Condensation trapping system and condensation trapping method

Abstract

The invention provides a condensation trapping system which comprises a plurality of condensation traps and a vortex tube group, and the vortex tube group comprises a compressed gas inlet, a low-temperature air outlet and a high-temperature air outlet; the low-temperature air outlet is communicated with the plurality of condensation traps, and the high-temperature air outlet is communicated with the plurality of condensation traps. According to the condensation trapping system, the compressed air and the vortex tube set are used for generating low-temperature air and high-temperature air which serve as a refrigerant and a heating medium respectively, the multiple condensation traps in the condensation trapping system are matched for periodic switching to trap high-temperature reaction gas-phase products, the under-pressure attribute of the compressed air is effectively utilized, generation of the cold medium and the heating medium is completed, and the condensation trapping effect is good. The process procedure for manufacturing the cold medium and the heat medium is greatly simplified, the problem that a conduction oil system needs to be introduced in the prior art is solved, and the equipment investment, the occupied area and the operation cost are saved. In addition, the compressed gas after heat exchange can also be reused as an oxidation reaction raw material, so that the heat recovered by the condensation trap is fully utilized.

Description

Technical Field

[0001] The present invention belongs to the technical field of condensation capture in the petrochemical industry, and specifically relates to a condensation capture system. In addition, the present invention also relates to a condensation capture method using the condensation capture system. Background Art

[0002] In the existing chemical production process of air high temperature oxidation method, such as the production process of phthalic anhydride, the reaction product is mixed in the high temperature gas phase discharged from the reactor in gaseous form, and the concentration is not high. The existing process utilizes the characteristics of desublimation of the reaction product and adopts a fin-type condensation trap (such as Figure 1 The reaction products are condensed and captured by the heat exchange tubes of the condensation trap (as shown), that is, the refrigerant (such as chilled water) is introduced into the heat exchange tubes of the condensation trap, and the heat exchange fins welded on the heat exchange tubes are continuously cooled by the refrigerant to maintain a low temperature. Therefore, when the reaction products contact the heat exchange fins, they condense or sublimate and stick to the heat exchange fins. After a certain amount of reaction products are mounted on the heat exchange fins of the condensation trap and a certain saturation is reached, a heat medium (such as heat transfer oil, steam, hot water, etc.) is introduced at this time to melt the reaction products mounted on the fins and flow downward into the collection tank under the action of gravity. In the existing process, the refrigerant is generally required to have a temperature of -10°C or even lower, and the heat medium needs to be as high as 120°C or even higher.

[0003] At present, the cold and hot utilities commonly used in the chemical industry cannot use the same medium to provide refrigerant and heat medium with such a temperature span. Therefore, there are two common practices. One is to design heat exchange tubes for the cold and hot media separately, so that the collector structure is bound to be more complicated, increasing the equipment cost; the other is to use the same special brand of heat transfer oil for the cold and hot media, but it needs to be equipped with a set of equipment including heaters, coolers, pumps, valves, buffer tanks, etc. to form a closed circulation system of heat transfer oil, which also greatly increases the investment, land occupation and operating costs.

[0004] In view of this, developing a refrigerant and a heat medium that can provide such a temperature span using the same medium has become an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and provide a condensation capture system, which uses a vortex tube group as a cold and hot medium generator, which converts and separates the input normal temperature compressed air into a low-temperature air and a high-temperature air, and respectively serves as a cold medium and a hot medium to realize the condensation capture and heating and melting collection of the condensation capture system.

[0006] The present invention is achieved through the following technical solutions:

[0007] One of the objects of the present invention is to provide a condensation capture system, comprising:

[0008] multiple condensation traps;

[0009] The vortex tube group includes a compressed gas inlet, a low-temperature air outlet and a high-temperature air outlet; the low-temperature air outlet is connected to a plurality of the condensation collectors, and the high-temperature air outlet is connected to a plurality of the condensation collectors.

[0010] In a preferred embodiment of the present invention, a control valve is provided at the high-temperature air outlet.

[0011] In a preferred embodiment of the present invention, the vortex tube group includes a plurality of vortex tubes arranged in parallel.

[0012] In a preferred embodiment of the present invention, the plurality of condensation traps are all connected to the oxidation reaction unit.

[0013] In a preferred embodiment of the present invention, each of the condensate collectors is provided with a cold / hot medium inlet pipeline, and the cold / hot medium inlet pipeline is respectively connected to a low-temperature air outlet pipeline provided at a low-temperature air outlet and a high-temperature air outlet pipeline provided at a high-temperature air outlet;

[0014] A three-way valve is provided at the connection of the cold / hot medium inlet pipeline, the low-temperature air outlet pipeline, and the high-temperature air outlet pipeline; the first inlet of the three-way valve is connected to the low-temperature air outlet pipeline, the second inlet is connected to the high-temperature air outlet pipeline, and the outlet of the three-way valve is connected to the cold / hot medium inlet pipeline.

