Split type phase change heat exchanger capable of preventing low-temperature dew point corrosion
By using a counter-current and co-current combination connection between the flue gas heat exchange tube bundle and the first heat exchange tube bundle in a split phase change heat exchanger, the co-current heat transfer of cold and hot fluids is achieved, which solves the problem of low-temperature dew point corrosion, increases the tube bundle wall temperature in the low-temperature region of the heat exchanger, and reduces the risk of equipment corrosion.
Patent Information
- Application Number
- CN202422820141.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2026-01-20
- Estimated Expiration
- 2034-11-19
AI Technical Summary
Split-type phase change heat exchangers are at risk of low-temperature dew point corrosion in low-temperature regions, and existing technologies are insufficient to effectively increase the wall temperature of the heat exchange tubes to reduce this risk.
The flue gas heat exchange tube bundle is connected to the first heat exchange tube bundle in a counter-current and co-current combination. Heat is transferred through the co-current flow of cold and hot fluids, which reduces the heat exchange temperature difference and increases the tube bundle wall temperature.
It effectively avoids low-temperature dew point corrosion, increases the wall temperature of the tube bundle in the low-temperature zone of the heat exchanger, and reduces the risk of equipment corrosion.
Smart Images
Figure CN223815011U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of waste heat recovery, in particular to a split type phase-change heat exchanger capable of preventing low-temperature dew point corrosion. BACKGROUND
[0002] The split type phase-change heat exchanger is a high-efficiency heat exchange equipment, which has a series of advantages such as extremely high thermal conductivity, good isothermality, long-distance heat transfer, and controllable temperature, through phase-change heat transfer of a working medium. The heat exchanger is composed of an evaporation section and a condensation section of the circulating working medium, and the circulating working medium is arranged in the heat exchange tube bundle. The evaporation section and the condensation section are separated from each other, and are connected into a circulating loop through a steam rising pipe and a condensate return pipe.
[0003] In the engineering application of the split type phase-change heat exchanger, the evaporation section tube bundle is arranged in a hot fluid passage, i.e. a hot fluid heat exchanger. The evaporation section tube bundle absorbs heat of the hot fluid, and the heat is transferred to the circulating medium in the tube bundle through the heat absorption tube bundle. The circulating medium absorbs heat and changes from a liquid phase to a vapor phase, and is transmitted to the condensation section through the steam rising pipe. The condensation section tube bundle is arranged in a cold fluid passage, i.e. a cold fluid heat exchanger. The vapor phase circulating medium transfers heat to the cold fluid through the heat release tube bundle, so as to be condensed and changed into a liquid phase. Then, the liquid phase is returned to the evaporation section through the condensate return pipe, and the cycle is repeated. Through the high-efficiency split type phase-change heat transfer, the purpose of heat exchange between the cold fluid and the hot fluid is achieved.
[0004] In the steel industry, the split type phase-change heat exchanger is widely used in the fields of heating blast furnace gas (hereinafter referred to as gas) or heating air by flue gas, due to its characteristics and advantages.
[0005] Taking the heating of gas by flue gas as an example, in actual engineering application, in order to ensure that there is a larger heat exchange temperature difference between the flue gas side and the gas side, the traditional gas heater usually adopts the type of counter-flow heat exchange between the flue gas and the gas, so as to increase the heat exchange capacity of the equipment and reduce the manufacturing cost of the equipment. Counter-flow means that the flow directions of the flue gas and the gas are opposite when they flow through the tube bundle for heat exchange; and co-flow means that the flow directions of the flue gas and the gas are the same when they flow through the tube bundle for heat exchange. When the counter-flow heat exchange is adopted, the wall temperature of the heat exchange tube decreases from the flue gas inlet to the flue gas outlet. In this way, the wall temperature of the flue gas outlet tube bundle / gas inlet tube bundle is the lowest. When the wall surface temperature of the heat exchange tube is lower than the dew point temperature of the flue gas / gas, the heat exchange tube is at risk of being corroded.
[0006] Therefore, it is necessary to take measures to increase the wall temperature of the heat exchange tube in the low-temperature area of the flue gas / first heat exchange shell, so as to reduce the corrosion risk of the equipment. For the phase-change heat exchanger, although the heat flux density of the heat exchange tube can be adjusted by adjusting the structure size of the fin on the surface of the heat exchange tube, and then the wall surface temperature of the heat exchange tube is affected, the influence of such adjustment on the wall surface temperature of the heat exchange tube is limited.
[0007] Therefore, it is necessary to seek a scheme for effectively improving the wall surface temperature of the heat exchange pipe in the low-temperature region of the equipment and reducing the risk of low-temperature dew point corrosion of the equipment. Utility model content
[0008] The application provides a split type phase change heat exchanger capable of preventing low-temperature dew point corrosion.
[0009] The application provides a split type phase change heat exchanger capable of preventing low-temperature dew point corrosion.
[0010] The flue gas heat exchanger comprises a flue gas heat exchange shell and a plurality of flue gas heat exchange tube bundles; the flue gas heat exchange tube bundles are arranged inside the flue gas heat exchange shell.
