Vinyl chloride preparation device and vinyl chloride preparation method

Abstract

The invention discloses a vinyl chloride preparation device and a vinyl chloride preparation method. The vinyl chloride preparation device comprises a compression mechanism and a cracking furnace. And the compression mechanism is used for compressing 1, 2-dichloroethane into a high-temperature and high-pressure gas phase. And the cracking furnace is connected with the compression mechanism so as to crack the compressed high-temperature and high-pressure gas-phase 1, 2-dichloroethane to form cracked gas containing vinyl chloride. When vinyl chloride is prepared, electric energy is mainly consumed, the use amount of a refining system cooling medium and a vaporization heat source of cracking raw material 1, 2-dichloroethane can be greatly reduced, meanwhile, heat of a cracking convection section and heat of thermal cracking gas are recycled respectively, the effect of remarkably reducing vinyl chloride production energy consumption is achieved, and the purposes of reducing cost and improving efficiency are achieved.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a vinyl chloride preparation device and a vinyl chloride preparation method. Background Art

[0002] Vinyl chloride (VCM) is a key monomer in the production of polyvinyl chloride (PVC). Traditionally, the mainstream production process for this monomer utilizes 1,2-dichloroethane (EDC) cracking to produce VCM. This process involves refining crude EDC to obtain a refined EDC product suitable for cracking. Liquid EDC is vaporized under pressure and then fed into a cracking furnace for cracking. However, this traditional process for producing VCM through cracking suffers from high energy consumption. Summary of the Invention

[0003] Based on this, it is necessary to provide a vinyl chloride preparation device that can reduce energy consumption.

[0004] An embodiment of the present application provides a vinyl chloride production device.

[0005] A vinyl chloride preparation device, comprising:

[0006] A compression mechanism, the compression mechanism being used to compress 1,2-dichloroethane to generate a high-temperature and high-pressure gas phase;

[0007] and a cracking furnace connected to the compression mechanism to crack the compressed high-temperature and high-pressure gas phase 1,2-dichloroethane to form cracked gas containing vinyl chloride.

[0008] In some embodiments, the vinyl chloride production apparatus further includes a heat recovery mechanism, which is connected to the cracking furnace for recovering heat from a convection section within the cracking furnace through heat exchange.

[0009] In some embodiments, the heat recovery mechanism includes a heat exchange coil, which is disposed in the cracking furnace to perform heat exchange and recovery on the convection section of the cracking furnace.

[0010] In some embodiments, the heat recovery mechanism further includes a steam generating device, which is connected to the cracking furnace and communicates with the cracking gas outlet of the cracking furnace. The steam generating device can utilize the cracking gas from the cracking gas outlet to heat the liquid medium to increase the temperature of the liquid medium and / or generate steam.

[0011] In some embodiments, the steam generating device is also connected to the flue gas outlet of the cracking furnace, and the steam generating device can use the flue gas from the flue gas outlet to heat the liquid medium to increase the temperature of the liquid medium and / or generate steam.

[0012] In some embodiments, the vinyl chloride preparation apparatus further includes a deweighting tower for removing heavy impurities from a raw material containing 1,2-dichloroethane. The deweighting tower is located upstream of the compression mechanism. The top outlet of the deweighting tower is communicated with the compression mechanism and inputs a gas phase containing 1,2-dichloroethane after the heavy impurities are removed into the compression mechanism.

[0013] In some embodiments, the vinyl chloride preparation apparatus further comprises a de-weighting reboiler, which is connected to the bottom of the de-weighting tower to reboil the material at the bottom outlet of the de-weighting tower and reflux it to the de-weighting tower.

[0014] In some embodiments, the vinyl chloride preparation device also includes a first condensation pipe connecting the top outlet and the top reflux port of the deweighting tower, and a first condenser, a first reflux storage tank and a first reflux pump sequentially arranged on the first condensation pipe along the flow direction.

[0015] In some embodiments, the vinyl chloride production apparatus further includes a vapor-liquid separator, which is connected in series between the deweighting tower and the compression mechanism to perform gas-liquid separation on the gas phase at the top outlet of the deweighting tower.

[0016] In some embodiments, the vinyl chloride preparation apparatus further includes a light-removing tower for removing light component impurities from a raw material containing 1,2-dichloroethane. The light-removing tower is located upstream of the heavy-removing tower and connected to the heavy-removing tower, and the bottom outlet of the light-removing tower is connected to the feed inlet of the heavy-removing tower.

[0017] In some embodiments, the vinyl chloride preparation apparatus further comprises a light removal reboiler, which is connected to the bottom of the light removal tower to reboil the material at the bottom outlet of the light removal tower and reflux it to the light removal tower.

[0018] In some embodiments, the vinyl chloride preparation device also includes a second condensation pipe connecting the top outlet of the light removal tower and the light removal reflux port of the tower, and a second condenser, a second reflux storage tank and a second reflux pump sequentially arranged on the second condensation pipe along the flow direction.

