Tail gas waste heat recovery method and tail gas waste heat recovery system

Abstract

The invention relates to the technical field of waste heat recovery, in particular to a tail gas waste heat recovery method and a tail gas waste heat recovery system. The tail gas waste heat recovery method comprises the following steps that a water-containing material enters a drying furnace, the dried material is discharged out of the drying furnace, and tail gas generated during drying is collected; the tail gas enters the heat exchange device to exchange heat with a first heat exchange medium, the first heat exchange medium supplies heat after exchanging heat, the first heat exchange medium enters the heat exchange device to continuously exchange heat after completing heat supply, the tail gas exchanges heat with the first heat exchange medium to supply heat, and the tail gas after completing heat supply enters the pre-drying device to pre-dry a water-containing material; or the tail gas after heat exchange directly enters the pre-drying device to pre-dry the water-containing material. The first heat exchange medium after heat exchange and the tail gas after heat exchange supply heat together, and the tail gas after heat exchange can predry the water-containing material, so that the utilization rate of energy is effectively improved, and meanwhile, the energy consumption of the drying furnace is also reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery, and in particular to a tail gas waste heat recovery method and a tail gas waste heat recovery system. Background Art

[0002] Because fluorite powder is fine and has high value, wet powder is usually used for transportation to reduce losses during transportation. Therefore, before processing the fluorite powder, the fluorite powder needs to be dried first. When drying the fluorite powder, a large amount of high-temperature exhaust gas will be generated. The high-temperature exhaust gas is usually discharged after being purified to the standard for external discharge. This will cause a large amount of heat energy to be discharged, and the energy cannot be effectively utilized. Summary of the invention

[0003] In view of this, the present invention provides a tail gas waste heat recovery method and a tail gas waste heat recovery system to solve the problem that a large amount of heat energy is discharged and the energy cannot be effectively utilized.

[0004] In a first aspect, the present invention provides a method for recovering waste heat from tail gas, comprising the following steps:

[0005] The water-containing material enters the drying furnace, and the dried material is discharged from the drying furnace, and the tail gas generated during drying is collected;

[0006] The tail gas enters the heat exchange device to exchange heat with the first heat exchange medium, and the first heat exchange medium provides heat after heat exchange. After the first heat exchange medium completes heat supply, it enters the heat exchange device to continue heat exchange, and the tail gas exchanges heat with the first heat exchange medium to provide heat. After the heat supply is completed, the tail gas enters the pre-drying device to pre-dry the water-containing material, or the tail gas after heat exchange directly enters the pre-drying device to pre-dry the water-containing material.

[0007] In an optional embodiment, the first heat exchange medium and the second heat exchange medium exchange heat in a heat exchanger after heat exchange, the second heat exchange medium after heat exchange provides heat, and the second heat exchange medium after heat supply returns to the heat exchanger to continue heat exchange;

[0008] The first heat exchange medium after heat exchange in the heat exchanger returns to the heat exchange device to exchange heat with the tail gas.

[0009] In an optional embodiment, dust and odor in the exhaust gas can be removed while the exhaust gas enters the heat exchange device for heat exchange.

[0010] In an optional embodiment, when the first heat exchange medium exchanges heat with the exhaust gas, the first heat exchange medium removes dust and odor in the exhaust gas.

[0011] In an optional embodiment, the first heat exchange medium enters a sedimentation tank after heat supply is completed to precipitate the impurities carried, and the first heat exchange medium after precipitation enters a heat exchange device to exchange heat with the tail gas.

[0012] In an optional embodiment, the exhaust gas that has completed pre-drying enters an exhaust device for discharge, and the water-containing material that has completed pre-drying enters a drying furnace for drying.

