CN1136997C - A kind of catalyst continuous regeneration method - Google Patents

Abstract

A catalyst continuous regeneration method, the catalyst to be raw passes through the buffer zone, charcoal burning zone, oxychlorination zone and roasting zone of the regenerator successively downwards, the regeneration gas first enters the lower space surrounded by the outer screen and the inner wall of the regenerator, Radially through the lower catalyst bed, mixed with supplementary normal temperature inert gas and dry air in the space enclosed by the inner screen, then radially through the upper catalyst bed, and enter the space enclosed by the outer screen and the inner wall of the regenerator The upper space leads out to the regenerator, and returns to the charcoal burning area of the regenerator for recycling after purification and drying. The method enables the catalyst to be regenerated at a lower temperature and lower water content.

Description

A kind of catalyst continuous regeneration method

Technical field

The invention relates to a regeneration method of a hydrocarbon conversion catalyst, more specifically, a catalyst continuous regeneration method.

Background technique

Catalytic reforming is a hydrocarbon conversion process. It uses high-octane gasoline and aromatics as its main products, and produces cheap hydrogen as a by-product. The main chemical reactions that occur include dehydrogenation, cyclodehydrogenation, isomerization, Cracking reaction and coking reaction, etc., in which the coke generated by the coking reaction is deposited on the surface of the catalyst, which reduces the activity of the catalyst, and requires a regeneration process to restore the activity of the catalyst. The regeneration process generally includes processes such as charcoal burning, chlorination renewal, roasting and reduction. The process of burning charcoal is to use oxygen-containing gas to burn off the coke deposited on the catalyst, and at the same time take away the heat released by combustion. The chlorination renewal process is to replenish the chlorine components lost on the catalyst, and at the same time, the active metal components on the catalyst are oxidized and evenly distributed on the surface of the catalyst carrier. The calcination process removes the moisture contained in the catalyst. The reduction process is to reduce the oxidized metal active components in the hydrogen atmosphere.

After the moving bed technology is applied to the hydrocarbon conversion process, the circulation of the catalyst between the reactor and the regenerator is realized, thereby achieving the purpose of continuous regeneration of the catalyst and maintaining the activity of the catalyst at a high level. The regenerator of the continuous regeneration system of hydrocarbon conversion catalyst is generally composed of charcoal burning zone and roasting zone, while the regenerator of continuous reforming catalyst often needs to increase the oxychlorination zone to supplement the chlorine component lost on the catalyst and make the active metal form Divide and redistribute. The main structure of the charcoal burning area is a radial bed, and the catalyst moves down at a slow speed by gravity in the annular structure bed, and the oxygen-containing regeneration gas passes through the catalyst bed in the radial direction, thereby realizing a continuous charcoal burning process. The oxychlorination zone has two structures: radial bed and axial bed, while the roasting zone is generally an axial structure bed.

The service life of the hydrocarbon conversion catalyst mainly depends on the rate of decrease of its specific surface area, and the main factors affecting the decrease of its specific surface area are the humidity of the regeneration gas, the regeneration temperature and the residence time of the catalyst in the high temperature zone. Because the charcoal burning process is carried out under high temperature conditions, and the coke deposited on the catalyst will generate water vapor during the combustion process, and the charcoal burning is completed in a water-containing environment, so the charcoal burning process of the regeneration of the hydrocarbon conversion catalyst will affect the catalyst. major processes of life.

For the radial charcoal bed, since the catalyst has a relatively high char content at the entrance of the bed, when in contact with the oxygen-containing regeneration gas that passes radially through the catalyst bed, the charcoal burnt releases a large amount of heat, and gradually Accumulated at the inner screen, so that the temperature of the bed near the inner screen in the upper part of the bed is higher, while in the lower part of the bed, because the carbon content on the catalyst is low, the heat released by charcoal burning is less, and the temperature of the bed is higher. Liter is smaller. Therefore, for the entire bed, the high-temperature zone in the upper part of the bed is likely to have an adverse effect on the performance of the catalyst, while the temperature in the lower bed is lower and has the potential to further improve the charcoal burning ability, so properly adjust the temperature in the bed. The temperature distribution will have a positive effect on protecting the performance of the catalyst and prolonging the service life of the catalyst.

