Alcohol ketone tail gas environment-friendly nitrogen making device

Abstract

The utility model relates to an environment-friendly nitrogen-making device for alcohol ketone tail gas. The environment-friendly nitrogen-making device comprises a tail gas compression unit, a catalytic oxidation purification unit, a freeze dehydration unit, a pressure swing adsorption unit, a nitrogen storage and conveying unit and a nitrogen purification unit, the technology is characterized in that all units are connected in sequence, and specifically, a tail gas compression unit comprises a tail gas buffer tank, a filter, a compressor, a cooler and a liquid separator; the catalytic oxidation purification unit comprises a heat exchanger, a heater, a reactor, a catalyst and a water cooler; the freezing dehydration unit comprises a refrigerating unit, a refrigerator and a water segregator; the pressure swing adsorption unit comprises an adsorber, an adsorbent, a vacuum pump and a desorption gas buffer tank; the nitrogen storage and conveying unit comprises a nitrogen buffer tank and a nitrogen pipe network. According to the technology, the alcohol ketone tail gas can be purified and recycled to be used for producing nitrogen, environment-friendly emission reaches the standard, meanwhile, high-purity nitrogen is recycled, and environmental pollution and resource waste are reduced.

Description

Technical Field

[0001] The utility model relates to an environmental protection nitrogen production device for alcohol-ketone tail gas. Background Art

[0002] In petrochemical production, cyclohexane oxidation can prepare cyclohexanone and cyclohexanol, which are intermediate raw materials for producing important chemical products such as caprolactam and adipic acid. Using the cyclohexane non-catalytic oxidation method, with cyclohexane as the raw material, a mixture of cyclohexanol and cyclohexanone is produced by oxidation with lean oxygen air; the tail gas of the alcohol-ketone unit is a type of tail gas in the adipic acid production device. The main components of the high-pressure tail gas generated by the oxidation reaction of the alcohol-ketone unit and the low-pressure tail gas generated during the pre-concentration process are both nitrogen containing a certain proportion of cyclohexane non-condensable gas; in order to recover cyclohexane in the tail gas, a high-pressure washing tower and a low-pressure washing tower are used in production to wash the high-pressure tail gas and the low-pressure tail gas. In the past, the washed high- and low-pressure alcohol-ketone tail gases were simply treated and then discharged.

[0003] Since the main component of the tail gas of this alcohol-ketone unit is nitrogen, accounting for more than 95%, and the rest are components such as oxygen, carbon monoxide, carbon dioxide, methane, ethane, and cyclohexane, it has a high recovery value.

[0004] Therefore, an environmental protection nitrogen production device for alcohol-ketone tail gas is needed, which can purify and recover the alcohol-ketone tail gas and then use it as nitrogen for production. It can not only solve the problem of meeting environmental protection emission standards, but also recover high-purity nitrogen, turning waste into treasure and avoiding environmental pollution and resource waste. Summary of the Utility Model

[0005] The purpose of the utility model is to solve the above-mentioned deficiencies of the prior art, and provide an environmental protection nitrogen production device for alcohol-ketone tail gas. By means of catalytic oxidation and pressure swing adsorption, this device can remove harmful substances and impurities in the tail gas of the alcohol-ketone unit while preparing high-purity nitrogen for the production device. The following are the specific solutions:

[0006] An environmental protection nitrogen production device for alcohol-ketone tail gas includes a tail gas compression unit, a catalytic oxidation purification unit, a freezing dehydration unit, a pressure swing adsorption unit, a nitrogen storage and transportation unit, and a nitrogen purification unit connected in sequence. The tail gas compression unit includes a tail gas buffer tank, a filter, a compressor, a cooler, and a liquid separator; the catalytic oxidation purification unit includes a heat exchanger, a heater, a reactor, a catalyst, and a water cooler; the freezing dehydration unit includes a refrigeration unit, a freezer, and a water separator; the pressure swing adsorption unit includes an adsorber, an adsorbent, a vacuum pump, and a desorbed gas buffer tank; the nitrogen storage and transportation unit includes a nitrogen buffer tank and a nitrogen pipeline network.

[0007] Furthermore, the outlet of the tail gas buffer tank is connected to the inlet of the filter, the outlet of the filter is connected to the compressor, the compressor is provided with a cooler and a liquid separator, and the compressor is one of a centrifugal compressor, a positive displacement compressor or a magnetic levitation compressor.

[0008] Furthermore, one outlet of the compressor is connected to a heat exchanger, the outlet of the heat exchanger is connected to a heater, the outlet of the heater is connected to a reactor, the reactor is provided with a catalyst, the outlet of the reactor is connected to the heat exchanger, and the other outlet of the heat exchanger is connected to a water cooler. The heater is one of an electric heater, a steam heater or a gas heater.

