System with high conversion per pass for preparing dimethyl ether from methanol

Abstract

The utility model discloses a system for preparing dimethyl ether from methanol with high conversion per pass, and belongs to the technical field of dimethyl ether preparation. The system comprises a methanol storage tank, a methanol gasification tower, a heat exchanger, a DME rectification system, a first-stage reactor, a second-stage reactor and the like, one part of reaction heat generated in the second-stage reactor is exchanged to a methanol raw material before methanol gasification, and the other part of reaction heat is exchanged to gasified methanol for first-stage reaction. The system makes full use of reaction heat, reduces external heat supply, is low in energy consumption, can improve the conversion per pass of dimethyl ether synthesis reaction, reduces invalid circulation of unreacted methanol, and reduces invalid energy consumption. According to the system, the single-pass conversion rate of methanol is high, so that the steam consumption of the rectification device can be greatly reduced; the method has the remarkable effects of high efficiency, energy conservation and consumption reduction.

Description

Technical Field

[0001] The utility model relates to a system for preparing dimethyl ether from methanol with a high single-pass conversion rate, relates to the field of chemical production, and specifically belongs to the technical field of dimethyl ether preparation. Background Art

[0002] Dimethyl ether (DME) has good solubility and volatility, making it a suitable propellant for use in aerosol and spray products. Compared to traditional propellants such as Freon, DME is non-ozone depleting and relatively inexpensive. For example, in products such as air fresheners, hair sprays, and insecticides, DME effectively and evenly disperses and sprays the active ingredients, providing excellent product performance. Furthermore, DME is a clean fuel alternative. Its high cetane number allows for excellent combustion in compression-ignition engines, generating relatively low levels of pollutants such as particulate matter and nitrogen oxides. Industrially, DME can be used as a substitute for liquefied petroleum gas (LPG) in both domestic and industrial applications. DME can also be blended with diesel to improve its combustion properties and reduce exhaust emissions. As a clean energy source and an important chemical raw material, market demand for DME is rapidly growing.

[0003] Methanol dehydration is one of the main methods currently used industrially to produce dimethyl ether. It involves the intermolecular dehydration of methanol in the presence of a catalyst to produce dimethyl ether. While this method offers low investment, flexible product adjustments, and a simple process, it also suffers from insufficient utilization of waste heat and high energy consumption. The main reactions are as follows.

[0004] 2CH3OH=CH3OCH3 +H2O -23.14kJ / mol

[0005] The reaction is exothermic, with a heat of -23.14 kJ / mol per mol of dimethyl ether produced. This heat of reaction affects the reaction temperature and, consequently, the reaction progress. Removing and further utilizing this heat during the synthesis process is a challenge that needs to be addressed in this process. Utility Model Content

[0006] In order to solve the problems existing in the prior art, the utility model provides a system for producing dimethyl ether from methanol with a high single-pass conversion rate. Since the production of dimethyl ether from methanol is an exothermic reaction, removing the reaction heat and optimizing the reaction temperature can achieve a higher methanol conversion rate, lower energy consumption, higher thermal energy utilization, low production costs, and good system stability.

[0007] To achieve the above purpose, the technical solution of the utility model is as follows:

[0008] A methanol-to-dimethyl ether high-per-pass conversion system, wherein a methanol storage tank is connected to a preheater via a methanol delivery pump, the outlet of the preheater is connected to the inlet of a methanol vaporization tower, the outlet of the methanol vaporization tower is connected to the tubular layer inlet of a secondary reactor, and the tubular layer outlet of the secondary reactor is connected to the inlet of a primary reactor;

[0009] The preheater adopts one-stage preheating or two-stage preheating; when one-stage preheating is adopted, the outlet of the first reactor is directly connected to the reaction inlet of the second reactor; when two-stage preheating is adopted, the outlet of the first reactor is connected to the reaction inlet of the second reactor after passing through the preheater; the reaction outlet of the second reactor is connected to the inlet of the DME distillation system after passing through the preheater, and the raw material outlet of the DME distillation system is returned to the methanol storage tank through the methanol recovery pipe via the recovered methanol delivery pump.

