Flare gas recovery method

Abstract

The present invention relates to a flare gas recovery method comprising the steps of: supplying flare gas to a compressor to recover a compressed gaseous fuel; supplying the compressed gaseous fuel to an absorption column to cause a hydrocarbon fuel contained in the gaseous fuel to be absorbed into an absorbent; supplying the absorbent in which the hydrocarbon fuel is absorbed to a stripping column to volatilize and separate the hydrocarbon fuel absorbed in the absorbent; and storing the hydrocarbon fuel separated in the stripping column in a liquid state in a storage tank.

Description

Flare gas recovery method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0005009 filed on January 13, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present application relates to a method for recovering flare gas, and more specifically, to a method for ensuring operational stability of a steam boiler by maintaining a constant fuel supply flow rate in a flare gas recovery system that recovers flare gas and uses it as fuel.

[0005] Flare gas refers to waste gas generated in oil refineries or petrochemical plants, and is a volatile and combustible gas. In particular, the composition of flare gas emitted from petrochemical plants is mainly hydrocarbons with a C8 or lower. Flare systems are operated for the purpose of incinerating waste gas generated from such petrochemical plants and excessive gas resulting from unexpected situations during plant operation.

[0006] The above flare system is composed of a plurality of conduits (pipes) through which flare gas flows to manage, process, and discharge flare gas generated continuously and in large quantities; a flare header that collects discharged gas or liquid; a knockout drum (KO drum) that separates and collects liquid and gas delivered from the flare header; a flare stack configured as an incineration tower, including a pilot burner and an ignition device, to burn and discharge flare gas; and a seal drum to prevent accidents caused by flames flowing back from the flare stack. That is, in a general flare system, flare gas is discharged to the outside through an exhaust and waste gas treatment device called a flare stack. Specifically, flare gas is delivered to the flare stack through pipes, burned in the flare stack, and discharged into the atmosphere.

[0007] However, maintaining flare systems in these general oil refineries or petrochemical plants incurs high costs, and there are significant issues regarding cost losses due to the amount of flare gas released. In addition, when flare gas is burned, pollutants are released into the atmosphere through the flare stack, so there is a need for an environmentally friendly solution that can generate energy using flare gas while reducing pollutant emissions.

[0008] Accordingly, a Flare Gas Recovery System is being applied to conventional flare systems to recover and recycle flare gas. The Flare Gas Recovery System can capture flare gas before it is transferred to the flare stack and recycle it as fuel or raw material, which is very useful in that it can protect the environment, reduce operating costs of the flare system, and reduce cost losses due to gas emissions.

[0009] For example, one method of such flare gas recovery systems involves compressing the flare gas and using it as fuel for a steam-generating boiler. The recovered gas is then mixed with existing boiler fuel to meet the boiler's required heat output. In this case, because the flare gas emitted from the petrochemical plant is subject to severe hunting due to the characteristics of the batch process, the amount of recovered gas is inconsistent, resulting in a large amount of external boiler fuel being input. Consequently, there is a problem where many troubles occur in boiler operation due to instability in controlling the fuel input amount.

[0010] Accordingly, there is a need to develop technology that can prevent the constant discharge of hydrocarbons through the flare stack by injecting the flare gas recovered through the flare gas recovery system as boiler fuel, while simultaneously stabilizing boiler operation by consistently supplying the boiler fuel recovered from the flare gas.

[0011] The problem to be solved in this disclosure is to provide a flare gas recovery method that can ensure operational stability by controlling the amount of fuel supplied to a steam boiler at a constant level even under irregular gas discharge conditions in a flare gas recovery system, in order to solve the problem mentioned in the background technology of the invention.

[0012] However, the problems that this invention seeks to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0013] According to one embodiment of the present disclosure for solving the above problem, the present disclosure provides a flare gas recovery method comprising: a step of supplying flare gas to a compressor to recover compressed gaseous fuel; a step of supplying the compressed gaseous fuel to an absorption tower to absorb hydrocarbon fuel contained in the gaseous fuel into an absorbent; a step of supplying the absorbent in which the hydrocarbon fuel has been absorbed to a degassing tower to volatilize and separate the hydrocarbon fuel absorbed by the absorbent; and a step of storing the hydrocarbon fuel separated in the degassing tower in a liquid state in a storage tank.

