A method for preparing an acid gas drying agent from a spent dechlorinating agent

Abstract

The present disclosure relates to a method for preparing an acid gas drying dehydrating agent from waste dechlorination agent, the method comprising: S1, subjecting the waste dechlorination agent to a first calcination treatment under an inert atmosphere to obtain a first material; S2, subjecting the first material to an impregnation treatment in an acid solution and then filtering and washing to obtain a second material; S3, subjecting the second material to a drying treatment and a second calcination treatment; wherein the waste dechlorination agent contains calcium oxides and hydroxides, aluminum oxide, sodium oxide, magnesium oxide, diiron trioxide, and calcium chloride. Using the acid gas drying agent of the present disclosure, the hydrogen chloride content in the gas does not change while dehydrating, and the supplement of chlorine can be reduced.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of desiccant preparation, in particular, to a method for preparing an acid gas drying dehydrating agent from waste dechlorination agent. BACKGROUND

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

[0003] In recent years, reforming technology, especially continuous reforming, has developed rapidly, and the related supporting technology-dechlorination technology is indispensable. There are four parts of the reforming unit that require dechlorination technology, namely: (1) dechlorination technology for pre-hydrogenation of refined naphtha; (2) dechlorination technology for hydrogen produced by reforming; (3) dechlorination technology for chlorine in reformate; (4) dechlorination technology for chlorine in the circulating regeneration gas and vent gas of the continuous reforming regeneration unit.

[0004] The reforming feed needs to be hydrotreated to meet the requirements of the reforming catalyst. The chlorine content in the pre-hydrogenation feed varies depending on the feedstock, with some as high as 150 μg / g or even higher. During the pre-hydrogenation reaction, organic chlorides are converted into hydrogen chloride by hydrogenation, and ammonium chloride is formed by the reaction of hydrogen chloride with ammonia generated during the pre-hydrogenation process. The ammonium chloride deposits at low temperatures, causing corrosion and plugging of the low-temperature parts of heat exchangers, air coolers, and water coolers. To eliminate the effects of chlorine, a dechlorination reactor is added after the pre-hydrogenation reactor, and solid dechlorination technology is used to remove the hydrogen chloride in the pre-hydrogenation product using the reaction waste heat, thereby protecting the normal operation of downstream devices and the performance of related catalysts.

[0005] For reforming units, whether semi-regenerative or continuous reforming catalysts, chlorine components will continuously be lost. To maintain the catalytic performance of the reforming catalyst, organic chlorides need to be continuously injected during operation to control water-chlorine balance. The lost chlorine components of the catalyst exist in the form of hydrogen chloride in the reforming hydrogen and reformate. When this reforming hydrogen containing trace amounts of hydrogen chloride is supplied to downstream devices, it can cause (1) corrosion of downstream equipment; (2) the formation of ammonium chloride by combining with trace amounts of nitrogen, causing plugging and fouling of cooling equipment and circulating compressors, and posing a significant safety risk to the safe operation of the device. At the same time, trace amounts of hydrogen chloride can be adsorbed by the catalyst in the downstream hydrogenation unit, affecting the performance of the hydrogenation catalyst. Therefore, measures must be taken to remove the hydrogen chloride in the reforming hydrogen to eliminate its effects. Solid dechlorination technology for reforming hydrogen can effectively solve the above problems.

[0006] The chlorine in the reformate is the loss of the reforming catalyst to the reformate during the operation, and the content gradually increases with the increase of the operation time of the reforming catalyst, with a fluctuation range of 1 μg / g to 4 μg / g. The presence of this part of chlorine will cause corrosion of the overhead cold exchange equipment of the depentanizer and the debutanizer. When the reformate contains a relatively high amount of ammonium ions, the combination of hydrogen chloride and ammonium chloride will gradually deposit at the low-temperature part of the overhead of the depentanizer and the debutanizer, and accumulate to a certain extent to cause plugging of the equipment. There is also a possibility that the chlorine exists in the dry gas of the reforming unit to cause plugging of the furnace nozzle of the heating furnace, which affects the normal operation of the reforming unit. This situation often occurs in CCR units in recent years, especially in units with a large processing capacity. In addition, when the reformate is used as the raw material for aromatic extraction, the chlorine will affect the adsorption performance of the aromatic adsorbent. Therefore, it is necessary to adopt a solid dechlorination technology to remove the chlorine in the reformate.

