A method and system for separating liquefied gas hydrogen adsorption desulfurization products

Abstract

The application relates to a liquefied gas hydrogen adsorption desulfurization product separation method and system, which comprises the following steps: sending light hydrocarbon liquefied gas into a liquefied gas rough separation tank for gas-liquid separation, and obtaining rough separation tank rich gas and rough separation tank liquefied gas; sending the rough separation tank rich gas into a condensed oil tank to obtain condensed oil tank rich gas and condensed oil; sending the condensed oil into a stabilizer column for separation to obtain stabilized gasoline and stabilizer column overhead gas phase; sending the stabilizer column overhead gas phase into a stabilizer column overhead reflux tank to obtain stabilizer column overhead rich gas and stabilizer column overhead liquid phase, and sending a part of the stabilizer column overhead liquid phase back into the stabilizer column as column overhead reflux; and mixing the rough separation tank liquefied gas and another part of the stabilizer column overhead liquid phase, and sending the mixture into a desorption tower for desorption to obtain desorption tower overhead desorption gas and desorption tower bottom liquefied gas. Through the technical scheme, when a stable and then desorption separation sequence is adopted, more than 80% of liquefied gas by weight crosses the main separation process and directly enters the desorption tower, and the separation energy consumption of the stabilizer column is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum processing, in particular to a separation method and system for liquefied gas hydrogenation adsorption desulfurization products. BACKGROUND

[0002] Adsorption desulfurization method is a green and environmentally friendly desulfurization technology that has been gradually developed in recent years, and has the characteristics of ultra-deep desulfurization, which can reduce the mass fraction of sulfides to below 1ppm. Compared with traditional hydrogenation desulfurization technology, adsorption desulfurization can protect the olefins in the raw material from being hydrogenated to saturation, so that the propylene and butene product yield in the liquefied gas after desulfurization can be retained as much as possible, thereby improving the profit of subsequent liquefied gas processing, reducing hydrogen consumption while reducing olefin saturation, and reducing 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 from people.

[0003] The liquefied gas hydrogenation adsorption desulfurization process will cause the liquefied gas at the outlet of the desulfurization reactor to contain a certain amount of dry gas components. In order to complete the separation between C2 and C3 components, deep cooling or absorption stabilization separation processes are usually used. Deep cooling separation process is generally used in single-component separation scenarios with high separation precision requirements. For the separation of dry gas and liquefied gas in the refining process, it is more appropriate to use the absorption stabilization process. In the process of cutting the liquefied gas and gasoline in the absorption stabilization tower, the grade and amount of utilities used are very high. If the mixed product containing hydrogen, light hydrocarbons and liquefied gas and other components after hydrogenation adsorption desulfurization is directly separated by using the conventional absorption stabilization process, it will inevitably cause artificial backmixing and repeated separation of liquefied gas and gasoline, resulting in energy waste.

[0004] CN112745938A discloses a catalytic cracking light product desulfurization and separation method, which includes using a fluidized bed hydrogenation adsorption process to desulfurize the catalytic cracking light product, and using a conventional absorption stabilization process to separate the desulfurized product.

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

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

[0007] However, the energy consumption of the existing liquefied gas separation and purification system still needs to be further reduced. SUMMARY

[0008] The purpose of the present application is to provide a liquefied gas hydrogen adsorption desulfurization product separation method and system to further reduce the energy consumption of liquefied gas separation and purification.

[0009] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a liquefied gas hydrogen adsorption desulfurization product separation method, which comprises:

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

[0011] S2, separating the condensed oil in a stabilizing tower to obtain a stabilized gasoline and a stabilizing tower overhead gas phase; sending the stabilizing tower overhead gas phase into a stabilizing tower overhead reflux tank to obtain a stabilizing tower overhead rich gas and a stabilizing tower overhead liquid phase; and sending the condensed oil tank rich gas into the bottom of an absorption tower to contact with the stabilized gasoline and a supplementary absorbent in countercurrent, and leading out an absorption tower overhead gas and a rich absorbent from the absorption tower;

