CN108101748B

CN108101748B - Four-tower three-effect methanol rectification energy-saving process method and device

Info

Publication number: CN108101748B
Application number: CN201810101973.2A
Authority: CN
Inventors: 蓝仁水; 黄贵明
Original assignee: New Tianjin T & D Co ltd
Current assignee: New Tianjin T & D Co ltd
Priority date: 2018-02-01
Filing date: 2018-02-01
Publication date: 2024-05-07
Anticipated expiration: 2038-02-01
Also published as: CN108101748A

Abstract

The invention relates to a four-tower three-effect methanol rectifying energy-saving process method and a device, which are used for producing methanol from crude methanol through a rectifying process. The whole device at least comprises four towers of a light component removing tower (T201), a first rectifying tower (T202), a second rectifying tower (T203), a third rectifying tower (T204) and the like and matched equipment thereof. The invention adopts a multi-tower multi-effect heat integration process method, can overcome the defects of the prior art, reduces the operation energy consumption by more than 30 percent, has obvious practicality and economic benefit, and has wide application prospect.

Description

Four-tower three-effect methanol rectification energy-saving process method and device

Technical Field

The invention relates to an energy-saving process method and device for rectifying methanol, which are used for producing methanol from crude methanol by a rectification process by adopting a four-tower three-effect heat integration device.

Background

Methanol is an important organic chemical raw material and a novel energy fuel, and has wide application in the fields of chemical industry, light industry and clean energy. In the industrial production process of synthetic methanol, the energy consumption of the refining process of crude methanol is one of the key factors influencing the production cost of methanol. Along with the increasing serious problems of shortage of energy resources such as petroleum, coal, natural gas and the like, environmental pollution, greenhouse effect and the like, the energy conservation and consumption reduction of industries such as methanol and the like become key for the survival of enterprises and the improvement of competitiveness, and the energy conservation and consumption reduction of industries such as methanol and the like are increasingly valued in various aspects.

Fig. 1 is a four-tower (three towers plus one tower) methanol rectification process widely adopted at present, namely, a recovery tower T104 is added to three towers such as a pre-tower T101, a pressurizing tower T102, an atmospheric tower T103 and the like, and a national standard high-grade or American standard AA-grade methanol product is produced. Removing light components from the top of the pre-tower, rectifying the crude methanol 10 after the distillation by a pressurizing tower and an atmospheric tower, respectively obtaining methanol products at the top discharge 24 of the pressurizing tower and the top discharge 14 of the atmospheric tower, and extracting the miscellaneous alcohol 42 from the side line of the atmospheric tower. The tower top material gas phase 21 of the pressurizing tower heats the tower bottom of the normal pressure tower. The impurity alcohol 42 at the side line of the rectifying tower and the kettle liquid 15 of the normal pressure tower enter a recovery tower, the recovered methanol product 29 is obtained from the top of the recovery tower, the impurity alcohol oil 30 is extracted from the side line of the recovery tower, and the wastewater 33 is discharged from the kettle of the recovery tower. Although the technology of the method is mature, the energy consumption of production is high, and the equipment is huge in scale as the scale of the device is increased. Is unfavorable for the construction, economy and stable operation of increasingly large methanol production devices.

Chinese patent CN 200610014321.2 discloses a process for rectifying and preparing high purity methanol, CN 200610013269.9 discloses a system and process for saving energy and saving water by double effect rectification of methanol, and the core content of both is based on the four-tower rectification process widely adopted at present, and the purpose of saving energy is achieved by utilizing the heat of condensate of heating steam or the heat exchange of cold and hot liquid in the system. It is apparent that the sensible heat transfer between such materials has very limited effect in reducing the operating energy consumption of the whole rectification system.

CN 200710067196.6 discloses a "synthetic methanol refining method with heat integration", which is characterized in that on the basis of the four-tower rectification process widely adopted at present, the gas phase at the top of the pressurizing tower is divided into two streams, and heat is provided for the pre-tower and the first rectifying tower respectively. Compared with CN 200610014321.2 and CN 200610013269.9, the process method has a higher energy-saving effect. However, as no methanol product is produced at the top of the pre-tower in the system, the energy provided by the pressurizing tower for the pre-tower belongs to the single-effect methanol rectification process. The pressurizing tower and the first rectifying tower in the system both produce methanol products, and only the pressurizing tower provides energy for the first rectifying tower, which belongs to the double-effect methanol rectifying process, so that the process method has certain improved energy-saving effect, but the energy-saving effect is not ideal.

CN 200710146369.3 discloses a "double-effect rectification method and apparatus for refining crude methanol under reduced pressure and countercurrent", which optimizes the operation conditions and rectification sequence of a pressurizing tower and a first rectifying tower in the four-tower rectification process widely adopted at present, crude methanol after light components are removed by a pre-tower is first introduced into a reduced pressure rectifying tower, the bottom liquid of the reduced pressure rectifying tower is introduced into a micro-pressurizing rectifying tower, and methanol products are obtained from the tops of the two towers. And heating the gas phase at the top of the micro-pressurization rectifying tower by a tower kettle reboiler of the vacuum rectifying tower. Although a reduced pressure rectification column is advantageous for increasing the relative volatility of the separation system and for obtaining higher methanol product purity. However, due to the lower boiling point of methanol, the temperature at the top of the tower is low due to the decompression operation, the heat exchange temperature difference of the condenser at the top of the tower is remarkably reduced, the area of the condenser is large, and meanwhile, the loss of methanol is possibly increased due to a vacuum system. It is known that such a depressurization process necessarily leads to a significant increase in the size of the corresponding column. For methanol plants that are currently becoming increasingly larger, this process can result in very large scale columns and heat exchange equipment. The essence of the technology still belongs to the double-effect rectification process of the traditional three-tower rectification, so that no substantial breakthrough can be made in the aspect of further reducing the energy consumption. The operation energy consumption of the pre-tower and the recovery tower is not counted, and the operation energy consumption is up to 0.916 ton of steam/ton of methanol product, and if the energy consumption of the pre-tower and the recovery tower is counted, the operation energy consumption is more than 1 ton of steam/ton of methanol product.

Disclosure of Invention

The invention aims to provide an energy-saving process method and device for rectifying four-tower three-effect methanol, which are energy-saving process methods for producing methanol from crude methanol through a rectification process, can overcome the defects of the prior art, reduce the operation energy consumption by more than 30 percent, have obvious practicability and economic benefit, and have wide application prospect.

The four-tower three-effect methanol rectification energy-saving process method provided by the invention comprises the following steps:

1) At least comprises four towers, namely a light component removal tower T201, a first rectifying tower T202, a second rectifying tower T203 and a third rectifying tower T204;

2) The side extracted gas phase of the first rectifying tower T202 enters the tower kettle of the light component removal tower T201, the tower kettle of the light component removal tower T201 does not need to provide heat by a reboiler, and the liquid phase material of the tower kettle of the light component removal tower T201 enters the first rectifying tower T202. The position of the side offtake gas phase of the first rectifying tower T202 can be near the feed inlet, above the feed inlet or below the feed inlet.

3) The lower part of the third rectifying tower T204 adopts a baffle tower structure, and the baffle S204 divides the lower part of the third rectifying tower T204 into a methanol stripping side L204 and an ethanol rectifying side R204;

4) The heat integration among the first rectifying tower T202, the second rectifying tower T203 and the third rectifying tower T204 is realized, and the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203;

5) Enriching and then discharging non-condensable gas 9 and light components 40 through the top of the light component removal tower T201;

6) Respectively extracting refined methanol products from the top or upper side line of the first rectifying tower T202, the top or upper side line of the second rectifying tower T203 and the top or upper side line of the third rectifying tower T204;

7) Discharging waste water 32 from the tower kettle of the L204 at the methanol stripping side of the third rectifying tower T204;

8) The fusel oil 28 with very low content of methanol and ethanol is laterally extracted from the vicinity of a feed inlet of the L204 on the methanol stripping side of the third rectifying tower T204;

9) Recovering ethanol product 35 from the third rectifying tower T204 ethanol rectifying side R204 tower kettle.

The process method provided by the invention comprises the following steps:

The crude methanol raw material 1 enters a light component removal tower T201 after being preheated.

The condensate 8 of the gas phase 7 at the top of the light component removal tower T201 condensed by the light component removal tower condenser E201 is used as reflux liquid to directly return to the top of the light component removal tower T201, and the noncondensable gas 9 is discharged; the side extracted gas 55 of the first rectifying tower T202 enters the tower kettle of the light component removal tower T201, the tower kettle of the light component removal tower T201 does not need a reboiler to provide heat, and the liquid phase material 36 of the tower kettle of the light component removal tower T201 enters the first rectifying tower T202. The position of the side offtake gas phase of the first rectifying tower T202 can be near the feed inlet, above the feed inlet or below the feed inlet.

The condensate 11 of the gas phase 10 at the top of the first rectifying tower T202 condensed by the first rectifying tower condenser E202 is divided into two parts, one part is taken as reflux liquid 12 to be directly returned to the top of the first rectifying tower T202, and the other part is taken as refined methanol product to be extracted; the upper part of the first rectifying tower T202 can also be provided with a side line outlet which is used as a refined methanol product outlet; the tower kettle material 14 of the first rectifying tower T202 enters the second rectifying tower T203.

The second rectifying tower T203 and the first rectifying tower T202 are subjected to heat integration operation, a gas phase 15 at the top of the second rectifying tower T203 enters a reboiler E203 shell pass of the first rectifying tower, a condensate 16 obtained by condensing the gas phase 15 at the top of the second rectifying tower T203 is divided into two parts, one part is taken as a reflux liquid 17 to be directly returned to the top of the second rectifying tower T203, and the other part is taken as a refined methanol product to be extracted; the upper part of the second rectifying tower T203 can also be provided with a side line outlet which is used as a refined methanol product outlet; and the tower bottom material 19 of the second rectifying tower T203 enters the methanol stripping side L204 of the third rectifying tower T204.

