System for producing vinyl chloride through oxychlorination

Abstract

The utility model provides a system for producing vinyl chloride through oxychlorination, and belongs to the field of vinyl chloride synthesis. According to the system for producing vinyl chloride through oxychlorination, dichloroethane is prepared through the oxychlorination reaction unit, then the dichloroethane is refined through the refining unit, then the refined dichloroethane is cracked in the cracking unit to prepare vinyl chloride, and finally the vinyl chloride is obtained through purification in the vinyl chloride refining unit. Dichloroethane is prepared through a direct chlorination reaction unit, so that the yield of dichloroethane is increased, and a raw material is provided for cracking of dichloroethane; according to the system for producing vinyl chloride through oxychlorination, dichloroethane is prepared through the oxychlorination reaction unit and the direct chlorination unit, so that the working efficiency of the system is improved.

Description

Technical Field

[0001] The utility model relates to the field of vinyl chloride synthesis, in particular to a system for producing vinyl chloride by oxychlorination. Background Art

[0002] Vinyl chloride is an important chemical raw material and a common organic compound. Its chemical formula is C2H3C1. It is a colorless gas with a pungent odor. Vinyl chloride is widely used in industry to prepare polyvinyl chloride (PVC) resins, and is also used as a solvent and chemical intermediate. The structure of vinyl chloride is simple and clear. It is an important organic synthetic raw material. It can be used to prepare a variety of organic compounds, such as polyvinyl chloride, allyl chloride, chloroprene, etc. Among them, polyvinyl chloride is the most important derivative of vinyl chloride and is widely used in building materials, packaging materials, electrical insulation materials and other fields.

[0003] According to the different raw materials, the production methods of vinyl chloride monomer are mainly divided into five types: ethylene method and acetylene method, combined method, olefin method, ethylene oxychlorination method, and ethane one-step oxychlorination method. At present, the acetylene method and ethylene oxychlorination method are commonly used. Among them, the main raw materials of the acetylene method come from limestone and coal, and the synthetic vinyl chloride process uses mercuric chloride as a catalyst.

[0004] CN108373400B discloses an acetylene-based vinyl chloride synthesis process, comprising: acetylene is mixed with hydrogen chloride in a primary mixer in proportion through an acetylene flame arrester; the mixed gas accounting for 20-90% of the volume ratio of the mixed gas is preheated through a primary preheater, and then enters a front converter to synthesize vinyl chloride; the mixed gas accounting for 80-10% of the volume ratio of the gas is preheated through a secondary preheater, and then mixed with the mixed gas from the front converter in a secondary mixer; the gas after the secondary mixing enters a rear converter, and vinyl chloride is synthesized again to react to generate crude vinyl chloride, and the mixed gas enters a post-processing system. The catalyst of the front and rear converters of the process catalyst does not need to be pumped out, which improves the equipment operation rate, reduces the production cost, and at the same time reduces the loss of the catalyst caused by pumping out and protects the environment; the mixed gas is introduced into the rear converter, the system pressure increases, and the conversion of acetylene is promoted, which is beneficial for the synthesis of vinyl chloride.

[0005] However, due to the toxicity of mercuric chloride and its harmfulness to the environment, the petroleum ethylene process has become the first choice for the current polyvinyl chloride industry. As an important petrochemical raw material, ethylene needs to go through multiple steps of refining, purification, and cracking during the production process. The energy consumed in the process of preparing vinyl chloride is extremely high, so it is necessary to select efficient and energy-saving production equipment to reduce the energy consumption of ethylene production.

[0006] In summary, mercuric chloride used in the acetylene method commonly used in the synthesis of vinyl chloride is toxic, so the ethylene oxychlorination method has been developed. However, the ethylene oxychlorination method requires high energy consumption in the process of preparing vinyl chloride, and the large energy loss in the synthesis process has become a problem that needs to be solved urgently. Utility Model Content

[0007] In view of the above problems, the utility model provides a system for producing vinyl chloride by oxychlorination, which simultaneously prepares vinyl chloride by the oxychlorination system and the ethylene chlorination system, thereby improving the efficiency of vinyl chloride synthesis and reusing the energy and raw materials lost in the system.

[0008] The utility model provides a system for producing vinyl chloride by oxychlorination. According to the flow direction of materials, the system sequentially comprises an oxychlorination reaction unit, a dichloroethane refining unit, a direct chlorination unit, a cracking unit and a vinyl chloride refining unit;

[0009] The oxychlorination reaction unit is connected to the ethylene dichloride refining unit and the vinyl chloride refining unit respectively;

[0010] The ethylene dichloride refining unit is also connected to the direct chlorination unit and the cracking unit respectively;

[0011] The cracking unit is also connected to a vinyl chloride refining unit;

[0012] The vinyl chloride refining units are also respectively connected to the oxychlorination reaction units;

[0013] The system also includes an incineration unit and a waste liquid treatment unit.

[0014] Furthermore, the oxychlorination reaction unit includes a hydrogenation reactor, an oxychlorination reactor, an oxychlorination hot quenching tower, a carbon dioxide stripping tower, a separation tank, an alkali washing tank and an ethylene dichloride storage tank.

[0015] Furthermore, the ethylene dichloride refining unit includes a lightness removal tower, a high boiling tower, a vacuum tower and an ethylene dichloride product tank.

[0016] Further, the direct chlorination unit comprises a direct chlorination reactor.

[0017] Furthermore, the cracking unit includes a cracking furnace and a cracking quenching washing tower.

[0018] Furthermore, the vinyl chloride refining unit includes a hydrogen chloride tower, a vinyl chloride tower, a chlorination reactor, a vinyl chloride stripping tower and a vinyl chloride storage tank.

[0019] Further, the hydrogenation reactor is provided with a hydrogen chloride inlet and a hydrogen chloride outlet;

[0020] The hydrogen chloride inlet of the hydrogenation reactor is connected to the hydrogen chloride tower;

[0021] The hydrogen chloride outlet of the hydrogenation reactor is connected to the oxychlorination reactor;

[0022] The hydrogenation reactor is also provided with a hydrogen inlet.

