Separation method and system for liquefied gas hydrogen adsorption desulfurization product

Abstract

The invention relates to a separation method and system for a liquefied gas hydrogen adsorption desulfurization product, and the method comprises the following steps: feeding light hydrocarbon-containing liquefied gas into a liquefied gas coarse separation tank for gas-liquid separation, and separating to obtain coarse separation tank rich gas and coarse separation tank liquefied gas; feeding the crude separation tank rich gas into a condensation oil tank to obtain condensation oil tank rich gas and condensation oil; feeding the condensed oil into a stabilizing tower, and separating to obtain stabilized gasoline and a stabilizing tower top gas phase; feeding the stabilizing tower top gas phase into a stabilizing tower top reflux tank to obtain stabilizing tower top rich gas and a stabilizing tower top liquid phase, and returning one stream of the stabilizing tower top liquid phase into the stabilizing tower as tower top reflux; and mixing the liquefied gas in the coarse separation tank and the other stream in the liquid phase at the top of the stabilizing tower, feeding the mixture into a desorption tower, and desorbing to obtain desorbed gas at the top of the desorption tower and liquefied gas at the bottom of the desorption tower. According to the technical scheme, when a separation sequence of first stabilization and then desorption is adopted, more than 80wt% of liquefied gas passes through a main separation process and directly enters the desorption tower, so that the separation energy consumption of the stabilization tower is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum processing, and in particular to a method and system for separating products of liquefied gas desulfurization by hydrogen adsorption. Background Art

[0002] Adsorption desulfurization is a green and environmentally friendly desulfurization technology that has gradually developed in recent years. It has the characteristics of ultra-deep desulfurization and can reduce the mass fraction of sulfides to below 1ppm. Compared with traditional hydrodesulfurization technology, adsorption desulfurization can protect the olefins in the raw materials from being saturated by hydrogenation, so that the yield of propylene and butene products in the desulfurized liquefied gas can be retained as much as possible, which increases the profit of subsequent processing of liquefied gas, reduces olefin saturation and hydrogen consumption, and reduces investment costs and operating costs. Therefore, adsorption desulfurization of liquefied gas is a technology with great market prospects and is receiving more and more attention.

[0003] The hydrogen adsorption desulfurization process of liquefied gas will cause a certain amount of dry gas components in the liquefied gas at the outlet of the desulfurization reactor. In order to complete the separation between C2 and C3 components, separation processes such as deep cooling or absorption stabilization are usually used. The deep cooling separation process is generally used in single-component separation scenarios with high separation accuracy requirements. In the oil refining process, the absorption stabilization process is generally more suitable for separating dry gas and liquefied gas. In the process of separating liquefied gas and gasoline in the absorption stabilization process stabilization tower, the grade and amount of public works used are very high. For the mixed product containing hydrogen, light hydrocarbons and liquefied gas components after hydrogen adsorption desulfurization, the conventional absorption stabilization process is directly used for separation, which will inevitably lead to artificial backmixing and repeated separation of liquefied gas and gasoline, resulting in energy waste.

[0004] CN112745938A discloses a method for desulfurizing and separating light products of catalytic cracking, which comprises using a fluidized bed hydrogen adsorption process to desulfurize light products of catalytic cracking, and using a conventional absorption stabilization process to separate the products after desulfurization.

[0005] CN114307549A discloses a process for reducing the energy consumption of the absorption and stabilization system in the oil refining process, which includes increasing the pressure of the absorption tower and the reabsorption tower to 1.5-1.9 MPaG, reducing the pressure of the desorption tower to 0.35-0.50 MPaG, and reducing the pressure of the stabilization tower to 0.55-0.65 MPaG.

[0006] US20170321132A1 discloses a combined energy-saving method for catalytic cracking fractionation and absorption stabilization, which includes using the waste heat of the main distillation tower to drive the refrigeration cycle to reduce the absorption temperature of the absorption process to below 40°C, thereby reducing the amount of circulating absorbent used and reducing system energy consumption.

[0007] However, the energy consumption of existing liquefied gas separation and purification systems needs to be further reduced. Summary of the invention

[0008] The object of the present invention is to provide a method and system for separating products of liquefied gas desulfurization by hydrogen adsorption, so as to further reduce the energy consumption of separation and purification of liquefied gas.