The third rectifying tower T204 and the second rectifying tower T203 are subjected to heat integration operation, a gas phase 20 at the top of the third rectifying tower T204 enters a shell pass of a reboiler E204 of the second rectifying tower, a condensate 21 obtained after condensation of the gas phase 20 at the top of the third rectifying tower T204 is divided into two parts, one part is taken as a reflux liquid 22 to be directly returned to the top of the third rectifying tower T204, and the other part is taken as a refined methanol product to be extracted; the upper part of the third rectifying tower T203 can also be provided with a side line outlet which is used as a refined methanol product outlet; the side line near the feed inlet of the L204 on the methanol stripping side of the third rectifying tower T204 is used for extracting fusel oil 27 with very low methanol and ethanol content; and the material 29 at the L204 tower kettle at the methanol stripping side of the third rectifying tower T204 is taken as waste water to be extracted, and the material 34 at the R204 tower kettle at the ethanol rectifying side of the third rectifying tower T204 is taken as recovered ethanol product to be extracted.

The refined methanol product 24 obtained by mixing the first rectifying tower T202 tower top product 13 or the tower upper side product, the second rectifying tower T203 tower top product 18 or the tower upper side product and the third rectifying tower T204 tower top product 23 or the tower upper side product is cooled to obtain the refined methanol product 26 which is sent out of the device.

The wastewater 31 obtained by cooling the wastewater 29 extracted from the bottom of the third rectifying tower T204 methanol stripping side L204 is divided into two parts, one part is taken as wastewater 32 to be sent out of the device, and the other part is taken as extraction water 33 to be returned to the top of the light component removal tower T201.

And cooling the fusel oil 27 extracted from the side line L204 of the methanol stripping side of the third rectifying tower T204 to obtain a fusel oil product 28, and sending the fusel oil product out of the device.

And cooling the recovered ethanol 34 extracted from the tower kettle of the R204 at the rectifying side of the ethanol in the third rectifying tower T204 to obtain a recovered ethanol product 35, and sending the recovered ethanol product out of the device.

According to the process method provided by the invention, besides the four-tower three-effect heat integration is adopted to produce methanol, the process method can be changed into other heat integration processes to produce methanol.

The deformation process method comprises the following steps: in the four towers, the third rectifying tower T204 does not adopt a baffle plate structure, but adopts a conventional structure, ethanol 34 is recovered by extracting the position above the feed inlet of the third rectifying tower T204, fusel oil 27 is extracted by extracting the position below the feed inlet, and tower bottom material 29 of the third rectifying tower T204 is extracted as wastewater.

And a deformation process method II: on the basis of the four towers, a stripping tower T206 is additionally arranged, and the third rectifying tower T204 adopts a conventional structure instead of a baffle structure. The five towers adopt three-effect heat integration, and the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203.

And a deformation process method III: in the above-mentioned four-column and the first four-column and the second five-column, the third rectifying column T204 is additionally provided with an intermediate heater E220 near the feed inlet, which may be in the form of a feed preheater or an intermediate reboiler, and the heat source used may be fresh steam, heat-conducting oil, or material steam generated in the system.

And a deformation process method is as follows: and the operation pressure of the four towers is adjusted, and the four towers are still subjected to three-effect heat integration operation. The operation pressure of the first rectifying tower T202 is unchanged, the second rectifying tower T203 is operated at high pressure, and the third rectifying tower T204 is operated at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the third rectifying tower T204, and provides the required heat for the third rectifying tower T204.

And a deformation process method: and the operation pressure of the four towers in the first deformation process method is adjusted, and the four towers are still subjected to three-effect heat integration operation. The operation pressure of the first rectifying tower T202 is unchanged, the second rectifying tower T203 is operated at high pressure, and the third rectifying tower T204 is operated at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the third rectifying tower T204, and provides the required heat for the third rectifying tower T204.

And a deformation process method is as follows: and adjusting the operating pressure of the five towers in the second deformation process method, wherein the operation is still five-tower three-effect heat integration operation. The first rectifying tower T202 has unchanged operation pressure, the second rectifying tower T203 operates at high pressure, and the third rectifying tower T204 and the stripping tower T206 operate at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the third rectifying tower T204 and the stripping tower T206, and provides the required heat for the third rectifying tower T204 and the stripping tower T206.

And a deformation process method seven: in the fourth tower of the deformation process method four and the fourth tower of the deformation process method five and the fifth tower of the deformation process method six, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E can be a feed preheater or an intermediate reboiler, and a heat source used can be a gas phase at the top of the second rectifying tower T203, or fresh steam, heat conducting oil or material steam generated in the system.

Eighth deformation process method: on the basis of four towers, one second rectifying tower T203 is reduced, three-tower double-effect heat integration operation is changed, and the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202, so that the required heat is provided for the first rectifying tower T202.

And a deformation process method nine: on the basis of four towers of the first deformation process method, one second rectifying tower T203 is reduced, the three-tower double-effect heat integration operation is changed, and the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower bottom of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202.

And a deformation process method is ten: on the basis of five towers of the second deformation process method, one second rectifying tower T203 is reduced, the four-tower double-effect heat integration operation is changed, and the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202, so that the required heat is provided for the first rectifying tower T202.

Eleven deformation process methods: in the third tower of the deformation process method eight, the third tower of the deformation process method nine and the fourth tower of the deformation process method ten, the third rectifying tower T204 is additionally provided with an intermediate heater E220 near the feed inlet, and the intermediate heater E can be a feed preheater or an intermediate reboiler, and the heat source used can be fresh steam, heat conducting oil or material steam generated in the system.

Twelve deformation process methods: in the four towers, a light component removal tower reboiler E213 is additionally arranged at the tower bottom of the light component removal tower T201, and the first rectifying tower T202 does not need side-cut extracted gas to enter the light component removal tower T201. The four towers adopt three-effect heat integration, and gas phases at the top of the second rectifying tower T203 are respectively used as heating sources of the tower bottoms of the first rectifying tower T202 and the light component removing tower T201 to respectively provide required heat for the first rectifying tower T202 and the light component removing tower T201; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203.

Thirteen deformation process methods: on the basis of the four towers, a recovery tower T207 is additionally arranged, and the third rectifying tower T204 adopts a conventional structure instead of a baffle structure. The heat integration among the first rectifying tower T202, the second rectifying tower T203 and the third rectifying tower T204 is realized, and the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203; recovery column T207 may employ the overhead vapor phase of second rectification column T203 or third rectification column T204 as a heat source, or other heat sources within the system, or an external heat source (e.g., live steam).

Fourteen deformation process methods: on the basis of the four towers, a waste water stripping tower T208 is additionally arranged, and the material at the L204 tower kettle at the methanol stripping side of the third rectifying tower T204 enters the top of the waste water stripping tower T208. When the pressure of the heating steam of the reboiler of the waste water stripping tower is enough, the gas phase 53 at the top of the waste water stripping tower T208 returns to the L204 tower kettle at the methanol stripping side of the third rectifying tower T204; when the pressure of the heating steam of the reboiler of the waste water stripping tower is insufficient, the gas phase at the top of the waste water stripping tower T208 can return to the bottom of the second rectifying tower T203 or the bottom of the first rectifying tower T202. And wastewater is extracted from the tower kettle of the wastewater stripping tower T208. The heat source used by the reboiler of the waste water stripping tower can be fresh steam, conduction oil or material steam generated in the system.

Fifteen deformation process methods: and the operating pressure and the heat integration sequence of the four towers described in the twelfth deformation process method are adjusted, and the four towers are still subjected to three-effect heat integration. The first rectifying tower T202 is operated at high pressure, and the second rectifying tower T203 is operated at low pressure. The gas phase at the top of the first rectifying tower T202 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203; the gas phase at the top of the second rectifying tower T203 is used as a heating source for tower bottoms of the light component removal tower T201 and the third rectifying tower T204, and provides required heat for the light component removal tower T201 and the third rectifying tower T204.

Sixteen deformation process methods: and the operating pressure and the heat integration sequence of the four towers described in the twelfth deformation process method are adjusted, and the four towers are still subjected to three-effect heat integration. The first rectifying column T202 is operated at high pressure, and the third rectifying column T204 is operated at low pressure. The gas phase at the top of the first rectifying tower T202 is used as a heating source of the tower kettle of the third rectifying tower T204, and the required heat is provided for the third rectifying tower T204; the gas phase at the top of the third rectifying tower T204 is used as a heating source of tower bottoms of the light component removal tower T201 and the second rectifying tower T203, and provides required heat for the light component removal tower T201 and the second rectifying tower T203.

According to the process method provided by the invention, in order to reduce the operation energy consumption, the energy-saving method can be adopted as follows:

1) The crude methanol raw material can exchange heat with wastewater discharged from the tower kettle of the L204 at the methanol stripping side of the third rectifying tower T204, the crude methanol raw material can also exchange heat with a methanol product, and the crude methanol raw material can also exchange heat with the gas phase at the tower top of the first rectifying tower T202 or the light component removal tower T201;

2) The feeding materials of the first rectifying tower T202, the second rectifying tower T203, the third rectifying tower T204, the light component removing tower T201 and other towers exchange heat with the heating steam condensate.

