Energy-saving dimethyl ether vaporization system

Abstract

The utility model discloses an energy-saving dimethyl ether vaporization system, and relates to the technical field of preparation of dimethyl ether by a methanol gas phase dehydration method. Comprising a central control unit, a methanol evaporation unit and a methanol vaporization unit, the controlled end of the central control unit is connected with the methanol evaporation control end and the methanol vaporization control end of the central control unit; the methanol evaporation unit comprises a feeding pump, a feeding regulating valve, a feeding flow meter, a methanol preheater, a methanol evaporation tank, a wastewater heat exchanger and a steam condensate heat exchanger. According to the utility model, impurities in a gas phase of a vaporization system are prevented from being brought into a reaction system to cause hardening of a catalyst bed, increase of system pressure difference, slow heat transfer and temperature collapse of the bed; meanwhile, low-quality methanol can be selected as a raw material, so that the production cost is reduced, the system heat is reasonably utilized, and the steam consumption and the circulating water consumption of cold water and waste water of a post-system are saved.

Description

Technical Field

[0001] The utility model relates to the technical field of preparing dimethyl ether by methanol gas phase dehydration method, in particular to an energy-saving dimethyl ether vaporization system. Background Art

[0002] At present, the production process of dimethyl ether is divided into liquid-phase methanol dehydration method, gas-phase methanol dehydration method and synthesis gas one-step method. Among them, the methanol gas-phase dehydration method is to dehydrate methanol on a modified γ-alumina catalyst to produce dimethyl ether after gasification. The process flow and equipment are relatively simple, with low investment and low operating pressure. Most of the existing industrial devices adopt this process, and its technical characteristics include: (i) when co-producing with the methanol device, the ratio of methanol and dimethyl ether can be adjusted, and the production cost is greatly reduced; (ii) the reactor adopts a multi-stage cold shock fixed bed, with a large catalyst loading capacity, low investment, appropriate reaction temperature, few side reactions, and easy large-scale; (iii) the unique vaporization tower structure and separation process are adopted, and the methanol concentration tower for recovering unreacted methanol is not set up, which not only simplifies the process and reduces investment, but also effectively reduces steam consumption; (iv) the unique tail gas absorption process reduces methanol consumption and energy consumption; (v) the catalyst of this process has been domestically produced and mass-produced, with high activity, good thermal stability and high selectivity, and the selectivity of the dimethyl ether reaction is above 99%.

[0003] The methanol evaporator uses the heat of the wastewater and condensate of the vaporizer tower to evaporate methanol gas after heat exchange in the tube heat exchanger. The methanol gas enters the shell of the gas heat exchanger and the reactor outlet synthesis gas after temperature increase. The methanol evaporator effectively utilizes the heat of the wastewater and condensate of the vaporizer tower to evaporate and vaporize part of the methanol in advance. The unevaporated part of the methanol is then sent to the vaporizer tower for evaporation by the methanol booster pump, which greatly saves the vaporizer tower steam. The methanol evaporator plays a vital role. However, the original design of the system uses refined alcohol as the raw material. In order to reduce production costs, most production units change the raw material to crude alcohol. Since there are more paraffin and other impurities in the crude alcohol, some paraffin and other impurities enter the reactor bed together with the gas phase of the methanol evaporator after the crude alcohol evaporates in the methanol evaporator, resulting in a large pressure difference in the reactor bed and slow heat transfer in the reactor, resulting in poor effect of methanol gas synthesis of dimethyl ether, and in severe cases, the catalyst bed temperature collapses. Utility Model Content

[0004] The utility model aims to remedy the defects of the prior art and provide an energy-saving dimethyl ether vaporization system. The utility model does not agglomerate the dimethyl ether catalyst when using crude alcohol as raw material, reduces the production cost of the dimethyl ether system, and enables the dimethyl ether system to operate economically and stably.

