CN112745936B

CN112745936B - Desulfurization method for catalytic cracking light product, method and device for producing low-sulfur light oil product through catalytic cracking

Info

Publication number: CN112745936B
Application number: CN201911049610.XA
Authority: CN
Inventors: 毛安国; 王文寿; 刘宪龙; 徐莉; 刘玉良
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2019-10-31
Filing date: 2019-10-31
Publication date: 2022-10-21
Anticipated expiration: 2039-10-31
Also published as: CN112745936A

Abstract

A catalytic cracking light product desulfurization method and device, (1) crude gasoline from a fractionating tower of a catalytic cracking device is introduced into a first desulfurization reactor, contacts with a desulfurization adsorbent under the hydrogen condition for desulfurization and flows upwards; one part of the sulfur-carrying adsorbent separated by gas-solid separation enters the upper part of the second desulfurization reactor, and the other part of the sulfur-carrying adsorbent and the oxygen-containing gas are roasted and regenerated in the adsorbent regenerator for cyclic use; the reaction oil gas obtained by separation is desulfurized crude gasoline; (2) The desulfurization adsorbent in the second desulfurization reactor is in countercurrent contact with rich gas for adsorption desulfurization reaction, and the desulfurization adsorbent returns to the first desulfurization reactor after the reaction; (3) And respectively sending the desulfurized rich gas and the desulfurized crude gasoline to an absorption stabilizing unit for further separation to obtain desulfurized dry gas, liquefied gas and stabilized gasoline. The method provided by the invention is suitable for treating rich gas and crude gasoline obtained by a catalytic cracking fractionating tower, and the obtained refined gasoline has high yield and less octane value loss.

Description

Desulfurization method for catalytic cracking light product, method and device for producing low-sulfur light oil product through catalytic cracking

Technical Field

The invention belongs to the field of petrochemical industry, relates to a hydrocarbon oil desulfurization method, and more particularly relates to a catalytic cracking rich gas and crude gasoline desulfurization and separation method.

Background

The catalytic cracking unit of an oil refinery is a main source of low-carbon olefin, liquefied gas and gasoline, and in the existing catalytic cracking process flow, components such as rich gas, crude gasoline, light diesel oil, heavy diesel oil, oil slurry and the like can be obtained after the reaction product of the catalytic cracking unit is fractionated. The rich gas passes through the absorption desorption tower and the reabsorption tower to obtain a dry gas product, and the dry gas can be used as refinery fuel gas after being desulfurized. The crude gasoline can be separated by an absorption stabilizer to obtain liquefied gas and catalytic cracking stable gasoline, the catalytic cracking gasoline is desulfurized and then leaves a factory as a product, the liquefied gas can be desulfurized and then leaves a factory as a product, and meanwhile, the liquefied gas can be used as a raw material to provide high-value components such as propylene, butylene and the like for other devices.

Both dry gas, liquefied gas and catalytically cracked gasoline must be desulfurized under increasingly stringent environmental regulations and downstream process requirements. At present, the process of desulfurization of dry gas, liquefied gas and catalytic gasoline is respectively carried out under the limitation of desulfurization process, and the process of alkaline washing desulfurization and the like commonly used for the dry gas and the liquefied gas can generate a large amount of waste liquid, waste residue and the like again. In addition, the existing liquefied gas desulfurization process has the problem that the desulfurization depth is insufficient, so that the sulfur content is too high, and further application of the liquefied gas is limited.

The adsorption desulfurization method of hydrocarbon oil is a technological process for making adsorption desulfurization of light hydrocarbon oil under the condition of hydrogenation, and can be used for continuously regenerating sulfur-containing adsorbent. The method has the characteristics of high desulfurization depth, low hydrogen consumption and the like, and can produce fuel oil with the sulfur content of less than 30 micrograms/gram. The process is used for treating the catalytic cracking stable gasoline desulfurization, and has the problems of low catalytic cracking product liquid yield and large gasoline octane number loss.

Disclosure of Invention

The invention aims to solve the technical problems of low yield and high octane value loss of stable gasoline produced by a catalytic cracking device, and provides a method for desulfurizing and separating catalytic cracking light products to obtain desulfurized dry gas, desulfurized liquefied gas and catalytic cracking stable gasoline.

The invention also provides a device for desulfurizing the catalytic cracking light product.

The invention provides a method for desulfurizing and separating catalytic cracking light products, which comprises the following steps:

(1) Introducing crude gasoline from a catalytic cracking fractionating tower into a first desulfurization reactor from the bottom, and desulfurizing the crude gasoline in contact with a desulfurization adsorbent under the hydrogen condition while flowing upwards in a concurrent flow manner; gas-solid separation is carried out on the reaction oil gas and the desulfurization adsorbent in a settling zone at the upper part of the first desulfurization reactor, one part of the sulfur-loaded adsorbent enters the upper part of the second desulfurization reactor from the top of an adsorbent bed layer through a slide valve, the other part of the sulfur-loaded adsorbent is roasted and regenerated in an adsorbent regenerator, and the regenerated desulfurization adsorbent is reduced and then returns to the bottom of the first desulfurization reactor for recycling;

(2) The rich gas from the catalytic cracking fractionating tower enters a second desulfurization reactor from the bottom, and is in countercurrent contact with a desulfurization adsorbent to carry out adsorption desulfurization reaction, and the desulfurization adsorbent returns to the first desulfurization reactor from the bottom of the second desulfurization reactor after the reaction;

(3) And respectively sending the desulfurized raw gasoline obtained from the top of the first desulfurization reactor and the desulfurized rich gas obtained from the top of the second desulfurization reactor to an absorption stabilizing unit for further separation to obtain desulfurized dry gas, liquefied gas and stabilized gasoline.