[0007] Whether it is UOP CCR, Axens CCR or domestic CCR technology, the regeneration technology of the catalyst is one of the core technologies. Before the 21st century, the dechlorination of the regeneration gas of the continuous reforming unit mostly used alkali washing dechlorination process. It was found during the operation that the alkali washing dechlorination had the disadvantages of large equipment investment, complex process flow, difficult operation control technology, waste water alkali residue needing treatment, and equipment corrosion still existing. Since 2000, the solid dechlorination technology of the regeneration gas has gradually replaced the alkali washing dechlorination, and good results have been obtained.

[0008] Although the solid dechlorination technology has the technical advantages of simple dechlorination process, convenient operation and monitoring of the dechlorination device, and accurate product detection for the catalytic reforming unit, due to the rapid development of the reforming unit, especially the continuous reforming technology in recent years, the annual consumption of the dechlorination agent of the matching dechlorination device is also increasing. It is estimated that the consumption of the dechlorination agent will be about 15,000 tons in 2020. Since the dechlorination agent is a one-time use product and cannot be reused through regeneration, it means that about 15,000 tons of waste dechlorination agent needs to be disposed of every year. The commonly used method is to bury it as a hazardous waste, which not only has huge burying treatment costs, but also has a potential impact on the environment, which does not meet the green development concept of the petrochemical industry.

[0009] During the application of the dechlorination agent, impurities such as iron rust are contained in the treated raw material due to system corrosion and other reasons. These reaction products will deposit on the dechlorination agent to affect the dechlorination performance of the dechlorination agent and the reuse of the waste dechlorination agent.

[0010] The dechlorination principle of dechlorinating agents is to utilize the structure and active components (such as calcium) of the dechlorinating agent to allow hydrogen chloride to be adsorbed onto the dechlorinating agent or react with the active components to form chloride that is fixed onto the dechlorinating agent. Therefore, in the dechlorination reactor bed, the dechlorinating agent that comes into contact with hydrogen chloride first preferentially reacts with or adsorbs hydrogen chloride. The dechlorination reaction is a piston-type reaction from top to bottom. Because the contact time between the dechlorinating agent and hydrogen chloride in the lower part of the bed is reduced, its dechlorination performance is limited by the overall dechlorination effect and is not fully realized. The active components such as calcium in the dechlorinating agent still exist in the form of some metal oxides or hydroxides, which also affects the drying and dehydration performance of the dechlorinating agent. Summary of the Invention

[0011] The purpose of this disclosure is to reuse waste dechlorination agents, thereby reducing the disposal costs of waste dechlorination agents and environmental pollution.

[0012] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing an acidic gas drying and dehydrating agent from waste dechlorination agent, the method comprising:

[0013] S1. The waste dechlorination agent is subjected to a first roasting treatment under an inert atmosphere to obtain the first material;

[0014] S2. The first material is impregnated in acid solution and then filtered and washed to obtain the second material.

[0015] S3. The second material is subjected to drying and second roasting treatment.

[0016] The waste dechlorination agent contains calcium oxide and hydroxide, aluminum oxide, sodium oxide, magnesium oxide, ferric oxide and calcium chloride.

[0017] Optionally, based on the total weight of the waste dechlorination agent, the weight percentage of calcium oxide and hydroxide is 8-70 wt%, aluminum oxide is 30-80 wt%, sodium oxide is 0.4-8 wt%, magnesium oxide is 0.3-2 wt%, ferric oxide is 0.5-2 wt%, and calcium chloride is 20-75 wt%; preferably, the weight percentage of calcium oxide and hydroxide is 10-65 wt%, aluminum oxide is 35-75 wt%, sodium oxide is 0.5-5 wt%, magnesium oxide is 0.5-1.5 wt%, ferric oxide is 1-1.6 wt%, and calcium chloride is 35-70 wt%.

[0018] Optionally, the inert atmosphere is selected from nitrogen atmosphere and argon atmosphere, preferably nitrogen atmosphere.

[0019] Optionally, the pH value of the acid solution is not greater than 3, and the acid solution is selected from hydrochloric acid.