[0010] When the preheater adopts two-stage preheating, the preheater includes a first-stage preheater and a second-stage preheater;

[0011] The methanol storage tank is connected to the shell of the first-stage preheater and the shell of the second-stage preheater in sequence after passing through the methanol delivery pump, and the shell outlet of the second-stage preheater is connected to the inlet of the methanol vaporization tower;

[0012] The outlet of the primary reactor is connected to the tube layer inlet of the secondary preheater, and the tube layer outlet of the secondary preheater is connected to the reaction inlet of the secondary reactor;

[0013] The reaction outlet of the secondary reactor is connected to the tube layer inlet of the primary preheater, and the tube layer outlet of the primary preheater is connected to the inlet of the DME distillation system.

[0014] Furthermore, in a system for producing dimethyl ether from methanol with a high single-pass conversion rate, when the preheater adopts a two-stage preheating method, the preheater includes a primary preheater and a secondary preheater;

[0015] The methanol storage tank is connected to the shell layer of the first preheater and the shell layer of the second preheater in sequence after passing through the methanol delivery pump. The shell layer outlet of the second preheater is connected to the inlet of the methanol vaporization tower. The outlet of the methanol vaporization tower is connected to the tube layer inlet of the second reactor. The tube layer outlet of the second reactor is connected to the inlet of the first reactor.

[0016] The outlet of the primary reactor is connected to the pipe layer inlet of the secondary preheater, and the pipe layer outlet of the secondary preheater is connected to the reaction inlet of the secondary reactor; the reaction outlet of the secondary reactor is connected to the pipe layer inlet of the primary preheater, and the pipe layer outlet of the primary preheater is connected to the inlet of the distillation system; the raw material outlet of the DME distillation system is returned to the methanol storage tank through the methanol recovery pipe via the recovered methanol delivery pump.

[0017] When the preheater adopts one-stage preheating, the preheater is a one-stage preheater;

[0018] The methanol storage tank is connected to the shell inlet of the primary preheater after passing through the methanol delivery pump. One branch of the shell outlet of the primary preheater is connected to the inlet of the methanol vaporizer. The other branch is connected to the primary reactor and then to the inlet of the steam drum. The outlet of the steam drum is connected to the pipeline from the outlet of the methanol vaporizer to the tube inlet of the secondary reactor.

[0019] The reaction outlet of the secondary reactor passes through the tube layer inlet of the primary preheater, and the tube layer outlet of the primary preheater is connected to the inlet of the DME distillation system.

[0020] Furthermore, in a system for producing dimethyl ether from methanol with a high single-pass conversion rate, when the preheater adopts a first-stage preheating, the preheater is a first-stage preheater.

[0021] The methanol storage tank is connected to the shell inlet of the primary preheater after passing through the methanol delivery pump. A branch of the shell outlet of the primary preheater is connected to the inlet of the methanol vaporizer, and the outlet of the methanol vaporizer is connected to the tube layer heat exchange inlet of the secondary reactor; another branch is connected to the primary reactor and then to the inlet of the steam drum; the outlet of the steam drum is connected to the pipeline from the outlet of the methanol vaporizer to the tube layer inlet of the secondary reactor, and finally connected to the tube layer heat exchange inlet of the secondary reactor;

[0022] The tube layer heat exchange outlet of the secondary reactor is connected to the inlet of the primary reactor; the outlet of the primary reactor is directly connected to the reaction inlet of the secondary reactor; the reaction outlet of the secondary reactor is connected to the tube layer inlet of the primary preheater, the tube layer outlet of the primary preheater is connected to the inlet of the DME distillation system, and the raw material outlet of the DME distillation system is returned to the methanol storage tank through the methanol recovery pipe via the recovered methanol delivery pump.

[0023] Furthermore, the DME distillation system is provided with a non-condensable gas outlet and a product outlet.

[0024] Furthermore, the water outlet of the methanol gasification tower and the water outlet of the DME distillation system are connected to a sewage treatment system.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention proposes a novel two-stage reaction system for producing dimethyl ether from methanol, which can fully utilize the reaction heat of the entire dimethyl ether production system, reduce external heat supply, and reduce energy consumption, while also improving the single-pass conversion rate of the dimethyl ether synthesis reaction, reducing the ineffective circulation of unreacted methanol, and reducing ineffective energy consumption.

[0027] Due to the high per-pass conversion rate of methanol, the present invention also significantly reduces the steam consumption of the distillation unit. The present invention solves the problems of low per-pass conversion rate, ineffective circulation of unreacted methanol, low thermal efficiency of the entire system, and insufficient waste heat utilization in the existing two-step production process of methanol dehydration to dimethyl ether. The per-pass conversion rate is increased from 80-85% in the traditional process to 90-95%, significantly improving efficiency. The entire dimethyl ether production system fully utilizes the reaction heat and consumes less energy, achieving significant effects of high efficiency, energy saving, and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the system for producing dimethyl ether with high single-pass conversion rate from methanol in Example 1.