[0023] Furthermore, a material outlet is provided above the oxychlorination reactor, and the oxychlorination reactor is also provided with a hydrogen chloride inlet, an oxygen inlet, an ethylene inlet, a circulating inlet, a heat carrier inlet and a heat carrier outlet;

[0024] The material outlet of the oxychlorination reactor is connected to the oxychlorination hot quenching tower;

[0025] The hydrogen chloride inlet of the oxychlorination reactor is connected to the hydrogen chloride outlet of the hydrogenation reactor through a gas pipeline;

[0026] The circulating air inlet of the oxychlorination reactor is connected to the oxychlorination hot quenching tower;

[0027] The oxychlorination reactor discharges and enters heat through a heat carrier inlet and a heat carrier outlet.

[0028] Furthermore, a circulating gas outlet and a waste gas outlet are provided at the top of the oxychlorination heat quenching tower, and the oxychlorination heat quenching tower is also provided with a material inlet, a water inlet and a material outlet;

[0029] The circulating gas outlet of the oxychlorination heat quenching tower is connected to the circulating gas inlet of the oxychlorination reactor through a gas pipeline;

[0030] The exhaust gas outlet of the oxychlorination heat quenching tower is connected to the incineration unit through a gas pipeline;

[0031] The material inlet of the oxychlorination heat quenching tower is connected to the material outlet of the oxychlorination reactor through a gas pipeline;

[0032] The water inlet of the oxychlorination heat quenching tower is connected to the separation tank;

[0033] The material outlet of the oxychlorination heat quenching tower is connected to the carbon dioxide stripping tower.

[0034] Furthermore, a spray device is provided on the top of the oxychlorination heat quenching tower, and the spray device of the oxychlorination heat quenching tower is provided with cooling water by the water inlet of the oxychlorination heat quenching tower, and the cooling water is sprayed from top to bottom in the oxychlorination heat quenching tower.

[0035] Furthermore, the circulating gas outlet and the waste gas outlet of the oxychlorination hot quenching tower discharge gas to the oxychlorination reactor and the incineration unit at the same time to maintain the system balance.

[0036] Furthermore, the carbon dioxide stripping tower is provided with a material inlet, a nitrogen inlet and a material outlet;

[0037] The material inlet of the carbon dioxide stripping tower is connected to the material outlet of the oxychlorination thermal quenching tower through a liquid pipeline;

[0038] The material outlet of the carbon dioxide stripping tower is connected to the separation tank;

[0039] The carbon dioxide stripping tower is also provided with a nitrogen inlet;

[0040] The material outlet of the carbon dioxide stripping tower is arranged below the carbon dioxide stripping tower.

[0041] Furthermore, the separation tank is provided with a material inlet, a water outlet and a material outlet;

[0042] The material inlet of the separation tank is connected to the material outlet of the carbon dioxide stripping tower through a liquid pipeline;

[0043] The water outlet of the separation tank is connected to the water inlet of the oxychlorination heat quenching tower through a liquid pipeline;

[0044] The material outlet of the separation tank is connected to the alkali washing tank;

[0045] The water outlet of the separation tank is arranged at the bottom of the separation tank, and the material outlet of the separation tank is arranged at the side.

[0046] Furthermore, the alkali washing tank is provided with a material inlet, a material outlet and a waste liquid outlet;

[0047] The material inlet of the alkali washing tank is connected to the material outlet of the separation tank through a liquid pipeline;

[0048] The material outlet of the alkali washing tank is connected to the ethylene dichloride storage tank;

[0049] The waste liquid outlet of the alkali washing tank is connected to the waste liquid treatment unit through a liquid pipeline;

[0050] The waste liquid outlet of the alkali washing tank is arranged at the bottom of the alkali washing tank.

[0051] Furthermore, an alkaline liquid is passed through the alkaline washing tank to wash the product in the alkaline washing tank.

[0052] Furthermore, the ethylene dichloride storage tank is provided with a material inlet and a material outlet;

[0053] The material inlet of the dichloroethane storage tank is connected to the material outlet of the alkali washing tank through a liquid pipeline;

[0054] The material outlet of the ethylene dichloride storage tank is connected to the lightness removal tower.

[0055] Furthermore, the lightness removal tower is provided with a material inlet, a material outlet and an exhaust gas outlet;

[0056] The material inlet of the lightness removal tower is connected to the material outlet of the ethylene dichloride storage tank through a liquid pipeline;

[0057] The material outlet of the lightness removal tower is connected to the high boiling tower through a liquid pipeline;

[0058] The exhaust gas outlet of the light-removal tower is connected to the incineration unit and the waste liquid treatment unit through a pipeline;

[0059] A condenser is provided on the pipeline connecting the exhaust gas outlet of the light-removal tower with the incineration unit and the waste liquid treatment unit;

[0060] The material outlet of the lightness removal tower is arranged below the lightness removal tower, and the exhaust gas outlet of the lightness removal tower is arranged at the top of the lightness removal tower.

[0061] Furthermore, the high boiling tower is provided with a liquid material inlet, a circulating material inlet, a gas material inlet, a material outlet and a circulating liquid inlet;

[0062] The liquid material inlet of the high boiling tower is connected to the material outlet of the light removal tower through a liquid pipeline;

[0063] The circulating material inlet of the high boiling tower is also connected to the chlorination reactor through a liquid pipeline;

[0064] The circulating liquid port of the high boiling tower is connected to the direct chlorination reactor;

[0065] The gas material inlet of the high boiling tower is connected to the direct chlorination reactor;

[0066] The material outlet of the high boiling tower is connected to the ethylene dichloride product tank;

[0067] The material outlet of the high boiling tower is arranged at the top of the high boiling tower, and the circulating liquid inlet of the high boiling tower is arranged below the high boiling tower.

[0068] Furthermore, the vacuum tower is provided with a material inlet, a material outlet and an impurity outlet;

[0069] The material inlet of the vacuum tower is connected to the cracking quenching washing tower;

[0070] The material outlet of the vacuum tower is connected to the ethylene dichloride product tank;

[0071] The impurity port of the vacuum tower is connected to the incineration unit;

[0072] The material outlet of the vacuum tower is arranged at the top of the vacuum tower, and the impurity outlet of the vacuum tower is arranged at the bottom of the vacuum tower.

[0073] Furthermore, the ethylene dichloride product tank is provided with a material inlet and a material outlet;

[0074] The material inlet of the ethylene dichloride product tank is connected to the material outlet of the high boiling tower through a pipeline;

[0075] The dichloroethane product tank is also connected to the material outlet of the vacuum tower through a pipeline;

[0076] The material outlet of the ethylene dichloride product tank is connected to the cracking furnace;

[0077] A condenser is provided on the pipeline connecting the material inlet of the dichloroethane product tank with the high boiling tower and the vacuum tower, and the vapor material is converted into liquid through the condenser;

[0078] The material outlet of the ethylene dichloride product tank is arranged below the ethylene dichloride product tank.

