Method for removing excessive EO in decarburization unit of EO / EG device

Abstract

The invention provides a method for removing excessive EO in a decarburization unit of an EO / EG device. A tower plate or a filler layer is arranged at the upper end of the water scrubber, gas such as circulating gas and EO steam from the bottom of the water scrubber can be washed by washing water when passing through the tower plate or the filler layer, and a large amount of EO is dissolved in the washing water and taken away. The washing water is provided by condensate water of the regenerated gas separation gas or fresh desalted water is directly adopted. And sending the washed aqueous solution containing high-concentration EO to sewage treatment. The method is used for removing the EO, the EO is removed before entering the decarburization alkali liquor, the water consumption is low, the removal amount is high, the washing water can be sent out of sewage for treatment and can also be sent to continue to recover the EO in the water, and the method is suitable for a decarburization unit on an EO / EG device, simple in process and low in cost. The problems that the EO content in the decarburization solution is too high and the whole unit discharges too much sewage are solved.

Description

Technical Field

[0001] The invention discloses a method for removing EO in a decarbonization unit of an EO / EG device, belongs to the technical field of energy conservation and environmental protection, and is a method for removing EO and other impurities in circulating gas from a decarbonization unit of an EO / EG device. Background Art

[0002] The technologies related to ethylene oxide / ethylene glycol (EO / EG) mainly include the ethylene method, which uses ethylene and oxygen as raw materials to generate ethylene oxide through oxidation reaction, and ethylene oxide is converted into ethylene glycol through traditional hydration process or catalytic hydrolysis process.

[0003] Currently, the dominant process for industrial application of ethylene oxide / ethylene glycol in the world is the direct oxidation of ethylene over a silver catalyst to produce ethylene oxide and the hydration of ethylene oxide to produce ethylene glycol.

[0004] As one of the components of the ethylene oxide / ethylene glycol unit, the CO2 removal system is mainly used to remove the byproduct CO2 from the EO reaction circulating gas flow to keep the component concentration in the circulating gas system stable.

[0005] Since there is oxygen in the circulating gas system, a hot potassium carbonate solution system is required for CO2 removal. In the circulating gas entering the decarbonization system, the EO content entering the decarbonization system is significantly exceeded due to the failure to remove EO completely in the previous EO refining system. Usually, the EO content should be controlled at around 5ppm, but in actual operation, it often exceeds this content by a large amount, reaching 50-100ppm. In this way, a large amount of EO will be brought into the decarbonization system and react with water to form EG. If there is no appropriate method to remove EG, EG will continue to accumulate in the decarbonization system. According to general requirements, the content of ethylene glycol in the decarbonization solution cannot exceed 2% of the total mass of the decarbonization solution, but in actual production, some factories can reach up to 12% of the mass of the entire decarbonization solution, which can easily cause the solution to foam and overflow, affecting the decarbonization effect and the safe operation of the device.

[0006] Therefore, it is particularly important to find a suitable method for removing alcohol. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a method for removing excess EO in a decarbonization unit of an EO / EG device.

[0008] The present invention adds several layers of plates or fillers to the circulating gas water washing tower, introduces washing water on the plates, and most of the circulating gas is discharged from the top of the water washing tower after washing. Part of the EO is washed off by the circulating water, but because the EO in the circulating water is close to saturation, more EO will be taken out of the water washing tower. If a stream of washing water is introduced at the top of the water washing tower, the EO vapor will be washed off by the washing water when passing through the plates, thereby achieving the purpose of removing EO. Since the EO content at the top of the water washing tower is relatively high in the decarbonization system, a washing section is set here, which can wash out more organic matter, with high efficiency and relatively small amount of water used, reducing the difficulty of subsequent wastewater treatment.

[0009] The main technical solution of the present invention is a method for removing excess EO in a decarbonization unit of an EO / EG device, characterized in that a tower plate or a packing layer is arranged at the upper end of a water washing tower, and washing water is used to wash excess EO in the circulating gas.

[0010] Furthermore, the number of tower plates is 1-10, or the number of packing layers is 1-10.

[0011] Furthermore, the washing water used is fresh desalted water, or condensed water supplied from other places in the device.

[0012] Furthermore, the fresh desalted water or condensed water supplied from other places in the device is cooled to below 30° C. and then used for washing the circulating gas.

[0013] Preferably, the temperature is reduced by using an ice machine or other methods.

[0014] Furthermore, the washing water rich in EO after washing is directly sent to sewage treatment.

[0015] Furthermore, the washing water rich in EO after washing is sent for recycling treatment to recover the high-concentration EO therein, and the recycled washing water is then sent for sewage treatment.

[0016] Furthermore, the washing tower plate or packing layer is arranged between the circulating water inlet and the demister at the top of the washing tower.

