A method and system for drying and dehydrating acidic gases

Abstract

The present disclosure relates to a method for drying and dehydrating acidic gases. The method includes: S1, performing first heat exchange on the regenerated recycle gas extracted from the catalyst regenerator to obtain the regenerated gas after heat exchange; S2, sending the regenerated gas into a dehydration tank to contact with the acidic gas desiccant filled in the dehydration tank and perform drying and dehydration to obtain the dried regenerated gas; S3, adjusting the oxygen content in the dried regenerated gas to obtain the regenerated gas containing oxygen; and returning the regenerated gas containing oxygen to the catalyst regenerator after performing second heat exchange. The method of the present disclosure can effectively dehydrate the acidic gas containing hydrogen chloride without affecting the hydrogen chloride content in the acidic gas.

Description

Technical Field

[0001] The present disclosure relates to a method and system for drying and dehydrating acidic gases, and is particularly applicable to the drying and dehydrating process of the regeneration recycle gas in the regeneration unit of a continuous reforming unit. Background Art

[0002] In modern refineries, continuous reforming has become an important technology for aromatics and the production of high-octane gasoline, and is also the main source of hydrogen for hydrogenation units. The stable operation of the catalytic reforming unit directly affects the economic benefits of the entire refinery.

[0003] Whether it is UOP CCR, Axens CCR, or domestic SLCR, SCCCR CCR, the catalyst regeneration technology is the core technology. The catalyst regeneration gas of Axens CCR and domestic SLCR, SCCCR CCR adopts a "dry and cold cycle" process. For UOP CCR, the catalyst regeneration gas adopts a "wet and hot cycle" process. The biggest difference between the "dry and cold cycle" and the "wet and hot cycle" is that the "dry and cold cycle" requires high-temperature dechlorination and low-temperature dehydration, and the operating life of the catalyst can reach more than 8 years; the "wet and hot cycle" does not require dechlorination and dehydration, but due to the high water content in the regeneration gas, the specific surface area of the catalyst is lost quickly, and the operating life of the catalyst is only 4 - 6 years.

[0004] In the "dry and cold cycle" technology of Axens CCR and domestic SLCR, SCCCR CCR, the catalyst regeneration gas is drawn out from the upper part of the regenerator, cooled by heat exchange in the coke burning heat exchanger, and then mixed with the lye sent by the regeneration caustic scrubbing recycle pump, so that the chlorine and carbon dioxide in the gas are neutralized with the lye. Next, it is further cooled to 40°C through the regeneration gas recycle aftercooler and enters the regeneration gas caustic scrubbing tower for water washing. At this time, the chlorine in the regeneration gas can be removed to less than 1 μg / L. The gas after dechlorination by caustic scrubbing and water washing is dried by absorbing water in the regeneration circulator dryer, and the water in the regeneration gas is removed to less than 50 μg / L. Then, after being boosted by the recycle compressor, the oxygen content is adjusted by supplementing air, and then heated to 477°C through heat exchange in the regeneration gas heat exchanger and the coke burning electric heater and returned to the coke burner for recycling. However, during the operation process, there are deficiencies in caustic scrubbing dechlorination, such as large investment, complex process flow, difficult operation and control, the need to treat waste water and caustic sludge, and equipment corrosion still exists. After 2000, the solid dechlorination technology of regeneration gas gradually replaced caustic scrubbing dechlorination and achieved good results.

[0005] The use of a high-temperature dechlorination agent for dechlorination fully meets the requirements of the regeneration unit of the continuous reforming unit for dechlorination, simplifies the operating system, has low investment, high economic benefits, reduces the corrosion of equipment pipelines, makes equipment maintenance easier, and the exhaust gas generated can be directly discharged into the atmosphere. The regenerated gas is extracted from the upper part of the regenerator and enters the high-temperature dechlorination tank at a temperature of 520 °C for dechlorination, reducing the hydrogen chloride in the regenerated gas to less than 0.5 μg / L. After being cooled by heat exchange in the coking feed heat exchanger, it is further cooled to 40 °C through the regenerated gas recycle aftercooler and directly enters the regenerated gas recycle compressor for water absorption and drying, removing the water in the regenerated gas to less than 50 μg / L. The regenerated gas recycle compressor boosts the pressure, adjusts the oxygen content by supplementing air, and then returns to the regenerator after the temperature is raised to about 477 °C through heat exchange, and is recycled in this way to achieve the purpose of continuous operation.