In the regeneration process provided by USP4,578,370 and CN86102807A, the charcoal burning area of the regenerator is a radial bed structure, and the catalyst moves down slowly by gravity in the annular space, and the gas space at the screen outside the charcoal burning area is divided into two parts , the corresponding upper catalyst bed mainly plays the role of burning charcoal, and the lower catalyst bed plays the role of heating the catalyst, so that the catalyst enters the oxychlorination zone at a higher temperature, and the regeneration gas is led out of the regenerator after converging in the central tube, and a small amount of air is vented After passing through the regeneration fan, it is divided into two strands, one of which enters the upper catalyst bed after passing through the air cooler and heater, and the other directly enters the lower catalyst bed. There is no drying system in the circulation loop of the regeneration gas. The water content in the regeneration gas is adjusted by supplementary air and venting of the regeneration gas, and finally stabilizes to an equilibrium value. The water content in the regeneration gas is always maintained at a relatively high level. , have an adverse effect on the performance of the catalyst.

In the regeneration process provided by USP4,859,643 and USP5,277,880, the carbon burning zone of the regenerator is a conical structure, and the bed has different thicknesses at different axial positions, which can improve the gas distribution along the axial position of the bed, The upper bed is thinner and distributes a large amount of gas, while the lower bed is thicker and distributes less gas, which can better meet the needs of oxygen in different axial positions, and at the same time, the residence time of the catalyst in the high-temperature area on the upper part of the bed is reduced . However, there is no drying system in the circulation loop of the regeneration gas, and the regeneration gas has a relatively high water content.

In the regeneration process provided by USP4,880,604 and USP4,977,119, the charcoal burning area of the regenerator is a bar-shaped structure, and the catalyst moves down slowly in the bar-shaped space by gravity, and the upper and lower parts of the outer screen have different openings rate, so that the regeneration gas has different distributions along the axial direction, the upper bed distributes a larger amount of gas, and the lower bed distributes a smaller amount of gas, which is conducive to meeting the needs of oxygen in different axial positions. However, there is no drying system in the circulation loop of the regeneration gas, and the regeneration gas has a relatively high water content.

In the regeneration process introduced in the above-mentioned patent, since there is no drying system in the regeneration gas circuit, the regeneration cycle gas has a relatively high water content. Although it is mentioned in USP4,578,370 and CN86102807A that the regeneration gas enters the charcoal-burning area in stages, it is still equivalent to the entire cross-section passing through the outer screen of the charcoal-burning area for the total regeneration gas. There is a high-temperature zone at the inner screen on the upper part of the layer, and the charcoal regeneration process of the catalyst is completed in a high-temperature, high-water-content environment. This high-temperature, high-water content environment is likely to cause the loss of the specific surface area of the catalyst, thereby shortening the service life of the catalyst. . USP4,859,643, USP5,277,880, USP4,880,604 and USP4,977,119 have proposed the bed structure of conical structure bed and different opening ratio, increased the required oxygen amount of upper bed, to adapt to the charcoal burning area entrance In the special case of high catalyst carbon content, although the amount of gas passing through the upper part of the bed has increased, due to the increase in the amount of oxygen required for charcoal burning, the heat released by charcoal burning has also increased, so the high temperature in the upper part of the bed has not changed. To be relieved, only the residence time of the catalyst in the upper part of the bed has been reduced to a certain extent. At the same time, since there is no drying system in the regeneration gas circuit, there is also the problem of high water content in the regeneration cycle gas.

