Neopentyl glycol series polyester polyol tail gas treatment system

Abstract

The utility model discloses a neopentyl glycol series polyester polyol tail gas treatment system relates to polyhydric alcohol tail gas treatment technical field. The utility model discloses a reaction kettle, and the one side of reaction kettle is installed with the liquid storage tank, and the top of liquid storage tank is installed with pure water makeup water pipeline, and one side is installed with cold -proof circulation pipeline, and the top of liquid storage tank is installed with positive pressure tail gas collection pipeline, and one end of positive pressure tail gas collection pipeline is installed with tail gas condenser, and the bottom of liquid storage tank is installed with the discharge pipeline, and the bottom of discharge pipeline is installed with waste liquid collection pipeline. The utility model discloses a reaction kettle one side installs liquid storage tank and tail gas condenser, and installs positive pressure tail gas collection pipeline between liquid storage tank and tail gas condenser, utilizes the high hygroscopicity of neopentyl glycol and control its temperature in liquid storage tank and tail gas condenser, realizes the dissolving recovery function of neopentyl glycol steam in its inside before tail gas emission.

Description

Technical Field

[0001] This utility model belongs to the field of polyol tail gas treatment technology, specifically relating to a neopentyl glycol series polyester polyol tail gas treatment system. Background Technology

[0002] The polyester polyol industry often uses binary, ternary, or higher-molecular-weight alcohols as one of the reaction raw materials. Among the common binary alcohols, neopentyl glycol is used in large quantities. After the dehydration and polycondensation reaction of neopentyl glycol as a reaction raw material, tail gas is generated. This tail gas mainly contains water vapor generated by the reaction and some unreacted neopentyl glycol vapor. The high-temperature tail gas needs to be cooled before being discharged. When the discharged tail gas passes through low-temperature locations such as discharge pipes, valves, and condensers, it will cool down to below the melting point and re-solidify into a solid, which will cause pipe blockage. Therefore, the waste gas after the neopentyl glycol reaction needs to be treated.

[0003] In existing technologies, the exhaust gas is typically heated by pipeline heating or by adding steam to the pipeline to prevent neopentyl glycol in the exhaust gas from cooling below its melting point and accumulating in the pipeline and clogging it. The shortcomings of this technology are as follows: First, although the heated exhaust gas no longer clogs the discharge pipe, the gaseous neopentyl glycol in the high-temperature exhaust gas will be directly discharged into the air, causing air pollution; second, the neopentyl glycol contained in the exhaust gas is directly discharged during the discharge, resulting in the waste of reaction raw materials.

[0004] There are currently no effective solutions to the problems in the relevant technologies. Utility Model Content

[0005] The purpose of this utility model is to provide a tail gas treatment system for neopentyl glycol series polyester polyols. The technical problem to be solved is as follows: When the existing tail gas treatment system for neopentyl glycol series polyester polyols is in use, neopentyl glycol will be emitted into the air, causing air pollution and waste of raw materials.

[0006] The objective of this utility model can be achieved through the following technical solutions: A neopentyl glycol series polyester polyol tail gas treatment system includes a reaction vessel, a storage tank installed on one side of the reaction vessel, a pure water supply pipeline installed at the top of the storage tank, and a cold-insulating circulation pipeline installed on one side of the storage tank. A positive pressure tail gas collection pipeline is installed at the top of the storage tank, and a tail gas condenser is installed at one end of the positive pressure tail gas collection pipeline. Both the storage tank and the tail gas condenser are used to liquefy and absorb neopentyl glycol in the tail gas. A discharge pipeline is installed at the bottom of the storage tank, and a waste liquid collection pipeline is installed at the bottom of the discharge pipeline.

[0007] As a further embodiment of this invention: an atmospheric pressure tail gas collection pipeline is installed on one side of the top of the reactor.

[0008] As a further embodiment of this utility model: a level gauge is installed on one side of the bottom of the storage tank, and the level gauge is connected to the discharge pipeline.

