A propane dehydrogenation reaction system and a propane dehydrogenation reaction process

Abstract

The present application provides a kind of propane dehydrogenation reaction system and propane dehydrogenation reaction process, propane dehydrogenation reaction is carried out using the system and process of the present application, can reduce the emission of carbon dioxide and waste water, while a large amount of heat can be recovered, reduce energy consumption, green environmental protection.The system includes feed heating furnace, heat recovery unit, reaction unit, gas-liquid separation unit, waste water treatment unit, gas phase product post-processing unit;Feed heating furnace is used to heat propane feed;Heat recovery unit is used to make flue gas and water phase heat exchange, and first gas phase and first liquid phase are obtained by separation;The reaction unit is used to make propane feed and first gas phase reaction;Gas-liquid separation unit is used to treat product stream and first liquid phase, to obtain gas phase product and oil-containing waste water;Waste water treatment unit is used to treat oil-containing waste water;Gas phase product post-processing unit is used for drying and cryogenic separation to gas phase product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of propane dehydrogenation process, and in particular to a propane dehydrogenation reaction system and a propane dehydrogenation reaction process. BACKGROUND

[0002] The propane dehydrogenation reaction temperature is high and is an endothermic reaction, so the feed propane needs to be preheated and heat needs to be continuously supplemented during the reaction process. The current mainstream processes are UOP moving bed process and LUMMUS fixed bed process, both of which use a propane feed heating furnace to preheat the raw materials. UOP uses an interstage heating furnace to supplement heat during the reaction process, and LUMMUS uses a regenerative air heating furnace to heat the regenerative air, which then enters the reactor with heat, and at the same time, the heat generated by the decoking process is used to supplement the reaction. Regardless of which heating method is used, burning fuel gas will produce a large amount of carbon dioxide, and at the same time, using natural aspiration for the heating furnace will also heat the nitrogen in the air, and considering the dew point corrosion problem during the exhaust process, the exhaust gas needs to be discharged at a temperature of about 110°C, which will result in a certain waste of energy.

[0003] Currently, the propane dehydrogenation devices that have been industrialized all use direct dehydrogenation, but as the coking problem during industrial operation is difficult to solve, oxidative dehydrogenation has gradually attracted attention.

[0004] Chinese patent application CN114659374A introduces a propane dehydrogenation device flue gas utilization method, which mainly re-pumps the flue gas discharged from the waste heat boiler, mixes in oxygen, and then re-enters the reactor as regeneration gas for regeneration. This method can reduce the amount of regeneration air used and recover part of the heat of the flue gas, thereby reducing the overall energy consumption of the device. However, the recovered flue gas contains some NOx and water, and if the recovered flue gas is below the dew point temperature, it may cause equipment corrosion. In addition, the flue gas recovery process also requires the use of a regeneration air compressor for pressurization and other operations, and the energy consumption of the device is reduced by a small amount.

[0005] Chinese patent application CN115745741A discloses a propane dehydrogenation and carbon dioxide hydrogenation synthesis of methanol coupling system and process. It obtains high-purity carbon dioxide by a series of water removal, sulfur removal, carbon dioxide capture, and recovery operations on the flue gas of a gas boiler, and uses the hydrogen generated by dehydrogenation to produce methanol. This method can reduce the carbon emissions of propane dehydrogenation, but the route for obtaining carbon dioxide is complex, which increases the cost of methanol processing. SUMMARY

[0006] The present application provides a propane dehydrogenation reaction system and a propane dehydrogenation reaction process, which can reduce the emission of carbon dioxide and waste water, even achieve the purpose of zero emission, and can recover a large amount of heat, reduce energy consumption and be green and environmentally friendly.

[0007] To achieve the purpose, the present application provides the following technical solutions:

[0008] The present application provides a propane dehydrogenation reaction system, which comprises a feed heating furnace, a heat recovery unit, a reaction unit, a gas-liquid separation unit, a waste water treatment unit and a gas phase product post-treatment unit.

[0009] The feed heating furnace is used for heating propane feed by burning fuel to obtain heated propane feed and flue gas.

[0010] The heat recovery unit is used for heat exchange between the flue gas and the water phase obtained in the waste water treatment unit to obtain cooled flue gas and preheated water phase, and the cooled flue gas is subjected to gas-liquid separation to obtain a first gas phase and a first liquid phase.

[0011] The reaction unit comprises a reactor, which is used for reacting the heated propane feed and the first gas phase in the presence of a catalyst to obtain a product stream comprising propylene, propane, hydrogen and carbon monoxide.

[0012] The gas-liquid separation unit is used for treating the product stream and the first liquid phase to obtain a gas phase product and obtain oil-containing waste water comprising heavy hydrocarbons and water.

[0013] The waste water treatment unit is used for treating the oil-containing waste water to obtain a water phase and an oil phase.

[0014] The gas phase product post-treatment unit is used for drying and cryogenic separation of the gas phase product to obtain a liquid phase carbon three product and a by-product light component.

[0015] The gas phase product post-treatment unit and the waste water treatment unit are respectively connected with the feed heating furnace, and the by-product light component and the oil phase are sent into the feed heating furnace as the fuel.

[0016] Preferably, the heat recovery unit is connected with a convection section of the feed heating furnace to heat exchange between the preheated water phase and the flue gas flowing through the convection section and obtain steam.

[0017] Preferably, the flue gas outlet of the feed heating furnace is connected with a flue gas discharge pipe.

[0018] The heat recovery unit comprises a non-phase change heat exchanger, a phase change heat exchanger and a gas-liquid separation device; and along the flow direction of the flue gas in the flue gas discharge pipe, the non-phase change heat exchanger, the phase change heat exchanger and the gas-liquid separation device are connected in series through the flue gas discharge pipe.

[0019] The wastewater treatment unit is connected with a water phase conveying pipe for outputting the water phase, and the water phase conveying pipe is connected with the phase change heat exchanger to make the water phase exchange heat with the flue gas flowing through the phase change heat exchanger and obtain the preliminarily preheated water phase.

[0020] The non-phase change heat exchanger is also connected with the water phase outlet of the phase change heat exchanger through a preliminarily preheated water phase output pipeline to make the preliminarily preheated water phase exchange heat with the flue gas flowing through the non-phase change heat exchanger and obtain the preheated water phase.

[0021] The gas-liquid separation device is used for gas-liquid separation of the flue gas output by the phase change heat exchanger to obtain the first gas phase and the first liquid phase.

[0022] Preferably, the reaction unit further comprises an in-out material heat exchanger for exchanging heat between the product stream before entering the gas-liquid separation unit and the propane feed before entering the feed heating furnace.