Typical embodiments of this heat exchange between the steam condensate and the feed to each column are:

The steam condensate exchanges heat with the feed of the third rectifying tower T204, and the feed of the third rectifying tower T204 is preheated;

Feeding the steam condensate subjected to heat exchange to the third rectifying tower T204, feeding the steam condensate to the second rectifying tower T203, and preheating the feeding of the second rectifying tower T203;

feeding the steam condensate subjected to heat exchange to the second rectifying tower T203, then feeding the steam condensate to the first rectifying tower T202 for heat exchange, and preheating the feeding of the first rectifying tower T202;

and feeding the steam condensate subjected to heat exchange to the first rectifying tower T202, then feeding the steam condensate to the light component removal tower T201 for heat exchange, and preheating the light component removal tower T201 for feeding.

The heat exchange mode between the steam condensate and the feeding materials of each tower can be one of the above combinations or a combination of some heat exchange modes. The heat exchange mode is only complementary to the energy-saving process method for rectifying methanol by the four-tower three-effect heat integration device provided by the invention, but not limited to the spirit of the invention, and a person skilled in the relevant art can completely perform the arrangement and combination of the heat exchange processes according to common general knowledge, so that various evolution process flows formed by the arrangement and combination of the heat exchange processes are considered to be in the spirit, the scope and the content of the invention.

According to the process method provided by the invention, an absorption tower T205 can be additionally arranged on the basis of the four-tower three-effect heat integration (or five-tower three-effect heat integration or three-tower double-effect heat integration), and tail gas of the light component removal tower T201 is absorbed by washing water in the absorption tower T205 and then discharged out of the device, so that methanol in the tail gas is recovered, the yield of methanol products is improved, and the pollutant content in discharged noncondensable gas is reduced. The addition of the absorption tower T205 is a general method, and any method or a modification method thereof provided by the invention can be adopted to improve the yield of methanol products and reduce the pollutant content in the discharged noncondensable gas. When the general method is adopted, a part of extraction water can be fed into the top of the light component removal tower T201 from 33; another part 37 enters the top of the absorption tower T205; the extract water may also be fed entirely into the top of the absorption column T205.

According to the process method provided by the invention, the top products 13, 18 and 23 of the first rectifying tower T202, the second rectifying tower T203 and the third rectifying tower T204 can be extracted from the side lines at the upper parts of the towers.

According to the process provided by the invention, the heat source used by the third rectifying tower reboilers E205 and E206 can be fresh steam, heat conducting oil or material steam generated in the system.

According to the process method provided by the invention, the discharge material of the tower bottom of the light component removal tower T201 can be firstly introduced into the first rectifying tower T202, or firstly introduced into the second rectifying tower T203, or firstly introduced into the third rectifying tower T204.

The technical method and the device for rectifying the methanol by adopting the four-tower three-effect heat integration (or five-tower three-effect heat integration or three-tower double-effect heat integration) device can be used for producing national standard high-grade methanol, american standard AA-grade methanol products or methanol products with other specifications.

According to the process provided by the invention, typical operating conditions of each tower are as follows:

The operating pressure range of the top of the light component removal tower T201 is 30-195 kPa;

the operating pressure range of the top of the first rectifying tower T202 is 30-195 kPa;

the operating pressure range of the top of the second rectifying tower T203 is 160-950 kPa;

The operating pressure range of the top of the third rectifying tower T204 is 310-1500 kPa.

All pressures in this invention are absolute unless specifically indicated.

According to the process provided by the invention, the preferred operating conditions of each column are:

the tower top operation pressure of the light component removing tower T201 is 80-150 kpa, the tower top operation temperature is 50-85 ℃, and the tower bottom operation temperature is 55-90 ℃;

the operation pressure of the top of the first rectifying tower T202 is 80-180 kpa, the operation temperature of the top of the tower is 50-90 ℃, and the operation temperature of the bottom of the tower is 55-100 ℃;

the operating pressure of the top of the second rectifying tower T203 is 160-500 kPa, the operating temperature of the top of the tower is 70-130 ℃, and the operating temperature of the bottom of the tower is 75-140 ℃.

The top operation pressure of the third rectifying tower T204 is 400-900 kPa, the top operation temperature is 90-150 ℃, and the operation temperature of the tower kettle of the methanol stripping side L204 is 135-180 ℃; the operating temperature of the tower kettle of the R204 tower at the ethanol rectifying side is 110-160 ℃.

The invention provides an energy-saving device for rectifying methanol by adopting a four-tower three-effect heat integration device, which comprises: four towers of a light component removal tower T201, a first rectifying tower T202, a second rectifying tower T203, a third rectifying tower T204 and the like and connecting pipelines.

The raw material crude methanol feed pipeline is respectively connected with the cold side inlets of the feed methanol preheater and the feed wastewater preheater.

The cold side outlets of the feed methanol preheater and the feed wastewater preheater are connected to the middle part of the light component removal tower T201; the top of the light component removal tower T201 is connected with a light component removal tower condenser, a condensate outlet of the light component removal tower condenser is connected with the top of the light component removal tower T201, and a noncondensable gas outlet of the light component removal tower condenser is connected with a noncondensable gas discharge pipeline; the bottom of the light component removal tower T201 is connected with a first rectifying tower T202 by a plurality of pipelines.

The top of the first rectifying tower T202 is connected with a first rectifying tower condenser, and a condensate outlet of the first rectifying tower condenser is respectively connected with the top of the first rectifying tower T202 and a hot side inlet of the feed methanol preheater; the side line gas phase extraction port of the first rectifying tower T202 is connected with the tower kettle of the light component removal tower T201; the bottom of the first rectifying tower T202 is respectively connected with a first rectifying tower reboiler tube pass inlet and a second rectifying tower T203, and a first rectifying tower reboiler tube pass outlet is connected to a first rectifying tower T202 tower kettle.

The top of the second rectifying tower T203 is connected with the reboiler shell side of the first rectifying tower, and the condensate outlet of the reboiler shell side of the first rectifying tower is respectively connected with the top of the second rectifying tower T203 and the hot side inlet of the feed methanol preheater; the bottom of the second rectifying tower T203 is respectively connected with a second rectifying tower reboiler tube pass inlet and a third rectifying tower T204, and a second rectifying tower reboiler tube pass outlet is connected to a second rectifying tower T203 tower kettle.

The top of the third rectifying tower T204 is connected with the reboiler shell side of the second rectifying tower, and the condensate outlet of the reboiler shell side of the second rectifying tower is respectively connected with the top of the third rectifying tower T204 and the hot side inlet of the feed methanol preheater; the bottom of the methanol stripping side L204 of the third rectifying tower T204 is respectively connected with a tube side inlet of a reboiler of the methanol stripping side of the third rectifying tower and a hot side inlet of a feed wastewater preheater, and a tube side outlet of the reboiler of the methanol stripping side of the third rectifying tower is connected to a kettle of the methanol stripping side L204 of the third rectifying tower T204; a side line extraction pipeline near the feeding of the methanol stripping side L204 of the third rectifying tower T204 is connected with a hot side inlet of the fusel oil cooler; the bottom of the ethanol rectifying side R204 of the third rectifying tower T204 is respectively connected with a tube side inlet of an ethanol rectifying side reboiler of the third rectifying tower and a hot side inlet of an ethanol cooler, and a tube side outlet of the ethanol rectifying side reboiler of the third rectifying tower is connected to a tower kettle of the ethanol rectifying side R204 of the third rectifying tower T204.

The hot side outlet of the feed methanol preheater is connected with the hot side inlet of the methanol product cooler, and the hot side outlet of the methanol product cooler is connected with the methanol product extraction pipeline.

The hot side outlet of the feeding wastewater preheater is connected with the hot side inlet of the wastewater cooler, and the hot side outlet of the wastewater cooler is respectively connected with the top of the light component removal tower T201 and the wastewater discharge pipeline.

And the hot side outlet of the fusel oil cooler is connected with a fusel oil product extraction pipeline.

The hot side outlet of the ethanol cooler is connected with an ethanol product extraction pipeline.

The invention relates to an energy-saving process method and device for rectifying methanol, which are used for producing methanol from crude methanol by a rectification process by adopting a four-tower three-effect heat integration device. The whole device at least comprises four towers of a light component removal tower T201, a first rectifying tower T202, a second rectifying tower T203, a third rectifying tower T204 and the like and matched equipment thereof. The invention adopts a multi-tower heat integration process method, can overcome the defects of the prior art, reduces the operation energy consumption by more than 30 percent, has obvious practicality and economic benefit, and has wide application prospect.

Drawings

FIG. 1 is a flow chart of a four-column (three columns plus one column) methanol rectification process employed in the prior art.

Fig. 2 is a process flow diagram of a typical four-tower three-effect heat integration device for rectifying methanol.

Fig. 3 shows an evolution process of fig. 2, namely a deformation process 1. In the four-tower three-effect heat integration shown in fig. 2, the third rectifying tower T204 does not adopt a partition plate structure, but adopts a conventional structure, ethanol 34 is recovered by extraction at a position above a feed inlet of the third rectifying tower T204, fusel oil 27 is extracted at a position below the feed inlet, and tower bottom material 29 of the third rectifying tower T204 is extracted as wastewater.

Fig. 4 shows an evolution process of fig. 2, namely a deformation process two. The four-tower three-effect heat integration operation shown in fig. 2 is changed into five-tower three-effect heat integration to produce methanol. A stripping tower T206 is additionally arranged on the basis of four towers, and the third rectifying tower T204 adopts a conventional structure instead of a baffle structure. The five towers adopt three-effect heat integration, and the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203.

Fig. 5 is an evolution process of fig. 2, namely, a deformation process of three. In the four-tower three-effect heat integration shown in fig. 2, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, and a heat source used may be live steam, heat conducting oil or material steam generated in the system.

Fig. 6 is an evolution process of fig. 3, namely, a deformation process three. In the four-tower three-effect heat integration shown in fig. 3, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the form of the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be live steam, heat conducting oil or material steam generated in the system.

