CN211799416U

CN211799416U - LNG mill amine flash distillation gas recovery system

Info

Publication number: CN211799416U
Application number: CN201922489109.7U
Authority: CN
Inventors: 吴德平; 于海娟; 阳丹; 王雨生
Original assignee: China Natural Gas Guangyuan Co ltd
Current assignee: China Natural Gas Guangyuan Co ltd
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2020-10-30
Anticipated expiration: 2029-12-31

Abstract

The utility model provides a LNG mill amine flash distillation gas recovery system belongs to liquefied natural gas production and processing technical field. The system comprises an amine absorption tower and an amine flash tank connected with the amine absorption tower, wherein a flash gas outlet of the amine flash tank is provided with a first branch pipe connected with a torch, and a first pressure regulating valve is arranged on the first branch pipe; and a flash gas outlet of the amine flash tank is also provided with a second branch pipe which is parallel to the first branch pipe, the second branch pipe is connected with a fuel gas main pipe, and a second pressure regulating valve and a filtering separator are arranged on the second branch pipe. The utility model discloses flash distillation gas outlet at amine flash tank sets up the second bypass pipe, filters the flash gas that produces, dehydration, then arranges to the fuel gas house steward as fuel gas recycle, has effectively avoided the waste of fuel gas, has improved economic benefits, has reduced environmental pollution.

Description

LNG mill amine flash distillation gas recovery system

Technical Field

The utility model relates to a liquefied natural gas production and processing technology field especially relates to a LNG mill amine flash distillation gas recovery system.

Background

In the process of producing Liquefied Natural Gas (LNG), the amine flash tank mainly has the function of a device for flashing hydrocarbon substances dissolved in the rich amine liquid passing through the amine absorption tower to regenerate the rich amine liquid into the lean amine liquid. As shown in figure 1, in the prior production process, flash gas generated by an amine flash tank is discharged to a main pipe of a hot torch through a pipeline and is subjected to torch combustion treatment. In the exploitation process of part of natural gas wells, sampling analysis shows that the content of methane in the flash gas of the amine flash tank is high and can reach about 90 percent, and the flash gas is directly discharged and combusted by adopting the prior art, so that a large amount of fuel waste exists and environmental pollution can be caused. Therefore, it is necessary to recycle this gas.

SUMMERY OF THE UTILITY MODEL

To the technical problem, the utility model aims at providing a LNG mill amine flash distillation gas recovery system, this system set up second bypass pipe in the flash distillation gas export of amine flash tank, and the flash distillation gas that will produce filters, dehydration treatment, then arranges to the fuel gas house steward as fuel gas recycle, has effectively avoided the waste of fuel gas, has improved economic benefits, has reduced environmental pollution.

In order to achieve the above purpose, the technical scheme of the utility model is as follows:

an amine flash gas recovery system of an LNG plant comprises an amine absorption tower and an amine flash tank connected with the amine absorption tower, wherein a flash gas outlet of the amine flash tank is provided with a first branch pipe connected with a torch, and a first pressure regulating valve is mounted on the first branch pipe; and a flash gas outlet of the amine flash tank is also provided with a second branch pipe which is parallel to the first branch pipe, the second branch pipe is connected with a fuel gas main pipe, and a second pressure regulating valve and a filtering separator are arranged on the second branch pipe.

Further, the second pressure regulating valve is installed in front of an air inlet of the filter separator, and a gas phase outlet of the filter separator is connected with the fuel gas main pipe.

Further, a first pressure gauge is installed at an air inlet of the filtering separator, and a second pressure gauge is installed at a gas phase outlet of the filtering separator.

Further, the operating pressure of the amine flash tank is greater than the operating pressure of the fuel gas main.

Further, the working pressure of the amine flash tank is 0.35MPa, and the pressure of the fuel gas main pipe is 0.3 MPa.

Further, the flash evaporation capacity of the amine flash tank is more than or equal to 30 standard square/hour.

