CN100412051C - Heat pump rectification production method and device of butyl acetate - Google Patents

Abstract

The invention discloses a heat pump rectification production method of butyl acetate, which comprises the steps of esterifying raw materials through an esterification kettle and an esterification tower, and then rectifying them through a rectification tower, and is characterized in that it also includes The mixed gas at the top and the mixed gas from the top of the rectification tower are compressed into superheated gas, which is used as a heat source to exchange heat with the raw material, the esterification kettle and the bottom reboiler. The device used in the method includes an esterification tower, an esterification Reboiler, esterification tank, rectification tower, rectification reboiler, cooler, phase separator, regulating valve, esterification tank is connected with esterification reboiler and esterification tower, rectification tower is connected with rectification weight Boiler connection, characterized by also including two sets of heat pumps. The method of the invention can save heating steam and cooling water in the production of butyl acetate, greatly improve the energy efficiency of the process, and reduce the energy consumption of butyl acetate rectification by 56.9%. This method is applicable to the production field of butyl acetate.

Description

Heat pump rectification production method and device of butyl acetate

technical field

The invention relates to a production method of butyl acetate, in particular to a heat pump rectification production method of butyl acetate.

The invention also relates to a device for use in the above-mentioned method.

Background technique

Butyl acetate is an excellent organic solvent, widely used in coatings, spices, leather, pharmaceuticals and other industries. In recent years, as acetates have gradually replaced aliphatic ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatic solvents such as benzene, toluene and xylene, the demand for butyl acetate at home and abroad has increased significantly.

The methods for preparing butyl acetate mainly include the catalytic synthesis of neodymium trioxide, the catalytic synthesis of DH catalyst, and the esterification method using sulfuric acid catalyst. At present, the traditional sulfuric acid catalyzed esterification method is commonly used in the domestic industrial production of butyl acetate. Because this method mainly uses unit operations such as reactive distillation, the energy consumption and material consumption are relatively high. In chemical production, rectification is usually a unit process with high energy consumption, and its energy consumption accounts for about 40% of the total energy consumption. Therefore, improving the commissioning efficiency of the rectification process and reducing process energy consumption are important ways to save energy in the production of butyl acetate.

As an energy-saving technology that can effectively improve the thermal efficiency of distillation, heat pump rectification has been widely used in various chemical production processes. For example, in the separation of isobutane/n-butane, propane/propylene, ethane/ethylene and other systems and ethanol production, there are a large number of examples of the successful use of heat pump technology. The results show that heat pump rectification technology can greatly reduce Energy consumption is reduced in the production process, and significant economic benefits have been achieved.

Contents of the invention

The invention overcomes the disadvantages of the prior art and provides a heat pump rectification production method of butyl acetate. The method has the advantages of simple structure, high efficiency, energy saving, safety and reliability.

Another object of the present invention is to provide a device used in the above method.

The heat pump rectification production method of butyl acetate of the present invention comprises that raw material acetic acid and butyl ester are obtained through esterification in an esterification kettle and an esterification tower, and then obtained by rectification in a rectification tower, and is characterized in that it also includes:

The mixed gas at the top of the esterification tower is compressed into a superheated gas as a heat source to exchange heat with the raw material and the esterification tank. After heat exchange, the mixed gas returns to the high position at the top of the tower by its own pressure, and after cooling, the phases are separated to obtain crude ester and Water, return part of the crude ester and water to the esterification tower, and the rest of the crude ester enters the rectification tower; and

The mixed gas at the top of the rectification tower is compressed into a superheated gas as a heat source to exchange heat with the reboiler at the bottom of the tower. After heat exchange, the condensate obtained after further cooling is partially refluxed to the rectification tower, and the rest is sent to the feed end as a raw material.

The mixed gas from the top of the esterification tower contains 60-64% by weight of butyl acetate, 8-12% by weight of butanol and 26-30% by weight of water, with a pressure of 0.103MPa and a temperature of 91-93°C. Mixed gas, after the mixed gas is compressed, its pressure is 0.309MPa and its temperature is 154°C.

The mixed gas from the top of the rectifying tower is a mixed gas containing 39% by weight of butyl acetate, 49% by weight of butanol and 12% by weight of water, with a pressure of 0.103Mpa and a temperature of 114°C. After compression, its pressure is 0.515Mpa and its temperature is 180°C.

