Energy-saving device for rectifying propylene carbonate

Abstract

The utility model discloses an energy-saving device for rectifying propylene carbonate. Comprising a film evaporator (E-1001), a demister (V-1001), a demister top pressure (P3), a demister top temperature (T3), a residual liquid pump (P-1001), a steam inlet valve group (1), a rectifying tower (T-1001), a tower top temperature (T1), a tower top pressure (P1), a tower kettle pressure (P2), a tower kettle temperature (T2), a tower kettle liquid level (L1), a primary condenser (E-1003), a secondary condenser (E-1004), a rectifying tower reflux tank (V-1002), a rectifying tower reflux pump (P-1003) and a rectifying tower product tank (V-1003). The device comprises a rectifying tower, a rectifying tower product pump (P-1004), a rectifying tower reboiler (E-1002), a rectifying tower kettle pump (P-1002) and the like. According to the energy-saving device for rectifying propylene carbonate, battery-grade propylene carbonate can be continuously and efficiently rectified, and compared with the traditional process, the use amount of steam and cooling water can be greatly saved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the production technology field of rectifying propylene carbonate in the propylene carbonate production process of pressurization method, especially to a kind of energy-saving method for rectifying propylene carbonate. BACKGROUND

[0002] Propylene carbonate (PC) is a kind of chemical substance, colorless or slightly yellow transparent liquid, non-toxic, non-corrosive, slightly aromatic at room temperature, easily soluble in acetone, chloroform, benzene, ether, ethyl acetate, water and carbon tetrachloride. Propylene carbonate has excellent performance, with high dielectric constant, high thermal stability, low viscosity, low volatility and other characteristics. Propylene carbonate can be used as oil solvent, spinning solvent, olefin and aromatic extraction agent, etc.; it has strong absorption capacity for carbon dioxide and hydrogen sulfide and other gases, which can be used in natural gas purification, ammonia raw material gas purification and other fields; in the battery industry, especially in lithium ion battery, propylene carbonate is used as electrolyte component to protect graphite anode; in polymer industry, it is used as polymer solvent and plasticizer. It can also be used as synthetic fiber aid and fixing agent, wood adhesive, etc.

[0003] Propylene carbonate preparation process includes phosgene method, ester exchange method, propylene oxide and carbon dioxide pressurization method, etc., at present, propylene oxide and carbon dioxide pressurization method is the mainstream preparation method in industrial field at present stage, in the process of producing propylene carbonate by pressurization method, crude propylene carbonate needs to be purified into battery-grade propylene carbonate product through distillation, rectification and other processes, the traditional way is that crude propylene carbonate passes through membrane evaporator, gas phase comes out from the top, and then changes into liquid phase through condenser, and is transported to rectification column for rectification. This traditional distillation and rectification process, crude propylene carbonate is evaporated from the top of membrane evaporator in gas phase, and then condensed into liquid, and then transported to rectification column to be heated into gas phase to participate in gas-liquid exchange. This process needs to be heated twice and condensed once, which needs a large amount of steam and cooling water. The utility model proposes an energy-saving device for this situation, which directly introduces the gas phase material from the top of membrane evaporator into rectification column, avoiding the process of repeatedly heating the gas phase material from the top of membrane evaporator into gas phase after condensation, which greatly saves the amount of steam and cooling water. SUMMARY

[0004] The technical problem solved by the utility model lies in providing an energy-saving device for rectifying propylene carbonate, which can effectively rectify crude propylene carbonate into battery-grade propylene carbonate product, and in the rectification process, the light component material of the crude propylene carbonate is evaporated from the top in the form of gas phase through a thin film evaporator, and the gas phase material directly enters a rectification tower for rectification after passing through a defoamer. In view of this, the energy-saving device for rectifying propylene carbonate comprises a thin film evaporator (E-1001), a defoamer (V-1001), defoamer top pressure (P3), defoamer top temperature (T3), a residual liquid pump (P-1001), a steam inlet valve group (1), a rectification tower (T-1001), tower top temperature (T1), tower top pressure (P1), tower kettle pressure (P2), tower kettle temperature (T2), tower kettle liquid level (L1), a first-stage condenser (E-1003), a second-stage condenser (E-1004), a rectification tower reflux tank (V-1002), a rectification tower reflux pump (P-1003), a rectification tower product tank (V-1003), a rectification tower product pump (P-1004), a rectification tower reboiler (E-1002) and a rectification tower kettle pump (P-1002).