[0019] In some embodiments, the light-removal tower comprises a distillation tower capable of separating light component impurities including hydrogen chloride and carbon tetrachloride.

[0020] An embodiment of the present application provides a method for preparing vinyl chloride.

[0021] A method for preparing vinyl chloride comprises the following steps:

[0022] Controlling the compression mechanism to compress 1,2-dichloroethane into a high-temperature and high-pressure gas phase;

[0023] Furthermore, the cracking furnace is controlled to crack the compressed high-temperature and high-pressure gas phase 1,2-dichloroethane to form a cracking gas containing vinyl chloride.

[0024] In some embodiments, a heat recovery mechanism connected to the cracking furnace is controlled to recover heat from a convection section within the cracking furnace through heat exchange.

[0025] In some embodiments, the heat exchange medium in the heat exchange coil includes one or more of boiler water, steam, air, fuel gas and 1,2-dichloroethane.

[0026] In some embodiments, the cracked gas from the cracked gas outlet of the cracking furnace is controlled to heat the liquid medium of the steam generating device to increase the temperature of the liquid medium and / or generate steam.

[0027] In some embodiments, the flue gas from the flue gas outlet of the cracking furnace is controlled to heat the liquid medium of the steam generating device to increase the temperature of the liquid medium and / or generate steam.

[0028] In some embodiments, the raw material containing 1,2-dichloroethane is controlled to enter a deweighting tower to remove heavy impurities and then enter the compression mechanism.

[0029] In some embodiments, the top pressure of the deweighting tower is controlled to be -20 kPaG ~ 80 kPaG.

[0030] In some embodiments, the 1,2-dichloroethane content in the gas phase at the top outlet of the deweighting tower is controlled to be 98% to 99.99%.

[0031] In some embodiments, part of the gas phase at the top outlet of the de-weighting tower is controlled to enter the compression mechanism, and part of the gas phase is condensed and then refluxed to the de-weighting tower, wherein the ratio of the mass of the gas phase entering the compression mechanism to the mass of the gas phase entering the condensation is 10: (1.5~4.5).

[0032] In some embodiments, the raw material containing 1,2-dichloroethane is controlled to enter the light component removal tower to remove light component impurities and then enter the heavy component removal tower.

[0033] In some embodiments, the feed to the lightness removal column includes 1,2-dichloroethane produced from a chlorination reaction.

[0034] In some embodiments, the 1,2-dichloroethane content in the liquid phase at the bottom outlet of the lightness removal tower is controlled to be no less than 95%.

[0035] In some embodiments, the gas phase pressure at the outlet of the compression mechanism is controlled to be 0.81 MPaG~2.5 MPaG.

[0036] In some embodiments, the pyrolysis gas contains 25% to 50% vinyl chloride, 35% to 60% 1,2-dichloroethane, and 10% to 30% hydrogen chloride.

[0037] The above-mentioned vinyl chloride preparation device can reduce energy consumption and by-products when preparing vinyl chloride through cracking. Compared with the traditional technology in which liquid EDC is vaporized under a certain pressure and enters the cracking furnace for cracking, the steam energy consumption for distillation, the circulating water energy consumption for product condensation and cooling, the steam and other heat source consumption of the EDC vaporizer, and the fuel gas consumption of the cracking furnace, the present application does not require the use of a cooling medium such as circulating water in the traditional technology to condense the gaseous 1,2-dichloroethane extracted from the deweighting tower into a liquid phase. At the same time, before entering the cracking furnace, there is no need to re-pressurize the liquid 1,2-dichloroethane raw material and use high-grade energy such as steam and pyrolysis gas to vaporize it. This can simultaneously save the cooling medium of the refining system and the vaporization heat source of the cracking raw material 1,2-dichloroethane. While reducing energy consumption, the present application can also reduce the production of by-products that may occur due to the pressure increase and vaporization processes of the traditional technology.

[0038] Furthermore, the above-mentioned vinyl chloride preparation device mainly consumes electricity, and can even reach a state of consuming only electricity, which can greatly reduce the amount of cooling medium in the refining system and the vaporization heat source of the cracking raw material 1,2-dichloroethane. At the same time, the heat of the cracking convection section and the thermal cracking gas are recovered separately, which has the effect of significantly reducing the energy consumption of vinyl chloride production and achieving the purpose of reducing costs and increasing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] To more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0040] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings. In the following description, the same reference numerals represent the same parts.

[0041] Figure 1 This is a schematic diagram of a vinyl chloride production device according to an embodiment of the present application;

[0042] Figure 2 This is a schematic flow chart of a method for preparing vinyl chloride according to an embodiment of the present application.

