CN215637275U - Dew point corrosion resistant low-temperature flue gas heat exchanger assembly - Google Patents
Dew point corrosion resistant low-temperature flue gas heat exchanger assembly Download PDFInfo
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- CN215637275U CN215637275U CN202122050206.3U CN202122050206U CN215637275U CN 215637275 U CN215637275 U CN 215637275U CN 202122050206 U CN202122050206 U CN 202122050206U CN 215637275 U CN215637275 U CN 215637275U
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
A dew point corrosion resistant low-temperature flue gas heat exchanger assembly comprises a heat exchanger body and a condensed water collecting pool, wherein a flue gas inlet channel is arranged at one end of the heat exchanger body, a flue gas inlet is formed in the flue gas inlet channel, and a spraying device is arranged in the flue gas inlet channel; the other end of the heat exchanger body is provided with a smoke outlet channel; and a water outlet of the condensed water collecting tank is connected with a spraying device through a condensed water circulating pipe. On one hand, the flue gas-condensed water circulation can be utilized, the concentration and the temperature of acid are greatly reduced, and the corrosion of two dew points of sulfuric acid and nitric acid generated by the flue gas is avoided; on the other hand, the heat of flue gas can make full use of, improves the energy utilization rate of flue gas, but also can wash heat exchanger body deposition in succession through the condensate water that forms behind the flue gas heat transfer, ensures that heat exchange efficiency is stable.
Description
Technical Field
The utility model relates to a flue gas heat exchanger component, in particular to a low-temperature flue gas heat exchanger component capable of resisting dew point corrosion.
Background
The existing heat exchangers, such as plate heat exchangers and tube-fin heat exchangers, have the characteristics of small volume, high heat exchange efficiency and good pressure resistance, and can be applied to efficient recovery of flue gas heat in narrow and small space environments.
However, when sulfur compounds are burned, acidic gases such as sulfur dioxide and sulfur trioxide are generated in the flue gas. In particular, sulfur trioxide is easy to combine with water vapor in flue gas to generate sulfuric acid fog drops which are condensed on the surface of a heat exchanger to generate serious corrosion, namely sulfuric acid dew point corrosion or dew point corrosion for short. The flue gases of civil or industrial gas, which contain different amounts of sulfur trioxide, undergo sulfuric acid condensation and the temperature at which dew point corrosion occurs starts in the temperature range 102-150 c and below, and the temperature range of corrosion continues up to the temperature at which a large amount of water vapor condenses (about 58 c for natural gas), after which water is produced because of the condensation of a large amount of water vapor, diluting the acid to a non-corrosive concentration (PH greater than 4). Sulfuric acid can severely corrode stainless steel at a certain concentration and temperature. In the area where the sulfuric acid condensation initially appears, because the sulfuric acid concentration is highest, the temperature is high, the corrosion is the most serious, the plate heat exchanger and the tube-fin heat exchanger can be perforated and failed, and the service life of the heat exchange equipment is seriously shortened.
Even if the fuel is completely desulfurized, the corrosion of sulfuric acid dew point is avoided. However, at the high temperatures of combustion, oxygen and nitrogen can produce nitrogen oxides, some of which are nitrogen dioxide. The nitrogen dioxide can generate nitric acid when meeting water. Therefore, nitric oxide and water vapor in the flue gas can generate nitric acid condensation. The corrosion caused by nitric acid condensation is called nitric acid dew point corrosion. The temperature at which nitrogen oxides in flue gases of civil or industrial gas cause dew point corrosion is generally around 70 ℃ and the corrosion zone continues up to the temperature at which a large amount of water vapour condenses (about 58 ℃ for natural gas), after which the acid is diluted to a non-corrosive concentration (PH greater than 4) because of the large amount of water vapour condensed. Since nitric acid can severely corrode metal materials such as copper, copper ions can promote corrosion of stainless steel. Nitric acid condensation is a serious hazard to brazed stainless steel plate heat exchangers.