[0009] In order to achieve the above object, the first aspect of the present invention provides a method for separating a liquefied gas hydrogen adsorption desulfurization product, the separation method comprising:

[0010] S1. Sending the liquefied gas containing light hydrocarbons into a liquefied gas rough separation tank for gas-liquid separation to obtain rich gas in the rough separation tank and liquefied gas in the rough separation tank; sending the rich gas in the rough separation tank into a condensed oil tank to obtain rich gas in the condensed oil tank and condensed oil;

[0011] S2, sending the condensed oil into a stabilization tower for separation to obtain a stabilized gasoline and a stabilized tower top gas phase; sending the stabilized tower top gas phase into a stabilized tower top reflux tank to obtain a stabilized tower top rich gas and a stabilized tower top liquid phase; sending the condensed oil tank rich gas into the bottom of an absorption tower, countercurrently contacting with the stabilized gasoline and supplementary absorbent, and extracting the absorber top gas and rich absorbent from the absorption tower;

[0012] S3, returning the rich gas from the top of the stabilizing tower to the condensed oil tank; returning the rich absorbent to the condensed oil tank, and contacting and absorbing with the rich gas from the coarse fraction tank; sending the top gas from the absorption tower to the reabsorption tower, and contacting and absorbing with the lean reabsorbent introduced from the top of the reabsorption tower, to obtain rich reabsorbent and hydrogen-rich dry gas;

[0013] S4, returning one stream of the top liquid phase of the stabilization tower to the stabilization tower as top reflux, mixing the liquefied gas from the rough separation tank and another stream of the top liquid phase of the stabilization tower and sending them to the desorption tower for desorption, to obtain desorbed gas from the top of the desorption tower and liquefied gas from the bottom of the desorption tower; returning the desorbed gas from the top of the desorption tower to the liquefied gas rough separation tank.

[0014] Optionally, the pressure of the light hydrocarbon-containing liquefied gas is 1 to 3 MPa, and the total content of hydrogen and nitrogen in the light hydrocarbon-containing liquefied gas is 1 to 9% by volume, the total content of methane and C2 hydrocarbons is 0.01 to 5% by volume, the total content of C3 hydrocarbons and C4 hydrocarbons is 90 to 98% by volume, and the total content of hydrocarbons above C5 is 0.1 to 0.5% by volume.

[0015] Optionally, the operating conditions of the liquefied gas rough separation tank include: an operating temperature of 30-60°C, an absolute pressure of 1.2-1.4 MPa, and a mass flow ratio of the rich gas in the rough separation tank to the liquefied gas in the rough separation tank of 1:(0.3-99).

[0016] Optionally, the liquefied gas coarse separation tank is a gravity separation tank, a centrifugal separation tank, a baffle separation tank or an adsorption separation tank.

[0017] Optionally, the operating conditions of the condensate oil tank include: an operating temperature of 30 to 60° C. and an absolute pressure of 1.15 to 1.35 MPa.

[0018] Optionally, the absorption tower is a packed tower or a plate tower, and the operating conditions of the absorption tower include: an operating temperature of 20 to 80°C, an absolute pressure of 0.60 to 2.00 MPa, preferably 1.10 to 1.30 MPa; and a boiling range of the stable gasoline of 30 to 200°C.

[0019] Optionally, the desorption tower is a packed tower or a plate tower, and the operating conditions of the desorption tower include: an operating temperature of 20 to 80° C., an absolute pressure of 0.60 to 2.00 MPa, preferably 1.25 to 1.45 MPa.

[0020] Optionally, the reabsorption tower is a packed tower or a plate tower, and the operating conditions of the reabsorption tower include: an operating temperature of 20 to 80°C, an absolute pressure of 0.60 to 2.00 MPa, preferably 1.05 to 1.25 MPa; and a boiling range of the lean reabsorbent of 200 to 350°C.

[0021] Optionally, the stabilization tower is a packed tower or a plate tower, and the operating conditions of the stabilization tower include: an operating temperature of 20 to 250° C., an absolute pressure of 0.60 to 2.00 MPa, preferably 1.2 to 1.4 MPa.