[0013] In a second aspect, the present invention further provides a tail gas waste heat recovery system, which is applied to the tail gas waste heat recovery method described in any of the above schemes, comprising:

[0014] Drying furnace;

[0015] A heat exchange device, the heat exchange device is connected to the drying furnace through a pipeline, and the tail gas in the drying furnace is suitable for entering the heat exchange device through the pipeline;

[0016] A first heat supply pipeline, both ends of which are respectively connected to the heat exchange device, a first heat exchange medium is contained in the first heat supply pipeline, and the first heat supply pipeline passes through the portion to be heated;

[0017] a second heat supply pipeline, one end of which is connected to the heat exchange device, the second heat supply pipeline passes through the portion to be heated, and the exhaust gas is suitable for being heated by the second heat supply pipeline;

[0018] A pre-drying device, wherein the pre-drying device is connected to the drying furnace through a material transportation device, the pre-drying device is connected to the other end of the second heating pipeline, or is connected to the heat exchange device through a pre-drying pipeline, and the exhaust gas is suitable for entering the pre-drying device through the second heating pipeline or entering the pre-drying device through the pre-drying pipeline.

[0019] In an optional implementation, it also includes:

[0020] Heat exchangers;

[0021] A third heating pipeline, the third heating pipeline and the first heating pipeline are suitable for heat exchange through the heat exchanger, the third heating pipeline has a second heat exchange medium, and the third heating pipeline passes through the part to be heated.

[0022] In an optional implementation, it also includes:

[0023] A sedimentation tank, wherein the first heat supply pipeline is connected to the sedimentation tank, and the sedimentation tank is connected to the heat exchange device through a pipeline.

[0024] In an optional implementation, it also includes:

[0025] A sewage treatment device is connected to the sedimentation tank.

[0026] Beneficial effects:

[0027] The present invention provides a method for recovering waste heat from exhaust gas, wherein a first heat exchange medium exchanges heat with the exhaust gas in a heat exchange device, and the first heat exchange medium after heat exchange and the exhaust gas after heat exchange jointly provide heat, and the exhaust gas after heat exchange can also pre-dry the water-containing material, thereby effectively improving the utilization rate of energy and reducing the energy consumption of the drying furnace.

[0028] Because the exhaust gas waste heat recovery system is used in the exhaust gas waste heat recovery method and has the same effect as the exhaust gas waste heat recovery method, it will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 The figure is a schematic flow chart of a method for recovering waste heat from exhaust gas according to an embodiment of the present invention.

[0031] Description of reference numerals:

[0032] 1. Drying furnace; 2. Heat exchange device; 3. Pre-drying device; 4. Heat exchanger; 5. Sedimentation tank; 6. First heating pipeline; 7. Second heating pipeline; 8. Material transportation device; 9. Pre-drying pipeline; 10. Third heating pipeline; 11. Sewage treatment device; 12. Exhaust gas; 13. First heat exchange medium; 14. Part to be heated. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0034] Combine the following Figure 1 , describing an embodiment of the present invention.

[0035] According to an embodiment of the present invention, on the one hand, a method for recovering waste heat from exhaust gas is provided, comprising the following steps:

[0036] The water-containing material enters the drying furnace, and the dried material is discharged from the drying furnace, and the tail gas generated during drying is collected;

[0037] The tail gas enters the heat exchange device to exchange heat with the first heat exchange medium, and the first heat exchange medium provides heat after heat exchange. After the first heat exchange medium completes heat supply, it enters the heat exchange device to continue heat exchange, and the tail gas exchanges heat with the first heat exchange medium to provide heat. After the heat supply is completed, the tail gas enters the pre-drying device to pre-dry the water-containing material, or the tail gas after heat exchange directly enters the pre-drying device to pre-dry the water-containing material.

[0038] In this embodiment, the water-containing material is wet fluorite powder with a water content of 15%. The wet fluorite powder is sent to a drying furnace for drying. After being dried to a water content of less than 0.1%, it is discharged from the drying furnace to proceed to the next production process. In the process of drying the wet fluorite powder, a large amount of exhaust gas will be generated. The exhaust gas is collected and enters the heat exchange device.

[0039] The heat exchange device is a water washing tower, and the first heat exchange medium is water. Water exchanges heat with the exhaust gas in the water washing tower. The temperature of the water after the heat exchange is 60°C, and then the water enters the heating section through a pipeline for heating; the exhaust gas temperature after the heat exchange drops to 80°C, and the exhaust gas after the heat exchange enters the heating section through a pipeline for heating. The exhaust gas after the heat exchange and the water after the heat exchange are heated together, which can better improve the heating effect. After the heating is completed, the exhaust gas will enter the pre-drying device to pre-dry the wet fluorite powder with a water content of 15%; when the exhaust gas is not needed for heating, the exhaust gas after the heat exchange can directly enter the pre-drying device through a pipeline to pre-dry the wet fluorite powder with a water content of 15%.