A method for producing low-sulfur light oil products by catalytic cracking comprises introducing catalytic cracking raw materials into a riser reactor, contacting with a catalytic cracking catalyst, reacting under the catalytic cracking reaction condition, carrying out gas-solid separation on the top of the riser reactor, introducing the obtained reaction oil gas into a catalytic cracking fractionating tower, and fractionating to obtain rich gas, crude gasoline, light diesel oil, diesel oil and oil slurry; the separated catalytic cracking catalyst is regenerated and then returned to the riser reactor for recycling; and introducing the crude gasoline and the rich gas into a first desulfurization reactor and a second desulfurization reactor respectively, and performing adsorption desulfurization and absorption stabilization separation by adopting the catalytic cracking light product desulfurization method to obtain desulfurized dry gas, desulfurized liquefied gas and stabilized gasoline.

A catalytic cracking light product desulphurization unit comprises an adsorption desulphurization unit and an absorption stabilization unit which are sequentially communicated; the adsorption desulfurization unit comprises a first desulfurization reactor, a reactor receiver, a lock hopper, a regenerator feeding tank and an adsorbent regenerator which are sequentially communicated, wherein the adsorbent regenerator is sequentially communicated with the regenerator receiver, the lock hopper, an adsorbent reducer and the bottom of the first desulfurization reactor, the upper part of the first desulfurization reactor is communicated with the upper part of a second desulfurization reactor, and the bottom of the second desulfurization reactor is communicated with the bottom of the first desulfurization reactor; the absorption stabilizing unit consists of an absorption tower, a desorption tower, a reabsorption tower and a stabilizing tower which are communicated in sequence.

Compared with the prior art, the catalytic cracking light product desulfurization method and the catalytic cracking light product desulfurization device provided by the invention have the beneficial effects that:

according to the catalytic cracking light product desulfurization method provided by the invention, the catalytic cracking rich gas and the crude gasoline are firstly subjected to adsorption desulfurization and then are stably absorbed, so that the loss of the gasoline yield caused by the traditional method can be reduced to the maximum extent. In the adsorption desulfurization reactor, hydrogen in the rich gas is used as reaction hydrogen to participate in the reaction, so that the hydrogen consumption is saved. The sulfur content of the desulfurized dry gas, liquefied gas and stable gasoline obtained by adsorbing and desulfurizing the rich gas and the crude gasoline and passing through a fractionation-absorption-stabilization system can reach below 10ppm, even below 1 ppm. The rich gas and the crude gasoline are subjected to adsorption desulfurization, so that the loss of low-carbon olefins in the rich gas is less.

The method for desulfurizing the catalytic cracking light product saves devices such as dry gas, liquefied gas desulfurization and the like required by the traditional refinery, and does not have the problems of waste liquid, waste residue and the like possibly generated by the traditional desulfurization method.

The catalytic cracking light product desulfurization method provided by the invention adopts two desulfurization reactors, wherein the crude gasoline in the first desulfurization reactor and the desulfurization adsorbent flow upwards in a parallel flow manner, the reaction time is long, and the thiophene sulfides which are difficult to remove are completely removed; the rich gas in the second desulfurization reactor is in countercurrent contact with the desulfurization adsorbent for adsorption desulfurization, so that the contact time of olefin in the rich gas and the adsorbent can be reduced, and the saturation of low-carbon olefin is reduced.

Drawings

FIG. 1 is a schematic flow diagram of an adsorption desulfurization unit.

FIG. 2 is a schematic flow diagram of an absorption stabilization unit.

Wherein:

2-first desulfurization reactor, 8-second desulfurization reactor, 5-reactor receiver, 13-lock hopper, 16-regenerator feed tank, 19-sorbent regenerator, 22-regenerator receiver, 25-sorbent reducer, 1, 3, 4, 6, 7, 9, 10, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24, 26-pipeline; 34-absorption tower, 35-desorption tower, 36-reabsorption tower, 37-stabilization tower, and 29, 30, 31, 32, 33, 38, 40, 41 and 42-pipelines.

Detailed Description

In the following detailed description of the embodiments of the present invention, reference in the specification to the "bottom" of the container means from the bottom to the top of the container from 0 to 10%, reference to the "lower" of the container means from the bottom to the top of the container from 0 to 50%, reference to the "upper" of the container means from the bottom to the top of the container from 50 to 100%, and reference to the "top" of the container means from the bottom to the top of the container from 90 to 100%.

(1) Introducing the crude gasoline from the catalytic cracking fractionating tower into a first desulfurization reactor from the bottom, and desulfurizing the crude gasoline by contacting with a desulfurization adsorbent under the hydrogen condition while flowing upwards in a concurrent manner; gas-solid separation is carried out on the reaction oil gas and the desulfurization adsorbent in a settling zone at the upper part of the first desulfurization reactor, one part of the sulfur-loaded adsorbent enters the upper part of the second desulfurization reactor from the top of the adsorbent bed through a slide valve, the other part of the sulfur-loaded adsorbent is roasted and regenerated in an adsorbent regenerator, and the regenerated desulfurization adsorbent is reduced and then returns to the bottom of the first desulfurization reactor for recycling;

In the method provided by the invention, desulfurized rich gas enters an absorption tower from the bottom and is in contact absorption with desulfurized crude gasoline introduced from the top of the absorption tower, material flow at the top of the absorption tower enters a reabsorption tower from the bottom and is in countercurrent contact absorption with light diesel oil from a catalytic cracking fractionating tower, desulfurized dry gas is obtained from the top of the reabsorption tower, and the light diesel oil obtained from the bottom of the reabsorption tower returns to the catalytic cracking fractionating tower; the bottom product of the absorption tower passes through a desorption tower and is sent to a stabilization tower, the product is fractionated in the stabilization tower to obtain desulfurized liquefied gas and stabilized gasoline, and the gas at the top of the desorption tower returns to the absorption tower.