[0014] According to the flare gas recovery method of the present disclosure, by using flare gas that is burned and discarded in a conventional flare system as fuel for a boiler to produce steam, an environmentally friendly system can be constructed, and the boiler fuel supply flow rate can be maintained constant even under conditions where the flare gas is discharged in inconsistent amounts, thereby ensuring boiler operation stability.

[0015] The effects obtainable from this invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which this disclosure pertains from the description below.

[0016] FIG. 1 is a flare gas recovery process diagram according to one embodiment of the present disclosure.

[0017] Figure 2 is a conventional flare gas recovery process diagram according to a comparative example.

[0018] Terms and words used in the description and claims of this disclosure shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical idea of ​​this disclosure, based on the principle that the inventor may appropriately define the concept of the terms to best describe his invention.

[0019] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.

[0020] The singular form of the noun corresponding to the item may include one or more of the said item unless the relevant context clearly indicates otherwise.

[0021] In the present disclosure, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0022] The term "and / or" includes a combination of multiple related described components or any of the multiple related described components.

[0023] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish a component from another component and do not limit the components in other aspects (e.g., importance or order).

[0024] In addition, terms such as 'front,' 'rear,' 'top,' 'bottom,' 'side,' 'left,' 'right,' 'top,' and 'bottom' used herein are defined based on the drawings, and the shape and location of each component are not limited by these terms.

[0025] Terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this disclosure, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0026] When it is said that a component is "connected," "combined," "supported," or "in contact" with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.

[0027] When it is said that a component is located "on" another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.

[0028] Additionally, terms such as "about," "substantially," etc., as used herein are used to mean at or near the numerical values ​​where inherent manufacturing and material tolerances are presented in the stated meanings, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosed content where precise or absolute numerical values ​​are mentioned to aid in understanding the present disclosure.

[0029] As used herein, the term 'stream' may refer to the flow of fluid within a process, and may also refer to the fluid itself flowing within the piping. Specifically, the stream may simultaneously refer to the fluid itself flowing within the piping connecting each device and the flow of the fluid. Additionally, the fluid may include one or more components among gas, liquid, and solid.

[0030] Unless otherwise specified, the term 'upper' as used herein refers to a point at a height of 0% to 20% downward from the top of the device, and specifically may refer to the top (top of the tower). Additionally, the term 'lower' refers to a point at a height of 80% to 100% downward from the top of the device, and specifically may refer to the bottom (bottom of the tower).

[0031] In the present disclosure, the term "C#", where "#" is a positive integer, represents any hydrocarbon having # carbon atoms. For example, the term "C20" represents a hydrocarbon compound having 20 carbon atoms.

[0032] As used herein, “pressure” refers to gauge pressure measured relative to atmospheric pressure.

[0033] Meanwhile, in the present disclosure, regarding devices such as absorption towers and degassing towers, the term "operating temperature" of the device may refer to the lower temperature of the device unless otherwise specified. Likewise, the term "operating pressure" of the device may refer to the upper pressure of the device unless otherwise specified.

[0034]

[0035] A flare gas recovery method according to one embodiment of the present disclosure comprises: a step of supplying flare gas to a compressor to recover compressed gaseous fuel; a step of supplying the compressed gaseous fuel to an absorption tower to absorb hydrocarbon fuel contained in the gaseous fuel into an absorbent; a step of supplying the absorbent in which the hydrocarbon fuel has been absorbed to a degassing tower to volatilize and separate the hydrocarbon fuel absorbed by the absorbent; and a step of storing the hydrocarbon fuel separated in the degassing tower in a liquid state in a storage tank.

[0036] A flare gas recovery method according to the present disclosure comprises a compression process, an absorption process, a degassing process, and a condensation process. More specifically, it comprises compressing flare gas discharged from a petrochemical process through a compressor, and storing the compressed vapor in a liquid state in a storage tank after passing through an absorption-degassing-condensation process.

[0037] More specifically, in the absorption process described above, an absorbent that absorbs only hydrocarbon composition is introduced to absorb the hydrocarbon components within the compressed steam fuel, and then only the hydrocarbon fuel is flashed through a degassing process to separate it from the absorbent, and the separated absorbent can be reused in the absorption process. Additionally, the flashed hydrocarbon fuel can be liquefied through a condenser and stored in a storage tank in a liquid state.