[0015] The second object of the present invention is to provide a condensation capture method, using the condensation capture system described in one of the objects of the present invention to perform condensation capture, comprising:

[0016] S1: Compressed air is introduced into the vortex tube group to separate low-temperature air and high-temperature air;

[0017] S2: passing low-temperature air and high-temperature air into different condensation collectors respectively;

[0018] S3: according to the state of the material in the condensation collector, the low-temperature air is switched to the high-temperature air, and the high-temperature air is switched to the low-temperature air.

[0019] In a preferred embodiment of the present invention, the number of condensation traps into which low-temperature air is introduced is greater than the number of condensation traps into which high-temperature air is introduced.

[0020] In a preferred embodiment of the present invention, the pressure of the compressed air is 0.5-1.0 MPaG.

[0021] In a preferred embodiment of the present invention, the temperature of the low-temperature air is -15 to -25°C; and / or

[0022] The temperature of the high temperature air is 120-130°C.

[0023] In a preferred embodiment of the present invention, the method further comprises:

[0024] S4: Transferring the low-temperature air and high-temperature air after heat exchange in the multiple condensation traps to the oxidation reaction unit.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The condensation capture system of the present invention uses compressed air and a vortex tube group to generate low-temperature air and high-temperature air, which are used as refrigerant and heat medium respectively, and then cooperates with multiple condensation collectors in the condensation capture system to switch periodically to capture high-temperature reaction gas products. This method effectively utilizes the pressure-carrying property of compressed air to complete the generation of cold and heat medium, greatly simplifies the process of manufacturing cold and heat medium, solves the problem of the need to introduce a heat transfer oil system in the prior art, and saves equipment investment, land occupation and operating costs. In addition, the compressed gas after heat exchange can also be reused as an oxidation reaction raw material to make full use of the heat recovered by the condensation collector. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of a condensation trap in the prior art;

[0028] Figure 2 is a schematic diagram of a refrigerant capture system of the present invention;

[0029] In the figure, 1-condensation collector shell; 2-heat exchange tube; 3-heat exchange fin; 4-process gas phase inlet; 5-process gas phase outlet; 6-process liquid phase outlet; 7-cold / hot medium inlet; 8-cold / hot medium outlet. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0031] The present invention provides a condensation trapping system, comprising a vortex tube group and a plurality of condensation traps. Figure 2 As shown, the condensate trap system includes a vortex tube group and a first condensate trap (i.e., condensate trap 1#), a second condensate trap (i.e., condensate trap 2#), and a third condensate trap (i.e., condensate trap 3#); wherein the first condensate trap, the second condensate trap, and the third condensate trap are arranged from left to right in sequence. It should be noted that, Figure 2 The first condensation trap, the second condensation trap, and the third condensation trap do not constitute a limitation of the present invention, but are only exemplary descriptions. The technicians can set a suitable number of condensation traps according to the upstream material conditions.

[0032] The vortex tube group serves as a cold and heat medium generator, and preferably includes a plurality of vortex tubes arranged in parallel to provide cold and heat media with a large temperature span. It should be noted that the number of vortex tubes in the vortex tube group is associated with the actually required cold medium temperature and heat medium temperature, and the present invention does not limit the number thereof. Those skilled in the art can set it according to actual needs.

[0033] The vortex tube group is provided with one inlet and two outlets. The inlet is a compressed gas inlet, and the two outlets are a low-temperature air outlet and a high-temperature air outlet respectively. After compressed air (from a compressor or an off-site utility pipeline) enters the vortex tube group, it rotates and flows towards the high-temperature air outlet of the vortex tube group. A part of the high-temperature air moves to the high-temperature air outlet. After the remaining low-temperature air is blocked, it rotates in the reverse direction at the same speed and flows towards the low-temperature air outlet of the vortex tube group. During this process, heat exchange occurs between the low-temperature air and the high-temperature air. The inner-ring air flow becomes very cold and moves in the reverse direction to the low-temperature air outlet of the vortex tube group, while the outer-ring air flow becomes very hot and moves to the high-temperature air outlet of the vortex tube group.