The invention discloses a device for realizing the heat pump rectification production method of butyl acetate, comprising an esterification tower, an esterification reboiler, an esterification kettle, a rectification tower, a rectification reboiler, a cooler, a phase separation One end of the esterification reboiler is the feed end, the other end is connected to the feed end of the esterification kettle through a pipeline, and the discharge end of the esterification kettle is fed to the esterification tower through a pipeline The bottom of the esterification tower is connected to the feed end of the esterification reboiler through a pipeline, the top of the esterification tower is connected to one end of the phase separator through a pipeline, and the other end of the phase separator is connected to the rectification tower through a pipeline The feed end and the bottom end of the rectification tower are respectively connected to the inlet end of the rectification reboiler and the product tank through pipes, the outlet end of the rectification reboiler is connected to the bottom end of the rectification tower through pipes, and the top end of the rectification tower is passed through The pipe is connected to one end of the phase separator, and the other end of the phase separator is connected to the feed end of the esterification reboiler through a pipe. The valve is respectively connected with the gas inlet port of the esterification kettle and the gas inlet port of the esterification reboiler, and the gas outlet port of the esterification kettle and the gas outlet port of the esterification reboiler are connected with one end of the cooler through a pipe, and the cooler The other end is connected to the phase separator, and one end of the other set of heat pumps is connected to the top outlet of the rectification tower through a pipeline, and the other end is connected to the gas inlet of the rectification reboiler, and the gas outlet of the rectification reboiler is connected to the One end of the cooler is connected, and the other end of the cooler is connected to the phase separator.

The present invention adds two sets of compression heat pump systems on the basis of conventional rectification butyl acetate production equipment, saves the tower top condenser, and combines compressors, esterification towers, rectification towers, tower bottom reboilers, and reaction The cyclic process composed of a combination of kettle and other equipment, consumes a small amount of electric energy, takes heat from the condenser at a lower temperature, and uses it for the heat supply of the reboiler and the reactor, so as to achieve the purpose of saving energy and reducing consumption.

Compared with the prior art, the present invention has the following advantages:

(1) Compared with the conventional flow process, the present invention does not change the process and operating parameters of the original esterification tower and the rectification tower, but the present invention compresses and heats up the gas phase azeotrope at the top of the tower, after exothermic condensation at the bottom of the tower , using its own pressure to return to the phase separator at the top of the tower, through the upgrading and utilization of low-temperature heat at the top of the tower, heating steam and cooling water can be saved, and the energy efficiency of the process can be greatly improved.

(2) the method of the present invention does not need to change the technological operation parameter of former esterification tower, rectifying tower, is suitable for the energy-saving transformation of existing conventional butyl acetate production unit.

(3) The economic benefit of the present invention is remarkable, can greatly reduce the energy consumption of production process, compare with conventional technological process, the energy consumption of heat pump rectification new technological process reduces 56.9%, equipment investment cost increases 14.5%, according to annual output 25,000 In terms of production equipment per ton of butyl acetate, the operating cost can be saved by 3.54 million yuan per year.

Description of drawings

Fig. 1 is a schematic diagram of the device structure of the present invention.

Detailed ways

As shown in Figure 1, one end of the esterification reboiler 1 is the feed end, the other end is connected to the feed end of the esterification kettle 2 through a pipeline, and the discharge end of the esterification kettle 2 is fed to the esterification tower 3 through a pipeline end connection, the bottom end of the esterification tower 3 is connected with the feed end of the esterification reboiler 1 through a pipeline, the top of the esterification tower 3 is connected with one end of the phase separator 6 through a pipeline, and the other end of the phase separator 6 is passed through The pipeline is connected to the feed end of the rectification tower 7, and one end of the heat pump 4 is connected to the outlet of the esterification tower 3 through a pipeline, and the other end is respectively connected to the gas inlet end of the esterification kettle 2 and the esterification weight through two regulating valves 12 and 13. The gas inlet end of the boiler 1 is connected, the gas outlet end of the esterification kettle 2 and the gas outlet end of the esterification reboiler 1 are connected to one end of the cooler 5 through a pipeline, and the other end of the cooler 5 is connected to the phase separator 6, and the refined The bottom end of the distillation tower 7 is connected with the inlet end and the finished product tank of the rectification reboiler 8 respectively through pipelines, the outlet end of the rectification reboiler 8 is connected with the bottom end of the rectification tower 7 through pipelines, and the top of the rectification tower 7 passes through The pipeline is connected to one end of the phase separator 11, and the other end of the phase separator 11 is connected to the feed end of the esterification reboiler 8 through a pipeline, and one end of the heat pump 9 is connected to the outlet of the rectification tower 7 through a pipeline, and the other end is It is connected to the gas inlet end of the rectification reboiler 8, and the gas outlet end of the rectification reboiler 8 is connected to one end of the cooler 10 through a pipeline, and the other end of the cooler 10 is connected to a phase separator 11 to form.

Embodiment 1 adopts the device of Fig. 1, and production process is as follows: the mixed gas from the esterification tower top is made up of the butyl acetate of 60% by weight, the butanol of 12% by weight and the water of 26% by weight, and its pressure is 0.103MPa, The temperature is 91°C, the pressure of the mixed gas is 0.309MPa after compression, and the temperature is 154°C.

The mixed gas from the top of the rectifying tower is composed of 39% by weight of butyl acetate, 49% by weight of butanol and 12% by weight of water, with a pressure of 0.103Mpa and a temperature of 114°C. After the compressed gas, its pressure It is 0.515Mpa, and the temperature is 180°C.

