CN110124752A - A kind of process for fixed bed catalyst coke burning regeneration - Google Patents

Abstract

The invention discloses a process method for coking regeneration of a fixed bed catalyst. The regeneration gas is fed into the fixed bed which needs catalyst burnt regeneration, and the air content in the regeneration gas is related to the temperature of the top catalyst bed in the fixed bed. The relationship is as follows: when the temperature of the top catalyst bed is ≥420 and <435°C, the air content is 0-3.0%; when the temperature of the top catalyst bed is ≥435 and <440°C, the air content is 2.0- 5.0%; when the temperature of the top catalyst bed is ≥440 and <450°C, the air content is 3.0‑10.0%; when the temperature of the top catalyst bed is ≥450 and <460°C, the air content is 5.0‑ 20.0%; when the temperature of the top catalyst bed is ≥460°C and <490°C, the air content is 15‑50%. The technical method of the invention shortens the regeneration time of charring, improves the efficiency of regeneration of charring, and effectively utilizes the heat generated by charring.

Description

A kind of technical method for fixed-bed catalyst burnt regeneration

technical field

The invention relates to the field of catalyst regeneration technology, in particular to a fixed-bed reaction technology in which the catalyst needs to be burnt to regenerate due to deactivation due to carbon deposits.

Background technique

At present, there are two ways to regenerate coking of fixed-bed catalysts in the industry: internal regeneration and external regeneration. In the traditional single-stage or multi-stage fixed-bed catalyst coking process, the compressed air heated by the heating furnace enters from the top of the reactor, and the catalyst is charred and regenerated by using the heat generated by the charred regeneration. The catalyst burns continuously from the top until it penetrates the entire bed, and the burn ends after the temperature rise of the bed has no obvious change. Although this regeneration method is simple, it takes a long time to burn in actual production, consumes a lot of energy, and there is a risk of catalyst bed overheating.

The existing methods for burning and regenerating catalysts focus on how to reduce local overheating and regeneration energy consumption. USP4780195 suggests adding a certain amount of water in the firing atmosphere to prevent sintering. USP4202865 adopts the method for intermittent oxygen injection to prevent catalyst overheating. USP5037785 uses laser irradiation to decoke the catalyst under oxygen-containing gas. CN102107170 is equipped with a multi-stage simultaneous coking device, and a regenerated circulating gas compressor is added on the basis of the conventional coking process, and the recycled regenerated circulating gas can shorten the coking time and reduce the energy consumption of the device. In the process of CN 102294276, the high-temperature charred medium passing through the heating furnace enters from the top of the reactor, and the high-temperature charred flue gas coming out from the first stage catalyst bed is compared with the temperature from the interstage distributor before entering the second stage catalyst bed layer. The low-burning medium is mixed, and then enters the second stage of the catalyst bed, and so on, until the last stage of the catalyst bed high-temperature charred flue gas exits the reactor.

Molecular sieve catalysts have a short scorch time and high scorch strength in the temperature range of 500°C-600°C. However, due to the limitation of the high temperature resistance of the internal components of the fixed bed reactor, the regeneration temperature must be lower than 510°C. During the regeneration process of the catalyst, if the temperature is too low, the carbon deposits on the surface of the catalyst or in the pores cannot be burned, and the regeneration effect cannot be achieved; if the temperature is too high, the catalyst will be sintered and the catalyst will be permanently deactivated.

Therefore, there is an urgent need to provide a catalyst burnt regeneration method that can effectively utilize the heat generated by the burnt catalyst and improve the strength of the catalyst burnt regeneration.

Contents of the invention

In view of this, the present invention provides a process for coke regeneration of fixed-bed catalysts, which shortens the time of coke regeneration, improves the efficiency of coke regeneration, and effectively utilizes the heat generated by coke.

To achieve the above object, the present invention adopts the following technical solutions:

A method for regeneration of coke catalyst in a fixed bed, in which a regeneration gas is introduced into the fixed bed that requires catalyst coke regeneration, so as to regenerate the catalyst in the catalyst bed layer in the fixed bed, said The temperature relationship between the content of air in the regeneration gas and the top catalyst bed in the fixed bed is as follows:

When the temperature of the top catalyst bed is ≥420°C and <435°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 0-3.0%, preferably 1-2.5%;

When the temperature of the top catalyst bed is ≥435°C and <440°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 2.0-5.0%, preferably 2.5-3.5%;

When the temperature of the top catalyst bed is ≥440°C and <450°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 3.0-10.0%, preferably 3.5-7.0%;

When the temperature of the top catalyst bed is ≥450°C and <460°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 5.0-20.0%, preferably 7.0-18%;

When the temperature of the top catalyst bed is ≥460°C and <490°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 15-50%, preferably 20-50%.