[0009] As a further embodiment of this utility model: a condensate inlet pipe is installed on one side of the bottom of the exhaust gas condenser, and a condensate return pipe is installed on one side of the top. A condensate waste liquid discharge pipe is installed at the bottom of the exhaust gas condenser.

[0010] As a further embodiment of this utility model: the condensate discharge pipeline is connected to the waste liquid collection pipeline.

[0011] As a further embodiment of this utility model: an exhaust gas emission pipeline is installed on one side of the top of the exhaust gas condenser.

[0012] The beneficial effects of this utility model are: 1. By connecting the tail gas generated from the neopentyl glycol reaction vessel to a storage tank equipped with a cold-insulating circulation pipeline and a pure water replenishment pipeline, and installing a positive pressure tail gas collection pipeline at the top of the storage tank, and installing a tail gas condenser with freezing point condensate at the other end of the positive pressure collection pipeline, the neopentyl glycol vapor in the tail gas will first solidify upon encountering cold in the storage tank and dissolve in the pure water therein, forming a preliminary separation. The remaining neopentyl glycol, still in vapor state, and a small amount of water vapor in the storage tank will then pass through the positive pressure tail gas collection pipeline. After being transported to the tail gas condenser by pipeline with temperature tracing, the gas is condensed into solid alcohol and liquid water respectively. Upon contact, the solid neopentyl glycol is dissolved again. The technical advantage lies in the fact that the system, based on the high hygroscopicity of neopentyl glycol and the temperature control of the environment in which the neopentyl glycol vapor is located, ensures that the neopentyl glycol vapor discharged from the reactor is solidified and dissolved in the storage tank and tail gas condenser respectively. Thus, the tail gas after secondary separation no longer contains neopentyl glycol vapor, thereby avoiding the air pollution problem caused by heating the tail gas in the reactor and discharging it in the existing technology. 2. By installing a pure water supply pipeline at the top of the reactor, a level gauge and a discharge pipeline at the bottom, and a condensate discharge pipeline at the bottom of the tail gas condenser, and a waste liquid collection pipeline between the discharge pipeline and the condensate discharge pipeline, and connecting the waste liquid collection pipeline to an external distillation device, the system allows operators to control the concentration of neopentyl glycol in the solution by detecting the concentration of the neopentyl glycol solution in the storage tank and controlling the liquid level in the storage tank. When a small amount of solution from the tail gas condenser is externally distilled through the waste liquid collection pipeline, the neopentyl glycol raw material can be recovered while maintaining the stable and continuous operation of the system, thus solving the problem of waste of raw material during tail gas emission. 3. By installing an atmospheric pressure tail gas collection pipeline on one side of the top of the reactor and a positive pressure tail gas collection pipeline simultaneously installed on the top of the storage tank, the system can discharge the tail gas from the conventional polyester polyol reaction at the reactor through the atmospheric pressure tail gas collection pipeline, and discharge the tail gas after the reaction of neopentyl glycol series polyester polyols through the positive pressure tail gas collection pipeline. This gives the system the ability to discharge tail gas from different types of polyester polyol reactions, thus broadening the applicability of the system. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0015] In the diagram: 1. Reactor; 2. Storage tank; 3. Level gauge; 4. Discharge pipeline; 5. Waste liquid collection pipeline; 6. Condensate inlet pipeline; 7. Condensate return pipeline; 8. Tail gas discharge pipeline; 9. Atmospheric pressure tail gas collection pipeline; 10. Gas filter assembly; 11. Positive pressure tail gas collection pipeline; 12. Tail gas condenser; 13. Cold insulation circulation pipeline; 14. Pure water makeup pipeline; 15. Condensate waste liquid discharge pipeline. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0017] like Figure 1 As shown, a neopentyl glycol series polyester polyol tail gas treatment system includes a reaction vessel 1, a storage tank 2 installed on one side of the reaction vessel 1, a pure water supply pipeline 14 installed at the top of the storage tank 2, and a cold-insulating circulation pipeline 13 installed on one side. A positive pressure tail gas collection pipeline 11 is installed at the top of the storage tank 2, and a tail gas condenser 12 is installed at one end of the positive pressure tail gas collection pipeline 11. The storage tank 2 and the tail gas condenser 12 are used to jointly liquefy and absorb neopentyl glycol in the tail gas. A discharge pipeline 4 is installed at the bottom of the storage tank 2, and a waste liquid collection pipeline 5 is installed at the bottom of the discharge pipeline 4. It should be noted that a gas filter group 10 is installed between the positive pressure tail gas collection pipeline 11 and the tail gas condenser 12. The gas filter group 10 is used to adsorb various impurities in the tail gas discharged from the reactor 1, and has little impact on the small amount of gaseous neopentyl glycol remaining in the positive pressure tail gas collection pipeline 11. The tail gas discharged from the reactor 1 is in a high-temperature state. After being put into the storage tank 2, it needs to be cooled down by the cold insulation circulation pipeline 13 so that it can be cooled down to the freezing point and then come into contact with the pure water in the tank. The reason for condensing it and contacting it with pure water is that neopentyl glycol itself has strong hygroscopicity. When it is in a solid state, if it comes into contact with water, it will absorb water and dissolve into a liquid state. This system realizes the dissolution and recovery of solid neopentyl glycol by putting the tail gas into the storage tank 2 containing pure water before the tail gas is discharged, in conjunction with the secondary condensation of the tail gas condenser 12.