Specifically, the mixture of the crude gasoline and the hydrogen donor from the fractionating tower of the catalytic cracking unit is preheated to 100 to 500 ℃, preferably 200 to 450 ℃. The heated crude gasoline is used as a raw material of a first desulfurization reactor, the heated crude gasoline enters the reactor from the bottom of the first fluidized bed desulfurization reactor, a desulfurization adsorbent is conveyed into the first desulfurization reactor from the bottom, a reaction oil gas is contacted with the desulfurization adsorbent to carry out adsorption desulfurization reaction, meanwhile, a reaction material flow flows upwards in a concurrent flow manner, the reaction oil gas and the desulfurization adsorbent are subjected to gas-solid separation in a settling zone at the upper part of the first desulfurization reactor, one part of the separated sulfur-carrying adsorbent is controlled by a slide valve to enter a second desulfurization reactor, the other part of the sulfur-carrying adsorbent and oxygen-containing gas are roasted and regenerated in an adsorbent regenerator, and the regenerated desulfurization adsorbent is reduced and then returns to the bottom of the first desulfurization reactor for recycling. The reaction oil gas obtained by separation is a mixture of desulfurized crude gasoline and hydrogen and is sent to a subsequent absorption stabilizing unit for further separation.

And conveying the crude gasoline or the mixture of the crude gasoline and the hydrogen donor into the first desulfurization reactor from the bottom, wherein the mixture of the crude gasoline and the hydrogen donor is uniformly distributed in the reactor through a feeding distribution disc and is in good contact with a desulfurization adsorbent in the reactor.

And (3) carrying out gas-solid separation on the reaction oil gas and the desulfurization adsorbent in a settling zone with an enlarged pipe diameter at the upper part of the first desulfurization reactor, wherein gas-solid separation equipment such as a cyclone separator or a filter is also arranged in the settling zone.

The desulfurization adsorbent is introduced into the second fluidized bed reactor from the upper part, and contacts with the rich gas or the mixture of the rich gas and the hydrogen donor which enters from the bottom of the reactor and is preheated to the required temperature in a countercurrent mode to carry out desulfurization reaction, the reaction oil gas and the desulfurization adsorbent are subjected to gas-solid separation in a settling zone at the upper part of the second desulfurization reactor, and gas-solid separation equipment such as a filter and the like is preferably arranged in the settling zone. The reaction oil gas obtained by separation is desulfurized rich gas and enters an absorption stabilizing system for further separation.

Preferably, the position from bottom to top of the first desulfurization reactor from 50% to 90% is communicated with the position from bottom to top of the second desulfurization reactor from 80% to 90%.

Preferably, the feeding gas velocity of the first desulfurization reactor is 0.25 to 10m/s, and the feeding gas velocity of the second desulfurization reactor is 0.05 to 1.5m/s; the first desulfurization reactor and the second desulfurization reactor are fluidized bed reactors.

In the method provided by the invention, the sulfur content of the rich gas and the crude gasoline from the catalytic cracking fractionating tower is 30 to 50000 micrograms/g, and preferably more than 50 micrograms/g. The rich gas may contain other components such as nitrogen, carbon dioxide, hydrogen and hydrogen sulfide.

The hydrogen donor is selected from one or a mixture of more than two of hydrogen, hydrogen-containing gas and hydrogen donor. The hydrogen gas is hydrogen gas with various purities, the hydrogen-containing gas is preferably one or a mixture of two or more of dry gas produced by the method, catalytic cracking (FCC) dry gas, coking dry gas and thermal cracking dry gas, the hydrogen volume content is preferably more than 30%, and the hydrogen donor is one or a mixture of more than one selected from tetrahydronaphthalene, decahydronaphthalene and indane.

The operating conditions of the first desulfurization reactor are that the temperature is 200-550 ℃, preferably 300-500 ℃, the absolute pressure is 0.5-5 MPa, preferably 1.0-3.5 MPa, and the weight hourly space velocity of the oil gas raw material is 0.1-100 h ^-1 Preferably 1 to 10 hours ^-1 . Preferably, the crude gasoline is contacted with a desulfurization adsorbent in a hydrogen atmosphere to carry out adsorption desulfurization reaction, wherein the molar ratio of hydrogen to oil is 0.01-1000, and preferably 0.05-500.

Heating the rich gas or the mixture of the rich gas and the hydrogen donor to 100 to 500 ℃, preferably 250 to 450 ℃. The heated rich gas or rich gas and hydrogen donor are delivered into a second desulfurization reactor from the bottom of the second desulfurization reactorIn a reactor, the weight hourly space velocity of the oil gas raw material is 0.1 to 100 h at the temperature of 300 to 550 ℃, preferably 350 to 500 ℃, and the absolute pressure is 0.5 to 5MPa, preferably 1.0 to 3.5 MPa ^-1 Preferably 1 to 20 hours ^-1 And (3) carrying out adsorption desulfurization by bringing the rich gas into countercurrent contact with a sulfur-loaded adsorbent flowing downward under reaction conditions in which the molar ratio of hydrogen to oil is 0.01 to 500, preferably 0.05 to 300.

The mixture of the rich gas and/or the hydrogen donor is uniformly distributed in the second desulfurization reactor through the feeding distribution disc and is in good contact with the desulfurization adsorbent in the second desulfurization reactor.