[0029] Figure 2 Schematic diagram of the system for producing dimethyl ether with high single-pass conversion rate from methanol in Example 2.

[0030] In the figure: V-101, methanol storage tank, V-102, steam drum, F-101, methanol vaporization tower, E-101, primary preheater, E-102, secondary preheater, R-102, secondary reactor, R-101, primary reactor, P-101A / B, methanol delivery pump, P-102A / B, recovered methanol delivery pump, T-101, DME distillation system. DETAILED DESCRIPTION

[0031] The following will be combined with specific embodiments and examples to specifically explain the present invention, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific embodiments and examples are used to illustrate the present invention, rather than to limit the present invention.

[0032] Throughout this specification, unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, 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 utility model belongs. In the event of any conflict, the present specification shall take precedence.

[0033] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0034] The invention is achieved through the following technical solution: a system for producing dimethyl ether from methanol with a high single-pass conversion rate, wherein a methanol storage tank V-101 is connected to a preheater after passing through a methanol delivery pump P-101A / B, the outlet of the preheater is connected to the inlet of a methanol vaporization tower F-101, the outlet of the methanol vaporization tower F-101 is connected to the pipe layer inlet of a secondary reactor R-102, and the pipe layer outlet of the secondary reactor R-102 is connected to the inlet of a primary reactor R-101;

[0035] The preheater adopts one-stage preheating or two-stage preheating; when using one-stage preheating, the outlet of the first reactor R-101 is directly connected to the reaction inlet of the second reactor R-102; when using two-stage preheating, the outlet of the first reactor R-101 is connected to the reaction inlet of the second reactor R-102 after passing through the preheater; the reaction outlet of the second reactor R-102 is connected to the inlet of the DME distillation system T-101 after passing through the preheater, and the raw material outlet of the DME distillation system T-101 is returned to the methanol storage tank V-101 through the methanol recovery pipe via the recovered methanol delivery pump P-102A / B.

[0036] When the preheater adopts two-stage preheating, the preheater includes a first-stage preheater E-101 and a second-stage preheater E-102;

[0037] The methanol storage tank V-101 is connected to the shell of the first-stage preheater E-101 and the shell of the second-stage preheater E-102 through the methanol delivery pump P-101A / B in sequence. The shell outlet of the second-stage preheater E-102 is connected to the inlet of the methanol vaporization tower F-101.

[0038] The outlet of the primary reactor R-101 is connected to the tube layer inlet of the secondary preheater E-102, and the tube layer outlet of the secondary preheater E-102 is connected to the reaction inlet of the secondary reactor R-102;

[0039] The reaction outlet of the secondary reactor R-102 is connected to the tube layer inlet of the primary preheater E-101, and the tube layer outlet of the primary preheater E-101 is connected to the inlet of the DME distillation system T-101.

[0040] When the preheater adopts the first-stage preheating, the preheater is the first-stage preheater E-101;

[0041] The methanol storage tank V-101 is connected to the shell inlet of the primary preheater E-101 through the methanol delivery pump P-101A / B. One branch of the shell outlet of the primary preheater E-101 is connected to the inlet of the methanol vaporizer F-101. The other branch is connected to the primary reactor R-101 and then to the inlet of the steam drum V-102. The outlet of the steam drum V102 is connected to the pipeline from the outlet of the methanol vaporizer F-101 to the tube inlet of the secondary reactor R-102.

[0042] The reaction outlet of the secondary reactor R-102 passes through the tube layer inlet of the primary preheater E-101, and the tube layer outlet of the primary preheater E-101 is connected to the inlet of the DME distillation system T-101.

[0043] The DME distillation system T-101 is equipped with a non-condensable gas outlet and a product outlet.

[0044] The water outlet of the methanol vaporization tower F-101 and the water outlet of the DME distillation system T-101 are connected to the sewage treatment system.

[0045] Example 1

[0046] Figure 1 A system for producing dimethyl ether from methanol with a high single-pass conversion rate is shown in FIG. When the preheater adopts a two-stage preheating method, the preheater includes a primary preheater E-101 and a secondary preheater E-102.