[0012] S3, returning and sending the stabilizing tower overhead rich gas into the condensed oil tank; returning and sending the rich absorbent into the condensed oil tank to contact and absorb the rough separation tank rich gas; and sending the absorption tower overhead gas into a reabsorption tower to contact and absorb the lean reabsorption agent introduced into the reabsorption tower overhead to obtain a rich reabsorption agent and a rich hydrogen dry gas;

[0013] S4, returning and sending a part of the stabilizing tower overhead liquid phase into the stabilizing tower as a tower overhead reflux, mixing and sending the rough separation tank liquefied gas and another part of the stabilizing tower overhead liquid phase into a desorption tower for desorption to obtain a desorption tower overhead desorption gas and a desorption tower bottom liquefied gas; and returning and sending the desorption tower overhead desorption gas into the liquefied gas rough separation tank.

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

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

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

[0017] Optionally, the operating conditions of the condensed oil tank include that the operating temperature is 30-60℃, and the absolute pressure is 1.15-1.35MPa.

[0018] Optionally, the operating conditions of the absorption tower include that the operating temperature is 20-80℃, the absolute pressure is 0.60-2.00MPa, preferably 1.10-1.30MPa, and the boiling range of the stable gasoline is 30-200℃.

[0019] Optionally, the operating conditions of the desorption tower include that the operating temperature is 20-80℃, the absolute pressure is 0.60-2.00MPa, preferably 1.25-1.45MPa.

[0020] Optionally, the operating conditions of the reabsorption tower include that the operating temperature is 20-80℃, the absolute pressure is 0.60-2.00MPa, preferably 1.05-1.25MPa, and the boiling range of the lean reabsorber is 200-350℃.

[0021] Optionally, the operating conditions of the stable tower include that the operating temperature is 20-250℃, the absolute pressure is 0.60-2.00MPa, preferably 1.2-1.4MPa.

[0022] The second aspect of the present application provides a separation system for liquefied gas hydrogen adsorption desulfurization products, which comprises a liquefied gas rough separation tank, a condensed oil tank, an absorption tower, a desorption tower, a reabsorption tower, a stabilizing tower and a stabilizing tower top reflux tank; a rough separation tank rich gas outlet of the liquefied gas rough separation tank is communicated with a rough separation tank rich gas inlet of the condensed oil tank, a condensed oil tank rich gas outlet of the condensed oil tank is communicated with a condensed oil tank rich gas inlet of the absorption tower, a condensed oil outlet of the condensed oil tank is communicated with a condensed oil inlet of the stabilizing tower, an absorption tower top gas outlet of the absorption tower is communicated with an absorption tower top gas inlet of the reabsorption tower, an absorption tower rich absorbent outlet of the absorption tower is connected to a pipeline between the rough separation tank and the condensed oil tank, a stabilizing gasoline outlet of the stabilizing tower is connected to a pipeline of supplementary absorbent, a stabilizing tower top gas phase outlet of the stabilizing tower is communicated with a stabilizing tower top gas phase inlet of the stabilizing tower top reflux tank; a 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, a stabilizing tower top liquid phase outlet of the stabilizing tower top reflux tank is respectively communicated with a stabilizing tower top liquid phase inlet of the desorption tower and a stabilizing tower top liquid phase inlet of the stabilizing tower, a rough separation tank liquefied gas outlet of the liquefied gas rough separation tank is connected to a pipeline between the desorption tower and the stabilizing tower top reflux tank, and a desorption gas outlet of the desorption tower is connected to a pipeline of light hydrocarbon-containing liquefied gas.

[0023] By the above technical solution, when the separation sequence of stabilizing first and then desorbing is adopted, the light hydrocarbon-containing liquefied gas is condensed to 40 DEG C in the liquefied gas rough separation tank, so that more than 80% by weight of the liquefied gas can cross the main separation process and directly enter the desorption tower, thereby greatly reducing the separation energy consumption of the stabilizing tower.