And the sulfur-loaded desulfurization adsorbent in the second desulfurization reactor returns to the first desulfurization reactor from the bottom. After the sulfur-loaded desulfurization adsorbent at the upper part of the first desulfurization reactor is separated from the reaction oil gas, the hydrocarbon adsorbed by the spent adsorbent is removed by steam stripping, and then the spent adsorbent is lifted and conveyed to an adsorbent regenerator. Under the reaction conditions that the regeneration temperature is 300-800 ℃, preferably 350-600 ℃, and the regeneration pressure is 0.1-3.0 MPa, preferably 0.1-1.0 MPa, the regeneration gas is contacted with the regeneration gas input from the lower end of the regenerator to realize regeneration. The regeneration gas comprises oxygen, which may be air or a mixture of air or oxygen and an inert gas, such as nitrogen.

The regenerated desulfurizing adsorbent drawn from the regenerator is stripped to remove its adsorbed impurities (such as adsorbed oxygen), and then lifted and transferred to the adsorbent reducer.

The regenerated desulfurization adsorbent conveyed to the adsorbent reducer is contacted with a reducing gas, and the reduction is carried out under the reducing conditions that the reducing temperature is 250 to 550 ℃, preferably 300 to 450 ℃, and the reducing pressure is 0.2 to 5.0 MPa, preferably 0.5 to 3.5 MPa, wherein the reducing gas is hydrogen or a gas rich in hydrogen.

The reduced desulfurization adsorbent is conveyed into the first desulfurization reactor from the bottom for recycling, so that continuous cycle of adsorption desulfurization reaction, adsorbent regeneration, adsorbent reduction and adsorption desulfurization reaction is realized.

The reaction oil gas obtained from the top of the first desulfurization reactor is a mixture of desulfurized crude gasoline and hydrogen, and the desulfurized rich gas is obtained from the top of the second desulfurization reactor. And the desulfurized rich gas enters the absorption tower from the bottom, and the crude gasoline or the crude gasoline and the stable gasoline are introduced into the absorption tower from the top and are in contact with the rich gas for absorption, so that the desulfurized rich gas with the components of more than 2C and the desulfurized crude gasoline with the components of 2C and less C are obtained.

The operating pressure of the absorption tower is 0.2 to 3.0MPa, preferably 0.5 to 1.6MPa, and the operating temperature is 20 to 100 ℃, preferably 30 to 70 ℃.

The stable gasoline is preferably desulfurized stable gasoline produced by the device.

And (3) delivering the desulfurized rich gas with the components of more than 2C as the gas product at the top of the absorption tower into a reabsorber to contact with the light diesel oil fraction from the catalytic cracking fractionating tower, and obtaining the desulfurized dry gas with the components of more than 2C at the top of the reabsorber. And returning the diesel fraction which absorbs the components with the components more than C2 and is obtained at the bottom of the reabsorption tower to a fractionating tower of the catalytic cracking unit.

The operating pressure of the reabsorption tower is 0.1 to 3.0MPa, preferably 0.5 to 2.5MPa, and the operating temperature is 20 to 100 ℃, preferably 30 to 70 ℃.

The diesel oil fraction from the catalytic cracking fractionating tower is preferably light diesel oil.

And feeding the desulfurized crude gasoline with the reduced components of C2 and below to a desorption tower, obtaining the desulfurized crude gasoline with the further reduced components of C2 and below at the bottom of the desorption tower, mixing the gas product at the top of the desorption tower with the desulfurized rich gas, and returning the gas product to the absorption tower.

The operating pressure of the desorption tower is 0.1 to 3.0MPa, preferably 0.5 to 2.5MPa, and the operating temperature is 20 to 250 ℃, preferably 50 to 200 ℃.

And (3) delivering the desulfurized crude gasoline of which the tower bottom product is C2 and the following components are further reduced into a stabilizing tower, and fractionating in the stabilizing tower to obtain desulfurized liquefied gas and catalytic cracking stable gasoline products.

The operating pressure of the stabilizing tower is 0.1 to 3.0MPa, preferably 0.5 to 2.5MPa, and the operating temperature is 20 to 250 ℃, preferably 50 to 200 ℃.

The desulfurization adsorbent comprises one or a mixture of more than two of various supported metal oxide adsorbents, supported metal oxides loaded with metal promoters and various sulfur conversion agents and sulfur adsorbents. Preferably, the desulfurization adsorbent comprises an adsorbent carrier and a metal component loaded on the adsorbent carrier, wherein the content of the desulfurization adsorbent carrier is 70-95 wt% and the content of the metal component is 5-30 wt% based on the total weight of the desulfurization adsorbent. Preferably, the adsorbent carrier is a mixture of zinc oxide, silica and/or alumina, and the metal component is one or more selected from cobalt, nickel, copper, iron, manganese, molybdenum, tungsten, silver, tin and vanadium. The desulfurization adsorbent is preferably microspherical in shape for facilitating fluidization, and the average particle size of the desulfurization adsorbent is 20 to 200 mu m, preferably 40 to 100 mu m.

The method provided by the present invention is further described below with reference to the accompanying drawings, but the present invention is not limited thereby.

FIG. 1 is a schematic flow diagram of an adsorption desulfurization unit. As shown in FIG. 1, the adsorption desulfurization unit comprises: a first desulfurization reactor 2, a reactor receiver 5, a lock hopper 13 for isolating the reaction-regeneration system, a regenerator feed tank 16 and an adsorbent regenerator 19, which are sequentially communicated, wherein the adsorbent regenerator 19 is sequentially communicated with a regenerator receiver 22, the lock hopper 13 is sequentially communicated with an adsorbent reducer 25, and the adsorbent reducer 25 is communicated with the bottom of the first desulfurization reactor 2 to provide a desulfurization adsorbent for the first desulfurization reactor; wherein the upper part of the first desulfurization reactor 2 is communicated with the upper part of the second desulfurization reactor 8, and the bottom of the second desulfurization reactor is communicated with the bottom of the first desulfurization reactor.