The technical method of the present invention utilizes fixed-bed reactors to carry out in-situ charred regeneration, and passes regeneration gas into the fixed bed to perform charring to remove carbon deposits on the surface of the catalyst in the bed. The total amount of regeneration gas supplied from outside the fixed bed and into the fixed bed remains constant (that is, the sum of nitrogen and air), and the gases (air and nitrogen) that make up the regeneration gas are in accordance with the top catalyst bed before entering the fixed bed. The real-time temperature of the layer is adjusted to the above ratio (volume ratio).

In a specific embodiment of the process method of the present invention, the regeneration gas is all fed through the top inlet of the fixed bed, and the catalyst bed in the fixed bed is charred and regenerated. In another embodiment of the present invention, the regeneration gas is fed through the top inlet of the fixed bed and the side line of the fixed bed respectively. In the process of coking and regenerating the catalyst in the catalyst bed layer in the fixed bed, the total gas volume of the regeneration gas introduced remains constant, and the gas volume of the regeneration gas introduced through the top of the fixed bed accounts for the total amount of the regeneration gas Most of the regeneration gas is introduced from the top of the fixed bed reactor and burns the top catalyst bed, using the heat of this part of the catalyst bed to burn the carbon deposits in the second catalyst bed Heat is provided to bring the second layer of catalyst to a temperature for char regeneration. When the regeneration gas (including the top regeneration gas and the side feed regeneration gas) is passed into the second layer of catalyst, the heat generated by the burning of carbon deposits is used to make the third layer of catalyst reach the temperature of burnt regeneration, and so on. The side regeneration gas can regulate the temperature of the catalyst bed within a certain range. In some preferred embodiments, the amount of regeneration gas introduced through the top of the fixed bed accounts for 52-100% of the total amount of regeneration gas, preferably 60-70%, such as 66%, 68%. Simultaneously, the sum of the gas volume of the regeneration gas supplied to other catalyst beds of the fixed bed (including the catalyst beds of the second layer and below) by the side line of the fixed bed accounts for 0-48% of the total gas volume of the regeneration gas, Preferably 35-45%, such as 35%, 40%, 42%.

In some preferred embodiments, as understood by those skilled in the art, the fixed bed also includes many side lines, which are used to transport the regeneration gas introduced from the outside of the fixed bed to each catalyst bed respectively, so as to achieve the effect of layered roasting, It prevents the heat enrichment during the regeneration process of the catalyst, reduces the hot spot temperature of the catalyst bed during the burning process, and prevents catalyst sintering caused by temperature runaway during the burning regeneration process. The "catalyst bed temperature" mentioned in the process of the present invention refers to the temperature at the entrance of the catalyst bed of the fixed bed, and in the present invention, it is named in turn according to the order direction from the top of the fixed bed to the lower part. The top catalyst bed, the second catalyst bed, the third catalyst bed, etc.

The present invention relates to a method for coke regeneration in a fixed-bed multi-bed catalyst. In some specific embodiments, the number of layers of the fixed-bed catalyst bed is 6-8. As is well known to those skilled in the art, the loading capacity of catalysts in the catalyst beds of various levels in the fixed bed is different, and the gas volume of the regeneration gas passed into the catalyst beds of each layer in the fixed bed is also different, in some of the present invention In the specific embodiment, the number of layers of the catalyst bed in the fixed bed is 6 layers, and the relationship between the gas volume of the regeneration gas introduced by the side line of the fixed bed and the total gas volume of the regeneration gas is as follows:

The amount of regeneration gas introduced into the second layer of catalyst bed in the fixed bed through the side line accounts for 4.5-7.5% of the total amount of regeneration gas, preferably 5-7.2%;

The amount of regeneration gas introduced into the third catalyst bed in the fixed bed through the side line accounts for 5.0-8.0% of the total amount of regeneration gas, preferably 5.3-7.6%;

The amount of regeneration gas introduced into the fourth layer of catalyst bed in the fixed bed through the side line accounts for 5.5-8.5% of the total amount of regeneration gas, preferably 5-8.2%;

The amount of regeneration gas introduced into the fifth catalyst bed in the fixed bed through the side line accounts for 7.5-11.3% of the total amount of regeneration gas, preferably 6-11%;

The amount of the regeneration gas fed to the sixth catalyst bed in the fixed bed through the side line accounts for 10-14.5% of the total amount of the regeneration gas, preferably 10.5-14.0%.

In some specific implementations, at the initial stage of coke regeneration, nitrogen gas heated by a heating furnace can be introduced into the fixed bed to remove impurities attached to the deactivated catalyst in the catalyst bed, and the catalyst bed is deactivated. heat up. When the temperature of the top catalyst bed reaches the above temperature range, the air content in the regeneration gas is adjusted. In the early stage of coke regeneration, there are more carbon deposits in the catalyst bed, and the heat is released under oxygen-containing conditions, so only a small amount of air is needed in the regeneration gas. With the prolongation of the regeneration time, the amount of carbon deposits in the catalyst is continuously reduced, the proportion of air in the regeneration gas is gradually increased, and the temperature of the catalytic bed is increased within a certain range, so that the carbon deposits in the catalyst are gradually burned.