Fig. 7 is an evolution process of fig. 4, namely, a deformation process of three. In the five-tower three-effect heat integration shown in fig. 4, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be live steam, heat conducting oil or material steam generated in the system.

Fig. 8 is an evolution process of fig. 2, namely, a deformation process of fourth. The operating pressure of the four-tower three-effect heat integration shown in fig. 2 is adjusted, and the four-tower three-effect heat integration operation is still performed. The operation pressure of the first rectifying tower T202 is unchanged, the second rectifying tower T203 is operated at high pressure, and the third rectifying tower T204 is operated at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the third rectifying tower T204, and provides the required heat for the third rectifying tower T204.

Fig. 9 is an evolution process of fig. 3, namely, a deformation process five. The operating pressure of the four-tower three-effect heat integration shown in fig. 3 is adjusted, and the four-tower three-effect heat integration operation is still performed. The operation pressure of the first rectifying tower T202 is unchanged, the second rectifying tower T203 is operated at high pressure, and the third rectifying tower T204 is operated at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the third rectifying tower T204, and provides the required heat for the third rectifying tower T204.

Fig. 10 is an evolution process of fig. 4, namely, a deformation process six. The five-tower three-effect heat integration operation shown in fig. 4 is still performed by adjusting the operation pressure. The first rectifying tower T202 has unchanged operation pressure, the second rectifying tower T203 operates at high pressure, and the third rectifying tower T204 and the stripping tower T206 operate at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the third rectifying tower T204 and the stripping tower T206, and provides the required heat for the third rectifying tower T204 and the stripping tower T206.

Fig. 11 is an evolution process of fig. 8, namely, a deformation process seven. In the four-tower three-effect heat integration shown in fig. 8, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, a gas phase at the top of the second rectifying tower T203, live steam, heat conducting oil or material steam generated in the system.

Fig. 12 is an evolution process of fig. 9, namely, a deformation process seven. In the four-tower three-effect heat integration shown in fig. 9, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, a gas phase at the top of the second rectifying tower T203, live steam, heat conducting oil or material steam generated in the system.

Fig. 13 is an evolution process of fig. 10, namely, a deformation process seven. In the five-tower three-effect heat integration shown in fig. 10, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, a gas phase at the top of the second rectifying tower T203, live steam, heat conducting oil or material steam generated in the system.

Fig. 14 is an evolution process of fig. 2, namely, a deformation process eight. The four-tower three-effect heat integration shown in fig. 2 is changed into three-tower double-effect heat integration operation by reducing a second rectifying tower T203, and the gas phase at the top of a third rectifying tower T204 is used as a heating source of a tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202.

Fig. 15 is an evolution process of fig. 3, namely, a deformation process nine. The four-tower three-effect heat integration shown in fig. 3 is changed into three-tower double-effect heat integration operation by reducing one second rectifying tower T203, and the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower bottom of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202.

Fig. 16 is an evolution process of fig. 4, namely, a deformation process ten. On the basis of five-tower three-effect heat integration shown in fig. 4, one second rectifying tower T203 is reduced, four-tower double-effect heat integration operation is changed, and a gas phase at the top of a third rectifying tower T204 is used as a heating source of a tower kettle of the first rectifying tower T202 to provide required heat for the first rectifying tower T202.

Fig. 17 is an evolution process of fig. 14, namely, a deformation process eleven. In the three-tower double-effect heat integration shown in fig. 14, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the form of the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be fresh steam, heat conducting oil or material steam generated in the system.

Fig. 18 is an evolution process of fig. 15, namely, a deformation process eleven. In the three-tower double-effect heat integration shown in fig. 15, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the form of the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be fresh steam, heat conducting oil or material steam generated in the system.

Fig. 19 is an evolution process of fig. 16, namely, a deformation process eleven. In the four-tower double-effect heat integration shown in fig. 16, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the form of the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be fresh steam, heat conducting oil or material steam generated in the system.

Fig. 20 is an evolution process of fig. 2, namely, a deformation process twelve. In the four-tower three-effect heat integration shown in fig. 2, a light component removal tower reboiler E213 is additionally arranged at the tower bottom of the light component removal tower T201, and the first rectifying tower T202 does not need side-draw gas phase to enter the light component removal tower T201. The four towers adopt three-effect heat integration, and gas phases at the top of the second rectifying tower T203 are respectively used as heating sources of the tower bottoms of the first rectifying tower T202 and the light component removing tower T201 to respectively provide required heat for the first rectifying tower T202 and the light component removing tower T201; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203.

Fig. 21 is a diagram of an evolution process of fig. 2, namely, a deformation process of thirteen. The four-tower three-effect heat integration shown in fig. 2 is changed into five-tower three-effect heat integration to produce methanol. On the basis of four towers, a recovery tower T207 is additionally arranged, and the third rectifying tower T204 adopts a conventional structure instead of a partition plate structure. The heat integration among the first rectifying tower T202, the second rectifying tower T203 and the third rectifying tower T204 is realized, and the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203; recovery column T207 may employ the overhead vapor phase of second rectification column T203 or third rectification column T204 as a heat source, or other heat sources within the system, or an external heat source (e.g., live steam).

Fig. 22 is a diagram of an evolution process, namely, a deformation process fourteen, of fig. 2. The four-tower three-effect heat integration shown in fig. 2 is changed into five-tower three-effect heat integration to produce methanol. On the basis of four towers, a waste water stripping tower T208 is additionally arranged, and the material at the L204 tower kettle at the methanol stripping side of the third rectifying tower T204 enters the top of the waste water stripping tower T208. When the pressure of the heating steam of the reboiler of the waste water stripping tower is enough, the gas phase 53 at the top of the waste water stripping tower T208 returns to the L204 tower kettle at the methanol stripping side of the third rectifying tower T204; when the pressure of the heating steam of the reboiler of the waste water stripping tower is insufficient, the gas phase at the top of the waste water stripping tower T208 can return to the bottom of the second rectifying tower T203 or the bottom of the first rectifying tower T202. And wastewater is extracted from the tower kettle of the wastewater stripping tower T208. The heat source used by the reboiler of the waste water stripping tower can be fresh steam, conduction oil or material steam generated in the system.

Fig. 23 is a diagram of an evolving process of fig. 20, namely, a deforming process fifteen. The operating pressure and heat integration sequence of the four-tower three-effect heat integration shown in fig. 20 are adjusted, and the four-tower three-effect heat integration is still realized. The first rectifying tower T202 is operated at high pressure, and the second rectifying tower T203 is operated at low pressure. The gas phase at the top of the first rectifying tower T202 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203; the gas phase at the top of the second rectifying tower T203 is used as a heating source for tower bottoms of the light component removal tower T201 and the third rectifying tower T204, and provides required heat for the light component removal tower T201 and the third rectifying tower T204.

Fig. 24 is a diagram of an evolving process of fig. 20, namely a deforming process sixteen. The operating pressure and heat integration sequence of the four-tower three-effect heat integration shown in fig. 20 are adjusted, and the four-tower three-effect heat integration is still realized. The first rectifying column T202 is operated at high pressure, and the third rectifying column T204 is operated at low pressure. The gas phase at the top of the first rectifying tower T202 is used as a heating source of the tower kettle of the third rectifying tower T204, and the required heat is provided for the third rectifying tower T204; the gas phase at the top of the third rectifying tower T204 is used as a heating source of tower bottoms of the light component removal tower T201 and the second rectifying tower T203, and provides required heat for the light component removal tower T201 and the second rectifying tower T203.

Fig. 25 is a diagram showing an evolution process method of fig. 2, wherein an absorption tower T205 is additionally arranged on the basis of the four-tower three-effect heat integration operation shown in fig. 2, tail gas at the top of the light component removal tower T201 is absorbed by washing water in the absorption tower T205 and then discharged out of the device, so as to recover methanol in the tail gas, improve the yield of methanol products and reduce the content of pollutants in discharged noncondensable gas.

Fig. 26 is a diagram showing an evolution process of fig. 20, wherein an absorber T205 is added on the basis of the four-tower three-effect heat integration operation shown in fig. 20, and tail gas at the top of the light component removal tower T201 is absorbed by washing water in the absorber T205 and then discharged out of the device, so as to recover methanol therein, improve the yield of methanol products and reduce the content of pollutants in discharged noncondensable gas.

Fig. 27 shows an evolution process of fig. 26, in which the bottom discharge of the light component removal tower T201 shown in fig. 26 is introduced into the first rectifying tower T202 and is introduced into the second rectifying tower T203.

Detailed Description

Specific embodiments of the invention are described in detail below with reference to the drawings, but are merely illustrative of the invention and not limiting.

Unless specifically indicated, the composition, structure, materials (connecting lines for connecting the respective columns, etc.), reagents, etc. of the process equipment such as the columns, etc. which are not specifically used in the examples, are commercially available or can be obtained by a method well known to those skilled in the art. The specific experimental methods, operating conditions involved are generally as set forth in conventional process conditions as well as in handbooks, or as recommended by the manufacturer.

The invention provides an energy-saving process method for rectifying methanol by adopting a four-tower three-effect heat integration device, which comprises the following steps:

The process method provided by the invention comprises the following specific steps:

raw methanol raw material 1 is divided into two strands 2 and 3, raw material 2 is preheated by a feed wastewater preheater E208 to be raw material 4, raw material 3 is preheated by a feed methanol preheater E207 to be raw material 5, and preheated raw materials 4 and 5 are mixed to be raw material 6 to enter a light component removal tower T201.

The condensate 11 of the gas phase 10 at the top of the first rectifying tower T202 condensed by the first rectifying tower condenser E202 is divided into two streams, one stream is taken as reflux liquid 12 to be directly returned to the top of the first rectifying tower T202, and the other stream of condensate 13 is taken as refined methanol product to be extracted to a feed methanol preheater E207; the tower kettle material 14 of the first rectifying tower T202 enters the second rectifying tower T203.

