Process and apparatus for removing wax from methanol and recovering the same

Abstract

The application discloses a method and device for removing wax in methanol and recovering and enriching the methanol. The device comprises a steam turbine, a compressor, a heat exchanger, a filter, a wax remover and an evaporator. The wax remover comprises three working modes of temperature reduction, low-temperature adsorption and temperature increase for wax removal. The steam turbine is used for compressing refrigerant and reducing the temperature of liquid-phase methanol containing wax, so that the wax is precipitated and adhered to the wax remover. The turbine exhaust steam is used for heating and removing the wax and recovering and enriching the wax. The application plays a positive role in greatly reducing the impurity content in methanol raw materials, reducing the cleaning frequency and the start-stop frequency of various types of equipment and preventing production fluctuation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of methanol dewaxing, in particular to a method and device for removing wax from methanol and enriching and recycling. BACKGROUND

[0002] Methanol is an important raw material in the chemical industry, which is widely used in coal chemical industry, methanol chemical industry and methanol to hydrocarbon process and other fields. It is also an important raw material for producing hydrocarbons by replacing other resources instead of oil.

[0003] At present, the methanol produced by various processes contains a certain amount of long carbon chain (C5-C 45 ) fatty alcohols, which are also called "wax" or "paraffin wax" in industry. The wax will inevitably adhere to the inside of the equipment when the raw material methanol enters the subsequent production process due to the decrease in temperature, which may have many negative effects, such as clogging the raw material heat exchange system, reducing the quality of raw materials, clogging the catalyst pores in the fluidized bed reactor, reducing the reaction efficiency or conversion rate, clogging the trays when entering the water system, increasing the sewage treatment load, etc. In severe cases, it may cause production fluctuations or even need to stop for cleaning, resulting in unnecessary operation and maintenance costs.

[0004] Traditional online dewaxing methods mostly use rectification or steam blowing methods. Such methods mostly need to use porcelain balls and other fillers. Although porcelain balls and other fillers have the characteristics of large adsorption area, the synthetic catalyst will inevitably be broken during long-term use, and its fine powder can easily clog the pores. In addition, long-term repeated blowing and frequent regeneration lead to the breakage of porcelain balls and other fillers, and the blowing is not complete and thorough, which needs to be replaced regularly, affecting the continuous operation of the device. In addition, the wax can be further processed in other chemical fields to produce necessary raw materials for light chemical industry and other industries, thereby increasing the added value. However, using steam heating to blow and condense the wax will introduce new media and not enrich the fatty alcohols, thereby increasing the difficulty of recovering the wax in methanol. SUMMARY

[0005] Therefore, the main purpose of the present application is to provide a method and device for removing wax from methanol and enriching and recycling, which can greatly reduce the impurity content in the methanol raw material and is simple to operate.

[0006] To achieve the above-mentioned application purposes, the present application adopts the following technical solutions: a device for removing wax from methanol and enriching and recycling, comprising:

[0007] A steam turbine is in communication with an external steam source, has a turbine exhaust steam outlet and an outlet in communication with the compressor;

[0008] a compressor, which is in communication with and driven by the outlet of the steam turbine, has a gas-phase refrigerant inlet and a compressed medium outlet;

[0009] a heat exchanger, which is in communication with and exchanges heat with the medium outlet of the compressor, has a liquid-phase refrigerant outlet;

[0010] a filter, which is in communication with the wax-containing methanol main pipe for filtering particles in the wax-containing methanol, has an outlet in communication with the wax remover;

[0011] a wax remover, which has a first cooling inlet in communication with the liquid-phase refrigerant outlet of the heat exchanger, a wax-containing methanol inlet in communication with the outlet of the filter, a hot turbine exhaust inlet in communication with the heated turbine exhaust, and has a liquefied wax outlet and a clean methanol outlet;

[0012] an evaporator, which is in communication with the liquefied wax outlet of the wax remover for evaporating and removing residual methanol in the liquefied wax.

[0013] According to the device of the present application, the turbine exhaust outlet of the steam turbine is divided into two branches, the first branch being the heated turbine exhaust and the second branch being the bypass turbine exhaust. Preferably, the above-mentioned branches can be realized by a three-way valve at the turbine exhaust outlet.

[0014] According to the device of the present application, the wax remover further has a first cooling outlet in communication with the gas-phase refrigerant inlet of the compressor.

[0015] According to the device of the present application, the wax remover further has a cold turbine exhaust outlet in communication with the bypass turbine exhaust, and preferably, the cold turbine exhaust discharged from the wax remover through the outlet can be collected into a pipeline.

[0016] According to the device of the present application, the wax remover is further provided with a liquid level meter for measuring the liquid level between the maximum volume point and the lowest point of the body of the wax remover.