[0034] The process of separating high-temperature gas and low-temperature gas by the vortex tube group is an adiabatic and isenthalpic process, and the ratio of high-temperature gas and low-temperature gas can be adjusted. In a preferred embodiment of the present invention, a control valve is provided at the high-temperature air outlet. By adjusting the opening degree of the control valve, the ratio of high-temperature gas and low-temperature gas is adjusted, and thus the temperatures of high-temperature gas and low-temperature gas are controlled. That is, the temperatures of high-temperature gas and low-temperature gas can be controlled by adjusting the opening degree of the control valve. For example, when the temperature of the required low-temperature gas is relatively low, the opening degree of the control valve can be reduced, so that the temperature of the high-temperature gas is further increased and the temperature of the low-temperature gas is further decreased; when the temperature of the required low-temperature gas is relatively high, the opening degree of the control valve can be increased, so that the temperature of the high-temperature gas is further decreased and the temperature of the low-temperature gas is further increased.

[0035] The low-temperature air outlets of the vortex tube group are respectively connected to the first condensation trap (i.e., condensation trap 1#), the second condensation trap (i.e., condensation trap 2#), and the third condensation trap (i.e., condensation trap 3#). The low-temperature gas can enter the first condensation trap, the second condensation trap, and the third condensation trap (i.e., condensation trap 3#) respectively from the low-temperature gas outlet of the vortex tube group to serve as a cold medium to realize the condensation and trapping of the materials therein.

[0036] The high-temperature air outlets of the vortex tube group are respectively connected to the first condensation trap (i.e., condensation trap 1#), the second condensation trap (i.e., condensation trap 2#), and the third condensation trap (i.e., condensation trap 3#). The high-temperature gas can enter the first condensation trap, the second condensation trap, and the third condensation trap (i.e., condensation trap 3#) respectively from the high-temperature gas outlet of the vortex tube group to serve as a heat medium to realize the heating and melting of the materials therein.

[0037] The condensate trap needs to be periodically introduced with refrigerant and heat medium. Explanatoryally, "periodic introduction of refrigerant and heat medium" means that for the same condensate trap, refrigerant can be introduced first, and after a certain amount of reaction products are mounted on the heat exchange fins of the condensate trap, the introduction of refrigerant is stopped; secondly, heat medium is introduced, and the reaction products mounted on the fins melt and flow downward under the action of gravity and then collected. After the collection is completed, the introduction of heat medium is stopped; again, refrigerant is introduced again, and heat medium is introduced again after a certain amount of reaction products are mounted on the heat exchange fins of the condensate trap. This repeated process is the periodic introduction of refrigerant and heat medium. Multiple condensate traps are arranged in parallel, which can realize periodic switching between condensation capture and heating and melting states on the one hand, and continuous capture of material capture on the other hand.

[0038] In a preferred embodiment of the present invention, at the same time, most condensation traps are in a condensation trapping state with refrigerant introduced, and a small number of condensation traps are in a heating, melting, and collecting state with heat introduced. Therefore, three condensation traps are selected as an exemplary description in this embodiment, which does not constitute a limitation on the number of condensation traps that are "in a condensation trapping state" and "in a heating, melting, and collecting state". For the same condensation trap, the time required for the condensation trapping process is generally longer than the time required for heating and melting, so the number of condensation traps that need to be introduced with refrigerant is greater than the number of condensation traps that need to be introduced with heat.

[0039] It should be noted that at the same time, most condensation traps are in the condensation trapping state with refrigerant introduced, which means that the amount of low-temperature air diversion is greater than the amount of high-temperature air diversion, but this does not affect the cooling effect on the condensation trap. This is because the volume of low-temperature air generated after passing through the vortex tube group is several times the volume of high-temperature gas.

[0040] by Figure 2 Taking the condensate trap 1#, condensate trap 2# and condensate trap 3# in the example, the realization of continuous capture of materials is illustrated. Condensate trap 1# and condensate trap 2# are in the condensation capture state with the refrigerant introduced, and condensate trap 3# is in the heating, melting and collecting state with the heat medium just introduced. It should be noted that although condensate trap 1# and condensate trap 2# are both in the condensation capture state with the refrigerant introduced, their processes are different; specifically, condensate trap 1# has just been introduced with the refrigerant, while condensate trap 2# has been introduced with the refrigerant for some time.

[0041] When the reaction products are condensed and trapped in condensation trap 1# and condensation trap 2#, a certain amount of reaction products have been mounted on the heat exchange fins of condensation trap 3#, and they begin to be heated and undergo phase transformation under the action of the heat medium. As time goes by, the reaction products on the heat exchange fins of condensation trap 3# melt and flow downward under the action of gravity, and are extracted and collected at the process liquid phase outlet located on the bottom surface of condensation trap 3#.