[0017] Furthermore, the washing water is introduced from the uppermost tower plate or packing, and is drawn out from the lowermost tower plate or packing to be sent for subsequent treatment.

[0018] The method of the present invention is used to remove EO, and EO is removed at the place with higher concentration in the whole decarbonization device, with less water consumption and high removal amount. The washing water can be sent to sewage treatment or to continue to recover organic matter in the water.

[0019] The method of the invention is applicable to the decarbonation unit on the EO / EG device, has a simple process, and solves the problem of excessive EO in the decarbonation solution and excessive wastewater discharge of the entire unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a simplified process flow diagram of a method for removing excess EO in a decarbonization unit of an EO / EG device according to an embodiment of the present invention.

[0021] In the figure, 1—circulating gas comes from outside the boundary, 2—circulating gas exits the water washing tower, 3—desalted water comes from outside the boundary, 4—washing water dehydration treatment system, 5—circulating water exits the water washing tower, 6—circulating water enters the water washing tower, 7—cooling water enters the circulating water cooler, T101—circulating gas water washing tower, A101—circulating water air cooler, E101—circulating water water cooler, P101—desalted water booster pump, P102—circulating water pump. Implementation

[0022] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Example

[0023] like Figure 1 As shown, a method for removing excess EO in a decarbonization unit of an EO / EG device mainly includes a circulating gas water scrubber T101, a circulating gas water scrubber T101, a circulating water air cooler A101, a circulating water water cooler E101, a desalted water booster pump P101, a circulating water pump P102, a condensed water / desalted water inlet water scrubber washing section, a washing section drainage dewatering treatment, an organic matter removal tower plate / packing layer at the top of the water scrubber, etc.

[0024] In the embodiment, a plurality of trays or packing layers are added to the circulating gas water scrubber, and the trays or packing layers are arranged between the circulating water inlet and the demister at the top of the water scrubber. Washing water is introduced from the top of the trays or packing layers, and circulating gases such as hydrocarbons and water vapor are discharged from the top of the water scrubber. EO vapor with a higher concentration will be washed down by the washing water when passing through the trays, and then drawn out from the bottom trays or packing layers and sent to subsequent treatment, thereby achieving the purpose of removing organic matter. Example 1

[0025] A three-layer tray is set at the top of the water washing tower, where the total gas volume of the circulating gas before entering the tray for washing is about 4094.248Kmol / h, and the main components are methane, ethylene, ethane, nitrogen, argon, carbon dioxide, oxygen and water. The specific components are shown in Table 1 (before water washing). The operating pressure is about 1.7MpaG, and the gas temperature is about 40℃. 3 tons of regenerated gas condensate water is introduced on the tray. The condensate water is cooled to about 30℃ by an air cooler and used to wash the circulating gas. After the circulating gas is washed with washing water, the EO concentration decreases by about 91%. The specific components after washing are shown in Table 1 (after water washing). After the circulating gas is washed with water, the organic content of the subsequent absorption tower is greatly reduced. In addition, the washing water rich in organic matter is sent to water treatment. The organic concentration is high and the water volume is small, which is easy to handle.

[0026] Table 1 Comparison of circulating gas components before and after water washing Example 2

[0027] A three-layer tray is set at the top of the water washing tower, where the total gas volume of the circulating gas before entering the tray for washing is about 4094.248Kmol / h, and the main components are methane, ethylene, ethane, nitrogen, argon, carbon dioxide, oxygen and water. The specific components are shown in Table 2 (before water washing). The operating pressure is about 1.9MpaG, and the gas temperature is about 40℃. 3 tons of regenerated gas condensate water is introduced on the tray. The condensate water is cooled to about 20℃ by an ice machine and used to wash the circulating gas. After the circulating gas is washed with washing water, the EO concentration decreases by about 93%. The specific components after washing are shown in Table 2 (after water washing). After the circulating gas is washed with water, the organic content of the subsequent absorption tower is greatly reduced. In addition, the washing water rich in organic matter is sent to water treatment. The organic concentration is high and the water volume is small, which is easy to handle.