[0017] According to the device of the present application, the wax remover can be provided with one to multiple devices, for example, 1-3 devices, according to the actual needs such as standby condition, methanol flow, wax removal efficiency, etc., and the multiple devices are sequentially operated.

[0018] According to the device of the application, the first cooling inlet and the first cooling outlet are communicated as a first pipeline inside the wax remover, the hot turbine exhaust inlet and the cold turbine exhaust outlet are communicated as a second pipeline, and the first pipeline or the second pipeline can adopt one or more of the following arrangement forms inside the wax remover: conjugate, parallel, vertical, parallel, winding, etc. A plurality of forms of fins, wire meshes, internal filters, etc. can be arranged in the space between the outer walls of the first pipeline between the first cooling inlet and the first cooling outlet and the outer walls of the second pipeline between the hot turbine exhaust inlet and the cold turbine exhaust inlet, so as to increase the heat exchange area and effectively intercept the wax condensed at low temperature. In the process of wax cooling, the wax will undergo the process of "separation from methanol - volume increase - stripping by liquid", and the internal filter is used to filter large particles and desorbed solid wax.

[0019] According to the device of the application, the evaporator has an evaporation gas inlet and a distributor, a solid wax discharge outlet, a waste gas outlet, a wax discharge degassing bin and a liquefied wax inlet communicated with the liquefied wax outlet of the wax remover.

[0020] According to the device of the application, a heating device is arranged at the bottom of the wax remover, the liquefied wax outlet of the wax remover and the liquefied wax inlet of the evaporator, and the heating temperature is greater than 125 DEG C, so as to ensure smooth flow of the liquefied wax. The heating form can be any one of electric heating and steam heating.

[0021] The application further provides a method for removing wax from methanol and recovering and enriching, which comprises the following steps:

[0022] 1) The low-pressure steam is used to drive the turbine in the steam turbine, and the compressor is driven to compress the refrigerant. The compressed refrigerant is cooled by the heat exchanger, and then enters the wax remover to cool the internal accessories. The wax remover enters the cooling mode.

[0023] 2) The methanol containing wax is filtered to remove particles, and then enters the wax remover to contact the cooled accessories. The dissolved fatty alcohol in the methanol is separated and adhered to the internal accessories. The wax remover enters the low-temperature adsorption mode, and the clean methanol is discharged from the wax remover.

[0024] 3) When the wax remover is saturated with adsorbed wax, the heated turbine exhaust is introduced into the wax remover, and the wax remover enters the temperature rising and wax discharging mode. The wax adhered to the internal accessories of the wax remover is liquefied due to high temperature, and the liquefied wax containing residual methanol is obtained.

[0025] 4) The liquefied wax is discharged into the evaporator for treatment, and the gas phase and solid wax are obtained.

[0026] Wherein, the steps 1) to 3) are cycled in the wax remover.

[0027] According to the method of the present application, the working temperature range of the wax remover is -35-164℃, and according to the temperature range, the wax remover is divided into three working modes of temperature reduction, low-temperature adsorption and temperature increase for wax removal. Preferably, when multiple wax removers are arranged, the temperature reduction, low-temperature adsorption and temperature increase for wax removal procedures can be set from any one according to actual needs and the automatic switching mode is set to run in the above sequence in multiple wax removers. For example, the wax removers A, B and C enter the temperature reduction-low-temperature adsorption-temperature increase for wax removal procedures in sequence, when the wax remover A enters the low-temperature adsorption mode, the wax remover B is controlled by the sequence controller to repeat the steps of the wax remover A, so that the wax remover B enters the temperature reduction mode, and the like.

[0028] According to the method of the present application, in step 1), when the wax remover is in the temperature reduction mode, all turbine exhaust steam in the steam turbine enters the second branch, i.e. bypass turbine exhaust steam.

[0029] According to the method of the present application, in step 1), the temperature reduction mode of the wax remover can be manually set to start according to actual needs, or start after the wax removal of a certain wax remover in the wax remover group is completed during the temperature increase for wax removal procedure; specifically, when the liquefied wax outlet of a wax remover no longer receives liquefied wax, or when the temperature of the cold turbine exhaust steam outlet is higher than 152℃ and maintains for more than 15 min, the cold turbine exhaust steam outlet is exhausted to prevent freezing, the liquefied wax outlet is closed, the first cooling inlet and the first cooling outlet are opened, and the wax remover enters the temperature reduction mode.

[0030] According to the method of the present application, in step 2), the start of the low-temperature adsorption mode of the wax remover can be set according to the temperature of the first cooling outlet; specifically, when the temperature is reduced to -28℃, the wax-containing methanol inlet is opened, when the liquid level meter reaches the maximum value, the clean methanol outlet is opened and the flow rate is controlled to maintain the maximum value of the liquid level meter, and the wax remover enters the low-temperature adsorption mode. During the low-temperature adsorption, the temperature of the corresponding first cooling outlet is not higher than -22℃.