[0022] A second aspect of the present invention provides a separation system for liquefied gas hydrogen adsorption desulfurization products, the separation system comprising a liquefied gas coarse separation tank, a condensed oil tank, an absorption tower, a desorption tower, a reabsorption tower, a stabilization tower and a stabilization tower top reflux tank; the coarse separation tank rich gas outlet of the liquefied gas coarse separation tank is connected to the coarse separation tank rich gas inlet of the condensed oil tank, the condensed oil tank rich gas outlet of the condensed oil tank is connected to the condensed oil tank rich gas inlet of the absorption tower, the condensed oil outlet of the condensed oil tank is connected to the condensed oil inlet of the stabilization tower, the absorber tower top gas outlet of the absorption tower is connected to the absorber tower top gas inlet of the reabsorption tower, and the rich absorbent outlet of the absorption tower is connected to the space between the coarse separation tank and the condensed oil tank. On the pipeline, the stabilizing gasoline outlet of the stabilizing tower is connected to the pipeline for supplementing the absorbent, the stabilizing tower top gas phase outlet of the stabilizing tower is connected to the stabilizing tower top gas phase inlet of the stabilizing tower top reflux tank; the stabilizing tower top rich gas outlet of the stabilizing tower top reflux tank is connected to the pipeline between the rough separation tank and the condensed oil tank, the stabilizing tower top liquid phase outlet of the stabilizing tower top reflux tank is respectively connected to the stabilizing tower top liquid phase inlet of the desorption tower and the stabilizing tower top liquid phase inlet of the stabilizing tower, the rough separation tank liquefied gas outlet of the liquefied gas rough separation tank is connected to the pipeline between the desorption tower and the stabilization tower top reflux tank, and the desorbed gas outlet of the desorption tower is connected to the pipeline containing light hydrocarbon liquefied gas.

[0023] Through the above technical scheme, when the separation sequence of stabilization first and then desorption is adopted, the liquefied gas containing light hydrocarbons is condensed to 40°C in the liquefied gas coarse separation tank, so that more than 80% by weight of the liquefied gas can bypass the main separation process and directly enter the desorption tower, greatly reducing the separation energy consumption of the stabilization tower.

[0024] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a structural schematic diagram of an existing oil refining process absorption stabilization system in a comparative example of the present invention;

[0027] Figure 2 It is a schematic structural diagram of an improved absorption stabilization system for the liquefied gas adsorption desulfurization process in an embodiment of the present invention.

[0028] Description of Reference Numerals

[0029] 1- liquefied gas containing light hydrocarbons; 2- rich gas in the crude fraction tank; 3- liquefied gas in the crude fraction tank; 4- rich gas in the condensed oil tank; 5- rich absorbent; 6- condensed oil; 7- gas at the top of the absorber; 8- poor reabsorbent; 9- rich reabsorbent; 10- hydrogen-rich dry gas; 11- liquefied gas; 12- stable gasoline; 13- supplementary absorbent; 14- rich gas at the top of the stabilizing tower; 15- desorbed gas; 17- liquid phase at the top of the stabilizing tower;

[0030] 40-Liquefied gas coarse separation tank; 50-Condensed oil tank; 60-Absorption tower; 70-Desorption tower; 80-Reabsorption tower; 90-Stabilization tower; 100-Stabilization tower top reflux tank. DETAILED DESCRIPTION

[0031] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0032] The first aspect of the present invention provides a method for separating a liquefied gas hydrogen adsorption desulfurization product, the separation method comprising:

[0033] S1, sending the liquefied gas 1 containing light hydrocarbons into the liquefied gas rough separation tank 40 for gas-liquid separation to obtain the rough separation tank rich gas 2 and the rough separation tank liquefied gas 3; sending the rough separation tank rich gas 2 into the condensed oil tank 50 to obtain the condensed oil tank rich gas 4 and condensed oil 6;

[0034] S2, sending the condensed oil 6 into a stabilization tower 90 to separate and obtain a stabilized gasoline 12 and a stabilized tower top gas phase; sending the stabilized tower top gas phase into a stabilized tower top reflux tank 100 to obtain a stabilized tower top rich gas 14 and a stabilized tower top liquid phase 17; sending the condensed oil tank rich gas 4 into the bottom of an absorption tower 60, countercurrently contacting with the stabilized gasoline 12 and a supplementary absorbent 13, and extracting the absorber top gas 7 and the rich absorbent 5 from the absorption tower 60;

[0035] S3, returning the rich gas 14 at the top of the stabilizing tower to the condensed oil tank 50; returning the rich absorbent 5 to the condensed oil tank 50, and contacting and absorbing with the rich gas 2 in the rough fraction tank; sending the top gas 7 of the absorber tower to the reabsorption tower 80, contacting and absorbing with the lean reabsorbent 8 introduced from the top of the reabsorption tower 80, to obtain rich reabsorbent 9 and hydrogen-rich dry gas 10;

[0036] S4. Return one stream of the top liquid phase 17 of the stabilization tower to the stabilization tower 90 as top reflux, and mix the liquefied gas 3 in the rough separation tank and another stream of the top liquid phase 17 of the stabilization tower to the desorption tower 70 for desorption to obtain the desorbed gas 15 at the top of the desorption tower and the liquefied gas 11 at the bottom of the desorption tower; return the desorbed gas 15 at the top of the desorption tower to the liquefied gas rough separation tank 40.