[0023] Preferably, the reaction unit further comprises a compressor feed cooler, which is arranged between the in-out material heat exchanger and the gas-liquid separation unit, for cooling the product stream output by the in-out material heat exchanger before entering the gas-liquid separation unit.

[0024] Preferably, the gas-liquid separation unit comprises multiple-stage gas-liquid separation tanks connected in series, and between two adjacent stages of gas-liquid separation tanks, a compressor and an inter-stage cooler are arranged in series between the gas phase outlet of the upstream gas-liquid separation tank and the feed inlet of the downstream gas-liquid separation tank.

[0025] Preferably, the wastewater treatment unit comprises a demulsifier and an oil removal coalescer.

[0026] The demulsifier is used for breaking the oil-in-water structure of the oil-containing wastewater.

[0027] The oil removal coalescer is used for treating the material after the demulsifier treatment and separating to obtain the water phase and the oil phase.

[0028] Preferably, the gas phase product post-treatment unit comprises a drying device and a cryogenic separation device.

[0029] The drying device is used for drying the gas phase product to remove water and hydrogen sulfide entrained in the gas phase product.

[0030] The cryogenic separation device is used for cryogenic separation of the gaseous phase product after the drying device to obtain a liquid phase carbon three product and the by-product light component.

[0031] The application also provides a process for carrying out the propane dehydrogenation reaction by using the propane dehydrogenation reaction system described above, comprising the following steps:

[0032] (1) feeding the propane feed into the feed heating furnace, providing heat by combustion of fuel in the feed heating furnace to heat the propane feed, to obtain a heated propane feed and flue gas; preferably, the feed heating furnace uses pure oxygen for combustion support;

[0033] (2) feeding the flue gas into the heat recovery unit to exchange heat with the aqueous phase obtained in the wastewater treatment unit, to obtain cooled flue gas and preheated aqueous phase; carrying out gas-liquid separation on the cooled flue gas to obtain a first gaseous phase and a first liquid phase;

[0034] (3) reacting the heated propane feed and the first gaseous phase in the presence of a catalyst in the reactor of the reaction unit to obtain a product stream comprising propylene, propane, hydrogen and carbon monoxide;

[0035] (4) feeding the product stream and the first liquid phase into the gas-liquid separation unit for treatment to obtain a gaseous phase product, and separating out an oily wastewater containing heavy hydrocarbons and water;

[0036] feeding the gaseous phase product into the gaseous phase product post-treatment unit for drying and cryogenic separation to obtain a liquid phase carbon three product and a by-product light component; feeding the by-product light component into the feed heating furnace of step (1) for combustion as fuel;

[0037] (5) feeding the oily wastewater into the wastewater treatment unit for treatment to obtain an aqueous phase and an oil phase; circulating the aqueous phase to the heat recovery unit of step (2) for the heat exchange; feeding the oil phase into the feed heating furnace of step (1) for combustion as fuel.

[0038] Preferably, the process further comprises the following steps:

[0039] In step (2), the preheated aqueous phase is fed into the convection section of the feed heating furnace to exchange heat with the flue gas, so that the preheated aqueous phase is converted into steam;

[0040] And / or, in step (2), in the heat recovery unit, the flue gas flows through a non-phase heat exchanger, a phase heat exchanger in sequence, and then enters a gas-liquid separation device to carry out gas-liquid separation to obtain the first gas phase and the first liquid phase; in the phase heat exchanger, the flue gas exchanges heat with the water phase obtained in the wastewater treatment unit to obtain a preliminarily preheated water phase; in the non-phase heat exchanger, the flue gas exchanges heat with the preliminarily preheated water phase to obtain the preheated water phase;

[0041] And / or, in step (1), the propane feed for feeding into the feed heating furnace is preliminarily exchanged heat with the product stream output from the reactor in a feed and product heat exchanger; preferably, after the heat exchange in the feed and product heat exchanger, the product stream is sent into a compressor feed cooler to be cooled, and then is sent into the gas-liquid separation unit.

[0042] And / or, in step (5), the oily wastewater is first sent into a demulsifier of the wastewater treatment unit to be demulsified, and then is sent into an oil-water separation coalescer of the wastewater treatment unit to be separated into the water phase and the oil phase.

[0043] The technical scheme provided by the present application has the following beneficial effects:

[0044] (1) Compared with the prior art, the system and process of the present application can reduce carbon dioxide and wastewater emissions, and is a new green and low-carbon reaction process for propane dehydrogenation reaction;

[0045] (2) The present application can convert high-carbon coking substances generated by high-temperature cracking and olefin polymerization into hydrogen and carbon monoxide through partial oxidation of carbon dioxide and water-gas reaction, thereby improving atomic utilization rate and avoiding energy and reaction time waste caused by catalyst regeneration;

[0046] (3) The present application can effectively recover flue gas heat, further reducing device energy consumption and production cost. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 A brief flow chart of the propane dehydrogenation reaction process in one embodiment;

[0048] Figure 2 A schematic diagram of the propane dehydrogenation reaction system in one embodiment;

[0049] Figure 3 A brief flow chart of the propane dehydrogenation reaction process in Comparative Example 1;

[0050] Figure 4 A schematic diagram of the propane dehydrogenation reaction system in Comparative Example 1. DETAILED DESCRIPTION

[0051] In order to facilitate the understanding of the present application, the present application will be further described below in conjunction with examples. It should be understood that the following examples are only for better understanding of the present application, and do not mean that the present application is limited to the following examples only.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. The terms "first", "second", etc. are used only for descriptive purposes and should not be construed as implying or suggesting relative importance.

[0053] The first aspect of the present application provides a propane dehydrogenation reaction system, referring to Figure 1 、 Figure 2 , the system mainly comprises a feed heating furnace 1, a heat recovery unit 100, a reaction unit 200, a gas-liquid separation unit 300, a wastewater treatment unit 500 and a gas phase product post-treatment unit 400.

