CN105523925B - A kind of continous way removing means for heavy solvent method TDI residues - Google Patents

Abstract

The invention belongs to the technical field of chemical recovery, and relates to a residue removal device suitable for producing and preparing TDI by a heavy solvent method. A feed pump is connected with a gas-liquid separation tank to transmit the residue solution. The gas-liquid separation tank is connected with an evaporator and a circulating pump for evaporating and vaporizing the material. The circulating pump is connected with the preheater for preheating the material. The preheater passes through The nozzle is docked with the cyclone separator, and the top of the cyclone separator is connected with the condenser to condense and recover the vaporized DEIP. The bottom end of the cyclone separator is connected with a fluidized bed dryer with a transmission device for separating DEIP gas and solids Granules, the upper end of the fluidized bed dryer is connected to the condenser to facilitate the condensation and recovery of the vaporized DEIP; the device has a simple structure, convenient operation, easy control of conditions, high efficiency, low loss, and friendly application environment.

Description

A continuous removal device for heavy solvent process TDI residue

Technical field:

The invention belongs to the technical field of chemical recovery, and relates to a device for removing residues, in particular to a device for removing residues suitable for producing and preparing TDI by a heavy solvent method, which adopts a continuous operation mode and has low loss, high efficiency, etc. features.

Background technique:

Polyurethane is an important synthetic material. One of its components is toluene diisocyanate (hereinafter referred to as TDI). There are many methods for industrial production and preparation of TDI. The common ones are amine phosgenation, nitro compound carbonylation and carbonic acid. Dimethyl ester method, and in terms of the types of solvents, TDI production methods can be divided into light solvent method and heavy solvent method. In the preparation process of TDI, due to the occurrence of side reactions, some tar-like residues are generated in the system. In practice, the residue removal methods are different due to different solvents. The residue removal in the light solvent method is to remove the residue from TDI. In the heavy solvent method, the residue is removed from the solvent diethyl isophthalate (hereinafter referred to as DEIP). Because the boiling point of DEIP is higher than that of TDI, it is not easy to vaporize, resulting in the removal of the residue of the two methods. The process is also different; in the traditional process, the residue solution of the light solvent method is first flashed in the flash tank, the vaporized TDI is condensed and recovered, and the remaining material is then sent to the thin film evaporator or LIST process for residue removal, and finally separated The residue solid contains about 20% TDI; the heavy solvent method sends the residue solution into a jacketed distillation tank, and adopts the method of intermittent distillation to remove the residue, and the finally separated residue solid contains about 40% TDI DEIP. Due to the long period, complicated operation and heavy workload of the residue removal process of the heavy solvent method, the frequent switching of refrigerant and heat medium may easily lead to equipment blockage, and the solvent recovery efficiency is low, resulting in a large part of DEIP waste. Therefore, the design of the present invention A continuous residue removal device is developed, which can efficiently remove residues in heavy solvent TDI and recover DEIP, which has good economic and ecological values.

Invention content:

The purpose of the present invention is to overcome the shortcomings of the prior art and to design a continuous removal device for TDI residue in the heavy solvent process, which can not only reduce the workload and improve the solvent recovery efficiency, but also has a simple structure and is easy to operate.

In order to achieve the above object, the main structure of the continuous removal device for heavy solvent method TDI residues involved in the present invention includes a feed pump, a gas-liquid separation tank, an evaporator, a circulation pump, a preheater, a cyclone separator, a fluidized Bed dryer, condenser, nozzle and transmission device, the feed pump is connected with the gas-liquid separation tank for conveying the residue solution, the top of the gas-liquid separation tank is connected with the condenser for condensing and recovering the vaporized DEIP, gas-liquid The separation tank is connected with an evaporator and a circulating pump for evaporating and vaporizing the material. The circulating pump is connected with the preheater for preheating the material. The preheater is connected to the cyclone separator through the nozzle, and the top of the cyclone separator It is connected with the condenser to condense and recover the vaporized DEIP. The bottom end of the cyclone separator is connected with a fluidized bed dryer with a transmission device for separating DEIP gas and solid particles. The upper end of the fluidized bed dryer is connected with the condenser. Connected to facilitate condensation recovery of vaporized DEIP.