[0031] According to the method of the present application, in step 3), the start of the temperature increase for wax removal mode of the wax remover can be set according to the pressure difference between the wax-containing methanol inlet and the clean methanol outlet, or the temperature of the first cooling outlet; specifically, when the pressure difference is higher than 0.06 MPa, or the temperature of the corresponding first cooling outlet is lower than -32℃, it is considered that the low-temperature adsorption wax amount of the wax remover is saturated, all liquid-phase clean methanol in the wax remover is exhausted by closing the wax-containing methanol inlet and keeping the clean methanol outlet open, and the first cooling inlet is closed. When the liquid level of the liquid level meter is 0%, the clean methanol outlet is closed, the first cooling outlet is opened, the hot turbine exhaust steam inlet and the cold turbine exhaust steam outlet are opened, and the wax remover enters the temperature increase for wax removal mode.

[0032] The opening, closing and flow control of the inlet or outlet described herein can be achieved in an automatic control mode by setting a controller, which is set as prior art and will not be described again.

[0033] The present application provides a process and method for compressing refrigerant by steam turbine and cooling liquid-phase waxy methanol to make wax precipitate and adhere in a wax remover, heating the wax by turbine exhaust steam and recovering and enriching wax, which has the following advantages compared with prior art.

[0034] (1) According to the feature that the dissolved fatty alcohol in methanol can precipitate at low temperature, the present application sets a steam turbine and a compressor, uses steam to drive the compressor to compress refrigerant, and the low-temperature medium at the outlet of the compressor expands in the wax remover to fully cool the methanol. Although the wax in methanol has a great impact on production, considering that the total amount of wax is relatively low compared with methanol, a plurality of forms of fins, wire mesh, filters, etc. can be set on the outer wall of the low-temperature medium pipeline in the wax remover by winding, inlaying or other ways, which can not only increase the heat exchange area, but also effectively intercept the wax condensed at low temperature.

[0035] (2) The turbine exhaust steam of the present application can be used as a heat source for wax removal. The pipeline in the wax remover is conjugated with the low-temperature medium pipeline and uses the same outer wall to set a plurality of forms of fins, wire mesh, filters, etc. by winding or inlaying, which exchanges heat with the wax condensed thereon. The condensed wax is liquefied and can be discharged from the bottom of the wax remover, and the residual methanol in the liquefied wax is separated again in the evaporator and recovered as wax and methanol, thereby solving the problem of difficult separation of wax in methanol. During this period, the waste heat of the turbine exhaust steam can be recovered, and the evaporation medium in the evaporator can be sent to the flare. The steam exhaust steam after recycling the turbine compressed refrigerant can be used as an indirect heating medium for precipitating wax.

[0036] (3) The wax remover of the present application can be provided with one or more, which can be automatically controlled in sequence by setting parameters such as pressure difference, temperature, running time, etc. to ensure that the system cooling, feed condensation and heating wax removal of the wax remover proceed smoothly.

[0037] In summary, the present application plays a positive role in greatly reducing the impurity content in methanol raw materials, reducing the cleaning frequency and start-stop frequency of various equipment, and preventing production fluctuations. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A schematic diagram of an apparatus for removing wax from methanol and enriching recovery.

[0039] Figure 2 A schematic diagram of a method flow for removing wax from methanol and enriching recovery.

[0040] The reference signs are as follows: steam turbine 1, compressor 2, heat exchanger 3, steam inlet 4, turbine exhaust outlet 5, three-way valve 6, bypass turbine exhaust 7, wax remover A / B / C (8 / 9 / 10), wax-containing methanol main pipe 11, liquid-phase refrigerant outlet 12, clean methanol tank inlet 13, heated turbine exhaust 14, cold exhaust manifold 15, gas-phase refrigerant inlet 16, liquefied wax inlet 17, filter 18, evaporator 19, evaporated gas inlet and distributor 20, solid wax discharge outlet 21, exhaust gas outlet 22, wax removal degassing bin 23, waste liquid discharge outlet 24;

[0041] The wax remover A / B / C (8 / 9 / 10) comprises: liquid level meter (81 / 91 / 101), nitrogen purger (82 / 92 / 102), back-flushing hot nitrogen gas inlet (84 / 94 / 104), wax-containing methanol inlet A / B / C (111 / 112 / 113), first cooling inlet A / B / C (121 / 122 / 123), clean methanol outlet A / B / C (131 / 132 / 133), hot turbine exhaust inlet A / B / C (141 / 142 / 143), cold turbine exhaust outlet (151 / 152 / 153), first cooling outlet A / B / C (161 / 162 / 163), and liquefied wax outlet A / B / C (171 / 172 / 173). DETAILED DESCRIPTION

[0042] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0043] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0044] Unless otherwise defined, the terms "mounting", "connected", "connecting", "fixed", "fixing" should be construed as broad, for example, can be fixed connection, can also be detachable connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] The main idea of the present application is to provide a method for removing wax from methanol and enriching and recovering, using steam turbine to compress the refrigerant and cooling the liquid phase wax-containing methanol, so that the wax is precipitated and adheres to the wax remover, the turbine exhaust steam is used to heat and remove the wax, further, the evaporator is used to evaporate and remove the residual methanol in the liquefied wax, and the wax and methanol are recovered respectively.