[0040] Preferably, the first heat exchange medium and the exhaust gas after heat exchange will provide heat to the factory building.

[0041] It should be noted that the first heat exchange medium exchanges heat with the exhaust gas in the heat exchange device, and the first heat exchange medium and the exhaust gas after heat exchange jointly provide heat, and the exhaust gas after heat exchange can also pre-dry the water-containing material, which effectively improves the energy utilization rate and reduces the energy consumption of the drying furnace.

[0042] In some embodiments, the following steps are also included: while the exhaust gas enters the heat exchange device for heat exchange, dust and odor in the exhaust gas can be removed.

[0043] In some embodiments, the following steps are also included: when the first heat exchange medium exchanges heat with the exhaust gas, the first heat exchange medium removes dust and odor in the exhaust gas.

[0044] In this embodiment, the exhaust gas collected from the drying furnace contains oleic acid, dust and water vapor. Oleic acid will cause odor in the exhaust gas. The oleic acid and dust in the exhaust gas need to be removed before the exhaust gas is discharged. The exhaust gas enters from the bottom of the water washing tower, and the wide-angle nozzle in the water washing tower sprays the exhaust gas. The first heat exchange medium is sprayed in the water washing tower through the wide-angle nozzle and exchanges heat with the exhaust gas. At the same time, the oleic acid and dust in the exhaust gas can be taken away to purify the exhaust gas.

[0045] In some embodiments, the following steps are also included: the first heat exchange medium enters a sedimentation tank after the heat supply is completed to precipitate the impurities carried, and the first heat exchange medium after precipitation is completed enters a heat exchange device to exchange heat with the exhaust gas.

[0046] In this embodiment, if Figure 1 As shown, after the heat supply is completed, the first heat exchange medium enters the sedimentation tank and stands still in the sedimentation tank, so that the impurities in the first heat exchange medium are precipitated in the sedimentation tank. After the precipitation is completed, the first heat exchange medium enters the water washing tower again for heat exchange and heat supply.

[0047] In some embodiments, the method further includes the following steps: the first heat exchange medium and the second heat exchange medium exchange heat in a heat exchanger, the second heat exchange medium provides heat after heat exchange, and the second heat exchange medium returns to the heat exchanger to continue heat exchange after heat supply;

[0048] The first heat exchange medium after heat exchange in the heat exchanger returns to the heat exchange device to exchange heat with the tail gas.

[0049] In this embodiment, if Figure 1 As shown, since there are impurities such as oleic acid and dust in the first heat exchange medium, the first heat exchange medium needs to enter the heat exchanger to exchange heat with the second heat exchange medium after flowing out of the water washing tower to avoid the impurities in the first heat exchange medium clogging the heat supply pipeline. The first heat exchange medium and the second heat exchange medium exchange heat in a non-contact manner, and the second heat exchange medium after heat exchange provides heat. After the heat supply is completed, the second heat exchange medium continues to enter the heat exchanger to exchange heat with the first heat exchange medium for circulation.

[0050] Preferably, the second heat exchange medium is soft water.

[0051] In some embodiments, the following steps are also included: the pre-dried tail gas enters the emission device for discharge, and the pre-dried water-containing material enters the drying furnace for drying.

[0052] In this embodiment, if Figure 1 As shown, the exhaust gas that has completed pre-drying will enter the emission device, and the water-containing material that has completed pre-drying will enter the drying furnace for drying, and the emission device is an external exhaust chimney.

[0053] According to an embodiment of the present invention, on the other hand, a tail gas waste heat recovery system is also provided, which is applied to the tail gas waste heat recovery method described in the above embodiment, including: a drying furnace, a heat exchange device, a first heating pipeline, a second heating pipeline and a pre-drying device.

