Pure terephthalic acid (PTA) refining emptying tail gas organic matter purification device

Abstract

The utility model discloses a purified terephthalic acid (PTA) refining emptying tail gas organic matter purification device, which belongs to the technical field of chemical environmental protection equipment and is characterized in that a circulating pump c is communicated with a cooler through a pipeline, the cooler is communicated with the upper part of a washing tower a through a pipeline, and the washing tower a is communicated with a washing tower b through a pipeline; the bottom of the washing tower b is communicated with the circulating pump a through a pipeline, the dilute alkali tank is communicated with the circulating pump b through a pipeline, the circulating pump b is communicated with the middle of the washing tower a through a pipeline, a cooler is arranged at the upper part of the washing tower b, and an emptying chimney is arranged between the washing tower a and the washing tower b.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical environmental protection equipment, in particular to a PTA refined exhaust gas organic matter purification device. Background Art

[0002] While PTA production capacity continues to improve, optimize, and expand, various consumption factors are also being optimized. In existing advanced PTA plants, the elimination of the drying unit in the oxidation section of older process units resulted in a certain amount of organic matter in the crude TA entering the refining section. Furthermore, the acetic acid and other organic matter in the recycled process water in the system, after reaction, flash crystallization, and other steps, resulted in elevated levels of methyl acetate, acetic acid, and non-methane hydrocarbons in the exhaust gas.

[0003] At present, the country advocates green and environmentally friendly production enterprises, insists on reducing the content of organic components in the exhaust gas of PTA units, improving the exhaust standards, and meeting the requirements of sustainable and healthy development.

[0004] In current PTA production operations, refined venting tail gas originates from flash steam release from the crystallizer and various pressure vessel safety accessories. Most of this flash steam is water vapor and non-condensable gases, including acetic acid, methyl acetate, and methanol. The presence of this non-condensable gas contributes to elevated levels of non-methane total hydrocarbons and acetic acid in the vented gas phase.

[0005] In order to solve the above technical problems, a washing tower is added to perform alkali washing and low-temperature water washing on the organic impurities in the vented gas phase and then discharge it to purify the vented tail gas. Utility Model Content

[0006] The purpose of the utility model is to solve at least one of the technical problems existing in the prior art, and discloses a PTA refined exhaust gas organic matter purification device, the technical solution adopted is as follows:

[0007] A device for purifying organic matter in PTA refined exhaust gas comprises a circulating pump a, a circulating pump b, a circulating pump c and a washing tower a.

[0008] The core improvements of the present utility model are as follows: the circulating pump c is connected to the cooler through a pipeline, the cooler is connected to the upper part of the washing tower a through a pipeline, the washing tower a is connected to the washing tower b through a pipeline, the bottom of the washing tower b is connected to the circulating pump a through a pipeline, the dilute alkali tank is connected to the circulating pump b through a pipeline, the circulating pump b is connected to the middle of the washing tower a through a pipeline, the upper part of the washing tower b is provided with a cooler a, and an air vent chimney is provided between the washing tower a and the washing tower b.

[0009] The filler washing tower a of the utility model is made of 304L, with two layers

[0010] It adopts rectangular saddle type packing, made of 304L material, and adopts high pressure interlock protection for emergency discharge. The lower packing is equipped with a sodium hydroxide pipeline with a concentration of 5%, and the upper packing is equipped with a low-temperature production water pipeline. The production water is cooled to form low-temperature water.

[0011] The working principle of this utility model is as follows:

[0012] After the system flash steam enters the washing tower b, it is refluxed through the tower bottom circulation pump a as the primary spray to spray and wash the dust particles entrained in the gas phase.

[0013] The washed non-condensable gas and uncooled steam enter cooler a, where they are cooled by cooling water. Most of the steam can be converted from gas to liquid and enter the bottom of the tower. The upper end of the cooler is equipped with a normal temperature annular process water spray for further washing.

[0014] The gas after washing is basically non-condensable gas. There is a switch valve before the gas directly enters the vent chimney. The valve is equipped with pressure interlock protection. When the system has an emergency discharge, the discharged flash steam and non-condensable gas cannot be completely washed by the packed tower, causing the pressure to rise to the interlock value. The valve is opened for release and the valve is closed when the pressure returns to normal.