[0009] Furthermore, the water cooler is connected to a water separator, and a refrigerant and a refrigerator are sequentially connected between the water cooler and the water separator.

[0010] Furthermore, the outlet of the water separator is sequentially connected to at least 4 adsorbers, adsorbents are provided in the adsorbers, the outlet of the water separator is also connected to a vacuum pump, the outlet of the vacuum pump is connected to a desorbed gas buffer tank, the vacuum pump is one of a water ring type, a screw type, a reciprocating type or a roots type, and the pressure swing adsorption unit includes 4 adsorbers. After multiple switching and pressure equalization, carbon dioxide and oxygen components in the tail gas are removed; after the tail gas enters the first adsorber, a pressure boosting process is first carried out, and clean nitrogen from other adsorbers is pressure equalized with the first adsorber. At this pressure, carbon dioxide and oxygen components are gradually adsorbed in the pores of the adsorbent; after multiple pressure equalizations, when the adsorption fronts of carbon dioxide and oxygen reach the reserved section at the outlet of the bed layer, the feed valve and the product gas outlet valve of the adsorber are closed, and the adsorption is stopped; the adsorption bed starts to turn into the regeneration process; after the adsorption process is completed, the process of sequentially discharging the higher pressure gas in the tower along the adsorption direction into other lower pressure towers that have completed regeneration is not only a pressure reduction process, but also recovers the nitrogen in the dead space of the adsorption bed layer; after the pressure equalization process is over, the pressure of the adsorption tower is still about 0.5 MPa(G), and at this time, the impurity adsorption front has not reached the top of the bed layer yet, so the adsorption bed can be further desorbed by pumping negative pressure vacuum with a vacuum pump, so that the impurity components in the adsorbent can be completely desorbed;

[0011] The adsorbent of the pressure swing adsorption unit uses an adsorbent specifically developed for the adsorbed components, uses various adsorption materials with different ratios of aluminum, silicon, carbon, etc., has a very high adsorption capacity for impurity components, and is very easy to regenerate. The adsorbent adopts a dense phase packing technology, which can further reduce the adsorption dead space and improve the product yield.

[0012] Furthermore, the outlet of the adsorber is connected to a nitrogen purification unit.

[0013] Further, the outlet of the nitrogen purification unit is connected to a nitrogen buffer tank, and the outlet of the nitrogen buffer tank is connected to a nitrogen pipeline network.

[0014] Beneficial effects: Recycling and treating the tail gas of the alcohol-ketone plant can avoid environmental pollution. By purifying nitrogen using the characteristic of high nitrogen content in the tail gas, turning waste into treasure, it is more economical, reasonable, and encouraging than the conventional treatment of tail gas to meet the discharge standards, and also effectively reduces the total amount of waste gas emissions of the enterprise.

[0015] The catalytic oxidation purification unit includes a heat exchanger, a heater, distribution ceramic balls, a catalyst, a catalyst support, and supporting temperature detection instruments. The catalyst uses a noble metal catalyst, and the catalytic oxidation efficiency for hydrocarbons and carbon monoxide reaches more than 99%. The catalyst can operate for a long time under the condition that the flue gas temperature does not exceed 600 °C. At the same time, the catalyst should be able to withstand the test of an operating temperature of 650 °C for no less than 8 hours without any damage. The catalyst uses granular catalyst, which can achieve higher treatment efficiency compared with honeycomb catalysts. Layers of ceramic balls with different specifications are arranged above and below the catalyst to ensure uniform gas distribution.

[0016] The catalytic oxidation purification unit uses a heat exchanger to recover the heat after the catalytic oxidation reaction, saving energy consumption, and the heat recovery efficiency can reach 70 - 90%.

[0017] The catalytic oxidation heater can adopt various indirect or direct heating methods such as electric heating, steam heating, and heating furnace heating. Its function is to raise the temperature of the tail gas to reach the reaction temperature required for catalytic oxidation, and the material used can at least withstand a high temperature of 600 °C. Description of the Drawings

[0018] Figure 1 is a schematic pipeline diagram of an environmental protection nitrogen production device for alcohol-ketone tail gas;

[0019] In the figure: 6, nitrogen purification unit; 101, tail gas buffer tank; 102, filter; 103, compressor; 104, cooler; 105, liquid separator; 201, heat exchanger; 202, heater; 203, reactor; 204, catalyst; 205, water cooler; 301, refrigeration unit; 302, freezer; 303, water separator; 401, adsorber; 402, adsorbent; 403, vacuum pump; 404, desorbed gas buffer tank; 501, nitrogen buffer tank; 502, nitrogen pipeline network. Detailed Embodiments

[0020] To deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0021] In this embodiment:

[0022] Please refer to Figure 1 ,an environmental protection nitrogen production device for ketol tail gas, which includes a tail gas compression unit, a catalytic oxidation purification unit, a freezing dehydration unit, a pressure swing adsorption unit, a nitrogen storage and transportation unit, and a nitrogen purification unit 6 connected in sequence. The tail gas compression unit includes a tail gas buffer tank 101, a filter 102, a compressor 103, a cooler 104, and a liquid separator 105; the catalytic oxidation purification unit includes a heat exchanger 201, a heater 202, a reactor 203, a catalyst 204, and a water cooler 205; the freezing dehydration unit includes a refrigeration unit 301, a freezer 302, and a water separator 303; the pressure swing adsorption unit includes an adsorber 401, an adsorbent 402, a vacuum pump 403, and a desorbed gas buffer tank 404; the nitrogen storage and transportation unit includes a nitrogen buffer tank 501 and a nitrogen pipeline network 502.

[0023] The outlet of the tail gas buffer tank 101 is connected to the inlet of the filter 102, the outlet of the filter 102 is connected to the compressor 103, the cooler 104 and the liquid separator 105 are arranged in the compressor 103, and the compressor 103 is one of a centrifugal compressor, a positive displacement compressor, or a magnetic levitation compressor.

[0024] One outlet of the compressor 103 is connected to the heat exchanger 201, the outlet of the heat exchanger 201 is connected to the heater 202, the outlet of the heater 202 is connected to the reactor 203, the catalyst 204 is arranged in the reactor 203, the outlet of the reactor 203 is connected to the heat exchanger 201, and the other outlet of the heat exchanger 201 is connected to the water cooler 205. The heater 202 is one of an electric heater 202, a steam heater 202, or a gas heater 202. The catalyst 204 is a granular catalyst 204, and multiple layers of porcelain balls with different specifications are arranged above and below the catalyst 204.

[0025] The water cooler 205 is connected to the water separator 303. A refrigerant and a freezer 302 are connected in sequence between the water cooler 205 and the water separator 303. The outlet of the water separator 303 is connected to at least 4 adsorbers 401 in sequence. The adsorbent 402 is arranged in each adsorber 401. The outlet of the water separator 303 is also connected to the vacuum pump 403. The outlet of the vacuum pump 403 is connected to the desorbed gas buffer tank 404. The vacuum pump 403 is one of a water ring type, a screw type, a reciprocating type, or a roots type. The outlet of the adsorber 401 is connected to the nitrogen purification unit 6. The outlet of the nitrogen purification unit 6 is connected to the nitrogen buffer tank 501. The outlet of the nitrogen buffer tank 501 is connected to the nitrogen pipeline network 502.

[0026] Implementation example:

[0027] The tail gas of the ketol device enters the compressor 103 after buffering and filtering. After being pressurized by the compressor 103, the tail gas reaches the pressure required by the downstream process unit, and after cooling and liquid separation, it is sent to the catalytic oxidation purification unit for treatment.

[0028] After the tail gas is heated to the reaction temperature by the heat exchanger 201 and the heater 202, it enters the reactor 203 to remove combustible components on the surface of the catalyst 204, converting hydrocarbons, carbon monoxide, and impurity components into water and carbon dioxide. After separating saturated moisture through the water cooler 205, it enters the freeze dehydration unit.

[0029] The freeze dehydration unit cools the tail gas to below -20°C through the refrigeration unit 301 to further remove moisture in the tail gas.

[0030] The pressure swing adsorption unit selectively adsorbs carbon dioxide, oxygen, and other impurity components in the tail gas on the surface of the adsorbent 402 through multiple equal-pressure reverse release processes, desorbs them after being evacuated by the vacuum pump 403, and discharges them to the atmosphere through the desorbed gas buffer tank 404. The clean high-purity nitrogen is then sent to the nitrogen storage and transportation unit.

[0031] The nitrogen storage and transportation unit includes a nitrogen buffer tank 501 and a nitrogen pipeline network 502, serving as a buffer and supply unit for nitrogen products.

[0032] As Figure 1 shown, the tail gas of the alcohol-ketone plant is transported from the upstream plant to the tail gas recovery and treatment plant. After stabilizing the pressure through the tail gas buffer tank 101, it removes solid particulate impurities in the tail gas through the filter 102, and is pressurized to 0.3 - 1.0 MPag by the compressor 103 for transportation to the next process for purification treatment. The temperature of the tail gas will rise after compression. To avoid exceeding the allowable operating temperature of the compressor 103, coolers 104 and liquid separators 105 are provided between stages and at the outlet of the compressor 103 to keep the tail gas temperature at about 40°C and separate the liquid phase components.