[0037] In the present invention, most of the liquefied gas containing light hydrocarbons is liquefied and separated in the liquefied gas coarse separation tank. When the separated rich gas in the coarse separation tank is sent to the condensed oil tank, the amount of rich gas at the top of the condensed oil tank is significantly reduced, and then the amount of stable gasoline used in the absorption tower is significantly reduced. Furthermore, the main liquefied gas flow stream of the liquefied gas in the coarse separation tank does not enter the absorption tower and the stabilization tower, and the gas-liquid phase load of the two towers is significantly reduced, which greatly reduces the separation energy consumption of the stabilization tower. At the same time, due to the improvement of the separation sequence, the stable gasoline no longer enters the desorption tower, the equipment size of the three towers can be reduced, and the fixed asset investment is reduced. In addition, the concentration of the hydrogen-rich dry gas at the top of the reabsorption tower is 97% by volume, which can be directly used as circulating hydrogen for the hydrogen adsorption desulfurization device.

[0038] According to the present invention, optionally, the desorbed gas at the top of the desorber tower can be optionally returned to the condensed oil tank.

[0039] According to the present invention, optionally, the rich gas at the top of the stabilization tower can be optionally returned to the liquefied gas rough separation tank.

[0040] According to the present invention, optionally, the pressure of the light hydrocarbon-containing liquefied gas is 1 to 3 MPa, and the total content of hydrogen and nitrogen in the light hydrocarbon-containing liquefied gas is 1 to 9% by volume, the total content of methane and C2 hydrocarbons is 0.01 to 5% by volume, the total content of C3 hydrocarbons and C4 hydrocarbons is 90 to 98% by volume, and the total content of hydrocarbons above C5 is 0.1 to 0.5% by volume.

[0041] According to the present invention, optionally, the operating conditions of the liquefied gas rough separation tank include: an operating temperature of 30-60°C, an absolute pressure of 1.2-1.4MPa, and a mass flow ratio of the rich gas in the rough separation tank to the liquefied gas in the rough separation tank of 1:(0.3-99).

[0042] According to the present invention, optionally, the liquefied gas coarse separation tank is a gravity sedimentation separation tank, a centrifugal separation tank, a baffle separation tank or an adsorption separation tank.

[0043] According to the present invention, optionally, the operating conditions of the condensate oil tank include: an operating temperature of 30 to 60° C. and an absolute pressure of 1.15 to 1.35 MPa.

[0044] According to the present invention, optionally, the absorption tower is a packed tower or a plate tower, and the operating conditions of the absorption tower include: an operating temperature of 20 to 80°C, an absolute pressure of 0.60 to 2.00 MPa, preferably 1.10 to 1.30 MPa; the boiling range of the stable gasoline is 30 to 200°C, and the stable gasoline is preferably catalytically stabilized gasoline.

[0045] According to the present invention, optionally, the desorption tower is a packed tower or a plate tower, and the operating conditions of the desorption tower include: an operating temperature of 20 to 80° C., an absolute pressure of 0.60 to 2.00 MPa, preferably 1.25 to 1.45 MPa.

[0046] According to the present invention, optionally, the reabsorption tower is a packed tower or a plate tower, and the operating conditions of the reabsorption tower include: an operating temperature of 20 to 80°C, an absolute pressure of 0.60 to 2.00 MPa, preferably 1.05 to 1.25 MPa; the boiling range of the lean reabsorbent is 200 to 350°C, and the lean reabsorbent is preferably catalytic light cycle oil.

[0047] According to the present invention, optionally, the stabilization tower is a packed tower or a plate tower, and the operating conditions of the stabilization tower include: an operating temperature of 20 to 250° C., an absolute pressure of 0.60 to 2.00 MPa, preferably 1.2 to 1.4 MPa.

[0048] According to the present invention, optionally, the saturated vapor pressure of the liquefied gas 11 product is <900 KPa, and the content of components above C5 is <1% by volume.