Preferably, the continuous removal method for the heavy solvent method TDI residue realized in the continuous removal device specifically includes the following steps:

(1) Residue separation: In the process of producing and preparing TDI by the heavy solvent method, the tar impurities produced by the side reaction are separated by a separate residue removal tower in the pre-order to obtain tars with a mass fraction of 2% to 10%. residue and 98% to 90% heavy solvent diethyl isophthalate (DEIP for short) residue solution;

(2) Phase I vaporization separation: In the continuous removal device, the residue solution is sent into the gas-liquid separation tank through the feed pump, and the temperature is controlled at 170°C-210°C and the pressure is 2-8kpaA to carry out the first-stage vaporization. Diethyl isophthalate (DEIP for short) is discharged from the top of the gas-liquid separation tank and then enters the condenser for condensation recovery. It is determined that the tar residue content in the remaining material after vaporization in the first stage is 20-50%. The content of diethyl formate (DEIP for short) is 50-80%;

(3) Second stage vaporization separation: pressurize the remaining material after the first stage vaporization to 5~15bar through the circulation pump, send it to the preheater to preheat to 230℃~250℃, and then spray it through the nozzle to form a particle size of 50 ~500μm mist particle material is sent to the cyclone separator, and the pressure is controlled at 2~8kpaA to carry out the second stage vaporization, and the vaporized diethyl isophthalate (DEIP for short) is discharged from the top of the cyclone separator and then enters the condenser Condensation recovery is carried out, and the unvaporized granular material settles to the bottom of the cyclone separator. The tar residue content in the granular material is determined to be 30-60%, and the content of diethyl isophthalate (DEIP for short) is 40-70%;

(4) Phase III vaporization separation: Pour the settled granular material in the cyclone separator from the bottom into a fluidized bed dryer with a transmission device, control the temperature at 250°C to 270°C, and the pressure at 2 to 8kpaA for vaporization in Phase III , the vaporized diethyl isophthalate (DEIP for short) is discharged from the upper end of the fluidized bed dryer and enters the condenser for condensation recovery, and the unvaporized remaining material is separated at the bottom of the fluidized bed dryer to obtain powdery Residue solids, the content of diethyl isophthalate (DEIP for short) in the residue solids is less than 10%.

Compared with the prior art, the present invention adopts a continuous residue removal process, which solves the problems of long working period, heavy workload and complicated operation in the traditional technology. The designed continuous removal device can greatly improve the recovery efficiency and Reduce the content of DEIP in the residue solids, and reduce the loss of DEIP at the same time; the overall device has simple structure, convenient operation, easy control of conditions, high efficiency, low loss, and friendly application environment.

Description of drawings:

Fig. 1 is a schematic diagram of the structure and principle of the continuous removal device involved in the present invention.

Fig. 2 is a schematic diagram of the principle process of the continuous removal method involved in the present invention.

Fig. 3 is a schematic flow diagram of the continuous removal method involved in the present invention.

detailed description:

The present invention will be further described below through examples and in conjunction with the accompanying drawings, but the present invention is not limited to the following embodiments.

Example 1:

The main structure of the continuous removal device applicable to heavy solvent method TDI residue involved in this embodiment includes a feed pump 1, a gas-liquid separation tank 2, an evaporator 3, a circulation pump 4, a preheater 5, a cyclone separator 6, Fluidized bed drier 7, condenser 8, nozzle 9 and transmission device 10, feed pump 1 is connected with gas-liquid separation tank 2 and is used for conveying residue solution, and the top of gas-liquid separation tank 2 is communicated with condenser 8 so that The gasified DEIP is condensed and recovered. The gas-liquid separation tank 2 is connected with an evaporator 3 and a circulation pump 4 for evaporating and vaporizing the material. The circulation pump 4 is connected with the preheater 5 for preheating the material. The heater 5 is connected to the cyclone separator 6 through the nozzle 9, the top of the cyclone separator 6 communicates with the condenser 8 so as to condense and recover the gasified DEIP, and the bottom end of the cyclone separator 6 is connected to a fluidized bed with a transmission device 10 The dryer 7 is used to separate DEIP gas and solid particles, and the upper end of the fluidized bed dryer 7 communicates with the condenser 8 so as to condense and recover the vaporized DEIP.

The feed pump 1, evaporator 3 and preheater 5 involved in this embodiment are all existing components in the art, and the gas-liquid separation tank 2 and circulation pump 4 are separators and circulation pumps of conventional structures in the prior art respectively. Pump, cyclone separator 6, fluidized bed drier 7, condenser 8, nozzle 9 and transmission device 10 all are the parts of conventional structure sold on the market; The inside of described fluidized bed drier 7 has larger gas The separation space is convenient for separating DEIP gas and solid particles, and the gas velocity is 0.1-1m/s.

Example 2:

This embodiment is implemented in the continuous removal device of Example 1, and the continuous removal method involved specifically includes the following steps:

(1) Residue separation: In the process of producing and preparing TDI by the heavy solvent method, the tar impurities produced by the side reaction are separated by a separate residue removal tower in the pre-order to obtain tars with a mass fraction of 2% to 10%. residue and 98% to 90% heavy solvent diethyl isophthalate (DEIP for short) residue solution;

(2) Stage I vaporization separation: In the continuous removal device, the residue solution is sent to the gas-liquid separation tank 2 through the feed pump 1, and the temperature is controlled at 170°C to 210°C and the pressure is 2 to 8kpaA to carry out the stage I vaporization. Vaporized diethyl isophthalate (abbreviated as DEIP) is discharged from the top of the gas-liquid separation tank 2 and enters the condenser 8 for condensation recovery. The tar residue content in the remaining material after the vaporization of the first stage is determined to be 20-50%. , the content of diethyl isophthalate (DEIP for short) is 50-80%;

