Rectification device for producing polyester-grade ethylene glycol

Abstract

The utility model belongs to the field of fine chemical raw material preparation, and particularly relates to a rectification device for producing polyester-grade ethylene glycol, which comprises a crude ethylene glycol pipeline, a preheating tank, a light component removal tower and an ethylene glycol product tower which are connected in sequence, the crude ethylene glycol pipeline is connected to the top of the preheating tank, and the bottom of the preheating tank is provided with a stabilizer inlet, a nitrogen inlet and a discharge port; the other end of the discharge hole is connected to the middle part of the light component removal tower; the stabilizer inlet is connected with a metering pump; and the top of the preheating tank is also connected with a condenser. The preheating tank is arranged in front of the light component removal tower, a stabilizer and crude ethylene glycol are preheated at the same time, nitrogen is introduced into the bottom of the tank for blowing, materials are fully mixed, oxygen dissolved in the raw materials is blown off, acidic substances and aldehyde substances are prevented from being generated in the rectification process, and therefore the UV value of an ethylene glycol product is increased.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of fine chemical raw material preparation, concretely is a kind of rectifying device for producing polyester grade ethylene glycol. BACKGROUND

[0002] Ethylene glycol is a very important chemical product, widely used, can be used as antifreeze and polyester fiber raw material, wherein polyester fiber industry demand accounts for more than 40% of total consumption, and as the main raw material of polyester fiber ethylene glycol has a special ultra-violet light transmittance index (Ultra-Violet Light Transmittance, hereinafter referred to as UV value), that is, when the liquid layer thickness is 1cm, the UV transmittance of ethylene glycol is measured at 220nm, 275mm, 350nm respectively.

[0003] At present, in the process device of the ester exchange method device for preparing ethylene glycol, there may be trace impurities such as aldehyde, ketone, acid (mainly impurities containing carbonyl, conjugated double bond) in the produced ethylene glycol finished product, which affects the UV value, in the existing conventional ethylene glycol refining process, the trace impurities cannot be removed, and the unqualified UV value will affect the quality of the fiber and the application range of the product, thereby reducing the economic benefit of the production device. Therefore, how to remove the impurities in crude ethylene glycol simply and efficiently, improve the ultraviolet transmittance of ethylene glycol, so that it can meet the polyester grade ethylene glycol standard, is crucial for the use of ethylene glycol as polyester fiber raw material.

[0004] At present, physical method and chemical method are usually used to remove impurities in ethylene glycol, wherein physical method mainly includes adsorption and membrane separation method, and chemical method is mainly catalytic hydrogenation method. Physical method has the defects of limited adsorption amount, cannot be reused, complicated production device process, high cost and the like;Catalytic hydrogenation method has the defects of unstable fixed bed catalyst carrier in liquid phase, large energy consumption, many secondary by-products, corrosion to equipment packing and the like, and cannot be widely used in industrial production device. In view of this, it is necessary to design an economical, simple and efficient device for refining crude ethylene glycol. UTILITY MODEL CONTENTS

[0005] To solve the problems in the above background art, the utility model provides a rectifying device for producing polyester grade ethylene glycol, which is provided with a preheating tank in front of the light removal tower, the stabilizer and crude ethylene glycol are preheated at the same time, nitrogen is introduced into the tank bottom to blow, the materials are fully mixed, and the oxygen dissolved in the raw materials is blown off, so as to avoid the generation of acidic substances and aldehyde substances in the rectification process, thereby improving the UV value of ethylene glycol product.

[0006] The utility model adopts the following technical solutions:

[0007] The application relates to a rectification device for producing polyester-grade ethylene glycol, which comprises a crude ethylene glycol pipeline, a preheating tank, a light-removing tower and an ethylene glycol product tower connected in sequence, wherein:

[0008] The crude ethylene glycol pipeline is connected to the top of the preheating tank, the bottom of the preheating tank is provided with a stabilizer inlet, a nitrogen inlet and a discharge port, the discharge port is connected to the middle part of the light-removing tower at the other end, a metering pump is connected to the stabilizer inlet, and a condenser is further connected to the top of the preheating tank.

[0009] Further, the nitrogen inlet at the bottom of the preheating tank is provided with a plurality of nitrogen inlets connected to a nitrogen tank.

[0010] Further, the top of the light-removing tower is connected with a first cooler, the first cooler has two outlets, one of which is connected to a vacuum system, and the other is connected to the top of the light-removing tower through a first reflux pump.

[0011] Further, the bottom of the light-removing tower is connected to the middle part of the ethylene glycol product tower through a kettle liquid conveying pump.

[0012] Further, the top of the ethylene glycol product tower is connected with a second cooler, the second cooler has two outlets, one of which is connected to a vacuum system, and the other is connected to the top of the ethylene glycol product tower through a second reflux pump.

[0013] Further, the top of the ethylene glycol product tower is connected to a crude ethylene glycol removing tank through a first conveying pipeline; the upper part of the ethylene glycol product tower is connected to a polyester-grade ethylene glycol product tank through a second conveying pipeline; and the bottom of the ethylene glycol product tower is connected to a waste alcohol removing tank through a third conveying pipeline.