[0006] For the dry cold cycle technology of Axens CCR and domestic SLCR and SCCCR CCR, whether it is alkali washing dechlorination or high-temperature solid dechlorination, it is necessary to undergo dechlorination treatment to remove hydrogen chloride in the regenerated gas before the water in the recycle gas can be removed at low temperature. Since the regenerated gas returned to the coking unit does not contain chlorine, it is necessary to supplement the chlorine lost due to carbon burning and dechlorination during the oxychlorination process, increasing the additional consumption of chlorides and being unfavorable to environmental protection.

[0007] For the wet heat cycle technology of UOP's CCR, the catalyst regenerated gas is extracted from the upper part of the coking unit by the regeneration fan, cooled by air cooling, heated to about 4770 °C by the coking electric heater, and then returned to the coking unit and recycled in this way. Due to the absence of a corresponding dehydration treatment process, the water generated during the regeneration of the catalyst will gradually accumulate and reach equilibrium. Industrial operation data shows that the water content in the regenerated gas using the wet heat cycle is as high as about 6%. Regenerating the catalyst in such a high water environment is bound to cause a rapid decrease in the specific surface area of the catalyst and a shortening of the operating life.

[0008] In 2001, UOP launched Chlorsorb TM chlorine adsorption technology. The first application showed that the chloride consumption of the unit decreased by 70%, the HCl content in the regenerated exhaust gas decreased from 2500 μg / L to less than 20 μg / L, and the chloride removal rate was over 99%. The first domestic unit introduced in 2008 was put into production, and by 2020, there were nearly 50 CCR units with Chlorsorb TM chlorine adsorption technology in China. Tracking the operation of the units, it was found that the Chlorsorb dechlorination technology had the following problems: (1) The rate of decrease in the specific surface area of the reforming catalyst was significantly higher than that of the units without Chlorsorb TMFor the reforming catalyst in the dechlorination process, whether it is a domestic catalyst or a UOP catalyst, the decrease in the specific surface area of the catalyst results in a reduction in its chlorine-holding capacity. The amount of chloride that needs to be supplemented during regeneration also increases accordingly, and the operation time of the catalyst is shortened; (2) The air cooler for the vent gas is severely corroded; (3) There is a hidden danger that the tail gas emissions do not meet the standards. In the later stage of the operation of the reforming catalyst, the specific surface area drops to below 140 m 2 / g, leading to a decrease in the chlorine-holding capacity, an increase in the hydrogen chloride content in the regeneration vent gas, a decrease in the chlorine adsorption capacity of the reforming catalyst, and it is possible that the hydrogen chloride in the vent gas exceeds the standard for emission; (4) Since the regeneration vent gas contacts the hydrocarbon-containing reforming catalyst before venting, the total non-methane hydrocarbons in the exhaust gas are greater than the national emission standard (less than 30 μg / L).

[0009] Due to the existence of the above serious problems, domestic similar units have basically cancelled the Chlorsorb TM chlorine adsorption technology and replaced it with solid dechlorination technology.

[0010] The reason is that after the regeneration air of the Chlorsorb TM dechlorination process enters from the cooling zone, it rises to the drying zone. All the air in the drying zone enters the chlorination zone, without vent gas being discharged, and directly enters the regeneration zone. In this way, the air volume in the drying zone and the chlorination zone decreases. Although the amount of water evaporated in the drying zone remains unchanged, the concentration of water brought into the regeneration zone by the air in the drying zone shows a certain degree of increase. The catalyst in the Chlorsorb TM adsorption zone not only adsorbs chlorine in the exhaust gas, but also a large amount of water in the gas. This part of the adsorbed water is released again in the high-temperature regeneration zone and enters the gas phase, resulting in a three-fold increase in the water content of the regeneration recycle gas and a rapid decrease in the catalyst surface area.