[0054] The feed heating furnace 1 is used to provide heat by burning fuel, thereby heating the propane feed to obtain the heated propane feed and flue gas; specifically, the radiant section at the lower part of the feed heating furnace 1 is used to heat the propane feed, for example, from 452℃ to 590℃;

[0055] The heat recovery unit 100 is used to exchange heat between the flue gas output by the feed heating furnace 1 and the aqueous phase obtained in the wastewater treatment unit 500, thereby obtaining the cooled flue gas and the preheated aqueous phase, and also making the cooled flue gas obtain the first gas phase and the first liquid phase through gas-liquid separation; the heat recovery unit 100 realizes the recovery and utilization of the waste heat of the flue gas;

[0056] The reaction unit 200 comprises a reactor 5, which is used to make the heated propane feed and the first gas phase react in the presence of a catalyst to obtain a product stream comprising propylene, propane, hydrogen and carbon monoxide; the reactor 5 mainly performs the main reaction of propane dehydrogenation;

[0057] The gas-liquid separation unit 300 is used to process the product stream output by the reactor 5 and the first liquid phase output by the heat recovery unit 100, and obtain the gas phase product through gas-liquid separation, and also obtain the oily wastewater containing heavy hydrocarbons above C4 and water;

[0058] The wastewater treatment unit 500 is used to perform oil-water separation treatment on the oily wastewater separated in the gas-liquid separation unit 300, thereby obtaining the aqueous phase and the oil phase;

[0059] The gas phase product post-processing unit 400 is used for drying and cryogenic separation of the gas phase product in the gas-liquid separation unit 300, so as to obtain a liquid phase carbon three product and a by-product light component; wherein the by-product light component mainly includes methane, ethane, ethylene and hydrogen and the like;

[0060] The gas phase product post-processing unit 400 and the waste water treatment unit 500 are respectively connected with the feed heating furnace 1, and are used for sending the by-product light component separated from the gas phase product post-processing unit 400 and the oil phase separated from the waste water treatment unit 500 into the feed heating furnace 1 as the fuel, that is, as the source of the fuel.

[0061] The system is used for propane dehydrogenation reaction, and after the flue gas recovers heat in the heat recovery unit 100, the separated first gas phase is used as raw material and is fed into the reactor 5 together with the propane feed for dehydrogenation reaction. Through the weak oxidizing property of carbon dioxide and the dilution of propane, the conversion rate of propane can be improved, and the amount of carbon deposition in the reaction process can be reduced. At the same time, the oil phase and the water phase of the oil-containing waste water generated in the reaction process are separated by the waste water treatment unit 500, and the oil phase and the by-product light component separated from the gas phase product post-processing unit 400 are sent into the feed heating furnace 1 as fuel. Through the ingenious arrangement and mutual cooperation of each unit and the flow direction of each material in the whole process system, the carbon emission and waste water emission of the process system can be reduced, the energy consumption and fuel consumption of the device can be reduced through waste heat recovery and heavy hydrocarbon recovery, on the other hand, the reaction effect can be improved, and through the first gas phase separated after the reactor 5 is combined with the flue gas waste heat recovery, the occurrence of side reactions can be effectively reduced, and the selectivity and overall yield of propane can be improved. Based on the process system for propane dehydrogenation reaction, the carbon dioxide, waste water and waste oil emissions are less, and the heat utilization is sufficient, so that the energy consumption can be greatly reduced.

[0062] Further, the heat recovery unit 100 is connected with the convection section of the feed heating furnace 1, so that the preheated water phase obtained in the heat recovery unit 100 is subjected to heat exchange with the flue gas flowing through the convection section of the feed heating furnace 1, the preheated water phase is heated and converted into steam, which can be used for the separation system of the device.

[0063] Further, the flue gas outlet of the feed heating furnace 1 is connected with a flue gas discharge pipe 20, through which the flue gas in the feed heating furnace 1 is outputted. The heat recovery unit 100 preferably comprises a non-phase heat exchanger 2, a phase change heat exchanger 3 and a gas-liquid separation device 4; and along the flow direction of the flue gas in the flue gas discharge pipe 20, the non-phase heat exchanger 2, the phase change heat exchanger 3 and the gas-liquid separation device 4 are connected in series through the flue gas discharge pipe 20; the wastewater treatment unit 500 is connected with a water phase conveying pipe for outputting the water phase, which is connected with the phase change heat exchanger 3, so that the water phase exchanges heat with the flue gas flowing through the phase change heat exchanger 3, thereby obtaining a preliminarily preheated water phase and further cooled flue gas; the non-phase heat exchanger 2 is also connected with the water phase outlet of the phase change heat exchanger 3 through a preliminarily preheated water phase output pipe 21, so that the preliminarily preheated water phase exchanges heat with the flue gas flowing through the non-phase heat exchanger 2, thereby obtaining a preheated water phase and preliminarily cooled flue gas; the gas-liquid separation device 4 is connected with the flue gas outlet of the phase change heat exchanger 3, for gas-liquid separation of the flue gas outputted from the phase change heat exchanger 3, thereby obtaining a first gas phase and a first liquid phase. By making the flue gas flow through the non-phase heat exchanger 2 and the phase change heat exchanger 3 in sequence to fully recover the heat of the flue gas, which is used to preheat the circulating water to fully recover the heat of the flue gas, the heat efficiency of the feed heating furnace 1 can be improved. One is the non-phase heat exchanger 2, which is used to fully recover the heat of the flue gas while avoiding the problem of dew point corrosion caused by water liquefaction, so that the material grade of the heat exchanger can be reduced, thereby reducing the investment. The other is the phase change heat exchanger 3, which is used to fully recover the phase change heat of the water vapor in the flue gas, while the water liquefaction process removes the oxides of nitrogen and sulfur in the flue gas, thereby avoiding the corrosion of the subsequent reactor 5.

[0064] Preferably, the reaction unit 200 further comprises an inlet and outlet material heat exchanger 6, through which the product stream before entering the gas-liquid separation unit 300 exchanges heat with the propane feed before entering the feed heating furnace 1, so that the heat in the system is further utilized and the energy consumption is reduced. Preferably, the reaction unit 200 further comprises a compressor feed cooler 7, which is arranged between the inlet and outlet material heat exchanger 6 and the gas-liquid separation unit 300, for cooling the product stream after heat exchange through the inlet and outlet material heat exchanger 6 before entering the gas-liquid separation unit 300.

[0065] Preferably, the gas-liquid separation unit 300 comprises multiple-stage gas-liquid separation tanks 8, 11, 13 connected in series, and between any two adjacent stages, a compressor 9 and an inter-stage cooler 10 are arranged in series between the gas phase outlet of the upstream gas-liquid separation tank and the inlet of the downstream gas-liquid separation tank. Figure 2For example, there are primary gas-liquid separation tank 8, secondary gas-liquid separation tank 11 and tertiary gas-liquid separation tank 13, and a compressor 9 and an inter-stage cooler 10 are connected in series between the gas phase outlet of the primary gas-liquid separation tank 8 and the inlet of the secondary gas-liquid separation tank 11; similarly, a compressor 9 and an inter-stage cooler 10 are also connected in series between the gas phase outlet of the secondary gas-liquid separation tank 11 and the inlet of the tertiary gas-liquid separation tank 13. The oil-containing wastewater containing heavy hydrocarbons and water separated in each stage of the gas-liquid separation tank is sent to the wastewater treatment unit 500, and the gas phase product separated from the tertiary gas-liquid separation tank 13 is sent to the gas phase product post-treatment unit 400 for further treatment. By arranging the compressor 9, the drying effect of the subsequent drying device 14 can be improved by increasing the pressure, and the subsequent deep cooling separation device 15 can be facilitated.

