Energy-saving chloromethane synthesis system

Abstract

The utility model provides an energy-saving chloromethane synthesis system, relates to the technical field of chloromethane synthesis, and solves the technical problem that the existing chloromethane synthesis system adopts a raw material methanol to cool chloromethane and the cooling is incomplete. The device comprises a two-phase heat exchanger communicated with the synthetic reaction kettle, the double-phase heat exchanger is provided with a methanol inlet for introducing methanol, a methanol outlet communicated with an inlet of the synthetic reaction kettle, a chloromethane inlet communicated with an outlet of the synthetic reaction kettle and a chloromethane outlet, and the chloromethane outlet is further communicated with a water washing tower for adding water to wash chloromethane and a water washing tank for cooling the chloromethane again; an inlet of the washing tank is communicated with a water outlet of the washing tower, and an outlet is communicated with an inlet of the synthetic reaction kettle. After absorbing heat of chloromethane, the washing waste liquid and hydrogen chloride are recovered to the synthesis reaction kettle, so that the reaction heat required by the hydrogen chloride reaction is reduced, the system energy consumption is reduced, and the material consumption is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of methyl chloride synthesis, in particular to an energy-saving methyl chloride synthesis system. Background Art

[0002] Methyl chloride, also known as methyl chloride, is a colorless, easily liquefied gas. It is an important chemical raw material, mostly used in the production of methylchlorosilane, tetramethyl lead, methyl cellulose, etc. It can also be used to produce quaternary ammonium compounds, pesticides, etc. It is used as a solvent in the production of isobutyl rubber. The existing methods for producing methyl chloride generally include methane chlorination, methanol chlorination, photochlorination, oxychlorination, etc.; methyl chloride is also produced as a by-product in some industrial processes, such as the production processes of trichlorfon, trichloroacetaldehyde, natural gas chlorination to produce carbon tetrachloride and phosphamidon. With the gradual promotion of organosilicon deep processing equipment, methyl chloride, as one of the key raw materials for the synthesis of organosilicon monomers, its production cost directly affects the market revenue of subsequent products.

[0003] Among them, the methanol chlorination method is currently a widely used method for producing methyl chloride. This method is to heat methanol with steam to vaporize it and then pass it into a reactor to react with hydrogen chloride under the condition of zinc chloride as a catalyst to produce methyl chloride. In this production process, the material needs to be heated before the reaction and cooled after the reaction, and the heat released in the reaction is not recycled.

[0004] Therefore, the patent with publication number CN107490315A proposes an energy-saving graphite heat exchanger and production method that utilizes the heat energy of methyl chloride synthesis, which uses the hot reaction product to heat and vaporize methanol; instead of using circulating cooling water to cool the reaction product, the raw material liquid methanol is used to cool the reactant. Through such a process route arrangement, the use of other heat sources such as steam or heat transfer oil to heat and vaporize methanol is reduced, and the use of circulating cooling water is also reduced.

[0005] This method effectively utilizes the heat of the reactants and reduces the use of cooling water. However, the reaction products that produce methyl chloride and methanol are only heat exchanged. The heat recovery will be related to the heat exchange efficiency of the heat exchanger and the length of the heat exchange process. The constant pressure specific heat capacity of methanol at 20°C is 2.51 [kJ / (kg*K)], which is less than half of the specific heat capacity of water at the same pressure. After the heat exchange, the reaction products often still have a lot of heat that is not recovered, and some cooling water is appropriately required for re-cooling. In actual production, the corresponding cooling step is not omitted, but a new process step is added. Utility Model Content

[0006] The utility model aims to provide an energy-saving chloromethane synthesis system to solve the technical problem that the existing chloromethane synthesis system uses raw material methanol to cool the chloromethane, but the cooling is incomplete.

[0007] The embodiments of the present invention are implemented by the following technical solutions:

[0008] An energy-saving methyl chloride synthesis system comprises a methanol vaporizer connected to methanol and a synthesis reactor whose inlet is connected to the outlet of the methanol vaporizer, and also comprises a two-phase heat exchanger connected to the synthesis reactor; the two-phase heat exchanger is provided with a methanol inlet for connecting to methanol, a methanol outlet connected to the inlet of the synthesis reactor, a methyl chloride inlet and a methyl chloride outlet connected to the outlet of the synthesis reactor, the methyl chloride outlet is also connected to a water washing tower for washing the methyl chloride with water and a water washing tank for cooling the methyl chloride again; the water washing tank inlet is connected to the water washing tower drain outlet, and the outlet is connected to the inlet of the synthesis reactor.