[0047] The methanol storage tank V-101 is connected to the shells of the primary preheater E-101 and the secondary preheater E-102 in sequence through the methanol delivery pump P-101A / B. The shell outlet of the secondary preheater E-102 is connected to the inlet of the methanol vaporization tower F-101. The outlet of the methanol vaporization tower F-101 is connected to the heat exchange inlet of the tube layer of the secondary reactor R-102. The heat exchange outlet of the tube layer of the secondary reactor R-102 is connected to the inlet of the primary reactor R-101.

[0048] The outlet of the primary reactor R-101 is connected to the pipe layer inlet of the secondary preheater E-102, and the pipe layer outlet of the secondary preheater E-102 is connected to the reaction inlet of the secondary reactor R-102; the reaction outlet of the secondary reactor R-102 is connected to the pipe layer inlet of the primary preheater E-101, and the pipe layer outlet of the primary preheater E-101 is connected to the inlet of the DME distillation system T-101; the raw material outlet of the DME distillation system T-101 is returned to the methanol storage tank V-101 through the methanol recovery pipe via the recovered methanol delivery pump P-102A / B.

[0049] When the above technical solution is adopted, the process flow includes:

[0050] ① The methanol from the tank area is mixed with the recovered methanol delivered by the recovery methanol delivery pump P-102A / B from the distillation system and then enters the methanol storage tank V-101. After passing through the methanol delivery pump P-101A / B, the shell of the first-stage preheater E-101 and the shell of the second-stage preheater E-102 for heat exchange, it enters the methanol vaporization tower F-101.

[0051] ② The gaseous methanol coming out of the methanol vaporization tower F-101 enters the secondary reactor R-102 (air-cooled reactor) tube layer heat exchange and then enters the primary reactor R-101 (adiabatic reactor) catalyst bed for reaction. The reaction gas passes through the secondary preheater E-102 tube layer heat exchange and then enters the secondary reactor R-102 (air-cooled reactor) tube layer catalyst bed for reaction. The reaction gas coming out of the air-cooled reactor R-2002 passes through the primary preheater E-101 tube layer heat exchange and then enters the DME distillation system T-101.

[0052] ③ After passing through the DME distillation system T-101, the recovered methanol is returned to the methanol storage tank V-101, the non-condensable gas goes to the flare, and the finished dimethyl ether is sent to the tank area.

[0053] Example 2

[0054] Figure 2 A system for producing dimethyl ether from methanol with high single-pass conversion rate is shown. When the preheater adopts a single-stage preheating method, the preheater is a single-stage preheater E-101.

[0055] Methanol storage tank V-101 is connected to the shell inlet of primary preheater E-101 through methanol delivery pump P-101A / B. One branch of the shell outlet of primary preheater E-101 is connected to the inlet of methanol vaporizer F-101. The outlet of methanol vaporizer F-101 is connected to the tube inlet of secondary reactor R-102. Another branch is connected to primary reactor R-101 and then to the inlet of steam drum V-102. The outlet of steam drum V102 is connected to the pipeline from the outlet of methanol vaporizer F-101 to the tube inlet of secondary reactor R-102.

[0056] The tube layer outlet of the secondary reactor R-102 is connected to the inlet of the primary reactor R-101;

[0057] The outlet of the primary reactor R-101 is directly connected to the reaction inlet of the secondary reactor R-102; the reaction outlet of the secondary reactor R-102 passes through the pipe layer inlet of the primary preheater E-101, and the pipe layer outlet of the primary preheater E-101 is connected to the inlet of the DME distillation system T-101. The raw material outlet of the DME distillation system T-101 is returned to the methanol storage tank V-101 through the methanol recovery pipe via the recovered methanol delivery pump P-102A / B.

[0058] When the above technical solution is adopted, the process flow includes:

[0059] ① The methanol from the tank area is mixed with the recovered methanol delivered by the recovery methanol delivery pump P-102A / B from the distillation system and then enters the methanol storage tank V-101. After passing through the methanol delivery pump P-101A / B and the preheater E-101 (shell layer), it is divided into two paths. One path directly enters the methanol vaporization tower F-101, and the other path enters the steam drum V-102 of the primary reactor R-101 (heat transfer reactor).

[0060] ②The methanol entering the drum V-102 acts as a heat transfer medium to carry away the reaction heat of the primary reactor R-101. The gaseous methanol produced by the drum V-102 is mixed with the gaseous methanol from the methanol vaporization tower F-101 and then enters the secondary reactor R-102 (air-cooled reactor) tube for heat exchange. After that, it enters the catalyst bed in the tube of the primary reactor R-101 (heat transfer reactor) for reaction. The reaction gas enters the catalyst bed between the tubes of the secondary reactor R-102 (air-cooled reactor) for reaction.