[0043] Description of Reference Numerals

[0044] 10. Vinyl chloride preparation device; 100. Compression mechanism; 200. Cracking furnace; 310. Heat exchange coil; 320. Steam generating equipment; 321. Cold water inlet; 322. Steam outlet; 410. De-weighting tower; 420. De-weighting reboiler; 430. First condensing pipe; 440. First condenser; 450. First reflux storage tank; 460. First reflux pump; 510. De-lighting tower; 520. De-lighting reboiler; 530. Second condensing pipe; 540. Second condenser; 550. Second reflux storage tank; 560. Second reflux pump; 600. Vapor-liquid separator. DETAILED DESCRIPTION

[0045] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0046] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0048] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0049] In the description of this application, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0050] As used herein, "optionally," "optional," and "optional" mean optional, meaning that the option is selected from either of the two parallel options of "with" or "without." If multiple "optional" options appear in a technical solution, each option is independent unless otherwise specified and there are no contradictions or mutual constraints. In this application, expressions such as "optionally contain" and "optionally include" mean "contain or not contain."

[0051] In this article, unless otherwise indicated, each reaction step may be carried out in the order in which it is presented, or may be carried out out of the order in which it is presented. For example, other steps may be included between each reaction step, and the order of the reaction steps may be appropriately reversed. This is something that can be determined by a skilled person based on conventional knowledge and experience. Preferably, the reaction methods described herein are carried out sequentially.

[0052] In this application, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​within the numerical interval is deemed to be continuous and includes the two numerical endpoints of the numerical interval (i.e., the minimum and maximum values), as well as each numerical value between the two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. "Numerical interval" is broadly allowed to include quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0054] The present invention provides a vinyl chloride production device 10 to solve the problem of high energy consumption in the conventional process of producing vinyl chloride by cracking. The vinyl chloride production device 10 will be described below with reference to the accompanying drawings.

[0055] The vinyl chloride preparation device 10 provided in the embodiment of the present application is exemplary, see Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a vinyl chloride production device 10 provided in an embodiment of the present application. The vinyl chloride production device 10 of the present application can be used to produce vinyl chloride, reduce energy consumption, and reduce by-products.

[0056] In order to more clearly illustrate the structure of the vinyl chloride production device 10, the vinyl chloride production device 10 will be introduced below with reference to the accompanying drawings.

[0057] For example, see Figure 1As shown, a vinyl chloride preparation device 10 includes a compression mechanism 100 and a cracking furnace 200. The compression mechanism 100 is used to compress 1,2-dichloroethane to generate high-temperature and high-pressure gaseous 1,2-dichloroethane. The cracking furnace 200 is connected to the compression mechanism 100 to crack the compressed high-temperature and high-pressure gaseous 1,2-dichloroethane to form a cracked gas containing vinyl chloride. It should be noted that the compression mechanism 100 in the present application is used to compress the gaseous 1,2-dichloroethane obtained by distillation. The purpose of this step is to directly separate the gaseous phase at the top of the tower and compress this part of the gaseous phase, eliminating the step of first cooling it to a liquid phase and then gasifying it. Therefore, the compression mechanism 100 obtains high-temperature and high-pressure gaseous 1,2-dichloroethane.

[0058] The above-mentioned vinyl chloride production device 10 can reduce energy consumption and by-products when preparing vinyl chloride through cracking. Compared with the traditional technology in which liquid EDC is vaporized at a certain pressure and enters the cracking furnace for cracking, which requires steam energy consumption for distillation, circulating water energy consumption for product condensation and cooling, heat source consumption such as steam in the EDC vaporizer, and fuel gas consumption in the cracking furnace, the present application does not require the use of a cooling medium such as circulating water in the traditional technology to condense the gaseous 1,2-dichloroethane extracted from the deweighting tower into a liquid phase. At the same time, before entering the cracking furnace, the liquid 1,2-dichloroethane feedstock does not need to be re-pressurized or vaporized using high-grade energy such as steam or pyrolysis gas. This can simultaneously save cooling medium in the refining system and heat source for vaporization of the cracking feedstock 1,2-dichloroethane. While reducing energy consumption, the present application can also reduce the production of by-products that may occur due to the pressure increase and vaporization processes in the traditional technology.

[0059] In some embodiments, the vinyl chloride production apparatus 10 further includes a heat recovery mechanism connected to the cracking furnace 200 for recovering heat from the convection section of the cracking furnace 200 through heat exchange.

[0060] In some embodiments, the heat recovery mechanism includes a heat exchange coil 310. The heat exchange coil 310 is disposed in the cracking furnace 200 to recover heat from the convection section of the cracking furnace 200 through heat exchange, and the liquid inlet and liquid outlet of the heat exchange coil 310 extend to the outside of the cracking furnace 200.