In the regeneration process provided by USP5,034,117 and CN1045411A, the catalyst bed in the charcoal-burning area of the regenerator is divided into two sections, and the catalyst is transported from the upper charcoal-burning section to the lower charcoal-burning section through the material legs, and each section of the bed has the same structural size , the inlet conditions of the regeneration gas of the two beds are different, the inlet temperature of the regeneration gas of the lower bed is higher than that of the upper bed, by supplementing air into the space between the two beds, the two beds have their respective required oxygen content. The regeneration gas passes through the upper charcoal-burning section and the lower charcoal-burning section in turn, and then leads out of the regenerator, mixes with the gas from the outlet of the oxychlorination zone, enters the washing and drying system, and returns to the upper charcoal-burning section of the regenerator through the circulating compressor. Since the drying system is installed in the regeneration cycle loop, the water content in the regeneration cycle gas is low, and due to the use of staged pressurized regeneration, the mass flux of the regeneration gas in the bed is relatively large, so the temperature rise of the bed is relatively low. Segmentation has been significantly reduced.

Contents of invention

The purpose of the present invention is to provide a method for continuous regeneration of hydrocarbon conversion catalysts under the environment of lower temperature and lower water content based on the prior art.

The method provided by the invention is:

The spent catalyst from the moving bed reactor passes through the buffer zone, charcoal burning zone, oxychlorination zone and roasting zone downwards in the regenerator, and the regenerated catalyst leaves the regenerator.

The space enclosed by the outer screen of the charcoal burning area and the inner wall of the regenerator is divided into upper and lower parts. The regeneration gas enters the lower space enclosed by the outer screen and the inner wall of the regenerator, and passes through the lower catalyst bed radially in a centripetal manner. , in the space surrounded by the inner screen, after being fully mixed with the supplementary normal temperature inert gas and dry air, it will pass through the upper catalyst bed radially in a centrifugal manner, and enter the upper part surrounded by the outer screen and the inner wall of the regenerator. space, and then lead out to the regenerator, and return to the regenerator for recycling after heat exchange, alkali washing, water washing, drying, filtration, pressurization and heating.

The method enables the catalyst to be regenerated at a lower temperature and a lower water content environment, and is beneficial to prolonging the service life of the catalyst.

Description of drawings

The accompanying drawing is a schematic flow diagram of the catalyst continuous regeneration method provided by the present invention.

Detailed ways

Method provided by the invention is implemented like this:

From top to bottom, the regenerator is buffer zone, charcoal burning zone, oxychlorination zone and roasting zone.

The raw catalyst from the moving bed reactor enters the regenerator, and after being properly heated by the hot regeneration gas below it in the buffer zone, it enters the charcoal burning area by gravity along multiple material legs, and in the annular space of the charcoal burning area Slowly move down by gravity, contact with regeneration gas and burn all the coke, then enter the oxychlorination zone for chlorine supplementation and redisperse metal components, then enter the roasting zone to remove the moisture on the catalyst and exit the regenerator.

The dry oxygen-containing regeneration gas is introduced from the lower part of the charcoal burning area and enters the lower space surrounded by the outer screen and the inner wall of the regenerator. The inlet temperature is 480-520°C, the inlet oxygen content is 0.2-1.0v%, and the water content of the regeneration gas is 50-200ppmv, passing through the lower catalyst bed radially in a centripetal manner, in the space surrounded by the inner screen, fully mixed with supplementary inert gas at normal temperature and dry air, so that the temperature of the regeneration gas is 400-480 ℃, the inlet oxygen content is 0.2-1.0v%, and then it passes through the upper catalyst bed radially in a centrifugal manner, enters the upper space surrounded by the outer screen and the inner wall of the regenerator, and then leads out of the regenerator to the outlet of the oxychlorination zone After the gas is mixed, it enters the alkali washing and water washing tower to wash off the HCl and CO ₂ in the regeneration gas. After part of the gas is emptied, the remaining gas is dried, filtered and pressurized. A small part of the gas returns to the chlorine oxidation zone, and most of it is heated. After reaching 480-520°C, return to the charcoal burning area of the regenerator for recycling. The operating absolute pressure in the regenerator is 0.3-1.0 MPa.