[0009] Preferably, the water washing tank comprises a vent disposed at the lower portion for introducing methyl chloride and an exhaust port disposed at the upper portion for exhausting methyl chloride.

[0010] Preferably, the vent of the washing tank is provided with a one-way valve for blocking the washing waste liquid.

[0011] Preferably, the water washing tank further comprises a water inlet arranged at the top for introducing the water washing waste liquid of the water washing tower and a drain outlet for discharging the water washing waste liquid after heat exchange, and the drain outlet of the water washing tank is connected to the inlet of the synthesis reactor.

[0012] Preferably, the drain outlet of the water washing tank is provided with a drain pipe for communicating with the inlet of the synthesis reactor, and the drain pipe is also connected with a pipeline for introducing hydrogen chloride.

[0013] Preferably, it also includes a first three-way valve connecting the two-phase heat exchanger to the water washing tank and the water washing tower.

[0014] Preferably, it also includes a second three-way valve that connects methanol to the methanol vaporizer and the two-phase heat exchanger.

[0015] Preferably, it also includes an alkali washing tower and a sulfuric acid drying tower which are sequentially connected to the material outlet of the water washing tower.

[0016] By adopting the technical scheme, after the raw material methanol absorbs the heat of methyl chloride, the methyl chloride can be introduced into the water washing tank to further exchange heat with the water washing waste liquid generated in the water washing tower. Compared with the methanol raw material, the water washing waste liquid has a higher specific heat capacity, a lower temperature, and a greater heat absorption. The water washing waste liquid is mainly produced by washing the impurity gases methanol and hydrogen chloride in the methyl chloride in the water washing tower, and is recovered to the synthesis reactor together with the hydrogen chloride after absorbing heat, which can also reduce the reaction heat required for the hydrogen chloride reaction, further recover the heat generated by the reaction, and reduce the energy consumption of the system.

[0017] The technical solution of the embodiment of the utility model has at least the following advantages and beneficial effects:

[0018] 1. The utility model recovers the water-washing waste liquid to the synthesis reactor together with hydrogen chloride after absorbing the heat of methyl chloride, thereby reducing the reaction heat required for the hydrogen chloride reaction and reducing the energy consumption of the system;

[0019] 2. The utility model realizes the full recovery of the raw materials washed out of the water washing tower on the basis of realizing the full recovery of the reaction heat, thereby reducing energy consumption and material consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the structure of an energy-saving chloroform synthesis system provided in Example 1 of the utility model;

[0022] Icons: 1. Methanol vaporizer; 2. Synthesis reactor; 3. Dual-phase heat exchanger; 4. Water washing tank; 5. Water washing tower; 6. Alkali washing tower; 7. Sulfuric acid drying tower; 8. 、 First three-way valve; 9. Second three-way valve. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0026] In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does 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 cannot be understood as a limitation on the present invention.

[0027] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Example 1

[0029] A energy-saving methyl chloride synthesis system comprises a methanol vaporizer 1 connected to methanol and a synthesis reactor 2 whose inlet is connected to the outlet of the methanol vaporizer 1, and a two-phase heat exchanger 3 connected to the synthesis reactor 2; the two-phase heat exchanger 3 is provided with a methanol inlet for connecting to methanol, a methanol outlet connected to the inlet of the synthesis reactor 2, a methyl chloride inlet and a methyl chloride outlet connected to the outlet of the synthesis reactor 2, the methyl chloride outlet is also connected to a water washing tower 5 for washing the methyl chloride with water and a water washing tank 4 for cooling the methyl chloride again; the inlet of the water washing tank 4 is connected to the drainage outlet of the water washing tower 5, and the outlet is connected to the inlet of the synthesis reactor 2.

[0030] In this embodiment, the water washing tank 4 includes a vent disposed at the lower portion for introducing methyl chloride and an exhaust port disposed at the upper portion for exhausting methyl chloride.

[0031] In this embodiment, the vent of the washing tank 4 is provided with a one-way valve for blocking the waste washing liquid.