[0011] For the "wet heat circulation" technology of UOP's CCR regeneration gas, although the chlorine in the regeneration gas is not removed and is reused, due to the fact that the water in the regeneration gas has not been dried and dehydrated, the water content is as high as 11%. When it contacts the catalyst in a high-temperature environment, the common specific surface area decreases at a faster rate, the chlorine-holding capacity decreases, and the chlorine that needs to be supplemented increases accordingly. Summary of the Invention

[0012] The purpose of the present disclosure is to provide a method that does not affect the hydrogen chloride content in the acidic gas and can effectively dehydrate the acidic gas containing hydrogen chloride.

[0013] To achieve the above purpose, the first aspect of the present disclosure provides a method for drying and dehydrating acidic gas, the method comprising:

[0014] S1. Perform a first heat exchange on the regeneration recycle gas extracted from the catalyst regenerator to obtain the regenerated gas after heat exchange;

[0015] S2. Feed the regeneration gas into a dehydration device to contact with an acidic gas desiccant filled in the dehydration device, and perform drying and dehydration to obtain the dried regeneration gas;

[0016] S3. Adjust the oxygen content in the dried regeneration gas to obtain an oxygen-containing regeneration gas; perform secondary heat exchange on the oxygen-containing regeneration gas and then return it to the catalyst regenerator;

[0017] Wherein, the dehydration device includes a first dehydration drying tank and a second dehydration drying tank, and the first dehydration drying tank and the second dehydration drying tank are used alternately.

[0018] Optionally, when the water content in the dried regeneration gas obtained after passing through the acidic gas desiccant filled in the first dehydration drying tank is greater than 50 μg / L, use the second dehydration drying tank for drying and dehydration.

[0019] Optionally, the regeneration recycle gas contains H2O and HCl; based on the total weight of the regeneration recycle gas, the content of H2O is 0.5 - 12% by weight; the content of HCl in the regeneration recycle gas is 10 - 3000 μg / L.

[0020] Optionally, the acidic gas desiccant is calcium chloride and alumina; wherein, based on the total weight of the acidic gas desiccant, the content of calcium chloride is 80 - 95% by weight, and the content of alumina is 5 - 20% by weight.

[0021] Optionally, the particle size of the acidic gas desiccant is 2 - 5 mm, preferably 3 - 4 mm; the specific surface area is 40 - 100 m 2 / g, and the total pore volume is 0.2 - 0.4 cc / g.

[0022] Optionally, the temperature of the heat-exchanged regeneration gas is 138 - 190 °C, preferably 160 - 180 °C; the temperature of the oxygen-containing regeneration gas after secondary heat exchange is 450 - 490 °C, preferably 470 - 477 °C.

[0023] Optionally, the conditions for the drying and dehydration include: temperature is 50 - 200 °C, preferably 150 - 180 °C; pressure is 0.1 - 1.0 MPa, preferably 0.3 - 0.8 MPa.

[0024] Optionally, the method further includes: when the water content in the dried regeneration gas obtained after passing through the acidic gas desiccant filled in the first dehydration drying tank or the second dehydration drying tank is greater than 50 μg / L, regenerate the acidic gas desiccant to obtain the regenerated acidic gas desiccant; return the regenerated acidic gas desiccant to the first dehydration drying tank or the second dehydration drying tank.

[0025] Optionally, the regeneration is carried out in a nitrogen atmosphere, and the conditions for the regeneration include: the temperature is 260 - 310 °C, preferably 290 - 300 °C; the pressure is 0.1 - 1.0 MPa, preferably 0.3 - 0.8 MPa.

