CN103666531B - A kind of catalytic cracking unit start-up method - Google Patents

Abstract

A kind of catalytic cracking unit start-up method, it is made to heat up the fluidizing medium of heat injection revivifier and reactor, close the valve between revivifier and reactor, and loaded by live catalyst with inject at such a temperature can spontaneous combustion contacting containing the combustion oil of metal organic acid salt and water vapor in revivifier, and improve the pressure of revivifier; Stop injecting water vapor and combustion oil after the activity decrease 10%-50% of revivifier inner catalyst, recover regenerator pressure, open the valve on regenerated catalyst line, by catalyst transport to reactor; Catalyzer in reactor enters in settling vessel and carries out gas solid separation, and isolated catalyzer is back to revivifier; In reactor, spray into hydrocarbon oil crude material carry out catalytic cracking reaction and obtain reaction product.The method makes full use of existing apparatus condition, the activity of live catalyst can be reduced to fast the level of equilibrium catalyst before oil spout, thus avoid the catalyst replacement link in ordinary method, makes device drop into normal operation within the shorter time.

Description

A method for starting a catalytic cracking unit

technical field

The invention relates to a method for starting a catalytic cracking unit, more specifically, a method for starting a reactor and a regenerator system of an industrial catalytic cracking unit using fresh catalyst.

Background technique

Fluid catalytic cracking (FCC) is the most important heavy oil lightening process in the current oil refining industry. With the gradual increase in the demand for light petroleum products, new catalytic cracking units have been continuously put into operation around the world.

The start-up process of the reactor and regenerator system of the catalytic cracking industrial unit generally follows the following basic steps: firstly, the air is heated in the auxiliary combustion chamber by burning combustible gas and/or liquid, and then injected into the regenerator and the reactor in sequence, so that the temperature of the two devices is raised to 350°C-550°C; then close the valve on the catalyst circulation pipeline between the two devices, and continue to inject hot air into the regenerator, and feed water vapor into the reactor; then inject the catalyst into the regenerator and make the catalyst under the action of hot air Perform single-device fluidization in the regenerator; spray combustion oil into the regenerator at a suitable temperature, so that the catalyst in the regenerator continues to heat up to about 600°C; wait for the catalyst in the regenerator to be fluidized normally and establish a suitable catalyst material Slowly open the valve on the regenerated catalyst delivery pipeline between the regenerator and the reactor, and transfer part of the high-temperature catalyst in the regenerator to the reactor in a fluidized state; A certain amount of catalyst is used to maintain the catalyst level in the regenerator; after the catalyst in the reactor has a certain reserve and is fluidized normally under the action of water vapor, slowly open the catalyst delivery pipeline between the reactor and the regenerator. The valve allows the catalyst in the reactor to return to the regenerator in a fluidized state, and establishes a two-stage circulating fluidization of the catalyst between the regenerator and the reactor; when the temperature, pressure and catalyst storage of the two devices reach the set value Finally, inject hydrocarbon oil feedstock into the reactor for catalytic cracking reaction and obtain products, and complete the start-up process of the catalytic cracking industrial device reactor and regenerator system.

Catalysts used in the start-up process of catalytic cracking industrial units are generally industrial balance catalysts from similar units, and a few units are started with specially developed low-activity start-up catalysts. The reason why fresh catalysts are not used during the start-up process is mainly because the activity of fresh catalysts is very high, and the reaction of hydrocarbon oil raw materials on fresh catalysts will produce a large amount of coke, resulting in a large amount of coke "piling up" on the catalyst, which in turn leads to not working. In most cases, even similar catalytic cracking units have different feedstock properties and product requirements, so the catalysts used in normal operation are not exactly the same. In order to achieve the expected product distribution, no matter which of the above start-up schemes is adopted, the catalyst used in the start-up process must be slowly replaced with a fresh catalyst specially designed for the unit after the unit is running stably.

Compared with the start-up process of using other equipment balance catalysts and low-activity start-up special catalysts, the direct use of fresh running catalysts can avoid the catalyst replacement link, so that the unit can be put into normal operation in a shorter time, thereby saving the refinery during the start-up process. However, the problem that needs to be solved is how to quickly reduce the activity of the fresh catalyst to the level of the equilibrium catalyst before fuel injection.

