CN112745938B

CN112745938B - Catalytic cracking light product desulfurization and separation method

Info

Publication number: CN112745938B
Application number: CN201911049636.4A
Authority: CN
Inventors: 王文寿; 毛安国; 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: CN112745938A

Abstract

A catalytic cracking light product desulfurization and separation method, introduce rich gas and crude gasoline from catalytic cracker fractionating tower into the fluidized bed desulfurization reactor respectively, contact with desulfurization adsorbent to desulfurize under the hydrogen condition, in the desulfurized reaction oil gas, the rich gas enters the absorption tower from the bottom, contact with desulfurized crude gasoline introduced from the top of the absorption tower to absorb, the material flow of the top of the absorption tower enters the reabsorption tower from the bottom, countercurrent contact with light diesel oil from the catalytic cracking fractionating tower to absorb, the tower top of the reabsorption tower obtains desulfurized dry gas, the rich light diesel oil obtained from the tower 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. The method provided by the invention is suitable for treating rich gas and crude gasoline obtained by a catalytic cracking fractionating tower, the olefin saturation is low, and the obtained refined gasoline has high yield and less octane value loss.

Description

Catalytic cracking light product desulfurization and separation method

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

In the existing catalytic cracking process flow, the reaction product of the catalytic cracking unit is fractionated to obtain components such as rich gas, crude gasoline, light diesel oil, heavy diesel oil, slurry oil and the like. 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 leaves the factory as a product, the liquefied gas can be desulfurized and leaves the 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 desulfurizing method for hydrocarbon oil is a technological process for adsorption desulfurizing light hydrocarbon oil under the condition of hydrogen, and said method has the characteristics of high desulfurizing depth and low hydrogen consumption, and can be used for producing fuel oil whose sulfur content is less than 30 microgram/g. The process for treating catalytic cracking light products, such as catalytic cracking stable gasoline desulfurization, has the problems of low gasoline yield and large gasoline octane number loss of catalytic cracking desulfurization.

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 adsorbing, desulfurizing and separating catalytic cracking light products to obtain desulfurized dry gas, desulfurized liquefied gas and catalytic cracking stable gasoline.

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 fluidized bed desulfurization reactor from the bottom, contacting with a desulfurization adsorbent under a hydrogen condition for desulfurization, and simultaneously flowing upwards, wherein rich gas enters the fluidized bed desulfurization reactor from the position of 30-80% from bottom to top, is mixed with a reactant flow and then is in contact reaction with the desulfurization adsorbent, and reaction oil gas obtained through gas-solid separation enters a gas-liquid separation tank for separation to obtain desulfurized rich gas and crude gasoline; roasting and regenerating the sulfur-carrying desulfurization adsorbent in an adsorbent regenerator, and reducing the regenerated desulfurization adsorbent and returning the reduced desulfurization adsorbent to the fluidized bed desulfurization reactor for recycling;

(2) The desulfurized rich gas enters an absorption tower from the bottom and is absorbed by contacting with desulfurized crude gasoline introduced from the top of the absorption tower, the material flow at the top of the absorption tower enters a reabsorption tower from the bottom and is absorbed by counter-current contact 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.

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 (3) desulfurizing and separating the rich gas and the crude gasoline of the catalytic cracking fractionating tower by adopting the method for desulfurizing and separating the catalytic cracking light product to obtain desulfurized dry gas, desulfurized liquefied gas and desulfurized stable gasoline.

Compared with the prior art, the method for desulfurizing and separating the catalytic cracking light product has the beneficial effects that:

the catalytic cracking rich gas and the crude gasoline are firstly subjected to adsorption desulfurization and then are subjected to absorption stabilization, so that the loss of the gasoline yield caused by the hydro-adsorption desulfurization of the stabilized gasoline in the prior art 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 low-carbon olefin is a target product, and the loss of the low-carbon olefin in the rich gas is less. The method for desulfurizing and separating 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.