[0026] The second aspect of the present disclosure provides a system suitable for the method of drying and dehydrating acidic gas. The system includes a regenerator, an electric heater, a heat exchanger, and a first drying and dehydrating tank; wherein, the outlet pipeline of the regenerator is connected to the heat exchanger, the first outlet of the heat exchanger is connected to the inlet of the first drying and dehydrating tank, the outlet pipeline of the first drying and dehydrating tank is connected to the second inlet of the heat exchanger, the second outlet of the heat exchanger is connected to the inlet of the electric heater, and the outlet of the electric heater is connected to the inlet of the regenerator; the system further includes a second drying and dehydrating tank; the first dehydration drying tank and the second dehydration drying tank are used alternately.

[0027] Optionally, the system includes a recycle compressor, the inlet pipeline of the recycle compressor is connected to the outlet of the first drying and dehydrating tank, and the outlet pipeline of the recycle compressor is connected to the second inlet of the heat exchanger.

[0028] Optionally, the system includes a regeneration blower, the inlet pipeline of the regeneration blower is connected to the outlet of the regenerator, and the outlet pipeline of the regeneration blower is connected to the first inlet of the heat exchanger.

[0029] Through the above technical solutions, the method of the present disclosure can avoid the loss of chlorine in the regeneration recycle gas and can also dehydrate the water in the regeneration recycle gas to 50 μg / L; and on the basis of delaying the deactivation rate of the reforming catalyst and increasing the catalyst operation life, it has the characteristics of reducing or canceling the fresh chlorine supplement of the reforming catalyst; the method of the present disclosure has the characteristics of continuous regeneration of the acidic gas drying and dehydrating agent and can operate continuously for a long period.

[0030] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0032] Figure 1 is the process flow diagram of Embodiment 1 of the present disclosure;

[0033] Figure 2 is the process flow diagram of Embodiment 2 of the present disclosure.

[0034] Description of the Reference Numerals in the Drawings

[0035] 1 Regenerator

[0036] 2 Electric Heater

[0037] 3 Heat Exchanger

[0038] 4 First Drying and Dewatering Tank

[0039] 5 Circulating Compressor

[0040] 6 Regeneration Blower Detailed Embodiments

[0041] The following provides a detailed description of the specific embodiments of the present disclosure. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present disclosure, and are not intended to limit the present disclosure.

[0042] The first aspect of the present disclosure provides a method for drying and dehydrating acidic gases, the method comprising:

[0043] S1. Perform a first heat exchange on the regeneration recycle gas extracted from the catalyst regenerator to obtain the regenerated gas after heat exchange;

[0044] S2. Feed the regenerated gas into the dehydration device to contact with the acidic gas desiccant filled in the dehydration device and perform drying and dehydration to obtain the dried regenerated gas;

[0045] S3. Adjust the oxygen content in the dried regenerated gas to obtain the oxygen-containing regenerated gas; perform a second heat exchange on the oxygen-containing regenerated gas and then return it to the catalyst regenerator;

[0046] Wherein, the dehydration device includes a first dehydration and drying tank and a second dehydration and drying tank, and the first dehydration and drying tank and the second dehydration and drying tank are used alternately.

[0047] In a preferred embodiment of the present disclosure, when the water content in the dried regenerated gas obtained after passing through the acidic gas desiccant filled in the first dehydration and drying tank is greater than 50 μg / L, the second dehydration and drying tank is used for drying and dehydration.

[0048] According to the present disclosure, the regeneration recycle gas contains H2O and HCl; based on the total weight of the regeneration recycle gas, the content of H2O can be 0.5 - 12% by weight; the content of HCl in the regeneration recycle gas can be 10 - 3000 μg / L.

[0049] According to the present disclosure, the acid gas desiccant may contain calcium chloride and alumina; wherein, based on the total weight of the acid gas desiccant, the content of calcium chloride may be 80-95% by weight, and the content of alumina may be 5-20% by weight. Preferably, the particle size of the acid gas desiccant in the present disclosure may be 2-5 mm, preferably 3-4 mm; the specific surface area is 40-100 m 2 / g, and the total pore volume is 0.2-0.4 cc / g.