It is a very mature method to reduce the activity of catalysts by hydrothermal treatment in the laboratory. The research results show that under the normal operating pressure of the catalytic cracking unit, it is usually necessary to treat the fresh catalytic cracking catalyst with 100% steam at a high temperature of 730°C-830°C to obtain a catalyst with an activity similar to that of the equilibrium catalyst. In the start-up stage, the reaction regeneration system of the catalytic cracking industrial unit relies on the heating method of fuel injection to provide the heat required by the system. Due to the limitation of the device material and the temperature tolerance of the catalyst, the temperature of the two units is generally controlled below 700 °C. It can be seen that the catalytic cracking unit cannot reach the temperature conditions required for laboratory hydrothermal treatment during the start-up stage.

CN1124899C discloses a method for circularly polluting and aging catalytic cracking catalysts, which is to inject the hydrocarbon oil raw material dissolved in metal organic compounds into the reactor to contact and react with the regeneration agent, and to separate the oil gas and catalyst after the reaction, and the oil gas is sent to the subsequent separation System, after the reacted catalyst is stripped, aged by steam and flue gas, and regenerated by oxygen-containing gas, it is transported to the reactor for recycling. After the fresh catalyst is treated by this method, its physical and chemical properties are close to the industrial equilibrium catalyst. This method is implemented on small and medium-scale experimental devices, and is not suitable for catalytic cracking industrial devices.

CN101927198A and CN101927199A disclose a treatment method for improving the selectivity of catalytic cracking catalysts. Fresh catalysts are loaded into a dense-phase fluidized bed, contacted with water vapor, and aged in a certain hydrothermal environment to obtain aged catalysts. The aged catalyst is fed into an industrial catalytic cracking unit. This method can make the activity and selectivity distribution of the catalyst in the catalytic cracking unit more uniform, and its implementation requires the operating catalytic cracking unit to provide necessary external conditions, and the catalytic cracking unit in the start-up stage cannot adopt this method.

Contents of the invention

The purpose of the present invention is to propose a method for starting a catalytic cracking unit using a fresh catalyst on the basis of the existing catalytic cracking industrial unit start-up method.

The start-up method of catalytic cracking unit provided by the invention comprises the following steps:

(1) After injecting the hot gas-phase fluidized medium into the regenerator and reactor of the catalytic cracking unit to heat up, close the valves on the regenerated catalyst delivery pipeline and the waiting catalyst delivery pipeline between the regenerator and the reactor, and put the fresh catalyst Put it into the regenerator, so that the catalyst is in a fluidized state in the regenerator;

(2) When the internal temperature of the regenerator rises above 350°C, inject combustion oil that can spontaneously ignite at this temperature and contain metal organic acid salts into the regenerator to contact and burn with fresh catalyst;

(3) Inject steam into the regenerator to contact with the fresh catalyst, and increase the pressure of the regenerator, and treat the fresh catalyst in a fluidized state under pressurized conditions;

(4) When the micro-reaction activity of the catalyst in the regenerator drops by 10%-50%, stop injecting combustion oil and water vapor containing metal organic acid salts, reduce the pressure of the regenerator to a normal level, and then open the regenerated catalyst delivery pipeline The valve is used to transport the catalyst with reduced micro-reaction activity to the reactor through the regenerated catalyst delivery pipeline;

(5) The catalyst in the reactor enters the settler for gas-solid separation under the impetus of another gas-phase fluidized medium, and the separated catalyst enters the waiting catalyst delivery pipeline;

(6) Open the valve on the delivery pipeline of the raw catalyst to return the catalyst to the regenerator, and establish the circulating fluidization of the catalyst between the regenerator and the reactor;

(7) Spray hydrocarbon oil raw materials into the reactor to carry out catalytic cracking reaction and obtain reaction products.

Method provided by the invention is implemented like this:

The hot gas-phase fluidized medium is injected into the bottom of the regenerator of the catalytic cracking unit, and introduced into the reactor through the regenerated catalyst delivery pipeline and the spent catalyst delivery pipeline between the regenerator and the reactor. The fluidizing medium in step (1) is selected from one or more of air, oxygen, combustible gas combusted in air or oxygen, and combustible liquid combusted in air or oxygen.

After the internal temperature of the regenerator and reactor reaches at least 300°C, close the valves on the regenerated catalyst delivery pipeline and the spent catalyst delivery pipeline. The hot gas-phase fluidizing medium continues to be injected into the regenerator, and another gas-phase fluidizing medium is injected at the bottom of the reactor. The fluidized medium in the reactor can be the same as the fluidized medium in the regenerator in step (1), or steam, preferably steam.

Put the fresh catalyst into the regenerator, so that the catalyst is in a fluidized state under the action of the fluidized medium. The catalyst is any catalyst suitable for use in a catalytic cracking unit.