[0024] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

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

[0026] Figure 1 The existing refining process absorption stabilizing system structure schematic diagram in the present application comparative example;

[0027] Figure 2 The absorption stabilizing system structure schematic diagram in the present application embodiment for liquefied gas adsorption desulfurization process improved.

[0028] Explanation of reference signs

[0029] 1 - light hydrocarbon containing liquefied gas; 2 - rough cut drum rich gas; 3 - rough cut drum liquefied gas; 4 - condensed oil drum rich gas; 5 - rich absorbent; 6 - condensed oil; 7 - absorber overhead gas; 8 - lean reabsorbent; 9 - rich reabsorbent; 10 - rich hydrogen dry gas; 11 - liquefied gas; 12 - stabilized gasoline; 13 - make-up absorbent; 14 - stabilizer overhead rich gas; 15 - desorbed gas; 17 - stabilizer overhead liquid phase;

[0030] 40 - rough cut liquefied gas drum; 50 - condensed oil drum; 60 - absorber; 70 - desorber; 80 - reabsorber; 90 - stabilizer; 100 - stabilizer overhead reflux drum. DETAILED DESCRIPTION

[0031] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and explanatory and are not intended to limit the present application.

[0032] The first aspect of the present application provides a separation method of liquefied gas hydrogenation adsorption desulfurization product, which comprises:

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

[0034] S2, sending the condensed oil 6 into a stabilizer 90 for separation to obtain stabilized gasoline 12 and stabilizer overhead gas phase; sending the stabilizer overhead gas phase into a stabilizer overhead reflux drum 100 to obtain stabilizer overhead rich gas 14 and stabilizer overhead liquid phase 17; sending the condensed oil drum rich gas 4 into the bottom of an absorber 60 to contact with the stabilized gasoline 12 and make-up absorbent 13 in countercurrent, and leading out absorber overhead gas 7 and rich absorbent 5 from the absorber 60;

[0035] S3, returning and sending the stabilizer overhead rich gas 14 into the condensed oil drum 50; returning and sending the rich absorbent 5 into the condensed oil drum 50 to contact and absorb the rough cut drum rich gas 2; sending the absorber overhead gas 7 into a reabsorber 80 to contact and absorb the lean reabsorbent 8 introduced into the top of the reabsorber 80, to obtain rich reabsorbent 9 and rich hydrogen dry gas 10;

[0036] S4, returning and sending a part of the stabilizer overhead liquid phase 17 into the stabilizer 90 as the overhead reflux, mixing and sending the other part of the stabilizer overhead liquid phase 17 and the rough cut drum liquefied gas 3 into a desorber 70 for desorption to obtain desorber overhead desorbed gas 15 and desorber bottom liquefied gas 11; returning and sending the desorber overhead desorbed gas 15 into the liquefied gas rough cut drum 40.

[0037] In the present application, most of the light hydrocarbon-containing liquefied gas is liquefied and separated in the liquefied gas rough separation tank, and the rich gas separated from the rough separation tank is sent to the condensed oil tank, so that the amount of the rich gas at the top of the condensed oil tank is obviously reduced, and the amount of the stable gasoline used in the absorption tower is obviously reduced. Further, the main liquefied gas stream of the rough separation tank does not enter the absorption tower and the stabilizer tower, so that the gas-liquid phase load of the two towers is significantly reduced, and the energy consumption for separation of the stabilizer tower is greatly reduced. At the same time, due to the improvement of the separation sequence, the stable gasoline no longer enters the desorption tower, and the sizes of the three towers can be reduced, and the fixed asset investment is reduced. In addition, the hydrogen-rich dry gas at the top of the reabsorption tower has a concentration of 97% by volume, and can be directly used as the recycle hydrogen of the hydrogenation adsorption desulfurization device.

[0038] According to the present application, the desorption gas at the top of the desorption tower is optionally returned to the condensed oil tank.

[0039] According to the present application, the rich gas at the top of the stabilizer tower is optionally returned to the liquefied gas rough separation tank.