[0014] Further, the first conveying pipeline is provided with a first valve, the second conveying pipeline is provided with a second valve, and the third conveying pipeline is provided with a third valve.

[0015] Compared with the prior art, the rectification device has the advantages that:

[0016] The rectification device comprises a preheating tank, a crude ethylene glycol pipeline and a condenser are connected to the top of the preheating tank, the bottom of the preheating tank is provided with a stabilizer inlet, a nitrogen inlet and a discharge port, and the crude ethylene glycol and the stabilizer are simultaneously preheated by feeding materials into the preheating tank through the crude ethylene glycol pipeline and the stabilizer inlet during use; nitrogen is intermittently supplemented through the nitrogen inlet during the preheating process, the materials are fully mixed, and the dissolved oxygen in the materials is blown off at the same time, so that acidic substances and aldehyde substances are avoided to be generated during the rectification process, and thus the UV value of the ethylene glycol product is improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of a distillation apparatus provided in an embodiment of this application;

[0019] The components are: 1-Crude ethylene glycol pipeline, 2-Preheating tank, 3-Light ethylene glycol removal tower, 4-Ethylene glycol product tower, 5-Stabilizer inlet, 6-Nitrogen inlet, 7-Discharge port, 8-Metering pump, 9-Condenser, 10-First cooler, 11-First reflux pump, 12-Vacuum system, 13-Bottle liquid transfer pump, 14-Second cooler, 15-Second reflux pump, 16-First transfer pipeline, 17-Crude ethylene glycol tank, 18-Second transfer pipeline, 19-Polyester grade ethylene glycol finished product tank, 20-Third transfer pipeline, 21-Waste alcohol tank. Detailed Implementation

[0020] The technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0021] The following is in conjunction with the appendix Figure 1 The present invention will be described in detail with specific embodiments.

[0022] like Figure 1 As shown, this utility model provides a distillation apparatus for producing polyester-grade ethylene glycol, comprising a crude ethylene glycol pipeline 1, a preheating tank 2, a light-light gas removal tower 3, and an ethylene glycol product tower 4 connected in sequence. The crude ethylene glycol pipeline 1 is connected to the top of the preheating tank 2. The bottom of the preheating tank 2 is equipped with a stabilizer inlet 5, a nitrogen inlet 6, and a discharge port 7, which is connected to the middle of the light-light gas removal tower 3. A metering pump 8 is connected to the stabilizer inlet 5. A condenser 9 is also connected to the top of the preheating tank 2, from which a small amount of non-condensable gas is discharged. This application improves the UV value of the ethylene glycol product by setting up a preheating tank 2 before the light-light gas removal tower 3, simultaneously preheating the stabilizer and crude ethylene glycol, and intermittently blowing nitrogen gas through the bottom of the tank to fully mix the materials and remove dissolved oxygen from the raw materials. This avoids the generation of acidic substances and aldehydes during distillation.

[0023] In some embodiments, the nitrogen inlet 6 at the bottom of the preheating tank 2 is provided with multiple inlets, which are evenly distributed at the bottom of the preheating tank 2, and the multiple inlets are connected to a nitrogen tank. The evenly distributed inlets intermittently blow nitrogen into the preheating tank 2, so that the nitrogen fully contacts with the material in the preheating tank 2 and fully removes the dissolved oxygen in the material.

[0024] In some embodiments, the top of the light-removing column 3 is connected to a first cooler 10, which has two outlets, one of which is connected to a vacuum system 12, and the other is connected to the top of the light-removing column 3 through a first reflux pump 11. The light-removing column 3 is used to remove low-boiling-point impurities in the crude ethylene glycol, and the overhead gas is condensed in the first cooler 10, the non-condensable gas is discharged to the vacuum system 12, and the condensed liquid is refluxed to the top of the light-removing column 3 through the first reflux pump 11.

[0025] Specifically, the bottom of the light-removing column 3 is connected to the middle of an ethylene glycol product column 4 through a kettle liquid delivery pump 13. The top of the ethylene glycol product column 4 is connected to a second cooler 14, which has two outlets, one of which is connected to the vacuum system 12, and the other is connected to the top of the ethylene glycol product column 4 through a second reflux pump 15. The ethylene glycol product column 4 is used to prepare polyester-grade ethylene glycol, and the overhead gas is condensed in the second cooler 14, the non-condensable gas is discharged to the vacuum system 12, and the condensed liquid is refluxed to the top of the ethylene glycol product column 4 through the second reflux pump 15.