[0066] Preferably, the wastewater treatment unit 500 comprises a demulsifier 16 and an oil removal coalescer 17; the demulsifier 16 is used to destroy the oil-in-water structure of the oil-containing wastewater; the oil removal coalescer 17 is used to treat the material after the demulsifier 16 treatment, and separate the water phase and the oil phase, wherein the water phase is sent to the heat recovery unit 100 for heat exchange with the flue gas, and then enters the convection section of the feed heating furnace 1 for further heating to convert into steam, and the oil phase is sent to the feed heating furnace 1 as fuel.

[0067] Preferably, the gas phase product post-treatment unit 400 comprises a drying device 14 and a cryogenic separation device 15. The drying device 14 is used to dry the gas phase product obtained from the gas-liquid separation unit 300, so as to remove water and hydrogen sulfide entrained in the gas phase product; the cryogenic separation device 15 is used to cryogenically separate the gas phase product treated by the drying device 14, so as to separate liquid phase carbon three product and by-product light components from the gas phase product. In the reactor 5, in order to prevent the inner wall of the reactor 5 from affecting the reaction, 3 g / h of dimethyl disulfide can be added for metal passivation. The dryer can use 5A molecular sieve or the like adsorption filler to remove water and hydrogen sulfide generated by the decomposition of dimethyl disulfide in the gas phase product obtained from the gas-liquid separation unit 300 in the reactor 5, which can reduce the corrosion risk of the downstream equipment and prevent the subsequent cryogenic treatment device from being frozen. The drying device 14 can adopt a drying device with corresponding functions known in the art, for example, can comprise a plurality of, for example, two dryers, and the drying operation and regeneration operation of the dryers can be performed by using conventional operations in the art, which are not particularly limited. The cryogenic separation device 15 can adopt a corresponding device known in the art, for example, can be a cold box, which is not particularly limited. For example, by the cryogenic separation device 15, the gas phase product is cooled from 40℃ to -152℃, so as to separate the by-product light components such as hydrogen, methane, ethane and ethylene from the carbon three, the by-product methane, ethane and ethylene and part of the hydrogen are used as fuel of the feed heating furnace 1, and the liquid phase carbon three product (mainly including propylene and unreacted propane, and possibly containing a small amount of residual by-product carbon four or more heavy components) enters a downstream separation unit to finally separate propylene product. The cryogenic separation device 15 can recover the latent heat of vaporization of the liquid phase propane and the cold energy of the high-pressure gas expansion output from the gas-liquid separation unit 300.

[0068] The second aspect of the present application also provides a process for carrying out the propane dehydrogenation reaction by using the propane dehydrogenation reaction system described above. The specific description of the system can be referred to the foregoing description, which will not be described one by one. The process specifically comprises the following steps:

[0069] (1) feeding the propane feed into the feed heating furnace 1, heating the propane feed by the heat provided by the combustion of the fuel in the feed heating furnace 1 to obtain heated propane feed and flue gas;

[0070] (2) feeding the flue gas into the heat recovery unit 100 to exchange heat with the water phase obtained from the wastewater treatment unit 500 to obtain cooled flue gas and preheated water phase; and carrying out gas-liquid separation on the cooled flue gas to obtain first gas phase and first liquid phase, wherein the first gas phase mainly comprises carbon dioxide and a small amount of water;

[0071] (3) the heated propane feed and the first gas phase are reacted in the presence of a catalyst in a reactor 5 of the reaction unit 200 to obtain a product stream comprising propylene, propane, hydrogen and carbon monoxide;

[0072] (4) the product stream and the first liquid phase are sent to a gas-liquid separation unit 300 for treatment to obtain a gas phase product, and an oily wastewater containing heavy hydrocarbons (specifically, by-produced heavy hydrocarbons of carbon four or more) and water is separated out;

[0073] The gas phase product is sent to a gas phase product post-treatment unit 400 for drying and cryogenic separation to obtain a liquid phase carbon three product and a by-produced light component; the by-produced light component is sent to the feed heating furnace 1 of step (1) for combustion as fuel;

[0074] (5) the oily wastewater is sent to a wastewater treatment unit 500 for treatment to obtain an aqueous phase and an oil phase, preferably, the oil content in the aqueous phase is below 0.1 mg / L; the aqueous phase is recycled to the heat recovery unit 100 of step (2) for heat exchange for subsequent steam generation; the oil phase is sent to the feed heating furnace 1 of step (1) for combustion as fuel.

[0075] In step (3), the heated propane feed and the first gas phase are reacted in the presence of a catalyst, wherein the carbon deposition is reduced by oxidation and water gas reaction, so that the catalyst performance can be maintained at a high level for a long time, and the propane partial pressure is reduced, which can improve the propane conversion rate, for example, by 3%, and increase the carbon monoxide and hydrogen, for example, by 13 t / h of carbon monoxide and 0.2 t / h of hydrogen.

[0076] In step (1), the propylene feed is heated to the required target temperature by the feed heating furnace 1 to reach the condition for contacting the catalyst in the reactor 5 to occur dehydrogenation reaction, for example, to about 590°C. Preferably, in step (1), the feed heating furnace 1 adopts forced ventilation oxygen-rich combustion mode, and the feed heating furnace 1 uses pure oxygen for combustion support, so as to reduce the energy waste caused by using air for combustion support, which causes part of the heat to be used to heat the nitrogen therein, and to reduce the generation of NOx. Specifically, the excess oxygen content in the feed heating furnace 1 is maintained at about 3%, and the heat is recovered by the convection section of the heating furnace for steam generation, for example, S40 steam 52 t / h can be generated, which can be used as the heat source of the separation unit; in some examples, the reaction raw material propane feed can be heated from 452°C to 590°C in the radiation section of the heating furnace. In the present application, the catalyst in the reactor can be a corresponding catalyst for propane dehydrogenation reaction in the art, for example, a non-noble metal supported catalyst well known in the art, wherein the non-noble metal is, for example, but not limited to, Zn, Cr, etc., which can be a commercially available corresponding catalyst or a corresponding catalyst prepared according to a method known in the art, which is not particularly limited.

[0077] Further, the method further comprises the step that: in step (2), the preheated water phase is sent into the convection section of the feed heating furnace to exchange heat with the flue gas, so that the preheated water phase is converted into steam.