[0018] An atmospheric pressure tail gas collection pipeline 9 is installed on one side of the top of reactor 1; It should be noted that since the freezing point of conventional polyester polyols is much lower than room temperature, the ambient temperature after cooling and discharge from reactor 1 is higher than their freezing point. Therefore, they are in a liquid state during subsequent discharge, and there is no risk of pipe blockage. However, neopentyl glycol, which contains a small amount of water, can solidify at room temperature. Therefore, a separate positive pressure tail gas collection pipeline 11 is required for transmission. Specifically, the positive pressure tail gas collection pipeline 11 is equipped with active positive pressure air supply compared to the atmospheric pressure tail gas collection pipeline 9, and it needs to provide high-temperature heating above its melting point to increase the waste gas flow rate, reduce the waste gas residence time, and prevent neopentyl glycol from remaining in the pipeline by purging deposits. The purpose is to set up two separate waste gas treatment pipelines to facilitate reactor 1 to adapt to the production requirements of various polyester polyols, facilitate tail gas treatment and improve production efficiency, and reduce the situation of positive pressure tail gas entering atmospheric pressure reactor 1.

[0019] A level gauge 3 is installed on one side of the bottom of the storage tank 2, and the level gauge 3 is connected to the discharge pipeline 4; It should be noted that when the pure water replenishment pipeline 14 injects into the storage tank 2, the neopentyl glycol in the exhaust gas from the reactor 1 exists inside the reactor 1 in the form of high-temperature vapor. It does not come into direct contact with the pure water. After the reactor 1 is cooled by the cold circulation pipeline 13, the neopentyl glycol solidifies and falls back into the pure water to dissolve. That is, the storage tank 2 absorbs and dissolves the neopentyl glycol by relying on its hygroscopic properties. Furthermore, the amount of pure water in the reactor 1 can be observed by the level gauge 3. During the actual absorption of neopentyl glycol, the staff takes samples of the solution in the storage tank 2 at fixed intervals to calculate the discharge volume and the required replenishment volume based on the neopentyl glycol concentration. The discharge concentration of the neopentyl glycol solution can be manually controlled by controlling the pure water level in the storage tank 2 and the timing of the discharge from the discharge pipeline 4, so as to reduce the burden on the subsequent treatment system to separate the neopentyl glycol and maintain the continuous and stable operation of the entire system.

[0020] When the tail gas undergoing preliminary neopentyl glycol separation in the storage tank 2 is transported to the tail gas condenser 12 via the positive pressure tail gas collection pipeline 11, a small amount of pure water vapor from the storage tank 2 and neopentyl glycol vapor from the reaction vessel 1 still remain. To remove this residue from the tail gas, the tail gas is transported under high pressure with heat tracing through the positive pressure tail gas collection pipeline 11. During this stage, both the water vapor and neopentyl glycol are in vapor state and are blown away at high speed to the tail gas condenser 12, and will not accumulate in the positive pressure tail gas collection pipeline 11.