[0042] After condenser trap 3# has been melted for a period of time, a certain amount of reaction products have been mounted on the heat exchange fins of condenser trap 2#; at this time, stop introducing refrigerant into condenser trap 2# and start introducing heat medium into it; the reactants on the heat exchange fins of condenser trap 2# begin to be heated and undergo phase transformation.

[0043] When the reaction products of condensate trap 3# are all melted and taken out, condensate trap 3# can no longer collect the reaction products; at this time, stop introducing heat medium into condensate trap 3#, start introducing refrigerant into it, and continue to mount the reaction products. At the same time, the reactants on the heat exchange fins of condensate trap 2# have partially melted into liquid phase, that is, the reaction products can be collected from condensate trap 2#.

[0044] After condenser trap 2# has collected the reaction products for a period of time, a certain amount of reaction products have been mounted on the heat exchange fins of condenser trap 1#; at this time, stop introducing refrigerant into condenser trap 1# and start introducing heat medium into it; the reactants on the heat exchange fins of condenser trap 1# begin to be heated and undergo phase transformation.

[0045] When all the reaction products of condensate trap 2# are melted and taken out, condensate trap 2# can no longer collect reaction products; at this time, stop introducing heat medium into condensate trap 2#, start introducing refrigerant into it, and continue to mount reaction products. At the same time, the reactants on the heat exchange fins of condensate trap 1# have begun to melt into liquid phase, that is, the reaction products can be collected from condensate trap 1#.

[0046] As described above, as time progresses, the reaction products can be collected in sequence from condensation trap 3#, condensation trap 2#, and condensation trap 1#, ultimately achieving continuous capture of the reaction products and shortening the product collection cycle.

[0047] The structures of the first condensation trap, the second condensation trap and the third condensation trap are the same as those in the prior art. Figure 1 As shown, it includes a condensate collector shell 1, a heat exchange tube 2, a heat exchange fin 3, a process gas phase inlet 4, a process gas phase outlet 5, a process liquid phase outlet 6, a cold / hot medium inlet 7, and a cold / hot medium outlet 8; wherein the gas phase reaction product enters the condensate collector from the process gas phase inlet 4. Since the structure of the condensate collector is the same as that of the prior art, it will not be described here.

[0048] The low-temperature air outlet is connected to the plurality of condensation traps, and the high-temperature air outlet is connected to the plurality of condensation traps. Specifically in this embodiment, the low-temperature air outlet and the high-temperature air outlet of the vortex tube group are both connected to the cold / heat medium inlet 7 of the first condensation trap (i.e., condensation trap 1#), the second condensation trap (i.e., condensation trap 2#), and the third condensation trap (i.e., condensation trap 3#).

[0049] In one preferred embodiment of the present invention, a cold / hot medium inlet pipeline is provided at the cold / hot medium inlet 7 of each condensation trap, and the inlet pipeline is respectively connected to a low-temperature air outlet pipeline provided at the low-temperature air outlet and a high-temperature air outlet pipeline provided at the high-temperature air outlet. A three-way valve is provided at the connection of the cold / hot medium inlet pipeline, the low-temperature air outlet pipeline, and the high-temperature air outlet pipeline. The three-way valve is provided with two inlets and one outlet, the first inlet of the three-way valve is connected to the low-temperature air outlet pipeline, the second inlet is connected to the high-temperature air outlet pipeline, and the outlet of the three-way valve is connected to the cold / hot medium inlet pipeline, which is convenient for switching the cold medium and the hot medium entering the condensation trap on the one hand, and saves a part of the pipeline on the other hand.

[0050] It should be noted that when the three-way valve is switched from the second inlet to the first inlet, low-temperature air enters the corresponding condensate collector, and when the three-way valve is switched from the first inlet to the second inlet, high-temperature air enters the corresponding condensate collector.

[0051] In another preferred embodiment of the present invention, the first condensation trap, the second condensation trap, and the third condensation trap are all connected to the oxidation reaction unit; specifically, the cold / hot medium outlets 8 in the first condensation trap, the second condensation trap, and the third condensation trap are all connected to the oxidation reaction unit. After heat exchange, the low-temperature gas and the high-temperature gas can still be used as feeds for the oxidation reaction unit to make full use of the heat recovered by the condensation trap. Specifically, the gas after heat exchange in the first condensation trap, the second condensation trap, and the third condensation trap still maintains a certain pressure, and it does not contact the process medium during the heat exchange process, so it can be transferred to the oxidation reaction unit and reused as a raw material for the oxidation reaction.