[0079] Furthermore, the direct chlorination reactor is provided with an ethylene gas inlet, a chlorine gas inlet, a material outlet and a circulating liquid inlet;

[0080] The material outlet of the direct chlorination reactor is connected to the gas material inlet of the high boiling tower through a gas pipeline;

[0081] The circulating liquid inlet of the direct chlorination reactor is connected to the circulating liquid inlet of the high boiling tower through a liquid pipeline;

[0082] The material outlet of the direct chlorination reactor is arranged above the direct chlorination reactor.

[0083] Furthermore, the cracking furnace is provided with a material inlet and a material outlet;

[0084] The material inlet of the cracking furnace is connected to the material outlet of the ethylene dichloride product tank through a liquid pipeline;

[0085] The material outlet of the cracking furnace is connected to the cracking quenching washing tower.

[0086] Furthermore, the cracking quenching washing tower is provided with a material inlet, a gas material outlet, a liquid material outlet and an impurity outlet;

[0087] The material inlet of the cracking quenching washing tower is connected to the material outlet of the cracking furnace through a liquid pipeline;

[0088] The gas material outlet of the cracking quenching washing tower is connected to the hydrogen chloride tower;

[0089] The liquid material outlet of the cracking quenching washing tower is connected to the hydrogen chloride tower;

[0090] The impurity outlet of the cracking quenching washing tower is connected to the material inlet of the vacuum tower through a liquid pipeline;

[0091] The gas material outlet of the cracking quenching washing tower is arranged at the top of the cracking quenching washing tower, and the impurity outlet of the cracking quenching washing tower is arranged below the cracking quenching washing tower.

[0092] Furthermore, a condenser is provided above the cracking quenching washing tower to condense and reflux the product in the cracking quenching washing tower.

[0093] Furthermore, the hydrogen chloride tower is provided with a hydrogen chloride gas outlet, a material inlet, a circulating gas inlet and a material outlet;

[0094] The hydrogen chloride gas outlet of the hydrogen chloride tower is connected to the hydrogen chloride gas inlet of the hydrogenation reactor through a gas pipeline;

[0095] The material inlet of the hydrogen chloride tower is connected to the liquid material outlet of the cracking quenching washing tower through a liquid pipeline;

[0096] The material inlet of the hydrogen chloride tower is also connected to the gas material outlet of the cracking quenching washing tower through a pipeline;

[0097] A condenser is installed on the pipeline connecting the material inlet of the hydrogen chloride tower and the gas material outlet of the cracking quenching washing tower, and the gaseous material becomes liquid after passing through the condenser;

[0098] The circulating gas port of the hydrogen chloride tower is connected to the vinyl chloride stripping tower;

[0099] The material outlet of the hydrogen chloride tower is connected to the vinyl chloride tower;

[0100] The hydrogen chloride gas outlet of the hydrogen chloride tower is arranged at the top of the hydrogen chloride tower, and the material outlet of the hydrogen chloride tower is arranged below the hydrogen chloride tower.

[0101] Furthermore, the vinyl chloride tower is provided with a material inlet, a material outlet and an impurity outlet;

[0102] The material inlet of the vinyl chloride tower is connected to the material outlet of the hydrogen chloride tower through a liquid pipeline;

[0103] The material outlet of the vinyl chloride tower is connected to the vinyl chloride stripping tower;

[0104] The impurity outlet of the vinyl chloride tower is connected to the chlorination reactor.

[0105] Furthermore, the chlorination reactor is provided with a material inlet and a material outlet;

[0106] The material inlet of the chlorination reactor is connected to the impurity outlet of the vinyl chloride tower through a liquid pipeline;

[0107] The material outlet of the chlorination reactor is connected to the circulating material inlet of the high boiling tower through a liquid pipeline;

[0108] The chlorination reactor is also provided with a chlorine gas inlet.

[0109] Furthermore, the vinyl chloride stripping tower is provided with a material inlet, a material outlet, and an impurity outlet;

[0110] The material inlet of the vinyl chloride stripping tower is connected to the material outlet of the vinyl chloride tower through a liquid pipeline;

[0111] The material outlet of the vinyl chloride stripping tower is connected to the vinyl chloride storage tank;

[0112] The impurity outlet of the vinyl chloride stripping tower is connected to the circulating gas outlet of the hydrogen chloride tower through a gas pipeline;

[0113] The impurity outlet of the vinyl chloride stripping tower is arranged at the top of the vinyl chloride stripping tower;

[0114] The material outlet of the vinyl chloride stripping tower is arranged below the vinyl chloride stripping tower.

[0115] Furthermore, the vinyl chloride storage tank is provided with a material inlet;

[0116] The material inlet of the vinyl chloride storage tank is connected to the material outlet of the vinyl chloride stripping tower through a liquid pipeline.

[0117] Furthermore, the efficiency of the system in preparing vinyl chloride is 90-99%.

[0118] Beneficial effects of the utility model:

[0119] 1. The system for producing vinyl chloride by oxychlorination in the utility model prepares ethylene dichloride through an oxychlorination reaction unit, and then purifies the ethylene dichloride through a refining unit. Next, the refined ethylene dichloride is cracked in a cracking unit to prepare vinyl chloride, and finally purified in a vinyl chloride refining unit to obtain vinyl chloride. In addition, ethylene dichloride is also prepared through a direct chlorination reaction unit, thereby increasing the output of ethylene dichloride and providing raw materials for the cracking of ethylene dichloride. The system for producing vinyl chloride by oxychlorination in the utility model prepares ethylene dichloride through both the oxychlorination reaction unit and the direct chlorination unit, thereby improving the working efficiency of the system.

[0120] 2. The hydrogen chloride produced in the vinyl chloride refining unit in the system for producing vinyl chloride by oxychlorination of the utility model will be returned to the oxychlorination reaction unit as a raw material, thereby avoiding the generation of waste gas and saving production costs. The cooling water produced in the separation tank in the oxychlorination reaction unit will be returned to the oxychlorination hot quenching tower for recycling, and the vapor phase in the oxychlorination hot quenching tower will be quenched, thereby avoiding energy waste, reducing consumption, and facilitating industrial production.