[0038] Furthermore, the liquid hydrocarbon fuel stored in the storage tank can serve to supplement the insufficient fuel supply flow to the steam boiler when flare gas emissions from the petrochemical plant are low. Through this, even if the amount of flare gas emitted from the petrochemical plant changes, the fuel supply flow to the steam boiler can be supplemented using the liquid hydrocarbon fuel stored in the tank, thereby maximizing the operational stability of the steam boiler. Accordingly, when the supply of gaseous fuel to the steam boiler becomes insufficient due to a decrease in the amount of flare gas emitted from the petrochemical plant, the additional use of external fuel can be prevented, thereby minimizing unnecessary fuel consumption and atmospheric emissions of flare gas. In this way, the steam generated from the steam boiler can be supplied to the petrochemical plant as a heat source.

[0039] Hereinafter, a flare gas recovery method according to the present disclosure will be described in detail step by step with reference to the drawings.

[0040] FIG. 1 is a schematic diagram of a flare gas recovery process according to one embodiment of the present disclosure.

[0041] Referring to FIG. 1, the flare gas (1) can be separated into gas and liquid in a knockout (KO) drum (10). Specifically, a portion of the flare gas separated into gas and liquid in the knockout drum (10) can be branched and supplied to the compressor (100), and the remainder can be supplied to the flare stack (30).

[0042] The flare gas (1) mentioned above refers to waste gas generated in oil refineries or petrochemical plants, and means a gas that is volatile and combustible. In particular, the flare gas discharged from petrochemical plants may mainly contain hydrocarbons of C8 or lower, specifically C2 to C8, and more specifically C4 to C8, and in some cases may additionally contain a large amount of purge gas (e.g., nitrogen) as an impurity. For example, the flare gas may contain about 5 to 15 weight percent of C2 hydrocarbons and about 15 to 25 weight percent of C4 hydrocarbons, but is not limited thereto. A flare system is operated for the purpose of incinerating waste gas generated in such petrochemical plants and excessive gas caused by unexpected situations during plant operation.

[0043] More specifically, the flare system refers to a set of facilities for collecting hazardous materials (flammable gas, flammable material, toxic material, etc.) generated due to abnormal (emergency) situations such as leakage, fire, operational change, or facility failure in reactors, vessels, tanks, safety valves, etc., and safely burning and discharging the generated hazardous materials into the atmosphere. For example, the flare system may generally include facilities such as a flare header, a knockout drum (10), a sealing drum (20), and a flare stack (30).

[0044] Here, the flare header refers to a main pipe installed to collect gas and liquid discharged from a petrochemical plant in groups and send them to a flare stack (30) or compressor (100).

[0045] Additionally, the knock-out drum (10) is a tank that receives flare gas and can separate and collect the liquid so that the liquid contained in the petrochemical plant effluent does not flow into the flare stack (30) along with the gas. The flare gas separated into gas and liquid in the knock-out drum (10) can be transferred to a compressor (100) through a transfer line or discharged to the flare stack (30) through a sealed drum (20).

[0046] Additionally, the seal drum (20) is provided between the KO drum (10) and the flare stack (30) to prevent the flame generated in the flare stack (30) from propagating backward into the flare system, or to prevent air from being drawn in from the flare stack when a slight vacuum is formed in the flare header. Specifically, the flare header can be maintained at a positive pressure through level control of the seal drum and nitrogen purging to prevent flame backflow from the flare stack.

[0047] In addition, the above-mentioned flare stack (30) is a stack-type incineration tower for burning flare gas and discharging it into the atmosphere.

[0048] Furthermore, the flare gas recovery system incorporates a process for recovering and reusing flare gas in the flare system described above. Specifically, when hazardous materials generated in a petrochemical plant are introduced into a KO drum (10) through a flare header, the gas and liquid are separated in the KO drum, and the separated flare gas is compressed through a compressor (100) and used as fuel for a boiler (500), or, if necessary, burned in a flare stack (30).

[0049] For example, Figure 2 is a process diagram of a conventional flare gas recovery system, which aims to reduce atmospheric emissions and lower costs by recovering and recycling hydrocarbons that are constantly being emitted within the process. Flare gas can be recovered as fuel or raw material after compression through a compressor, but if it contains impurities that are difficult to remove, it is mainly recovered as fuel.