The second rectifying tower T203 and the first rectifying tower T202 are subjected to heat integration operation, a gas phase 15 at the top of the second rectifying tower T203 enters a shell pass of a reboiler E203 of the first rectifying tower, a condensate 16 after the gas phase 15 at the top of the second rectifying tower T203 is condensed is divided into two parts, one part is taken as a reflux liquid 17 to be directly returned to the top of the second rectifying tower T203, and the other part of condensate 18 is taken as a refined methanol product to be extracted to a feed methanol preheater E207; and the tower bottom material 19 of the second rectifying tower T203 enters the methanol stripping side L204 of the third rectifying tower T204.

The third rectifying tower T204 and the second rectifying tower T203 are subjected to heat integration operation, a gas phase 20 at the top of the third rectifying tower T204 enters a shell pass of a reboiler E204 of the second rectifying tower, a condensate 21 after the gas phase 20 at the top of the third rectifying tower T204 is condensed is divided into two parts, one part is taken as a reflux liquid 22 to be directly returned to the top of the third rectifying tower T204, and the other part of condensate 23 is taken as a refined methanol product to be extracted to a feed methanol preheater E207; the fusel oil 27 with very low content of methanol and ethanol is laterally extracted near the feed inlet of the L204 on the methanol stripping side of the third rectifying tower T204 to a fusel oil cooler E211; and the material 29 at the tower bottom of the L204 at the methanol stripping side of the third rectifying tower T204 is taken as wastewater to be extracted to a feed wastewater preheater E208, and the material 34 at the tower bottom of the R204 at the ethanol rectifying side of the third rectifying tower T204 is taken as recovered ethanol product to be extracted to an ethanol cooler E212.

The refined methanol product 24 obtained by mixing the top product 13 of the first rectifying tower T202, the top product 18 of the second rectifying tower T203 and the top product 23 of the third rectifying tower T204 is subjected to heat exchange with the crude methanol raw material 3 through a feed methanol preheater E207 to obtain a refined methanol product 25, and is cooled through a methanol product cooler E209 to obtain a refined methanol product 26 which is sent out of the device.

Waste water 29 extracted from the bottom of the L204 tower at the methanol stripping side of the third rectifying tower T204 is subjected to heat exchange with the crude methanol raw material 2 through a feed waste water preheater E208 to obtain waste water 30, and then the waste water 31 obtained after cooling through a waste water cooler E210 is divided into two parts, one part is taken as waste water 32 to be sent out of the device, and the other part is taken as extraction water 33 to be returned to the top of the light component removal tower T201.

And the fusel oil 27 extracted from the side line L204 of the methanol stripping side of the third rectifying tower T204 is cooled by a fusel oil cooler E211 to obtain a fusel oil product 28, and the fusel oil product is sent out of the device.

And cooling the recovered ethanol 34 extracted from the tower kettle of the rectifying side R204 of the ethanol in the third rectifying tower T204 by an ethanol cooler E212 to obtain a recovered ethanol product 35, and sending the recovered ethanol product out of the device.

The typical crude methanol feed composition for the process provided by the invention is:

the mass percent of the components is (%)

Carbon monoxide 0.07

Carbon dioxide 1.01

Methanol 96.04

Water 2.22

Ethanol 0.15

Dimethyl ether 0.10

Methyl formate 0.15

Acetone 0.01

N-propanol 0.02

N-butanol 0.02

Isobutanol 0.03

N-amyl alcohol 0.01

Isoamyl alcohol 0.01

Sec-amyl alcohol 0.01

N-pentane 0.03

N-hexane 0.08

N-heptane 0.04

Totaling to 100.00.

The above ranges of raw material composition do not constitute any limitation to the present invention, which can be used for the rectification of raw methanol raw materials of various compositions.

Application example 1:

As shown in fig. 2, the raw methanol feed 1 is divided into two streams 2 and 3, the feed 2 is preheated by a feed wastewater preheater E208 to be feed 4, the feed 3 is preheated by a feed methanol preheater E207 to be feed 5, and the preheated feeds 4 and 5 are mixed to be feed 6 to enter a light component removal tower T201.

The heat sources used by the third rectifying tower methanol stripping side reboiler E205 and the third rectifying tower ethanol rectifying side reboiler E206 can be conventional heat sources such as fresh steam, heat conducting oil and the like or material steam generated in the system.

The condensate of the fresh steam added by the system can be preheated for each tower feed separately or sequentially.

Preferred operating conditions for each column in example 1 are given below:

One typical operating condition and operating energy consumption for each column in example 1 is given below:

The operating pressure at the top of the light component removal column T201 is 110kpa, the operating temperature at the top of the column is 71 ℃, and the operating temperature at the bottom of the column is 74 ℃.

The operation pressure at the top of the first rectifying tower T202 is 130kpa, the operation temperature at the top of the tower is 71 ℃, and the operation temperature at the bottom of the tower is 79 ℃;

The second rectification column T203 has a top operating pressure of 320kPa, a top operating temperature of 97℃and a bottom operating temperature of 109 ℃.

The top operation pressure of the third rectifying tower T204 is 750kPa, the top operation temperature is 126 ℃, and the bottom operation temperature of the methanol stripping side L204 is 169 ℃; the operating temperature of the tower kettle of the ethanol rectifying side R204 is 139 ℃.

The whole methanol rectifying device only needs external heating sources for reboilers (E205 and E206) at the bottom of the third rectifying tower T204, and other heat sources needed by reboilers, preheaters and the like can be heated by utilizing internal heat sources of the system and steam condensate.

Considering the external heating source according to medium pressure steam, the device scale is according to 60 ten thousand tons of American standard AA-level refined methanol products (the operation time is 7200 hours/year) produced annually, and according to the four-tower methanol rectification technology widely adopted at present, the minimum steam consumption in the methanol rectification process is 1 ton of steam/ton of refined methanol products; the technical method for rectifying the methanol by adopting the four-tower three-effect heat integration device provided by the invention has the advantages that the steam consumption of the device is lower than 58 tons/hour, and the steam unit consumption is lower than 0.7 ton of steam/ton of refined methanol product.

Steam savings are about:

(1-0.7) ton/ton×60 ten thousand ton/year=18 ten thousand ton/year.

Steam cost can be saved every year by calculating 150 yuan per ton of steam:

18 ten thousand tons/year x 150 yuan/ton = 2700 ten thousand yuan/year.

The process method and the device for rectifying the methanol by using the four-tower three-effect heat integration device have extremely remarkable economic benefits.

Application example 2:

As shown in fig. 3, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

In the four-tower three-effect heat integration shown in fig. 2, the third rectifying tower T204 does not adopt a partition plate structure, but adopts a conventional structure, ethanol 34 is recovered by extraction at a position above a feed inlet of the third rectifying tower T204, fusel oil 27 is extracted at a position below the feed inlet, and tower bottom material 29 of the third rectifying tower T204 is extracted as wastewater.

Application example 3:

As shown in fig. 4, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

The four-tower three-effect heat integration operation shown in fig. 2 is changed into five-tower three-effect heat integration to produce methanol. A stripping tower T206 is additionally arranged on the basis of four towers, and the third rectifying tower T204 adopts a conventional structure instead of a baffle structure. The five towers adopt three-effect heat integration, and the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203.

Application example 4:

As shown in fig. 5, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

In the four-tower three-effect heat integration shown in fig. 2, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, and a heat source used may be live steam, heat conducting oil or material steam generated in the system.

Application example 5:

as shown in fig. 6, it is an evolution process of fig. 3, and the difference with respect to the process shown in fig. 3 is that:

In the four-tower three-effect heat integration shown in fig. 3, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the form of the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be live steam, heat conducting oil or material steam generated in the system.

Application example 6:

As shown in fig. 7, it is an evolution process of fig. 4, and the difference with respect to the process shown in fig. 4 is that:

In the five-tower three-effect heat integration shown in fig. 4, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be live steam, heat conducting oil or material steam generated in the system.

Application example 7:

As shown in fig. 8, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

the operating pressure of the four-tower three-effect heat integration shown in fig. 2 is adjusted, and the four-tower three-effect heat integration operation is still performed. The operation pressure of the first rectifying tower T202 is unchanged, the second rectifying tower T203 is operated at high pressure, and the third rectifying tower T204 is operated at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the third rectifying tower T204, and provides the required heat for the third rectifying tower T204.

Application example 8:

as shown in fig. 9, it is an evolution process of fig. 3, and the difference with respect to the process shown in fig. 3 is that:

The operating pressure of the four-tower three-effect heat integration shown in fig. 3 is adjusted, and the four-tower three-effect heat integration operation is still performed. The operation pressure of the first rectifying tower T202 is unchanged, the second rectifying tower T203 is operated at high pressure, and the third rectifying tower T204 is operated at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the third rectifying tower T204, and provides the required heat for the third rectifying tower T204.

Application example 9:

as shown in fig. 10, it is an evolution process of fig. 4, and the difference with respect to the process shown in fig. 4 is that:

The five-tower three-effect heat integration operation shown in fig. 4 is still performed by adjusting the operation pressure. The first rectifying tower T202 has unchanged operation pressure, the second rectifying tower T203 operates at high pressure, and the third rectifying tower T204 and the stripping tower T206 operate at low pressure. The gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the second rectifying tower T203 is used as a heating source of the third rectifying tower T204 and the stripping tower T206, and provides the required heat for the third rectifying tower T204 and the stripping tower T206.

Application example 10:

as shown in fig. 11, it is an evolution process of fig. 8, and the difference with respect to the process shown in fig. 8 is that:

In the four-tower three-effect heat integration shown in fig. 8, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, a gas phase at the top of the second rectifying tower T203, live steam, heat conducting oil or material steam generated in the system.