[0049] The second aspect of the present invention provides a separation system for liquefied gas hydrogen adsorption desulfurization products, the separation system comprising a liquefied gas rough separation tank 40, a condensed oil tank 50, an absorption tower 60, a desorption tower 70, a reabsorption tower 80, a stabilization tower 90 and a stabilization tower top reflux tank 100; the rough separation tank rich gas 2 outlet of the liquefied gas rough separation tank 40 is connected to the rough separation tank rich gas 2 inlet of the condensed oil tank 50, the condensed oil tank rich gas 4 outlet of the condensed oil tank 50 is connected to the condensed oil tank rich gas 4 inlet of the absorption tower 60, the condensed oil 6 outlet of the condensed oil tank 50 is connected to the condensed oil 6 inlet of the stabilization tower 90, the absorber tower top gas 7 outlet of the absorption tower 60 is connected to the absorber tower top gas 7 inlet of the reabsorption tower 80, and the rich absorbent 5 outlet of the absorption tower 60 is connected to the space between the rough separation tank 40 and the condensed oil tank 50. On the pipeline, the stabilizing gasoline 12 outlet of the stabilizing tower 90 is connected to the pipeline of the supplementary absorbent 13, and the stabilizing tower top gas phase outlet of the stabilizing tower 90 is connected to the stabilizing tower top gas phase inlet of the stabilizing tower top reflux tank 100; the stabilizing tower top rich gas 14 outlet of the stabilizing tower top reflux tank 100 is connected to the pipeline between the rough separation tank 40 and the condensed oil tank 50, and the stabilizing tower top liquid phase 17 outlet of the stabilizing tower top reflux tank 100 is respectively connected to the stabilizing tower top liquid phase 17 inlet of the desorption tower 70 and the stabilizing tower top liquid phase 17 inlet of the stabilizing tower 90, the rough separation tank liquefied gas 3 outlet of the liquefied gas rough separation tank 40 is connected to the pipeline between the desorption tower 70 and the stabilization tower top reflux tank 100, and the desorption gas 15 outlet of the desorption tower 70 is connected to the pipeline containing light hydrocarbon liquefied gas 1.

[0050] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0051] Comparative Example

[0052] See also Figure 1 The absorption stabilization system of the comparative example includes: a condensed oil tank 50, an absorption tower 60, a desorption tower 70, a reabsorption tower 80 and a stabilization tower 90. The discharge port at the top of the condensed oil tank 50 is connected to the feed port at the bottom of the absorption tower 60, the discharge port at the top of the absorption tower 60 is connected to the feed port at the bottom of the reabsorption tower 80, the discharge port at the bottom of the condensed oil tank 50 is connected to the feed port at the top of the desorption tower 70, and the discharge port at the bottom of the desorption tower 70 is connected to the feed port in the middle of the stabilization tower 90.

[0053] The separation process of the comparative absorption stabilization system is as follows:

[0054] After the light hydrocarbon-containing liquefied gas 1 is cooled to 40°C, it contacts the rich absorbent 5 at the bottom of the absorption tower under a pressure of 1.4 MPa in the condensed oil tank 50 and is separated into gas-liquid two phases. The rich gas 4 at the top of the condensed oil tank, which accounts for 11% of the total weight of the raw materials, is discharged from the top of the condensed oil tank 50 and enters the bottom of the absorption tower 60.

[0055] At a top pressure of 1.3 MPa, the absorption tower 60 uses stable gasoline 12 as an absorbent to absorb more than 99.9% by weight of the liquefied gas component in the rich gas 4 at the top of the condensed oil tank, and at the same time controls the gasoline entrainment amount of the absorption tower top gas 7 to be less than 3.5% by volume. The absorption tower top gas 7 entrained with a small amount of gasoline enters the bottom of the reabsorption tower 80. The top pressure of the reabsorption tower 80 is 1.25 MPa, and the lean reabsorbent 8 is used as the reabsorbent. The hydrogen-rich dry gas 10 is produced from the top of the reabsorption tower 80, and the hydrogen purity is 97%.

[0056] The rich absorbent 5 at the bottom of the absorption tower 60 is sent to the condensed oil tank 50, and the condensed oil 6 at the bottom of the condensed oil tank 50 is sent to the top of the desorption tower 70 to desorb all components below C2. The top pressure of the desorption tower 70 is 1.45MPa, and the desorbed gas 15 at the top of the desorption tower is circulated back to the condensed oil tank 50. The liquid phase 16 at the bottom of the desorption tower is sent to the middle of the stabilization tower 90, and the liquefied gas 11 product is derived from the top of the stabilization tower 90. The top pressure of the stabilization tower 90 is 1.1MPa. The stabilized gasoline 12 and the supplementary absorbent 13 at the bottom of the stabilization tower 90 are circulated back to the absorption tower 60 as an absorbent.

[0057] Example

[0058] This embodiment is implemented by Figure 2 The absorption stabilization system shown is used to separate the products of liquefied gas hydrogen adsorption desulfurization.