[0005] The utility model is realized by the following technical solutions:

[0006] An energy-saving dimethyl ether vaporization system comprises a central control unit, a methanol evaporation unit and a methanol vaporization unit; the controlled end of the central control unit is connected to the methanol evaporation control end and the methanol vaporization control end of the central control unit; the methanol evaporation unit comprises a feed pump, a feed regulating valve, a feed flow meter, a methanol preheater, a methanol evaporation tank, a wastewater heat exchanger and a steam condensate heat exchanger; the methanol vaporization unit comprises a vaporization tower, a vaporization tower steam reboiler, a vaporization tower steam flow meter, a methanol booster pump, a vaporization tower reflux regulating valve, a vaporization tower reflux flow meter, a vaporization tower steam regulating valve and a vaporization tower liquid level regulating valve; the feed pump is connected to the methanol preheater, and the feed regulating valve and the feed flow meter are respectively installed on the connected pipeline; The shell side outlet of the alcohol preheater is connected with the middle part of the methanol evaporator; the liquid phase of the methanol evaporator is connected with the wastewater heat exchanger and the steam condensate heat exchanger respectively; the liquid phase of the methanol evaporator is connected with the top of the vaporizer, and the pipeline connecting the two is equipped with a methanol booster pump, a vaporizer reflux regulating valve and a vaporizer reflux flowmeter; the top of the methanol evaporator is connected with the 48th tower plate in the middle of the vaporizer; the liquid phase of the vaporizer is connected with the vaporizer steam reboiler; the vaporizer steam flowmeter and the vaporizer steam regulating valve are installed at the shell side inlet of the vaporizer steam reboiler, the vaporizer liquid phase is connected with the shell side inlet of the wastewater heat exchanger, the shell side outlet pipeline of the wastewater heat exchanger is equipped with a vaporizer liquid level regulating valve, and the shell side of the vaporizer steam reboiler is connected with the shell side of the steam condensate heat exchanger.

[0007] A vaporization tower reflux regulating valve is installed on the outlet pipeline of the methanol booster pump, and a vaporization tower reflux flow meter is arranged on the pipelines between the pump and the regulating valve.

[0008] A feed regulating valve is installed on the outlet pipeline of the feed pump, and a feed flow meter is arranged on the pipelines between the pump and the regulating valve.

[0009] A vaporizer tower steam regulating valve is installed on the shell side inlet pipeline of the vaporizer tower steam reboiler, and a vaporizer tower steam flow meter is installed on the pipeline between the two.

[0010] The vaporization tower reflux regulating valve, feed regulating valve and vaporization tower steam regulating valve are all equipped with bypass valves.

[0011] The vaporization tower is a tooth-guided floating valve tower with 80 layers of tower plates in total.

[0012] The liquid phase at the bottom of the methanol evaporator is pressurized by a methanol booster pump and then sent to the 80th tray at the top of the vaporization tower.

[0013] The top gas phase of the methanol evaporator is connected to the tower tray on the 48th floor of the vaporization tower.

[0014] The advantages of the utility model are:

[0015] The utility model changes the 48-layer tower plate from the gas phase pipeline of the methanol evaporator to the middle of the vaporization tower, effectively preventing impurities from directly entering the reactor through the gas phase of the methanol evaporator during the production of dimethyl ether using raw material crude alcohol, causing the catalyst bed to become hardened, thereby realizing the production using raw material crude alcohol, reducing the production cost of dimethyl ether, and making the dimethyl ether system operate economically and stably.

[0016] The utility model prevents impurities in the gas phase of the vaporization system from being brought into the reaction system, causing the catalyst bed to harden, resulting in an increase in the system pressure difference, slow heat transfer, and temperature collapse of the bed; at the same time, low-quality methanol can be selected as a raw material, reducing production costs, rationally utilizing system heat, and saving steam usage and circulating water usage of cold water wastewater in the post-system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0018] Figure 1 The utility model is a schematic structural diagram of an energy-saving dimethyl ether vaporization system.