[0020] Optionally, in step S1, the conditions for the first calcination treatment include: a temperature of 450-550℃, preferably 480-520℃; and a time of 3-6 hours, preferably 4-5 hours; in step S2, the conditions for the impregnation treatment include: a temperature of 30-80℃, preferably 50-60℃; and a time of 2-5 hours, preferably 3-4 hours; in step S3, the conditions for the drying treatment include: a temperature of 100-130℃, preferably 110-120℃; and a time of 2-5 hours, preferably 3-4 hours; and the conditions for the second calcination treatment include: a temperature of 400-500℃, preferably 430-450℃; and a time of 2-5 hours, preferably 3-4 hours.

[0021] A second aspect of this disclosure provides an acidic gas drying and dehydrating agent.

[0022] Optionally, the acidic gas drying and dehydrating agent contains 35-70% by weight of calcium chloride.

[0023] Optionally, the particle size of the acidic gas drying and dehydrating agent is 1-5 mm, preferably 2-4 mm; and the specific surface area is 30-100 m². 2 / g, with a total pore volume of 0.15-0.35cc / g.

[0024] A third aspect of this disclosure provides a method for drying and dehydrating an acidic gas containing hydrogen chloride, characterized in that the acidic gas is contacted with an acidic gas drying agent and then dehydrated.

[0025] Optionally, the dehydration and drying conditions include: a temperature of 50-200℃, preferably 150-180℃, and a pressure of 0.1-1.0MPa, preferably 0.3-0.8MPa.

[0026] Optionally, the method further includes: regenerating the acidic gas dehydrating agent when the water content in the acidic gas passing through the acidic gas desiccant is greater than 50 μg / L;

[0027] Optionally, the regeneration conditions include: calcining the acidic gas drying and dehydrating agent to be generated in a nitrogen atmosphere; optionally, the calcination temperature is 260–310°C.

[0028] Through the above technical solution, the method disclosed herein can prepare an acidic gas drying and dehydrating agent from the waste dechlorination agent after use in the reforming dechlorination unit through impurity purification treatment and component optimization. This allows the waste dechlorination agent to be reused, eliminating or reducing the disposal costs and environmental pollution of the waste dechlorination agent. This drying and dehydrating agent can remove water from acidic gases containing hydrogen chloride. For example, it can remove water from acidic gases containing 1-12% water and 1-3000 μg / L hydrogen chloride to 10-50 μg / L, without changing the hydrogen chloride content in the dehydrated gas. Furthermore, this drying and dehydrating agent has good regeneration performance and can be reused.

[0029] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0030] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0031] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing an acidic gas drying and dehydrating agent from waste dechlorination agent, the method comprising:

[0032] S1. The waste dechlorination agent is subjected to a first roasting treatment under an inert atmosphere to obtain the first material;

[0033] S2. The first material is impregnated in acid solution and then filtered and washed to obtain the second material.

[0034] S3. The second material is subjected to drying and second roasting treatment.

[0035] The waste dechlorination agent contains calcium oxide and hydroxide, aluminum oxide, sodium oxide, magnesium oxide, ferric oxide and calcium chloride.

[0036] The specific purification and component optimization method of the acidic gas desiccant prepared from waste dechlorination agent disclosed herein is as follows: the waste dechlorination agent is treated at high temperature under a nitrogen atmosphere to remove the oil and gas adsorbed by the waste dechlorination agent. Then, it is treated with a hydrochloric acid solution of appropriate concentration to remove the rust on the waste dechlorination agent. At the same time, the hydrochloric acid and the calcium oxide and calcium hydroxide in the waste dechlorination agent that have not reacted with hydrogen chloride further react to convert them into calcium chloride. After washing, filtering, drying, and calcining at high temperature to remove the bound water of calcium chloride, the waste dechlorination agent becomes a product mainly composed of anhydrous calcium chloride, thereby obtaining the acidic gas desiccant prepared from waste dechlorination agent disclosed herein.

[0037] The waste dechlorinating agents described in this disclosure are the dechlorinating agents discarded after the solid dechlorination unit of the reforming unit has failed. They include high-temperature dechlorinating agents for pre-hydrogenated products, reforming hydrogen dechlorinating agents, reforming oil dechlorinating agents, and dechlorinating agents for circulating regeneration gas and venting air in continuous reforming regeneration units. They are particularly suitable for high-temperature dechlorinating agents for pre-hydrogenated products, high-temperature dechlorinating agents for regenerated flue gas in reforming units, and reforming hydrogen dechlorinating agents.