Application example 11:

as shown in fig. 12, it is an evolution process of fig. 9, and the difference with respect to the process shown in fig. 9 is that:

In the four-tower three-effect heat integration shown in fig. 9, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, a gas phase at the top of the second rectifying tower T203, live steam, heat conducting oil or material steam generated in the system.

Application example 12:

As shown in fig. 13, it is an evolution process of fig. 10, which is different from the process shown in fig. 10 in that:

in the five-tower three-effect heat integration shown in fig. 10, an intermediate heater E220 is additionally arranged near a feed inlet of the third rectifying tower T204, and the intermediate heater E may be a feed preheater, an intermediate reboiler, a gas phase at the top of the second rectifying tower T203, live steam, heat conducting oil or material steam generated in the system.

Application example 13:

As shown in fig. 14, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

The four-tower three-effect heat integration shown in fig. 2 is changed into three-tower double-effect heat integration operation by reducing a second rectifying tower T203, and the gas phase at the top of a third rectifying tower T204 is used as a heating source of a tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202.

Application example 14:

as shown in fig. 15, it is an evolution process of fig. 3, and the difference with respect to the process shown in fig. 3 is that:

the four-tower three-effect heat integration shown in fig. 3 is changed into three-tower double-effect heat integration operation by reducing one second rectifying tower T203, and the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower bottom of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202.

Application example 15:

as shown in fig. 16, it is an evolution process of fig. 4, and the difference with respect to the process shown in fig. 4 is that:

On the basis of five-tower three-effect heat integration shown in fig. 4, one second rectifying tower T203 is reduced, four-tower double-effect heat integration operation is changed, and a gas phase at the top of a third rectifying tower T204 is used as a heating source of a tower kettle of the first rectifying tower T202 to provide required heat for the first rectifying tower T202.

Application example 16:

As shown in fig. 17, it is an evolution process of fig. 14, and the difference with respect to the process shown in fig. 14 is that:

In the three-tower double-effect heat integration shown in fig. 14, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the form of the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be fresh steam, heat conducting oil or material steam generated in the system.

Application example 17:

as shown in fig. 18, it is an evolution process of fig. 15, and the difference with respect to the process shown in fig. 15 is that:

In the three-tower double-effect heat integration shown in fig. 15, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the form of the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be fresh steam, heat conducting oil or material steam generated in the system.

Application example 18:

As shown in fig. 19, it is an evolution process of fig. 16, and the difference with respect to the process shown in fig. 16 is that:

In the four-tower double-effect heat integration shown in fig. 16, an intermediate heater E220 is additionally arranged near the feed inlet of the third rectifying tower T204, and the form of the intermediate heater E may be a feed preheater, an intermediate reboiler, and the heat source used may be fresh steam, heat conducting oil or material steam generated in the system.

Application example 19:

as shown in fig. 20, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

in the four-tower three-effect heat integration shown in fig. 2, a light component removal tower reboiler E213 is additionally arranged at the tower bottom of the light component removal tower T201, and the first rectifying tower T202 does not need side-draw gas phase to enter the light component removal tower T201. The four towers adopt three-effect heat integration, and gas phases at the top of the second rectifying tower T203 are respectively used as heating sources of the tower bottoms of the first rectifying tower T202 and the light component removing tower T201 to respectively provide required heat for the first rectifying tower T202 and the light component removing tower T201; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203.

Application example 20:

as shown in fig. 21, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

The four-tower three-effect heat integration shown in fig. 2 is changed into five-tower three-effect heat integration to produce methanol. On the basis of four towers, a recovery tower T207 is additionally arranged, and the third rectifying tower T204 adopts a conventional structure instead of a partition plate structure. The heat integration among the first rectifying tower T202, the second rectifying tower T203 and the third rectifying tower T204 is realized, and the gas phase at the top of the second rectifying tower T203 is used as a heating source of the tower kettle of the first rectifying tower T202 to provide the required heat for the first rectifying tower T202; the gas phase at the top of the third rectifying tower T204 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203; recovery column T207 may employ the overhead vapor phase of second rectification column T203 or third rectification column T204 as a heat source, or other heat sources within the system, or an external heat source (e.g., live steam).

Application example 21:

As shown in fig. 22, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

The four-tower three-effect heat integration shown in fig. 2 is changed into five-tower three-effect heat integration to produce methanol. On the basis of four towers, a waste water stripping tower T208 is additionally arranged, and the material at the L204 tower kettle at the methanol stripping side of the third rectifying tower T204 enters the top of the waste water stripping tower T208. When the pressure of the heating steam of the reboiler of the waste water stripping tower is enough, the gas phase 53 at the top of the waste water stripping tower T208 returns to the L204 tower kettle at the methanol stripping side of the third rectifying tower T204; when the pressure of the heating steam of the reboiler of the waste water stripping tower is insufficient, the gas phase at the top of the waste water stripping tower T208 can return to the bottom of the second rectifying tower T203 or the bottom of the first rectifying tower T202. And wastewater is extracted from the tower kettle of the wastewater stripping tower T208. The heat source used by the reboiler of the waste water stripping tower can be fresh steam, conduction oil or material steam generated in the system.

Application example 22:

As shown in fig. 23, it is an evolution process of fig. 20, and the difference with respect to the process shown in fig. 20 is that:

The operating pressure and heat integration sequence of the four-tower three-effect heat integration shown in fig. 20 are adjusted, and the four-tower three-effect heat integration is still realized. The first rectifying tower T202 is operated at high pressure, and the second rectifying tower T203 is operated at low pressure. The gas phase at the top of the first rectifying tower T202 is used as a heating source of the tower kettle of the second rectifying tower T203 to provide the required heat for the second rectifying tower T203; the gas phase at the top of the second rectifying tower T203 is used as a heating source for tower bottoms of the light component removal tower T201 and the third rectifying tower T204, and provides required heat for the light component removal tower T201 and the third rectifying tower T204.

Application example 23:

as shown in fig. 24, it is an evolution process of fig. 20, and the difference with respect to the process shown in fig. 20 is that:

the operating pressure and heat integration sequence of the four-tower three-effect heat integration shown in fig. 20 are adjusted, and the four-tower three-effect heat integration is still realized. The first rectifying column T202 is operated at high pressure, and the third rectifying column T204 is operated at low pressure. The gas phase at the top of the first rectifying tower T202 is used as a heating source of the tower kettle of the third rectifying tower T204, and the required heat is provided for the third rectifying tower T204; the gas phase at the top of the third rectifying tower T204 is used as a heating source of tower bottoms of the light component removal tower T201 and the second rectifying tower T203, and provides required heat for the light component removal tower T201 and the second rectifying tower T203.

Application example 24:

As shown in fig. 25, it is an evolution process of fig. 2, and the difference with respect to the process shown in fig. 2 is that:

An absorption tower T205 is additionally arranged on the basis of the four-tower three-effect heat integration operation shown in fig. 2, tail gas at the top of the light component removal tower T201 is absorbed by washing water in the absorption tower T205 and then discharged out of the device, so that methanol in the tail gas is recovered, the yield of methanol products is improved, and the pollutant content in discharged noncondensable gas is reduced.

Application example 25:

As shown in fig. 26, it is an evolution process of fig. 20, and the difference with respect to the process shown in fig. 20 is that:

An absorption tower T205 is additionally arranged on the basis of the four-tower three-effect heat integration operation shown in fig. 20, tail gas at the top of the light component removal tower T201 is absorbed by washing water in the absorption tower T205 and then discharged out of the device, so that methanol in the tail gas is recovered, the yield of methanol products is improved, and the pollutant content in discharged noncondensable gas is reduced.

Application example 26:

As shown in fig. 27, it is an evolution process of fig. 26, which is different from the process shown in fig. 26 in that:

The discharged material from the tower bottom of the light component removal tower T201 shown in fig. 26 enters the first rectifying tower T202 and enters the second rectifying tower T203.

The invention provides an energy-saving process method and device for rectifying methanol, which are used for producing methanol from crude methanol by a rectification process by adopting a four-tower three-effect heat integration device. The whole device at least comprises four towers of a light component removal tower T201, a first rectifying tower T202, a second rectifying tower T203, a third rectifying tower T204 and the like and matched equipment thereof. The invention adopts a multi-tower heat integration process method, can overcome the defects of the prior art, reduces the operation energy consumption by more than 30 percent, and has obvious practicability and economic benefit. The embodiments are described in detail so that those skilled in the relevant art can make appropriate modifications, alterations and combinations of the methods according to the present invention to realize the technology. It is expressly intended that all such modifications and adaptations of the process flow provided by the present invention, as well as such modifications and adaptations, which would be apparent to those of ordinary skill in the art, are intended to be within the spirit, scope and content of the present invention.