[0005] The crude propylene carbonate ester is connected to the feed end of the thin film evaporator (E-1001), the bottom liquid phase discharge end of the thin film evaporator (E-1001) is connected to the residual liquid pump (P-1001), the top gas phase discharge end of the thin film evaporator (E-1001) is connected to the feed end of the defoaming device (V-1001), the discharge end of the defoaming device (V-1001) is connected to the feed end of the rectification tower (T-1001), the tower kettle discharge of the rectification tower (T-1001) is connected to the rectification tower kettle pump (P-1002), the discharge liquid of the rectification tower kettle pump (P-1002) is connected to the feed inlet of the rectification tower reboiler (E-1002), and the material is circulated after passing through the rectification tower reboiler and entering the rectification tower (T-1001), one of the discharges is connected to the heavy component recovery system, the top gas phase discharge end of the rectification tower (T-1001) is connected to the feed end of the tower top primary condenser (E-1003), the liquid phase discharge end of the tower top primary condenser (E-1003) is connected to the feed end of the rectification tower reflux tank (V-1002), the gas phase discharge end of the tower top primary condenser (E-1003) which is not condensed is connected to the feed end of the tower top secondary condenser (E-1004), the gas phase discharge end of the tower top secondary condenser (E-1004) is connected to the vacuum system, the liquid phase discharge end of the tower top secondary condenser (E-1004) is connected to the feed end of the rectification tower reflux tank (V-1002), the discharge end of the rectification tower reflux tank (V-1002) is connected to the light component recovery system through the rectification tower reflux pump (P-1003), and one of the discharges is connected to the rectification tower (T-1001) as reflux liquid; the battery grade propylene carbonate is taken out from the side line of the rectification tower (T-1001), and the taken product is connected to the inlet of the rectification tower product pump (P-1004) through the rectification tower product tank (V-1003).

[0006] The top temperature (T3) of the defoaming device is remotely DCS automatically interlocked controlled with the steam inlet valve group (1) of the thin film evaporator, the opening degree of the steam inlet valve group (1) of the thin film evaporator controls the gas phase outlet temperature of the top of the defoaming device to be between 115-130 ℃, when the gas phase outlet temperature is lower than 115 ℃, the opening degree of the steam inlet valve group (1) can be increased to increase the steam delivery amount, so that the temperature of the gas phase outlet is increased, and the gas phase material can better exchange with the liquid in the rectification tower to ensure the rectification effect of the rectification tower; on the contrary, when the gas phase outlet temperature of the top of the defoaming device is higher than 130 ℃, the opening degree of the steam inlet valve group can be reduced to reduce the steam delivery amount, so as to prevent the temperature from being too high, reduce the rectification effect and increase the side reaction, and the product quality cannot meet the requirements.

[0007] The energy-saving device for rectifying propylene carbonate adopts negative pressure operation, a vacuum pump is used to vacuumize the secondary condenser (E-1004), so that the whole operation system of the energy-saving device for rectifying propylene carbonate is under negative pressure. Since the boiling point of propylene carbonate is relatively high and propylene carbonate is a heat-sensitive material, rectification under normal pressure will waste a large amount of heat and cause decomposition of propylene carbonate, increase of side reactions, low product yield, therefore, the device adopts negative pressure rectification operation, the vacuum degree of the energy-saving device for rectifying propylene carbonate is controlled to be-0.080MPa-0.097MPa (gauge pressure), so that the whole device can achieve negative pressure rectification, heat is saved, and product quality and yield are improved.

[0008] The utility model has the advantages of:

[0009] (1) The light component material is evaporated from the top in the form of gas by the thin film evaporator, and then directly enters the rectifying tower for rectification after the defoaming device. This process can save the condensation and vaporization process of the material, greatly saving the steam and cooling water consumption.

[0010] (2) The energy-saving device for rectifying propylene carbonate adopts DCS automatic control, simplifying the production operation.

[0011] (3) The negative pressure operation effectively avoids the decomposition of propylene carbonate and other side reactions. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The device schematic diagram of the utility model. DETAILED DESCRIPTION

[0013] The utility model is further described in combination with examples, and the following examples are intended to illustrate the utility model, rather than limit the utility model.