[0038] According to this disclosure, based on the total weight of the waste dechlorination agent, the weight percentage of calcium oxide and hydroxide can be 8-70 wt%, aluminum oxide 30-80 wt%, sodium oxide 0.4-8 wt%, magnesium oxide 0.3-2 wt%, ferric oxide 0.5-2 wt%, and calcium chloride 20-75 wt%; preferably, the weight percentage of calcium oxide and hydroxide is 10-65 wt%, aluminum oxide 35-75 wt%, sodium oxide 0.5-5 wt%, magnesium oxide 0.5-1.5 wt%, ferric oxide 1-1.6 wt%, and calcium chloride 35-70 wt%.

[0039] According to this disclosure, the inert atmosphere may be selected from nitrogen atmosphere and argon atmosphere, preferably nitrogen atmosphere.

[0040] According to this disclosure, the pH value of the acid solution is preferably not greater than 3, and the acid solution may be selected from hydrochloric acid.

[0041] According to this disclosure, in step S1, the conditions for the first calcination treatment include: a temperature of 450-550℃, preferably 480-520℃; and a time of 3-6 hours, preferably 4-5 hours; in step S2, the conditions for the impregnation treatment include: a temperature of 30-80℃, preferably 50-60℃; and a time of 2-5 hours, preferably 3-4 hours; in step S3, the conditions for the drying treatment include: a temperature of 100-130℃, preferably 110-120℃; and a time of 2-5 hours, preferably 3-4 hours; and the conditions for the second calcination treatment include: a temperature of 400-500℃, preferably 430-450℃; and a time of 2-5 hours, preferably 3-4 hours.

[0042] A second aspect of this disclosure provides an acidic gas drying and dehydrating agent.

[0043] According to this disclosure, the acidic gas drying and dehydrating agent may contain 35-70% by weight of calcium chloride.

[0044] According to this disclosure, the particle size of the acidic gas drying and dehydrating agent can be 1-5 mm, preferably 2-4 mm; the specific surface area is 30-100 m².2 / g, with a total pore volume of 0.15-0.35cc / g.

[0045] The acidic gas desiccant disclosed herein can be used for drying and dehydrating the circulating regenerated gas in the regeneration unit of a continuous reforming unit, and can also be used for drying and dehydrating other similar gases.

[0046] A third aspect of this disclosure provides a method for drying and dehydrating an acidic gas containing hydrogen chloride, characterized in that the acidic gas is contacted with a dehydrating agent and then dehydrated and dried.

[0047] According to this disclosure, the dehydration and drying conditions may include: a temperature of 50-200°C, preferably 150-180°C, and a pressure of 0.1-1.0 MPa, preferably 0.3-0.8 MPa.

[0048] The acidic gas desiccant prepared from waste dechlorination agent disclosed herein can be contacted with acidic gas at a temperature of 50-200°C, preferably 150-180°C, to reduce the water content in the regenerated gas from 1-12% to below 50 μg / L, while keeping the hydrogen chloride content in the regenerated gas unchanged. This greatly reduces the need for chlorine replenishment, and also reduces chlorine consumption while reusing the waste dechlorination agent, thus improving the environmental protection level of the device.

[0049] The acidic gas desiccant prepared from waste dechlorination agent disclosed herein also has excellent regeneration performance. As a preferred embodiment of this disclosure, the method further includes: regenerating the acidic gas dehydrating agent when the water content in the acidic gas passing through the acidic gas desiccant is greater than 50 μg / L.

[0050] Preferably, the regeneration conditions may include: treating the acidic gaseous desiccant for adsorbing water disclosed herein with nitrogen at a temperature of 260-310°C, preferably 290-300°C, to remove the adsorbed water and allow it to be reused.