[0050] Referring to FIG. 1, at least a portion of the gas-liquid separated flare gas from the KO drum (10) can be supplied to a compressor (100) to recover compressed gaseous fuel. By compressing the gaseous fuel, the efficiency of transfer to a downstream process and absorption in the absorption tower (200) described later can be increased.

[0051] At this time, the compressor may be a liquid-seal type compressor. If a dry-type compressor is used as the compressor, a process shutdown may occur due to the generation of popcorn polymer in the downstream piping or device.

[0052] The compressor (100) can be operated under a pressure of 1 bar.g or higher, preferably 1 to 3 bar.g, more preferably 2 to 3 bar.g. If the operating pressure of the compressor is lower than the above range, a decrease in the performance of the absorption facility may occur, and if the operating pressure of the compressor is higher than the above range, excessive power consumption may occur.

[0053] Meanwhile, as shown in FIG. 1, a valve may be provided in the piping between the KO drum (10), the sealing drum (20), and the compressor (100), i.e., the flare head. In this case, a Fast Opening Valve (FOV) may be used as the valve. When urgently discharging flare gas in a petrochemical plant, if the gas flow to the flare gas recovery system (process) is not quickly changed to the flare stack (30), a process shutdown may occur.

[0054] According to one embodiment, the compressor (100) can compress a flare gas (1) at an atmospheric pressure level by pressurizing it to a pressure of 1 bar.g or more, preferably 1 to 3 bar.g, and more preferably 2 to 3 bar.g. By compressing the flare gas (1) to the above range, it can be transferred to a downstream process and the absorption performance targeted in the absorption process can be achieved.

[0055] Referring to FIG. 1, all or part of the gaseous fuel (2) compressed in the compressor can be supplied to an absorption tower (200) to absorb the hydrocarbon fuel contained in the gaseous fuel into an absorbent (A).

[0056] According to one embodiment, the gaseous fuel (2) compressed in the compressor (100) can be branched so that a portion is supplied to the absorption tower (200) and the remainder (2') is supplied to the steam boiler (500). Here, the compressed gaseous fuel and the externally supplied fuel (B) can be mixed and used in the steam boiler (500) to match the amount of heat required for steam generation, and in some cases, the liquid hydrocarbon fuel (3) supplied from the storage tank (400) described later can also be mixed and used.

[0057] According to one embodiment, the absorption tower (200) can be operated under a pressure of 1 to 3 bar.g, preferably 2 to 3 bar.g, and a temperature of 5 to 25°C, preferably 5 to 15°C. When the above operating temperature and pressure are satisfied, a flare gas recovery rate of 95% or more can be achieved. More specifically, as the operating pressure of the absorption tower (200) increases and the operating temperature decreases, the absorption rate of hydrocarbon fuel can be improved.

[0058] The above hydrocarbon fuel may include C4 or higher hydrocarbons, specifically C4 to C8 hydrocarbons. If the above hydrocarbon fuel includes C3 or lower hydrocarbons, the condensation efficiency may decrease and the energy consumption during condensation may increase. Specifically, C3 or lower hydrocarbons contained in the compressed gaseous fuel (2) may be re-discharged to the flare header through the top of the absorption tower along with nitrogen.

[0059] The absorbent (A) may include hydrocarbons with a C10 or higher concentration, specifically hydrocarbons with a C10 to C20 concentration. For example, the absorbent (A) may include kerosene (C10 to C12), but is not limited thereto. When hydrocarbons with a C9 or lower concentration are used as the absorbent, the flare gas absorption performance may be reduced.

[0060] Referring to FIG. 1, the absorbent in which the hydrocarbon fuel has been absorbed can be supplied to a degassing tower (300) to volatilize and separate the hydrocarbon fuel absorbed by the absorbent.

[0061] More specifically, the hydrocarbon fuel may be discharged in a gaseous state from the top of the degassing tower (300), and the absorbent (A) may be discharged in a liquid state from the bottom of the degassing tower (300).

[0062] According to one embodiment, the degassing tower (300) can be operated at a temperature of 20 to 40°C and a pressure of -0.5 bar.g or less (high vacuum). By satisfying the operating temperature and pressure conditions of the degassing tower (300), the separation of the absorbent and the hydrocarbon fuel can be performed smoothly, and in detail, the recovery rate of the hydrocarbon fuel can be increased due to an increase in the flow rate of the degassing steam.