[0014] In view of the existing equipment for rectifying propylene carbonate in the production process of preparing propylene carbonate by the pressurization method, the utility model provides an energy-saving device for rectifying propylene carbonate, which comprises a thin film evaporator (E-1001), a defoaming device (V-1001), a defoaming device top pressure (P3), a defoaming device top temperature (T3), a residual liquid pump (P-1001), a steam inlet valve group (1), a rectifying tower (T-1001), a tower top temperature (T1), a tower top pressure (P1), a tower kettle pressure (P2), a tower kettle temperature (T2), a tower kettle liquid level (L1), a primary condenser (E-1003), a secondary condenser (E-1004), a rectifying tower reflux tank (V-1002), a rectifying tower reflux pump (P-1003), a rectifying tower product tank (V-1003), a rectifying tower product pump (P-1004), a rectifying tower reboiler (E-1002), and a rectifying tower kettle pump (P-1002).

[0015] The crude propylene carbonate is connected to the feed end of the thin film evaporator (E-1001), the bottom liquid phase outlet of the thin film evaporator (E-1001) is connected to the residual liquid pump (P-1001), the top gas phase outlet of the thin film evaporator (E-1001) is connected to the feed end of the defoamer (V-1001), the outlet end of the defoamer (V-1001) is connected to the feed end of the rectifying tower (T-1001), the tower kettle outlet of the rectifying tower (T-1001) is connected to the rectifying tower kettle pump (P-1002), the outlet liquid of the rectifying tower kettle pump (P-1002) is connected to the feed inlet of the rectifying tower reboiler (E-1002), and the outlet liquid is fed into the rectifying tower (T-1001) through the rectifying tower reboiler, so as to achieve the circulation of the material, one outlet is connected to the heavy component recovery system, the top gas phase outlet of the rectifying tower (T-1001) is connected to the feed end of the tower top primary condenser (E-1003), the liquid phase outlet of the tower top primary condenser (E-1003) is connected to the feed end of the rectifying tower reflux tank (V-1002), the gas phase outlet of the tower top primary condenser (E-1003) which is not condensed is connected to the feed end of the tower top secondary condenser (E-1004), the gas phase outlet of the tower top secondary condenser (E-1004) is connected to the vacuum system, the liquid phase outlet of the tower top secondary condenser (E-1004) is connected to the feed end of the rectifying tower reflux tank (V-1002), the outlet end of the rectifying tower reflux tank (V-1002) is connected to the light component recovery system through the rectifying tower reflux pump (P-1003), and one outlet is connected to the rectifying tower (T-1001) as reflux liquid, the battery grade propylene carbonate is collected from the side line of the rectifying tower (T-1001), and the collected product is connected to the inlet of the rectifying tower product pump (P-1004) through the rectifying tower product tank (V-1003).

[0016] The device adds crude propylene carbonate ester into a thin film evaporator (E-1001), heats the thin film evaporator (E-1001) by using steam as a heat source, controls the opening degree of a vapor inlet valve group (1) of the thin film evaporator to control the temperature of a gas phase outlet at the top of a defoamer at 115-130℃, ensures that the gas phase material entering the rectifying tower can better participate in the gas-liquid separation of the material in the rectifying tower, and achieves better rectification effect, the gas phase material at the top of the thin film evaporator (E-1001) enters the rectifying tower (T-1001) after passing through the defoamer, and the rectifying tower (T-1001) is heated by a rectifying tower reboiler (E-1002). The rectifying tower (T-1001) adopts negative pressure rectification, a secondary condenser (E-1004) is used to extract vacuum, the vacuum degree of the propylene carbonate energy-saving device is controlled at-0.08MPa-0.097MPa (gauge pressure), so that the entire propylene carbonate energy-saving device can achieve negative pressure rectification. The gas phase material at the top of the rectifying tower enters a primary condenser (E-1003), and propylene oxide, carbon dioxide and a small amount of propylene carbonate are rectified out, the liquid phase condensed down enters a rectifying tower reflux tank (V-1002), and the gas phase not condensed down enters a secondary condenser (E-1004) at the top of the tower for further condensation and recovery, the liquid phase out of the secondary condenser (E-1004) at the top of the tower also enters the rectifying tower reflux tank (V-1002), part of the liquid phase in the reflux tank is refluxed, and part is extracted to a light component recovery system for recovery treatment, so as to avoid waste of raw materials. The rectifying tower (T-1001) is connected with a rectifying tower bottom pump (P-1002), the rectifying tower bottom pump (P-1002) extracts the material liquid, one of which is connected with the inlet of the rectifying tower reboiler (E-1002), enters the rectifying tower (T-1001) after passing through the rectifying tower reboiler, and the other is extracted to a heavy component recovery system for recovery. The side extraction temperature of the rectifying tower is controlled, when the temperature reaches, the content of the product extracted by the side line is analyzed, after the content of propylene carbonate is greater than 99.99%, the propylene carbonate is self-flowed to a rectifying tower product tank (V-1003) by gravity. The battery-grade propylene carbonate refined by the energy-saving device can meet the national standard.