[0026] Specifically, the top of the ethylene glycol product column 4 is connected to a crude ethylene glycol removal tank 17 through a first delivery pipeline 16; the upper side of the ethylene glycol product column 4 is connected to a polyester-grade ethylene glycol product tank 19 through a second delivery pipeline 18; and the bottom of the ethylene glycol product column 4 is connected to a waste alcohol removal tank 21 through a third delivery pipeline 20. The first delivery pipeline 16 is provided with a first valve, the second delivery pipeline 18 is provided with a second valve, and the third delivery pipeline 20 is provided with a third valve. By providing valves on the pipelines, the valves can be selectively opened or simultaneously opened according to the working conditions, so as to realize the production of polyester-grade ethylene glycol.

[0027] Further, the stabilizer is sodium borohydride or sodium thiosulfate.

[0028] Further, the pressure in the preheating tank 2 is 0.6-0.8 MPa, and the temperature in the preheating tank 2 is 100-110℃.

[0029] The process of producing polyester grade ethylene glycol by the rectifying device is as follows: crude ethylene glycol and stabilizer are simultaneously delivered into the preheating tank 2, and nitrogen gas is intermittently supplemented into the preheating tank 2 through the nitrogen gas inlet 6 at the bottom of the preheating tank 2 to blow, the pressure in the preheating tank 2 is controlled to be 0.6-0.8 MPa, the temperature in the preheating tank 2 is controlled to be 100-110 DEG C, a small amount of non-condensable gas in the preheating tank 2 is discharged from the condenser 9, the crude ethylene glycol treated by the preheating tank 2 is delivered into the middle part of the light-removing tower 3, the low-boiling-point impurities in the crude ethylene glycol are removed through the light-removing tower 3, the top of the light-removing tower 3 is connected with the first cooler 10, the condensate of the first cooler 10 is delivered to the top reflux of the light-removing tower 3 through the first reflux pump 11, and the non-condensable gas is delivered to the vacuum system 12; the bottom of the light-removing tower 3 is delivered to the middle part of the ethylene glycol product tower 4 through the kettle liquid delivery pump 13 to reduce the heat load of the product tower, the top of the ethylene glycol product tower 4 is connected with the second cooler 14, the condensate of the second cooler 14 is delivered to the top reflux of the ethylene glycol product tower 4 through the second reflux pump 15, and the non-condensable gas is delivered to the vacuum system 12; 98% ethylene glycol product is delivered to the crude ethylene glycol tank 17 through the first delivery pipeline 16 at the top of the ethylene glycol product tower 4, polyester grade ethylene glycol is delivered to the polyester grade ethylene glycol product tank 19 through the second delivery pipeline 18 at the upper side of the ethylene glycol product tower 4, and waste is delivered to the waste alcohol tank 21 through the third delivery pipeline 20 at the bottom of the ethylene glycol product tower 4.

[0030] The above further describes the utility model by means of specific embodiments, but it should be understood that, here specific description, should not be understood as the limitation of the essence and scope of the utility model, various modifications made to the above embodiments by the ordinary skilled in the art after reading the present specification all belong to the range protected by the utility model.

Claims

1. A rectification apparatus for producing polyester-grade ethylene glycol, characterized by comprising: The crude ethylene glycol pipeline, the preheating tank, the light component removal tower and the ethylene glycol product tower are connected in sequence, wherein: The crude ethylene glycol pipeline is connected to the top of the preheating tank, the bottom of the preheating tank is provided with a stabilizer inlet, a nitrogen inlet and a discharge port, the discharge port is connected to the middle part of the light component removal tower, a metering pump is connected to the stabilizer inlet, and a condenser is further connected to the top of the preheating tank.

2. The rectifying apparatus for producing polyester-grade ethylene glycol according to claim 1, characterized by, The nitrogen inlet of the bottom of the preheating tank is provided with a plurality of nitrogen inlets connected to a nitrogen tank.

3. The rectifying apparatus for producing polyester-grade ethylene glycol according to claim 1, wherein The top of the light component removal tower is connected with a first cooler, the first cooler has two outlets, one of which is connected to a vacuum system, and the other is connected to the top of the light component removal tower through a first reflux pump.

4. The rectifying apparatus for producing polyester-grade ethylene glycol according to claim 1, wherein The bottom of the light component removal tower is connected to the middle part of the ethylene glycol product tower through a kettle liquid conveying pump.

5. The rectifying apparatus for producing polyester-grade ethylene glycol according to claim 1, wherein The top of the ethylene glycol product tower is connected with a second cooler, the second cooler has two outlets, one of which is connected to a vacuum system, and the other is connected to the top of the ethylene glycol product tower through a second reflux pump.

6. The rectifying apparatus for producing polyester-grade ethylene glycol according to claim 1, wherein The top of the ethylene glycol product tower is connected to a crude ethylene glycol removal tank through a first conveying pipeline, the upper part of the ethylene glycol product tower is connected to a polyester grade ethylene glycol product tank through a second conveying pipeline, and the bottom of the ethylene glycol product tower is connected to a waste alcohol removal tank through a third conveying pipeline.

7. The rectification apparatus for producing polyester-grade ethylene glycol according to claim 6, characterized by The first conveying pipeline is provided with a first valve, the second conveying pipeline is provided with a second valve, and the third conveying pipeline is provided with a third valve.

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