[0078] Further, the method further comprises the step that: in step (2), the flue gas flows through the non-phase heat exchanger 2 and the phase heat exchanger 3 in the heat recovery unit 100 in sequence, and then enters the gas-liquid separation device 4 to be separated, so as to obtain the first gas phase and the first liquid phase. Specifically, in the phase heat exchanger 3, the flue gas exchanges heat with the water phase obtained in the wastewater treatment unit 500 to obtain a preliminarily preheated water phase; in the non-phase heat exchanger 2, the flue gas exchanges heat with the preliminarily preheated water phase to obtain a preheated water phase, which is then sent into the convection section of the feed heating furnace 1 to generate steam. In some examples, the flue gas side temperature of the non-phase heat exchanger 2 is reduced from 352℃ to 120℃, and the circulating water temperature is increased from 55℃ to 145℃; the flue gas side temperature of the phase heat exchanger 3 is reduced from 120℃ to 65℃, and the circulating water side temperature is increased from 25℃ to 55℃. Then the flue gas enters the gas-liquid separation device 4.

[0079] Further, the method further comprises the step that: in step (1), the propane feed for being sent into the feed heating furnace 1 is preheated by exchanging heat with the product stream output from the reactor 5 in the feed and product heat exchanger 6, so that the heat in the system is fully utilized. Preferably, the product stream after the heat exchange in the feed and product heat exchanger 6 is sent into the compressor feed cooler 7 to be cooled, and then sent into the gas-liquid separation unit 300 to be treated.

[0080] Further, the method further comprises the step that: in step (5), the oily wastewater is first sent into the demulsifier 16 of the wastewater treatment unit 500 to be demulsified, and then sent into the oil removal coalescer 17 of the wastewater treatment unit 500 to be separated into water phase and oil phase; the water phase is then sent into the heat recovery unit 100 to exchange heat, and then enters the feed heating furnace 1 to be further heated to generate steam; and the oil phase is sent into the feed heating furnace 1 as fuel to be burned. Specifically, in the demulsifier 16, the oil-in-water structure of the oily wastewater can be destroyed by adding a demulsifier, and then the oily wastewater enters the oil removal coalescer 17 to be separated into water phase and oil phase, for example, the oil content in the water phase is controlled to be below 0.1 mg / L. The demulsifier can be a corresponding agent commonly used in the art, and is not particularly limited. The separated water phase is preheated by the waste heat recovery unit 100 and then enters the feed heating furnace 1 to generate steam. The separated oil phase enters the feed heating furnace 1 as fuel.

[0081] The propane dehydrogenation reaction new process provided by the present application compared with prior art, the flue gas is heat recovered and gas-liquid separated to obtain the first gas phase containing carbon dioxide and a small amount of water, and the first liquid phase and the reaction product are gas-liquid separated to obtain the water phase containing oil wastewater which is further treated by wastewater treatment to obtain the water phase used for heat exchange in the system to produce steam, the by-product light component separated from the oil phase and the gas phase product is supplied to the feed heating furnace as fuel; the carbon dioxide and wastewater emissions can be reduced, and the reaction new process is green and low-carbon; secondly, by the partial oxidation of carbon dioxide and the water gas reaction of water, the high-carbon coking material generated by high-temperature cracking and olefin polymerization is converted into hydrogen and carbon monoxide, the atomic utilization rate is improved, and the energy and reaction time waste caused by catalyst regeneration can be avoided, and the present application does not need to additionally set a regeneration air heating furnace for catalyst regeneration; the present application can also effectively recover the flue gas heat, and further reduces the device energy consumption and production cost. The present application utilizes the oxidation of carbon dioxide in the flue gas and the water gas reaction to reduce the coking amount of the catalyst, prolong the reaction cycle, and improve the production capacity. At the same time, the heat of the flue gas is fully utilized to heat the wastewater, and the overall reaction energy consumption is reduced.

[0082] The present application will be further described by the following examples, but should not be understood as being limited to the present application.

[0083] In the examples, if the specific experimental steps or conditions are not specified, the corresponding conventional experimental steps can be operated or the conditions can be used. If the reagents or instruments used are not specified by the manufacturer, they are conventional products that can be obtained by purchase.

[0084] The catalyst used in the following example 1 and comparative example 1 is the same, which is a commercially available catalyst, Kelene Catofin 310 catalyst.

[0085] Example 1

[0086] The present example is carried out in the propane dehydrogenation reaction system shown in the formula (I), and the specific description of the system is described in the foregoing, which will not be described one by one. Figure 2 The propane dehydrogenation reaction is carried out in the propane dehydrogenation reaction system shown in the formula (I), and the specific description of the system is described in the foregoing, which will not be described one by one.

[0087] The specific operation process is as follows:

[0088] 1) The propane feed first exchanges heat with the product stream output from the reactor 5 in the inlet and outlet material heat exchanger 6, and then the propane feed enters the radiant section of the feed heating furnace 1, and the heat generated by the fuel combustion in the feed heating furnace heats the propane feed from 452 DEG C to 590 DEG C, thereby obtaining the heated propane feed and generating flue gas;

[0089] The fuel used in the feed heating furnace 1 is the by-product light components separated from the gas phase product post-treatment unit 400 and the oil phase separated from the wastewater treatment unit 500; specifically, the by-product light components mainly include methane, ethane, ethylene and hydrogen, and the specific composition is hydrogen 35.8%, methane 29.6%, ethane 20.2%, propane 1.0%, butane 1.0%, nitrogen 0.3%, carbon monoxide 10.1%, carbon dioxide 2.0%, molar percentage, and the flow rate is 4.05 t / h; the composition of the oil phase is mainly C8-C20 aromatic hydrocarbons, and the flow rate is about 22 kg / h. The feed heating furnace 1 adopts a forced ventilation oxygen-rich combustion mode and uses pure oxygen for combustion. The flow rate of pure oxygen used is 13.4 t / h. The excess oxygen content is maintained at 3%, and the flue gas composition is mainly water 63.2%, oxygen 3% and carbon dioxide 33.8%, molar percentage; the exhaust gas temperature after heat recovery of the flue gas through the convection section of the feed heating furnace 1 is 308°C. The convection section of the feed heating furnace 1 is used for steam production, specifically, the preheated water phase output by the heat recovery unit 100 is further heated by the flue gas flowing through the convection section and converted into steam, which can produce S40 steam 52 t / h. The steam can be used as a heat source for the downstream separation unit.