Drawings

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

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

Wherein:

2-a fluidized bed desulfurization reactor, 3-a gas-liquid separation tank, 6-an adsorbent receiver, 8-a lock hopper,

11-regenerator feed tank, 14-sorbent regenerator, 17-regenerant receiver, 20-sorbent reducer, 1, 4, 5, 7, 9, 10, 12, 13, 15, 16, 18, 19, 21, 22, 23-pipeline;

24-absorption tower, 25-desorption tower, 26-reabsorption tower, 27-stabilization tower, 38-gas-liquid separation tank, 28, 29, 30, 31, 32, 33, 34, 35, 36 and 37-pipeline.

Detailed Description

The following describes specific embodiments of the present invention in detail. In the specification, reference to the "bottom" of the container means the position from the bottom to 0-10% of the container, and reference to the "top" of the container means the position from the bottom to 90-100% of the container.

(2) The desulfurized rich gas enters an absorption tower from the bottom and is absorbed by contacting with desulfurized crude gasoline introduced from the top of the absorption tower, the material flow at the top of the absorption tower enters a reabsorption tower from the bottom and is absorbed by countercurrent contact 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; and (3) conveying the tower bottom product of the absorption tower to a stabilizing tower after passing through a desorption tower, fractionating in the stabilizing tower to obtain desulfurized liquefied gas and stabilized gasoline, and returning the tower top gas of the desorption tower to the absorption tower.

Specifically, crude gasoline and rich gas are obtained after the oil gas at the top of a fractionating tower of a catalytic cracking unit is subjected to preliminary separation, the rich gas and light gasoline contain C1-C12 hydrocarbon components and possibly other components such as nitrogen, carbon dioxide, hydrogen sulfide and the like, and the sulfur content is 30 to 50000 micrograms/g, preferably more than 50 micrograms/g. After being preheated to the required temperature, the crude gasoline enters the reactor from the bottom of the fluidized bed desulfurization reactor, flows from bottom to top, is contacted with a desulfurization adsorbent in the reactor for desulfurization, the rich gas enters the fluidized bed desulfurization reactor from the middle upper part, is mixed with a reactant flow and is contacted with the desulfurization adsorbent for reaction, and the gas-solid separation is carried out at the top of the fluidized bed desulfurization reactor. The separated to-be-regenerated adsorbent with high sulfur loading enters an adsorbent regenerator to contact with oxygen for regeneration, and the regenerated adsorbent is reduced and then returns to the desulfurization reactor for recycling.

The reaction oil gas obtained by gas-solid separation is passed through a gas-liquid separation device to obtain desulfurized rich gas and crude gasoline, the desulfurized rich gas is fed into an absorption tower from bottom, and is contacted with desulfurized crude gasoline introduced from top of the absorption tower for absorption, the gas product from top of the absorption tower is absorbed and separated with light diesel oil from a catalytic cracking fractionating tower in a reabsorption tower, the desulfurized dry gas is obtained from top of the reabsorption tower, the light diesel oil is obtained from bottom of the reabsorption tower, and the light diesel oil is returned to the catalytic cracking device fractionating tower. The bottom product of the absorption tower passes through a desorption tower and then is sent to a stabilization tower, the product is fractionated in the stabilization tower to obtain desulfurized liquefied gas and catalytically cracked stabilized gasoline, and the top gas of the desorption tower and the desulfurized rich gas are mixed and then enter the absorption tower.

Specifically, the crude gasoline from a catalytic cracking fractionating tower is heated to 100-500 ℃, and enters a fluidized bed adsorption desulfurization reactor together with a hydrogen donor from the bottom. The rich gas is preheated to 150-250 ℃ and enters the fluidized bed desulfurization reactor from the position of 30-80% from bottom to top in the fluidized bed desulfurization reactor.

The fluidized bed desulfurization reactor is preferably a dense-phase bed reactor, and the height of an adsorbent bed layer through which the rich gas passes is controlled to be 10-60% of the total height of the adsorbent bed layer in the fluidized bed desulfurization reactor.