[0051] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0052] Example 1

[0053] To eliminate the corrosion of downstream units by chlorides in the reforming feedstock, a dechlorination reactor is connected in series after the pre-hydrogenation reactor. Utilizing the residual heat from the pre-hydrogenation reaction (typically between 250-320℃), hydrogen chloride reacts with the alkali metal calcium on the dechlorinating agent to form calcium chloride, thereby removing hydrogen chloride from the reforming feedstock. This also prevents the reaction of hydrogen chloride and ammonia to form ammonium chloride, which can clog the unit. When the chlorine content at the dechlorination reactor outlet exceeds 0.5 μg / g, the dechlorination tank breaks down, requiring the dechlorinating agent to be unloaded and refilled with fresh dechlorinating agent before reuse. 100g of the aforementioned waste dechlorinating agent was taken, and the elemental content of the sample was determined by X-ray fluorescence analysis (XRF). The composition is shown in Table 1.

[0054] The waste dechlorinating agent in this embodiment is subjected to a first roasting under a nitrogen atmosphere to remove the oil and gas adsorbed by the waste dechlorinating agent, resulting in a first material. The conditions for the first roasting include: treatment at a high temperature of 500°C for 4 hours and cooling to room temperature; 500 ml of hydrochloric acid solution with an equivalent concentration of 0.5 is placed in a beaker, and the first material is slowly added for impregnation treatment for 4 hours, the pH value of the solution is measured and kept below 3, and then filtered and washed to obtain a second material; the second material is then subjected to a drying treatment and a second roasting treatment. The conditions for the drying treatment include: drying in a drying oven at 120°C for 4 hours, and the conditions for the second roasting treatment include: roasting in a muffle furnace at 450°C for 4 hours and then cooling to room temperature; the acidic gas desiccant prepared from the waste pre-hydrogenated high-temperature dechlorinating agent obtained in this embodiment is designated as A.

[0055] Example 2

[0056] Under normal operating conditions, the reformed hydrogen contains approximately 1-3 μg / L of hydrogen chloride and trace amounts of ammonium chloride. This hydrogen chloride and ammonium chloride gradually deposit in the low-temperature section of the reformed hydrogen circulation compressor, accumulating to a certain level and causing compressor blockage and shutdown. Simultaneously, ammonium chloride decomposes into hydrochloric acid under the action of condensate, causing under-deposit corrosion. The low-temperature dechlorination process involves re-contacting the reformed hydrogen into a dechlorination reactor. The dechlorination operating temperature is between 4-40℃, but is significantly affected by ambient temperature (seasonal temperature). Hydrogen chloride and ammonium chloride are removed from the reformed hydrogen through adsorption or chemical reaction, thus avoiding blockage and corrosion of the hydrogen circulation compressor. When the chlorine content at the dechlorination reactor outlet exceeds 0.5 μg / L, the dechlorination tank permeates, requiring the dechlorinating agent to be unloaded and refilled with fresh dechlorinating agent before reuse. 100g of the aforementioned waste dechlorinating agent was taken, and the elemental content in the sample was determined by X-ray fluorescence analysis (XRF). The composition is shown in Table 2.

[0057] The waste dechlorinating agent in this embodiment is subjected to a first roasting under a nitrogen atmosphere to remove the oil and gas adsorbed by the waste dechlorinating agent, resulting in a first material. The conditions for the first roasting include: treatment at 500°C for 4 hours and cooling to room temperature; 500 ml of hydrochloric acid solution with an equivalent concentration of 0.2 is placed in a beaker, and the first material is slowly added for impregnation treatment, which is carried out for 4 hours. The pH value of the solution is measured and kept below 3. Then, the solution is filtered and washed to obtain a second material. The second material is then subjected to a drying treatment and a second roasting treatment. The conditions for the drying treatment include: drying in a drying oven at 120°C for 4 hours. The conditions for the second roasting treatment include: roasting in a muffle furnace at 450°C for 4 hours and then cooling to room temperature. The acidic gas desiccant prepared from the waste reforming hydrogen dechlorinating agent in this embodiment is designated as B.

