阅读说明：本技术 一种液态烃脱硫醇过剩气循环方法及系统 (Liquid hydrocarbon mercaptan removal excess gas circulation method and system ) 是由 张竹梅 李出和 李依洋 于 2020-04-29 设计创作，主要内容包括：本发明属于石油化工企业液态烃脱硫醇技术领域,公开了一种液态烃脱硫醇过剩气循环方法及系统,该循环方法包括：富碱液、氧气由碱液再生塔下部进入碱液再生塔,工作气由碱液再生塔上部进入碱液再生塔；碱液再生塔的液体出料进入碱液沉降罐,碱液沉降罐上部排出二硫化物油,碱液沉降罐底部排出贫碱液；碱液沉降罐的罐顶气和碱液再生塔的塔顶气作为循环气,经在线分析仪检测,压缩机压缩后进入分液罐气液分离；分液罐的罐顶气与富碱液经进料混合器混合后进入碱液再生塔；分液罐中引入补充水,分液罐的罐底液体经循环泵部分引入压缩机作为封液、其余作为含油水送出。本发明方法及系统可实现废气排放为零,燃料气消耗为零,节省费用。(The invention belongs to the technical field of mercaptan removal of liquid hydrocarbons in petrochemical enterprises, and discloses a method and a system for circulating excess gas generated by mercaptan removal of liquid hydrocarbons, wherein the circulating method comprises the following steps: the rich alkali liquor and oxygen enter the alkali liquor regeneration tower from the lower part of the alkali liquor regeneration tower, and the working gas enters the alkali liquor regeneration tower from the upper part of the alkali liquor regeneration tower; discharging liquid of the alkali liquor regeneration tower into an alkali liquor settling tank, discharging disulfide oil from the upper part of the alkali liquor settling tank, and discharging poor alkali liquor from the bottom of the alkali liquor settling tank; the top gas of the alkali liquor settling tank and the top gas of the alkali liquor regeneration tower are used as circulating gases, and are detected by an online analyzer, and the circulating gases are compressed by a compressor and then enter a liquid separation tank for gas-liquid separation; mixing the tank top gas of the liquid separation tank and the alkali-rich liquid by a feed mixer, and then feeding the mixture into an alkali liquor regeneration tower; make-up water is introduced into the liquid separating tank, liquid at the bottom of the liquid separating tank is introduced into the compressor through the circulating pump part to be used as sealing liquid, and the rest is sent out as oil-containing water. The method and the system can realize zero waste gas emission and zero fuel gas consumption, thereby saving the cost.)

1. The liquid hydrocarbon sweetening excess gas circulation method is characterized by comprising the following steps of:

a. the rich alkali liquor and oxygen enter the alkali liquor regeneration tower from the lower part of the alkali liquor regeneration tower, and the working gas enters the alkali liquor regeneration tower from the upper part of the alkali liquor regeneration tower;

b. discharging liquid of the alkali liquor regeneration tower into an alkali liquor settling tank, discharging disulfide oil from the upper part of the alkali liquor settling tank, and discharging poor alkali liquor from the bottom of the alkali liquor settling tank;

c. the top gas of the alkali liquor settling tank and the top gas of the alkali liquor regeneration tower are used as circulating gas, and the circulating gas is compressed by a compressor after being detected by an online analyzer and then enters a liquid separation tank for gas-liquid separation; or the circulating gas is compressed by a compressor and then enters a liquid separation tank for gas-liquid separation, and the tank top gas of the liquid separation tank is detected by an online analyzer;

d. mixing the tank top gas of the liquid separation tank and the alkali-rich liquid by a feed mixer, and then feeding the mixture into an alkali liquor regeneration tower;

e. make-up water is introduced into the liquid separating tank, liquid at the bottom of the liquid separating tank is introduced into the compressor through the circulating pump part to be used as sealing liquid, and the rest is sent out as oil-containing water.