The operating conditions of the fluidized bed desulfurization reactor are as follows: 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 The molar ratio of hydrogen to oil is 0.01 to 5, preferably 0.1 to 1. Under the condition of hydrogen, the reaction oil gas containing crude gasoline and rich gas is contacted with desulfurizing adsorbent to make adsorption desulfurization reaction.

The hydrogen donor may be hydrogen, hydrogen-containing gas, dry gas produced by the apparatus, dry gas produced by the catalytic cracking apparatus, etc., and the hydrogen volume fraction of the hydrogen-containing gas is preferably over 20%.

At the bottom of the fluidized bed adsorption desulfurization reactor, the mixture of the crude gas oil 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.

The desulfurization adsorbent is conveyed into the fluidized bed reactor from the bottom of the fluidized bed reactor.

After the desulfurization adsorbent is separated from the reaction oil gas, the sulfur-loaded to-be-generated adsorbent is stripped to remove the adsorbed hydrocarbons, and then the adsorbent is conveyed to an adsorbent regenerator. The adsorbent regenerator is a fluidized bed reactor, oxygen-containing gas enters the adsorbent regenerator from the bottom, and a spent desulfurization adsorbent is conveyed into the adsorbent regenerator and is contacted with the oxygen-containing gas input from the lower end of the 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, so that the coke is burned and regenerated. The oxygen-containing gas may be air or a mixture of air or oxygen with an inert gas, such as nitrogen.

The regenerated desulfurization adsorbent drawn from the adsorbent regenerator is stripped to remove the impurities (such as adsorbed oxygen) adsorbed by the adsorbent, and then lifted and conveyed to the adsorbent reducer. The regenerated desulfurization adsorbent conveyed into 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 3.5MPa, wherein the reducing gas is hydrogen or a gas rich in hydrogen.

The reduced desulfurization adsorbent is conveyed to the fluidized bed desulfurization reactor from the bottom of the reactor, so that continuous cycle of adsorption desulfurization reaction, adsorbent regeneration, adsorbent reduction and adsorption desulfurization reaction is realized.

And (3) transferring the hydrocarbon oil product after the reaction to a gas-liquid separation tank after heat exchange to obtain the desulfurized rich gas and the crude gasoline. The operating pressure of the gas-liquid separation tank is 0.2 to 4.0MPa, preferably 0.5 to 3.0MPa, the operating temperature is 20 to 300 ℃, and preferably 50 to 200 ℃.

The desulfurized rich gas enters the absorption tower from the bottom after being cooled, and the raw gasoline or the raw gasoline and a part of stable gasoline are introduced from the top of the absorption tower after heat exchange and are in countercurrent contact with the rich gas for absorption to obtain the desulfurized rich gas with components above C2 (without C2) reduced and the desulfurized raw gasoline with components below C2. 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 the desulfurized stable gasoline produced by the device.

And (3) sending the desulfurized rich gas with the components above C2 reduced into a reabsorber to contact with diesel oil fraction from a catalytic cracking fractionating tower to obtain a desulfurized dry gas product with the components above C2 further reduced. The diesel fraction absorbing the components above C2 is returned to the 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 (3) sending the desulfurized crude gasoline with the reduced components of C2 and below to a desorption tower to obtain the desulfurized crude gasoline with the further reduced components of C2 and below, and returning the gas product at the top of the desorption tower and the desulfurized rich gas to the absorption tower after mixing. 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 sending the desulfurized crude gasoline with the further reduced components of C2 and the following components to a stabilizer 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. The preferable desulphurization adsorbent comprises zinc oxide, silica and/or alumina mixture as a carrier, and a reduced metal component is loaded, wherein the metal component is selected from one or more of 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 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 20%, and the hydrogen donor is one or a mixture of more than one selected from tetrahydronaphthalene, decahydronaphthalene and indane.

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 adsorptive desulfurization unit. As shown in fig. 1, the adsorption desulfurization unit comprises a fluidized bed desulfurization reactor 2, a reactor receiver 6, a lock hopper 8 for isolating the reaction-regeneration system, a regenerator feed tank 11, an adsorbent regenerator 14 and a regenerator receiver 17, which are sequentially communicated, wherein the lock hopper is communicated with an adsorbent reducer 20 through a pipeline 19, and the adsorbent reducer 20 is communicated with the bottom of the fluidized bed desulfurization reactor.