Claims

1. A four-tower three-effect methanol rectification energy-saving process method is characterized by comprising the following steps:

1) at least comprises four towers, namely a light component removing tower (T201), a first rectifying tower (T202), a second rectifying tower (T203) and a third rectifying tower (T204);

2) The side extracted gas of the first rectifying tower (T202) enters the tower kettle of the light component removal tower (T201), the tower kettle of the light component removal tower (T201) does not need a reboiler to provide heat, and the liquid phase material of the tower kettle of the light component removal tower (T201) enters the first rectifying tower (T202); the position of the side offtake gas phase of the first rectifying tower (T202) can be near the feed inlet, or above the feed inlet, or below the feed inlet;

3) The lower part of the third rectifying tower (T204) adopts a baffle tower structure, and the baffle (S204) divides the lower part of the third rectifying tower (T204) into a methanol stripping side (L204) and an ethanol rectifying side (R204);

4) The heat integration among the first rectifying tower (T202), the second rectifying tower (T203) and the third rectifying tower (T204) is realized, and the gas phase at the top of the second rectifying tower (T203) is used as a heating source of the tower kettle of the first rectifying tower (T202) to provide the required heat for the first rectifying tower (T202); the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower kettle of the second rectifying tower (T203) to provide the second rectifying tower (T203) with required heat;

5) Enriching and then discharging noncondensable gas (9) and light components (40) from the top of the light component removal tower (T201);

6) Extracting refined methanol products from the top or upper side line of the first rectifying tower (T202), the top or upper side line of the second rectifying tower (T203) and the top or upper side line of the third rectifying tower (T204);

7) Discharging wastewater (32) from the tower kettle at the methanol stripping side (L204) of the third rectifying tower (T204);

8) A fusel oil (28) with very low content of methanol and ethanol is extracted from a side line near a feed inlet of a methanol stripping side (L204) of the third rectifying tower (T204);

9) Recovering an ethanol product (35) from the tower kettle of the ethanol rectifying side (R204) of the third rectifying tower (T204);

specifically, the method comprises the following steps: the crude methanol raw material (1) enters a light component removal tower (T201) after being preheated;

The condensate (8) of the gas phase (7) at the top of the light component removal tower (T201) condensed by the light component removal tower condenser (E201) is directly returned to the top of the light component removal tower (T201) as reflux liquid, and the noncondensable gas (9) is discharged; the side-draw gas phase (55) of the first rectifying tower (T202) enters the tower kettle of the light component removal tower (T201), the tower kettle of the light component removal tower (T201) does not need a reboiler to provide heat, and the liquid phase material (36) of the tower kettle of the light component removal tower (T201) enters the first rectifying tower (T202); the position of the side extracted gas phase of the first rectifying tower (T202) is near the feed inlet, above the feed inlet or below the feed inlet;

The condensate (11) of the gas phase (10) at the top of the first rectifying tower (T202) condensed by the condenser (E202) of the first rectifying tower is divided into two parts, one part is taken as reflux liquid (12) to directly return to the top of the first rectifying tower (T202), and the other part is taken as refined methanol product to be extracted; the upper part of the first rectifying tower (T202) or a side line extraction port is arranged and used as a refined methanol product extraction port; the tower kettle material (14) of the first rectifying tower (T202) enters a second rectifying tower (T203);

The second rectifying tower (T203) and the first rectifying tower (T202) are subjected to heat integration operation, a tower top gas phase (15) of the second rectifying tower (T203) enters a first rectifying tower reboiler (E203) shell side, a condensate (16) obtained by condensing the tower top gas phase (15) is divided into two parts, one part is taken as a reflux liquid (17) to directly return to the tower top of the second rectifying tower (T203), and the other part is taken as a refined methanol product to be extracted; the upper part of the second rectifying tower (T203) is provided with a side line extraction port as a refined methanol product extraction port; the tower kettle material (19) of the second rectifying tower (T203) enters the methanol stripping side (L204) of the third rectifying tower (T204);

The third rectifying tower (T204) and the second rectifying tower (T203) are subjected to heat integration operation, a tower top gas phase (20) of the third rectifying tower (T204) enters a shell pass of a reboiler (E204) of the second rectifying tower, a condensate (21) obtained by condensing the tower top gas phase (20) is divided into two parts, one part is taken as a reflux liquid (22) to directly return to the tower top of the third rectifying tower (T204), and the other part is taken as a refined methanol product to be extracted; the upper part of the third rectifying tower (T203) or a side line extraction port is arranged and used as a refined methanol product extraction port; the side line near the feeding port of the methanol stripping side (L204) of the third rectifying tower (T204) is used for extracting fusel oil (27) with very low methanol and ethanol content; the tower kettle material (29) at the methanol stripping side (L204) of the third rectifying tower (T204) is taken as waste water to be extracted, and the tower kettle material (34) at the ethanol rectifying side (R204) of the third rectifying tower (T204) is taken as recovered ethanol product to be extracted;

The refined methanol product (24) obtained by mixing the tower top product (13) or the tower upper side product of the first rectifying tower (T202), the tower top product (18) or the tower upper side product of the second rectifying tower (T203), the tower top product (23) or the tower upper side product of the third rectifying tower (T204) is cooled to obtain a refined methanol product (26) and sent out from the device;

The wastewater (31) obtained by cooling the wastewater (29) extracted from the tower kettle of the methanol stripping side (L204) of the third rectifying tower (T204) is divided into two streams, one stream is taken as wastewater (32) to be sent out of the device, and the other stream is taken as extract water (33) to be returned to the top of the light component removal tower (T201);

The fusel oil (27) laterally extracted from the methanol stripping side (L204) of the third rectifying tower (T204) is cooled to obtain a fusel oil product (28) which is sent out of the device;

the recovered ethanol (34) extracted from the tower kettle at the ethanol rectifying side (R204) of the third rectifying tower (T204) is cooled to obtain a recovered ethanol product (35) which is sent out of the device;

the device of the process is as follows: the device mainly comprises four towers, namely a light component removal tower (T201), a first rectifying tower (T202), a second rectifying tower (T203) and a third rectifying tower (T204), and connecting pipelines;

the raw material crude methanol feed pipeline is respectively connected with the cold side inlets of the feed methanol preheater and the feed wastewater preheater;

The cold side outlets of the feed methanol preheater and the feed wastewater preheater are connected to the middle part of the light component removal tower (T201); the top of the light component removing tower (T201) is connected with a light component removing tower condenser, a condensate outlet of the light component removing tower condenser is connected with the top of the light component removing tower (T201), and a noncondensable gas outlet of the light component removing tower condenser is connected with a noncondensable gas discharge pipeline; the bottom of the light component removing tower (T201) is connected with a first rectifying tower (T202) through a plurality of pipelines;

The top of the first rectifying tower (T202) is connected with a first rectifying tower condenser, and a condensate outlet of the first rectifying tower condenser is respectively connected with the top of the first rectifying tower (T202) and a hot side inlet of the feed methanol preheater; the side line gas phase extraction outlet of the first rectifying tower (T202) is connected with the tower kettle of the light component removal tower (T201); the bottom of the first rectifying tower (T202) is respectively connected with a first rectifying tower reboiler tube pass inlet and a second rectifying tower (T203), and a first rectifying tower reboiler tube pass outlet is connected to a first rectifying tower (T202) tower kettle;

The top of the second rectifying tower (T203) is connected with the reboiler shell side of the first rectifying tower, and the condensate outlet of the reboiler shell side of the first rectifying tower is respectively connected with the top of the second rectifying tower (T203) and the hot side inlet of the feed methanol preheater; the bottom of the second rectifying tower (T203) is respectively connected with a tube pass inlet of a reboiler of the second rectifying tower and a third rectifying tower (T204), and a tube pass outlet of the reboiler of the second rectifying tower is connected to a tower kettle of the second rectifying tower (T203);

The top of the third rectifying tower (T204) is connected with the reboiler shell side of the second rectifying tower, and the condensate outlet of the reboiler shell side of the second rectifying tower is respectively connected with the top of the third rectifying tower (T204) and the hot side inlet of the feed methanol preheater; the bottom of the methanol stripping side (L204) of the third rectifying tower (T204) is respectively connected with a tube side inlet of a reboiler of the methanol stripping side of the third rectifying tower and a hot side inlet of a feed wastewater preheater, and a tube side outlet of the reboiler of the methanol stripping side of the third rectifying tower is connected to a tower kettle of the methanol stripping side (L204) of the third rectifying tower (T204); a side line extraction pipeline near the feeding of the methanol stripping side (L204) of the third rectifying tower (T204) is connected with a hot side inlet of the fusel oil cooler; the bottom of the ethanol rectifying side (R204) of the third rectifying tower (T204) is respectively connected with a tube side inlet of an ethanol rectifying side reboiler of the third rectifying tower and a hot side inlet of an ethanol cooler, and a tube side outlet of the ethanol rectifying side reboiler of the third rectifying tower is connected to a tower kettle of the ethanol rectifying side (R204) of the third rectifying tower (T204);

the hot side outlet of the feed methanol preheater is connected with the hot side inlet of the methanol product cooler, and the hot side outlet of the methanol product cooler is connected with a methanol product extraction pipeline;

The hot side outlet of the feeding wastewater preheater is connected with the hot side inlet of the wastewater cooler, and the hot side outlet of the wastewater cooler is respectively connected with the top of the light component removal tower (T201) and the wastewater discharge pipeline; the hot side outlet of the fusel oil cooler is connected with a fusel oil product extraction pipeline; the hot side outlet of the ethanol cooler is connected with an ethanol product extraction pipeline;

the operating conditions of each column were:

The tower top operation pressure of the light component removing tower (T201) is 80-150 kpa, the tower top operation temperature is 50-85 ℃, and the tower bottom operation temperature is 55-90 ℃;

the operation pressure of the top of the first rectifying tower (T202) is 80-180 kpa, the operation temperature of the top of the tower is 50-90 ℃, and the operation temperature of the bottom of the tower is 55-100 ℃;

the operating pressure at the top of the second rectifying tower (T203) is 160-500 kPa, the operating temperature at the top of the tower is 70-130 ℃, and the operating temperature at the bottom of the tower is 75-140 ℃;

The operation pressure of the top of the third rectifying tower (T204) is 400-900 kPa, the operation temperature of the top of the tower is 90-150 ℃, and the operation temperature of the tower kettle at the methanol stripping side (L204) is 135-180 ℃; the operation temperature of the tower kettle at the ethanol rectifying side (R204) is 110-160 ℃.