[0050] According to the present disclosure, the temperature of the regenerated gas after heat exchange may be 138-190 °C, preferably 160-180 °C; the temperature of the oxygen-containing regenerated gas after the second heat exchange is 450-490 °C, preferably 470-477 °C.

[0051] According to the present disclosure, the conditions for drying and dehydration may include: the temperature is 50-200 °C, preferably 150-180 °C; the pressure is 0.1-1.0 MPa, preferably 0.3-0.8 MPa.

[0052] According to the present disclosure, the method may further include: when the water content in the dried regenerated gas obtained after passing through the acid gas desiccant filled in the first dehydration drying tank or the second dehydration drying tank is greater than 50 μg / L, regenerating the acid gas desiccant to obtain the regenerated acid gas desiccant; returning the regenerated acid gas desiccant to the dehydration tank.

[0053] According to the present disclosure, the regeneration may be carried out in a nitrogen atmosphere, and the conditions for the regeneration may include: the temperature is 260-310 °C, preferably 290-300 °C; the pressure is 0.1-1.0 MPa, preferably 0.3-0.8 MPa.

[0054] The second aspect of the present disclosure provides a system suitable for an acid gas drying and dehydration method. The system includes a regenerator, an electric heater, a heat exchanger, and a first dehydration drying tank; wherein, the outlet pipeline of the regenerator is connected to the heat exchanger, the first outlet of the heat exchanger is connected to the inlet of the first dehydration drying tank, the outlet pipeline of the first dehydration drying tank is connected to the second inlet of the heat exchanger, the second outlet of the heat exchanger is connected to the inlet of the electric heater, and the outlet of the electric heater is connected to the inlet of the regenerator; the system further includes a second dehydration drying tank; the first dehydration drying tank and the second dehydration drying tank are used alternately.

[0055] According to the present disclosure, the system may further include a recycle compressor. The inlet pipeline of the recycle compressor is connected to the outlet of the first dehydration drying tank, and the outlet pipeline of the recycle compressor is connected to the second inlet of the heat exchanger.

[0056] According to the present disclosure, the system may further include a regeneration blower, an inlet pipeline of the regeneration blower is connected to an outlet of the regenerator, and an outlet pipeline of the regeneration blower is connected to a first inlet of the heat exchanger.

[0057] A specific embodiment of the present disclosure is as Figure 1 shown. A system applicable to an acidic gas drying and dehydration method includes a regenerator 1, an electric heater 2, a heat exchanger 3, a first drying and dehydration tank 4, and a circulation compressor 5; an outlet pipeline of the regenerator 1 is connected to a first inlet of the heat exchanger 3, a first outlet of the heat exchanger 3 is connected to an inlet of the first drying and dehydration tank 4, an outlet of the first drying and dehydration tank 4 is connected to an inlet of the circulation compressor 5, an inlet of the circulation compressor 5 is connected to a second inlet of the heat exchanger 3, a second outlet of the heat exchanger 3 is connected to an inlet of the electric heater 2, and an outlet of the electric heater 2 is connected to an inlet of the regenerator 1; the system further includes a spare second drying and dehydration tank; when the water content in the regeneration gas of the acidic gas desiccant filled in the first dehydration drying tank or the second dehydration drying tank is greater than 50 μg / L, the acidic gas desiccant is regenerated, and the second dehydration drying tank is used for drying and dehydration.