The preheated crude gasoline and hydrogen enter from the bottom of the fluidized bed desulfurization reactor 2 through a pipeline 1, contact with a desulfurization adsorbent in the fluidized bed desulfurization reactor 2 to carry out desulfurization reaction, and the adsorbent loaded with partial sulfur moves upwards along with reaction materials. The preheated rich gas enters the fluidized bed desulfurization reactor from the position of 30-80% from bottom to top of the fluidized bed desulfurization reactor 2 through a pipeline 3, is mixed with reaction oil gas and desulfurization adsorbent and then is subjected to desulfurization reaction, the reaction oil gas and adsorbent after the reaction enter a settling separation section at the top of the fluidized bed desulfurization reactor 2 for oil agent separation, and the reaction oil gas after the desulfurization is sent to an absorption stabilizing system through a pipeline 4.

The adsorbent to be generated is sent to a reactor receiver 6 from a horizontal agent transfer pipe 5 at the upper part of a fluidized bed desulfurization reactor 2, is sent to a lock hopper 8 through a pipeline 7 after being stripped in the reactor receiver 6, 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 9. Spent adsorbent is transported via line 10 to regenerator feed tank 11 where it is lifted by lift gas and enters adsorbent regenerator 14 via line 12. The method comprises the steps that oxygen-containing gas enters an adsorbent regenerator from the bottom through a pipeline 13, an adsorbent to be regenerated is contacted with the oxygen-containing gas in an adsorbent regenerator 14 to be subjected to sulfur burning and carbon burning to obtain a regenerated adsorbent, 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 subjected to alkali washing to remove SOx, the regenerated adsorbent is conveyed from the adsorbent regenerator to a regenerator receiver 17 through a pipeline 16, is lifted by nitrogen and conveyed to a lock hopper 8 through a pipeline 18, is subjected to stripping replacement by hydrogen in the lock hopper 8, is boosted and then is converted into a high-pressure hydrogen environment, is conveyed to a reducer 20 through a pipeline 19 to be reduced, and the reduced regenerated adsorbent is conveyed to a fluidized bed desulfurization reactor 2 through a pipeline 21 to realize continuous adsorption desulfurization reaction.

Fig. 2 is a schematic flow diagram of an absorption stabilization system, as shown in fig. 2, desulfurized reaction oil gas obtained by an adsorption desulfurization unit enters a gas-liquid separation tank 38 through a pipeline 4, is subjected to gas-liquid separation by condensation, and the obtained rich gas is discharged through a pipeline 22 and enters an absorption tower 24 from the bottom, the obtained crude gasoline fraction passes through a pipeline 23, or the crude gasoline and a part of the stabilized gasoline enter the absorption tower 24 from the top through a pipeline 23 and are in countercurrent contact absorption with the rich gas, so that desulfurized rich gas with C2 or more components reduced (not containing C2) and desulfurized crude gasoline with C2 or more components increased are obtained, desulfurized rich gas with C2 or more components reduced enters a reabsorber 26 through a pipeline 35 and is in contact with light diesel oil produced by a catalytic device introduced through a pipeline 28, so that desulfurized dry gas components with C2 or more components further reduced are obtained and exit the reabsorber through a pipeline 31, and the light diesel oil with C2 or more components absorbed is returned to the bottom of the catalytic device through a pipeline 29. The desulfurized raw gasoline with the components of more than C2 added enters the desorption tower 25 through a pipeline 36 to remove the redundant components of C2 and the components below, then enters the stabilizing tower 27 through a pipeline 37, and is fractionated in the stabilizing tower 27 to obtain desulfurized liquefied gas 32 and desulfurized catalytic cracking stabilized gasoline 33. The gas at the top of the desorption tower is led out through a pipeline 30 and enters the absorption tower together with the desulfurized rich gas.