2. The liquid hydrocarbon sweetening excess gas recycling method of claim 1, wherein the working gas is a hydrocarbon gas, and the hydrocarbon gas is propane and/or propylene.

3. The liquid hydrocarbon sweetening excess gas circulation method of claim 1, wherein the lye settling tank is introduced with an extraction oil which enters the lye settling tank together with the liquid discharge of the lye regeneration tower.

4. The method for recycling a liquid hydrocarbon sweetening excess gas as claimed in claim 1, wherein the content of the working gas in the recycle gas is 50-80 vol%.

5. The liquid hydrocarbon sweetening excess gas recycling method of claim 1, wherein the oxygen content of the oxygen gas is more than 60 vol%, and the oxygen gas enters the alkali regeneration tower through the feed mixer.

6. The liquid hydrocarbon sweetening excess gas recycling process of claim 1, wherein the make-up water is desalted water or fresh water.

7. The liquid hydrocarbon sweetening excess gas recycling method of claim 1, wherein the overhead pressure of the lye regeneration tower is 0.2-0.4 MPaG;

the outlet pressure of the compressor is 0.3-0.7 MPaG;

the tank top pressure of the liquid separation tank is 0.3-0.7MPaG, and the tank top temperature is 35-55 ℃.

8. A liquid hydrocarbon sweetening excess gas circulating system is characterized by comprising an alkali liquor regeneration tower, an alkali liquor settling tank, an online analyzer, a compressor, a liquid separation tank, a circulating pump and a feeding mixer;

an alkali-rich liquid feeding pipeline is arranged at the lower part of the alkali liquor regeneration tower, a working gas supplementing air inlet pipeline and a liquid discharging pipeline are arranged at the upper part of the alkali liquor regeneration tower, a feeding mixer is arranged on the alkali-rich liquid feeding pipeline, an oxygen inlet pipeline is arranged at the lower part of the alkali liquor regeneration tower or the feeding mixer, the liquid discharging pipeline is connected with an inlet of an alkali liquor settling tank, an oil outlet at the upper part of the alkali liquor settling tank is connected with a disulfide oil pipeline, and an alkali liquor outlet at the bottom of the alkali liquor settling tank is connected with a poor alkali liquor pipeline;

the gas outlet of alkali lye settling tank and the top gas outlet of alkali lye regeneration tower link to each other with the inlet line of compressor, and the discharge line of compressor links to each other with the material entry of branch fluid reservoir, the gas outlet pipeline of branch fluid reservoir links to each other with the rich alkali liquor pipeline of feed mixer upper reaches, the inlet line of compressor or be equipped with on-line analysis appearance on the gas outlet pipeline of branch fluid reservoir, be equipped with make-up water inlet pipeline on the branch fluid reservoir, the liquid outlet of branch fluid reservoir links to each other with the entry of circulating pump, the exit linkage of circulating pump has first liquid pipeline and second liquid pipeline, first liquid pipeline links to each other with the sealing liquid mouth of compressor, the second liquid pipeline links to each other with oily water pipeline.

9. The liquid hydrocarbon sweetening excess gas circulation system of claim 8, wherein the liquid outlet line is provided with a stripping oil feed line.

10. The liquid hydrocarbon sweetening excess gas recycle system of claim 8, wherein the compressor is a liquid ring compressor, and the outlet of the compressor is not provided with a cooler;

the liquid separating tank and the alkali liquor settling tank adopt vertical tanks or horizontal tanks.

Technical Field

The invention belongs to the technical field of mercaptan removal of liquid hydrocarbons in petrochemical enterprises, and particularly relates to a method and a system for circulating excess gas generated in mercaptan removal of liquid hydrocarbons.