[0061] The above-mentioned vinyl chloride preparation device 10 mainly consumes electric energy, and even reaches a state of consuming only electric energy, which can greatly reduce the amount of cooling medium in the refining system and the vaporization heat source of the cracking raw material 1,2-dichloroethane. At the same time, the heat of the cracking convection section and the cracking gas are recovered separately, which has the effect of significantly reducing the energy consumption of vinyl chloride production and achieving the purpose of reducing costs and increasing efficiency.

[0062] In some embodiments, the heat recovery mechanism further includes a steam generator 320. Optionally, the steam generator 320 includes a cold water inlet 321 and a steam outlet 322. The steam generator 320 is connected to the cracking furnace 200 and communicates with the cracking gas outlet of the cracking furnace 200. The steam generator 320 can utilize the high-temperature cracking gas from the cracking gas outlet to heat the liquid medium to increase the liquid medium temperature and / or generate steam.

[0063] In some embodiments, the steam generating device 320 is also connected to the flue gas outlet of the cracking furnace 200. The steam generating device 320 can use the high-temperature flue gas from the flue gas outlet to heat the liquid medium to increase the liquid medium temperature and / or generate steam.

[0064] In some embodiments, the steam generating device 320 includes a waste heat boiler. A waste heat boiler is a device that uses waste heat generated in industrial processes to generate steam or hot water. This device not only helps to improve energy efficiency but also reduces the impact on the environment. Waste heat boilers are usually installed after industrial processes that require a lot of thermal energy, such as furnaces, kilns, etc., to recover heat from the exhaust gas. The working principle of the waste heat boiler is based on heat exchange technology. It allows liquid media or other working fluids to flow through pipes or channels that are in direct or indirect contact with the hot exhaust gas, thereby absorbing heat from the exhaust gas and heating the working fluid into steam or hot water. This method can effectively recover heat energy that would otherwise be wasted in the atmosphere and convert it into a form of energy that can be used for other production processes or power generation. The use of waste heat boilers in this application can also help reduce the energy costs and carbon emissions of enterprises.

[0065] In some embodiments, the vinyl chloride production apparatus 10 further includes a de-weighting column 410 for removing heavy impurities from the feedstock containing 1,2-dichloroethane. De-weighting column 410 is located upstream of the compression mechanism 100 and is connected to the compression mechanism 100. The top outlet of de-weighting column 410 communicates with the compression mechanism 100 and inputs a gas phase containing 1,2-dichloroethane after the heavy impurities have been removed into the compression mechanism 100.

[0066] In some embodiments, the vinyl chloride production apparatus 10 further includes a de-weighting reboiler 420. The de-weighting reboiler 420 is connected to the bottom of the de-weighting column 410 to reboil the material at the bottom outlet of the de-weighting column 410 and reflux it to the de-weighting column 410.

[0067] In some embodiments, the vinyl chloride preparation device 10 further includes a first condensing pipe 430 connecting the top outlet and the top reflux port of the deweighting tower 410, and a first condenser 440, a first reflux storage tank 450 and a first reflux pump 460 sequentially arranged on the first condensing pipe along the flow direction.

[0068] In some embodiments, the content of 1,2-dichloroethane in the gas phase at the top outlet of the de-weighting tower 410 is 98% to 99.99%.

[0069] In some embodiments, the vinyl chloride production apparatus 10 further includes a vapor-liquid separator 600. The vapor-liquid separator 600 is connected in series between the de-weighting column 410 and the compression mechanism 100 to perform gas-liquid separation on the gas phase at the top outlet of the de-weighting column 410. The gas phase at the top outlet of the de-weighting column 410 contains some liquid. The use of the vapor-liquid separator 600 can minimize the amount of liquid mixed in the gas phase and increase the proportion of 1,2-dichloroethane in the gas phase at the top outlet of the de-weighting column 410.

[0070] In some embodiments, the vinyl chloride production apparatus 10 further includes a light-removal column 510 for removing light impurities from the feedstock containing 1,2-dichloroethane. The light-removal column 510 is located upstream of and connected to the heavy-removal column 410. The feed inlet of the light-removal column 510 communicates with the bottom outlet of the heavy-removal column 410.

[0071] In some embodiments, the vinyl chloride production apparatus 10 further includes a light removal reboiler 520. The light removal reboiler 520 is connected to the bottom of the light removal column 510 to reboil the material at the bottom outlet of the light removal column 510 and reflux it to the light removal column 510.

[0072] In some embodiments, the vinyl chloride preparation device 10 also includes a second condensing pipe 530 connecting the top outlet of the light removal tower 510 and the light removal reflux port of the tower, and a second condenser 540, a second reflux storage tank 550 and a second reflux pump 560 arranged sequentially on the second condensing pipe along the flow direction.

[0073] In some embodiments, the light fraction removal column 510 includes a distillation column capable of separating light component impurities including hydrogen chloride and carbon tetrachloride.

[0074] In some embodiments, the feed to the lightness removal column 510 includes 1,2-dichloroethane produced from the chlorination reaction.