[0090] 2) The flue gas discharged from the feed heating furnace 1 is sent into the heat recovery unit 100 through the flue gas discharge pipe 20 for waste heat recovery, and the flue gas sequentially flows through the non-phase heat exchanger 2 and the phase heat exchanger 3 in the heat recovery unit 100, and then enters the gas-liquid separation device 4 for gas-liquid separation; specifically, in the phase heat exchanger 3, the flue gas exchanges heat with the water phase (or called circulating water) obtained from the wastewater treatment unit 500 to obtain a preliminarily preheated water phase; in the non-phase heat exchanger 2, the flue gas exchanges heat with the preliminarily preheated water phase to obtain a preheated water phase. The non-phase heat exchanger 2 is used to fully recover the heat of the flue gas while avoiding the problem of dew point corrosion caused by water liquefaction, which can reduce the material grade of the heat exchanger to reduce investment. The phase heat exchanger 3 is used to fully recover the phase change heat of water vapor in the flue gas, and the water liquefaction process removes the oxides of nitrogen and sulfur in the flue gas to avoid corrosion of the subsequent reactor 5. The temperature of the flue gas on the non-phase heat exchanger 2 side decreases from 308°C to 130°C, and the temperature of the circulating water increases from 109°C to 127°C. The temperature of the flue gas on the phase heat exchanger 3 side decreases from 130°C to 35°C, and the temperature of the circulating water side increases from 25°C to 109°C. Then the flue gas enters the gas-liquid separation device 4, and the first gas phase and the first liquid phase are obtained after gas-liquid separation; wherein the main components of the first gas phase are 5.5% water, 7.7% oxygen and 86.7% carbon dioxide, molar percentage.

[0091] 3) The heated propane feed obtained from the feed heater 1 and the first gas phase obtained from the gas-liquid separation device 4 of the heat recovery unit 100 are fed into the reactor 5 of the reaction unit 200 as reactor feed. The composition of the heated propane feed and the first gas phase mixture is mainly 0.9% ethane, 0.9% propylene, 94.0% propane, 0.6% butane, 0.2% water, 0.2% oxygen, and 3.2% carbon dioxide, molar percentage. The flow rate is 305 t / h. The reaction occurs in reactor 5, with the inlet temperature of reactor 5 controlled at 590℃ and the pressure at -50 kPa. The outlet temperature of reactor 5 is 565℃. The main components of the reaction products in the product stream are 32.6% hydrogen, 1.2% methane, 1.4% ethane, 0.2% ethylene, 32.9% propane, 25.4% propylene, 0.3% nitrogen, 5.3% carbon monoxide, 0.1% carbon dioxide, and 0.6% C4 and above heavy hydrocarbons, molar percentage. After the product stream is collected, it exchanges heat with the propane feed in the inlet / outlet heat exchanger 6 before entering the gas-liquid separation unit 300. The temperature of the propane feed is increased from 25°C to 452°C, while the temperature of the product stream is decreased from 565°C to 142°C. Simultaneously, to prevent the inner wall of reactor 5 from affecting the reaction, 3 kg / h of dimethyl disulfide is added for metal passivation.

[0092] 4) The product stream after heat exchange in the heat exchanger 6 is sent to the compressor feed cooler 7 to be cooled to 40°C. Then, it enters the gas-liquid separation unit 300 with the first liquid phase obtained from the gas-liquid separation device 4 of the heat recovery unit 100 for the separation of heavy hydrocarbons and water. Specifically, as shown... Figure 2 As shown, after heavy hydrocarbons and water are separated from the gaseous products in the primary gas-liquid separator 8, they enter the compressor 9. After primary compression, the pressure of the gaseous products increases from -50 kPa to 0.6 MPa. The gaseous products then enter the interstage cooler 10, where the temperature decreases from 162°C to 40°C. The gaseous products then enter the secondary gas-liquid separator 11 for further gas-liquid separation, from which heavy hydrocarbons and water are separated. After secondary compression in the compressor 9, the pressure of the gaseous products is further increased to 1.2 MPa. They then pass through the interstage cooler 10 for further cooling, where the temperature decreases from 154°C to 40°C. Finally, they enter the tertiary gas-liquid separator 13 for further separation of heavy hydrocarbons and water. The heavy hydrocarbons and water separated in each gas-liquid separator are discharged as emulsified oily wastewater into the wastewater treatment unit 500, with a total oily wastewater volume of 5.2 t / h. The gaseous product collected from the three-stage gas-liquid separator 13 enters the gaseous product post-processing unit 400.

[0093] In the gas phase product post-treatment unit 400, the gas phase product obtained from the gas-liquid separation unit 300 is first sent to the drying device 14 for drying, and the water and hydrogen sulfide contents in the dried gas phase product are less than 1 ppm respectively; then the gas phase product is sent to the cryogenic separation device 15, and the temperature of the gas phase product is reduced from 40°C to -152°C, so that the by-produced hydrogen, methane and other carbon-containing components can be separated. The by-produced methane, ethane, ethylene and part of the hydrogen (i.e. the by-produced light components) enter the gas phase stream, and the by-produced light components are sent to the feed heating furnace 1 for use as the fuel of the furnace; the liquid phase carbon three product (mainly propane 53.0%, propylene 41.0%, hydrogen 0.1%, methane 1.3%, ethane 2.3%, ethylene 0.3%, carbon monoxide 0.8%, carbon dioxide 0.2%, carbon four heavy hydrocarbon 1.0% and the like, molar percentage) enters the downstream separation unit to finally separate the propylene product.

[0094] 5) The oil-containing wastewater obtained from the gas-liquid separation unit 300 is sent to the wastewater treatment unit 500 for treatment. Specifically, the oil-containing wastewater is first sent to the demulsifier 16, and the oil-in-water structure of the oil-containing wastewater is destroyed by adding a demulsifier (cationic organic demulsifier SM535, dosage 1000 mg / L); then the oil-containing wastewater is sent to the oil removal coalescer 17, and the small oil droplets are continuously coalesced into large oil droplets, which are then separated from water, and the oil content in the water phase is less than 0.1 mg / L. The separated water phase is subjected to heat exchange in the heat recovery unit 100 in step 2), and finally enters the convection section of the feed heating furnace 1 to generate steam. The separated oil phase enters the feed heating furnace 1 as fuel.

[0095] Comparative Example 1

[0096] The comparative example adopts the propane dehydrogenation reaction system shown in Figure 3 , Figure 4 to carry out propane dehydrogenation reaction, Figure 4 the system and the system shown in Figure 2 The main differences between the system and the system shown in the present application include: a regeneration unit 600 is additionally provided, which is mainly used for removing the carbon deposited on the catalyst during the reaction to restore the activity of the catalyst to the initial level; no heat recovery unit and wastewater treatment unit are provided. The same catalyst as in the reactor 5 of Example 1 is used in the reactor 5 of the comparative example.