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

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

[0042] According to the present application, the liquefied gas rough separation tank is a gravity settling type separation tank, a centrifugal type separation tank, a baffle type separation tank or an adsorption type separation tank.

[0043] According to the present application, the operating conditions of the condensed oil tank include an operating temperature of 30-60°C and an absolute pressure of 1.15-1.35 MPa.

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

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

[0046] According to the present application, the resorption tower is a packed tower or a plate tower, and the operating conditions of the resorption tower include: an operating temperature of 20-80℃, an absolute pressure of 0.60-2.00MPa, and preferably 1.05-1.25MPa; the boiling range of the lean resorption agent is 200-350℃, and the lean resorption agent is preferably catalytic light cycle oil.

[0047] According to the present application, the stabilizing tower is a packed tower or a plate tower, and the operating conditions of the stabilizing tower include: an operating temperature of 20-250℃, an absolute pressure of 0.60-2.00MPa, and preferably 1.2-1.4MPa.

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

[0049] The second aspect of the present application provides a separation system for liquefied gas hydrogenation adsorption desulfurization product, which comprises a liquefied gas rough separation tank 40, a condensed oil tank 50, an absorption tower 60, a desorption tower 70, a resorption tower 80, a stabilizing tower 90, and a stabilizing tower overhead reflux tank 100; the rich gas 2 outlet of the rough separation tank of the liquefied gas rough separation tank 40 is communicated with the 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 stabilizing tower 90, the absorption tower overhead gas 7 outlet of the absorption tower 60 is communicated with the absorption tower overhead gas 7 inlet of the resorption 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 stabilizing gasoline 12 outlet of the stabilizing tower 90 is connected to the pipeline of the supplemental absorbent 13, the stabilizing tower overhead gas phase outlet of the stabilizing tower 90 is communicated with the stabilizing tower overhead gas phase inlet of the stabilizing tower overhead reflux tank 100; the stabilizing tower overhead rich gas 14 outlet of the stabilizing tower overhead reflux tank 100 is connected to the pipeline between the rough separation tank 40 and the condensed oil tank 50, the stabilizing tower overhead liquid phase 17 outlet of the stabilizing tower overhead reflux tank 100 is respectively communicated with the stabilizing tower overhead liquid phase 17 inlet of the desorption tower 70 and the stabilizing tower overhead 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 stabilizing tower overhead 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 application will be further illustrated by the following examples, but the present application is not limited by any of them.

[0051] Comparative Example

[0052] Referring to Figure 1 The absorption-stabilization system of the comparative example comprises a condensed oil tank 50, an absorption tower 60, a desorption tower 70, a re-absorption tower 80 and a stabilization tower 90. The outlet of the top of the condensed oil tank 50 is in communication with the inlet of the bottom of the absorption tower 60, the outlet of the top of the absorption tower 60 is in communication with the inlet of the bottom of the re-absorption tower 80, the outlet of the bottom of the condensed oil tank 50 is in communication with the inlet of the top of the desorption tower 70, and the outlet of the bottom of the desorption tower 70 is in communication with the inlet of the middle of the stabilization tower 90.

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

[0054] After the light hydrocarbon-containing liquefied gas 1 is cooled to 40°C, it is contacted with the absorption agent-rich bottom 5 of the absorption tower 60 under the pressure of 1.4 MPa of the condensed oil tank 50 and is separated into gas and liquid phases, and 11% of the total weight of the raw material, the condensed oil-rich gas 4 from the top of the condensed oil tank 50, is discharged and enters the bottom of the absorption tower 60.

[0055] The absorption tower 60 uses the stabilized gasoline 12 as the absorption agent to absorb more than 99.9% of the liquefied gas components in the condensed oil-rich gas 4 from the top of the absorption tower 60 under the top pressure of 1.3 MPa, while controlling the gasoline entrainment of the absorption tower top gas 7 to be less than 3.5% by volume, and the absorption tower top gas 7 with a small amount of gasoline entrainment enters the bottom of the re-absorption tower 80, the top pressure of the re-absorption tower 80 is 1.25 MPa, and the lean re-absorption agent 8 is used as the re-absorption agent, and the hydrogen-rich dry gas 10 is taken out from the top of the re-absorption tower 80, and the hydrogen purity is 97%.