[0059] See also Figure 2The separation system includes: a liquefied gas rough separation tank 40, a condensed oil tank 50, an absorption tower 60, a desorption tower 70, a reabsorption tower 80, a stabilization tower 90 and a stabilization tower top reflux tank 100. The rough separation tank rich gas 2 outlet of the liquefied gas rough separation tank 40 is communicated with the rough separation tank rich gas 2 inlet of the condensed oil tank 50, the condensed oil tank rich gas 4 outlet of the condensed oil tank 50 is communicated with the condensed oil tank rich gas 4 inlet of the absorption tower 60, the condensed oil 6 outlet of the condensed oil tank 50 is communicated with the condensed oil 6 inlet of the stabilization tower 90, the absorption tower top gas 7 outlet of the absorption tower 60 is communicated with the absorption tower top gas 7 inlet of the reabsorption tower 80, the rich absorbent 5 outlet of the absorption tower 60 is connected to the pipeline between the rough separation tank 40 and the condensed oil tank 50, the stable gasoline 12 outlet of the stabilization tower 90 is connected to the pipeline of the supplementary absorbent 13, and the stabilization gasoline 13 outlet of the stabilization tower 90 is connected to the pipeline of the supplementary absorbent 13. The gas phase outlet at the top of the stabilizing tower is connected to the gas phase inlet at the top of the stabilizing tower of the reflux tank 100; the rich gas 14 outlet at the top of the stabilizing tower of the reflux tank 100 is connected to the pipeline between the rough separation tank 40 and the condensed oil tank 50, the liquid phase 17 outlet at the top of the stabilizing tower of the reflux tank 100 is respectively connected to the liquid phase 17 inlet at the top of the desorption tower 70 and the liquid phase 17 inlet at the top of the stabilizing tower 90, the liquefied gas 3 outlet at the rough separation tank 40 of the liquefied gas is connected to the pipeline between the desorption tower 70 and the reflux tank 100, and the desorption gas 15 outlet of the desorption tower 70 is connected to the pipeline containing light hydrocarbon liquefied gas 1.

[0060] The method for separating the liquefied gas hydrogen adsorption desulfurization product in this embodiment comprises the following steps:

[0061] S1, sending the liquefied gas 1 containing light hydrocarbons into the liquefied gas rough separation tank 40 for gas-liquid separation to obtain the rough separation tank rich gas 2 and the rough separation tank liquefied gas 3; sending the rough separation tank rich gas 2 accounting for 13% of the total weight of the raw materials into the condensed oil tank 50 to obtain the condensed oil tank rich gas 4 and condensed oil 6;

[0062] S2. The condensed oil 6 is sent to the middle of the stabilization tower 90, and the stabilized gasoline 12 and the components below C4 are cut to separate the stabilized gasoline 12 and the gas phase at the top of the stabilization tower; the gas phase at the top of the stabilization tower is sent to the reflux tank 100 at the top of the stabilization tower to obtain the rich gas 14 at the top of the stabilization tower and the liquid phase 17 at the top of the stabilization tower; the total output of the top of the stabilization tower 90 is 13% of that of the comparative example, which greatly reduces the amount of high-grade heat utilities used in the reboiler at the bottom of the stabilization tower 90 and reduces the energy consumption of the stabilization tower. The rich gas 4 of the condensed oil tank, which accounts for 5% of the total weight of the raw materials, is sent to the bottom of the absorption tower 60, and is countercurrently contacted with the absorbent stabilized gasoline 12 and the supplementary absorbent 13, and more than 99.9% by volume of the liquefied gas components in the rich gas 4 of the condensed oil tank are absorbed, and the absorption tower top gas 7 and the rich absorbent 5 are extracted from the absorption tower 60;

[0063] S3, returning the rich gas 14 at the top of the stabilizing tower to the condensed oil tank 50; returning the rich absorbent 5 to the condensed oil tank 50, and contacting and absorbing with the rich gas 2 in the rough fraction tank; sending the top gas 7 of the absorption tower to the bottom of the reabsorption tower 80, contacting and absorbing with the lean reabsorbent 8 introduced from the top of the reabsorption tower 80, absorbing the residual gasoline component in the top gas 7 of the absorption tower, producing hydrogen-rich dry gas 10 at the top of the reabsorption tower 80, and producing rich reabsorbent 9 at the bottom of the reabsorption tower 80;

[0064] S4. Return one stream of the top liquid phase 17 of the stabilization tower to the stabilization tower 90 as top reflux, mix the liquefied gas 3 in the rough separation tank and another stream of the top liquid phase 17 of the stabilization tower and send them to the desorption tower 70 for desorption to obtain the desorbed gas 15 at the top of the desorption tower and the liquefied gas 11 at the bottom of the desorption tower; return the desorbed gas 15 at the top of the desorption tower to the liquefied gas rough separation tank 40.