[0075] In some embodiments, the content of 1,2-dichloroethane in the liquid phase at the bottom outlet of the lightness removal tower 510 is not less than 95%.

[0076] An embodiment of the present application also provides a method for preparing vinyl chloride.

[0077] See also Figure 2 As shown, Figure 2 This is a flow chart of a method for preparing vinyl chloride according to an embodiment of the present application. The method for preparing vinyl chloride, using the vinyl chloride preparation device 10 in any of the above embodiments, comprises the following steps:

[0078] S10, controlling 1,2-dichloroethane to enter the compression mechanism 100 and be compressed into a high-temperature and high-pressure gas phase.

[0079] S20, controlling the cracking furnace 200 to crack the compressed high-temperature and high-pressure 1,2-dichloroethane to form a cracking gas containing vinyl chloride.

[0080] In some embodiments, a heat recovery mechanism connected to the cracking furnace 200 is controlled to recover heat from a convection section within the cracking furnace 200 through heat exchange.

[0081] In some embodiments, the heat exchange coil 310 disposed in the cracking furnace 200 is controlled to perform heat exchange and recovery on the convection section of the cracking furnace 200 .

[0082] In some embodiments, the heat exchange medium in the heat exchange coil 310 includes one or more of boiler water, steam, air, fuel gas, and 1,2-dichloroethane, wherein the boiler water is deoxygenated boiler water.

[0083] In some embodiments, the cracked gas from the cracked gas outlet of the cracking furnace 200 is controlled to heat the liquid medium of the steam generating device 320 to increase the temperature of the liquid medium and / or generate steam.

[0084] In some embodiments, the flue gas at the flue gas outlet of the cracking furnace 200 is controlled to heat the liquid medium of the steam generating device 320 to increase the temperature of the liquid medium and / or generate steam.

[0085] In some embodiments, the liquid medium may be cold water.

[0086] In some embodiments, the raw material containing 1,2-dichloroethane is controlled to enter the deweighting tower 410 to remove heavy impurities and then enter the compression mechanism 100.

[0087] In some embodiments, the top pressure of the deweighting tower 410 is controlled to be -20 kPaG to 80 kPaG.

[0088] In some embodiments, the 1,2-dichloroethane content in the gas phase at the top outlet of the de-weighting tower 410 is controlled to be 98% to 99.99%.

[0089] In some embodiments, a portion of the gas phase at the top outlet of the de-weighting tower 410 is controlled to enter the compression mechanism 100, and a portion of the gas phase is condensed and then refluxed to the de-weighting tower 410, wherein the mass ratio of the gas phase entering the compression mechanism 100 to the mass ratio of the gas phase entering the condenser is 10:(1.5-4.5). For example, the mass ratio of the gas phase entering the compression mechanism 100 to the mass ratio of the gas phase entering the condenser is 10:1.5; for another example, the mass ratio of the gas phase entering the compression mechanism 100 to the mass ratio of the gas phase entering the condenser is 10:4.5.

[0090] In some embodiments, the raw material containing 1,2-dichloroethane is controlled to enter the light component removal column 510 to remove light component impurities and then enter the heavy component removal column 410.

[0091] In some embodiments, the feed to the lightness removal column 510 includes 1,2-dichloroethane produced from the chlorination reaction.

[0092] In some embodiments, the 1,2-dichloroethane content in the liquid phase at the bottom outlet of the lightness removal tower 510 is controlled to be no less than 95%.

[0093] In some embodiments, the gas phase pressure at the outlet of the compression mechanism 100 is controlled to be 0.81 MPaG~2.5 MPaG.

[0094] In some embodiments, the cracking gas prepared in the present application has a vinyl chloride content of 25% to 50%, a 1,2-dichloroethane content of 35% to 60%, and a hydrogen chloride content of 10% to 30%.

[0095] In one embodiment, see Figure 1 As shown, the vinyl chloride production apparatus 10 includes a light-removal column 510, a heavy-removal column 410, a vapor-liquid separator 600, a compression mechanism 100, a cracking furnace 200, and a steam generator 320, which are connected in sequence. A light-removal reboiler 520 is connected to the bottom of the light-removal column 510 to reboil the material at the bottom outlet of the light-removal column 510 and reflux it back to the light-removal column 510. A second condensing line 530 is connected between the top outlet of the light-removal column 510 and the light-removal reflux port of the light-removal column 510. The second condensing line 530 is provided with a second condenser 540, a second reflux tank 550, and a second reflux pump 560, which are sequentially arranged on the second condensing line along the flow direction. The bottom outlet of the light-removal column 510 is connected to the feed port of the heavy-removal column 410. A heavy-removal reboiler 420 is connected to the bottom of the heavy-removal column 410 to reboil the material at the bottom outlet of the heavy-removal column 410 and reflux it back to the heavy-removal column 410. A first condensing pipe 430 is connected between the top outlet and the top reflux port of the deweighting tower 410; the first condensing pipe 430 is provided with a first condenser 440, a first reflux storage tank 450 and a first reflux pump 460 which are sequentially arranged on the first condensing pipe along the flow direction.

