen content in the exhaust gas during the oxygen-enriched combustion process to between 2% and 4%, so that the CO2 volume fraction of the exhaust gas can reach more than 95%, and the high-concentration CO2 flue gas can be recycled as a product, and the combustion process does not produce NO x and SO x The combustion controller can also be used to control the combustion temperature of the furnace of the gas-fired power furnace through the flue gas emission, and to make a temperature alarm or interlock the switching of the air combustion system according to the measured furnace temperature; in addition, the combustion controller can also be used to make an oxygen concentration alarm or interlock the switching of the air combustion system according to the measured oxygen concentration of the combustion air. The utility model can monitor the combustion situation in real time, analyze the flue gas composition online, and adjust the wet circulation ratio of the flue gas through the setting of the combustion controller, so that the system has the ability to self-adapt according to the set value.

[0022] 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

[0023] Figure 1 It is a connection schematic diagram of the oxygen-enriched combustion flue gas dehydration system of the utility model.

[0024] Figure 2 It is a schematic diagram of the internal structure of a cooling tower in the oxygen-enriched combustion flue gas dewatering system of the utility model.

[0025] Description of main reference numerals:

[0026] 1-gas powered furnace, 10-air preheater, 101-first induced draft fan, 2-flue gas heat collector, 21-second induced draft fan, 3-cooling tower, 30-base, 31-flue gas outlet, 32-cooling water inlet, 33-cooling water sprinkler, 34-filler, 35-filler plate, 36-flue gas cyclone, 37-flue gas inlet, 38-cooling water outlet, 39-cooling water guide plate, 4-cooler, 41-cooling water pump, 5-static mixer, 51-blower, 6-chimney. 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] like Figure 1 As shown, the utility model provides an oxygen-enriched combustion flue gas dehydration system, which is applied in the wet flue gas circulating oxygen-enriched combustion process, can not only achieve the dehydration and whitening of flue gas, but also save water and effectively reduce energy consumption. It at least includes: a gas-powered furnace 1, a flue gas heat collector 2 and a cooling tower 3.

[0032] Further Figure 1 As shown, the gas-fired furnace 1 may also include an air preheater 10 and a static mixer 5. The air preheater 10 may receive high-temperature flue gas from the gas-fired furnace 1 and divide the high-temperature flue gas into circulating flue gas and exhaust flue gas through the first induced draft fan 101. The circulating flue gas may be mixed with oxygen through the static mixer 5. The mixed gas (at this time, the temperature of the high-temperature flue gas has been reduced due to the mixing of the gases) enters the cold side of the air preheater 10 through the blower 51 and is used as the combustion-supporting wind of the gas-fired furnace after heat exchange with the high-temperature flue gas on the hot side of the air preheater. The combustion-supporting wind containing oxygen enters the gas-fired furnace 1 and undergoes oxygen-enriched combustion with the introduced gas. The gas may be other gas fuels such as natural gas and refinery dry gas. The oxygen used as an oxidant for oxygen-enriched combustion may be oxygen produced as a byproduct of hydrogen production by electrolysis of water. The utility model uses the circulating flue gas as a diluent for oxygen-enriched combustion.

[0033] Furthermore, in the high-temperature flue gas from the air preheater, the proportion of circulating flue gas is preferably controlled to be 55-70% (the remaining proportion is exhaust flue gas). This part of the circulating flue gas and the by-product pure oxygen can be evenly mixed in the high-efficiency static mixer 5, and the proportion of circulating flue gas can be controlled by the flow rate of exhaust flue gas. In the mixed gas of circulating flue gas and oxygen, the proportion of oxygen content is preferably 26-35%, and the amount of pure oxygen can be controlled and adjusted by a flow meter, so as to ensure that the furnace temperature of oxygen-enriched combustion is basically consistent with the furnace temperature of air-assisted combustion. The evenly mixed combustion-supporting air is sent to the air preheater 10 for heat exchange through the blower 51, and then enters the gas-fired power furnace 1 of the utility model to burn with the gas, realizing oxygen-enriched combustion while recycling part of the high-temperature flue gas.