[0097] The specific operation process is as follows:

[0098] 1) The propane feed is first subjected to heat exchange with the product stream output from the reactor 5 in the feed and product heat exchanger 6, and then the propane feed enters the radiant section of the feed heating furnace 1, and the temperature of the propane feed is raised from 452°C to 590°C by the heat generated by the combustion of the fuel in the feed heating furnace, thereby obtaining the heated propane feed and generating flue gas;

[0099] The fuel used in the feed heating furnace is a by-product light component, the specific composition is mainly hydrogen 35.8%, methane 29.6%, ethane 20.2%, propane 1.0%, butane 1.0%, nitrogen 0.3%, carbon monoxide 10.1%, carbon dioxide 2.0%, molar percentage, the flow rate is 4.05 t / h. The feed heating furnace 1 uses natural ventilation mode, the flow rate of air used is 57.6 t / h. The excess oxygen content is maintained at 3%, and the flue gas composition is mainly water 18.4%, oxygen 0.6%, carbon dioxide 10%, nitrogen 71.0%, molar percentage. The flue gas temperature after recovering heat in the convection section is 308℃, the convection section of the feed heating furnace 1 is used for steam production, which can produce S40 steam 47 t / h, and the steam is used as the heat source for the downstream separation unit. The radiant section of the feed heating furnace 1 is used to heat the reaction raw material from 452℃ to 590℃. The flue gas heat of the feed heating furnace 1 is recovered by a non-phase change heat exchanger 2, which is used to preheat the air to 300℃, and the flue gas temperature is reduced to 130℃. The air preheated by the non-phase change heat exchanger 2 enters the feed heating furnace 1.

[0100] 2) The reactor 5 feed is the propane raw material heated by the feed heating furnace 1. The raw material composition is ethane 0.9%, propylene 0.6%, propane 97.6%, butane 0.9%, molar percentage. The flow rate is 294 t / h. After entering the reactor 5, the reaction is controlled, the reactor 5 inlet temperature is 590℃, and the pressure is -50 kPa. The reactor 5 outlet temperature is 565℃, and the reaction product in the product stream is mainly composed of hydrogen 31.5%, methane 1.3%, ethane 1.5%, ethylene 0.2%, propane 36.3%, propylene 27.1%, nitrogen 0.3%, carbon monoxide 1.0%, carbon dioxide 0.1%, carbon four or more heavy hydrocarbons 0.7%, molar percentage. After the product stream is extracted, the propane feed is heated from 25℃ to 452℃, and the product stream temperature is reduced from 565℃ to 142℃ after exchanging heat with the propane feed in the feed and product heat exchanger 6; then the product stream flows through the compressor feed cooler 7 to reduce the temperature to 40℃, and then enters the gas-liquid separation unit 300. At the same time, in order to prevent the reactor 5 inner wall from affecting the reaction, 3 kg / h of dimethyl disulfide is added for metal passivation.

[0101] 3) The process of treating the product stream in the gas-liquid separation unit 300 is the same as that of Example 1, which will not be repeated. The difference is that in Comparative Example 1, the oil-containing wastewater separated in the gas-liquid separation unit is directly discharged for treatment.

[0102] The gaseous phase product treated by the gas-liquid separation unit 300 is sent to the drying device 14 and the cryogenic separation device 15 of the gaseous phase product post-treatment unit 400 for treatment, and the process is the same as that of Example 1, which will not be repeated.

[0103] 4) The catalyst in reactor 5 of step 2) is regenerated once after about nine minutes of use, and the time for one regeneration is about nine minutes. Specifically, the regeneration of the catalyst is performed in a regeneration unit 600 by reacting air with the carbon deposited on the catalyst to remove the carbon deposit. The regeneration unit 600 specifically includes a regeneration air heating furnace 18 and a regeneration reactor 19. Specifically, the hot air required by the regeneration reactor 19 is heated to 610°C by the regeneration air heating furnace 18, and the fuel gas used by the regeneration air heating furnace 18 is mainly composed of hydrogen 23.8%, methane 53.2%, ethane 13.4%, propane 0.7%, butane 0.7%, nitrogen 0.2%, carbon monoxide 6.7%, and carbon dioxide 1.3% in terms of molar percentage, and the flow rate is 6.05 t / h. The regeneration air heating furnace 18 uses a natural draft mode. The flow rate of the air used is 57.6 t / h. The excess oxygen content is maintained at 3%, and the flue gas composition of the regeneration air heating furnace 18 is mainly composed of water 18.4%, oxygen 0.6%, carbon dioxide 10%, and nitrogen 71% in terms of molar percentage. The flue gas of the regeneration air heating furnace 18 is mixed with the flue gas of the feed heating furnace 1 and then discharged to the atmosphere. The air heated by the regeneration air heating furnace enters the regeneration reactor 20 and reacts with the carbon deposited on the catalyst to remove the carbon deposit, thereby obtaining the regenerated catalyst.

[0104] From the perspective of emission reduction, example 1 can basically achieve zero emission of carbon dioxide, and all the carbon is converted into carbon monoxide products for delivery. Comparative example 1 needs to discharge 24.9 t / h of carbon dioxide. At the same time, 5.2 t / h of oil-containing wastewater needs to be discharged, and the annual wastewater treatment cost is 1.2 million yuan based on the downstream treatment cost of 30 yuan per ton of wastewater.

[0105] From the perspective of energy saving, example 1 can additionally recover 7.9 MW of flue gas heat through the phase change heat exchanger 3 of the heat recovery unit 100, and the heavy hydrocarbons recovered by the wastewater treatment unit can replace 0.02 t / h of fuel gas with the same heat value. Since the reaction process does not need to additionally set up a regeneration unit 600 for catalyst regeneration, the heating energy consumption of the regeneration air can be saved, that is, about 6 t / h of fuel gas.

[0106] From the perspective of reaction, the first gas phase containing carbon dioxide and water is added to the feed of reactor 5 in example 1, and the carbon deposition is reduced through oxidation and water gas reaction, so that the catalyst performance can be maintained at a high level for a long time, the propane partial pressure is reduced, the propane conversion rate can be increased by 3%, and 13 t / h of carbon monoxide and 0.2 t / h of hydrogen can be increased. The catalyst in example 1 above can be continuously and stably operated for four years; the catalyst in comparative example 1 needs to be frequently regenerated, and each regeneration will cause a certain degree of attenuation of the catalyst activity. The overall life of the catalyst in comparative example 1 is reduced to three years, and a large amount of time and heat is consumed in the regeneration process.

[0107] It is readily understood that the above-described embodiments are only illustrative of the application and not intended to limit the scope of the application. Other variations and modifications can be made to the embodiments described and illustrated herein, without departing from the spirit of the application, the scope of which is defined by the appended claims.