(3) Stage II vaporization separation: pressurize the remaining material after vaporization in Stage I to 5-15 bar through the circulation pump 4, send it to the preheater 5 to preheat to 230°C-250°C, and then spray it through the nozzle 9 to form granules The atomized granular material with a diameter of 50-500 μm is sent to the cyclone separator 6, and the pressure is controlled at 2-8kpaA to carry out the second-stage vaporization, and the vaporized diethyl isophthalate (DEIP for short) is discharged from the top of the cyclone separator 6 Enter after condenser 8 and carry out condensing recovery, unvaporized granular material settles to cyclone separator 6 bottoms, tar residue content is 30-60% after measuring in granular material, diethyl isophthalate (being called for short DEIP) content is 40-70%;

(4) Phase III vaporization separation: Pour the settled granular material in the cyclone separator 6 from the bottom into the fluidized bed dryer 7 with a transmission device 10, and control the temperature at 250°C to 270°C and the pressure at 2 to 8kpaA. Phase III is vaporized, and the vaporized diethyl isophthalate (DEIP for short) is discharged from the upper end of the fluidized bed dryer 7 and enters the condenser 8 for condensation recovery, and the unvaporized remaining material passes through the fluidized bed dryer 7 The bottom is separated to obtain a powdery residue solid, and the content of diethyl isophthalate (DEIP for short) in the residue solid is lower than 10%.

The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto; any change or replacement that can be easily imagined by those skilled in the art within the technical scope disclosed in the present invention, All should be covered within the protection scope of the present invention.

Claims (1)

1. a kind of continous way removing means for heavy solvent method TDI residues, it is characterised in that agent structure includes feed pump, gas Liquid knockout drum, evaporator, circulating pump, preheater, cyclone separator, fluidized bed dryer, condenser, nozzle and transmission device, Feed pump is connected with knockout drum for transmitting residue solution, and the top of knockout drum is connected in order to right with condenser The heavy solvent dimethyl isophthalate of gasification carries out condensation recovery, and evaporator and circulating pump are communicated with knockout drum, uses In being evaporated vaporization to material, circulating pump connection preheater, for being preheated to material, preheater passes through nozzle and whirlwind Separator is docked, and the top of cyclone separator is connected with condenser in order to condense the dimethyl isophthalate of recovery gasification, The bottom of cyclone separator to being connected to the fluidized bed dryer of belt driver, for separate dimethyl isophthalate gas and Solid particle, the upper end of fluidized bed dryer are connected with condenser in order to be condensed to the dimethyl isophthalate of gasification Recovery；

The continous way removing means for heavy solvent method TDI residues realizes the continous way removing side of heavy solvent method TDI residues Method specifically includes following steps：

(1) residue separates：In the production of heavy solvent method prepares TDI technical process, tarry impurities it will be passed through as caused by side reaction The separation of residue removing tower that preamble is separately provided, obtain be respectively containing mass fraction 2%~10% tar residue and 98% The residue solution of~90% heavy solvent dimethyl isophthalate；

(2) I sections of vaporization separation：In continous way removing means, residue solution is sent into knockout drum by feed pump, control 170 DEG C~210 DEG C of temperature processed, 2~8kpaA of pressure carry out I section of vaporization, and the dimethyl isophthalate of vaporization is from knockout drum Top discharge after enter condenser in carry out condensation recovery, after measured I section vaporization after leftover materials in tar residue content For 20-50%, dimethyl isophthalate content is 50-80%；

(3) II sections of vaporization separation：Leftover materials after I section of vaporization are forced into 5~15bar through circulating pump, are sent into preheater 230 DEG C~250 DEG C are preheated to, then cyclonic separation is sent into after nozzle is injected into the mist particles material that particle diameter is 50~500 μm In device, 2~8kpaA of control pressure carries out II section of vaporization, and the dimethyl isophthalate of vaporization is arranged from the top of cyclone separator Enter after going out in condenser and carry out condensation recovery, unboiled granule materials are settled down to cyclone separator bottom, after measured particle Tar residue content is 30-60% in material, and dimethyl isophthalate content is 40-70%；

(4) III sections of vaporization separation：Deposited particulate matter material in cyclone separator is poured into the stream with transmission device from bottom Change in bed dryer, 250 DEG C~270 DEG C of temperature of control, 2~8kpaA of pressure carry out III section of vaporization, the M-phthalic acid two of vaporization Ethyl ester enters in condenser after the discharge of the upper end of fluidized bed dryer carries out condensation recovery, and unboiled leftover materials are through fluidisation The isolated powdered residue solid in bottom of bed dryer, dimethyl isophthalate content is low in residue solid after measured In 10%.