[0011] The first heat exchanger comprises a first heat exchange shell and a plurality of first heat exchange tube bundles; the first heat exchange tube bundles are arranged inside the first heat exchange shell.
[0012] The flue gas heat exchange tube bundles and the first heat exchange tube bundles are connected through steam rising pipes and condensed water descending pipes; each flue gas heat exchange tube bundle is connected to one first heat exchange tube bundle.
[0013] The flue gas heat exchange tube bundles and the first heat exchange tube bundles are connected in the reverse and forward flow combination mode.
[0014] Further, the flue gas flow through the flue gas heat exchange tube bundles and the first gas flow through the first heat exchange tube bundles are opposite.
[0015] For n flue gas heat exchange tube bundles and n first heat exchange tube bundles, the serial numbers of the flue gas heat exchange tube bundles are A1, A2, A3, A4,..., An-2, An along the flow direction of the flue gas; the serial numbers of the first heat exchange tube bundles are B1, B2, B3,..., Bn-1, Bn.
[0016] The number of the tube bundles in the forward flow combination mode is set as m; m is less than n; the forward flow tube bundles are arranged behind the reverse flow tube bundles along the flue gas direction.
[0017] The flue gas heat exchange tube bundles and the first heat exchange tube bundles are connected through steam rising pipes and condensed water descending pipes, comprising:
[0018] Along the flow direction of the flue gas, for the first n-m tube bundles, the flue gas heat exchange tube bundle A1 is connected to the first heat exchange tube bundle B1, the flue gas heat exchange tube bundle A2 is connected to the first heat exchange tube bundle B2, and the connection is sequentially performed according to the serial numbers of the tube bundles until the reverse flow connection of the flue gas heat exchange tube bundle An-m to the first heat exchange tube bundle Bn-m.
[0019] For the last m tube bundles, the flue gas heat exchange tube bundle An-m+1 is connected to the first heat exchange tube bundle Bn, the flue gas heat exchange tube bundle An-m+2 is connected to the first heat exchange tube bundle Bn-1, and so on until An is connected to Bn-m+1 in parallel flow.
[0020] Further, the number m of the tube bundles in parallel flow combination is determined according to actual requirements.
[0021] Further, the gas in the first heat exchanger is coal gas or air.
[0022] The present application adopts the parallel flow heat transfer mode of cold and hot fluids in the low-temperature area of the flue gas heat exchanger and the first heat exchanger, reduces the heat transfer temperature difference, increases the tube bundle wall temperature, and prevents the tube bundle from being affected by dew point corrosion. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 A top view schematic diagram of a flue gas-coal gas split type phase change heat exchanger tube bundle counter flow heat transfer arrangement is provided in the present application.
[0024] Figure 2 A heat exchanger heat exchange tube bundle working medium circulation loop schematic diagram is provided in the split type phase change heat exchanger of the present application.
[0025] Figure 3 A top view of the heat exchanger tube bundle heat transfer counter flow and parallel flow combination type provided in the present application.
[0026] The reference signs are: 100, flue gas heat exchanger; 101, flue gas heat exchange shell; 102, flue gas heat exchange tube bundle; 200, first heat exchanger; 201, first heat exchange shell; 202, first heat exchange tube bundle; 300, steam rising pipe; 400, condensate water descending pipe. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical scheme and advantages of the present application clearer, the following will further describe the embodiments of the present application in combination with the drawings.
[0028] In order to facilitate the description, the flue gas-coal gas split type phase change heat exchanger is taken as an example to specifically describe the present application.
[0029] As shown in Figure 1 and Figure 2 , the flue gas-coal gas split type phase change heat exchanger comprises a flue gas heat exchanger 100 and a first heat exchanger 200. The flue gas heat exchanger 100 comprises a flue gas heat exchange shell 101 and a plurality of flue gas heat exchange tube bundles 102; the first heat exchanger 200 comprises a first heat exchange shell 201 and a plurality of first heat exchange tube bundles 202. The flue gas heat exchange tube bundle 102 and the first heat exchange tube bundle 202 are connected through the steam rising pipe 300 and the condensate water descending pipe 400 in correspondence, and form a circulation loop of the heat transfer working medium in the tube bundle.
[0030] In order to ensure that the flue gas side and the coal gas side have a larger heat exchange temperature difference, the flue gas and the coal gas are usually in countercurrent heat exchange type Figure 1 , the flue gas flow direction is opposite to the coal gas flow direction, the flue gas heat exchange tube bundle 102 and the first heat exchange tube bundle 202 are connected one by one through the steam rising pipe 300 and the condensate water descending pipe 400, and the corresponding connection relationship is as follows: A1-B1, A2-B2, A3-B3, A4-B4, …, A(n-2)-B(n-2), A(n-1)-B(n-1), A(n)-B(n). At this time, the heat exchange tube wall temperature decreases from the flue gas inlet to the outlet, so that the flue gas outlet tube bundle / coal gas inlet tube bundle wall temperature is the lowest (for example: ~ 80℃), at this time, the low temperature area tube bundle heat exchange tube of the equipment has the risk of wall temperature being less than the dew point temperature of the flue gas / coal gas and the heat exchange tube being corroded.