[0017] For a rectification device with an annual output of 60,000 tons of battery-grade propylene carbonate, the test results are as follows: the above-mentioned embodiment is only one implementation form of the energy-saving device for rectifying propylene carbonate according to the present application, according to other deformations of the scheme provided by the present application, increasing or reducing the components or steps therein, or applying the present application to a similar technical field as the present application, all belong to the protection scope of the present application.

Claims

1. An energy-saving apparatus for rectifying propylene carbonate, characterized by comprising: The system comprises: a thin film evaporator (E-1001), a demister (V-1001), a demister top pressure (P3), a demister top temperature (T3), a residual liquid pump (P-1001), a steam inlet valve group (1), a rectifying tower (T-1001), a tower top temperature (T1), a tower top pressure (P1), a tower bottom pressure (P2), a tower bottom temperature (T2), a tower bottom liquid level (L1), a first-stage condenser (E-1003), a second-stage condenser (E-1004), a rectifying tower reflux tank (V-1002), a rectifying tower reflux pump (P-1003), a rectifying tower product tank (V-1003), a rectifying tower product pump (P-1004), a rectifying tower reboiler (E-1002), and a rectifying tower bottom pump (P-1002); wherein the crude propylene carbonate is connected to the feed end of the thin film evaporator (E-1001), the bottom liquid phase outlet end of the thin film evaporator (E-1001) is connected to the residual liquid pump (P-1001), the top gas phase outlet end of the thin film evaporator (E-1001) is connected to the feed end of the demister (V-1001), the outlet end of the demister (V-1001) is connected to the feed end of the rectifying tower (T-1001), the tower bottom outlet of the rectifying tower (T-1001) is connected to the rectifying tower bottom pump (P-1002), the outlet of the rectifying tower bottom pump (P-1002) is connected to the feed inlet of the rectifying tower reboiler (E-1002), and the outlet after the rectifying tower reboiler enters the rectifying tower (T-1001) to achieve material circulation, one outlet is connected to a heavy component recovery system, the gas phase outlet end of the rectifying tower (T-1001) is connected to the feed end of the first-stage condenser (E-1003) at the tower top, the liquid phase outlet end of the first-stage condenser (E-1003) is connected to the feed end of the rectifying tower reflux tank (V-1002), the gas phase outlet end of the first-stage condenser (E-1003) that is not condensed is connected to the feed end of the second-stage condenser (E-1004) at the tower top, the gas phase outlet end of the second-stage condenser (E-1004) is connected to a vacuum system, the liquid phase outlet end of the second-stage condenser (E-1004) is connected to the feed end of the rectifying tower reflux tank (V-1002), and the outlet end of the rectifying tower reflux tank (V-1002) is connected to the rectifying tower reflux pump (P-1003), one outlet is connected to a light component recovery system, and one outlet returns to the rectifying tower (T-1001) as reflux liquid; the rectifying tower (T-1001) side line extracts battery-grade propylene carbonate, and the extracted product is connected to the inlet of the rectifying tower product pump (P-1004) through the rectifying tower product tank (V-1003).

2. The energy saving apparatus for rectifying propylene carbonate according to claim 1, wherein The crude propylene carbonate is distilled by using a thin film evaporator, and light component materials directly enter a rectifying tower in a gas phase form for rectification.

3. The energy saving apparatus for rectifying propylene carbonate according to claim 1, wherein The demister top temperature (T3) and the steam inlet valve group (1) of the thin film evaporator are set to remote DCS automatic interlocking control, and the opening degree of the steam inlet valve group (1) of the thin film evaporator controls the temperature of the demister top gas phase outlet temperature meter.

4. The energy saving apparatus for rectifying propylene carbonate according to claim 1, wherein The rectification column (T-1001) is operated under a negative pressure, and a vacuum pump is used to vacuumize the secondary condenser (E-1004), so that the operation system of the rectification column (T-1001) and the operation system of the thin film evaporator (E-1001) are under a negative pressure.

Images