[0065] The specific parameters and product properties of the comparative examples and embodiments are as follows:

[0066] The main logistics compositions and properties of the embodiments and comparative examples are shown in Table 1.

[0067] The properties of the absorbent-stabilized gasoline and lean reabsorbent of the examples and comparative examples are shown in Table 2.

[0068] The main process parameters of the embodiments and comparative examples are shown in Table 3.

[0069] Table 1 Main logistics composition and properties of comparative examples and embodiments

[0070]

[0071] Table 2 Properties of absorbent stabilized gasoline and lean reabsorbent

[0072]

[0073] Table 3 Main process parameters of comparative examples and embodiments

[0074] project unit Comparative Example Example Liquefied gas rough separation tank temperature ℃ - 40 Liquefied gas crude tank pressure MPa - 1.40 Condensate tank pressure MPa 1.40 1.35 Condensate tank temperature ℃ 40 40 Theoretical plates of absorption tower piece 30 30 Absorption tower top pressure MPa 1.30 1.30 Absorption tower top temperature ℃ 40 40 Absorption tower bottom temperature ℃ 61.6 69.3 Theoretical plates of reabsorption tower piece 20 20 Reabsorption tower top pressure MPa 1.25 1.25 Reabsorption tower top temperature ℃ 42.4 40.7 Reabsorption tower bottom temperature ℃ 53.2 53.6 Theoretical plates of desorption tower piece 20 20 Desorption tower top pressure MPa 1.45 1.45 Desorption tower top temperature ℃ 61 48.3 Desorption tower bottom temperature ℃ 72.6 61.4 Theoretical plates of stable tower piece 35 35 Stabilize the top pressure MPa 1.1 1.4 Stabilize the top temperature ℃ 59.7 57.3 Stabilize the bottom temperature ℃ 193.0 210.3 Absorbent circulation t / h 21.8 15.7 Reabsorbent circulation t / h 2.4 2.2

[0075] As can be seen from Tables 1-3, the separation method and system for liquefied gas hydrogen adsorption desulfurization products provided by the present invention can ensure that the product quality is consistent with the conventional absorption stabilization system. At the same time, in terms of the operating parameters of each device, only the stabilization tower increases the tower pressure, and the other tower input parameters remain consistent to ensure that the energy consumption comparison is on the same basis. Through the comparison of energy consumption data, it can be seen that in the present invention, since most of the liquefied gas bypasses the stabilization tower and directly enters the desorption tower, the processing capacity and processing difficulty of the stabilization tower are reduced, and the energy consumption of the reboiler at the bottom of the stabilization tower is reduced by 82.0%. Due to the improvement of the separation sequence, the stabilized gasoline no longer enters the desorption tower, and the temperature at the bottom of the desorption tower is reduced while the energy consumption is reduced by 62.5%. The total utility usage of the separation system is reduced by 78.49%.

[0076] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0077] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0078] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for separating products of liquefied gas desulfurization by hydrogen adsorption, characterized in that: The separation method comprises: S1. Sending the liquefied gas containing light hydrocarbons into a liquefied gas rough separation tank for gas-liquid separation to obtain rich gas in the rough separation tank and liquefied gas in the rough separation tank; sending the rich gas in the rough separation tank into a condensed oil tank to obtain rich gas in the condensed oil tank and condensed oil; S2, sending the condensed oil into a stabilization tower for separation to obtain a stabilized gasoline and a stabilized tower top gas phase; sending the stabilized tower top gas phase into a stabilized tower top reflux tank to obtain a stabilized tower top rich gas and a stabilized tower top liquid phase; sending the condensed oil tank rich gas into the bottom of an absorption tower, countercurrently contacting with the stabilized gasoline and supplementary absorbent, and extracting the absorber top gas and rich absorbent from the absorption tower; S3, returning the rich gas from the top of the stabilizing tower to the condensed oil tank; returning the rich absorbent to the condensed oil tank, and contacting and absorbing with the rich gas from the coarse fraction tank; sending the top gas from the absorption tower to the reabsorption tower, and contacting and absorbing with the lean reabsorbent introduced from the top of the reabsorption tower, to obtain rich reabsorbent and hydrogen-rich dry gas; S4, returning one stream of the top liquid phase of the stabilization tower to the stabilization tower as top reflux, mixing the liquefied gas from the rough separation tank and another stream of the top liquid phase of the stabilization tower and sending them to the desorption tower for desorption, to obtain desorbed gas from the top of the desorption tower and liquefied gas from the bottom of the desorption tower; returning the desorbed gas from the top of the desorption tower to the liquefied gas rough separation tank.