Compared with the conventional process, 141.6 yuan of energy consumption can be saved per ton of butyl acetate produced, and the specific energy savings are shown in Table 1.

Table 1

Among them: steam is calculated at 110 yuan/t, electricity is calculated at 0.6 yuan/kWh, and water is calculated at 0.8 yuan/t.

Embodiment 2 adopts the device of Fig. 1, and production process is as follows: the mixed gas from the esterification tower top is made up of the butyl acetate of 64% by weight, the butanol of 8% by weight and the water of 30% by weight, and its pressure is 0.103MPa, The temperature is 91-93°C, the pressure of the mixed gas is 0.309MPa after compression, and the temperature is 154°C.

The mixed gas from the top of the rectifying tower is composed of 39% by weight of butyl acetate, 49% by weight of butanol and 12% by weight of water, with a pressure of 0.103Mpa and a temperature of 114°C. After the compressed gas, its pressure It is 0.515Mpa, and the temperature is 180°C.

Compared with the conventional process, two sets of heat pump systems need to be added, and at the same time, the steam boiler system, cooling water circulation system and two tower top condensers are omitted. Since the azeotrope mixture gas is used as the working fluid, the total heat transfer coefficient of the bottom reboiler is lower than that of water vapor, so the heat transfer area of the bottom reboiler should be appropriately increased, or the enhanced heat transfer technology should be adopted. Equipment investment improvement benefits of the present invention are shown in Table 2.

Table 2

For the butyl acetate plant with a total investment of 11 million yuan and an annual output of 25,000 tons, compared with the conventional process, the heat pump process increases the equipment investment by about 1.59 million yuan, accounting for 14.5% of the total equipment investment, but the heat pump rectification process can save The operating cost of energy consumption and other equipment is about 3.54 million yuan, and the simple investment recovery period of heat pump process transformation is usually less than one year.

Claims (4)

1. the heat pump distillation production method of a N-BUTYL ACETATE, comprise that raw material is through esterifying kettle, esterification column esterification after, rectifying makes through rectifying tower, it is characterized in that also comprising:

With the compressed overheated gas that becomes of the gas mixture of esterification column cat head as thermal source and raw material and esterifying kettle heat exchange, gas mixture dependence after the heat exchange self pressure returns the high position at cat head place, phase-splitting obtains thick ester and water after cooling off, the thick ester of part, water are back to esterification column, and all the other thick esters enter rectifying tower; With

The compressed overheated gas that becomes of the gas mixture of rectifying tower cat head as thermal source and tower bottom reboiler heat exchange, is obtained phlegma and is back to rectifying tower through further cooling off the rear section after the heat exchange, rest part is delivered to feed end as raw material.

2. method according to claim 1, it is characterized in that described gas mixture from the esterification column cat head is made up of the N-BUTYL ACETATE of 60～64% weight, the butanols of 8～12% weight and the water of 26～30% weight, its pressure is 91～93 ℃ of 0.103MPa, temperature, described mixed gas after compression, its pressure is 0.309MPa, and temperature is 154 ℃.

3. method according to claim 1, it is characterized in that described gas mixture from the rectifying tower cat head is made up of the N-BUTYL ACETATE of 39% weight, the butanols of 49% weight and the water of 12% weight, pressure is 114 ℃ of 0.103Mpa, temperature, described mixed gas after compression, its pressure is 0.515Mpa, and temperature is 180 ℃.

4. device of realizing the described method of one of claim 1～3, comprise esterification column, the esterification reboiler, esterifying kettle, rectifying tower, the rectifying reboiler, water cooler, phase splitter, variable valve, esterification reboiler one end is a feed end, the other end is connected with the esterifying kettle feed end by pipeline, the discharge end of esterifying kettle is connected with the esterification column feed end by pipeline, the bottom of esterification column is connected by the feed end of pipeline with the esterification reboiler, the top of esterification column is connected with an end of phase splitter by pipeline, the other end of phase splitter is by pipe connection rectifying tower feed end, the rectifying tower bottom by pipeline respectively with the entrance end of rectifying reboiler, pan tank connects, the exit end of rectifying reboiler is connected with the rectifying tower bottom by pipeline, the top of rectifying tower is connected with an end of phase splitter by pipeline, the other end of phase splitter is by the feed end of pipe connection esterification reboiler, it is characterized in that also comprising two cover heat pumps, wherein:

One end of one cover heat pump links to each other with the esterification column tower top outlet by pipeline, the other end is connected with the gas inlet end of esterifying kettle and the gas inlet end of esterification reboiler respectively by two variable valve, the gas outlet end of the gas outlet end of esterifying kettle and esterification reboiler is connected with water cooler one end by pipeline, the other end of water cooler connect phase splitter and

One end of another set of heat pump links to each other with the rectifying tower tower top outlet by pipeline, and the other end is connected with the gas inlet end of rectifying reboiler, and the gas outlet end of rectifying reboiler is connected with water cooler one end by pipeline, and the other end of water cooler connects phase splitter.

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