Background

A liquid hydrocarbon sweetening system is a light-end product refining system of petrochemical enterprises and is mainly used for sweetening impurity components such as mercaptan and the like in saturated liquid hydrocarbon or unsaturated liquid hydrocarbon produced by oil processing devices of an oil refinery, and as mercaptan and NaOH can react to generate sodium mercaptan which is dissolved in alkali liquor and can be easily removed from the liquid hydrocarbon, 15-20 mass% of NaOH alkali liquor is usually used as a circulating extraction solution, mercaptan in the liquid hydrocarbon firstly reacts with NaOH to generate sodium mercaptan which enters the alkali liquor, then air is introduced into the alkali liquor, oxygen in the air reacts with the sodium mercaptan to generate disulfide, the disulfide is soluble in oil and insoluble in the alkali liquor, the disulfide can be directly separated from the alkali liquor by settling, or the extracted oil can be used for enhancing the separation of the disulfide from the alkali liquor by settling, so that the sweetening of the liquid hydrocarbon and the recycling of the alkali liquor are realized.

The conventional technology generally uses air to pass through an alkali liquor regeneration tower once, and utilizes the reaction between oxygen in the air and sodium mercaptide in the alkali liquor, because the oxidation reaction of the sodium mercaptide can be completely carried out under the condition of excess oxygen, and the oxygen excess is 1-2 times of the reaction oxygen consumption, the excess gas component of the liquid hydrocarbon sweetening contains unreacted oxygen, nitrogen, hydrocarbon, water, a small amount of disulfide and the like, and the gas is always a problem which is difficult to treat in a refinery. In recent years, refineries add fuel gas to the excess gas in proportion and introduce the fuel gas into an incinerator or a heating furnace for combustion treatment, thereby alleviating the difficulty in treating the excess gas to some extent. In order to ensure the safety of the excess gas transportation process, the prior art uses a stainless steel pipeline to transport the excess gas while injecting a large amount of fuel gas into the excess gas.

Along with the enlargement of oil product processing scale in recent years, the liquid hydrocarbon output of petrochemical enterprises is increased, the processing capacity of a liquid hydrocarbon sweetening system is increased, the amount of used fuel gas of excess residual gas in the sweetening process is increased, the problems of excessive sulfur content of incinerator exhaust gas or furnace tube corrosion of a heating furnace and the like appear in some refineries, the environmental condition and safe operation of the refineries are seriously influenced, and urgent needs to be solved.

Disclosure of Invention

Aiming at the problems of difficult treatment of excess gas in the existing liquid hydrocarbon sweetening system, excessive sulfur in fuel gas consumption and incineration exhaust smoke caused by combustion treatment, corrosion of furnace tubes, high cost of conveying pipelines, potential safety hazards and the like, the invention aims to provide a liquid hydrocarbon sweetening excess gas circulating method and system, which replace air with oxygen, change the once-through type of air into a gas circulating type in which the excess gas and working gas form circulating gas, do not discharge waste gas to the outside, and can solve the problems of difficult treatment of the excess gas in the liquid hydrocarbon sweetening system of a refinery plant and the safety problems caused by the fluctuation of gas composition.

The first aspect of the present invention provides a liquid hydrocarbon sweetening excess gas recycling method, comprising the steps of:

a. the rich alkali liquor and oxygen enter the alkali liquor regeneration tower from the lower part of the alkali liquor regeneration tower, and the working gas enters the alkali liquor regeneration tower from the upper part of the alkali liquor regeneration tower;

b. discharging liquid of the alkali liquor regeneration tower into an alkali liquor settling tank, discharging disulfide oil from the upper part of the alkali liquor settling tank, and discharging poor alkali liquor from the bottom of the alkali liquor settling tank;

c. the top gas of the alkali liquor settling tank and the top gas of the alkali liquor regeneration tower are used as circulating gas, and the circulating gas is compressed by a compressor after being detected by an online analyzer and then enters a liquid separation tank for gas-liquid separation; or the circulating gas is compressed by a compressor and then enters a liquid separation tank for gas-liquid separation, and the tank top gas of the liquid separation tank is detected by an online analyzer;

d. mixing the tank top gas of the liquid separation tank and the alkali-rich liquid by a feed mixer, and then feeding the mixture into an alkali liquor regeneration tower;

e. make-up water is introduced into the liquid separating tank, liquid at the bottom of the liquid separating tank is introduced into the compressor through the circulating pump part to be used as sealing liquid, and the rest is sent out as oil-containing water.