[0019] In the figure, feed pump 1, feed regulating valve 2, feed flowmeter 3, methanol preheater 4, methanol evaporator 5, wastewater heat exchanger 6, steam condensate heat exchanger 7, vaporization tower 8, vaporization tower steam reboiler 9, vaporization tower steam flowmeter 10, methanol booster pump 11, vaporization tower reflux regulating valve 12, vaporization tower reflux flowmeter 13, vaporization tower steam regulating valve 14, vaporization tower liquid level regulating valve 15, 80th tower tray 80, and 48th tower tray 48. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be clearly and completely described below in combination with the specific embodiments of the utility model and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] The following embodiments are used to illustrate the present invention but are not intended to limit the scope of the present invention. Example 1

[0022] like Figure 1As shown, an energy-saving dimethyl ether vaporization system comprises a central control unit, a methanol evaporation unit and a methanol vaporization unit; the controlled end of the central control unit is connected to the methanol evaporation control end and the methanol vaporization control end of the central control unit; the methanol evaporation unit comprises a feed pump 1, a feed regulating valve 2, a feed flowmeter 3, a methanol preheater 4, a methanol evaporation tank 5, a wastewater heat exchanger 6 and a steam condensate heat exchanger 7; the methanol vaporization unit comprises a vaporization tower 8, a vaporization tower steam reboiler 9, a vaporization tower steam flowmeter 10, a methanol booster pump 11, a vaporization tower reflux regulating valve 12, a vaporization tower reflux flowmeter 13, a vaporization tower steam regulating valve 14 and a vaporization tower liquid level regulating valve 15; the feed pump 1 is connected to the methanol preheater 4, and the feed regulating valve 2 and the feed flowmeter 3 are respectively installed on the connected pipelines; The shell side outlet of the preheater 4 is connected to the middle of the methanol evaporator 5; the liquid phase of the methanol evaporator 5 is respectively connected to the wastewater heat exchanger 6 and the steam condensate heat exchanger 7; the liquid phase of the methanol evaporator 5 is connected to the top of the vaporizer 8, and a methanol booster pump 11, a vaporizer reflux regulating valve 12 and a vaporizer reflux flowmeter 13 are installed on the pipeline connecting the two; the top of the methanol evaporator 5 is connected to the 48th tower tray in the middle of the vaporizer 8; the liquid phase of the vaporizer 8 is connected to the vaporizer steam reboiler 9; the vaporizer steam flowmeter 10 and the vaporizer steam regulating valve 14 are installed at the shell side inlet of the vaporizer steam reboiler 9, the liquid phase of the vaporizer 8 is connected to the shell side inlet of the wastewater heat exchanger 6, the shell side outlet pipeline of the wastewater heat exchanger 6 is installed with a vaporizer liquid level regulating valve 15, and the shell side of the vaporizer steam reboiler 9 is connected to the shell side of the steam condensate heat exchanger 7.

[0023] Figure 1 In the figure, the arrow at the feed pump 1 indicates that the crude alcohol feed comes from the methanol tank area, and the arrow at the top of the vaporizer 8 indicates the reaction system. Example 2

[0024] In the catalyst anti-caking system of the dimethyl ether system of Example 1, a vaporizer reflux regulating valve 12 is installed on the outlet pipe of the methanol booster pump 11, and a vaporizer reflux flowmeter 13 is provided on the pipes of both the pump and the regulating valve.

[0025] A feed regulating valve 2 is installed on the outlet pipeline of the feed pump 1, and a feed flow meter 3 is arranged on the pipelines of both the pump and the regulating valve.

[0026] A vaporizer tower steam regulating valve 14 is installed on the shell side inlet pipeline of the vaporizer tower steam reboiler 9, and a vaporizer tower steam flow meter 10 is installed on the pipeline between the two.

[0027] The vaporization tower reflux regulating valve 12, the feed regulating valve 2 and the vaporization tower steam regulating valve 14 are all equipped with bypass valves.

[0028] The vaporization tower 8 is a tooth-shaped guide float valve tower, and has 80 layers of tower trays in total.

[0029] The liquid phase at the bottom of the methanol evaporator 5 is pressurized by the methanol booster pump 11 and then sent to the 80th tray 80 at the top of the vaporization tower 8.

[0030] The top gas phase of the methanol evaporator 5 is connected to the tray 48 on the 48th floor of the vaporization tower 8 .