2. The separation method according to claim 1, wherein The pressure of the light hydrocarbon-containing liquefied gas is 1 to 3 MPa. In the light hydrocarbon-containing liquefied gas, the total content of hydrogen and nitrogen is 1 to 9% by volume, the total content of methane and C2 hydrocarbons is 0.01 to 5% by volume, the total content of C3 hydrocarbons and C4 hydrocarbons is 90 to 98% by volume, and the total content of hydrocarbons above C5 is 0.1 to 0.5% by volume.

3. The separation method according to claim 1, wherein The operating conditions of the liquefied gas rough separation tank include: an operating temperature of 30-60° C., an absolute pressure of 1.2-1.4 MPa, and a mass flow ratio of the rich gas 2 in the rough separation tank to the liquefied gas 3 in the rough separation tank of 1:(0.3-99).

4. The separation method according to claim 1, wherein The liquefied gas rough separation tank is a gravity sedimentation separation tank, a centrifugal separation tank, a baffle separation tank or an adsorption separation tank.

5. The separation method according to claim 1, wherein The operating conditions of the condensate oil tank include: an operating temperature of 30 to 60° C. and an absolute pressure of 1.15 to 1.35 MPa.

6. The separation method according to claim 1, wherein The absorption tower is a packed tower or a plate tower. The operating conditions of the absorption tower include: an operating temperature of 20 to 80°C, an absolute pressure of 0.60 to 2.00 MPa, preferably 1.10 to 1.30 MPa; and a boiling range of the stable gasoline of 30 to 200°C.

7. The separation method according to claim 1, wherein: The desorption tower is a packed tower or a plate tower, and the operating conditions of the desorption tower include: an operating temperature of 20 to 80° C., an absolute pressure of 0.60 to 2.00 MPa, preferably 1.25 to 1.45 MPa.

8. The separation method according to claim 1, wherein The reabsorption tower is a packed tower or a plate tower, and the operating conditions of the reabsorption tower include: an operating temperature of 20-80°C, an absolute pressure of 0.60-2.00 MPa, preferably 1.05-1.25 MPa; and a boiling range of the lean reabsorbent of 200-350°C.

9. The separation method according to claim 1, wherein: The stabilization tower is a packed tower or a plate tower, and the operating conditions of the stabilization tower include: an operating temperature of 20 to 250° C., an absolute pressure of 0.60 to 2.00 MPa, preferably 1.2 to 1.4 MPa.

10. A separation system for liquefied gas hydrogen adsorption desulfurization products, characterized in that: The separation system includes a liquefied gas rough separation tank, a condensed oil tank, an absorption tower, a desorption tower, a reabsorption tower, a stabilization tower and a stabilization tower top reflux tank; The coarse separation tank rich gas outlet of the liquefied gas coarse separation tank is communicated with the coarse separation tank rich gas inlet of the condensed oil tank, the condensed oil tank rich gas outlet of the condensed oil tank is communicated with the condensed oil tank rich gas inlet of the absorption tower, the condensed oil outlet of the condensed oil tank is communicated with the condensed oil inlet of the stabilization tower, the absorber tower top gas outlet of the absorption tower is communicated with the absorber tower top gas inlet of the reabsorption tower, the rich absorbent outlet of the absorption tower is connected to the pipeline between the coarse separation tank and the condensed oil tank, the stabilized gasoline outlet of the stabilization tower is connected to the pipeline for supplementing absorbent, and the stabilization tower top gas phase outlet of the stabilization tower is communicated with the stabilization tower top gas phase inlet of the stabilization tower top reflux tank; The rich gas outlet at the top of the stabilizing tower of the stabilizing tower top reflux tank is connected to the pipeline between the rough separation tank and the condensed oil tank, the liquid phase outlet at the top of the stabilizing tower of the stabilizing tower top reflux tank is respectively connected to the liquid phase inlet at the top of the stabilizing tower of the desorption tower and the liquid phase inlet at the top of the stabilizing tower of the stabilizing tower, the liquefied gas outlet at the rough separation tank of the liquefied gas rough separation tank is connected to the pipeline between the desorption tower and the stabilizing tower top reflux tank, and the desorbed gas outlet of the desorption tower is connected to the pipeline containing light hydrocarbon liquefied gas.

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