[0056] The absorption agent-rich bottom 5 of the absorption tower 60 is sent to the condensed oil tank 50, 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 the components below C2. The top pressure of the desorption tower 70 is 1.45 MPa, and the desorption tower top desorption gas 15 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, the liquefied gas 11 product is led out from the top of the stabilization tower 90, the top pressure of the stabilization tower 90 is 1.1 MPa, and the stabilized gasoline 12 at the bottom of the stabilization tower 90 is circulated back to the absorption tower 60 as the absorption agent.

[0057] Example

[0058] This example is carried out by the absorption-stabilization system as shown in Figure 2 to separate the liquefied gas hydrogenation adsorption desulfurization product.

[0059] Referring to Figure 2The separation system comprises a liquefied gas rough separation tank 40, a condensed oil tank 50, an absorption tower 60, a desorption tower 70, a re-absorption tower 80, a stabilizing tower 90 and a stabilizing tower overhead 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 stabilizing tower 90, the absorption tower overhead gas 7 outlet of the absorption tower 60 is communicated with the absorption tower overhead gas 7 inlet of the re-absorption 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 stabilizing gasoline 12 outlet of the stabilizing tower 90 is connected to the pipeline of the supplemental absorbent 13, the stabilizing tower overhead gas phase outlet of the stabilizing tower 90 is communicated with the stabilizing tower overhead gas phase inlet of the stabilizing tower overhead reflux tank 100; the stabilizing tower overhead rich gas 14 outlet of the stabilizing tower overhead reflux tank 100 is connected to the pipeline between the rough separation tank 40 and the condensed oil tank 50, the stabilizing tower overhead liquid phase 17 outlet of the stabilizing tower overhead reflux tank 100 is respectively communicated with the stabilizing tower overhead liquid phase 17 inlet of the desorption tower 70 and the stabilizing tower overhead 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 stabilizing tower overhead reflux tank 100, and the desorption gas 15 outlet of the desorption tower 70 is connected to the pipeline of the light hydrocarbon-containing liquefied gas 1.

[0060] The separation method of the liquefied gas hydrogenation adsorption desulfurization product of the embodiment comprises the following steps:

[0061] S1, the light hydrocarbon-containing liquefied gas 1 is sent into the liquefied gas rough separation tank 40 for gas-liquid separation, and the rough separation tank rich gas 2 and the rough separation tank liquefied gas 3 are obtained; 13% of the total weight of the raw material is sent into the condensed oil tank 50, and the condensed oil tank rich gas 4 and the condensed oil 6 are obtained;

[0062] S2, the condensed oil 6 is sent into the middle part of the stabilizing tower 90, the stabilizing gasoline 12 and the C4 component are cut, the stabilizing gasoline 12 and the stabilizing tower overhead gas phase are separated, the stabilizing tower overhead gas phase is sent into the stabilizing tower overhead reflux tank 100, the stabilizing tower overhead rich gas 14 and the stabilizing tower overhead liquid phase 17 are obtained, the total amount of the stabilizing tower overhead is 13% of the amount of the comparative example, the high-grade heat utility consumption of the stabilizing tower 90 reboiler at the bottom is greatly reduced, and the energy consumption of the stabilizing tower is reduced. 5% of the total weight of the raw material is sent into the bottom of the absorption tower 60, is contacted with the absorbent stabilizing gasoline 12 and the supplemental absorbent 13, absorbs more than 99.9% of the liquefied gas component in the condensed oil tank rich gas 4, and the absorption tower overhead gas 7 and the rich absorbent 5 are led out from the absorption tower 60;