[0058] A specific embodiment of the present disclosure is as Figure 2 shown. A system applicable to an acidic gas drying and dehydration method includes a regenerator 1, an electric heater 2, a heat exchanger 3, a first drying and dehydration tank 4, and a regeneration blower 6; an outlet pipeline of the regenerator 1 is connected to an inlet of the regeneration blower 6, an outlet of the regeneration blower 6 is indirectly connected to a first inlet of the heat exchanger 3, a first outlet of the heat exchanger 3 is connected to an inlet of the first drying and dehydration tank 4, an outlet of the first drying and dehydration tank 4 is connected to a second inlet of the heat exchanger 3, a second outlet of the heat exchanger 3 is connected to an inlet of the electric heater 2, and an outlet of the electric heater 2 is connected to an inlet of the regenerator 1; the system further includes a spare second drying and dehydration tank; when the water content in the regeneration gas of the acidic gas desiccant filled in the first dehydration drying tank or the second dehydration drying tank is greater than 50 μg / L, the acidic gas desiccant is regenerated, and the second dehydration drying tank is used for drying and dehydration.

[0059] The present disclosure will be further described in detail below through examples. All raw materials used in the examples can be obtained through commercial channels.

[0060] The acidic gas desiccant used in the examples of the present disclosure contains calcium chloride and alumina; wherein, based on the total weight of the acidic gas desiccant, the content of calcium chloride is 85% by weight, and the content of alumina is 15% by weight.

[0061] Example 1

[0062] This embodiment describes the drying and dehydration process of the regeneration gas for domestic CCR and Axens CCR of the present disclosure. The process flow schematic diagram of this embodiment is shown in Figure 1 In this embodiment, the drying and dehydration tank includes two drying and dehydration tanks. One of the drying and dehydration tanks is in the state of drying and dehydrating the regeneration circulating gas, and the other drying and dehydration tank is in the standby state after regeneration.

[0063] The regeneration circulating gas (containing H2O = 1000 μg / L and HCl = 2000 μg / L) coming out from the bottom of the catalyst regenerator is heat-exchanged in a heat exchanger at a temperature of 500 °C. After the temperature drops to 180 °C, the regeneration gas enters the dehydration tank filled with acidic gas desiccant for water drying and removal. The outlet temperature of the drying tank is controlled above 160 °C. The water content of the regeneration circulating gas coming out from the drying and dehydration tank can be reduced to below 50 μg / L. Then, it passes through the regeneration gas circulation compressor, and fresh dry air is supplemented to adjust the oxygen content in the regeneration gas. Then, it is heat-exchanged in a heat exchanger and electrically heated to raise the temperature of the regeneration circulating gas to 470 °C and return to the upper part of the catalyst regenerator, thus realizing the cyclic drying and dehydration operation of the regeneration gas.

[0064] As the drying and dehydration time increases, the water adsorption capacity of the acidic gas desiccant decreases. The change in the water content at the outlet of the drying tank is monitored in real time. When the water content in the acidic gas at the outlet of the drying tank is greater than 50 μg / L, it indicates that the acidic gas desiccant is saturated with water adsorption and the drying tank needs to be cut out for regeneration. The specific regeneration conditions are as follows: the acidic gas desiccant is treated with nitrogen at 290 °C, and the change in the outlet temperature of the drying tank is monitored. When the outlet temperature of the drying tank reaches 280 °C, the drying is completed, and it is cooled to 180 °C, the drying and dehydration temperature, and then put into use again or cooled to room temperature for standby. In this way, the drying and dehydration - dehydration regeneration are used cyclically. Through the regeneration of the acidic gas desiccant, the operating life of the acidic gas desiccant in this embodiment can reach 2 - 3 years.

[0065] Example 2

[0066] This embodiment is used to describe the drying and dehydration process of the regeneration gas for UOP CCR of the present invention. The process flow schematic diagram of this embodiment is shown in Figure 2 In this embodiment, the drying and dehydration tank includes two drying and dehydration tanks. One of the drying and dehydration tanks is in the state of drying and dehydrating the regeneration circulating gas, and the other drying and dehydration tank is in the standby state after regeneration.