The second aspect of the invention provides a liquid hydrocarbon sweetening excess gas circulation system, which comprises an alkali liquor regeneration tower, an alkali liquor settling tank, an online analyzer, a compressor, a liquid separation tank, a circulating pump and a feed mixer;

an alkali-rich liquid feeding pipeline is arranged at the lower part of the alkali liquor regeneration tower, a working gas supplementing air inlet pipeline and a liquid discharging pipeline are arranged at the upper part of the alkali liquor regeneration tower, a feeding mixer is arranged on the alkali-rich liquid feeding pipeline, an oxygen inlet pipeline is arranged at the lower part of the alkali liquor regeneration tower or the feeding mixer, the liquid discharging pipeline is connected with an inlet of an alkali liquor settling tank, an oil outlet at the upper part of the alkali liquor settling tank is connected with a disulfide oil pipeline, and an alkali liquor outlet at the bottom of the alkali liquor settling tank is connected with a poor alkali liquor pipeline;

the gas outlet of alkali lye settling tank and the top gas outlet of alkali lye regeneration tower link to each other with the inlet line of compressor, and the discharge line of compressor links to each other with the material entry of branch fluid reservoir, the gas outlet pipeline of branch fluid reservoir links to each other with the rich alkali liquor pipeline of feed mixer upper reaches, the inlet line of compressor or be equipped with on-line analysis appearance on the gas outlet pipeline of branch fluid reservoir, be equipped with make-up water inlet pipeline on the branch fluid reservoir, the liquid outlet of branch fluid reservoir links to each other with the entry of circulating pump, the exit linkage of circulating pump has first liquid pipeline and second liquid pipeline, first liquid pipeline links to each other with the sealing liquid mouth of compressor, the second liquid pipeline links to each other with oily water pipeline.

The liquid hydrocarbon sweetening excess gas circulation system and the method change the existing fuel gas filling combustion treatment mode under the condition of less equipment investment, obviously reduce the influence of the liquid hydrocarbon sweetening excess gas treatment on the environment, have no waste gas discharge and fuel gas consumption, save the related cost of a conveying pipeline and realize the safe long-period operation of the liquid hydrocarbon sweetening system.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention.

FIG. 1 is a schematic process flow diagram of a liquid hydrocarbon sweetening excess gas recycle system in accordance with one embodiment of the present invention.

FIG. 2 is a schematic process flow diagram of one pass of excess gas in a conventional liquid hydrocarbon sweetening system.

Description of the reference numerals

Equipment: 1 alkali liquor regeneration tower; 2, an online analyzer; 3, a compressor; 4, separating the liquid into liquid tanks; 5 circulating pump; 6 feeding mixer; 7, an alkali liquor settling tank;

logistics: a rich lye; b, oxygen; c, working gas; d, supplementing water; e, containing oily water; f disulfide oil; g lean lye; h, extracting oil; i, air; j fuel gas; k off-gas.

Detailed Description

In order that the present invention may be more readily understood, the following detailed description of the invention is given with reference to the accompanying drawings and embodiments, which are given by way of illustration only and are not intended to limit the invention.