[0121] 3. The system for producing vinyl chloride by oxychlorination of the utility model utilizes an oxychlorination reaction unit and a direct chlorination reaction unit to prepare ethylene dichloride, and does not need to use mercuric chloride as a catalyst to prepare ethylene dichloride. The preparation process is non-toxic and harmless, which ensures the safety of the experimenters and provides a safe environment for industrial production.

[0122] 4. The purity of the vinyl chloride synthesized in the system for producing vinyl chloride by oxychlorination of the utility model can reach 99.5-99.8%wt. BRIEF DESCRIPTION OF THE DRAWINGS

[0123] Figure 1 This is a device diagram of the system for producing vinyl chloride by oxychlorination according to the utility model.

[0124] The names of the numbers in the figure are: A, oxychlorination reaction unit, B, dichloroethane refining unit, C, direct chlorination unit, D, cracking unit, E, vinyl chloride refining unit, F, incineration unit, G, waste liquid treatment unit, 1, hydrogenation reactor, 2, oxychlorination reactor, 3, oxychlorination hot quenching tower, 4, carbon dioxide stripping tower, 5, separation tank, 6, alkali washing tank, 7, dichloroethane storage tank, 8, light removal tower, 9, high boiling tower, 10, vacuum tower, 11, dichloroethane product tank, 12, direct chlorination reactor, 13, cracking furnace, 14, cracking quenching washing tower, 15, hydrogen chloride tower, 16, vinyl chloride tower, 17, chlorination reactor, 18, vinyl chloride stripping tower, 19, vinyl chloride storage tank. DETAILED DESCRIPTION

[0125] The invention is described in detail below with reference to the embodiments:

[0126] The utility model provides a system for producing vinyl chloride by oxychlorination. The process of preparing vinyl chloride by the system is non-toxic and environmentally friendly. Hydrogen chloride and cooling water in the preparation process can be returned to the system for repeated use, which greatly reduces the production energy consumption of the system.

[0127] Example 1

[0128] The present embodiment provides a system for producing vinyl chloride by oxychlorination. According to the flow direction of the materials, the system sequentially comprises an oxychlorination reaction unit A, an ethylene dichloride refining unit B, a direct chlorination unit C, a cracking unit D and a vinyl chloride refining unit E; the oxychlorination reaction unit A is respectively connected to the ethylene dichloride refining unit B and the vinyl chloride refining unit E; the ethylene dichloride refining unit B is also respectively connected to the direct chlorination unit C and the cracking unit D; the cracking unit D is also connected to the vinyl chloride refining unit E; the vinyl chloride refining unit E is also respectively connected to the oxychlorination reaction unit A; the system further comprises an incineration unit F and a waste liquid treatment unit G; the oxychlorination The reaction unit A comprises a hydrogenation reactor 1, an oxychlorination reactor 2, an oxychlorination hot quenching tower 3, a carbon dioxide stripping tower 4, a separation tank 5, an alkali washing tank 6 and an ethylene dichloride storage tank 7; the ethylene dichloride refining unit B comprises a light removal tower 8, a high boiling tower 9, a vacuum tower 10 and an ethylene dichloride product tank 11; the direct chlorination unit C comprises a direct chlorination reactor 12; the cracking unit D comprises a cracking furnace 13 and a cracking quenching washing tower 14; the vinyl chloride refining unit E comprises a hydrogen chloride tower 15, a vinyl chloride tower 16, a chlorination reactor 17, a vinyl chloride stripping tower 18 and a vinyl chloride storage tank 19; the system also comprises an incineration unit F and a waste liquid treatment unit G.

[0129] In this embodiment, the hydrogenation reactor 1 is provided with a hydrogen chloride inlet and a hydrogen chloride outlet. The hydrogen chloride inlet of the hydrogenation reactor 1 is connected to the hydrogen chloride tower 15, and the hydrogen chloride outlet of the hydrogenation reactor 1 is connected to the oxychlorination reactor 2. The hydrogenation reactor 1 is also provided with a hydrogen inlet;

[0130] A material outlet is provided above the oxychlorination reactor 2, and the oxychlorination reactor 2 is also provided with a hydrogen chloride inlet, an oxygen inlet, an ethylene inlet, a circulating inlet, a heat carrier inlet and a heat carrier outlet. The material outlet of the oxychlorination reactor 2 is connected to the oxychlorination hot quenching tower 3, the hydrogen chloride inlet of the oxychlorination reactor 2 is connected to the hydrogen chloride outlet of the hydrogenation reactor 1 through a gas pipeline, and the circulating inlet of the oxychlorination reactor 2 is connected to the oxychlorination hot quenching tower 3;

[0131] The top of the oxychlorination heat quenching tower 3 is provided with a circulating air outlet and a waste gas outlet. The oxychlorination heat quenching tower 3 is also provided with a material inlet, a water inlet and a material outlet. The circulating air outlet of the oxychlorination heat quenching tower 3 is connected to the circulating air inlet of the oxychlorination reactor 2 through a gas pipeline. The waste gas outlet of the oxychlorination heat quenching tower 3 is connected to the incineration unit F through a gas pipeline. The material inlet of the oxychlorination heat quenching tower 3 is connected to the material outlet of the oxychlorination reactor 2 through a gas pipeline. The water inlet of the tower 3 is connected to the separation tank 5, and the material outlet of the oxychlorination heat quenching tower 3 is connected to the carbon dioxide stripping tower 4; a spray device is provided on the top of the oxychlorination heat quenching tower 3, and the spray device of the oxychlorination heat quenching tower 3 is provided with cooling water from the water inlet of the oxychlorination heat quenching tower 3, and the cooling water is sprayed from top to bottom in the oxychlorination heat quenching tower 3; the circulating gas outlet and the waste gas outlet of the oxychlorination heat quenching tower 3 simultaneously discharge gas to the oxychlorination reactor 2 and the incineration unit F to maintain system balance;

[0132] The carbon dioxide stripping tower 4 is provided with a material inlet, a nitrogen inlet and a material outlet; the material inlet of the carbon dioxide stripping tower 4 is connected to the material outlet of the oxychlorination heat quenching tower 3 through a liquid pipeline, the material outlet of the carbon dioxide stripping tower 4 is connected to the separation tank 5, the carbon dioxide stripping tower 4 is also provided with a nitrogen inlet, and the material outlet of the carbon dioxide stripping tower 4 is arranged below the carbon dioxide stripping tower 4;