[0067] The regenerated recycle gas (containing 6 wt% H2O and 2500 μg / L HCl) coming out from the top of the catalyst regenerator is heated and cooled by the regenerator fan and heat exchanger, reducing the temperature of the regenerated recycle gas from 550 °C to 180 °C. Then the regenerated gas passes through a drying tank filled with acidic gas drying and dehydrating agent for drying and dehydration. The outlet temperature of the drying tank is controlled above 160 °C, and the water content at the outlet of the drying tank is monitored in real time, controlling the water content at the outlet of the drying tank to be below 50 μg / L. The dried regenerated gas is then heated and cooled by the heat exchanger and electrically heated, raising the temperature of the regenerated recycle gas to 477 °C and returning it to the bottom of the catalyst regenerator, thus realizing the cyclic drying and dehydration operation of the regenerated gas.

[0068] As the drying and dehydration time increases, the water adsorption capacity of the acidic gas drying agent decreases. The change in the water content at the outlet of the drying tank is monitored in real time. When the water content in the acidic gas at the outlet of the drying tank is greater than 50 μg / L, it indicates that the acidic gas drying agent is saturated with adsorbed water and the drying tank needs to be taken out for regeneration. The specific regeneration conditions are as follows: the acidic gas drying agent is treated with nitrogen at 290 °C, and the change in the outlet temperature of the drying tank is monitored. When the outlet temperature of the drying tank reaches 280 °C, the drying is completed, and it is cooled to 180 °C for continued use in the drying and dehydration temperature or cooled to room temperature for standby. Thus, the drying and dehydration - dehydration regeneration is used cyclically. Through the regeneration of the acidic gas drying agent, the operating life of the acidic gas drying agent in this example can reach 2 - 3 years.

[0069] Comparative Example 1

[0070] This comparative example describes the dry and cold cyclic regeneration process of the regenerated gas applied in the reforming unit. The continuous reforming unit used in this disclosure is a domestic continuous reforming unit with an annual output of 1 million tons.

[0071] The regenerated flue gas comes out from the catalyst carbon burning unit, and the hydrogen chloride in the regenerated flue gas is removed to less than 0.5 μg / L through solid dechlorination at a pressure of 0.6 MPa and a temperature of 500 °C. Then the temperature of the regenerated gas is reduced to 40 °C through heat exchange, and the water in the regenerated gas is removed to less than 50 μg / L by contacting with the drying agent at 40 °C. Then it is electrically heated to raise the temperature to 470 °C and returned to the carbon burning unit through the recycle compressor for cyclic use. The drying agent for the regenerated gas is regenerated every 3 days.

[0072] Since this drying and dehydration process requires dechlorination, it causes a large loss of chlorine in the catalyst during the carbon burning process, and it is necessary to supplement the chlorine loss caused by carbon burning dechlorination in the oxychlorination step, resulting in a large chlorine loss.

[0073] Comparative Example 2

[0074] This comparative example is used to describe the wet and hot cycle catalyst regeneration process in the regeneration unit of the UOP reforming unit. The continuous reforming unit used in this disclosure is a 1 million tons / year UOP third-generation CycleMax continuous reforming unit in a certain refinery.

[0075] The regeneration gas exits from the top of the catalyst regenerator, exchanges heat with the regeneration fan and the air cooler at a pressure of 0.35 MPa and a temperature of 550 °C, reduces the temperature to about 450 °C, and then increases the temperature to 470 °C through electric heating and returns to the bottom of the regenerator for such cyclic use.

[0076] Since there is no dehydration in this process, the specific surface area of the catalyst decreases rapidly, and the operating life of the catalyst is only 3 - 6 years.