2. A process according to claim 1, characterized in that: the process method adopts the four-tower three-effect heat integration to produce the methanol, or is modified into other heat integration processes to produce the methanol:

The deformation process method comprises the following steps: in the four towers, the third rectifying tower (T204) does not adopt a baffle plate structure, but adopts a conventional structure, ethanol (34) is recovered by extraction at a position above a feed inlet of the third rectifying tower (T204), fusel oil (27) is extracted at a position below the feed inlet, and tower kettle materials (29) of the third rectifying tower (T204) are extracted as wastewater;

and a deformation process method II: a stripping tower (T206) is additionally arranged on the basis of the four towers, and the third rectifying tower (T204) adopts a conventional structure instead of a baffle structure; the five towers adopt three-effect heat integration, and the gas phase at the top of the second rectifying tower (T203) is used as a heating source of the tower kettle of the first rectifying tower (T202) to provide the required heat for the first rectifying tower (T202); the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower kettle of the second rectifying tower (T203) to provide the second rectifying tower (T203) with required heat;

And a deformation process method III: in the four towers and the deformation process method-the four towers and the five towers of the deformation process method 2, an intermediate heater (E220) is additionally arranged near a feed inlet of a third rectifying tower (T204), the form of the intermediate heater can be a feed preheater or an intermediate reboiler, and the heat source can be fresh steam, heat conducting oil or material steam generated in the system;

And a deformation process method is as follows: the operation pressure of the four towers is adjusted, and the four towers are still subjected to three-effect heat integration operation; the operation pressure of the first rectifying tower (T202) is unchanged, the second rectifying tower (T203) is operated at high pressure, the third rectifying tower (T204) is operated at low pressure, and the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower kettle of the first rectifying tower (T202) to provide the required heat for the first rectifying tower (T202); the gas phase at the top of the second rectifying tower (T203) is used as a heating source of the tower kettle of the third rectifying tower (T204) to provide the required heat for the third rectifying tower (T204);

And a deformation process method: the operation pressure of the four towers in the first deformation process method is adjusted, the operation pressure of the first rectifying tower (T202) is unchanged, the second rectifying tower (T203) is operated at high pressure, the third rectifying tower (T204) is operated at low pressure, and the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower kettle of the first rectifying tower (T202) to provide the required heat for the first rectifying tower (T202); the gas phase at the top of the second rectifying tower (T203) is used as a heating source of the tower kettle of the third rectifying tower (T204) to provide the required heat for the third rectifying tower (T204);

And a deformation process method is as follows: the operation pressure of the five towers in the second deformation process method is adjusted, the operation pressure of the first rectifying tower (T202) is unchanged, the second rectifying tower (T203) is operated at high pressure, the third rectifying tower (T204) and the stripping tower (T206) are operated at low pressure, and the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower bottom of the first rectifying tower (T202) to provide the required heat for the first rectifying tower (T202); the gas phase at the top of the second rectifying tower (T203) is used as a heating source of the third rectifying tower (T204) and the stripping tower (T206) to provide the required heat for the third rectifying tower (T204) and the stripping tower (T206);

And a deformation process method seven: in the fourth tower of the deformation process method IV and the fourth tower of the deformation process method V and the fifth tower of the deformation process method V, an intermediate heater (E220) is additionally arranged near a feed inlet of the third rectifying tower (T204), the intermediate heater can be a feed preheater or an intermediate reboiler, and a heat source used can be a gas phase at the top of the second rectifying tower (T203), fresh steam, heat conducting oil or material steam generated in the system;

Eighth deformation process method: a second rectifying tower (T203) is reduced on the basis of the four towers, so that three-tower double-effect heat integration operation is changed, and a gas phase at the top of the third rectifying tower (T204) is used as a heating source of a tower kettle of the first rectifying tower (T202) to provide required heat for the first rectifying tower (T202);

And a deformation process method nine: a second rectifying tower (T203) is reduced on the basis of the four towers of the first deformation process method, the three-tower double-effect heat integration operation is changed, and the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower kettle of the first rectifying tower (T202) to provide the required heat for the first rectifying tower (T202);

And a deformation process method is ten: a second rectifying tower (T203) is reduced on the basis of the five towers of the second deformation process method, the four-tower double-effect heat integration operation is changed, and the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower kettle of the first rectifying tower (T202) to provide the required heat for the first rectifying tower (T202);

Eleven deformation process methods: in the third tower of the deformation process method eight, the third tower of the deformation process method nine and the fourth tower of the deformation process method ten, an intermediate heater (E220) is additionally arranged near a feed inlet of the third rectifying tower (T204), and the form of the intermediate heater is either a feed preheater or an intermediate reboiler, and the heat source used can be fresh steam, heat conduction oil or material steam generated in the system;

twelve deformation process methods: in the four towers, a light component removing tower reboiler (E213) is additionally arranged at the tower kettle of the light component removing tower (T201), a first rectifying tower (T202) does not need to extract gas phase from a side line to enter the light component removing tower (T201), three-effect heat integration is adopted by the four towers, the gas phase at the tower top of a second rectifying tower (T203) is respectively used as heating sources of the tower kettle of the first rectifying tower (T202) and the tower kettle of the light component removing tower (T201), and required heat is respectively provided for the first rectifying tower (T202) and the light component removing tower (T201); the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower kettle of the second rectifying tower (T203) to provide the second rectifying tower (T203) with required heat;

Thirteen deformation process methods: a recovery tower (T207) is additionally arranged on the basis of the four towers, a third rectifying tower (T204) does not adopt a partition plate structure, a conventional structure is adopted, heat integration is carried out among the three towers of the first rectifying tower (T202), the second rectifying tower (T203) and the third rectifying tower (T204), and a gas phase at the top of the second rectifying tower (T203) is used as a heating source of a tower kettle of the first rectifying tower (T202) to provide required heat for the first rectifying tower (T202); the gas phase at the top of the third rectifying tower (T204) is used as a heating source of the tower kettle of the second rectifying tower (T203) to provide the second rectifying tower (T203) with required heat; the recovery tower (T207) can adopt the gas phase at the top of the second rectifying tower (T203) or the third rectifying tower (T204) as a heat source, or adopts other heat sources in the system, or adopts an external heat source;

Fourteen deformation process methods: a waste water stripping tower (T208) is additionally arranged on the basis of the four towers, tower kettle materials on the methanol stripping side (L204) of the third rectifying tower (T204) enter the top of the waste water stripping tower (T208), and when the heating steam pressure of a reboiler of the waste water stripping tower is enough, a tower top gas phase (53) of the waste water stripping tower (T208) returns to the tower kettle on the methanol stripping side (L204) of the third rectifying tower (T204); when the pressure of heating steam of the reboiler of the waste water stripping tower is insufficient, the gas phase at the top of the waste water stripping tower (T208) can return to the tower kettle of the second rectifying tower (T203) or the tower kettle of the first rectifying tower (T202), and the tower kettle of the waste water stripping tower (T208) is used for extracting waste water; the heat source used by the reboiler of the waste water stripping tower can be fresh steam, heat conducting oil or material steam generated in the system;

Fifteen deformation process methods: the operating pressure and the heat integration sequence of the four towers described in the twelfth deforming process method are adjusted, and the four towers are still subjected to three-effect heat integration; the first rectifying tower (T202) adopts high-pressure operation, the second rectifying tower (T203) adopts low-pressure operation, and the gas phase at the top of the first rectifying tower (T202) is used as a heating source of the tower kettle of the second rectifying tower (T203) to provide the second rectifying tower (T203) with required heat; the gas phase at the top of the second rectifying tower (T203) is used as a heating source of tower kettles of the light ends removing tower (T201) and the third rectifying tower (T204) to provide required heat for the light ends removing tower (T201) and the third rectifying tower (T204);

sixteen deformation process methods: the operation pressure and the heat integration sequence of the four towers in the twelfth deformation process method are adjusted, the four towers are still subjected to three-effect heat integration, the first rectifying tower (T202) is operated at high pressure, the third rectifying tower (T204) is operated at low pressure, the gas phase at the top of the first rectifying tower (T202) is used as a heating source of the tower kettle of the third rectifying tower (T204), and the required heat is provided for the third rectifying tower (T204); the gas phase at the top of the third rectifying tower (T204) is used as a heating source of tower kettles of the light ends removing tower (T201) and the second rectifying tower (T203) to provide required heat for the light ends removing tower (T201) and the second rectifying tower (T203).

3. A process according to any one of claims 1-2, characterized in that the process used is:

1) The crude methanol raw material exchanges heat with wastewater discharged from the tower kettle of the third rectifying tower (T204) and the methanol stripping side (L204) or the crude methanol raw material exchanges heat with a methanol product; or the crude methanol raw material and the top of the first rectifying tower (T202) are subjected to gas-phase heat exchange; or the crude methanol raw material exchanges heat with the gas phase at the top of the light component removing tower (T201);

2) The feeding materials of each tower of the first rectifying tower (T202), the second rectifying tower (T203), the third rectifying tower (T204) or the light component removing tower (T201) exchange heat with the heating steam condensate.

4. A process according to any one of claims 1-2, characterized in that: an absorption tower (T205) is additionally arranged on the basis of four-tower three-effect heat integration, five-tower three-effect heat integration or three-tower double-effect heat integration, and tail gas of the light removal tower (T201) is absorbed by washing water in the absorption tower (T205) and then discharged out of the device, so that methanol in the tail gas is recovered, the yield of methanol products is improved, and the pollutant content in discharged noncondensable gas is reduced.

5. A process according to any one of claims 1-2, characterized in that: the heat source used in the third rectifying tower reboilers (E205 and E206) can be live steam, conduction oil or material steam generated in the system.

6. A process according to claim 1, characterized in that: the discharge of the tower kettle of the light component removal tower (T201) firstly enters a first rectifying tower (T202), or firstly enters a second rectifying tower (T203), or firstly enters a third rectifying tower (T204).