When the internal temperature of the regenerator reaches above 350°C, combustion oil that can spontaneously ignite at this temperature and contain one or more metal organic acid salts can be injected into the regenerator to contact and burn with fresh catalyst. The metal is selected from one or more of iron, nickel, vanadium, calcium, sodium and magnesium. The combustion oil is selected from one or more of the diesel fractions obtained by various processing means, including one or more of straight-run diesel oil, catalytic cracking diesel oil, coked diesel oil, F-T synthetic diesel oil, and hydrogenated diesel oil. kind.

Inject water vapor into the regenerator equipped with fresh catalyst to contact with the fresh catalyst, and increase the pressure of the regenerator. The pressure is 0.5MPa-3.0MPa, preferably 0.5MPa-1.0MPa, and the temperature is 550°C-700°C, preferably 600°C- Treat fresh catalyst in fluidized state at 680°C. The steam is superheated under the pressure of the regenerator, and its molar ratio to the fluidized medium in the regenerator is 0.1-5, preferably 0.2-2. The pressures mentioned in the present invention all refer to absolute pressures.

When the micro-reaction activity of the catalyst in the regenerator drops by 10%-50%, preferably 15%-30%, stop injecting steam, reduce the pressure of the regenerator to a normal level (generally lower than 0.3MPa), and then turn on the regenerated catalyst The valve on the delivery pipeline transports part of the catalyst with reduced activity to the reactor through the regenerated catalyst delivery pipeline. Described catalyst activity adopts ASTM D3907 or its improved method to measure.

The catalyst in the reactor is driven by the gas phase fluidization medium into the settler for gas-solid separation, and the separated catalyst enters the raw catalyst delivery pipeline. Open the valve on the spent catalyst delivery line to return the catalyst to the regenerator, and establish the circulating fluidization of the catalyst between the regenerator and the reactor. Afterwards, the hydrocarbon oil raw material is injected into the reactor to carry out the catalytic cracking reaction and the reaction product is obtained, and the start-up process of the catalytic cracking unit is completed.

The method provided by the invention is suitable for all fluidized reactors, fluidized regenerators and catalytic cracking catalysts. Wherein the fluidized reactor includes but not limited to various forms of risers, various forms of fluidized beds, various forms of delivery lines or a combination thereof, the structure of the fluidized regenerator and the quantity are not limited, and the composition of the catalytic cracking catalyst is not limited.

The beneficial effects of the method provided by the invention are:

The method provided by the invention makes full use of the conditions that can be provided in the start-up stage of the catalytic cracking unit itself, and can be implemented without modifying the interior of the unit, so the normal operation of the catalytic cracking unit will not be affected.

The method provided by the invention can quickly reduce the activity of the fresh catalyst to the level of the equilibrium catalyst before fuel injection, thereby avoiding the catalyst replacement link after the conventional start-up method, and putting the device into normal operation in a shorter time, Thereby saving the cost input of the refinery during the start-up process.

Description of drawings

Fig. 1 is a schematic flow diagram of a method for starting a catalytic cracking unit using fresh catalyst provided by the present invention.

Detailed ways

The method provided by the present invention will be described in detail below in conjunction with the accompanying drawings, but the present invention is not limited thereto.