Since the temperature of sulfuric acid dew point corrosion is high, the temperature of exhaust gas is generally required to be increased to 180 ℃ or even higher to avoid the dew point corrosion, which wastes a large amount of energy. The dew point corrosion of nitric acid is low, about 70 ℃, and the temperature of the exhausted smoke is usually higher than the temperature, which is not considered to be important. However, if the water vapor in the flue gas needs to be condensed into liquid water so as to release more heat (more than 10% of the natural gas can be recovered), the temperature of the flue gas needs to be reduced to about 30 ℃, and the utilization of low-grade energy of the flue gas is influenced by the dew point corrosion of nitric acid.
Although a direct contact mode of directly spraying the flue gas with water can be adopted, the low-temperature waste heat in the flue gas is recovered, and the heat exchanger made of corrosion-resistant materials such as stainless steel and the like is generally not corroded. However, the water absorbs smoke dust, oxysulfide and nitrogen oxide in the flue gas, so that the water quality is changed, and the water cannot be directly used as domestic hot water. And the water contains a trace amount of acidic substances, and can slowly corrode equipment utilizing the hot water, such as: heating pipelines and radiating fins, evaporator heat exchange tubes of heat pumps and the like.
SUMMERY OF THE UTILITY MODEL
The utility model aims to overcome the defects in the prior art and provide the low-temperature flue gas heat exchanger component which is simple in structure, high in energy utilization rate and stable in heat exchange efficiency and resists dew point corrosion.
The technical scheme of the utility model is as follows: a dew point corrosion resistant low-temperature flue gas heat exchanger assembly comprises a heat exchanger body and a condensed water collecting pool, wherein a flue gas inlet channel is arranged at one end of the heat exchanger body, a flue gas inlet is formed in the flue gas inlet channel, and a spraying device is arranged in the flue gas inlet channel; the other end of the heat exchanger body is provided with a smoke outlet channel; and a water outlet of the condensed water collecting tank is connected with a spraying device through a condensed water circulating pipe.
Furthermore, a condensed water overflow port is arranged at the preset height of the condensed water collecting tank, and a sewage discharge port is arranged at the bottom of the condensed water collecting tank; and a water outlet of the condensation water collecting tank is connected with a condensation water circulating pipe, and the condensation water circulating pipe is connected with a spraying device through a circulating pump.
Furthermore, the condensed water collecting tank is arranged in the flue gas outlet channel, and a flue gas outlet is formed in the rear side of the condensed water collecting tank.
Furthermore, a water collecting tray is arranged below the spraying device, and an outlet of the water collecting tray is connected with a condensed water collecting tank through a water return pipe.
Furthermore, a cold water inlet, a hot water outlet and a condensed water outlet are formed in the heat exchanger body, and the condensed water outlet is communicated with the condensed water collecting tank.
Further, the spraying device comprises a spraying pipe, at least one nozzle is arranged on the spraying pipe, and the condensed water circulating pipe is communicated with the spraying pipe.
Furthermore, the heat exchanger body, the condensed water collecting tank and the spraying device are all made of stainless steel.
Furthermore, the circulating pump is made of stainless steel or high-molecular acid-resistant materials.
Further, the heat exchanger body is a plate type or tube fin type heat exchanger.
Furthermore, the smoke outlet channel is internally provided with a water retaining component.
Further, the heat exchanger body, the flue gas inlet channel and the flue gas outlet channel are integrally formed or separately connected.
Furthermore, the heat exchanger body is connected with the flue gas inlet channel and the flue gas outlet channel by welding, flange connection or high-temperature sealant gluing and pressing.
The utility model has the beneficial effects that: on one hand, flue gas-condensed water circulation can be utilized, so that flue gas with higher temperature can be partially vaporized through a spraying device, the temperature of the flue gas is rapidly reduced, the remaining water mist can absorb sulfur trioxide, sulfur dioxide and nitrogen oxide in the flue gas to form very thin acid liquid, and the PH value of the acid liquid is about 4 under the normal condition, so that the concentration and the temperature of the acid can be greatly reduced, and the corrosion of two dew points of sulfuric acid and nitric acid generated by the flue gas is avoided; on the other hand, the heat of flue gas can make full use of, improves the energy utilization rate of flue gas, but also can wash heat exchanger body deposition in succession through the condensate water that forms behind the flue gas heat transfer, ensures that heat exchange efficiency is stable.
Drawings
FIG. 1 is a schematic structural view of embodiment 1 of the present invention;
fig. 2 is a schematic structural diagram of embodiment 2 of the present invention.