[0077] The preferred embodiments of the present disclosure have been described in detail above. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0078] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any appropriate manner. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0079] Furthermore, any combination can be made between various different embodiments of the present disclosure as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A method for drying and dehydrating acidic gases, characterized in that, The method includes: S1. Conduct the first heat exchange on the regenerated recycle gas extracted from the catalyst regenerator to obtain the heat-exchanged regenerated gas; S2. Feed the regenerated gas into a dehydration device to contact with the acidic gas desiccant filled in the dehydration device and conduct drying and dehydration to obtain the dried regenerated gas; S3. Adjust the oxygen content in the dried regenerated gas to obtain the oxygen-containing regenerated gas; conduct the second heat exchange on the oxygen-containing regenerated gas and then return it to the catalyst regenerator; wherein, the dehydration device includes a first dehydration drying tank and a second dehydration drying tank, and the first dehydration drying tank and the second dehydration drying tank are used alternately; The temperature of the heat-exchanged regenerated gas is 138 - 190 °C; The regenerated recycle gas contains H2O and HCl; based on the total weight of the regenerated recycle gas, the content of H2O is 0.5 - 12% by weight; the content of HCl in the regenerated recycle gas is 10 - 3000 μg / L; The acidic gas desiccant contains calcium chloride and alumina; based on the total weight of the acidic gas desiccant, the content of calcium chloride is 80 - 95% by weight, and the content of alumina is 5 - 20% by weight.

2. The method according to claim 1, wherein When the water content in the dried regenerated gas obtained after passing through the acidic gas desiccant filled in the first dehydration drying tank is greater than 50 μg / L, use the second dehydration drying tank for drying and dehydration.

3. The method according to claim 1, wherein, The particle size of the acidic gas desiccant is 2 - 5 mm; the specific surface area of the acidic gas desiccant is 40 - 100 m 2 / g, and the total pore volume is 0.2 - 0.4 cc / g.

4. The method according to claim 3, wherein The particle size of the acidic gas desiccant is 3 - 4 mm.

5. The method according to claim 1, wherein The temperature of the heat-exchanged regenerated gas is 160 - 180 °C; The temperature of the oxygen-containing regenerated gas after the second heat exchange is 450 - 490 °C.

6. The method according to claim 5, wherein, The temperature of the oxygen-containing regenerated gas after the second heat exchange is 470 - 477 °C.

7. The method according to claim 1, wherein, The conditions for the drying and dehydration include: temperature is 50 - 200 °C; pressure is 0.1 - 1.0 MPa.

8. The method according to claim 7, wherein, The conditions for the drying and dehydration include: temperature is 150 - 180 °C; pressure is 0.3 - 0.8 MPa.

9. The method according to claim 1, wherein The method further includes: when the water content in the dried regenerated gas obtained after passing through the acidic gas desiccant filled in the first dehydration drying tank or the second dehydration drying tank is greater than 50 μg / L, regenerate the acidic gas desiccant to obtain the regenerated acidic gas desiccant; return the regenerated acidic gas desiccant to the first dehydration drying tank or the second dehydration drying tank; The regeneration is carried out in a nitrogen atmosphere, and the conditions for the regeneration include: temperature is 260 - 310 °C; pressure is 0.1 - 1.0 MPa.

10. The method according to claim 9, wherein, The conditions for the regeneration include: temperature is 290 - 300 °C; pressure is 0.3 - 0.8 MPa.

11. A system applicable to the acidic gas drying and dehydration method described in any one of claims 1-10, characterized in that, The system includes a regenerator, an electric heater, a heat exchanger and a first drying and dehydration tank; Wherein, the outlet pipeline of the regenerator is connected with the heat exchanger, the first outlet of the heat exchanger is connected with the inlet of the first drying and dehydration tank, the outlet pipeline of the first drying and dehydration tank is connected with the second inlet of the heat exchanger, the second outlet of the heat exchanger is connected with the inlet of the electric heater, and the outlet of the electric heater is connected with the inlet of the regenerator; The system further includes a second drying and dehydration tank; the first dehydration and drying tank and the second dehydration and drying tank are used alternately.

12. The system according to claim 11, wherein, The system further includes a recycle compressor, an inlet pipeline of the recycle compressor is connected to an outlet of the first drying and dehydration tank, and an outlet pipeline of the recycle compressor is connected to a second inlet of the heat exchanger.

13. The system according to claim 11, wherein, The system further includes a regeneration blower, an inlet pipeline of the regeneration blower is connected to an outlet of the regenerator, and an outlet pipeline of the regeneration blower is connected to a first inlet of the heat exchanger.

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