As shown in Figure 1, the hot gas-phase fluidized medium is injected into the bottom of the regenerator 10 of the catalytic cracking unit through the pipeline 1, and is introduced into the reaction through the regenerated catalyst delivery pipeline 2 and the spent catalyst delivery pipeline 8 between the regenerator 10 and the reactor 6. 6 and settler 7. After the internal temperature of the regenerator 10, the reactor 6 and the settler 7 reaches at least 300° C., the valves 3 and 9 on the regenerated catalyst delivery pipeline 2 and the spent catalyst delivery pipeline 8 are closed. The hot gas-phase fluidizing medium continues to be injected into the regenerator 10 through the pipeline 1, and another gas-phase fluidizing medium is injected into the pipeline 4 at the bottom of the reactor 6. The fresh catalyst is loaded into the regenerator 10, so that the catalyst is in a fluidized state under the action of the fluidized medium. When the internal temperature of the regenerator 10 reaches above 350°C, the combustion oil that can spontaneously ignite at this temperature and contains one or more metal organic acid salts is sprayed into the regenerator 10 from the pipeline 11 to contact with the fresh catalyst and burn . Water vapor is injected into the bottom of the regenerator 10 from the pipeline 12 to contact with the catalyst, and the pressure of the regenerator 10 is increased to 0.5MPa-1.0MPa through the regulating valve 14 on the flue gas pipeline 13, and treated at a temperature of 550°C-700°C Fresh catalyst in fluidized state. The steam is superheated under the pressure of the regenerator 10, and its molar ratio to the fluidized medium in the regenerator is 0.1-5. When the micro-reaction activity of the catalyst in the regenerator drops by 10% to 50%, stop injecting combustion oil and water vapor containing metal organic acid salts, and reduce the pressure of the regenerator 10 to normal through the regulating valve 12 on the flue gas pipeline 11 level, and then open the valve 3 on the regenerated catalyst delivery pipeline 2, and transport the partially deactivated catalyst to the reactor 6 through the regenerated catalyst delivery pipeline 2. The catalyst in the reactor 6 is driven by the gas-phase fluidized medium from the pipeline 4 into the settler 7 for gas-solid separation, and the separated catalyst enters the spent catalyst delivery pipeline 8 . The valve 9 on the spent catalyst delivery line 8 is opened to return the catalyst to the regenerator 10 , establishing a circulating fluidization of the catalyst between the regenerator 10 and the reactor 6 . Afterwards, the hydrocarbon oil raw material is injected into the reactor 6 from the pipeline 5 to carry out the catalytic cracking reaction and the reaction product is obtained, and the start-up process of the catalytic cracking unit is completed.

The method provided by the present invention is further illustrated below by way of examples, but the present invention is not thereby limited in any way.

The catalyst used in the examples is industrially produced by China Petroleum & Chemical Corporation Catalyst Qilu Branch, and the trade name is MMC-2. The catalyst contains ultra-stable Y-type zeolite and ZSP zeolite with an average pore diameter of less than 0.7 nanometers. The main physical and chemical properties of MMC-2 fresh catalyst are shown in Table 1. The metal organic acid salt used is a commercially available product, produced by U.S. Strem Chemicals. The microreaction activity of catalyst in the embodiment all adopts ASTM D3907 method to measure.

Example 1

Example 1 illustrates the effect of metal contamination and hydrothermal treatment of fresh catalysts using the method provided by the present invention.

A pressurized fixed fluidized bed experimental device was used to simulate the conditions in the start-up stage of the catalytic cracking unit regenerator. Put 100 grams of MMC-2 fresh catalyst into the fixed fluidized bed, and at the same time, air is used as the fluidized medium, heated to about 350°C by the preheating furnace, and then passed into the bottom of the fluidized bed. The catalyst in the fixed fluidized bed is heated and stabilized at 650°C by means of electric heating, and straight-run diesel oil dissolved with vanadium naphthenate and having a vanadium content of 20ppm is injected into the bottom of the fixed fluidized bed at a rate of 0.5 kg/hour; After the water is vaporized and superheated to 400°C, it is passed into the bottom of the fluidized bed, and the molar ratio of water vapor to air is 0.5. The pressure of the fixed fluidized bed is controlled at 0.5MPa through the automatic pressure regulating valve at the outlet of the fixed fluidized bed. The catalyst was treated for 24 hours. The main conditions of the treatment and the microreaction activity of the catalyst after treatment are listed in Table 2.

Example 2

Example 2 illustrates the effect of using the method provided by the invention, using different metals and changing the treatment conditions to pollute and hydrothermally treat fresh catalysts.

The basic method of the experiment is the same as in Example 1, except that the metal organic acid salt in straight-run diesel oil is a mixture of iron naphthenate and sodium naphthenate, and the content of iron and sodium in straight-run diesel oil is 30ppm. The pressure of the fixed fluidized bed is controlled at 2.6MPa, the temperature of the catalyst is controlled at 680°C, and the molar ratio of water vapor to air is 3.2. The catalyst was hydrothermally treated under the above conditions for 6 hours. The main conditions of the treatment and the microreaction activity of the catalyst after treatment are listed in Table 2.

Comparative example 1

Comparative Example 1 illustrates the effect of hydrothermal treatment of only fresh catalyst under the same hydrothermal treatment conditions as in Example 1.

The basic method of the experiment is the same as in Example 1, and the main operating conditions and results are listed in Table 2.

Comparative example 2

Comparative Example 2 illustrates the effect of hydrothermally treating only fresh catalyst for a longer period of time under lower pressure conditions compared to Example 1.

The basic method of the experiment and most of the hydrothermal treatment conditions are the same as in Example 1, except that the pressure of the fixed fluidized bed is controlled at 0.3 MPa, and the treatment time is extended to 72 hours. The main operating conditions and results are listed in Table 2.