The preheated catalytic cracking fractionating tower crude gasoline and hydrogen enter from the bottom of the first desulfurization reactor 2 through a pipeline 1, contact with a desulfurization adsorbent in the first desulfurization reactor 2 to carry out desulfurization reaction, and the adsorbent loaded with partial sulfur moves upwards along with reaction materials. And at the position of the first desulfurization reactor from bottom to top by 50-90%, part of the desulfurization adsorbent enters the second desulfurization reactor from the upper part under the control of a slide valve, and is in countercurrent contact with the rich gas or the mixture of the rich gas and the hydrogen donor which enters from the bottom of the second desulfurization reactor and is preheated to the required temperature, so that the adsorption desulfurization reaction is carried out.

And carrying out oil agent separation on the reacted rich gas and the desulfurization adsorbent in a settling separation section at the top of the second desulfurization reactor, and sending the separated and desulfurized rich gas to a post-absorption stabilizing unit for treatment through a pipeline 9. The separated desulfurization adsorbent flows downwards, enters the lower part of the first desulfurization reactor at the bottom of the second desulfurization reactor 8, is mixed with the desulfurization adsorbent entering the lower part of the first desulfurization reactor from the reducer and the naphtha and hydrogen from the pipeline 1 and then flows upwards. The reaction oil gas and the desulfurization adsorbent at the top of the first desulfurization reactor 2 are subjected to gas-solid separation, and the separated mixture of the desulfurized crude gasoline and the hydrogen is sent to a subsequent product separation and stabilization system through a pipeline 3.

The separated desulfurization adsorbent carrying sulfur is sent to a reactor receiver 5 from the first desulfurization reactor through a reagent transfer horizontal pipe 4, is sent to a lock hopper 13 through a pipeline 12 after being stripped in the reactor receiver 5, is changed into low-pressure inactive atmosphere from a high-pressure hydrogen environment after being replaced by nitrogen, and is sent to a combustion furnace to be burnt through a pipeline 14. The sulfur-laden sorbent is transported via line 15 to regenerator feed tank 16 where it is lifted by lift gas and passed via line 17 to sorbent regenerator 19. Oxygen-containing gas enters the adsorbent regenerator from the bottom through a pipeline 18, the adsorbent to be regenerated is contacted with the oxygen-containing gas in the adsorbent regenerator 19 for sulfur burning and carbon burning to obtain a regenerated adsorbent, the sulfur-containing flue gas is separated from the regenerated adsorbent at the top of the adsorbent regenerator and then is conveyed to a sulfur production system or is subjected to alkali washing to remove SOx through a pipeline 20, the regenerated adsorbent is conveyed from the adsorbent regenerator to a regenerator receiver 22 through a pipeline 21, is lifted by nitrogen and conveyed to a lock hopper 13 through a pipeline 23, is subjected to stripping displacement and pressure boosting by hydrogen in the lock hopper 13 and then is converted into a high-pressure hydrogen environment, is conveyed to an adsorbent reducer 25 through a pipeline 24 for reduction, and the reduced regenerated adsorbent is conveyed to the first desulfurization reactor 2 through a pipeline 26 to realize continuous adsorption desulfurization reaction.

FIG. 2 is a schematic flow diagram of an absorption stabilization unit. As shown in FIG. 2, the desulfurized rich gas from the adsorptive desulfurization unit is introduced into the absorber tower via line 9

At the bottom of 34, the desulfurized raw gasoline and/or a part of the stabilized gasoline from the adsorption desulfurization unit is introduced into the absorption tower 34 from the upper part through the pipeline 3 to obtain the desulfurized rich gas with the components above C2 reduced and the desulfurized raw gasoline with the components above C2 increased, the desulfurized rich gas with the components above C2 reduced enters the reabsorption tower 36 through the pipeline 31 and contacts the light diesel oil produced by the catalytic device introduced through the pipeline 29 to obtain the desulfurized dry gas component with the components above C2 further reduced, the light diesel oil with the components above C2 absorbed is discharged from the reabsorption tower through the pipeline 38, and the light diesel oil with the components above C2 absorbed is returned to the fractionating tower of the catalytic device through the bottom discharge of the reabsorption tower through the pipeline 42. The desulfurized raw gasoline containing the components of C2 and above is fed into a desorption tower 35 through a pipeline 32 to remove the redundant components (containing C2) below C2, and then fed into a stabilization tower 37 through a pipeline 33, and is fractionated in the stabilization tower 37 to obtain desulfurized liquefied gas 40 and desulfurized catalytic cracking stabilized gasoline 41. The stripper overhead gas is led out through line 30 and enters absorption tower 34 together with the desulfurized rich gas.

The following examples further illustrate the invention but are not intended to limit it accordingly. The raw naphtha and rich gas used in the examples were obtained from a catalytic cracking unit of Yanshan division, a company of petrochemical Co., ltd. The desulfurization adsorbent is FCAS, is produced by Nanjing catalyst division of China petrochemical corporation, takes zinc oxide, silica and alumina as carriers, and loads Ni as an accelerant, and the composition and the physical properties of the desulfurization adsorbent are shown in Table 1.

In the examples and comparative examples, the sulfur content in dry gas and liquefied gas was measured by gas chromatography, and analyzed by GC-SCD on Agilent GC-7890A gas chromatography. The sulfur content in gasoline was analyzed by a ZSX 100X-ray fluorescence spectrometer manufactured by Nippon chemical company. The composition of dry gas, liquefied gas and gasoline hydrocarbons is analyzed and determined by gas chromatography.