The following examples further illustrate the invention but are not intended to limit it accordingly. The raw material used in the examples was a catalytic cracking apparatus of Yanshan division, a company of petrochemical Co., ltd. The desulfurization adsorbent is FCAS, produced by catalyst division of Nanjing, a product of petrochemical Co., ltd, china, and has the properties listed in table 1, wherein zinc oxide, silica and alumina are used as carriers, and Ni is supported as an accelerator.

Analytical methods in examples and comparative examples: the sulfur content in dry gas and liquefied gas is analyzed by a GC-SCD method on an Agilent GC-7890A gas chromatograph, and the sulfur content in gasoline is analyzed by a ZSX 100X-ray fluorescence spectrometer produced by Japan science. 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 in comparative example-mass fraction of gasoline olefins after desulfurization)/mass fraction of gasoline olefins in comparative example) × 100%.

Comparative example 1

Taking a Yanshan catalytic cracking device 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 reabsorption tower 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 reabsorption tower, and the rich light diesel oil obtained at 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 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, feeding 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 separated reaction oil gas to obtain the desulfurized stable gasoline. The separated sulfur-loaded adsorbent enters an adsorbent regeneratorReacting with oxygen-containing gas under the regeneration condition, burning and regenerating, and allowing the regenerated desulfurization adsorbent to enter an adsorbent reducer and react with reducing gas under the reduction reaction condition to obtain reduced desulfurization adsorbent, and returning the reduced desulfurization adsorbent to the adsorption desulfurization reactor for recycling. 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 5h ^-1 The adsorption desulfurization 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. The sulfur content of the stable gasoline is 2.6ppm, the octane number loss is 0.8 unit, and the yield of the refined gasoline is reduced by 0.6 percentage point.

Example 1

Example 1 illustrates the effect of the reaction of simultaneous adsorptive desulfurization of rich gas and naphtha. Taking rich gas and crude gasoline as raw materials, firstly feeding into an adsorption desulfurization reaction unit, feeding into an absorption stabilization unit for separation, feeding the crude gasoline into a fluidized bed desulfurization reactor from the bottom as shown in figure 1, feeding the crude gasoline into the adsorption stabilization unit for separation as shown in figure 2, wherein the adopted desulfurization adsorbent is FCAS, the reaction temperature is 400 ℃, the reaction pressure is 2.0MPa, and the weight hourly space velocity is 5h ^-1 Reacting under the reaction condition of a hydrogen-oil volume ratio of 45, introducing rich gas into a fluidized bed desulfurization reactor from bottom to top 60% of the position of the fluidized bed desulfurization reactor, controlling a desulfurization adsorbent bed layer through which the rich gas passes to be 20% of the total height of an adsorbent bed layer in the reactor, mixing sulfur-containing rich gas with reaction oil gas and a desulfurization adsorbent to perform adsorption desulfurization reaction, introducing the oil gas after the reaction into a gas-liquid separation tank, cooling and separating the oil gas to obtain rich gas and crude gasoline rich gas, and introducing the rich gas and the crude gasoline rich gas into an absorption tower from the bottom, wherein the pressure at the top of the absorption tower is 1.758MPa, the temperature at the top of the absorption tower is 43.6 ℃, and the temperature at the bottom of the absorption tower is 52.7 ℃; crude gasoline separated by the gas-liquid separation tank enters an absorption tower from the upper part and is in countercurrent contact absorption with rich gas, material flow on 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 on the top of the reabsorption tower is 1.632MPa, the temperature on the top of the tower is 42.5 ℃, the temperature on the bottom of the tower is 54.1 ℃, desulfurized dry gas is obtained on the top of the reabsorption tower, and the rich light diesel oil obtained on 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 for desorption treatment, and the tower top pressure of the desorption tower is 1.853MPaThe temperature of the top of the tower is 84.9 ℃, the temperature of the bottom of the tower is 156.8 ℃, the bottom product is sent to a stabilizer, the pressure of the top of the stabilizer is 1.056MPa, the temperature of the top of the tower is 63.8 ℃, the temperature of the bottom of the tower is 174.5 ℃, the product is fractionated in the stabilizer to obtain desulfurized liquefied gas and stabilized gasoline, and the gas at the top of the desorber returns to the absorption tower.