The experimental result of embodiment 1 and embodiment 2 in table 2 shows, adopt method provided by the invention, under the condition that fresh catalyst can provide under the start-up stage of catalytic cracking unit, only by 24 hours metal pollution and hydrothermal treatment just can The activity is reduced to the level of the equilibrium catalyst, indicating that the industrial catalytic cracking unit can be started with fresh catalyst by adopting the method provided by the invention. Comparing Example 1 with Comparative Example 1 and Comparative Example 2, it can be seen that under the same hydrothermal treatment conditions, the method provided by the invention can significantly accelerate the activity decay rate of the fresh catalyst; The activity of the fresh catalyst cannot be effectively reduced even if the treatment time is greatly extended.

Table 1

Catalyst MMC-2 Zeolite content, weight % Y 16 ZSP 12 physical properties Specific surface, ^m2 /g 258 Pore volume, ^cm3 /g 0.19 Apparent density, g/ ^cm3 0.75 Sieve, wt% 0-20 microns 0.8 0-40 microns 10.4 0-80 microns 70.8 0-110 microns 88.5 0-149 microns 97.8 >149 microns 2.2 microreactive activity 91

Table 2

Claims (13)

1. a catalytic cracking unit start-up method, is characterized in that the method comprises the following steps:

(1) after making it heat up the gas phase fluidization medium of heat injection For Fcc Regenerator and reactor, close the valve on regenerated catalyst line and reclaimable catalyst line of pipes between revivifier and reactor, and live catalyst is loaded in revivifier, make catalyzer be in fluidized state in revivifier;

(2) when the internal temperature of revivifier is elevated to more than 350 DEG C, injecting in revivifier at such a temperature can spontaneous combustion burning containing the combustion oil of metal organic acid salt and contacts fresh catalyst, one or more in described metal chosen from Fe, nickel, vanadium, calcium, sodium, magnesium, described organic acid be selected from carboxylic acid, thionothiolic acid, alcohol acid, ketone acid, sulfonic acid,-sulfinic acid one or more;

(3) water vapor is injected in revivifier and contacts fresh catalyst, and improve the pressure of revivifier, be in the live catalyst of fluidized state under pressure;

(4) after the micro-activity decline 10%-50% of revivifier inner catalyst, stop injecting the combustion oil containing metal organic acid salt and water vapor, regenerator pressure is down to normal level, open the valve on regenerated catalyst line subsequently, the catalyzer after micro-activity being declined is delivered to reactor by regenerated catalyst line;

(5) catalyzer in reactor enters in settling vessel and carries out gas solid separation under the promotion of another strand of gas phase fluidization medium, and isolated catalyzer enters into reclaimable catalyst line of pipes;

(6) open the valve on reclaimable catalyst line of pipes, make catalyzer be back to revivifier, set up ciculation fluidized between revivifier and reactor of catalyzer;

(7) in reactor, spray into hydrocarbon oil crude material carry out catalytic cracking reaction and obtain reaction product.

2. method according to claim 1, is characterized in that step (2) described pressure is 0.5MPa-3.0MPa.

3. method according to claim 2, is characterized in that step (2) described pressure is 0.5MPa-1.0MPa.

4. method according to claim 1, is characterized in that the temperature of revivifier is 550 DEG C-700 DEG C.

5. method according to claim 4, is characterized in that the temperature of revivifier is 600 DEG C-680 DEG C.

6. method according to claim 1, is characterized in that one or more that described carboxylic acid is selected from naphthenic acid, lipid acid, aromatic acid.

7. method according to claim 1, is characterized in that the mol ratio of fluidizing medium in water vapor described in step (2) and revivifier is 0.1-5.

8. method according to claim 7, is characterized in that the mol ratio of fluidizing medium in water vapor described in step (2) and revivifier is 0.2-2.

9. method according to claim 1, is characterized in that the micro-activity decline 15%-30% of step (4) described catalyzer.

10. method according to claim 1, is characterized in that described another strand of fluidizing medium of step (5) is identical with step (1) described fluidizing medium.

11. methods according to claim 1, is characterized in that described another strand of fluidizing medium of step (5) is water vapor.

12. methods according to claim 1, is characterized in that one or more in described metal chosen from Fe, nickel, vanadium, calcium, sodium, magnesium.

13. methods according to claim 1, is characterized in that one or more that described combustion oil is selected from straight-run diesel oil, catalytic cracking diesel oil, coker gas oil, F-T combined diesel oil, hydrogenated diesel oil.