[0046] Based on this, the device for removing wax from methanol and enriching and recovering in the embodiment of the present application mainly comprises:

[0047] The steam turbine is in communication with an external steam source, has a turbine exhaust steam outlet and a steam outlet in communication with the compressor;

[0048] The compressor is in communication with the steam outlet of the steam turbine and is driven thereby, has a gas phase refrigerant inlet and a compressed medium outlet;

[0049] The heat exchanger is in communication with the medium outlet of the compressor and exchanges heat with it, has a liquid phase refrigerant outlet;

[0050] The filter is in communication with the wax-containing methanol main pipe for filtering particles in the wax-containing methanol, has an outlet in communication with the wax remover;

[0051] The wax remover has a first cooling inlet in communication with the liquid phase refrigerant outlet of the heat exchanger, a wax-containing methanol inlet in communication with the outlet of the filter, a hot turbine exhaust steam inlet in communication with the heated turbine exhaust steam, and further has a liquefied wax outlet, a clean methanol outlet and a cold turbine exhaust steam outlet;

[0052] The evaporator is in communication with the liquefied wax outlet of the wax remover for evaporating and removing residual methanol in the liquefied wax.

[0053] As shown in the following, the structure and parameters of each device are described in detail with the drawings as examples. Figures 1-2

[0054] The steam turbine 1 has a steam inlet 4 in communication with an external steam source, a turbine exhaust steam outlet 5, and the turbine exhaust steam outlet 5 is divided into two branches, the first branch is the heated turbine exhaust steam 14, and the second branch is the bypass turbine exhaust steam 7.

[0055] ​Preferably, the above-mentioned branch can be realized by a three-way valve 6 at the outlet of the turbine exhaust steam. Further, the three-way valve 6 can automatically control the flow according to different operation modes of the wax removers or different flow requirements of the hot turbine exhaust steam, or manually set the distribution of the turbine exhaust steam flow to the heating turbine exhaust steam 14 and the bypass turbine exhaust steam 7 respectively in addition to the above-mentioned operation modes.

[0056] Preferably, the driving medium in the steam turbine 1 is water vapor, the pressure range is 0.44-4.3 MPa, and the steam flow range is 40-150 t / h.

[0057] The compressor 2 driven by the above-mentioned steam turbine 1 has a gas-phase refrigerant inlet 16. Preferably, the refrigerant medium used in the compressor 2 can be one or more of ammonia, methanol, hydrogen, alkane, freon, and carbon dioxide, and the form of the compressor 2 should not be limited to any stage compression refrigeration by the schematic diagram or example.

[0058] The heat exchanger 3 connected to the outlet of the compressor 2 has a liquid-phase refrigerant outlet 12. Preferably, the cooling medium of the heat exchanger 3 can be one or more of clean air, methanol, hydrogen, alkane, freon, and carbon dioxide, and the heat exchanger can be used between each stage of the compressor 2.

[0059] The filter 18, the inlet of which is communicated with the wax-containing methanol main pipe 11, is used to remove the broken fine powder of the synthesis catalyst, such as filtering out particles with a diameter of 10 μm or more.

[0060] The wax removers, the number of which can be increased by one to several according to actual needs such as standby, methanol flow, and wax removal efficiency, for example, three wax removers A / B / C (8 / 9 / 10) shown in the drawing, wherein " / " represents "or", i.e. wax remover A 8, wax remover B 9, and wax remover C 10. For the sake of simple expression, the corresponding components in the following wax remover A 8, wax remover B 9, and wax remover C 10 are separated by " / " in the order of A / B / C.

[0061] Preferably, the wax remover A / B / C (8 / 9 / 10) is respectively provided with a liquid level meter (81 / 91 / 101) connected to the maximum volume point to the lowest point of the wax remover A / B / C (8 / 9 / 10) body, a first cooling inlet A / B / C (121 / 122 / 123) connected to the liquid phase refrigerant outlet 12, a first cooling outlet A / B / C (161 / 162 / 163) connected to the gas phase refrigerant inlet 16, a wax-containing methanol inlet A / B / C (111 / 112 / 113) connected to the filter 18 outlet, a hot turbine exhaust inlet A / B / C (141 / 142 / 143) connected to the heating turbine exhaust 14, a cold turbine exhaust outlet (151 / 152 / 153) connected to the bypass turbine exhaust 7 with the cold exhaust manifold 15, a clean methanol outlet A / B / C (131 / 132 / 133) connected to the clean methanol tank inlet 13, and a liquefied wax outlet A / B / C (171 / 172 / 173) connected to the subsequent process.