The properties of dry gas, liquefied gas and gasoline are shown in table 2.

Example 2

Example 2 illustrates the effect of the reaction on simultaneous adsorptive desulfurization of rich gas and naphtha. The same reaction procedure as in example 1 was carried out using rich gas and naphtha as raw materials, except that the reaction temperature in the fluidized bed desulfurization reactor was 430 deg.C, the reaction pressure was 1.4 MPa, and the weight hourly space velocity was 8 h ^-1 The method comprises the following steps of reacting under the reaction condition that the volume ratio of hydrogen to oil is 100, preheating rich gas to 430 ℃, then entering the fluidized bed desulfurization reactor from the position of 40% from bottom to top in the fluidized bed desulfurization reactor, controlling the adsorbent bed layer through which the rich gas passes to be 30% of the total height of the adsorbent bed layer in the reactor, and entering oil gas after the reaction into a gas-liquid separation tank to cool and separate the rich gas and the desulfurized crude gasoline. The rich gas enters an absorption tower from the bottom, the pressure at the top of the absorption tower is 1.772MPa, the temperature at the top of the absorption tower is 42.3 ℃, and the temperature at the bottom of the absorption tower is 49.8 ℃; feeding desulfurized crude gasoline into an absorption tower from the upper part, carrying out countercurrent contact absorption with rich gas, feeding the material flow on the top of the absorption tower into a reabsorption tower from the bottom, carrying out countercurrent contact absorption with light diesel oil from a catalytic cracking fractionating tower, wherein the pressure on the top of the reabsorption tower is 1.598MPa, the temperature on the top of the tower is 43.5 ℃, the temperature on the bottom of the tower is 47.6 ℃, obtaining desulfurized dry gas on the top of the reabsorption tower, and returning the rich diesel oil obtained on the bottom of the reabsorption tower 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 1.918MPa, the temperature of the top of the desorption tower is 85.3 ℃, the temperature of the bottom of the desorption tower is 155.2 ℃, the bottom product of the desorption tower is sent to a stabilization tower, the top pressure of the stabilization tower is 0.919MPa, the temperature of the top of the stabilization tower is 59.5 ℃, the temperature of the bottom of the stabilization tower is 169.7 ℃, fractionating in the stabilization tower to obtain desulfurized liquefied gas and stabilized gasoline, and the top gas of the desorption tower returns to the absorption tower.

The properties of the desulfurized dry gas, liquefied gas and stabilized gasoline obtained by the reaction are shown in table 2.

TABLE 1 composition and Properties of desulfurizing adsorbent

TABLE 2

Claims

1. A method for desulfurizing and separating a catalytic cracked light product, comprising:

(1) Introducing crude gasoline from a catalytic cracking fractionating tower into a fluidized bed desulfurization reactor from the bottom, contacting with a desulfurization adsorbent under the hydrogen condition for desulfurization, and simultaneously making the crude gasoline flow upwards, wherein rich gas enters the fluidized bed desulfurization reactor from the position of 30-80% from bottom to top, is mixed with a reactant flow and then contacts and reacts with the desulfurization adsorbent, and reaction oil gas obtained through gas-solid separation enters a gas-liquid separation tank for separation to obtain desulfurized rich gas and crude gasoline; roasting and regenerating the sulfur-carrying desulfurization adsorbent in an adsorbent regenerator, and reducing the regenerated desulfurization adsorbent and returning the reduced desulfurization adsorbent to the fluidized bed desulfurization reactor for recycling;

(2) The desulfurized rich gas enters an absorption tower from the bottom and is absorbed by contacting with desulfurized crude gasoline introduced from the top of the absorption tower, the material flow at the top of the absorption tower enters a reabsorption tower from the bottom and is absorbed by countercurrent contact 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 tower 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 tower top gas of the desorption tower returns to the absorption tower;

wherein the operation temperature of the fluidized bed 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 5;

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 process for desulfurization and separation of a catalytically cracked light product according to claim 1, wherein the rich gas is introduced into the fluidized bed desulfurization reactor at a position ranging from 40% to 70% from the bottom up.