[0015] During normal operation, a very small amount of non-condensable gas, carrying organic impurities, enters the packed scrubber. From bottom to top, it first passes through the lower tower packing layer, where it undergoes sufficient reverse contact with the 5% alkali packing stacked in the rectangular saddle. The alkali solution removes some of the organic impurities. The non-condensable gas then continues upward into the upper tower packing layer, where it undergoes reverse contact with the low-temperature production water. This fully utilizes the packing layer to increase the contact area, allowing for low-temperature scrubbing. After scrubbing, the purified non-condensable gas enters the vent chimney and is released into the atmosphere.

[0016] Compared with the existing technology, the present invention has the following advantages: By using the present invention, the alkaline washing process uses NaOH to react with organic matter and then discharges the waste liquid into the sewage collection tank. The impurities contained in the untreated gas are washed with low-temperature produced water. By changing the washing water temperature, the vent gas temperature change is measured to obtain the following data:

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0019] Figure 1 This is a working principle diagram of the utility model; DETAILED DESCRIPTION

[0020] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0021] Example 1

[0022] Reference Figure 1 As shown,

[0023] A PTA refining and venting tail gas organic matter purification device includes a circulating pump a2, a circulating pump b4, a circulating pump c7 and a washing tower a3, wherein the circulating pump c7 is connected to a cooler 6 through a pipeline, the cooler 6 is connected to the upper part of the washing tower a3 through a pipeline, the washing tower a3 is connected to the washing tower b1 through a pipeline, the bottom of the washing tower b1 is connected to the circulating pump a2 through a pipeline, the diluted alkali tank 5 is connected to the circulating pump b4 through a pipeline, the circulating pump b4 is connected to the middle of the washing tower a3 through a pipeline, a venting chimney 8 is provided between the washing tower a3 and the washing tower b1, a cooler a9 is provided on the upper part of the washing tower b1, and the upper end of the cooler a9 is provided with a normal temperature annular process water spray for further washing.

[0024] The working principle of this utility model is as follows:

[0025] After the system flash steam enters the washing tower b1, it is refluxed through the tower bottom circulation pump a2 as the primary spray to spray and wash the dust particles entrained in the gas phase.

[0026] After washing, the non-condensable gas and uncooled steam enter cooler a9, where they are cooled by cooling water. Most of the steam can be converted from gas to liquid and enter the bottom of the tower. The upper end of cooler a9 is equipped with a normal temperature annular process water spray for further washing.

[0027] The gas after washing is basically non-condensable gas. A switch valve is provided before the gas directly enters the vent chimney 8. The valve is provided with pressure interlock protection. When an emergency discharge occurs in the system, the discharged flash steam and non-condensable gas cannot be completely washed by the packed tower, causing the pressure to rise to the interlock value. When the valve is opened for release, the pressure is released and the valve is closed when the pressure returns to normal.

[0028] During normal operation, a minimal amount of non-condensable gas, carrying organic impurities, enters packed scrubber 3. From bottom to top, it first passes through the lower tower packing layer, where it undergoes sufficient countercurrent contact with the 5% alkali packing stacked in the rectangular saddle. The alkali solution removes some of the organic impurities. The non-condensable gas then continues upward into the upper tower packing layer, where it undergoes countercurrent contact with low-temperature produced water. This utilizes the packing layer to increase contact area, allowing for low-temperature scrubbing. After scrubbing, the purified non-condensable gas enters vent chimney 8 and is released into the atmosphere.

[0029] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A PTA refined exhaust gas organic matter purification device, comprising a circulating pump a (2), a circulating pump b (4), a circulating pump c (7) and a washing tower a (3), characterized in that: The circulating pump c (7) is connected to the cooler (6) through a pipeline, the cooler (6) is connected to the upper part of the washing tower a (3) through a pipeline, the washing tower a (3) is connected to the washing tower b (1) through a pipeline, the bottom of the washing tower b (1) is connected to the circulating pump a (2) through a pipeline, the diluted alkali tank (5) is connected to the circulating pump b (4) through a pipeline, the circulating pump b (4) is connected to the middle of the washing tower a (3) through a pipeline, and an air discharge chimney (8) is provided between the washing tower a (3) and the washing tower b (1).

2. A PTA refining and venting tail gas organic matter purification device as claimed in claim 1, characterized in that, A cooler a (9) is provided on the upper portion of the washing tower b (1).

3. A PTA refining and venting tail gas organic matter purification device as claimed in claim 1, characterized in that, The upper end of the cooler a (9) is provided with a normal temperature annular process water spray for further washing.

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