[0031] The central control unit adopts a DCS system, and the output ends of the feed flowmeter 3, the vaporization tower steam flowmeter 10 and the vaporization tower reflux flowmeter 13 are connected to the signal input end of the central control unit, and the main valve control end of the central control unit is connected to the controlled ends of the feed regulating valve 2, the vaporization tower reflux regulating valve 12 and the vaporization tower steam regulating valve 14.

[0032] Evaporating part of the methanol into gaseous methanol through the methanol evaporation unit;

[0033] The methanol that has not flashed is sent to the vaporization tower 8 through the methanol booster pump 11 and the vaporization tower reflux regulating valve 12 to control the flow rate;

[0034] The gaseous methanol enters the 48th tray in the middle of the vaporization tower 8 through the gas phase pipeline of the methanol evaporator 5;

[0035] The impurities in the gaseous methanol of the methanol evaporation tank 5 are washed by the reflux liquid at the top of the vaporization tower 8, and the impurities are sent to biochemical treatment along with the waste water at the bottom of the vaporization tower 8.

[0036] The wastewater heat exchanger 6 and the steam condensate heat exchanger 7 arranged at the bottom of the methanol evaporation tank 5 are respectively provided with bypasses to control the temperature of the methanol evaporation tank.

[0037] The feed can be refined alcohol, crude alcohol or lower quality alcohol. The feed is pressurized and sent to the shell side of the methanol preheater 4 for heat exchange through the feed pump 1. The heat source of the tube side is the crude dimethyl ether gas after the methanol gas is reacted. The shell side of the methanol preheater 4 is connected to the methanol evaporator 5. The methanol evaporator 5 is equipped with two reboilers, namely the wastewater heat exchanger 6 and the steam condensate heat exchanger 7. The liquid phase of the methanol evaporator 5 sends the unevaporated methanol to the top of the vaporizer 8 through the methanol booster pump 11 as the vaporizer washing liquid. The gas phase at the top of the methanol evaporator 5 enters the 48th layer of the tower plate in the middle of the vaporizer 8. The impurities entrained in the gas phase can be washed by the washing liquid at the top of the vaporizer. The liquid phase of the vaporizer 8 provides heat through the steam reboiler 9, so that the liquid methanol at the bottom is gasified into vaporized methanol and enters the reaction system. The wastewater at the bottom of the vaporizer 8 enters the methanol evaporator reboiler 9 and provides heat for the methanol evaporator. At the same time, the wastewater temperature is reduced, saving the cooling water evaporation amount for the subsequent process. This utility model can prevent impurities in the vaporization system from being brought into the reaction system, causing the catalyst bed to harden, resulting in increased system pressure difference, slow heat transfer, and bed temperature collapse. At the same time, low-quality methanol can be selected as a raw material to reduce production costs. Reasonable use of system heat can save steam consumption and circulating water consumption of post-system cold water wastewater.