[0034] The flue gas heat exchanger 2 of the utility model is used to receive the exhaust flue gas (i.e., 30% to 45% of the high-temperature flue gas) generated by the gas-fired power furnace 1, and then discharge it into the atmosphere after heat exchange with the flue gas cooled by the cooler 4 (i.e., it is discharged to the chimney 6 through the second induced draft fan 21). The cooling tower 3 of the utility model is arranged between the flue gas heat exchanger 2 and the cooler 4. By using the circulating water of the cooler 4 to form a spray in the cooling tower 3 and reversely contacting with the flue gas from the hot side outlet of the flue gas heat exchanger 2, the latent heat of gasification of water can be used to effectively reduce the temperature of the flue gas entering the cooler 4. Compared with the prior art in which the flue gas directly enters the cooler, water and energy can be saved. Specifically, this part of the exhaust flue gas is sent to the flue gas heat exchanger 2 through the first induced draft fan 101 for further heat recovery. The flue gas heat exchanger 2 can use the waste heat of the exhaust flue gas to heat the dehydrated saturated low-temperature flue gas (from the cooler 4) to above 85°C, so that it is heated to become unsaturated flue gas while meeting the flue gas emission requirements. The flue gas temperature from the hot side outlet of the flue gas heat exchanger 2 can still reach about 150°C. This part of the flue gas is passed into the cooling tower 3 to spray an appropriate amount of cooling water. The latent heat of vaporization of the cooling water can be used to reduce the flue gas temperature to below 100°C. The saturated wet flue gas is then passed into the cooler 4 to remove water. The low-temperature flue gas after water removal is heated by the flue gas heat exchanger 2 and then sent to the chimney 6 for discharge.

[0035] Further Figure 2 As shown, preferably but not restrictively, a spray head 33, a filler 34 and a flue gas cyclone 36 may be provided in the cooling tower 3. Among them, the spray head 33 can receive the circulating water of the cooler from the cooling water inlet 32 ​​and spray it downward at an angle; the filler 34 is arranged below the spray head 33 and supported by the filler plate 35; the flue gas cyclone 36 is arranged at the center position in the cooling tower 3 and is located below the filler 34. The flue gas cyclone sprayed upward can contact the cooling water sprayed downward in reverse at the filler 34. Furthermore, a cooling water guide plate 39 arranged obliquely at the bottom of the cooling tower 3 can be provided for guiding the cooling water after heat exchange to the cooling water outlet 38. The flue gas inlet 37 is arranged at the lower part of the cooling tower 3, the flue gas outlet 31 is arranged at the top of the tower, and the base 30 is provided at the bottom of the tower.

[0036] The utility model adds a flue gas heat collector and a cooling tower, and the flue gas can fully recycle the heat in the flue gas through the air preheater and the flue gas heat collector, and at least 80% of the heat in the flue gas can be recycled. Among them, the flue gas heat collector can heat the dehydrated saturated low-temperature flue gas by using the waste heat of the exhaust flue gas, so that it can be heated to become unsaturated flue gas while meeting the flue gas emission requirements; the heat exchange energy of the air preheater can be used to preheat the combustion-supporting air, thereby effectively improving the combustion efficiency and combustion performance of the gas-fired power furnace, and the heat loss of the gas-fired power furnace can be reduced by at least 20%; the setting of the cooling tower can effectively reduce the heat load of the cooler, and the traditional oxygen-enriched combustion flue gas dehydration usually directly passes the high-temperature flue gas into the cooler for heat exchange, and the utility model makes full use of the vaporization latent heat of water to reduce the temperature of the flue gas entering the cooler, which can at least save energy for the cooler by 70%; at the same time, the traditional process of water removal usually consumes a large amount of cooling water, which brings huge pressure to the circulating water supply of the plant area, and the utility model can significantly reduce the amount of cooling water and reduce the impact on the circulating water supply.