[0063] S3, returning the overhead gas 14 of the stabilizer column to the condensate tank 50; returning the rich absorbent 5 to the condensate tank 50 and contacting with the rough cut tank rich gas 2 for absorption; sending the absorption column overhead gas 7 to the reabsorption column 80 at the bottom, contacting with the lean reabsorbent 8 introduced at the top of the reabsorption column 80 for absorption of the residual gasoline components in the absorption column overhead gas 7, and withdrawing the rich hydrogen dry gas 10 at the top of the reabsorption column 80, and withdrawing the rich reabsorbent 9 at the bottom of the reabsorption column 80;

[0064] S4, returning one of the liquid phases 17 at the top of the stabilizer column to the stabilizer column 90 as reflux, mixing the other of the liquid phases 17 at the top of the stabilizer column with the liquefied gas 3 in the rough cut tank and sending the mixture to the desorption column 70 for desorption, obtaining the desorption column overhead gas 15 and the desorption column bottom liquefied gas 11; and returning the desorption column overhead gas 15 to the liquefied gas rough cut tank 40.

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

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

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

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

[0069] Table 1 Main stream compositions and properties of the comparative examples and the examples

[0070]

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

[0072]

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

[0074] Item Unit Comparative Example Example LPG rough fractionation tank temperature ℃ - 40 LPG rough fractionation tank pressure MPa - 1.40 Condensed oil tank pressure MPa 1.40 1.35 Condensed oil tank temperature ℃ 40 40 Absorption column theoretical tray number Block 30 30 Absorption column top pressure MPa 1.30 1.30 Absorption column top temperature ℃ 40 40 Absorption column bottom temperature ℃ 61.6 69.3 Reabsorption column theoretical tray number Block 20 20 Reabsorption column top pressure MPa 1.25 1.25 Reabsorption column top temperature ℃ 42.4 40.7 Reabsorption column bottom temperature ℃ 53.2 53.6 Desorption column theoretical tray number Block 20 20 Desorption column top pressure MPa 1.45 1.45 Desorption column top temperature ℃ 61 48.3 Desorption column bottom temperature ℃ 72.6 61.4 Stabilization column theoretical tray number Block 35 35 Stabilization column top pressure MPa 1.1 1.4 Stabilization column top temperature ℃ 59.7 57.3 Stabilization column bottom temperature ℃ 193.0 210.3 Absorbent circulation amount t / h 21.8 15.7 Reabsorbent circulation amount t / h 2.4 2.2

[0075] From Tables 1-3, it can be seen that the liquefied gas hydrogen adsorption desulfurization product separation method and system provided by the present application can ensure product quality consistent with conventional absorption stable system. At the same time, only the stable column is increased in column pressure among the operating parameters of each device, and the input parameters of the remaining columns are kept consistent to ensure that the energy consumption comparison is at the same benchmark. Through the comparison of energy consumption data, it can be seen that, in the present application, most of the liquefied gas directly enters the desorption tower across the stable tower, the stable tower processing capacity and processing difficulty are reduced, and the stable tower bottom reboiler energy consumption is reduced by 82.0%. Due to the improvement of the separation sequence, the stable gasoline no longer enters the desorption tower, the desorption tower bottom temperature is reduced, and the energy consumption is reduced by 62.5%. The total utility consumption of the separation system is reduced by 78.49%.

[0076] The preferred embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0077] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0078] Furthermore, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the technical concept of the present application, and it should be considered as disclosed content of the present application.