The method for calculating the ethylene saturation rate, the propylene saturation rate and the olefin saturation rate in the gasoline comprises the following steps: the mass fractions of the ethylene, the propylene in the liquefied gas and the olefin in the gasoline in the dry gas which is not subjected to desulfurization treatment in the comparative example 2 and is subjected to adsorption desulfurization and absorption stabilization separation in the corresponding examples are measured by taking the mass contents of the ethylene, the propylene in the liquefied gas and the olefin in the gasoline in the dry gas which is not subjected to desulfurization treatment in the comparative example 1 as references, and the mass percentage of the difference value between the reference value and the value after desulfurization in the reference value is taken as the olefin saturation ratio of each.

Ethylene saturation = (mass fraction of ethylene-mass fraction of ethylene after desulfurization in comparative example)/mass fraction of ethylene in comparative example) × 100%;

propylene saturation = (mass fraction of propylene in comparative example-mass fraction of propylene after desulfurization)/mass fraction of propylene in comparative example) × 100%;

gasoline olefin saturation = (mass fraction of gasoline olefins-mass fraction of gasoline olefins after desulfurization in comparative example)/mass fraction of gasoline olefins in comparative example) × 100%.

Comparative example 1

Taking a catalytic cracking device of Yanshan division as an example, rich gas and crude gasoline produced by a catalytic cracking fractionating tower respectively enter an absorption stabilizing unit of the catalytic cracking device, the rich gas enters an absorption tower from the bottom and is absorbed by contacting with the crude gasoline introduced from the top of the absorption tower, material flow at the top of the absorption tower enters a reabsorber from the bottom and is absorbed by countercurrent contacting with light diesel oil from the catalytic cracking fractionating tower, dry gas is obtained at the top of the reabsorber, and the rich light diesel oil obtained at the bottom of the reabsorber returns to the catalytic cracking fractionating tower; the bottom product of the absorption tower passes through a desorption tower and is sent to a stabilization tower, the liquefied gas and the stabilized gasoline are obtained by fractionation in the stabilization tower, and the gas at the top of the desorption tower returns to the absorption tower.

The properties of the non-desulfurized dry gas, liquefied gas and stabilized gasoline obtained are shown in Table 2.

Comparative example 2

And (2) taking the stable gasoline obtained in the comparative example 1 as a raw material, putting the stable gasoline into a gasoline adsorption desulfurization reactor to contact with a desulfurization adsorbent to perform adsorption desulfurization reaction, performing gas-solid separation on reaction oil gas and the sulfur-carrying adsorbent at the top of the adsorption desulfurization reactor, and cooling the reaction oil gas obtained by separation to obtain the desulfurized stable gasoline. The separated sulfur-carrying adsorbent enters an adsorbent regenerator to react with oxygen-containing gas under the regeneration condition for coke burning regeneration, and the regenerated desulfurization adsorbent enters an adsorbent reducer under the reduction reaction conditionThen reacting with reducing gas to obtain reduced desulfurization adsorbent, and returning it into adsorption desulfurization reactor for cyclic use. The adopted adsorbent is FCAS, the properties are shown in table 1, the reaction temperature is 400 ℃, the reaction pressure is 2.0MPa, and the weight hourly space velocity is 5 h ^-1 The reaction was carried out under the reaction conditions of a hydrogen-oil volume ratio of 45, and the reaction results are shown in Table 2.

Examples 1 and 2 illustrate the effect of the desulfurization agent separation method for the catalytic cracking light product provided by the present invention.

Example 1

The method comprises the steps of taking rich gas and crude gasoline as raw materials, firstly entering an adsorption desulfurization reaction unit, then entering an absorption stabilization unit for separation, adopting the flow of the adsorption desulfurization unit shown in figure 1, adopting the flow of the absorption stabilization unit shown in figure 2, wherein a first desulfurization reactor is a small-sized fixed fluidized bed reactor, and a second desulfurization reactor is a reverse flow reactor. The adopted desulphurization adsorbent is FCAS, the desulphurization adsorbent from the reducer enters a first desulphurization reactor from the bottom, the naphtha and hydrogen enter the first desulphurization reactor from the bottom to be contacted with the desulphurization adsorbent for adsorption and desulphurization, and after the reaction is finished, the reaction oil gas and the desulphurization adsorbent are separated to obtain a mixture of the desulfurized naphtha and hydrogen; a portion of the desulfurization adsorbent on top of the adsorbent bed enters the reactor receiver and another portion enters the upper portion of the second desulfurization reactor. Wherein, the position from bottom to top of the first desulfurization reactor from 80 percent is communicated with the position from bottom to top of the second desulfurization reactor from 90 percent. And the rich gas enters the second desulfurization reactor from the bottom, is in countercurrent contact with a desulfurization adsorbent to be adsorbed and desulfurized, and is separated at the upper part of the second desulfurization reactor to obtain the desulfurized rich gas. The operating conditions of the first desulfurization reactor were: the reaction temperature is 400 ℃, the reaction pressure is 1.8MPa, and the weight hourly space velocity is 7h ^-1 The volume ratio of hydrogen to oil is 75, the operating conditions of the second desulfurization reactor are that the reaction temperature is 430 ℃, the reaction pressure is 2.0MPa, and the weight hourly space velocity is 10h ^-1 . The desulfurized rich gas enters an absorption tower from the bottom, the pressure of the top of the absorption tower is 1.428MPa, the temperature of the top of the absorption tower is 30.6 ℃, and the temperature of the bottom of the absorption tower is 45.1 ℃; the desulfurized crude gasoline enters an absorption tower from the upper part and is in countercurrent contact with rich gas for absorption, and the material flow at the top of the absorption tower enters a reabsorption tower from the bottom part and is reacted withThe light diesel oil from the catalytic cracking fractionating tower is subjected to countercurrent contact absorption, the pressure at the top of the reabsorber is 1.220MPa, the temperature at the top of the reabsorber is 31.2 ℃, the temperature at the bottom of the reabsorber is 56.3 ℃, desulfurized dry gas is obtained at the top of the reabsorber, and the rich light diesel oil obtained at the bottom of the reabsorber returns to the catalytic cracking fractionating tower; and (3) desorbing the bottom product of the absorption tower by a desorption tower, wherein the top pressure of the desorption tower is 1.621MPa, the temperature of the top of the tower is 85.1 ℃, the temperature of the bottom of the tower is 153.6 ℃, the bottom product of the tower is sent to a stabilization tower, the top pressure of the stabilization tower is 0.901MPa, the temperature of the top of the tower is 62.1 ℃, the temperature of the bottom of the tower is 143.2 ℃, fractionating in the stabilization tower to obtain desulfurized liquefied gas and stabilized gasoline, and returning the top gas of the desorption tower to the absorption tower. The properties of the resulting desulfurized dry gas, liquefied gas and stabilized gasoline are shown in Table 2.