[0133] The separation tank 5 is provided with a material inlet, a water outlet and a material outlet; the material inlet of the separation tank 5 is connected to the material outlet of the carbon dioxide stripping tower 4 through a liquid pipeline, the water outlet of the separation tank 5 is connected to the water inlet of the oxychlorination thermal quenching tower 3 through a liquid pipeline, and the material outlet of the separation tank 5 is connected to the alkali washing tank 6; the water outlet of the separation tank 5 is arranged at the bottom of the separation tank 5, and the material outlet of the separation tank 5 is arranged on the side;

[0134] The alkali washing tank 6 is provided with a material inlet, a material outlet and a waste liquid outlet; the material inlet of the alkali washing tank 6 is connected to the material outlet of the separation tank 5 through a liquid pipeline, the material outlet of the alkali washing tank 6 is connected to the dichloroethane storage tank 7, and the waste liquid outlet of the alkali washing tank 6 is connected to the waste liquid treatment unit G through a liquid pipeline; the waste liquid outlet of the alkali washing tank 6 is arranged at the bottom of the alkali washing tank 6, and an alkaline liquid is passed through the alkali washing tank 6 to wash the product in the alkali washing tank 6;

[0135] The dichloroethane storage tank 7 is provided with a material inlet and a material outlet; the material inlet of the dichloroethane storage tank 7 is connected to the material outlet of the alkali washing tank 6 through a liquid pipeline, and the material outlet of the dichloroethane storage tank 7 is connected to the light removal tower 8;

[0136] The de-lightening tower 8 is provided with a material inlet, a material outlet and a waste gas outlet; the material inlet of the de-lightening tower 8 is connected to the material outlet of the dichloroethane storage tank 7 through a liquid pipeline, the material outlet of the de-lightening tower 8 is connected to the high boiling tower 9 through a liquid pipeline, the waste gas outlet of the de-lightening tower 8 is connected to the incineration unit F and the waste liquid treatment unit G through a pipeline, and a condenser is provided on the pipeline connecting the waste gas outlet of the de-lightening tower 8 with the incineration unit F and the waste liquid treatment unit G; the material outlet of the de-lightening tower 8 is arranged below the de-lightening tower 8, and the waste gas outlet of the de-lightening tower 8 is arranged at the top of the de-lightening tower 8;

[0137] The high boiling tower 9 is provided with a liquid material inlet, a circulating material inlet, a gas material inlet, a material outlet and a circulating liquid inlet; the liquid material inlet of the high boiling tower 9 is connected to the material outlet of the light removal tower 8 through a liquid pipeline, the circulating material inlet of the high boiling tower 9 is also connected to the chlorination reactor 17 through a liquid pipeline, the circulating liquid inlet of the high boiling tower 9 is connected to the direct chlorination reactor 12, the gas material inlet of the high boiling tower 9 is connected to the direct chlorination reactor 12, and the material outlet of the high boiling tower 9 is connected to the dichloroethane product tank 11; the material outlet of the high boiling tower 9 is arranged at the top of the high boiling tower 9, and the circulating liquid inlet of the high boiling tower 9 is arranged below the high boiling tower 9;

[0138] The vacuum tower 10 is provided with a material inlet, a material outlet and an impurity port; the material inlet of the vacuum tower 10 is connected to the cracking quenching washing tower 14, the material outlet of the vacuum tower 10 is connected to the dichloroethane product tank 11, and the impurity port of the vacuum tower 10 is connected to the incineration unit F; the material outlet of the vacuum tower 10 is arranged at the top of the vacuum tower 10, and the impurity port of the vacuum tower 10 is arranged at the bottom of the vacuum tower 10;

[0139] The dichloroethane product tank 11 is provided with a material inlet and a material outlet. The material inlet of the dichloroethane product tank 11 is connected to the material outlet of the high boiling tower 9 through a pipeline, and is also connected to the material outlet of the vacuum tower 10 through a pipeline. The material outlet of the dichloroethane product tank 11 is connected to the cracking furnace 13; a condenser is provided on the pipeline connecting the material inlet of the dichloroethane product tank 11 with the high boiling tower 9 and the vacuum tower 10, and the vapor material is converted into liquid through the condenser; the material outlet of the dichloroethane product tank 11 is provided below the dichloroethane product tank 11;

[0140] The direct chlorination reactor 12 is provided with an ethylene gas inlet, a chlorine gas inlet, a material outlet and a circulating liquid inlet; the material outlet of the direct chlorination reactor 12 is connected to the gas material inlet of the high boiling tower 9 through a gas pipeline, and the circulating liquid inlet of the direct chlorination reactor 12 is connected to the circulating liquid inlet of the high boiling tower 9 through a liquid pipeline; the material outlet of the direct chlorination reactor 12 is arranged above the direct chlorination reactor 12;

[0141] The cracking furnace 13 is provided with a material inlet and a material outlet; the material inlet of the cracking furnace 13 is connected to the material outlet of the dichloroethane product tank 11 through a liquid pipeline, and the material outlet of the cracking furnace 13 is connected to the cracking quenching washing tower 14;

[0142] The cracking quenching washing tower 14 is provided with a material inlet, a gas material outlet, a liquid material outlet and an impurity outlet; the material inlet of the cracking quenching washing tower 14 is connected to the material outlet of the cracking furnace 13 through a gas pipeline, the gas material outlet of the cracking quenching washing tower 14 is connected to the hydrogen chloride tower 15, the liquid material outlet of the cracking quenching washing tower 14 is connected to the hydrogen chloride tower 15, and the impurity outlet of the cracking quenching washing tower 14 is connected to the material inlet of the vacuum tower 10 through a liquid pipeline; the gas material outlet of the cracking quenching washing tower 14 is arranged at the top of the cracking quenching washing tower 14, and the impurity outlet of the cracking quenching washing tower 14 is arranged below the cracking quenching washing tower 14; a condenser is arranged above the cracking quenching washing tower 14 to condense and reflux the product in the cracking quenching washing tower 14;