[0038] The raw material crude alcohol is pressurized by the feed pump 1 and controlled by the feed regulating valve 2 to be sent to the shell side of the methanol preheater 4, and then enters the methanol evaporator 5 after heat exchange with the synthesis gas from the reaction system; part of the methanol is evaporated by the wastewater heat exchanger 6 and the steam condensate heat exchanger 7 through the methanol evaporator 5, and enters the 48th layer tray 48 of the vaporizer 8 through the methanol evaporator 5 gas phase; the methanol that has not evaporated in the methanol evaporator 5 is controlled by the vaporizer reflux regulating valve 12 through the methanol booster pump 11, and the vaporizer steam reboiler 9 controls the steam flow through the vaporizer steam regulating valve 14 to provide heat for the vaporizer 8 kettle, and maintain the heat balance of the vaporizer 8. At the same time, the impurities entrained in the vapor phase of the methanol evaporator 5 are washed in the vaporizer 8, and the impurities are sent to the biochemical treatment after the waste water at the bottom of the vaporizer 8 is used for heat utilization, so as to prevent the impurities from entering the subsequent reaction system and causing the reactor bed pressure difference to increase.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. An energy-saving dimethyl ether vaporization system, comprising a central control unit, a methanol evaporation unit and a methanol vaporization unit; characterized in that: The controlled end of the central control unit is connected to the methanol evaporation control end and the methanol vaporization control end of the central control unit; the methanol evaporation unit comprises a feed pump (1), a feed regulating valve (2), a feed flow meter (3), a methanol preheater (4), a methanol evaporation tank (5), a wastewater heat exchanger (6) and a steam condensate heat exchanger (7); the methanol vaporization unit comprises a vaporization tower (8), a vaporization tower steam reboiler (9), a vaporization tower steam flow meter (10), a methanol booster pump (11), a vaporization tower reflux regulating valve (12), a vaporization tower reflux flow meter (13), a vaporization tower steam regulating valve (14) and a vaporization tower liquid level regulating valve (15); the feed pump (1) is connected to the methanol preheater (4), and the feed regulating valve (2) and the feed flow meter (3) are both installed on the pipeline connecting the feed pump (1) and the methanol preheater (4); the shell side outlet of the methanol preheater (4) and the methanol evaporation tank (5) The liquid phase of the methanol evaporator (5) is connected to the wastewater heat exchanger (6) and the steam condensate heat exchanger (7) respectively; the liquid phase of the methanol evaporator (5) is also connected to the top of the vaporizer (8); a methanol booster pump (11), a vaporizer reflux regulating valve (12) and a vaporizer reflux flowmeter (13) are installed on the pipeline connecting the liquid phase of the methanol evaporator (5) and the vaporizer (8); the top of the methanol evaporator (5) is connected to the middle of the vaporizer (8) The liquid phase of the vaporizer (8) is connected to the vaporizer steam reboiler (9); the shell side inlet of the vaporizer steam reboiler (9) is equipped with a vaporizer steam flow meter (10) and a vaporizer steam regulating valve (14); the liquid phase of the vaporizer (8) is connected to the shell side inlet of the wastewater heat exchanger (6); the shell side outlet pipeline of the wastewater heat exchanger (6) is equipped with a vaporizer liquid level regulating valve (15); the shell side of the vaporizer steam reboiler (9) is connected to the shell side of the steam condensate heat exchanger (7).

2. An energy-saving dimethyl ether vaporization system according to claim 1, characterized in that: The vaporization tower reflux regulating valve (12) is installed on the outlet pipe of the methanol booster pump (11), and the vaporization tower reflux flowmeter (13) is arranged on the pipe between the methanol booster pump (11) and the vaporization tower reflux regulating valve (12).

3. The energy-saving dimethyl ether vaporization system according to claim 1, characterized in that: The vaporization tower steam regulating valve (14) is installed on the shell side inlet pipeline of the vaporization tower steam reboiler (9), and the vaporization tower steam flow meter (10) is installed on the pipeline between the vaporization tower steam reboiler (9) and the vaporization tower steam regulating valve (14).

4. The energy-saving dimethyl ether vaporization system according to claim 1, characterized in that: The feed regulating valve (2) is installed on the outlet pipe of the feed pump (1), and the feed flow meter (3) is arranged on the pipe between the feed pump (1) and the feed regulating valve (2).

5. The energy-saving dimethyl ether vaporization system according to claim 1, characterized in that: The vaporization tower reflux regulating valve (12), the feed regulating valve (2) and the vaporization tower steam regulating valve (14) are all equipped with bypass valves.

6. The energy-saving dimethyl ether vaporization system according to claim 1, characterized in that: The vaporization tower (8) is a tooth-shaped guide floating valve tower, with a total of 80 tower trays.

7. An energy-saving dimethyl ether vaporization system according to claim 6, characterized in that: The liquid phase at the bottom of the methanol evaporation tank (5) is pressurized by a methanol booster pump (11) and then sent to the 80th tray at the top of the vaporization tower (8).

8. The energy-saving dimethyl ether vaporization system according to claim 6, characterized in that: The top gas phase of the methanol evaporation tank (5) is connected to the forty-eighth tray of the vaporization tower (8).

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