The attached drawings indicate the following:
1. a heat exchanger body; 2. a flue gas inlet channel; 3. a shower pipe; 4. a flue gas outlet channel; 5. a condensed water collection tank; 6. a condensed water circulating pipe; 7. a circulation pump; 8. a water collection tray; 9. a water return pipe; 10. connecting an interface; 11. a cold water inlet; 12. a hot water outlet; 21. a flue gas inlet; 41. a flue gas outlet; 42. a water retaining assembly; 51. a condensed water overflow port; 52. a sewage draining outlet.
Detailed Description
The utility model will be described in further detail below with reference to the drawings and specific examples.
Example 1
As shown in fig. 1: a dew point corrosion resistant low-temperature flue gas heat exchanger assembly comprises a heat exchanger body 1, wherein one end of the heat exchanger body 1 is provided with a flue gas inlet channel 2, a flue gas inlet 21 is arranged on the flue gas inlet channel 2, and a spray pipe 3 is arranged in the flue gas inlet channel 2; the other end of the heat exchanger body 1 is provided with a flue gas outlet channel 4, a condensed water collecting tank 5 is arranged in the flue gas outlet channel, and a flue gas outlet 41 is arranged on the rear side of the condensed water collecting tank 5.
The scheme has the following advantages: by utilizing the circulation of the flue gas and the condensed water, the flue gas with higher temperature can be partially vaporized by the spraying device, the temperature of the flue gas is rapidly reduced, the residual water mist can absorb sulfur trioxide, sulfur dioxide and nitrogen oxide therein to form very thin acid liquid, and the PH value is about 4 under the common condition, so that the concentration and the temperature of the acid can be greatly reduced, and the corrosion of two dew points of sulfuric acid and nitric acid generated by the flue gas is avoided. The unvaporized flue gas enters the heat exchanger body to exchange heat with cold water, so that the heat of the flue gas is fully utilized, and the energy utilization rate of the flue gas is improved. In addition, this embodiment is equipped with the exhanst gas outlet passageway with the condensate collecting pit, and spray set locates flue gas inlet passageway, can improve the compact structure nature of flue gas heat exchanger subassembly, reduces area.
Moreover, although the temperature of the flue gas can be reduced by spraying water mist in the hot flue gas, the preheating grade of the flue gas is reduced, the temperature difference of water in the heat exchanger body is also reduced, and the temperature of hot water discharged from the heat exchanger body can be influenced. However, the flue gas rich in saturated water vapor is rapidly condensed in the heat exchanger body when meeting cold, and the heat exchange coefficient of the water vapor condensation is far higher than that of the forced convection heat exchange of the flue gas. Therefore, the overall heat exchange capacity is rather enhanced, and the hot water temperature is not lowered. A large amount of water vapor condensate is equivalent to slightly acidic softened water, and can continuously wash the accumulated dust of the heat exchanger body, thereby ensuring the stability of heat exchange efficiency.
In this embodiment, a condensate overflow port 51 is provided at a predetermined height of the condensate collecting tank 5, and a drain outlet 52 is provided at the bottom thereof; the water outlet of the condensation water collecting pool 5 is connected with a condensation water circulating pipe 6, the condensation water circulating pipe 6 is connected with the spray pipe 3 through a circulating pump 7, and a plurality of nozzles are arranged on the spray pipe 3. Tap water can be put into the condensation water collecting pool 5 for circulation at the beginning of system operation or after cleaning and pollution discharge, and after operation, the flue gas generates enough condensation water to maintain the water level. Because the flue gas can constantly produce water, through setting up condensate overflow mouth 5, when the condensate in the condensate collecting tank was higher than the condensate overflow mouth, discharge in the condensate overflow mouth can be followed to unnecessary condensate to prevent that the condensate in the condensate collecting tank from storing up the overfilling. When the amount of water in the condensate collection sump is small and not required for use, the remaining condensate can be discharged through the drain outlet 52. When the water quantity is small, the water can be directly discharged, and can also be collected and utilized (such as water supplement of a cooling tower, flushing of a toilet and the like), and when the water quantity is large, alkali can be added to adjust the pH value, and then the water is discharged.