[0096] In one embodiment, a method for preparing vinyl chloride uses Figure 1 The vinyl chloride preparation device 10 comprises the following steps:

[0097] S11. Control the feedstock (F2) containing 1,2-dichloroethane to enter the light component removal column 510 to remove light component impurities. The feedstock (F2) to the light component removal column 510 includes 1,2-dichloroethane produced by the chlorination reaction. The 1,2-dichloroethane content in the liquid phase at the bottom outlet of the light component removal column 510 is not less than 95%.

[0098] S21. Control the feedstock containing 1,2-dichloroethane at the bottom outlet of light-removal column 510, or add feedstock (F1) from which carbon tetrachloride, water, and other impurities have been removed, to enter heavy-removal column 410 to remove heavy impurities (P1). Control the pressure at the top of heavy-removal column 410 between -20 kPaG and 80 kPaG. The 1,2-dichloroethane content in the gas phase at the top outlet of heavy-removal column 410 is between 98% and 99.99%.

[0099] S31. Control part of the gas phase (compressed stream, S2) at the top outlet of the deweighting tower 410 to enter the compression mechanism 100, and part of the gas phase (reflux stream, S1) is condensed and then refluxed to the deweighting tower 410; the ratio of the mass of the gas phase entering the compression mechanism 100 to the mass of the gas phase entering the condensation is 1:(1.5~4.5).

[0100] S41 , part of the gas phase ( S2 ) passes through the gas-liquid separator 600 to separate and remove the liquid phase ( P3 ) and then enters the compression mechanism 100 .

[0101] S51: Control the compression mechanism 100 to compress the raw material containing 1,2-dichloroethane. Control the gas phase pressure at the outlet of the compression mechanism 100 to be 0.81 MPaG to 2 MPaG.

[0102] S61. Fuel gas (F4) is burned to provide heat for cracking furnace 200, which is then controlled to crack compressed 1,2-dichloroethane or 1,2-dichloroethane gas (F3) added from a backup pipeline to produce cracking gas containing vinyl chloride. The cracking gas contains 25% to 50% vinyl chloride, 35% to 60% 1,2-dichloroethane, and 10% to 30% hydrogen chloride.

[0103] S71. Control heat exchange coil 310 within cracking furnace 200 to perform heat exchange and recovery on the convection section within cracking furnace 200. The heat exchange medium (F5) within heat exchange coil 310 includes one or more of deoxygenated boiler water, steam, air, fuel gas, and 1,2-dichloroethane, forming heat medium (P5) after heat exchange.

[0104] S81. Control the cracked gas (P4) from the cracked gas outlet of the cracking furnace 200 to heat the cold water (F6) of the steam generator 320 to generate steam (S3). Flue gas (G) from the flue gas outlet is introduced into the steam generator 320 to heat the cold water of the steam generator 320 to generate steam.

[0105] Example 1

[0106] This embodiment provides a method of using the above Figure 1 The vinyl chloride preparation method in the exemplary embodiment is used to prepare vinyl chloride (VCM) with an annual output of 30 wt (10,000 tons).

[0107] The 1,2-dichloroethane (F2) containing hydrogen chloride is treated with a light removal tower 510 to remove the hydrogen chloride component. The material at the bottom outlet of the light removal tower 510 is mixed with the material (F1, see attached) which has been previously freed of impurities such as carbon tetrachloride and water. Figure 1 As shown) together as the feed of the deweighting tower 410.

[0108] The tower pressure of the deweighting tower 410 is controlled to be 50 kPaG, the tower top temperature of the deweighting tower 410 is about 97°C, the content of 1,2-dichloroethane in the tower top gas phase of the deweighting tower 410 is 99.5 wt%, and the top extraction of the deweighting tower 410 is divided into a reflux stream (S1) and a compression stream (S2), and the reflux stream flow rate is about 38 t / h (tons / hour); the compression stream flow rate is about 100 t / h.

[0109] The reflux stream is condensed by the refrigerant circulating water in the first condenser 440 to obtain liquid 1,2-dichloroethane, which is then pumped back to the de-weighting column 410 by the first reflux pump 460 .

[0110] After the compressed stream passes through the vapor-liquid separator 600 to separate and remove the liquid phase, it is compressed to 1.3 MPaG using the compression mechanism 100 and then enters the cracking furnace. The fuel gas (F4) is burned to provide heat for the cracking furnace 200. The radiation section of the cracking furnace cracks the gas to obtain a cracking gas (P4) with a temperature of about 450°C.