[0033] The compressed tail gas enters the catalytic oxidation purification unit, exchanges heat with the tail gas after catalytic oxidation purification, recovering heat while preliminarily heating the tail gas. Then the tail gas is electrically heated to 350 - 500°C required for the reaction and enters the catalytic oxidation reactor 203. In the catalytic oxidation reactor 203, distribution porcelain balls and noble metal catalyst 204 are provided, which can oxidize hydrocarbons, carbon monoxide, and combustible components in the tail gas into harmless and pollution-free water and carbon dioxide. Using the granular noble metal catalyst 204 can ensure the removal rate of combustible components. The temperature of the tail gas after purification treatment is about 100 - 300°C. After recovering heat through the heat exchanger 201 and cooling down through the water cooler 205, it is sent to the freeze dehydration unit.

[0034] The freeze dehydration unit uses Freon as the refrigerant. Through compression refrigeration and heat exchange, it can cool the tail gas to below -20°C and further remove the moisture in the tail gas to below 1 ppmV.

[0035] After removing combustible components and moisture, the main components of the alcohol-ketone tail gas are nitrogen, oxygen, and carbon dioxide. The nitrogen component can be effectively separated through the pressure swing adsorption process. The pressure swing adsorption process uses high-pressure adsorption and vacuum regeneration, with a high nitrogen recovery rate and low comprehensive energy consumption. The pressure swing adsorption process adopts multiple equalization steps, with a large number of steps, a high purification gas recovery rate, and greater energy savings. When the tail gas enters the adsorber 401 under pressure, the impurity components of carbon dioxide and oxygen in the tail gas are selectively adsorbed on the surface of the adsorbent 402, while nitrogen is not adsorbed. High-purity nitrogen is discharged from the top of the adsorber 401 as a product to the nitrogen storage and transportation unit. After the adsorbent 402 is saturated with adsorption, it starts the reverse pressure reduction process. The impurity components of carbon dioxide and oxygen adsorbed in the pores of the adsorbent 402 are gradually released, and finally desorbed by the vacuum pump 403 after being evacuated. After separating the entrained liquid phase, it is emptied through the desorbed gas buffer tank 404. The nitrogen at the outlet is sent to the factory nitrogen pipeline network 502 after being stabilized by the buffer tank.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. An environmental protection nitrogen production device for ketol tail gas, characterized in that, It includes a tail gas compression unit, a catalytic oxidation purification unit, a freezing dehydration unit, a pressure swing adsorption unit, a nitrogen storage and transportation unit, and a nitrogen purification unit that are connected in sequence. The tail gas compression unit includes a tail gas buffer tank, a filter, a compressor, a cooler, and a liquid separator; the catalytic oxidation purification unit includes a heat exchanger, a heater, a reactor, a catalyst, and a water cooler; the freezing dehydration unit includes a refrigeration unit, a freezer, and a water separator; the pressure swing adsorption unit includes an adsorber, an adsorbent, a vacuum pump, and a desorbed gas buffer tank; the nitrogen storage and transportation unit includes a nitrogen buffer tank and a nitrogen pipeline network.

2. The environmental protection nitrogen production device for alcohol-ketone tail gas according to claim 1, characterized in that , the outlet of the tail gas buffer tank is connected to the inlet of the filter, the outlet of the filter is connected to the compressor, the cooler and the liquid separator are arranged in the compressor, and the compressor is one of a centrifugal compressor, a positive displacement compressor, or a magnetic levitation compressor.

3. The nitrogen production device for environmental protection of alcohol-ketone tail gas according to claim 1, characterized in that, One outlet of the compressor is connected to the heat exchanger, the outlet of the heat exchanger is connected to the heater, the outlet of the heater is connected to the reactor, the catalyst is arranged in the reactor, the outlet of the reactor is connected to the heat exchanger, the other outlet of the heat exchanger is connected to the water cooler, the heater is one of an electric heater, a steam heater, or a gas heater, the catalyst adopts a granular catalyst, and multiple layers of porcelain balls with different specifications are arranged above and below the catalyst.

4. An environmental protection nitrogen production device for alcohol-ketone tail gas according to claim 1, characterized in that, The water cooler is connected to the water separator, and a refrigerant and a freezer are connected in sequence between the water cooler and the water separator.

5. An environmentally friendly nitrogen production device for alcohol-ketone tail gas according to claim 1, characterized in that, The outlet of the water separator is connected to at least 4 adsorbers in sequence, the adsorbent is arranged in each adsorber, the outlet of the water separator is also connected to the vacuum pump, the outlet of the vacuum pump is connected to the desorbed gas buffer tank, and the vacuum pump is one of a water ring type, a screw type, a reciprocating type, or a roots type.

6. The nitrogen production device for environmental protection of alcohol-ketone tail gas according to claim 1, characterized in that, The outlet of the adsorber is connected to the nitrogen purification unit.

7. An environmentally friendly nitrogen production device for alcohol-ketone tail gas according to claim 1, characterized in that, The outlet of the nitrogen purification unit is connected to the nitrogen buffer tank, and the outlet of the nitrogen buffer tank is connected to the nitrogen pipeline network.

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