In the process method of the present invention, the temperature of the charred regeneration is controlled to be ≥420°C and <490°C, preferably ≥425°C and <480°C, for example, 470°C, 475°C; The fixed bed is heated by a heater outside the fixed bed before, so as to ensure the regeneration effect of the catalyst. In some specific embodiments, the regeneration gas is heated to ≥420°C and <470°C, preferably ≥440°C, And <460°C, for example, 445°C, 455°C.

The process method provided by the present invention is applied to the burnt regeneration of the used catalyst of methanol to propylene; The used catalyst of described methanol to propylene is preferably selected from HZSM-5 molecular sieve catalyst, alkaline earth metal supported REZSM-5 molecular sieve catalyst (loaded on such Alkaline earth metals in the catalyst include such as, magnesium, calcium, strontium, barium, radium), rare earth load REZSM-5 molecular sieve catalyst, phosphorus load ZSM-5 molecular sieve catalyst or boron load ZSM-5 molecular sieve catalyst, the catalyst used in the present invention can adopt Any of the above-mentioned types are commercially available.

Adopt above-mentioned technical scheme, have following technical effect:

In the charred regeneration process of the present invention, the temperature of the top catalyst bed in the fixed bed is used to control the air content in the regeneration gas passed into the fixed bed, effectively controlling the relaxation of the charred regeneration process and avoiding the catalyst bed The phenomenon of layer overheating prevents the sintering of the catalyst caused by overheating during the burning process.

Simultaneously, the burnt regeneration process of the present invention is beneficial to utilize the heat generated by burnt, and improves the burnt regeneration efficiency.

Description of drawings

Fig. 1 is the weight loss curve of embodiment 1 catalyst burnt regeneration process;

Fig. 2 is the weight loss curve of embodiment 2 catalyst burnt regeneration process;

Fig. 3 is the weight loss curve of the coke regeneration process of the catalyst of Comparative Example 1.

Detailed ways

The present invention will be described in detail below, but the present invention is not limited thereto.

In each of the following examples of the present invention, what adopt is the fixed-bed reactor of methanol to propylene with six layers of catalyst beds, which is packed with commercially available HZSM-5 molecular sieve catalyst;

The methanol-to-propylene fixed-bed reactor is used to produce propylene from methanol under the following conditions: methanol feed space velocity is 0.73h ^-1 , m _{(water vapor)} /m _(methanol) is 0.6, m _{(cycle hydrocarbon)} /m _{( Methanol)} is 1.0, the inlet temperature of the fixed bed reactor is 427°C, the outlet temperature is 478°C, and the pressure inside the reactor is 0.23Mpa. When the overall conversion of the DME/MeOH feed is below 90%, the following regeneration is performed as follows.

Example 1

Regenerate the catalyst bed in the methanol-to-propylene fixed-bed reactor: heat the regeneration gas to 433°C in a heating furnace outside the fixed-bed reactor, and then pass it into the fixed-bed from the top inlet of the fixed-bed reactor, The total gas volume of regeneration gas is 83000Nm ³ /h.

The temperature of the top catalyst bed in the fixed bed and the air content in the regeneration gas introduced are shown in Table 1:

Table 1

Note: The running time in the table refers to the start of timing when the regeneration gas is introduced into the fixed bed, and the same reasoning follows.

The coke content in the regenerated catalyst was tested by a synchronous thermal analyzer. The weight loss curve of the catalyst is shown in Figure 1, and the coke content of the catalyst was finally measured to be 36.38%.

Example 2

Regenerate the catalyst bed in the methanol-to-propylene fixed-bed reactor: heat the regeneration gas to 430°C in a heating furnace outside the fixed-bed reactor, and then pass it through the top and side lines of the fixed-bed reactor to the fixed-bed The total gas volume of regeneration gas is 84300Nm ³ /h.

The temperature of the top catalyst bed in the fixed bed and the air content in the regenerated gas introduced are as shown in Table 2:

Table 2

Note: The ratio of regeneration gas in the table refers to the volume ratio of the amount of regeneration gas supplied to the catalyst bed to the total amount of regeneration gas.

After the catalyst in Example 2 was regenerated by burning, the coke content in the catalyst was tested by a synchronous thermal analyzer. The weight loss curve of the catalyst is shown in FIG.

comparative example

Regenerate the catalyst bed in the methanol-to-propylene fixed-bed reactor: heat the regeneration gas to 430°C in a heating furnace outside the fixed-bed reactor, and then pass it through the top and side lines of the fixed-bed reactor to the fixed-bed The total gas volume of regeneration gas is 84300Nm ³ /h.