[0143] The hydrogen chloride tower 15 is provided with a hydrogen chloride gas outlet, a material inlet, a circulating gas outlet and a material outlet; the hydrogen chloride gas outlet of the hydrogen chloride tower 15 is connected to the hydrogen chloride gas inlet of the hydrogenation reactor 1 through a gas pipeline, the material inlet of the hydrogen chloride tower 15 is connected to the liquid material outlet of the cracking quenching washing tower 14 through a liquid pipeline, the material inlet of the hydrogen chloride tower 15 is also connected to the gas material outlet of the cracking quenching washing tower 14 through a pipeline, and a condenser is installed on the pipeline connecting the material inlet of the hydrogen chloride tower 15 and the gas material outlet of the cracking quenching washing tower 14, and the gaseous material becomes liquid after passing through the condenser; the circulating gas outlet of the hydrogen chloride tower 15 is connected to the vinyl chloride stripping tower 18, and the material outlet of the hydrogen chloride tower 15 is connected to the vinyl chloride tower 16; the hydrogen chloride gas outlet of the hydrogen chloride tower 15 is arranged at the top of the hydrogen chloride tower 15, and the material outlet of the hydrogen chloride tower 15 is arranged below the hydrogen chloride tower 15;

[0144] The vinyl chloride tower 16 is provided with a material inlet, a material outlet and an impurity outlet; the material inlet of the vinyl chloride tower 16 is connected to the material outlet of the hydrogen chloride tower 15 through a liquid pipeline, the material outlet of the vinyl chloride tower 16 is connected to the vinyl chloride stripping tower 18, and the impurity outlet of the vinyl chloride tower 16 is connected to the chlorination reactor 17;

[0145] The chlorination reactor 17 is provided with a material inlet and a material outlet. The material inlet of the chlorination reactor 17 is connected to the impurity outlet of the vinyl chloride tower 16 through a liquid pipeline. The material outlet of the chlorination reactor 17 is connected to the circulating material inlet of the high boiling tower 9 through a liquid pipeline. The chlorination reactor 17 is also provided with a chlorine gas inlet.

[0146] The vinyl chloride stripping tower 18 is provided with a material inlet, a material outlet, and an impurity outlet; the material inlet of the vinyl chloride stripping tower 18 is connected to the material outlet of the vinyl chloride tower 16 through a liquid pipeline, the material outlet of the vinyl chloride stripping tower 18 is connected to the vinyl chloride storage tank 19, and the impurity outlet of the vinyl chloride stripping tower 18 is connected to the circulating gas port of the hydrogen chloride tower 15 through a gas pipeline; the impurity outlet of the vinyl chloride stripping tower 18 is arranged at the top of the vinyl chloride stripping tower 18, and the material outlet of the vinyl chloride stripping tower 18 is arranged below the vinyl chloride stripping tower 18;

[0147] The vinyl chloride storage tank 19 is provided with a material inlet, and the material inlet of the vinyl chloride storage tank 19 is connected to the material outlet of the vinyl chloride stripping tower 18 through a liquid pipeline.

[0148] In this embodiment, in the oxychlorination reaction unit A, hydrogen enters the hydrogenation reactor 1 through the hydrogen chloride inlet of the hydrogenation reactor 1, and the vapor material therein is subjected to hydrogenation reaction, and the obtained hydrogen chloride gas enters the hydrogen chloride inlet of the oxychlorination reactor 2 through the hydrogen chloride outlet of the hydrogenation reactor 1 through the gas pipeline, oxygen enters through the oxygen inlet of the oxychlorination reactor 2, and ethylene enters through the ethylene inlet of the oxychlorination reactor 2. The hydrogen chloride gas, ethylene and oxygen react in the oxychlorination reactor 2 to obtain the vapor material, and the oxychlorination reactor 2 enters the material inlet of the oxychlorination heat quenching tower 3, and the spraying device at the top of the oxychlorination heat quenching tower 3 sprays cooling water from top to bottom to quench the vapor material in the oxychlorination heat quenching tower 3, wherein the vapor material that has not been quenched enters the circulating air inlet of the oxychlorination reactor 2 through the circulating air outlet at the top of the oxychlorination heat quenching tower 3 to continue to react, and a small part of the vapor material that has not been quenched enters the incineration unit F through the waste gas outlet at the top of the oxychlorination heat quenching tower 3 for post-treatment, and the quenched vapor material passes through the material outlet of the oxychlorination heat quenching tower 3 through the liquid outlet. The carbon dioxide stripping tower 4 is reacted in the carbon dioxide stripping tower 4 to obtain crude ethylene dichloride, which contains water. The crude ethylene dichloride enters the material inlet of the separation tank 5 through the liquid pipeline via the material outlet below the carbon dioxide stripping tower 4. The crude ethylene dichloride is separated in the separation tank 5 to obtain ethylene dichloride and cooling water. The cooling water passes through the water outlet at the bottom of the separation tank 5. The liquid pipeline enters the water inlet of the oxychlorination hot quenching tower 3 to provide cooling water for the oxychlorination hot quenching tower 3. The dichloroethane obtained in the separation tank 5 enters the material inlet of the alkali washing tank 6 through the material outlet on the side of the separation tank 5 through the liquid pipeline. The alkali washing tank 6 is passed with alkaline liquid to wash the dichloroethane. The washed dichloroethane enters the dichloroethane storage tank 7 through the material outlet of the alkali washing tank 6 through the liquid pipeline. The waste liquid generated after washing is connected to the waste liquid treatment unit G through the waste liquid outlet at the bottom of the alkali washing tank 6 through the liquid pipeline;

[0149] The ethylene dichloride in the ethylene dichloride storage tank 7 continues to enter the ethylene dichloride refining unit B, wherein the ethylene dichloride enters the material inlet of the light-removing tower 8 through the material outlet of the ethylene dichloride storage tank 7 through the liquid pipeline, and the light component impurities of the ethylene dichloride are removed in the light-removing tower 8, and the light component impurities pass through the exhaust gas outlet at the top of the light-removing tower 8 through the gas pipeline and the condenser, wherein the condensable light component impurities enter the waste liquid treatment unit G through the liquid pipeline, and the non-condensable light component impurities enter the incineration unit F through the gas pipeline, and the ethylene dichloride with the light component removed enters the liquid material inlet of the high boiling tower 9 through the material outlet below the light-removing tower 8 through the liquid pipeline;