[0032] In this embodiment, the water washing tank 4 also includes a water inlet arranged at the top for introducing the water washing waste liquid of the water washing tower 5 and a drain outlet for discharging the water washing waste liquid after heat exchange, and the drain outlet of the water washing tank 4 is connected to the inlet of the synthesis reactor 2.

[0033] In this embodiment, the drain outlet of the water washing tank 4 is provided with a drain pipe for communicating with the inlet of the synthesis reactor 2, and the drain pipe is also connected with a pipeline for introducing hydrogen chloride.

[0034] In this embodiment, a first three-way valve 8 is further included to connect the two-phase heat exchanger 3 to the water washing tank 4 and the water washing tower 5 .

[0035] In this embodiment, a second three-way valve 9 is further included to connect the methanol vaporizer 1 and the two-phase heat exchanger 3 with methanol.

[0036] In this embodiment, it also includes an alkali washing tower 6 and a sulfuric acid drying tower 7 which are sequentially connected to the material outlet of the water washing tower 5.

[0037] Working principle and usage process:

[0038] By adopting the technical scheme, after the raw material methanol absorbs the heat of methyl chloride, the methyl chloride can be introduced into the water washing tank 4, and further heat is exchanged with the water washing waste liquid generated in the water washing tower 5. Compared with the methanol raw material, the water washing waste liquid has a higher specific heat capacity, a lower temperature, and a larger heat absorption. The water washing waste liquid is mainly produced by washing the impurity gases methanol and hydrogen chloride in the methyl chloride in the water washing tower 5, and is recovered to the synthesis reactor 2 together with the hydrogen chloride after absorbing heat.

[0039] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An energy-saving methyl chloride synthesis system, comprising a methanol vaporizer (1) connected to methanol and a synthesis reactor (2) whose inlet is connected to the outlet of the methanol vaporizer (1), characterized in that: It also includes a two-phase heat exchanger (3) connected to the synthesis reactor (2); the two-phase heat exchanger (3) is provided with a methanol inlet for receiving methanol, a methanol outlet connected to the inlet of the synthesis reactor (2), a chloromethane inlet and a chloromethane outlet connected to the outlet of the synthesis reactor (2), the chloromethane outlet is also connected to a water washing tower (5) for washing the chloromethane with water and a water washing tank (4) for cooling the chloromethane again; the inlet of the water washing tank (4) is connected to the drain outlet of the water washing tower (5), and the outlet is connected to the inlet of the synthesis reactor (2).

2. An energy-saving methyl chloride synthesis system according to claim 1, characterized in that: The water washing tank (4) comprises a vent provided at the lower part for introducing methyl chloride and an exhaust port provided at the upper part for exhausting methyl chloride.

3. An energy-saving methyl chloride synthesis system according to claim 2, characterized in that: The vent of the washing tank (4) is provided with a one-way valve for blocking the waste washing liquid.

4. An energy-saving methyl chloride synthesis system according to any one of claims 1 to 3, characterized in that: The water washing tank (4) also includes a water inlet arranged at the top for introducing the water washing waste liquid from the water washing tower (5) and a drain outlet for discharging the water washing waste liquid after heat exchange, and the drain outlet of the water washing tank (4) is connected to the inlet of the synthesis reactor (2).

5. An energy-saving methyl chloride synthesis system according to claim 4, characterized in that: The water outlet of the water washing tank (4) is provided with a drainage pipe for communicating with the inlet of the synthesis reaction kettle (2), and the drainage pipe is also connected with a pipeline for introducing hydrogen chloride.

6. An energy-saving methyl chloride synthesis system according to any one of claims 1 to 3 and 5, characterized in that: It also includes a first three-way valve (8) that connects the two-phase heat exchanger (3) to the water washing tank (4) and the water washing tower (5).

7. An energy-saving methyl chloride synthesis system according to any one of claims 1 to 3 and 5, characterized in that: It also includes a second three-way valve (9) for connecting methanol to the methanol vaporizer (1) and the two-phase heat exchanger (3).

8. An energy-saving methyl chloride synthesis system according to any one of claims 1 to 3 and 5, characterized in that: It also includes an alkali washing tower (6) and a sulfuric acid drying tower (7) which are sequentially connected to the material outlet of the water washing tower (5).

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