[0037] Furthermore, preferably but not restrictively, the gas-fired power furnace 1 is provided with a combustion controller (not shown in the figure), which can be used to control the oxygen content in the exhaust gas during the oxygen-enriched combustion process to between 2% and 4% (which can be controlled by adjusting the pure oxygen flow entering the static mixer), so that the CO2 volume fraction of the exhaust gas can reach more than 95%, and the high-concentration CO2 flue gas can be recycled as a product, and the combustion process does not produce NO x and SO x and other pollutants; in addition, the combustion controller can also be used to control the furnace combustion temperature of the gas-fired power furnace through the flue gas emission, and to perform temperature alarm or interlock switching of the air combustion system according to the measured furnace temperature. For example, when the furnace temperature reaches 2000°C, set the furnace temperature alarm; when the furnace temperature reaches 2200°C, set the boiler interlock switching air combustion system, gradually replenish air, and shut down oxygen; furthermore, the combustion controller can also be used to perform oxygen concentration alarm or interlock switching of the air combustion system according to the measured oxygen concentration of the combustion air. For example, when the oxygen concentration of the combustion air reaches 32%, set the combustion air oxygen concentration alarm; when the oxygen concentration reaches 35%, set the boiler interlock switching air combustion system, gradually replenish air, and shut down oxygen.

[0038] The utility model configures a combustion controller for the gas powered furnace, so as to monitor the combustion situation in real time, analyze the smoke composition online, and adjust the smoke wet circulation ratio, so that the system has the ability of adaptively adjusting according to the set value.

[0039] 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 oxygen-enriched combustion flue gas dehumidification system, characterized in that: include: A gas-fired power furnace, which is fed with gas and receives combustion-supporting air formed by mixing circulating flue gas with oxygen, and is used for recycling the high-temperature flue gas generated by the gas-fired power furnace; A flue gas heat collector receives the exhaust flue gas generated by the gas-fired power furnace, exchanges heat with the flue gas cooled by the cooler, and then discharges it into the atmosphere; The cooling tower is arranged between the flue gas heat collector and the cooler. The circulating water of the cooler is used to form a spray in the cooling tower and to contact the flue gas from the flue gas heat collector in reverse direction. The latent heat of vaporization of water is used to reduce the temperature of the flue gas entering the cooler.

2. The oxygen-enriched combustion flue gas dehumidification system according to claim 1, characterized in that: The cooling tower is provided with: A spray head receives circulating water from the cooler from a cooling water inlet and sprays the water downwardly at an angle; A packing material, which is arranged below the spray head and supported by a packing plate; The flue gas cyclone sprayer is arranged at the center of the cooling tower and below the filler; the flue gas cyclone sprayed upwards contacts the cooling water sprayed downwards in reverse directions at the filler.

3. The oxygen-enriched combustion flue gas dehumidification system according to claim 2, characterized in that: The bottom of the cooling tower is provided with an inclined cooling water guide plate for guiding the cooling water after heat exchange to the cooling water outlet.

4. The oxygen-enriched combustion flue gas dehumidification system according to claim 1, characterized in that: The gas-fired power furnace comprises an air preheater, which receives high-temperature flue gas from the gas-fired power furnace and divides the high-temperature flue gas into the circulating flue gas and the exhaust flue gas through a first induced draft fan.

5. The oxygen-enriched combustion flue gas dehumidification system according to claim 4, characterized in that: The circulating flue gas is mixed with oxygen through a static mixer, and the mixed gas enters the air preheater through a blower and serves as the combustion-supporting air of the gas-fired power furnace after heat exchange with the high-temperature flue gas in the air preheater.

6. The oxygen-enriched combustion flue gas dehumidification system according to claim 4, characterized in that: The circulating flue gas accounts for 55-70% of the high-temperature flue gas from the air preheater.

7. The oxygen-enriched combustion flue gas dehumidification system according to claim 5, characterized in that: In the mixed gas of the circulating flue gas and oxygen, the content of oxygen accounts for 26-35%.

8. The oxygen-enriched combustion flue gas dehumidification system according to claim 7, characterized in that: The gas powered furnace is provided with a combustion controller for controlling the oxygen content in the exhaust gas generated during the oxygen-enriched combustion process to be between 2% and 4%.

9. The oxygen-enriched combustion flue gas dehumidification system according to claim 8, characterized in that: The combustion controller is also used to control the furnace combustion temperature of the gas-fired power furnace through the flue gas emission, and to perform temperature alarm or interlock switching of the air combustion system according to the measured furnace temperature.

10. The oxygen-enriched combustion flue gas dehumidification system according to claim 9, characterized in that: The combustion controller is also used to issue an oxygen concentration alarm or interlock and switch the air combustion system according to the measured oxygen concentration of the combustion-supporting air.

Images