[0150] At the same time, ethylene is introduced into the direct chlorination reactor 12 in the direct chlorination unit C through the ethylene inlet, and chlorine is introduced through the chlorine inlet, and a reaction is carried out in the direct chlorination reactor 12, and the obtained ethylene dichloride vapor enters the gas material inlet of the high boiling tower 9 through the material outlet above the direct chlorination reactor 12 through the gas pipeline, and the liquid ethylene dichloride in the high boiling tower 9 enters the circulating liquid inlet of the direct chlorination reactor 12 through the circulating liquid outlet at the bottom of the high boiling tower 9 through the liquid pipeline for circulation;

[0151] The gaseous ethylene dichloride in the high boiling tower 9 passes through the material outlet at the top of the high boiling tower 9 through the gas pipeline, is converted into liquid through the condenser, and enters the material inlet of the ethylene dichloride product tank 11 to obtain the ethylene dichloride product;

[0152] The dichloroethane product enters the cracking furnace 13 of the cracking unit D through the material outlet of the dichloroethane product tank 11 through the liquid pipeline for cracking, and the obtained vinyl chloride crude product enters the product of the cracking quenching washing tower 14 through the material outlet of the cracking furnace 13 through the liquid pipeline, and is condensed and refluxed in the cracking quenching washing tower 14 through the condenser above the cracking quenching washing tower 14, wherein part of the dichloroethane, vinyl chloride and hydrogen chloride are condensed, wherein a small part of the condensed dichloroethane enters the material inlet of the vacuum tower 10 through the impurity outlet below the cracking quenching washing tower 14 through the liquid pipeline for circulation, and most of the condensed dichloroethane, vinyl chloride and hydrogen chloride enter the material inlet of the hydrogen chloride tower 15 through the liquid material outlet of the cracking quenching washing tower 14 through the liquid pipeline, and the uncondensed product in the cracking quenching washing tower 14 enters the material inlet of the hydrogen chloride tower 15 through the gas material outlet at the top of the cracking quenching washing tower 14 through the gas pipeline, and then condensed by the condenser;

[0153] Ethyl chloride, vinyl chloride and hydrogen chloride enter the hydrogen chloride tower 15 of the vinyl chloride synthesis unit E from the cracking quenching washing tower 14 of the cracking unit D. In the hydrogen chloride tower 15, the hydrogen chloride in the vinyl chloride enters the hydrogen chloride gas inlet of the hydrogenation reactor 1 through the hydrogen chloride gas outlet at the top of the hydrogen chloride tower 15 through a gas pipeline for reuse. The mixture of ethyl chloride and vinyl chloride enters the material inlet of the vinyl chloride tower 16 through the material outlet at the bottom of the hydrogen chloride tower 15 through a liquid pipeline. In the vinyl chloride tower 16, the vinyl chloride enters the material inlet of the vinyl chloride stripping tower 18 through the material outlet at the vinyl chloride tower 16 through a liquid pipeline, and enters the material inlet of the vinyl chloride storage tank 19 through the material outlet at the bottom of the vinyl chloride stripping tower 18 through a liquid pipeline to obtain vinyl chloride;

[0154] In addition, the hydrogen chloride and a small amount of vinyl chloride in the vinyl chloride stripping tower 18 enter the circulating gas port of the hydrogen chloride tower 15 through the impurity outlet at the top of the vinyl chloride stripping tower 18 for circulation, and the impurity outlet of the vinyl chloride tower 16 is also connected to the material inlet of the chlorination reactor 17. Chlorine is introduced into the chlorine inlet of the chlorination reactor 17 to obtain crude dichloroethane. The crude dichloroethane enters the liquid material of the high boiling tower 9 through the material outlet of the chlorination reactor 17 through a liquid pipeline for recycling.

[0155] The purity of the vinyl chloride obtained in this example is 99.95%wt.

[0156] Based on the above, it can be seen that the system for producing vinyl chloride by oxychlorination described in this application has a wide range of applications, low cost, and extremely high market prospects.

[0157] The above is only a preferred embodiment of the present invention and does not constitute any other limitation on the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. A system for producing vinyl chloride by oxychlorination, characterized in that: According to the flow direction of the materials, the system sequentially comprises an oxychlorination reaction unit (A), an ethylene dichloride refining unit (B), a direct chlorination unit (C), a cracking unit (D) and a vinyl chloride refining unit (E); The oxychlorination reaction unit (A) is connected to the ethylene dichloride refining unit (B) and the vinyl chloride refining unit (E) respectively; The ethylene dichloride refining unit (B) is also connected to a direct chlorination unit (C) and a cracking unit (D) respectively; The cracking unit (D) is also connected to a vinyl chloride refining unit (E); The vinyl chloride refining unit (E) is also connected to the oxychlorination reaction unit (A) respectively; The system further comprises an incineration unit (F) and a waste liquid treatment unit (G).

2. The system according to claim 1, characterized in that: The oxychlorination reaction unit (A) comprises a hydrogenation reactor (1), an oxychlorination reactor (2), an oxychlorination hot quenching tower (3), a carbon dioxide stripping tower (4), a separation tank (5), an alkali washing tank (6) and an ethylene dichloride storage tank (7).

3. The system according to claim 2, characterized in that: The dichloroethane refining unit (B) comprises a lightness removal tower (8), a high boiling tower (9), a vacuum tower (10) and an ethylene dichloride product tank (11).

4. The system according to claim 3, characterized in that: The direct chlorination unit (C) comprises a direct chlorination reactor (12).

5. The system according to claim 4, characterized in that: The cracking unit (D) comprises a cracking furnace (13) and a cracking quenching washing tower (14).

6. The system according to claim 5, characterized in that: The vinyl chloride refining unit (E) comprises a hydrogen chloride tower (15), a vinyl chloride tower (16), a chlorination reactor (17), a vinyl chloride stripping tower (18) and a vinyl chloride storage tank (19).

7. The system according to claim 2, characterized in that: A material outlet is provided above the oxychlorination reactor (2), and the oxychlorination reactor (2) is also provided with a hydrogen chloride air inlet, an oxygen air inlet, an ethylene air inlet, a circulating air inlet, a heat carrier inlet and a heat carrier outlet; The material outlet of the oxychlorination reactor (2) is connected to the oxychlorination hot quenching tower (3); The hydrogen chloride inlet of the oxychlorination reactor (2) is connected to the hydrogen chloride outlet of the hydrogenation reactor (1) via a gas pipeline; The circulating air inlet of the oxychlorination reactor (2) is connected to the oxychlorination hot quenching tower (3); The oxychlorination reactor (2) discharges and inputs heat via a heat carrier inlet and a heat carrier outlet.