In this embodiment, a water collecting tray 8 is arranged below the spray pipe 3, and an outlet of the water collecting tray 8 is connected with the condensed water collecting tank 5 through a water return pipe 9. The circulation of the condensed water needs to maintain a larger flow rate so as to ensure that more water mist exists after the water is preheated and vaporized; through setting up water-collecting tray 8 and depositing water and set up 9 backwaters of wet return, can make these deposit water and play the water seal effect, avoid the flue gas to walk around heat exchanger body 1.
In this embodiment, the upper portion of the heat exchanger body 1 is provided with a cold water inlet 11 and a hot water outlet 12, and the lower portion is provided with a condensed water outlet, which is communicated with the condensed water collecting tank 5. When cold water is introduced into the heat exchanger body 1, the cold water exchanges heat with high-temperature flue gas, the cold water is heated to become hot water and is output from a hot water outlet 12, and after the high-temperature flue gas is cooled, a part of the hot water is changed into low-temperature flue gas and is output from a flue gas outlet channel; and the other part of the condensed water forms condensed water and enters a condensed water collecting pool. As the fuel burns, the hydrogen element in the fuel can generate a large amount of water vapor, for example, 16kg of methane can generate 36kg of water when the methane is completely burnt, and when the temperature of the flue gas is reduced to be below 58 ℃, a large amount of condensed water can be generated in the flue gas. Therefore, one part of the cooled flue gas generates condensed water, and the other part of the cooled flue gas forms low-temperature flue gas.
In this embodiment, the flue gas inlet, the water collecting tray, the condensed water collecting tank, the condensed water overflow port, the drain, the condensed water circulating pipe, and the return pipe are all in a relatively high temperature, humidity, and slightly acidic environment, and therefore, the flue gas inlet, the water collecting tray, the condensed water collecting tank, the condensed water overflow port, the drain, the condensed water circulating pipe, and the return pipe are preferably made of stainless steel materials. The spray pipe is also preferably made of stainless steel and has better atomization performance. The circulating pump can adopt a stainless steel acid-proof pump or a high polymer material acid-proof pump.
In this embodiment, the heat exchanger body is a plate-type or tube-fin heat exchanger, and preferably made of stainless steel. The plate heat exchanger may be a welded or a removable plate heat exchanger. The welded plate heat exchanger may be brazed with copper, stainless steel or nickel; non-brazing welding such as resistance welding and laser welding may be used. The heat exchange tubes and the fins of the tube-fin heat exchanger can be welded or pressed. In this embodiment, the heat exchanger body, the flue gas inlet channel 2 and the flue gas outlet channel 4 are of a brand new design structure, thereby forming a brand new flue gas heat exchanger component.
The working principle of the embodiment is as follows: high-temperature flue gas enters the flue gas inlet channel 2 through the flue gas inlet 21 and is sprayed by the spraying pipe 3 in the flue gas inlet channel, so that the flue gas is partially vaporized after being sprayed, the temperature of the flue gas is reduced, the remaining water mist can absorb sulfur trioxide, sulfur dioxide and nitrogen oxide in the flue gas to form very thin acid liquid, and the PH is about 4 under the normal condition, so that the concentration and the temperature of the acid can be greatly reduced, and the corrosion of two dew points of sulfuric acid and nitric acid generated by the flue gas is avoided; the vaporized flue gas becomes condensed water and falls into the water collecting tray 8; the unvaporized flue gas enters the heat exchanger body 1 to exchange heat with cold water in the heat exchanger body 1, the cold water is heated to become hot water and is output from the hot water outlet 12, after the flue gas is cooled, one part of the hot water forms condensed water and enters the condensed water collecting tank 5, and the other part of the hot water forms low-temperature flue gas and is output from the flue gas outlet channel 4. Wherein, the condensed water collecting pool 5 conveys the condensed water for the spraying pipe 3 through the condensed water circulating pipe 6 and the circulating pump 7, and the water stored in the water collecting tray 8 is conveyed to the condensed water collecting pool 5 through the water return pipe 9, thereby forming the recycling of the condensed water.