[0062] Preferably, the wax remover A / B / C (8 / 9 / 10) can be divided into three working modes of cooling, low-temperature adsorption, and wax removal during operation, respectively. There is no difference in actual application effect among the wax remover A / B / C (8 / 9 / 10) individuals. The cooling, low-temperature adsorption, and wax removal programs can be set from any one according to actual needs and run in the above sequence in the automatic switching mode.

[0063] Further, the cooling mode of the wax remover A / B / C (8 / 9 / 10) can be manually set to start according to actual needs, or start after the wax removal of a certain one of the corresponding wax remover A / B / C (8 / 9 / 10) ends during the wax removal program. When the corresponding liquefied wax outlet A / B / C (171 / 172 / 173) no longer receives liquefied wax, or when the temperature of the corresponding cold turbine exhaust outlet A / B / C (151 / 152 / 153) is higher than 152℃ and maintains for more than 15 minutes, the corresponding cold turbine exhaust outlet A / B / C (151 / 152 / 153) is automatically controlled to exhaust the turbine exhaust to prevent freezing, the corresponding liquefied wax outlet A / B / C (171 / 172 / 173) outlet valve is automatically controlled to close, the cooling inlet A / B / C (121 / 122 / 123) and the cooling outlet A / B / C (161 / 162 / 163) are automatically controlled to open, and a certain one of the wax remover A / B / C (8 / 9 / 10) enters the cooling mode.

[0064] Further, the start of the low temperature adsorption mode of the wax remover A / B / C (8 / 9 / 10) can be set according to the temperature of one of the cooling outlet A / B / C (161 / 162 / 163). When the temperature is lowered to -28°C, the inlet valve of one of the wax containing methanol inlet A / B / C (111 / 112 / 113) is automatically controlled to open, when the corresponding liquid level meter (81 / 91 / 101) reaches the maximum value, the outlet valve of the corresponding clean methanol outlet A / B / C (131 / 132 / 133) is automatically controlled to open and the flow is automatically controlled to maintain the corresponding liquid level meter (81 / 91 / 101) at the maximum value, and one of the wax remover A / B / C (8 / 9 / 10) enters the low temperature adsorption mode. During the low temperature adsorption, the temperature of the corresponding cooling outlet A / B / C (161 / 162 / 163) is not higher than -22°C.

[0065] Further, the start of the low temperature adsorption mode of the wax remover A / B / C (8 / 9 / 10) can be set according to the temperature of one of the cooling outlet A / B / C (161 / 162 / 163). When the temperature is lowered to -28°C, the inlet valve of one of the wax containing methanol inlet A / B / C (111 / 112 / 113) is automatically controlled to open, when the corresponding liquid level meter (81 / 91 / 101) reaches the maximum value, the outlet valve of the corresponding clean methanol outlet A / B / C (131 / 132 / 133) is automatically controlled to open and the flow is automatically controlled to maintain the corresponding liquid level meter (81 / 91 / 101) at the maximum value, and one of the wax remover A / B / C (8 / 9 / 10) enters the low temperature adsorption mode. During the low temperature adsorption, the temperature of the corresponding cooling outlet A / B / C (161 / 162 / 163) is not higher than -22°C.

[0066] Preferably, the working temperature range of the wax removers A / B / C (8 / 9 / 10) is -35-164℃, and the materials of all pipes, accessories, bodies and the connected parts in the wax removers A / B / C (8 / 9 / 10) should meet the working temperature range.

[0067] Preferably, in the wax removers A / B / C (8 / 9 / 10), the first cooling inlet A / B / C (121 / 122 / 123) and the first cooling outlet A / B / C (161 / 162 / 163) are connected by a first pipe, and the hot turbine exhaust inlet A / B / C (141 / 142 / 143) and the cold turbine exhaust outlet A / B / C (151 / 152 / 153) are connected by a second pipe. The first pipe or the second pipe can be arranged in one or more of the following forms: conjugate, parallel, vertical, parallel, winding, and share one or more of the following: fins, wire mesh, internal filter. For example, the space between the outer wall of the first pipe between the first cooling inlet and the first cooling outlet and the outer wall of the second pipe between the hot turbine exhaust inlet and the cold turbine exhaust outlet is wound, inlaid or arranged in other ways with various forms of fins, wire mesh, internal filter, etc.