8. The system according to claim 2, characterized in that: The top of the oxychlorination heat quenching tower (3) is provided with a circulating gas outlet and a waste gas outlet, and the oxychlorination heat quenching tower (3) is also provided with a material inlet, a water inlet and a material outlet; The circulating gas outlet of the oxychlorination hot quenching tower (3) is connected to the circulating gas inlet of the oxychlorination reactor (2) through a gas pipeline; The exhaust gas outlet of the oxychlorination heat quenching tower (3) is connected to the incineration unit (F) via a gas pipeline; The material inlet of the oxychlorination heat quenching tower (3) is connected to the material outlet of the oxychlorination reactor (2) through a gas pipeline; The water inlet of the oxychlorination heat quenching tower (3) is connected to the separation tank (5); The material outlet of the oxychlorination heat quenching tower (3) is connected to the carbon dioxide stripping tower (4).

9. The system according to claim 2, characterized in that: The separation tank (5) is provided with a material inlet, a water outlet and a material outlet; The material inlet of the separation tank (5) is connected to the material outlet of the carbon dioxide stripping tower (4) via a liquid pipeline; The water outlet of the separation tank (5) is connected to the water inlet of the oxychlorination thermal quenching tower (3) via a liquid pipeline; The material outlet of the separation tank (5) is connected to the alkali washing tank (6); The water outlet of the separation tank (5) is arranged at the bottom of the separation tank (5), and the material outlet of the separation tank (5) is arranged on the side.

10. The system according to claim 3, characterized in that: The lightness removal tower (8) is provided with a material inlet, a material outlet and an exhaust gas outlet; The material inlet of the lightness removal tower (8) is connected to the material outlet of the dichloroethane storage tank (7) via a liquid pipeline; The material outlet of the light removal tower (8) is connected to the high boiling tower (9) via a liquid pipeline; The exhaust gas outlet of the light-removal tower (8) is connected to the incineration unit (F) and the waste liquid treatment unit (G) via a pipeline; A condenser is provided on the pipeline connecting the exhaust gas outlet of the light removal tower (8) with the incineration unit (F) and the waste liquid treatment unit (G); The material outlet of the lightness removal tower (8) is arranged below the lightness removal tower (8), and the exhaust gas outlet of the lightness removal tower (8) is arranged at the top of the lightness removal tower (8).

11. The system according to claim 6, characterized in that: The high boiling tower (9) is provided with a liquid material inlet, a circulating material inlet, a gas material inlet, a material outlet and a circulating liquid inlet; The liquid material inlet of the high boiling tower (9) is connected to the material outlet of the light removal tower (8) through a liquid pipeline; The circulating material inlet of the high boiling tower (9) is also connected to the chlorination reactor (17) through a liquid pipeline; The circulating liquid port of the high boiling tower (9) is connected to the direct chlorination reactor (12); The gas material inlet of the high boiling tower (9) is connected to the direct chlorination reactor (12); The material outlet of the high boiling tower (9) is connected to the ethylene dichloride product tank (11); The material outlet of the high boiling tower (9) is arranged at the top of the high boiling tower (9), and the circulating liquid inlet of the high boiling tower (9) is arranged below the high boiling tower (9).

12. The system according to claim 5, characterized in that: The vacuum tower (10) is provided with a material inlet, a material outlet and an impurity outlet; The material inlet of the vacuum tower (10) is connected to the cracking quenching washing tower (14); The material outlet of the vacuum tower (10) is connected to the dichloroethane product tank (11); The impurity port of the vacuum tower (10) is connected to an incineration unit (F); The material outlet of the vacuum tower (10) is arranged at the top of the vacuum tower (10), and the impurity outlet of the vacuum tower (10) is arranged below the vacuum tower (10).

13. The system according to claim 4, characterized in that: The direct chlorination reactor (12) is provided with an ethylene inlet, a chlorine inlet, a material outlet and a circulating liquid inlet; The material outlet of the direct chlorination reactor (12) is connected to the gas material inlet of the high boiling tower (9) via a gas pipeline; The circulating liquid inlet of the direct chlorination reactor (12) is connected to the circulating liquid inlet of the high boiling tower (9) via a liquid pipeline; The material outlet of the direct chlorination reactor (12) is arranged above the direct chlorination reactor (12).

14. The system according to claim 6, characterized in that: The hydrogen chloride tower (15) is provided with a hydrogen chloride gas outlet, a material inlet, a circulating gas inlet and a material outlet; The hydrogen chloride gas outlet of the hydrogen chloride tower (15) is connected to the hydrogen chloride gas inlet of the hydrogenation reactor (1) through a gas pipeline; The material inlet of the hydrogen chloride tower (15) is connected to the liquid material outlet of the cracking quenching washing tower (14) through a liquid pipeline; The material inlet of the hydrogen chloride tower (15) is also connected to the gas material outlet of the cracking quenching washing tower (14) through a pipeline; A condenser is installed on the pipeline connecting the material inlet of the hydrogen chloride tower (15) and the gas material outlet of the cracking quenching washing tower (14), and the gaseous material becomes liquid after passing through the condenser; The circulating gas port of the hydrogen chloride tower (15) is connected to the vinyl chloride stripping tower (18); The material outlet of the hydrogen chloride tower (15) is connected to the vinyl chloride tower (16); The hydrogen chloride gas outlet of the hydrogen chloride tower (15) is arranged at the top of the hydrogen chloride tower (15), and the material outlet of the hydrogen chloride tower (15) is arranged below the hydrogen chloride tower (15).

15. The system according to claim 6, characterized in that: The vinyl chloride tower (16) is provided with a material inlet, a material outlet and an impurity outlet; The material inlet of the vinyl chloride tower (16) is connected to the material outlet of the hydrogen chloride tower (15) via a liquid pipeline; The material outlet of the vinyl chloride tower (16) is connected to the vinyl chloride stripping tower (18); The impurity outlet of the vinyl chloride tower (16) is connected to the chlorination reactor (17).

16. The system according to claim 6, characterized in that: The chlorination reactor (17) is provided with a material inlet and a material outlet; The material inlet of the chlorination reactor (17) is connected to the impurity outlet of the vinyl chloride tower (16) via a liquid pipeline; The material outlet of the chlorination reactor (17) is connected to the circulating material inlet of the high boiling tower (9) via a liquid pipeline; The chlorination reactor (17) is also provided with a chlorine gas inlet.

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