Claims

1. A method for separating liquefied petroleum gas (LPG) products by hydrogen adsorption desulfurization, characterized in that, The separation method includes: S1. The liquefied petroleum gas containing light hydrocarbons is sent into the liquefied petroleum gas coarse separator for gas-liquid separation, and the coarse separator rich gas and coarse separator liquefied petroleum gas are separated; the coarse separator rich gas is sent into the condensate oil tank to obtain condensate oil rich gas and condensate oil. S2. The condensed oil is fed into a stabilizer to separate stabilized gasoline and stabilizer top gas phase; the stabilizer top gas phase is fed into a stabilizer top reflux tank to obtain stabilizer top rich gas and stabilizer top liquid phase; the condensed oil tank rich gas is fed into the bottom of an absorber to contact the stabilized gasoline and supplementary absorbent countercurrently, and the absorber top gas and rich absorbent are discharged from the absorber. S3. The rich gas at the top of the stabilizer tower is returned to the condensate tank; the rich absorbent is returned to the condensate tank and contacted with the rich gas in the coarse separator for absorption; the gas at the top of the absorber tower is sent to the reabsorption tower and contacted with the lean reabsorbent introduced at the top of the reabsorption tower for absorption, to obtain rich reabsorbent and hydrogen-rich dry gas. S4. One stream of the liquid phase at the top of the stabilizer is returned to the stabilizer as top reflux. The liquefied gas from the coarse separator and the other stream of the liquid phase at the top of the stabilizer are mixed and sent to the desorption tower for desorption, resulting in desorbed gas at the top of the desorption tower and liquefied gas at the bottom of the desorption tower. The desorbed gas at the top of the desorption tower is returned to the liquefied gas coarse separator. The operating conditions of the desorption tower include: an operating temperature of 20~80℃ and an absolute pressure of 0.60~2.00MPa; The operating conditions of the stabilizer tower include: an operating temperature of 20~250℃ and an absolute pressure of 0.60~2.00MPa.

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

3. The separation method according to claim 1, wherein, The operating conditions of the liquefied gas coarse separator include: an operating temperature of 30~60℃, an absolute pressure of 1.2~1.4MPa, and a mass flow ratio of rich gas and liquefied gas in the coarse separator to liquefied gas in the coarse separator of 1:(0.3~99).

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

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

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

7. The separation method according to claim 6, wherein, The absolute pressure of the absorption tower is 1.10~1.30MPa.

8. The separation method according to claim 1, wherein, The desorption tower is a packed tower or a plate tower, and the absolute pressure of the desorption tower is 1.25~1.45MPa.

9. 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℃ and an absolute pressure of 0.60~2.00MPa; the boiling range of the lean reabsorbent is 200~350℃.

10. The separation method according to claim 9, wherein, The absolute pressure of the reabsorption tower is 1.05~1.25MPa.

11. The separation method according to claim 1, wherein, The stabilizer is a packed tower or a plate tower, and the absolute pressure of the stabilizer is 1.2~1.4MPa.

12. A separation system for liquefied petroleum gas hydrogen adsorption desulfurization products used in the separation method according to any one of claims 1-11, characterized in that, The separation system includes a liquefied gas coarse separator, a condensate tank, an absorption tower, a desorption tower, a reabsorption tower, a stabilization tower, and a stabilization tower top reflux tank; The rich gas outlet of the liquefied petroleum gas (LPG) coarse separator is connected to the rich gas inlet of the condensate oil tank; the rich gas outlet of the condensate oil tank is connected to the rich gas inlet of the condensate oil tank of the absorber; the condensate oil outlet of the condensate oil tank is connected to the condensate oil inlet of the stabilizer; the absorber top gas outlet of the absorber is connected to the absorber top gas inlet of the reabsorption tower; the rich absorbent outlet of the absorber is connected to the pipeline between the coarse separator and the condensate oil tank; the stabilized gasoline outlet of the stabilizer is connected to the pipeline for replenishing absorbent; and the stabilizer top gas phase outlet of the stabilizer is connected to the stabilizer top gas phase inlet of the stabilizer top reflux tank. The rich gas outlet at the top of the stabilizer tower of the reflux tank is connected to the pipeline between the coarse separator and the condensate tank. The liquid phase outlet at the top of the stabilizer tower of the reflux tank is connected to the liquid phase inlet at the top of the desorption tower and the liquid phase inlet at the top of the stabilizer tower, respectively. The liquefied gas outlet of the coarse separator of the liquefied gas is connected to the pipeline between the desorption tower and the reflux tank at the top of the stabilizer tower. The desorbed gas outlet of the desorption tower is connected to the pipeline containing liquefied gas with light hydrocarbons.

Images