[0061] ③ The reaction gas from the secondary reactor R-102 (air-cooled reactor) enters the DME distillation system T-101 after heat exchange in the preheater E-101 (tube layer).

[0062] ④ After passing through the DME distillation system T-101, the recovered methanol is returned to the methanol storage tank V-101, the non-condensable gas goes to the flare, and the finished dimethyl ether is sent to the tank area.

[0063] Compared with the existing technology, the present invention can reasonably give full play to the advantages of the two-stage reaction, on the one hand, improving the methanol single-pass conversion rate, and on the other hand, making full use of the heat generated in the entire production system, with a more optimized route and suitable for large-scale industrialization.

[0064] The above description is merely an embodiment of the present application and does not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, it is not intended to limit the present application. Any technical personnel familiar with this profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A system for producing dimethyl ether from methanol with high single-pass conversion rate, characterized by: The methanol storage tank (V-101) is connected to the preheater after passing through the methanol delivery pump (P-101A / B), the outlet of the preheater is connected to the inlet of the methanol vaporization tower (F-101), the outlet of the methanol vaporization tower (F-101) is connected to the pipe layer inlet of the secondary reactor (R-102), and the pipe layer outlet of the secondary reactor (R-102) is connected to the inlet of the primary reactor (R-101); The preheater adopts one-stage preheating or two-stage preheating; when the one-stage preheating is adopted, the outlet of the first reactor (R-101) is directly connected to the reaction inlet of the second reactor (R-102); when the two-stage preheating is adopted, the outlet of the first reactor (R-101) is connected to the reaction inlet of the second reactor (R-102) after passing through the preheater; The reaction outlet of the secondary reactor (R-102) is connected to the inlet of the DME distillation system (T-101) after passing through the preheater. The raw material outlet of the DME distillation system (T-101) is returned to the methanol storage tank (V-101) through the methanol recovery pipe via the recovered methanol delivery pump (P-102A / B).

2. The system for producing dimethyl ether from methanol with high single-pass conversion according to claim 1, characterized in that: When the preheater adopts two-stage preheating, the preheater includes a first-stage preheater (E-101) and a second-stage preheater (E-102); The methanol storage tank (V-101) is connected to the shell of the first-stage preheater (E-101) and the shell of the second-stage preheater (E-102) in sequence after passing through the methanol delivery pump (P-101A / B). The shell outlet of the second-stage preheater (E-102) is connected to the inlet of the methanol vaporization tower (F-101); The outlet of the primary reactor (R-101) is connected to the tube layer inlet of the secondary preheater (E-102), and the tube layer outlet of the secondary preheater (E-102) is connected to the reaction inlet of the secondary reactor (R-102); The reaction outlet of the secondary reactor (R-102) is connected to the tube layer inlet of the primary preheater (E-101), and the tube layer outlet of the primary preheater (E-101) is connected to the inlet of the DME distillation system (T-101).

3. The system for producing dimethyl ether from methanol with high single-pass conversion according to claim 1, characterized in that: When the preheater adopts one-stage preheating, the preheater is a one-stage preheater (E-101); The methanol storage tank (V-101) is connected to the shell inlet of the primary preheater (E-101) through the methanol delivery pump (P-101A / B). One branch of the shell outlet of the primary preheater (E-101) is connected to the inlet of the methanol vaporizer (F-101). The other branch is connected to the primary reactor (R-101) and then to the inlet of the steam drum (V-102). The outlet of the steam drum (V-102) is connected to the pipeline from the outlet of the methanol vaporizer (F-101) to the tube inlet of the secondary reactor (R-102). The reaction outlet of the secondary reactor (R-102) passes through the tube layer inlet of the primary preheater (E-101), and the tube layer outlet of the primary preheater (E-101) is connected to the inlet of the DME distillation system (T-101).

4. The system for producing dimethyl ether from methanol with high single-pass conversion according to claim 1, characterized in that: The DME distillation system (T-101) is provided with a non-condensable gas outlet and a product outlet.

5. The system for producing dimethyl ether from methanol with high single-pass conversion according to claim 1, characterized in that: The water outlet of the methanol vaporization tower (F-101) and the water outlet of the DME distillation system (T-101) are connected to the sewage treatment system.

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