[0054] Specifically, the heat exchange device is connected to the drying furnace through a pipeline, and the exhaust gas in the drying furnace is suitable for entering the heat exchange device through the pipeline. Both ends of the first heat supply pipeline are respectively connected to the heat exchange device, the first heat supply pipeline has a first heat exchange medium, and the first heat supply pipeline passes through the part to be heated. One end of the second heat supply pipeline is connected to the heat exchange device, the second heat supply pipeline passes through the part to be heated, and the exhaust gas is suitable for heating through the second heat supply pipeline. The pre-drying device is connected to the drying furnace through the material transportation device, the pre-drying device is connected to the other end of the second heat supply pipeline, or is connected to the heat exchange device through the pre-drying pipeline, and the exhaust gas is suitable for entering the pre-drying device through the second heat supply pipeline or entering the pre-drying device through the pre-drying pipeline.

[0055] In this embodiment, the material transportation device transports the water-containing material to the drying furnace and dries the material in the drying furnace. The drying furnace is connected to the material storage device, and the dried material can enter the material storage device. The drying furnace is connected to the heat exchange device through a pipeline, and the exhaust gas generated by drying can be transported to the heat exchange device through the pipeline. The heat exchange device is a water washing tower, and the exhaust gas enters the water washing tower from the lower end of the water washing tower. A spray structure is arranged in the water washing tower. One end of the first heat supply pipe is connected to the spray structure, and the other end of the first heat supply pipe is connected to the water collecting tank at the bottom of the water washing tower. The first heat exchange medium in the first heat supply pipe can enter the spray structure, and is sprayed in the water washing tower by the spray structure to exchange heat with the exhaust gas. The first heat exchange medium after heat exchange enters the water collecting tank and enters the first heat supply pipeline through the other end of the first heat supply pipeline. The first heat supply pipeline passes through the part to be heated. When the first heat exchange medium after heat exchange flows in the first heat supply pipeline, it will heat the part to be heated. The water washing tower is connected to the pre-drying device through the second heating pipeline, and the second heating pipeline will pass through the waiting heating part. The tail gas after heat exchange will enter the pre-drying device through the second heating pipeline. The tail gas after heat exchange will pass through the waiting heating part during the flow of the second heating pipeline to provide heat for the waiting heating part. The tail gas after heat exchange finally enters the pre-drying device. The material transportation device can transport the water-containing material to the pre-drying device and pre-dry it through the tail gas after heat exchange. The pre-dried water-containing material will be transported to the drying furnace through the material transportation device. The water washing tower is connected to the pre-drying device through the pre-drying pipeline. When the tail gas after heat exchange is not needed for heating, the tail gas after heat exchange can directly enter the pre-drying device through the pre-drying pipeline.

[0056] Specifically, the part to be heated is a factory building.

[0057] In some embodiments, the invention further comprises: a heat exchanger and a third heat supply pipeline. The third heat supply pipeline and the first heat supply pipeline are suitable for heat exchange through the heat exchanger, the third heat supply pipeline has a second heat exchange medium, and the third heat supply pipeline passes through the portion to be heated.

[0058] In this embodiment, the third heating pipeline and the first heating pipeline are respectively connected to the heat exchanger, the first heat exchange medium exchanges heat with the second heat exchange medium in the heat exchanger, both ends of the third heating pipeline are respectively connected to the heat exchanger, the third heating pipeline passes through the part to be heated, and the second heat exchange medium after heat exchange flows out of the heat exchanger, passes through the part to be heated, and enters the heat exchanger again.

[0059] In some embodiments, the method further comprises: a sedimentation tank. The first heat supply pipeline is connected to the sedimentation tank, and the sedimentation tank is connected to the heat exchange device through a pipeline.

[0060] In this embodiment, the first heating pipeline is connected to the heat exchanger and the sedimentation tank respectively. The first heat exchange medium after heat exchange in the heat exchanger will enter the sedimentation tank through the first heating pipeline. The first heat exchange medium can precipitate impurities in the sedimentation tank. The sedimentation tank is connected to the spray structure in the water washing tower through the first heating pipeline. The first heating pipeline is connected in series with the spray structure, the heat exchanger and the sedimentation tank to form a complete closed-loop passage.

[0061] Preferably, the sedimentation tank is a tertiary sedimentation tank.

[0062] In some embodiments, the invention further comprises: a sewage treatment device connected to the sedimentation tank.