[0031] see Figure 3 In order to solve the above problems, the heat exchange mode of the tube bundle counterflow and flow combination arrangement is provided, which effectively improves the tube bundle wall temperature of the low temperature part of the heat exchanger and avoids the low temperature dew point corrosion of the equipment.
[0032] The specific implementation is as follows: in order to ensure that the flue gas side and the coal gas side have a larger heat exchange temperature difference and ensure that the equipment has a higher heat exchange effect, the corresponding relationship between the flue gas heat exchange tube bundle 102 and the first heat exchange tube bundle 202 is still set in the countercurrent mode of cold and hot fluids. The equipment realizes maximum heat transfer through a larger heat exchange temperature difference and a set heat exchange area.
[0033] Through heat transfer calculation, the number of heat exchange tube rows with low tube bundle wall temperature, close to or lower than the dew point temperature of the flue gas / coal gas and the risk of corrosion, that is, the value of m is 4 rows, for the last 4 rows of heat exchange tube bundles, the countercurrent heat transfer mode of cold and hot fluids is adopted to reduce the heat exchange temperature difference, improve the tube bundle wall temperature (higher than the dew point temperature of the flue gas / coal gas) and make it not affected by the dew point corrosion.
[0034] At this time, the corresponding connection relationship between the flue gas heat exchange tube bundle 102 and the first heat exchange tube bundle 202 through the steam rising pipe 300 and the condensate water descending pipe 400 is not single countercurrent or flow, but is in the form of countercurrent and flow combination, and the corresponding connection relationship is as follows: A1-B1, A2-B2, A3-B3, A4-B4, …, A(n-3)-B(n), A(n-2)-B(n-1), A(n-1)-B(n-2), A(n)-B(n-3). At this time, the 4 rows of tube bundles in the low temperature area realize flow heat transfer, the wall temperature rises to be higher than the dew point temperature of the flue gas / coal gas, and the heat exchange tube avoids the risk of corrosion.
[0035] The above embodiment is only described for the smoke-gas split type phase change heat exchanger, and for the smoke-air split type phase change heat exchanger, the same technical scheme is implemented according to the above embodiment, and the technical scheme falls within the protection scope of the utility model.
[0036] The above-described embodiments of the present application do not constitute a limitation on the protection scope of the present application.
Claims
1. A split type phase change heat exchanger for preventing low temperature dew point corrosion, characterized by, The split phase-change heat exchanger comprises a flue gas heat exchanger (100) and a first heat exchanger (200); The flue gas heat exchanger (100) comprises a flue gas heat exchange shell (101) and a plurality of flue gas heat exchange tube bundles (102); the flue gas heat exchange tube bundles (102) are arranged inside the flue gas heat exchange shell (101); The first heat exchanger (200) comprises a first heat exchange shell (201) and a plurality of first heat exchange tube bundles (202); the first heat exchange tube bundles (202) are arranged inside the first heat exchange shell (201); The flue gas heat exchange tube bundles (102) and the first heat exchange tube bundles (202) are connected through steam rising pipes (300) and condensate water descending pipes (400); each flue gas heat exchange tube bundle is connected with one first heat exchange tube bundle; The flue gas heat exchange tube bundles and the first heat exchange tube bundles are connected in the reverse and forward flow combination mode.
2. The split phase change heat exchanger of claim 1, wherein, The flue gas flows through the flue gas heat exchange tube bundles (102), and the first gas flows through the first heat exchange tube bundles (202) in the opposite direction; For n flue gas heat exchange tube bundles and n first heat exchange tube bundles, the serial numbers of the flue gas heat exchange tube bundles are A1, A2, A3, A4, …, An-2, An-1, An in the direction of the flue gas flow; the serial numbers of the first heat exchange tube bundles are B1, B2, B3, …, Bn-1, Bn; The number of the tube bundles in the forward flow combination mode is set as m; m is less than n; the forward flow tube bundles are arranged behind the reverse flow tube bundles in the direction of the flue gas flow; The flue gas heat exchange tube bundles (102) and the first heat exchange tube bundles (202) are connected through the steam rising pipes (300) and the condensate water descending pipes (400), comprising: In the direction of the flue gas flow, for the first n-m tube bundles, the flue gas heat exchange tube bundle A1 is connected with the first heat exchange tube bundle B1, the flue gas heat exchange tube bundle A2 is connected with the first heat exchange tube bundle B2, and the connection is sequentially performed according to the serial numbers until the reverse connection of the flue gas heat exchange tube bundle An-m to the first heat exchange tube bundle Bn-m; For the last m tube bundles, the flue gas heat exchange tube bundle An-m+1 is connected with the first heat exchange tube bundle Bn, the flue gas heat exchange tube bundle An-m+2 is connected with the first heat exchange tube bundle Bn-1, and the connection is sequentially performed until the forward connection of the flue gas heat exchange tube bundle An to the first heat exchange tube bundle Bn-m+1.
3. The split phase change heat exchanger of claim 1, wherein, The gas in the first heat exchanger (200) is coal gas or air.