[0111] The heat of the cracked gas (P4) is used to heat the cold water of the steam (F6) generating equipment to produce medium-pressure steam (S3).

[0112] The convection section of the cracking furnace is equipped with two heat extraction sections. One section is used by heat exchange coil 310 to heat cold air (F5), raising the air temperature in the cracking furnace to 175°C hot air (P5). The other section is used by heat exchange coil 310 to heat boiler water to produce medium-pressure steam. Flue gas (G) from the flue gas outlet is introduced into the steam generator 320 to heat the cold water in the steam generator 320 to produce steam.

[0113] After testing, the cracking gas prepared in this example contained 34.5% vinyl chloride, 45% 1,2-dichloroethane, and 20% hydrogen chloride.

[0114] Comparative Example 1

[0115] This comparative example provides a method for preparing vinyl chloride, which can produce 30 wt (10,000 tons) of vinyl chloride (VCM) per year.

[0116] The comparative example uses a conventional method, i.e., crude 1,2-dichloroethane (EDC) is distilled to obtain a refined 1,2-dichloroethane product suitable for cracking. The refined 1,2-dichloroethane product is condensed and liquefied, and the liquid 1,2-dichloroethane is vaporized under a certain pressure using an EDC vaporizer. The vaporized 1,2-dichloroethane is then fed into a cracking furnace for cracking. Specifically, the following steps are included:

[0117] The de-weighting tower 410 is used to treat 1,2-dichloroethane. The tower pressure of the de-weighting tower 410 is controlled at 50 kPaG, corresponding to a tower top temperature of approximately 97°C. The content of 1,2-dichloroethane in the tower top gas phase of the de-weighting tower 410 is 99.5 wt%. The tower top gas phase of the de-weighting tower 410 is completely condensed and liquefied. After the 1,2-dichloroethane is cooled to 40°C, the tower top of the de-weighting tower 410 is extracted and divided into a reflux stream (S1) and a compression stream (S2). The reflux stream flow rate is approximately 38 t / h; the compression stream flow rate is approximately 100 t / h.

[0118] The liquid phase 1,2-dichloroethane of the compressed stream is sent to the intermediate storage tank. At this time, the temperature of the compressed stream is about 30°C, and it is transported to the cracking furnace and preheated to 190°C through the convection section. The heated 1,2-dichloroethane enters the EDC vaporizer and controls the vaporization pressure to be 1.3 MPaG to obtain the cracking raw material gas phase 1,2-dichloroethane. The EDC vaporizer is provided with heat source by heat exchange condensation of medium-pressure steam, and the medium-pressure steam is obtained by heat exchange of thermal cracking gas after cracking the raw material. The gas phase 1,2-dichloroethane enters the cracking furnace for cracking to obtain the cracking product vinyl chloride.

[0119] The parameters of Example 1 and Comparative Example 1 are compared and shown in Table 1.

[0120] Table 1 Parameters of Example 1 and Comparative Example 1

[0121]

[0122] As shown in Table 1, when the utility usage of Comparative Example 1 and Example 1 is the same, the operating cost of Example 1 can be reduced by 80 yuan / tVCM to 90 yuan / tVCM compared with Comparative Example 1.

[0123] In the present application, a 1,2-dichloroethane product that meets cracking indicators and is suitable for compression is obtained through front-end processing including light and heavy removal. Gas-phase 1,2-dichloroethane of a specified temperature and pressure suitable for thermal cracking is directly obtained through compression. Only a portion of electrical energy is consumed in the compression process, and there is no need to use a cooling medium such as circulating water to condense the gas-phase 1,2-dichloroethane produced from the deweighting tower 410 into a liquid phase as in traditional technologies. At the same time, before entering the cracking furnace, the liquid-phase 1,2-dichloroethane raw material does not need to be re-pressurized or vaporized using high-grade energy such as steam or pyrolysis gas, which can save both the cooling medium of the refining system and the vaporization heat source of the cracking raw material 1,2-dichloroethane. The heat of the convection section and the pyrolysis gas after cracking can be recovered by the heat exchange medium and the steam generation device 320 such as a boiler after producing steam, thereby reducing system fuel consumption, or sent as net heat production to other devices, reducing production costs and improving energy utilization.

[0124] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0125] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0126] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A vinyl chloride production device, characterized in that: include: A compression mechanism for compressing 1,2-dichloroethane to generate a gaseous phase; and a cracking furnace connected to the compression mechanism to crack the compressed gas phase 1,2-dichloroethane to form cracked gas containing vinyl chloride.

2. The vinyl chloride production device according to claim 1, characterized in that: The vinyl chloride production device further includes a heat recovery mechanism connected to the cracking furnace for recovering heat from the convection section of the cracking furnace through heat exchange. Optionally, the heat recovery mechanism includes a heat exchange coil, which is arranged in the cracking furnace to perform heat exchange and recovery on the convection section heat in the cracking furnace.