[0063] In addition, the upper discharge stream of the degassing tower (300) containing the above-mentioned gaseous hydrocarbon fuel can be supplied to a compressor (not shown) to compress it to a pressure of 2 to 3 bar.g and then supplied to a condenser (350) to be described later. By compressing and then condensing the upper discharge stream of the degassing tower, the condensation efficiency can be increased.

[0064] Furthermore, the gaseous hydrocarbon fuel separated from the above degassing tower (300) can be condensed into a liquid state through a condenser (350) for stable storage, and the liquefied hydrocarbon fuel can be transferred to a storage tank (400) to be described later for storage. For example, the gaseous hydrocarbon fuel before condensation may have a pressure of 2 to 3 bar.g and a temperature of about 40°C, and the liquid hydrocarbon fuel after condensation may have a pressure of 2 to 3 bar.g and a temperature of about 20°C or lower.

[0065] Meanwhile, the absorbent (A) separated in the degassing tower (300) can be recovered and reused in the absorption tower (200). By recovering and reusing the absorbent (A), process costs can be reduced.

[0066] Referring to FIG. 1, the hydrocarbon fuel separated from the degassing tower (300) can be stored in a liquid state in a storage tank (400).

[0067] At this time, the internal temperature of the storage tank (400) can be maintained at 30°C or lower, specifically between 5°C and 30°C. If the internal temperature of the storage tank exceeds the above range, dimers may be generated due to self-polymerization of hydrocarbon fuel, which may reduce efficiency, and additional waste gas may be generated due to degassing.

[0068] According to one embodiment, the hydrocarbon fuel (3) stored in liquid form can be supplied to the steam boiler (500). More specifically, the liquid hydrocarbon fuel (3) can be used by co-combustion with an external supply fuel (B) according to the required heat amount required by the steam boiler (500), and in some cases, the compressed gaseous fuel (2') supplied by part branching from the compressor (100) can also be used by co-combustion. Through this, the total fuel supply flow rate supplied to the steam boiler (500) can be kept constant while maintaining a constant supply amount of the external supply fuel (B), thereby improving the shutdown of the steam boiler, and accordingly, the operational stability of the steam boiler can be secured and the steam supply stability can be improved.

[0069] Meanwhile, the sum of the supply flow rate of the compressed gaseous fuel (2') and the supply flow rate of the liquid stored hydrocarbon fuel (3) can be kept constant. Accordingly, the total fuel supply flow rate supplied to the steam boiler (500) can be kept constant while maintaining the supply amount of the external supply fuel (B) at a constant level, thereby improving the shutdown of the steam boiler that may occur due to unstable fuel supply, and thereby improving the steam supply stability by ensuring the operational stability of the steam boiler.

[0070] Although the flare gas recovery method according to the present disclosure has been described and illustrated in the drawings above, the description and drawings above describe and illustrate only the essential components for understanding the present disclosure, and processes and devices not separately described and illustrated in addition to the processes and devices described and drawings above may be appropriately applied and utilized to implement the flare gas recovery method according to the present disclosure.

[0071]

[0072] The present disclosure will be explained in more detail below through examples. However, the following examples are intended to explain the present disclosure more specifically, and the scope of the present disclosure is not limited by the following examples.

[0073] [Example]

[0074] Comparative example

[0075] Figure 2 is a process diagram of a conventional flare gas recovery system. The purpose of a conventional flare gas recovery system is to reduce atmospheric emissions by recovering hydrocarbon gas that is constantly discharged within the process and to reduce costs by recycling it as fuel.

[0076] Specifically, referring to FIG. 2, flare gas (1) discharged from a petrochemical plant has its liquid removed through gas-liquid separation in a KO drum (10), some of which is compressed to 2 bar.g in a compressor (100) and supplied to a steam boiler (500) as gaseous fuel (2), and the rest is incinerated through a sealed drum (20) and a flare stack (30).

[0077] As the flare system was the final destination for gas emissions, severe batch hunting occurred. Specifically, the calorific value of flare gas emissions from the petrochemical plant averaged around 70 Gcal / h, and hunting ranges of 10 to 100 Gcal / h frequently occurred. Due to such irregular flare gas emissions, additional external fuel (B) supplied to the steam boiler (500) was used to generate consistent steam, resulting in an annual loss of approximately 16 billion won. Furthermore, the unstable supply of fuel caused problems with the steam boiler, leading to frequent shutdowns and a decrease in steam supply stability.