[0028] Table 2 Comparison of circulating gas components before and after water washing Example 3

[0029] A layer of packing is set at the top of the water washing tower, where the total gas volume of the circulating gas before entering the tower plate for washing is about 4094.248Kmol / h, and the main components are methane, ethylene, ethane, nitrogen, argon, carbon dioxide, oxygen and water. The operating pressure is about 1.9MpaG, and the gas temperature is about 10℃. 3 tons of regenerated gas condensed water is introduced on the tower plate. The condensed water is cooled to about 10℃ by an ice machine and used to wash the circulating gas. After the circulating gas is washed with washing water, the EO concentration drops by about 96%. After the circulating gas is washed with water, the EO content of the subsequent absorption tower is greatly reduced. In addition, the washing water rich in EO is sent to water treatment. The EO concentration is high and the water volume is small, which is easy to handle. Example 4

[0030] Two layers of packing are set at the top of the water washing tower, where the total gas volume of the circulating gas before entering the tower plate for washing is about 4094.248Kmol / h, and the main components are methane, ethylene, ethane, nitrogen, argon, carbon dioxide, oxygen and water. The operating pressure is about 1.9MpaG, and the gas temperature is about 40℃. 3 tons of regenerated gas condensate water is introduced on the tower plate. The condensate water is cooled to about 30℃ by an air cooler and used to wash the circulating gas. After the circulating gas is washed with washing water, the EO concentration drops by about 95%. After the circulating gas is washed with water, the EO content of the subsequent absorption tower is greatly reduced. In addition, the washing water rich in EO is sent to water treatment, with a high organic concentration and a small amount of water, which is easy to handle. Example 5

[0031] Two layers of packing are set at the top of the water washing tower, where the total gas volume of the circulating gas before entering the tower plate for washing is about 4094.248Kmol / h, and the main components are methane, ethylene, ethane, nitrogen, argon, carbon dioxide, oxygen and water. The operating pressure is about 1.7MpaG, and the gas temperature is about 40℃. 5 tons of regenerated gas condensate water is introduced on the tower plate. The condensate water is cooled to about 30℃ by an air cooler and used to wash the circulating gas. After the circulating gas is washed with washing water, the EO concentration drops by about 93%. After the circulating gas is washed with water, the EO content of the subsequent absorption tower is greatly reduced. In addition, the washing water rich in EO is sent to water treatment. The EO concentration is high and the water volume is small, which is easy to handle. Example 6

[0032] Two layers of packing are set at the top of the water washing tower. The total gas volume of the circulating gas before entering the tower plate for washing is about 4094.248Kmol / h. The main components are methane, ethylene, ethane, nitrogen, argon, carbon dioxide, oxygen and water. The operating pressure is about 1.9MpaG, and the gas temperature is about 40℃. 5 tons of regenerated gas condensed water are introduced on the tower plate. The condensed water is cooled to about 20℃ by an ice machine and used to wash the circulating gas. After the circulating gas is washed with washing water, the organic matter concentration decreases by about 97%. After the circulating gas is washed with water, the EO content of the subsequent absorption tower is greatly reduced. In addition, the washing water rich in EO is sent to water treatment. The EO concentration is high and the water volume is small, which is easy to handle. Example 7

[0033] Five layers of packing are set on the top of the water washing tower. The total gas volume of the circulating gas before entering the tower plate for washing is about 4094.248Kmol / h. The main components are methane, ethylene, ethane, nitrogen, argon, carbon dioxide, oxygen and water. The operating pressure is about 1.9MpaG, and the gas temperature is about 40℃. 10 tons of regenerated gas condensed water are introduced on the tower plate. The condensed water is cooled to about 20℃ by an ice machine and used to wash the circulating gas. After the circulating gas is washed with washing water, the EO concentration drops by about 99%. After the circulating gas is washed with water, the EO content of the subsequent absorption tower is greatly reduced. In addition, the washing water rich in EO is sent to water treatment. The EO concentration is high and the water volume is small, which is easy to handle.

Claims

1. A method for removing excess EO in a decarbonization unit of an EO / EG device, characterized in that: A tower plate or packing layer is set at the upper end of the water washing tower, and the washing water is used to wash the excess EO in the circulating gas.

2. The method according to claim 1, characterized in that: The number of tower plates is 1 to 10, or the number of packing layers is 1 to 10.

3. The method according to claim 1, characterized in that: The washing water used is fresh desalted water or condensed water supplied from other places in the device.

4. The method according to claim 3, characterized in that: The fresh desalted water or condensed water supplied from other places in the device is cooled to below 30° C. and then used for washing the circulating gas.

5. The method according to claim 4, characterized in that: The cooling method includes using an ice machine or other methods to cool the temperature.

6. The method according to claim 1, characterized in that: After washing, the washing water rich in EO is directly sent to sewage treatment.

7. The method according to claim 1, characterized in that: After washing, the washing water rich in EO is sent for recycling treatment to recover the high-concentration EO therein, and the recycled washing water is then sent for sewage treatment.

8. The method according to claim 1 or 2, characterized in that: The washing tower plate or packing layer is arranged between the circulating water inlet and the demister at the top of the washing tower.

9. The method according to claim 1 or 2, characterized in that: The washing water is introduced from the uppermost tower plate or packing, and is drawn out from the lowermost tower plate or packing for subsequent treatment.

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