[0068] Preferably, the methanol specifications in the wax-containing methanol inlets A / B / C (111 / 112 / 113) of the wax removers A / B / C are as follows: temperature not higher than 50℃, pressure not lower than 0.8MPa, fatty alcohol content not greater than 1000mg / kg, and water content less than or equal to 7%. The flow range of the clean methanol tank inlet 13 is 0-255t / h.

[0069] Preferably, the clean methanol tank inlet 13 should be located as close as possible to the upper part of the methanol tank (if any) or be sent to the methanol tank (if any) by a pump through a buffer tank. The pressure after the clean methanol tank inlet 13 is atmospheric pressure or negative pressure.

[0070] Preferably, heating devices are provided at the bottom of the wax removers A / B / C (8 / 9 / 10), the liquefied wax outlets A / B / C (171 / 172 / 173) and the liquefied wax inlet 17. The heating temperature is greater than 125℃ to ensure smooth flow of liquefied wax. The heating form can be any of electric heating and steam heating.

[0071] Evaporator 19, with evaporating gas inlet and distributor 20, solid wax outlet 21, waste gas outlet 22, wax removal degassing bin 23, and liquefied wax inlet 17 connected to the wax removers A / B / C (8 / 9 / 10) via the liquefied wax outlets A / B / C (171 / 172 / 173). Preferably, the liquefied wax in the liquefied wax inlet 17 and the evaporating medium in the evaporating gas inlet and distributor 20 form a bubbling fluidized bed at the initial stage of contact in the evaporator 19, promoting the separation of the gas and liquid phases in the softened wax, and in the process of continuous evaporation and transportation, the gas, liquid, and solid phases gradually separate, and the wax removal degassing bin 23 helps the solid phase to further separate from the other two phases, which can use one or more of extrusion, scraping, hoisting, and purging. The solid wax outlet 21 can be transported to one or more of a hopper, an open transport vehicle, an automatic packaging or filling system. The waste gas outlet 22 can be transported to a flare line, and the temperature of the waste gas outlet 22 is in the range of 64.8-70°C.

[0072] Preferably, the evaporator 19 can use a negative pressure belt evaporator; the medium in the evaporating gas inlet and distributor 20 can be one or more of nitrogen, carbon dioxide, and stripping gas. Preferably, the angle formed by the connecting line of the start and end points of the evaporator 19 and the horizontal plane is less than 45°.

[0073] To make the purpose, technical scheme and effect of the present application clearer and more explicit, the following refers to the accompanying drawings and further describes the method flow of the present application by examples. Figure 2 The method flow of the present application is further described in detail by examples.

[0074] Taking a methanol-to-olefin device with a scale of 1.8 million tons of methanol processed per year and an operating load of 80-110% as an example (with wax remover A 8 as the first selected setting sequence flow), the method for removing wax from methanol and enriching and recovering in the embodiment of the present application specifically includes the following steps:

[0075] S1. Steam turbine 1 drives compressor 2 (ammonia compressor) to compress ammonia to 0.4-0.8 MPa by 48 t / h of 4.2 MPa medium-pressure steam 4, and after cooling by heat exchanger 3 (or cooler), the flow is controlled to enter wax remover A 8 through first cooling inlet A 121 for expansion and heat absorption, and the fins and wire mesh accessories in contact with the ammonia heat exchange pipe (the pipe between first cooling inlet A / B / C (121 / 122 / 123) and first cooling outlet A / B / C (161 / 162 / 163), located in the internal space of wax remover A / B / C (8 / 9 / 10)) are cooled to -28°C. At this time, wax removers B / C (9 / 10) enter the cooling mode, and turbine exhaust 5 of steam turbine 1 is distributed to enter bypass turbine exhaust 7 by exhaust three-way valve 6;

[0076] S2. After the waxy methanol from the waxy methanol header 11 is filtered by the particle filter 18 to remove 99.5% of the particles with a diameter of 10 μm or more, the waxy methanol enters the wax remover A 8 through the waxy methanol inlet A 111, contacts the low-temperature accessories, and when the liquid level meter A 81 shows a value of 95% or more (at this time, the waxy methanol liquid level is above all the accessories inside the wax remover A 8), the system automatically opens the clean methanol outlet A 131 to send the wax-removed methanol to the clean methanol tank inlet 13, while maintaining the liquid level meter A 81 at a value of 95% or more. At this time, the wax remover A 8 enters the low-temperature adsorption mode;

[0077] S3. When the wax remover A 8 enters the low-temperature adsorption mode, the wax remover B 9 repeats step "S1" to enter the cooling-down mode, and the system automatically controls the "B" part of step "S1" of the wax remover B 9;