According to a first aspect of the present invention, there is provided a liquid hydrocarbon sweetening excess gas recycle process comprising the steps of:

a. the rich alkali liquor and oxygen enter the alkali liquor regeneration tower from the lower part of the alkali liquor regeneration tower, and the working gas enters the alkali liquor regeneration tower from the upper part of the alkali liquor regeneration tower;

b. discharging liquid of the alkali liquor regeneration tower into an alkali liquor settling tank, discharging disulfide oil from the upper part of the alkali liquor settling tank, and discharging poor alkali liquor from the bottom of the alkali liquor settling tank;

c. the top gas of the alkali liquor settling tank and the top gas of the alkali liquor regeneration tower are used as circulating gas, and the circulating gas is compressed by a compressor after being detected by an online analyzer and then enters a liquid separation tank for gas-liquid separation; or the circulating gas is compressed by a compressor and then enters a liquid separation tank for gas-liquid separation, and the tank top gas of the liquid separation tank is detected by an online analyzer;

d. mixing the tank top gas of the liquid separation tank and the alkali-rich liquid by a feed mixer, and then feeding the mixture into an alkali liquor regeneration tower;

e. make-up water is introduced into the liquid separating tank, liquid at the bottom of the liquid separating tank is introduced into the compressor through the circulating pump part to be used as sealing liquid, and the rest is sent out as oil-containing water.

In the present invention, the working gas is a hydrocarbon gas, and the hydrocarbon gas may be propane and/or propylene.

Preferably, the lye settling tank is filled with extraction oil, and the extraction oil and the liquid discharge of the lye regeneration tower enter the lye settling tank together. The introduction of the extraction oil can enhance the sedimentation separation of the disulfide and the alkali liquor, and improve the separation efficiency and the separation effect.

According to the invention, the circulating gas consists of excess gas and working gas, preferably the content of working gas in the circulating gas is 50-80% by volume. The oxygen and hydrocarbon contents in the circulating gas are detected by an on-line analyzer, so that the oxygen concentration required by regeneration can be ensured, and the running safety of the system can be ensured. The circulating gas can be detected before compression and gas-liquid separation, and can also be detected after compression and gas-liquid separation.

Preferably, the oxygen content of the oxygen gas is 60 vol% or more. The oxygen can enter the alkali liquor regeneration tower through the feed mixer or directly enter the alkali liquor regeneration tower.

In the present invention, the supplementary water may be demineralized water or fresh water.

According to a preferred embodiment of the invention, the pressure of the top gas of the alkali liquor regeneration tower and the top gas of the alkali liquor settling tank is increased by a compressor and sent into a liquid separation tank, the gas and the liquid in the liquid separation tank are separated, the top gas of the liquid separation tank is sent back to a feed inlet at the lower part of the alkali liquor regeneration tower by a feed mixer, no exhaust gas is discharged from the system, and the liquid part in the liquid separation tank is sent into a liquid sealing inlet of the compressor by a circulating pump, so that the circulation of make-up water is realized.

According to the invention, the top pressure of the lye regeneration tower is between 0.2 and 0.4 MPaG. The outlet pressure of the compressor is 0.3-0.7 MPaG. The tank top pressure of the liquid separation tank is 0.3-0.7MPaG, and the tank top temperature is 35-55 ℃.

The process parameters which are not limited in the invention can be set conventionally according to the prior art.

According to a second aspect of the invention, the invention provides a liquid hydrocarbon sweetening excess gas circulating system, which comprises an alkali liquor regeneration tower, an alkali liquor settling tank, an online analyzer, a compressor, a liquid separation tank, a circulating pump and a feed mixer;

an alkali-rich liquid feeding pipeline is arranged at the lower part of the alkali liquor regeneration tower, a working gas supplementing air inlet pipeline and a liquid discharging pipeline are arranged at the upper part of the alkali liquor regeneration tower, a feeding mixer is arranged on the alkali-rich liquid feeding pipeline, an oxygen inlet pipeline is arranged at the lower part of the alkali liquor regeneration tower or the feeding mixer, the liquid discharging pipeline is connected with an inlet of an alkali liquor settling tank, an oil outlet at the upper part of the alkali liquor settling tank is connected with a disulfide oil pipeline, and an alkali liquor outlet at the bottom of the alkali liquor settling tank is connected with a poor alkali liquor pipeline;