Example 2

The same reaction scheme and desulfurization adsorbent as in example 1 were used using rich gas and naphtha as raw materials using the desulfurization and separation processes shown in the adsorption desulfurization unit and the adsorption stabilization unit shown in FIGS. 1 and 2, except that the first desulfurization reactor was operated at a reaction temperature of 430 deg.C, a reaction pressure of 1.4 MPa, and a weight hourly space velocity of 8h ^-1 And reacting under the reaction condition that the volume ratio of hydrogen to oil is 100. Preheating rich gas to 430 ℃, then feeding the gas into a second desulfurization reactor, and reacting at 445 ℃, under the reaction pressure of 0.5MPa and the weight hourly space velocity of 12 h ^-1 The first desulfurization reactor obtains desulfurized raw gasoline and hydrogen, and the second desulfurization reactor obtains desulfurized rich gas. Wherein, the position from bottom to top of the first desulfurization reactor is communicated with the position from bottom to top of the second desulfurization reactor by 60 percent. Enabling the desulfurized rich gas to enter an absorption tower from the bottom, wherein the pressure at the top of the absorption tower is 1.425MPa, the temperature at the top of the absorption tower is 31.6 ℃, and the temperature at the bottom of the absorption tower is 42.1 ℃; the desulfurized crude gasoline enters an absorption tower from the upper part and is in countercurrent contact absorption with rich gas, the material flow at the top of the absorption tower enters a reabsorption tower from the bottom and is in countercurrent contact absorption with light diesel oil from a catalytic cracking fractionating tower, the pressure at the top of the reabsorption tower is 1.119MPa, the temperature at the top of the tower is 33.6 ℃, the temperature at the bottom of the tower is 46.5 ℃, desulfurized dry gas is obtained at the top of the reabsorption tower, and the rich light diesel oil is obtained at the bottom of the reabsorption towerReturning the oil to the catalytic cracking fractionating tower; and (3) subjecting the bottom product of the absorption tower to desorption treatment by a desorption tower, wherein the top pressure of the desorption tower is 1.521MPa, the temperature at the top of the tower is 71.6 ℃, the temperature at the bottom of the tower is 138.4 ℃, the bottom product of the tower is sent to a stabilizing tower, the top pressure of the stabilizing tower is 0.786MPa, the temperature at the top of the tower is 61.3 ℃, the temperature at the bottom of the tower is 140.6 ℃, fractionating in the stabilizing tower to obtain desulfurized liquefied gas and stabilized gasoline, and returning the top gas of the desorption tower to the absorption tower. The properties of the resulting desulfurized dry gas, liquefied gas and stabilized gasoline are shown in Table 2.

TABLE 1 desulfurization sorbent composition and Properties

TABLE 2

As can be seen from the results in Table 2, the method provided by the invention simultaneously realizes the desulfurization of gasoline, dry gas and liquefied gas, the yield of the liquefied gas is improved by 0.1 percentage point, and the saturation rates of ethylene and propylene are lower. The yield of the stable gasoline is improved by 0.4-0.5 percent, the olefin saturation rate in the gasoline is reduced, and the octane number loss is reduced.

Claims

1. A method for desulfurizing a catalytically cracked light product, comprising:

(3) The desulfurized raw gasoline obtained from the top of the first desulfurization reactor and the desulfurized rich gas obtained from the top of the second desulfurization reactor are respectively sent to an absorption stabilizing unit for further separation to obtain desulfurized dry gas, liquefied gas and stabilized gasoline;

the operating temperature of the first desulfurization reactor is 200-550 ℃, the absolute pressure is 0.5-5 MPa, and the weight hourly space velocity of the oil gas raw material is 0.1-100 h ^-1 The molar ratio of hydrogen to oil is 0.01 to 1000;

the operating temperature of the second desulfurization reactor is 300-550 ℃, the absolute pressure is 0.5-5 MPa, and the weight hourly space velocity of the oil gas raw material is 0.1-100 h ^-1 The molar ratio of hydrogen to oil is 0.01 to 500;

the desulfurization adsorbent comprises a desulfurization adsorbent carrier and a metal component loaded on the adsorbent carrier, wherein the content of the desulfurization adsorbent carrier is 70-95 wt%, and the content of the metal component is 5-30 wt% based on the total weight of the desulfurization adsorbent.

2. The desulfurization method for the catalytic cracking light product according to claim 1, wherein the desulfurized rich gas enters the absorption tower from the bottom and is absorbed by contacting with the desulfurized naphtha introduced from the top of the absorption tower, the overhead stream of the absorption tower enters the reabsorption tower from the bottom and is absorbed by countercurrent contacting with the light diesel oil from the catalytic cracking fractionating tower, the desulfurized dry gas is obtained from the top of the reabsorption tower, and the light diesel oil rich from the bottom of the reabsorption tower returns to the catalytic cracking fractionating tower; the bottom product of the absorption tower passes through a desorption tower and is sent to a stabilization tower, the product is fractionated in the stabilization tower to obtain desulfurized liquefied gas and stabilized gasoline, and the gas at the top of the desorption tower returns to the absorption tower.