The regeneration method described in the present invention is applicable to all types of hydrocarbon conversion catalysts, especially to continuous reforming catalysts.

The regeneration method provided by the present invention will be specifically described below in conjunction with the accompanying drawings, but the present invention is not limited thereby. The shape and size of equipment and pipelines are not limited by the drawings, but determined according to specific conditions.

The accompanying drawing is a schematic flow diagram of the catalyst continuous regeneration method provided by the present invention.

The raw catalyst enters the buffer zone 2 in the regenerator through the pipeline 1, and enters the ring-shaped charcoal burning zone 5 through multiple material legs 3, and the catalyst that has completed charcoal burning enters the oxychlorination zone 9 through the material leg 8, and chlorine and metal are regenerated. The dispersed catalyst enters the calcining zone 11 through the dipleg 10, and after the moisture on the catalyst is removed, the catalyst is led out of the regenerator through the pipeline 12.

The space enclosed by the outer screen of the charcoal burning area of the regenerator and the inner wall of the regenerator is divided into 4 and 6 two parts. The regeneration cycle gas is introduced into the regenerator through the pipeline 33 and enters the space 6. The inlet temperature is 480°C, the oxygen content is 0.6v%, and the water content is 100ppmv. The remaining coke then enters the space 7 surrounded by screens in the charcoal burning area, where it is fully mixed with the normal temperature inert gas and dry air supplemented by the pipeline 36. The temperature of the mixed regeneration gas reaches 440°C and the oxygen content reaches 0.5v %, and pass through the upper catalyst bed in a radial direction in a centrifugal manner, and at the same time burn off most of the carbon deposits deposited on the catalyst, and enter the space 4, and lead out from the regenerator through the pipeline 13.

In the regeneration cycle gas circuit, the regeneration gas from the pipeline 13 enters the heat exchanger 14, after heat exchange, it is mixed with the gas in the oxychlorination zone from the pipeline 16 through the pipeline 15, and then enters the water cooler 17, and the regeneration gas after further cooling Enter the alkaline washing water washing tower 19 through the pipeline 18, and the regeneration gas for removing HCl and CO2 is drawn from the pipeline 20, and after being partially emptied by the pipeline 21, it enters the dryer 23 through the pipeline 22, and the regeneration gas for removing moisture enters the filter through the pipeline 24 25. The purified regeneration gas enters the circulation compressor 27 through the pipeline 26, and the pressurized regeneration gas is drawn out from the pipeline 28, wherein a part of the regeneration gas returns to the oxychlorination zone through the pipeline 29, and the other part of the gas passes through the pipeline 34 and is connected with the pipeline 35 After the coming dry air is combined, it is replenished in the space 7 through the pipeline 36, the mainstream gas in the pipeline 28 enters the heat exchanger 14 through the pipeline 30, and after exchanging heat with the regeneration gas in the pipeline 13, enters the heater 32 through the pipeline 31, The heated regeneration gas is introduced into the regenerator through the pipeline 33 and enters the space 6 to complete the cycle of the regeneration gas.

The numbers in the figure are explained as follows: 2 is the buffer zone, 4 is the upper space surrounded by the screen outside the charcoal burning area and the inner wall of the regenerator, 6 is the lower space surrounded by the screen outside the charcoal burning area and the inner wall of the regenerator, and 5 is The catalyst bed in the charcoal burning area, 7 is the space enclosed by the screen in the charcoal burning area, 9 is the oxychlorination area, 11 is the roasting area, 14 is the heat exchanger, 17 is the water cooler, 19 is the alkali washing water washing tower, 23 is a dryer, 25 is a filter, 27 is a circulating compressor, 32 is a heater, 3, 8, and 10 are catalyst feeding legs, 1, 12, 13, 15, 16, 18, 20, 21, 22 , 24, 26, 28, 29, 30, 31, 33, 34, 35, 36 are pipelines.