the gas outlet of alkali lye settling tank and the top gas outlet of alkali lye regeneration tower link to each other with the inlet line of compressor, and the discharge line of compressor links to each other with the material entry of branch fluid reservoir, the gas outlet pipeline of branch fluid reservoir links to each other with the rich alkali liquor pipeline of feed mixer upper reaches, the inlet line of compressor or be equipped with on-line analysis appearance on the gas outlet pipeline of branch fluid reservoir, be equipped with make-up water inlet pipeline on the branch fluid reservoir, the liquid outlet of branch fluid reservoir links to each other with the entry of circulating pump, the exit linkage of circulating pump has first liquid pipeline and second liquid pipeline, first liquid pipeline links to each other with the sealing liquid mouth of compressor, the second liquid pipeline links to each other with oily water pipeline.

Preferably, an extraction oil feeding line is arranged on the liquid discharging pipe line.

In the invention, the compressor is a liquid ring compressor, and a cooler is not arranged at the outlet of the compressor.

According to the invention, the liquid separation tank and the alkali liquor settling tank adopt a vertical tank or a horizontal tank. In particular, a horizontal tank with a gas separation column may be employed.

The liquid hydrocarbon sweetening excess gas circulation system can be used for realizing the liquid hydrocarbon sweetening excess gas circulation method.

Components of the system which are not limited in the invention can be selected conventionally according to the prior art, and belong to the conventional technical means.

The present invention will be described in detail by way of examples.

Examples

This example illustrates the liquid hydrocarbon sweetening excess gas recycle process and system of the present invention.

As shown in figure 1, the invention provides a liquid hydrocarbon sweetening excess gas circulating system, which comprises an alkali liquor regeneration tower 1, an alkali liquor settling tank 7, an online analyzer 2, a compressor 3, a liquid separating tank 4, a circulating pump 5 and a feeding mixer 6; the lower part of the alkali liquor regeneration tower 1 is provided with an alkali liquor rich a feeding pipeline and an oxygen b inlet pipeline, the upper part of the alkali liquor regeneration tower 1 is provided with a working gas c supplementing port air inlet pipeline and a liquid discharging pipeline, the alkali liquor rich a feeding pipeline is provided with a feeding mixer 6, the liquid discharging pipeline is connected with an inlet of an alkali liquor settling tank 7, an oil outlet at the upper part of the alkali liquor settling tank 7 is connected with a disulfide oil f pipeline, and an alkali liquor outlet at the bottom of the alkali liquor settling tank 7 is connected with a poor alkali liquor g pipeline;

the gas outlet of the alkali liquor settling tank 7 and the top gas outlet of the alkali liquor regeneration tower 1 are connected with a feeding pipeline of a compressor 3, a discharging pipeline of the compressor 3 is connected with a material inlet of a liquid separating tank 4, a gas outlet pipeline of the liquid separating tank 4 is connected with an alkali-rich liquid a pipeline on the upstream of a feeding mixer 6, an online analyzer 2 is arranged on the feeding pipeline of the compressor 3, a make-up water d inlet pipeline is arranged on the liquid separating tank 4, a liquid outlet of the liquid separating tank 4 is connected with an inlet of a circulating pump 5, an outlet of the circulating pump 5 is connected with a first liquid pipeline and a second liquid pipeline, the first liquid pipeline is connected with a liquid sealing port of the compressor 3, and the second liquid pipeline is connected with an oil-containing water e pipeline.

And a pumping oil h feeding pipeline is arranged on the liquid discharging pipeline.

The compressor 3 is a liquid ring compressor, and a cooler is not arranged at the outlet of the compressor 3.

The liquid separation tank 4 adopts a vertical tank. The alkali liquor settling tank 7 adopts a horizontal tank with a gas separation column.