3. The method for desulfurizing a catalytically cracked light product according to claim 1 or 2, wherein the feed gas velocity of the first desulfurization reactor is 0.25 to 10m/s, and the feed gas velocity of the second desulfurization reactor is 0.05 to 1.5m/s; the first desulfurization reactor and the second desulfurization reactor are fluidized bed reactors.

4. The desulfurization method for the catalytic cracking light product as claimed in claim 1, wherein the operating temperature of the first desulfurization reactor is 300 to 500 ℃, the absolute pressure is 1.0 to 3.5 MPa, and the weight hourly space velocity of the oil and gas raw material is 1 to 10h ^-1 The molar ratio of hydrogen to oil is 0.05 to 500.

5. The desulfurization method for the catalytic cracking light product as claimed in claim 1, wherein the operating temperature of the second desulfurization reactor is 350 to 500 ℃, the absolute pressure is 1.0 to 3.5 MPa, and the weight hourly space velocity of the oil and gas raw material is 1 to 20 h ^-1 The molar ratio of hydrogen to oil is 0.05 to 300.

6. The process for desulfurizing a catalytically cracked light product as claimed in claim 1 or 2, wherein the adsorbent regenerator is operated under the following conditions: the regeneration temperature is 300-800 ℃, and the regeneration pressure is 0.1-3.0 MPa.

7. The process for desulfurization of catalytically cracked light products according to claim 6, wherein said adsorbent regenerator is operated under the following conditions: the regeneration temperature is 350-600 ℃, and the regeneration pressure is 0.1-1.0 MPa.

8. The process for desulfurizing a catalytically cracked light product according to claim 2, wherein the absorber is operated under the following conditions: the pressure is 0.2 to 3.0MPa, and the temperature is 20 to 100 ℃; the operating conditions of the desorption tower are as follows: the pressure is 0.1 to 3.0MPa, and the temperature is 20 to 250 ℃; the operating conditions of the reabsorption tower are as follows: the pressure is 0.1 to 3.0MPa, and the temperature is 20 to 100 ℃; the operation conditions of the stabilizing tower are as follows: the pressure is 0.1 to 3.0MPa, and the temperature is 20 to 250 ℃.

9. The process for desulfurizing a catalytically cracked light product according to claim 8, wherein the absorber is operated under the following conditions: the pressure is 0.5 to 1.6MPa, and the temperature is 30 to 70 ℃; the operating conditions of the desorption tower are as follows: the pressure is 0.5 to 2.5MPa, and the temperature is 50 to 200 ℃; the operating conditions of the reabsorption tower are as follows: the pressure is 0.5 to 2.5MPa, and the temperature is 30 to 70 ℃; the operation conditions of the stabilizing tower are as follows: the pressure is 0.5 to 2.5MPa, and the temperature is 50 to 200 ℃.

10. A method for producing low-sulfur light oil products by catalytic cracking is characterized in that catalytic cracking raw materials are introduced into a riser reactor, contacted with a catalytic cracking catalyst, reacted under the catalytic cracking reaction condition, gas-solid separation is carried out on the top of the riser reactor, obtained reaction oil gas enters a catalytic cracking fractionating tower, and rich gas, crude gasoline, light diesel oil, diesel oil and oil slurry are obtained by fractionation; the separated catalytic cracking catalyst is regenerated and then returned to the riser reactor for recycling; introducing the crude gasoline and the rich gas into a first desulfurization reactor and a second desulfurization reactor respectively, performing adsorption desulfurization by adopting the catalytic cracking light product desulfurization method of any one of claims 1 to 9, and performing absorption stabilization separation to obtain desulfurized dry gas, desulfurized liquefied gas and stabilized gasoline.

11. A catalytic cracking light product desulfurization device, which is used for the catalytic cracking light product desulfurization method according to any one of claims 1 to 9, and comprises an adsorption desulfurization unit and an absorption stabilization unit which are communicated in sequence; the adsorption desulfurization unit comprises a first desulfurization reactor (2), a reactor receiver (5), a lock hopper (13) for isolating a reaction-regeneration system, a regenerator feed tank (16) and an adsorbent regenerator (19) which are sequentially communicated, wherein the adsorbent regenerator (19) is sequentially communicated with a regenerator receiver (22), the lock hopper (13), an adsorbent reducer (25) and the bottom of the first desulfurization reactor (2); the absorption stabilizing unit consists of an absorption tower, a desorption tower, a reabsorption tower and a stabilizing tower which are sequentially communicated;

raw material inlets of crude gasoline and hydrogen from the catalytic cracking fractionating tower are arranged at the bottom of the first desulfurization reactor (2); a rich gas raw material inlet from the catalytic cracking fractionating tower is arranged at the bottom of the second desulfurization reactor (8); the position from bottom to top of the first desulfurization reactor is communicated with the position from bottom to top of the second desulfurization reactor by 50-90 percent, so that part of the desulfurization adsorbent enters the second desulfurization reactor; the bottom of the second desulfurization reactor (8) is communicated with the lower part of the first desulfurization reactor, so that the desulfurization adsorbent enters the lower part of the first desulfurization reactor from the bottom of the second desulfurization reactor;

an oil gas outlet at the top of the first desulfurization reactor (2) is communicated with the upper part of the absorption tower, and an oil gas outlet at the top of the second desulfurization reactor (8) is communicated with the bottom of the absorption tower.