[0052] Example 1

[0053] This embodiment provides a specific application of the condensation capture system of the present invention for condensation capture of terephthalaldehyde.

[0054] Para-xylene and air are mixed and catalytically oxidized to form terephthalaldehyde under the conditions of high temperature of 350-450°C and low pressure of 0.05MPaG. The content of terephthalaldehyde in the reaction product is between 0.5% and 3%. The melting point of para-xylene is 114-116°C and the boiling point is 245-248°C. It has the characteristics of sublimation and condensation, and is therefore suitable for condensation and capture by the condensation capture system of the present invention.

[0055] The gas phase at the oxidation reaction outlet is cooled to 270-300°C by a cooler, and enters condensation trap 1# and condensation trap 2# in a condensation and trapping state through process gas phase inlet 4 of condensation trap 1# and condensation trap 2#, respectively.

[0056] The vortex tube group is fed with 0.7MPaG normal temperature compressed air to produce a cold and hot separation effect, separating low temperature air of -15 to -25°C and high temperature air of 120 to 130°C. The low temperature air is transferred to the condensation trap 1# and condensation trap 2# in the condensation trap state; the high temperature air is transferred to the condensation trap 3# in the heating and melting state.

[0057] At this time, the heat exchange tubes 2 and the heat exchange fins 3 in the condensation trap 1# and the condensation trap 2# are cooled to -10 to -5°C, so that the terephthalaldehyde in the gas phase reaction product condenses and sublimates, and changes from the gas phase to the solid phase and adheres to the heat exchange fins 3.

[0058] In the condensation trap process before switching, the heat exchange fins 3 of the condensation trap 3# are already covered with terephthalaldehyde solid phase. At this time, the heat exchange tubes 2 in the condensation trap 3# are heated to 120-130°C by the high-temperature air, so that the terephthalaldehyde melts quickly and flows to the bottom of the condensation trap 3# under the action of gravity, and flows out from the process liquid phase outlet 6 into the next unit.

[0059] In addition, the compressed air after heat exchange in condenser trap 1#, condenser trap 2#, and condenser trap 3# can still maintain a pressure of 0.1-0.3MpaG, and after being combined, it is transported to the oxidation reaction unit through a pipeline for use as oxidation feed.

[0060] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0062] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A condensation capture system, Features: include: multiple condensation traps; The vortex tube group includes a compressed gas inlet, a low-temperature air outlet and a high-temperature air outlet; the low-temperature air outlet is connected to a plurality of the condensation collectors, and the high-temperature air outlet is connected to a plurality of the condensation collectors.

2. The condensate capture system according to claim 1, Features: A control valve is provided at the high-temperature air outlet.

3. The condensation capture system according to claim 1, Features: The vortex tube group includes a plurality of vortex tubes arranged in parallel.

4. The condensate capture system according to claim 1, Features: The plurality of condensation traps are all connected to the oxidation reaction unit.

5. The condensation capture system according to claim 1, Features: Each of the condensate collectors is provided with a cold / hot medium inlet pipeline, and the cold / hot medium inlet pipeline is respectively connected to a low-temperature air outlet pipeline provided at a low-temperature air outlet and a high-temperature air outlet pipeline provided at a high-temperature air outlet; A three-way valve is provided at the connection of the cold / hot medium inlet pipeline, the low-temperature air outlet pipeline, and the high-temperature air outlet pipeline; the first inlet of the three-way valve is connected to the low-temperature air outlet pipeline, the second inlet is connected to the high-temperature air outlet pipeline, and the outlet of the three-way valve is connected to the cold / hot medium inlet pipeline.

6. A condensation capture method, Features: Condensation capture is performed using the condensation capture system according to any one of claims 1 to 5, comprising: S1: Compressed air is introduced into the vortex tube group to separate low-temperature air and high-temperature air; S2: passing low-temperature air and high-temperature air into different condensation collectors respectively; S3: according to the state of the material in the condensation collector, the low-temperature air is switched to the high-temperature air, and the high-temperature air is switched to the low-temperature air.

7. The method according to claim 6, Features: The number of condensation traps into which low-temperature air is introduced is greater than the number of condensation traps into which high-temperature air is introduced.

8. The method according to claim 6, Features: The pressure of the compressed air is 0.5-1.0 MPaG.

9. The method according to claim 6, Features: The temperature of the low temperature air is -15 to -25°C; and / or The temperature of the high temperature air is 120-130°C.

10. The method according to claim 6, Features: The method further comprises: S4: Transferring the low-temperature air and high-temperature air after heat exchange in the multiple condensation traps to the oxidation reaction unit.

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