The temperature of the top catalyst bed in the fixed bed and the air content in the regeneration gas introduced are shown in Table 3:

table 3

Above-mentioned comparative example and embodiment 2 adopt the regenerating gas of the same total amount of gas to burn the catalyst bed in the methanol-to-propylene fixed-bed reactor, and the regeneration time of the catalyst in the comparative example is 120 hours, which is the same as that in embodiment 2. The burnt regeneration process only takes 72 hours. Compared with it, the required regeneration time is longer and the energy consumption is higher. At the same time, the coke content in the catalyst after the burnt regeneration is tested by a synchronous thermal analyzer. The weight loss curve of the catalyst is shown in Figure 3 As shown, the final measured carbon content of the catalyst is 27.55%.

From the data in above-mentioned table 1-3 as can be known, by the present invention technology regeneration process in the catalyzer consumption coke amount is more, the residual coke on the catalyzer is less, and has effectively utilized the heat that scorching produces, improves scorching regeneration efficiency.

Claims (9)

1. A process for catalyst burnt regeneration of a fixed bed is characterized in that, in the fixed bed that needs to carry out catalyst burnt regeneration, feed regeneration gas, to carry out the catalyst in the catalyst bed layer in the fixed bed Charred regeneration, the content of air in the regeneration gas and the temperature relationship of the top catalyst bed in the fixed bed are as follows: When the temperature of the top catalyst bed is ≥420°C and <435°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 0-3.0%; When the temperature of the top catalyst bed is ≥435°C and <440°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 2.0-5.0%; When the temperature of the top catalyst bed is ≥440°C and <450°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 3.0-10.0%; When the temperature of the top catalyst bed is ≥450°C and <460°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 5.0-20.0%; When the temperature of the top catalyst bed is ≥460°C and <490°C, the volume content of air in the regeneration gas passed into the fixed bed is controlled to be 15-50%. 2. The process according to claim 1, characterized in that the regeneration gas is introduced through the top inlet of the fixed bed. 3. The process according to claim 1, characterized in that, the regeneration gas is fed through the top inlet of the fixed bed and the side line of the fixed bed. 4. The process according to any one of claims 1-3, characterized in that, the number of layers of the catalyst bed of the fixed bed is 6-8 layers. 5. process method according to claim 4, is characterized in that, in the process that the catalyst in the catalyst bed layer in described fixed bed is carried out burnt regeneration, the total gas volume of the regeneration gas that feeds remains constant, The amount of the regeneration gas introduced through the top inlet of the fixed bed accounts for 52-100% of the total amount of the regeneration gas, preferably 60-70%. 6. The process according to claim 5, characterized in that, the number of layers of the catalyst bed in the fixed bed is 6 layers, and the gas volume of the regeneration gas introduced by the side line of the fixed bed is equal to the total amount of the regeneration gas. The volume relationship is as follows: The amount of regeneration gas introduced into the second layer of catalyst bed in the fixed bed through the side line accounts for 4.5-7.5% of the total amount of regeneration gas, preferably 5-7.2%; The amount of regeneration gas introduced into the third catalyst bed in the fixed bed through the side line accounts for 5.0-8.0% of the total amount of regeneration gas, preferably 5.3-7.6%; The amount of regeneration gas introduced into the fourth layer of catalyst bed in the fixed bed through the side line accounts for 5.5-8.5% of the total amount of regeneration gas, preferably 5-8.2%; The amount of regeneration gas introduced into the fifth catalyst bed in the fixed bed through the side line accounts for 7.5-11.3% of the total amount of regeneration gas, preferably 6-11%; The amount of the regeneration gas fed to the sixth catalyst bed in the fixed bed through the side line accounts for 10-14.5% of the total amount of the regeneration gas, preferably 10.5-14.0%. 7. The process according to any one of claims 1-6, characterized in that the temperature at which the catalyst bed in the fixed bed undergoes burnt regeneration is ≥420°C and <490°C, preferably ≥425°C , and <480°C. 8. The process according to claim 6, characterized in that the temperature of the regeneration gas fed into the fixed bed is ≥420°C and <470°C, preferably ≥440°C and <460°C. 9. according to the process described in any one in claim 1-8, it is characterized in that, described process is applied to the charred regeneration of the used catalyst of methanol to propylene; The catalyst used for methanol-to-propylene is preferably selected from HZSM-5 molecular sieve catalyst, alkaline earth metal supported REZSM-5 molecular sieve catalyst, rare earth supported REZSM-5 molecular sieve catalyst, phosphorus supported ZSM-5 molecular sieve catalyst or boron supported ZSM-5 molecular sieve catalyst.