[0058] Example 3

[0059] The dechlorination technology for regenerated flue gas in reforming units includes dechlorination of recirculated regenerated gas and vented air. Typically, the chloride content in the regenerated gas ranges from approximately 20 μg / L to 2500 μg / L. To eliminate the corrosive effects of chloride in the reforming feedstock on downstream units, a dechlorination reactor is required. Utilizing the residual heat from regeneration (temperature typically between 200-500℃), hydrogen chloride reacts with the alkali metal calcium on the dechlorinating agent to form calcium chloride, thereby removing hydrogen chloride from the regenerated gas. When the chlorine content at the dechlorination reactor outlet exceeds 0.5 μg / g, the dechlorination tank breaks down, and the dechlorinating agent needs to be unloaded and refilled with fresh dechlorinating agent before reuse. 100g of the aforementioned waste dechlorinating agent was taken, and the elemental content in the sample was determined by X-ray fluorescence analysis (XRF). The composition is shown in Table 3.

[0060] The waste dechlorinating agent in this embodiment is subjected to a first roasting under a nitrogen atmosphere to remove the oil and gas adsorbed by the waste dechlorinating agent, resulting in a first material. The conditions for the first roasting include: treatment at 500°C for 4 hours and cooling to room temperature; 500 ml of hydrochloric acid solution with an equivalent concentration of 0.5 is placed in a beaker, and the waste dechlorinating agent is slowly added for impregnation treatment for 4 hours, the pH value of the solution is measured and kept below 3, and then filtered and washed to obtain a second material; the second material is then subjected to drying treatment and a second roasting treatment; the conditions for the drying treatment include: drying in a drying oven at 120°C for 4 hours, and the conditions for the second roasting treatment include: roasting in a muffle furnace at 450°C for 4 hours and cooling to room temperature; the acidic gas desiccant prepared from the waste regenerated gas dechlorinating agent in this embodiment is designated as C.

[0061] Test Example 1

[0062] 100g of the acidic gas desiccant obtained in Examples 1-3 was placed in a tubular container with ceramic balls at both ends. The container was heated to 160°C under a drying nitrogen atmosphere, and then an acidic gas with a flow rate of 1500ml / h was introduced. The composition of the acidic gas was as follows: N2 = 88%, CO2 = 14%, O2 = 2%, H2O = 6%, HCl = 1500μg / L. During the contact process, the water in the gas and the calcium chloride in the desiccant combined to form hydrated calcium chloride, while hydrogen chloride did not react with calcium chloride, thus removing water from the acidic gas. The water content in the exhaust gas was measured in real time. The drying process ended when the water content was 50μg / L. The water content adsorbed by various desiccants was measured, and the results are shown in Table 4.

[0063] Example 4

[0064] Take the water-containing desiccant A from Test Example 1 after it has been in contact with acidic gas. In a dry nitrogen environment, heat up and control the inlet temperature to 290°C. In the early stage of regeneration, the outlet temperature is not high due to the evaporation of adsorbed water. As time increases, the outlet temperature will gradually increase as the water content of the desiccant decreases. When the outlet temperature of the drying tank reaches 280°C, the regeneration ends. Reduce the reaction temperature to 160°C and switch to the water-containing acidic gas from Example 4 for reuse, realizing the cycle of drying and dehydration-dehydration regeneration.

[0065] Comparative Example 1

[0066] The dehydration process of regenerated flue gas in a 700,000-ton / year continuous reforming unit of a refinery is as follows: The regenerated flue gas comes out of the catalyst burner and undergoes solid dechlorination at a pressure of 0.6 MPa and a temperature of 500°C to remove hydrogen chloride from the regenerated flue gas to below 0.5 μg / L. Then, the temperature of the regenerated gas is reduced to 40°C through heat exchange. Under the condition of 40°C, it comes into contact with a desiccant to remove water from the regenerated gas to below 50 μg / L. Then, the temperature is raised to 500°C by electric heating and returned to the burner by a circulating compressor. This cycle is repeated, and the regenerated gas is regenerated with a desiccant every 3 days.

[0067] Because this drying and dehydration process requires dechlorination, the chlorine loss of the catalyst during the char burning process is significant. The chlorine loss due to char burning dechlorination needs to be replenished in the oxychlorination step, resulting in significant chlorine loss and energy consumption.