[0021] A condenser water inlet pipe 6 is installed on one side of the bottom of the exhaust gas condenser 12, and a condenser water return pipe 7 is installed on one side of the top. A condenser waste liquid discharge pipe 15 is installed at the bottom of the exhaust gas condenser 12. It should be noted that the condensate water input to the exhaust gas condenser 12 via the condensate inlet pipe 6 is freezing point cold water. Therefore, the water vapor and neopentyl glycol in the exhaust gas are condensed into liquid water and solid alcohol, respectively. Due to the strong hygroscopicity of neopentyl glycol, it dissolves upon contact with the condensate water. The dissolved neopentyl glycol solution is discharged through the condensate waste liquid discharge pipe 15.

[0022] The condensate discharge pipeline 15 is connected to the waste liquid collection pipeline 5, and the waste liquid collection pipeline 5 is connected to a distillation column (not shown). It should be noted that since the neopentyl glycol solution processed in the tail gas condenser 12 is a small amount of untreated residue, after condensation and collection, it is connected by the condensate waste liquid discharge pipeline 15, which is a branch pipeline, to the waste liquid collection pipeline 5 of the solution transport main pipeline. This part of the waste liquid is then transferred to the distillation column for fraction recovery, thereby avoiding the loss of raw materials when the tail gas is discharged after the reaction of the reactor 1 is completed, and improving the utilization rate of raw materials.

[0023] An exhaust gas discharge line 8 is installed on one side of the top of the exhaust gas condenser 12. As can be seen from the above, the neopentyl glycol vapor in the exhaust gas discharged by the exhaust gas discharge line 8 is initially separated by the liquid storage tank 2 and then separated again at the exhaust gas condenser 12, thus achieving effective separation of neopentyl glycol in the exhaust gas. Therefore, the exhaust gas discharge line 8 no longer has the effect of polluting the air after discharging the cleaned exhaust gas.

[0024] The above description provides a detailed account of one embodiment of the present invention. However, this description is merely a preferred embodiment and should not be construed as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the claims of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A tail gas treatment system for neopentyl glycol series polyester polyols, comprising a reaction vessel (1), characterized in that, A liquid storage tank (2) is installed on one side of the reactor (1). A pure water supply pipeline (14) is installed at the top of the liquid storage tank (2), and a cold insulation circulation pipeline (13) is installed on one side. A positive pressure tail gas collection pipeline (11) is installed at the top of the liquid storage tank (2). A tail gas condenser (12) is installed at one end of the positive pressure tail gas collection pipeline (11). Both the liquid storage tank (2) and the tail gas condenser (12) are used to liquefy and absorb neopentyl glycol in the tail gas. A discharge pipeline (4) is installed at the bottom of the liquid storage tank (2), and a waste liquid collection pipeline (5) is installed at the bottom of the discharge pipeline (4).

2. The neopentyl glycol series polyester polyol tail gas treatment system according to claim 1, characterized in that, An atmospheric pressure tail gas collection pipeline (9) is installed on one side of the top of the reactor (1).

3. The neopentyl glycol series polyester polyol tail gas treatment system according to claim 1, characterized in that, A level gauge (3) is installed on one side of the bottom of the storage tank (2), and the level gauge (3) is connected to the discharge pipeline (4).

4. The neopentyl glycol series polyester polyol tail gas treatment system according to claim 1, characterized in that, The tail gas condenser (12) has a condensate inlet pipe (6) installed on one side of the bottom and a condensate return pipe (7) installed on one side of the top. The tail gas condenser (12) also has a condensate waste liquid discharge pipe (15) installed at the bottom.

5. The neopentyl glycol series polyester polyol tail gas treatment system according to claim 4, characterized in that, The condensate discharge pipeline (15) is connected to the waste liquid collection pipeline (5).

6. The neopentyl glycol series polyester polyol tail gas treatment system according to claim 1, characterized in that, The exhaust gas condenser (12) has an exhaust gas discharge pipeline (8) installed on one side of its top.

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