3. The method for desulfurizing and separating a catalytic cracking light product according to claim 1, wherein the operating temperature of the fluidized bed desulfurization reactor is 300 to 500 ℃, the absolute pressure is 1.0 to 3.5MPa, and the weight hourly space velocity of the oil and gas raw material is 1 to 10 h ^-1 The molar ratio of hydrogen to oil is 0.1 to 1.

4. The process for desulfurizing and separating a catalytically cracked light product as set forth in claim 1 or 2, wherein said sulfur-bearing desulfurizing adsorbent is regenerated by reaction with an oxygen-containing gas in an adsorbent regenerator under the operating conditions of: the regeneration temperature is 300-800 ℃, and the regeneration pressure is 0.1-3.0 MPa.

5. The process for desulfurization and separation of catalytically cracked light products of claim 4, 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.

6. The process for desulfurizing and separating a catalytically cracked light product according to claim 1, wherein the knockout drum is operated under the following conditions: the operating pressure is 0.2 to 4.0MPa, and the operating temperature is 20 to 300 ℃; the operating conditions of the absorption tower are as follows: the operating pressure is 0.2 to 3.0MPa, and the operating temperature is 20 to 100 ℃; the operating conditions of the desorption tower are as follows: the operating pressure of the desorption tower is 0.1 to 3.0MPa, and the operating temperature is 20 to 250 ℃; the operating conditions of the reabsorption tower are as follows: the operating pressure of the reabsorption tower is 0.1 to 3.0MPa, and the operating temperature is 20 to 100 ℃; the operation conditions of the stabilizing tower are as follows: the operating pressure of the stabilizing tower is 0.1 to 3.0MPa, and the operating temperature is 20 to 250 ℃.

7. The process for desulfurizing and separating a catalytically cracked light product according to claim 6, wherein the knockout drum is operated under the following conditions: the operating pressure is 0.5 to 3.0MPa, and the operating temperature is 50 to 200 ℃; the operating conditions of the absorption tower are as follows: the operating pressure is 0.5 to 1.6MPa, and the operating temperature is 30 to 70 ℃; the operating conditions of the desorption tower are as follows: the operating pressure of the desorption tower is 0.5 to 2.5MPa, and the operating temperature is 50 to 200 ℃; the operating conditions of the reabsorption tower are as follows: the operating pressure of the reabsorption tower is 0.5 to 2.5MPa, and the operating temperature is 30 to 70 ℃; the operation conditions of the stabilizing tower are as follows: the operating pressure of the stabilizing tower is 0.5 to 2.5MPa, and the operating temperature is 50 to 200 ℃.

8. The process for desulfurizing and separating a light product from catalytic cracking according to claim 1, wherein the sulfur content in the rich gas and naphtha from the catalytic cracking unit is greater than 30 μ g/g.

9. The process for desulfurizing and separating a light product from catalytic cracking of claim 8 wherein the sulfur content of the rich gas and naphtha from the catalytic cracking unit is greater than 50 micrograms/gram.

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, contact with a catalytic cracking catalyst, react under the catalytic cracking reaction condition, carry out gas-solid separation on the top of the riser reactor, enter an obtained reaction oil gas into a catalytic cracking fractionating tower, and obtain rich gas, crude gasoline, light diesel oil, diesel oil and oil slurry by fractionation; the separated catalytic cracking catalyst is regenerated and then returned to the riser reactor for recycling;

the rich gas and the crude gasoline of the catalytic cracking fractionating tower are desulfurized and separated by adopting the method for desulfurizing and separating the catalytic cracking light product as claimed in any one of claims 1 to 9, and the desulfurized dry gas, desulfurized liquefied gas and desulfurized stable gasoline are obtained.