Example 2
As shown in fig. 2: the difference from embodiment 1 is that the heat exchanger body 1 is a plate heat exchanger or a tube and fin heat exchanger already in use and is not a new product. To this kind of heat exchanger body 1 in the use, because its material does not necessarily adopt the stainless steel, also does not set up spray set and condensate collecting pit, in order to reduce the flue gas to its corruption, this embodiment sets up flue gas inlet channel 2 and flue gas outlet passageway 4 respectively at the both ends of heat exchanger body, the one end of flue gas inlet channel 2 and flue gas outlet passageway 4 sets up the connection interface 10 that links to each other with original flue respectively promptly, the other end is connected with heat exchanger body 1, the connected mode can be welding, flange joint, the gluey and compress tightly of high temperature sealed glue and connect.
In addition, the flue gas outlet channel 4 is internally provided with a water retaining component 42, the water retaining component 42 is arranged above the condensed water collecting tank 5, and the water retaining component 42 is used for blocking water drops rushed out of the heat exchanger body 1 along with the air flow and enabling the water drops to be gathered and enter the condensed water collecting tank 5. Since the water stop assembly 42 is in a relatively high humidity and slightly acidic environment, stainless steel is preferred.
Claims (10)
1. A dew point corrosion resistant low-temperature flue gas heat exchanger component is characterized by comprising a heat exchanger body and a condensed water collecting pool, wherein one end of the heat exchanger body is provided with a flue gas inlet channel, the flue gas inlet channel is provided with a flue gas inlet, and a spraying device is arranged in the flue gas inlet channel; the other end of the heat exchanger body is provided with a smoke outlet channel; and a water outlet of the condensed water collecting tank is connected with a spraying device through a condensed water circulating pipe.
2. The dew point corrosion resistant cryogenic flue gas heat exchanger assembly of claim 1 wherein the condensate collection sump has a condensate overflow at a predetermined height and a drain at a bottom; and a water outlet of the condensation water collecting tank is connected with a condensation water circulating pipe, and the condensation water circulating pipe is connected with a spraying device through a circulating pump.
3. A dew point corrosion resistant cryogenic flue gas heat exchanger assembly according to claim 1 or 2 wherein the condensate collection sump is located within the flue gas outlet channel, the rear side of the condensate collection sump being provided with a flue gas outlet.
4. The dew point corrosion resistant low temperature flue gas heat exchanger assembly of claim 1 or 2 wherein a water collection tray is provided below the spray means, and an outlet of the water collection tray is connected to the condensate collection tank via a return pipe.
5. The dew point corrosion resistant cryogenic flue gas heat exchanger assembly of claim 1 or 2 wherein the heat exchanger body is provided with a cold water inlet, a hot water outlet and a condensate outlet, the condensate outlet being in communication with a condensate collection sump.
6. The dew point corrosion resistant cryogenic flue gas heat exchanger assembly of claim 2 wherein the spray means comprises a spray pipe having at least one spray nozzle thereon, the condensate circulating tube being in communication with the spray pipe.
7. The dew point corrosion resistant low temperature flue gas heat exchanger assembly of claim 1 or 2 wherein the heat exchanger body, the condensate collection sump, and the spray system are all stainless steel.
8. A low temperature flue gas heat exchanger assembly against dew point corrosion according to claim 1 or 2 wherein said flue gas outlet channel is internally provided with a water retaining assembly.
9. A dew point corrosion resistant cryogenic flue gas heat exchanger assembly according to claim 1 or 2 wherein the heat exchanger body, flue gas inlet channel and flue gas outlet channel are integrally formed or separately connected.
10. The dew point corrosion resistant cryogenic flue gas heat exchanger assembly of claim 9 wherein the heat exchanger body is bonded and compression bonded to the flue gas inlet channel and the flue gas outlet channel by welding, flange bonding or high temperature sealant.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122050206.3U CN215637275U (en) | 2021-08-30 | 2021-08-30 | Dew point corrosion resistant low-temperature flue gas heat exchanger assembly |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122050206.3U CN215637275U (en) | 2021-08-30 | 2021-08-30 | Dew point corrosion resistant low-temperature flue gas heat exchanger assembly |
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| CN215637275U true CN215637275U (en) | 2022-01-25 |
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|---|---|---|---|
| CN202122050206.3U Active CN215637275U (en) | 2021-08-30 | 2021-08-30 | Dew point corrosion resistant low-temperature flue gas heat exchanger assembly |
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2021
- 2021-08-30 CN CN202122050206.3U patent/CN215637275U/en active Active
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