3. The vinyl chloride production device according to claim 2, characterized in that: The heat recovery mechanism also includes a steam generating device, which is connected to the cracking furnace and communicates with the cracking gas outlet of the cracking furnace. The steam generating device can use the cracking gas from the cracking gas outlet to heat the liquid medium to increase the liquid medium temperature and / or generate steam.

4. The vinyl chloride production device according to claim 3, characterized in that: The steam generating device is also in communication with the flue gas outlet of the cracking furnace. The steam generating device can utilize the flue gas from the flue gas outlet to heat the liquid phase medium to increase the temperature of the liquid phase medium and / or generate steam.

5. The vinyl chloride production device according to any one of claims 1 to 4, characterized in that: The vinyl chloride preparation device also includes a deweighting tower for removing heavy impurities from the raw material containing 1,2-dichloroethane. The deweighting tower is located upstream of the compression mechanism. The top outlet of the deweighting tower is connected to the compression mechanism and inputs the gas phase containing 1,2-dichloroethane after the heavy impurities are removed into the compression mechanism.

6. The vinyl chloride production device according to claim 5, characterized in that: The vinyl chloride preparation device further includes a de-weighting reboiler, which is connected to the bottom of the de-weighting tower to reboil the material at the bottom outlet of the de-weighting tower and reflux it to the de-weighting tower; And / or, the vinyl chloride production device further comprises a first condensing pipe connecting the top outlet and the top reflux port of the deweighting tower, and a first condenser, a first reflux storage tank and a first reflux pump sequentially arranged on the first condensing pipe along the flow direction; And / or, the vinyl chloride production device further includes a vapor-liquid separator, which is connected in series between the deweighting tower and the compression mechanism to perform gas-liquid separation on the gas phase at the top outlet of the deweighting tower.

7. The vinyl chloride production device according to claim 5, characterized in that: The vinyl chloride preparation device also includes a light-removing tower for removing light component impurities from a raw material containing 1,2-dichloroethane. The light-removing tower is located upstream of the heavy-removing tower and connected to the heavy-removing tower. The bottom outlet of the light-removing tower is connected to the feed inlet of the heavy-removing tower.

8. The vinyl chloride production device according to claim 7, characterized in that: The vinyl chloride preparation device further includes a light removal reboiler, which is connected to the bottom of the light removal tower to reboil the material at the bottom outlet of the light removal tower and reflux it to the light removal tower; And / or, the vinyl chloride production device further comprises a second condensing pipe communicating with the top outlet of the light removal column and the light removal reflux port of the light removal column, and a second condenser, a second reflux storage tank and a second reflux pump sequentially arranged on the second condensing pipe along the flow direction; And / or, the light-removal tower comprises a distillation tower capable of separating light component impurities containing hydrogen chloride and carbon tetrachloride.

9. A method for preparing vinyl chloride, characterized in that: The steps include: Controlling the compression mechanism to compress 1,2-dichloroethane into a gas phase; and controlling the cracking furnace to crack the compressed gas phase 1,2-dichloroethane to form cracked gas containing vinyl chloride.

10. The method for preparing vinyl chloride according to claim 9, characterized in that: The method for preparing vinyl chloride further satisfies at least one of the following conditions: (1) controlling a heat recovery mechanism connected to the cracking furnace to perform heat exchange and recovery on the convection section of the cracking furnace; Optionally, the heat exchange medium in the heat exchange coil includes one or more of boiler water, steam, air, fuel gas and 1,2-dichloroethane; (2) controlling the cracked gas from the cracked gas outlet of the cracking furnace to heat the liquid phase medium of the steam generating device to increase the temperature of the liquid phase medium and / or generate steam; (3) controlling the flue gas from the flue gas outlet of the cracking furnace to heat the liquid phase medium of the steam generating device to increase the temperature of the liquid phase medium and / or generate steam; (4) Controlling the raw material containing 1,2-dichloroethane to enter the deweighting tower to remove heavy component impurities and then enter the compression mechanism; Optionally, the top pressure of the deweighting tower is controlled to be -20 kPaG~80 kPaG; Optionally, the 1,2-dichloroethane content in the gas phase at the top outlet of the deweighting tower is controlled to be 98% to 99.99%; Optionally, part of the gas phase at the top outlet of the de-weighting tower is controlled to enter the compression mechanism, and part of the gas phase is condensed and then refluxed to the de-weighting tower, wherein the mass ratio of the gas phase entering the compression mechanism to the mass of the gas phase entering the condensation is 10:(1.5-4.5); (5) Controlling the raw material containing 1,2-dichloroethane to enter the light removal tower to remove light component impurities and then enter the heavy removal tower; (6) The gas phase pressure at the outlet of the compression mechanism is controlled to be 0.81 MPaG~2.5 MPaG.

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