The liquid hydrocarbon sweetening excess gas circulation method is realized by adopting the system and comprises the following steps:

a. the rich alkali liquor a and the oxygen b enter the alkali liquor regeneration tower 1 from the lower part of the alkali liquor regeneration tower 1, and the working gas c enters the alkali liquor regeneration tower 1 from the upper part of the alkali liquor regeneration tower 1;

b. discharging the liquid of the alkali liquor regeneration tower 1 into an alkali liquor settling tank 7, discharging disulfide oil f from the upper part of the alkali liquor settling tank 7, and discharging poor alkali liquor g from the bottom of the alkali liquor settling tank 7;

c. the top gas of the alkali liquor settling tank 7 and the top gas of the alkali liquor regeneration tower 1 are used as circulating gas, and the circulating gas is compressed by a compressor 3 after being detected by an online analyzer 2 and then enters a liquid separation tank 4 for gas-liquid separation;

d. the tank top gas of the liquid separation tank 4 and the rich alkali solution a are mixed by a feed mixer 6 and then enter an alkali solution regeneration tower 1;

e. make-up water d is introduced into the liquid separation tank 4, part of the liquid at the bottom of the liquid separation tank 4 is introduced into the compressor 3 through the circulating pump 5 to be used as sealing liquid, and the rest is sent out as oil-containing water e.

The working gas c is propylene; and pumping oil h is introduced into the alkali liquor settling tank 7, and the pumping oil h and the liquid discharge at the upper part of the alkali liquor regeneration tower 1 enter the alkali liquor settling tank 7 together.

The circulating gas consists of excess gas and working gas, and the content of the working gas in the circulating gas is 70 volume percent. The oxygen content of the oxygen gas b was 99.5 vol%. The make-up water d is demineralized water.

The pressure at the top of the alkali liquor regeneration tower 1 is 0.3 MPaG. The outlet pressure of the compressor 3 was 0.55 MPaG. The tank top pressure of the liquid separation tank 4 is 0.5MPaG, and the tank top temperature is 40 ℃.

In the embodiment, the flow of the alkali-rich liquid a is 12t/h, the flow of the oxygen b is 6Kg/h, the flow of the make-up water d is 50Kg/h, the flow of the make-up working gas c during normal operation is 0Kg/h, and the system does not discharge waste gas.

Comparative example

As shown in fig. 2, the excess gas one-pass system in the existing liquid hydrocarbon sweetening system comprises an alkali liquor regeneration tower 1, a feed mixer 6 and an alkali liquor settling tank 7; the method comprises the following steps that an alkali-rich liquid a enters a feed inlet of an alkali regeneration tower 1 through a feed mixer 6, an extraction oil h enters an inlet pipeline of the feed mixer 6 and is mixed with the alkali-rich liquid a to enter the tower, air i enters an air i inlet at the lower part of the alkali regeneration tower 1, fuel gas j enters a fuel gas j inlet at the upper part of the alkali regeneration tower 1, a tower top gas outlet of the alkali regeneration tower 1 is connected with a waste gas k pipeline, a liquid discharge port of the alkali regeneration tower 1 is connected with an inlet of an alkali settling tank 7, a gas outlet pipeline of the alkali settling tank 7 is connected with a gas pipeline at the top of the alkali regeneration tower 1, an oil outlet at the upper part of the alkali settling tank 7 is connected with a disulfide oil f pipeline, and an alkali liquor outlet at the bottom of the alkali settling tank 7 is connected with a poor alkali liquor g pipeline.

In the comparative example, the flow rate of the alkali-rich liquid a is 12t/h, the flow rate of the air i is 65Kg/h, the flow rate of the fuel gas j is 16Kg/h, and the flow rate of the discharged waste gas is 100Kg/h in normal operation.

Compared with a comparative example, the liquid hydrocarbon sweetening excess gas circulation system and the method can save the consumption of the fuel gas by 16Kg/h and 134.4t of the fuel gas each year by less equipment investment under the condition of not changing matched facilities such as the alkali liquor regeneration tower 1, the feed mixer 6, the alkali liquor settling tank 7 and the like, and simultaneously, the amount of the discharged waste gas is reduced to zero from 100 Kg/h.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the illustrated embodiments.