[0068] Table 1

[0069] Dechlorination agent component Composition m% Na2O 0.65 MgO 0.55 Al2O3 8.56 CaO 57.00 Cl 31.68 Fe2O3 1.56

[0070] Table 2

[0071] Dechlorination agent component Composition m% Na2O 1.35 MgO 0.85 Al2O3 59.89 CaO 25.00 Cl 11.68 Fe2O3 1.23

[0072] Table 3

[0073]

[0074]

[0075] Table 4

[0076] Drier number Water absorption, m% A 30 B 16 C 33

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

[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0079] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing an acidic gas drying and dehydrating agent from waste dechlorination agent, characterized in that, The method includes: S1. The waste dechlorination agent is subjected to a first roasting treatment under an inert atmosphere to obtain the first material; S2. The first material is impregnated in an acid solution and then filtered and washed to obtain the second material; the pH value of the acid solution is not greater than 3, and the acid solution is selected from hydrochloric acid. S3. The second material is subjected to drying and second roasting treatment. The waste dechlorinating agent is the dechlorinating agent discarded after the solid dechlorination unit of the reforming unit has failed; the waste dechlorinating agent contains calcium oxide and hydroxide, aluminum oxide, sodium oxide, magnesium oxide, ferric oxide and calcium chloride; based on the total weight of the waste dechlorinating agent, the weight percentage of calcium oxide and hydroxide is 10-65 wt%, the weight percentage of aluminum oxide is 35-75 wt%, the weight percentage of sodium oxide is 0.5-5 wt%, the weight percentage of magnesium oxide is 0.5-1.5 wt%, the weight percentage of ferric oxide is 1-1.6 wt%, and the weight percentage of calcium chloride is 35-70 wt%. In step S2, the conditions for the impregnation treatment include: a temperature of 30-80℃ and a time of 2-5 hours.

2. The method according to claim 1, wherein, The inert atmosphere is selected from either nitrogen atmosphere or argon atmosphere.

3. The method according to claim 2, wherein, The inert atmosphere is a nitrogen atmosphere.

4. The method according to claim 1, wherein, In step S1, the conditions for the first calcination treatment include: a temperature of 450-550℃ and a time of 3-6 hours; In step S3, the drying conditions include: a temperature of 100-130℃ and a time of 2-5 hours; the second calcination conditions include: a temperature of 400-500℃ and a time of 2-5 hours.

5. The method according to claim 4, wherein, In step S1, the conditions for the first calcination treatment include: a temperature of 480-520℃ and a time of 4-5 hours; In step S2, the conditions for the impregnation treatment include: a temperature of 50-60°C and a time of 3-4 hours; In step S3, the drying conditions include: a temperature of 110-120℃ and a time of 3-4 hours; the second calcination conditions include: a temperature of 430-450℃ and a time of 3-4 hours.

6. An acidic gas drying and dehydrating agent, characterized in that, The acidic gas drying and dehydrating agent is prepared according to any one of claims 1-5.

7. The acidic gas drying and dehydrating agent according to claim 6, wherein, The acidic gas drying and dehydrating agent contains 35-70% by weight of calcium chloride.

8. The acidic gas drying and dehydrating agent according to claim 6, wherein, The acidic gas drying and dehydrating agent has a particle size of 1-5 mm and a specific surface area of ​​30-100 m². 2 / g.

9. The acidic gas drying and dehydrating agent according to claim 8, wherein, The acidic gas drying and dehydrating agent has a particle size of 2-4 mm and a specific surface area of ​​30-100 m². 2 / g, with a total pore volume of 0.15-0.35 cc / g.

10. A method for drying and dehydrating an acidic gas containing hydrogen chloride, characterized in that, The acidic gas is contacted with an acidic gas drying agent prepared by the method for preparing an acidic gas drying agent from waste dechlorination agent as described in any one of claims 1-5 or the acidic gas drying agent as described in any one of claims 7-9 and dehydrated. The dehydration and drying conditions include: a temperature of 50-200℃ and a pressure of 0.1-1.0 MPa.

11. The method according to claim 10, wherein, The dehydration and drying conditions include: a temperature of 150-180℃ and a pressure of 0.3-0.8 MPa.

12. The method according to claim 10, wherein, The method further includes: regenerating the acidic gas dehydrating agent when the water content in the acidic gas passing through the acidic gas desiccant is greater than 50 µg / L.

13. The method according to claim 12, wherein, The regeneration conditions include: calcining the acidic gas drying and dehydrating agent to be generated in a nitrogen atmosphere; the calcination temperature is 260-310°C.

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