The advantages of the present invention are:

1. After the space enclosed by the screen outside the charcoal burning area and the inner wall of the regenerator is divided into upper and lower parts, compared with USP4,578,370, USP4,859,643, USP5,277,880, USP4,880,604 and USP4,977,119, the circulation section of the regeneration gas The mass flux of the regeneration gas on the bed section is doubled, and the heat released by the combustion of coke in the bed is constant, and the regeneration gas can pass through the lower temperature before entering the second part of the bed. Inert gas and dry air are used to adjust the inlet temperature, so the temperature rise of the bed is significantly reduced, and at the same time the peak temperature in the bed is reduced, which is beneficial to protect the performance of the catalyst and prolong the service life of the catalyst. Due to the adoption of pressurized regeneration, although the circulation section of the regeneration gas is doubled, the superficial gas velocity of the regeneration gas passing through the bed can be maintained at a low level, so that the catalyst will not stick to the wall in the bed Phenomenon.

2. Directly divide the space surrounded by the screen outside the charcoal burning area and the inner wall of the regenerator into two parts. In addition to reducing the peak temperature of the bed, it is also better than USP5,034,117 and CN1045411A to divide the bed of the charcoal burning area into two sections. The regeneration method saves the catalyst feeding leg between the two beds, reduces the height of the regenerator, simplifies the structure of the regenerator's charcoal burning area, and saves equipment investment.

3. A buffer zone is set on the upper part of the regenerator. The ungenerated catalyst from the reaction system, after passing through the lifting device, first enters the buffer zone in the regenerator, and the ungenerated catalyst in the buffer zone exchanges heat with the hot regeneration gas below. , the temperature of the catalyst is increased to a certain extent, so that the catalyst enters the charcoal burning area at a higher temperature, which improves the charcoal burning efficiency of the upper part of the bed.

4. Drying treatment and other processes are set in the regeneration gas circuit, and the water content in the regeneration gas is very low, so that the charcoal burning process can be completed in an environment with low water content, and the specific surface area loss of the catalyst during the charcoal burning process is small, which is beneficial to Extend catalyst life.

5. An alkali washing system is set in the regeneration cycle gas circuit to remove HCl in the regeneration gas. On the one hand, a part of the regeneration gas can be directly emptied, and on the other hand, the requirements for the materials of the equipment in the regeneration gas circuit are reduced.

Claims (5)

1. A catalyst continuous regeneration method, in which the unborn catalyst from the moving bed reactor passes through the buffer zone, charcoal burning zone, oxychlorination zone and roasting zone downwards in the regenerator, and the regenerated catalyst leaves the regenerator, its characteristics The regeneration gas first enters the lower space surrounded by the outer screen and the inner wall of the regenerator, and after passing through the lower catalyst bed in a centripetal manner, in the space surrounded by the inner screen, it is mixed with the supplementary normal temperature inert gas and dry air. After mixing, it passes through the upper catalyst bed in a centrifugal manner in the radial direction, and enters the upper space surrounded by the outer screen and the inner wall of the regenerator, and then leads out of the regenerator, and undergoes heat exchange, alkali washing, water washing, drying, filtering, After pressurization and heating, it returns to the charcoal burning area of the regenerator for recycling. 2. The method according to claim 1, characterized in that the temperature of the regeneration gas entering the lower catalyst bed is 480-520°C. 3. The method according to claim 1, characterized in that the temperature of the regeneration gas entering the upper catalyst bed is 400-480°C. 4. The method according to claim 1, characterized in that the inlet oxygen content of the regeneration gas entering the lower catalyst bed and the upper catalyst bed is both 0.2-1.0v%. 5. A process according to claim 1, characterized in that the water content of the regeneration gas entering the lower catalyst bed is 50-200 ppmv.