Claims

1. A propane dehydrogenation reaction system characterized by, The system comprises a feed heating furnace, a heat recovery unit, a reaction unit, a gas-liquid separation unit, a wastewater treatment unit, a gas phase product post-treatment unit; The feed heating furnace is used for heating the propane feed by burning fuel to obtain heated propane feed and flue gas; The heat recovery unit is used for heat exchanging the flue gas with the water phase obtained in the wastewater treatment unit to obtain cooled flue gas and preheated water phase, and gas-liquid separation of the cooled flue gas to obtain first gas phase and first liquid phase; The reaction unit comprises a reactor, which is used for reacting the heated propane feed and the first gas phase in the presence of a catalyst to obtain a product stream comprising propylene, propane, hydrogen and carbon monoxide; The gas-liquid separation unit is used for processing the product stream and the first liquid phase to obtain a gas phase product, and to obtain oil-containing wastewater comprising heavy hydrocarbon and water; The wastewater treatment unit is used for processing the oil-containing wastewater to obtain a water phase and an oil phase; The gas phase product post-treatment unit is used for drying and cryogenic separation of the gas phase product to obtain a liquid phase carbon three product and a by-product light component; The gas phase product post-treatment unit and the wastewater treatment unit are respectively connected with the feed heating furnace, and the by-product light component and the oil phase are sent into the feed heating furnace as the fuel.

2. The propane dehydrogenation reaction system of claim 1, wherein, The heat recovery unit is connected with a convection section of the feed heating furnace to heat exchange the preheated water phase with the flue gas flowing through the convection section to obtain steam.

3. The propane dehydrogenation reaction system according to claim 1, wherein The flue gas outlet of the feed heating furnace is connected with a flue gas discharge pipe; The heat recovery unit comprises a non-phase change heat exchanger, a phase change heat exchanger and a gas-liquid separation device; and along the flow direction of the flue gas in the flue gas discharge pipe, the non-phase change heat exchanger, the phase change heat exchanger and the gas-liquid separation device are connected in series through the flue gas discharge pipe; The wastewater treatment unit is connected with a water phase conveying pipe for outputting the water phase, and the water phase conveying pipe is connected with the phase change heat exchanger to heat exchange the water phase with the flue gas flowing through the phase change heat exchanger to obtain a preliminary preheated water phase; The non-phase change heat exchanger is further connected with a water phase outlet of the phase change heat exchanger through a preliminary preheated water phase output pipeline to heat exchange the preliminary preheated water phase with the flue gas flowing through the non-phase change heat exchanger to obtain the preheated water phase; The gas-liquid separation device is used for gas-liquid separation of the flue gas output by the phase change heat exchanger to obtain the first gas phase and the first liquid phase.

4. The propane dehydrogenation reaction system of any one of claims 1-3, wherein, The reaction unit further comprises an inlet and outlet material heat exchanger for heat exchanging the product stream before entering the gas-liquid separation unit with the propane feed before entering the feed heating furnace.

5. The propane dehydrogenation reaction system of claim 4, wherein, The reaction unit further comprises a compressor feed cooler, which is arranged between the inlet and outlet material heat exchanger and the gas-liquid separation unit, and is used for cooling the product stream output by the inlet and outlet material heat exchanger before entering the gas-liquid separation unit.

6. The propane dehydrogenation reaction system of any one of claims 1-3, wherein, The gas-liquid separation unit comprises multiple-stage gas-liquid separation tanks connected in series, and between two adjacent stages, a compressor and an inter-stage cooler are connected in series between the gas phase outlet of the upstream gas-liquid separation tank and the material inlet of the downstream gas-liquid separation tank.

7. The propane dehydrogenation reaction system of any one of claims 1-3, wherein, The wastewater treatment unit comprises a demulsifier and an oil removal coalescer; The demulsifier is used to break the oil-in-water structure of the oily wastewater; The oil removal coalescer is used to treat the material after the demulsifier treatment, and separate the water phase and the oil phase.

8. The propane dehydrogenation reaction system of any one of claims 1-3, wherein, The gas phase product post-treatment unit comprises a drying device and a cryogenic separation device; The drying device is used to dry the gas phase product to remove water and hydrogen sulfide entrained in the gas phase product; The cryogenic separation device is used to cryogenically separate the gas phase product after the drying device treatment to obtain a liquid phase carbon three product and the by-product light component.

9. A process for dehydrogenating propane using the propane dehydrogenation reaction system according to any one of claims 1 to 8, characterized by, The method comprises the following steps: (1) feeding the propane into the feed heating furnace, heating the propane by the heat provided by the combustion of fuel in the feed heating furnace to obtain heated propane and flue gas; (2) feeding the flue gas into the heat recovery unit to exchange heat with the water phase obtained in the wastewater treatment unit to obtain cooled flue gas and preheated water phase; and performing gas-liquid separation on the cooled flue gas to obtain a first gas phase and a first liquid phase; (3) reacting the heated propane and the first gas phase in the presence of a catalyst in the reactor of the reaction unit to obtain a product stream comprising propylene, propane, hydrogen and carbon monoxide; (4) feeding the product stream and the first liquid phase into the gas-liquid separation unit for treatment to obtain a gas phase product, and separating an oily wastewater comprising heavy hydrocarbons and water; feeding the gas phase product into the gas phase product post-treatment unit for drying and cryogenic separation to obtain a liquid phase carbon three product and a by-product light component; and feeding the by-product light component into the feed heating furnace of step (1) as fuel for combustion; (5) feeding the oily wastewater into the wastewater treatment unit for treatment to obtain a water phase and an oil phase; recycling the water phase to the heat recovery unit of step (2) for heat exchange; and feeding the oil phase into the feed heating furnace of step (1) as fuel for combustion.

10. The process of claim 9, wherein, The feed heating furnace uses pure oxygen for combustion support.

11. The process of claim 9, wherein, The method further comprises the following steps: In step (2), the preheated water phase is fed into the convection section of the feed heating furnace to exchange heat with the flue gas, so that the preheated water phase is converted into steam; and / or, in step (2), in the heat recovery unit, the flue gas flows through a non-phase heat exchanger and a phase heat exchanger in sequence, and then enters a gas-liquid separation device to perform gas-liquid separation to obtain the first gas phase and the first liquid phase; in the phase heat exchanger, the flue gas exchanges heat with the water phase obtained in the wastewater treatment unit to obtain a preliminarily preheated water phase; in the non-phase heat exchanger, the flue gas exchanges heat with the preliminarily preheated water phase to obtain the preheated water phase.

12. The process of claim 9, wherein, The method further comprises the following steps: In step (1), the propane feed for feeding into the feed heating furnace is pre-exchanged with the product stream output from the reactor in an in-out material heat exchanger; And / or, in step (5), the oily wastewater is first sent into a demulsifier of the wastewater treatment unit for demulsification, and then sent into an oil removal coalescer of the wastewater treatment unit for oil-water separation, to obtain the water phase and the oil phase.

13. The process of claim 12, wherein, In step (1), the product stream after heat exchange in the in-out material heat exchanger is sent into a compressor feed cooler for cooling, and then sent into the gas-liquid separation unit.

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