[0078] S4. When the methanol inlet and outlet pressure difference table A 83 shows a value higher than 0.06 MPa or the first cooling outlet A 161 shows a temperature lower than -32℃, it indicates that the wax remover A 8 has been saturated with adsorbed wax, at this time, the wax remover B 9 has completed the cooling-down, and the system automatically repeats step "S2" to control the wax remover B 9 to enter the low-temperature adsorption mode, and the system automatically controls the "B" part of step "S1" of the wax remover B 9, while automatically closing the waxy methanol inlet A 111 and keeping the clean methanol outlet A 131 open to the clean methanol tank inlet 13 until the liquid level meter A 81 shows a value of 0%;

[0079] S5. When the wax remover A 8 is exhausted of clean methanol and the wax remover B 9 enters the low-temperature adsorption mode, the wax remover C 10 repeats step "S1" to enter the cooling-down mode, and the system automatically controls the "C" part of step "1" of the wax remover C 10;

[0080] S6. The system automatically opens the hot turbine exhaust inlet A 141 to allow hot exhaust steam at a temperature of 160℃ or more to enter the pipeline inside the wax remover A 8, at this time, the wax remover A 8 enters the warming-up and wax-removal mode, and the wax attached to the accessories in the wax remover A 8 is liquefied due to the high temperature, while the backflushing hot nitrogen gas inlet A 84 is opened to blow the fins, wire mesh, or filter in the wax remover, helping the liquefied wax to enter the subsequent recovery process through the liquefied wax outlet A 171;

[0081] S7. When the wax remover A 8 enters the warming-up and wax-removal mode and the wax remover B 9 completes the low-temperature adsorption mode, the wax remover C 10 repeats step "S2" to enter the low-temperature adsorption mode, and the system automatically controls the "C" part of step "S2" of the wax remover C 10;

[0082] S8. When the temperature of the cold turbine exhaust gas outlet A 151 is higher than 152℃ and maintains for more than 15 minutes, the system automatically closes the hot turbine exhaust gas inlet A 141 and the cold turbine exhaust gas outlet A 151 and blows the turbine exhaust gas pipeline in the wiper by the nitrogen purging device A 82 to prevent low-temperature freezing, the wiper A 8 completes the temperature rising mode and re-enters the temperature lowering mode according to the step "S1". At this time, the wiper A 8 completes a complete cycle of three working modes;

[0083] S9. When the wiper A 8 re-completes the temperature lowering mode, the wiper B 9 executes the wax removal mode, and the wiper C 10 completes the low-temperature adsorption mode, the wiper C 10 is controlled by the sequence controller to repeat the steps "S4" and "S6" to enter the temperature rising mode, and the system automatically controls the operation of the wiper C 10 in the "C" part corresponding to the "A" part in the steps "S4" and "S6". At this time, the wipers A 8 and B 9 respectively follow the previously set sequence cycle working mode;

[0084] S10. During the sequence switching operation of the wipers A / B / C (8 / 9 / 10), the liquefied wax continuously enters the negative pressure belt evaporator 19 from the liquefied wax inlet 17, and the evaporator forms an angle of 15° with the horizontal. The hot nitrogen gas at 65℃ enters the wax removal degassing bin 23 through the micropores on the belt of the negative pressure belt evaporator 19 from the evaporated gas inlet and the distributor 20, evaporates the methanol and low-carbon fatty alcohol in the liquefied wax into gas, and discharges the gas to the flare through the waste gas outlet 22. A small part of the liquid that is not evaporated and not solidified is transported to the sewage plant through the waste liquid discharge outlet 24 by gravity. The liquid wax gradually solidifies, cools and dries during the process of being transported to the end of the evaporator by the belt, and finally forms the product wax which is loaded through the solid wax discharge outlet 21.

[0085] In summary, the embodiment of the present application provides a device and method for compressing refrigerant by steam turbine and lowering the temperature of liquid-phase waxy methanol to make wax precipitate and adhere to the wiper, heating and removing the wax by turbine exhaust gas, and recycling and enriching the wax, which plays a positive role in greatly reducing the impurity content in methanol raw materials, reducing the cleaning frequency and start-stop frequency of various equipment, and preventing production fluctuations. Moreover, the device is simple to operate and can be automatically controlled in sequence.

[0086] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. It is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application are within the scope of the spirit of the present application.