[0063] In this embodiment, the sewage treatment device is connected to the sedimentation tank. Since there is water vapor in the exhaust gas, when the first heat exchange medium exchanges heat with the exhaust gas, the water vapor will condense into liquid water due to cooling and flow with the first heat exchange medium. Therefore, the volume of the first heat exchange medium is constantly increasing. When a large amount of the first heat exchange medium enters the sedimentation tank, it will cause overflow. The sewage treatment device can recycle the excess sewage in the sedimentation tank for purification.

[0064] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for recovering waste heat from tail gas, characterized in that: The following steps are involved: The water-containing material enters the drying furnace, and the dried material is discharged from the drying furnace, and the tail gas generated during drying is collected; The tail gas enters the heat exchange device to exchange heat with the first heat exchange medium, and the first heat exchange medium provides heat after heat exchange. After the first heat exchange medium completes heat supply, it enters the heat exchange device to continue heat exchange, and the tail gas exchanges heat with the first heat exchange medium to provide heat. After the heat supply is completed, the tail gas enters the pre-drying device to pre-dry the water-containing material, or the tail gas after heat exchange directly enters the pre-drying device to pre-dry the water-containing material.

2. The tail gas waste heat recovery method according to claim 1, characterized in that: The first heat exchange medium and the second heat exchange medium exchange heat in the heat exchanger after heat exchange, the second heat exchange medium provides heat after heat exchange, and the second heat exchange medium returns to the heat exchanger to continue heat exchange; The first heat exchange medium after heat exchange in the heat exchanger returns to the heat exchange device to exchange heat with the tail gas.

3. The tail gas waste heat recovery method according to claim 1, characterized in that: When the exhaust gas enters the heat exchange device for heat exchange, the dust and odor in the exhaust gas can be removed.

4. The tail gas waste heat recovery method according to claim 3, characterized in that: When the first heat exchange medium exchanges heat with the exhaust gas, the first heat exchange medium removes dust and odor in the exhaust gas.

5. The tail gas waste heat recovery method according to claim 4, characterized in that: After the heat supply is completed, the first heat exchange medium enters the sedimentation tank to precipitate the impurities carried. After the precipitation is completed, the first heat exchange medium enters the heat exchange device to exchange heat with the tail gas.

6. The tail gas waste heat recovery method according to claim 1, characterized in that: The exhaust gas that has completed pre-drying enters the emission device for discharge, and the water-containing material that has completed pre-drying enters the drying furnace for drying.

7. A tail gas waste heat recovery system, applied to the tail gas waste heat recovery method described in any one of claims 1 to 6, characterized in that: include: Drying furnace; A heat exchange device, the heat exchange device is connected to the drying furnace through a pipeline, and the tail gas in the drying furnace is suitable for entering the heat exchange device through the pipeline; A first heat supply pipeline, both ends of which are respectively connected to the heat exchange device, a first heat exchange medium is contained in the first heat supply pipeline, and the first heat supply pipeline passes through the portion to be heated; a second heat supply pipeline, one end of which is connected to the heat exchange device, the second heat supply pipeline passes through the portion to be heated, and the exhaust gas is suitable for being heated by the second heat supply pipeline; A pre-drying device, wherein the pre-drying device is connected to the drying furnace through a material transportation device, the pre-drying device is connected to the other end of the second heating pipeline, or is connected to the heat exchange device through a pre-drying pipeline, and the exhaust gas is suitable for entering the pre-drying device through the second heating pipeline or entering the pre-drying device through the pre-drying pipeline.

8. The exhaust gas waste heat recovery system according to claim 7, characterized in that: Also includes: Heat exchangers; A third heating pipeline, the third heating pipeline and the first heating pipeline are suitable for heat exchange through the heat exchanger, the third heating pipeline has a second heat exchange medium, and the third heating pipeline passes through the part to be heated.

9. The exhaust gas waste heat recovery system according to claim 7, characterized in that: Also includes: A sedimentation tank, wherein the first heat supply pipeline is connected to the sedimentation tank, and the sedimentation tank is connected to the heat exchange device through a pipeline.

10. The exhaust gas waste heat recovery system according to claim 9, characterized in that: Also includes: A sewage treatment device is connected to the sedimentation tank.

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