[0078]

[0079] Examples

[0080] As illustrated in FIG. 1, in this embodiment, an absorption-degassing-storage process is configured at the downstream end of the compressor (100) of a conventional flare gas recovery system, consisting of an absorption tower (200), a degassing tower (300), a condenser (350), and a storage tank (400), thereby improving the method of sending a portion of the hydrocarbon vapor recovered by the compressor (100) to the process to be stored in a liquid state and then supplied to a steam boiler (500) when necessary.

[0081] Specifically, referring to FIG. 1, flare gas (1) discharged from a petrochemical plant has its liquid removed through gas-liquid separation in a KO drum (10), some of which is compressed to 2 bar.g in a compressor (100) and supplied to a steam boiler (500) as gaseous fuel, and the rest is incinerated through a sealed drum (20) and a flare stack (30).

[0082] More specifically, when the flare gas emission amount is high, the compressed gaseous fuel (2) is diverted so that a portion (2') is supplied to a steam boiler (500), and the remainder is fed into an absorption tower (200) to absorb hydrocarbon components in the gaseous fuel into kerosene (C10 to C12), which is an absorbent (A). Then, the hydrocarbon components in the gaseous fuel absorbed by the absorbent are volatilized in a degassing tower (300) to separate the absorbent (A) from the hydrocarbon fuel, and the hydrocarbon fuel is condensed into a liquid state in a condenser (350) and stored in a storage tank (500). At this time, the internal temperature of the storage tank is maintained at 20 to 30°C, and the absorbent (A) separated and recovered from the degassing tower (300) is reused in the absorption tower (200).

[0083] Meanwhile, the hydrocarbon fuel (3) stored in a liquid state in a storage tank (500) through the above absorption-degassing-storage process was supplied to a steam boiler (500) when the calorific value of the flare gas was low, thereby allowing the required amount of fuel to be supplied consistently without additional input of external fuel (B).

[0084] As a result, the additional use of external fuel (B) was reduced to an annual level of 1 billion won, and the shutdown of the steam boiler was improved, which improved the stability of the steam supply.

[0085] Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and those skilled in the art will understand that various changes and modifications are possible within the scope and concept of the claims set forth below.

Claims

1. A step of supplying flare gas to a compressor to recover compressed gaseous fuel; A step of supplying the above-mentioned compressed gaseous fuel to an absorption tower to absorb the hydrocarbon fuel contained in the above-mentioned gaseous fuel into an absorbent; A step of supplying the absorbent in which the hydrocarbon fuel has been absorbed to a degassing tower to volatilize and separate the hydrocarbon fuel absorbed by the absorbent; and A flare gas recovery method comprising the step of storing the hydrocarbon fuel separated in the above degassing tower in a liquid state in a storage tank.

2. In Paragraph 1, A flare gas recovery method further comprising branching the gaseous fuel compressed in the above compressor to supply a portion to the above absorption tower and the remainder to the steam boiler.

3. In Paragraph 1, A flare gas recovery method comprising supplying the above-mentioned liquid hydrocarbon fuel stored to a steam boiler.

4. In Paragraph 1, A flare gas recovery method in which the above hydrocarbon fuel comprises C4 to C8 hydrocarbons.

5. In Paragraph 1, A flare gas recovery method in which the absorbent comprises C10 to C20 hydrocarbons.

6. In Paragraph 1, A flare gas recovery method comprising recovering the absorbent from the above degassing tower and reusing it in the above absorption tower.

7. In Paragraph 1, Flare gas recovery method, wherein the above compressor is a liquid-hole type compressor.

8. In Paragraph 1, A flare gas recovery method in which the above compressor is operated under a pressure of 1 to 3 bar.g.

9. In Paragraph 1, A flare gas recovery method comprising condensing and liquefying gaseous hydrocarbon fuel separated in the above degassing tower and then storing it in the above storage tank.

10. In Paragraph 1, A flare gas recovery method in which the internal temperature of the storage tank is maintained at 5 to 30℃.

11. In Paragraph 1, The above flare gas is gas-liquid separated in a knockout drum, and A flare gas recovery method comprising branching off a portion of the gas-liquid separated flare gas from the knockout drum and supplying it to the compressor, and supplying the remainder to the flare stack.

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