Claims

1. An apparatus for removing wax from methanol and enriching recovery, characterized by: It comprises: a steam turbine, which is connected with an external steam source, has a turbine exhaust steam outlet and an outlet connected with the compressor; a compressor, which is connected with and driven by the outlet of the steam turbine, has a gaseous refrigerant inlet and a compressed medium outlet; a heat exchanger, which is connected with and cooled by the medium outlet of the compressor, has a liquid refrigerant outlet; a filter, which is connected with a total pipe of waxy methanol for filtering particles in the waxy methanol, has an outlet connected with the wax remover; a wax remover, which has a first cooling inlet connected with the liquid refrigerant outlet of the heat exchanger, a waxy methanol inlet connected with the filter outlet, a hot turbine exhaust steam inlet connected with the heated turbine exhaust steam, and has a liquefied wax outlet and a clean methanol outlet; an evaporator, which is connected with the liquefied wax outlet of the wax remover for evaporating and removing residual methanol in the liquefied wax; wherein the turbine exhaust steam outlet of the steam turbine is divided into two branches, the first branch is the heated turbine exhaust steam, and the second branch is the bypass turbine exhaust steam; the wax remover further has a first cooling outlet connected with the gaseous refrigerant inlet of the compressor, and further has a cold turbine exhaust steam outlet connected with the bypass turbine exhaust steam; in the wax remover, the first cooling inlet and the first cooling outlet are connected to form a first pipeline, the hot turbine exhaust steam inlet and the cold turbine exhaust steam outlet are connected to form a second pipeline, and the first pipeline or the second pipeline is arranged in one or more of the following forms: conjugate, parallel, vertical, parallel, and winding; fins, wire mesh or internal filters are arranged between the outer walls of the first pipeline and the second pipeline in the wax remover.

2. The apparatus for removing wax from methanol and enriching recovery according to claim 1, characterized in that: The wax remover is provided with a liquid level meter for measuring the liquid level between the maximum volume point and the lowest point of the body of the wax remover; and the wax remover is provided as one or more.

3. The apparatus for removing wax from methanol and enriching recovery according to claim 2, characterized in that: The evaporator has an evaporation gas inlet and a distributor, a solid wax discharge outlet, a waste gas outlet, a wax discharge degassing bin, and a liquefied wax inlet connected with the liquefied wax outlet of the wax remover.

4. A process for removing wax from methanol and recovering the enriched methanol using the apparatus according to any one of claims 2 to 3, characterized in that: It comprises the following steps: 1) using low-pressure steam to drive the turbine in the steam turbine, driving the compressor to compress the refrigerant, and then cooling the compressed refrigerant in the heat exchanger, and then entering the wax remover to cool the internal accessories, and the wax remover enters the cooling mode; 2) after the waxy methanol passes through the filter to remove particles, it enters the wax remover and contacts the cooled accessories, the dissolved fatty alcohol in the methanol is separated out and adheres to the internal accessories, the wax remover enters the low-temperature adsorption mode, and the clean methanol in the wax remover is discharged; 3) when the wax remover is saturated with adsorbed wax, the heated turbine exhaust steam is introduced into the wax remover, the wax remover enters the warming and wax discharging mode, and the wax adhered to the internal accessories of the wax remover is liquefied due to high temperature, and the liquefied wax containing residual methanol is obtained; 4) the liquefied wax is discharged into the evaporator for treatment, and gaseous and solid wax is obtained; wherein the wax remover is cycled according to steps 1) to 3).

5. The process of claim 4 wherein the methanol is stripped of wax and enriched for recovery. In step 1), the cooling mode of the wax remover is manually set to be turned on, or is turned on after the wax removal of one of the wax removers in the wax remover group is completed during the warming-up wax removal mode; specifically, when the liquefied wax outlet of one wax remover no longer receives liquefied wax, or when the temperature of the cold turbine exhaust outlet is higher than 152℃ and is maintained for more than 15 minutes, the cold turbine exhaust outlet is exhausted of the turbine exhaust antifreeze, the liquefied wax outlet is closed, the first cooling inlet and the first cooling outlet are opened, and the wax remover enters the cooling mode.

6. The process of claim 4 wherein the methanol is stripped of wax and enriched for recovery. In step 2), the start of the low-temperature adsorption mode of the wax remover is set according to the temperature of the first cooling outlet; specifically, when the temperature is reduced to -28℃, the wax-containing methanol inlet is opened, and when the liquid level meter reaches the maximum value, the clean methanol outlet is opened and the flow rate thereof is controlled to maintain the maximum value of the liquid level meter, and the wax remover enters the low-temperature adsorption mode; during the low-temperature adsorption, the temperature of the first cooling outlet is not higher than -22℃.

7. The process of claim 4 wherein the methanol is stripped of wax and enriched for recovery. In step 3), the start of the warming-up wax removal mode of the wax remover is set according to the pressure difference between the wax-containing methanol inlet and the clean methanol outlet, or the temperature of the first cooling outlet; specifically, when the pressure difference is higher than 0.06 MPa, or the temperature of the first cooling outlet is lower than -32℃, it is considered that the low-temperature adsorption wax amount of the wax remover is saturated, all liquid-phase clean methanol in the wax remover is exhausted by closing the wax-containing methanol inlet and keeping the clean methanol outlet open, and the first cooling inlet is closed; when the liquid level of the liquid level meter is 0%, the clean methanol outlet is closed, the first cooling outlet is opened, the hot turbine exhaust inlet and the cold turbine exhaust outlet are opened, and the wax remover enters the warming-up wax removal mode.

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