Further, a gas flowmeter is installed on the second branch pipe and located between the filtering separator and the fuel gas main pipe.

Compared with the prior art, the beneficial effects of the utility model are that:

the utility model discloses add the second by-pass pipe of being connected with the fuel gas main in the flash distillation gas export of amine flash tank, install second air-vent valve and filtering separation ware on the second by-pass pipe, can filter flash distillation gas, the leading-in fuel gas main utilizes as fuel after dehydration. And the first branch pipe is provided with a first pressure regulating valve, and the first pressure regulating valve and the second pressure regulating valve can be opened, closed or flow rate regulated according to production requirements, so that flash steam is discharged to a torch for combustion through the first branch pipe or recycled through the second branch pipe. The recovery system has simple equipment structure and convenient operation, and can effectively recycle the fuel gas in the amine flash evaporation gas. The flash steam can be recovered by about 700 formula every day, the effect can be generated by about 40 ten thousand yuan in annual production, and the economic benefit is remarkable.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of the prior art.

Fig. 2 is a schematic structural diagram of the present invention.

Reference numerals:

1: an amine absorber; 2: an amine flash tank; 21: a flash evaporation gas outlet; 3: a torch; 4: a first branch pipe; 41: a first pressure regulating valve; 5: a first branch pipe; 51: a second pressure regulating valve; 52: a filtration separator; 521: a first pressure gauge; 522: a second pressure gauge; 53: a gas flow meter; 6: a second branch pipe.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

In the description of the present invention, it should be understood that the terms "mounted," "connected," and the like are used in a broad sense, and for example, the terms "mounted," "connected," and "connected" may be fixed, detachable, or integrated; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in fig. 2, the embodiment of the utility model provides a LNG factory amine flash distillation gas recovery system, including amine absorption tower 1, amine flash tank 2, first branch pipe 4, second branch pipe 5, first air-vent valve 41, second air-vent valve 51, filtering separator 52, first manometer 521, second manometer 522, gas flowmeter 53 and torch 6 etc..

The amine absorption tower 1 is connected with the amine flash tank 2, the raw material gas enters the amine absorption tower 1, hydrocarbon substances contained in the raw material gas are absorbed by the solution, the solution is changed into amine-rich liquid, and the amine-rich liquid enters the amine flash tank 2 for flash evaporation, so that the hydrocarbon substances dissolved in the solution are flash evaporated.

The amine flash tank 2 is provided with an amine rich liquid inlet, an amine lean liquid outlet and a flash gas outlet 21. A flash gas outlet 21 of the amine flash tank 2 is connected with a first branch pipe 4 and a second branch pipe 5, and the first branch pipe 4 and the second branch pipe 5 are arranged in parallel. Wherein, the first branch pipe 4 is connected with a torch 3, and the torch 3 is used for emptying the combustible gas discharged in the process of burning, starting the vehicle, normal operation, accident or emergency. The first branch pipe 4 is provided with a first pressure regulating valve 41, and the first pressure regulating valve 41 can open and close the first branch pipe 4 and regulate the flow rate of gas in the first branch pipe 4. The second branch pipe 5 is arranged in parallel with the first branch pipe 4, and the second branch pipe 5 is connected with the fuel gas main pipe 6 and can discharge the amine flash evaporation gas into the fuel gas main pipe 6. The second branch pipe 5 is provided with a second pressure regulating valve 51 and a filtering separator 52, the second pressure regulating valve 51 can open and close the second branch pipe 5, and the gas flow of the second branch pipe 5 is regulated; the filtering separator 52 has a filtering and dehydrating function, and can separate water vapor contained in the amine flash gas from the gas, and filter suspended substances and the like in the gas, so that the combustible gas introduced into the fuel gas header pipe 6 is a dry and clean gas. Therefore, the first pressure regulating valve 41 and the second pressure regulating valve 51 can be opened or closed according to the production condition, and the amine flash steam is controlled to be discharged to the torch 3 for combustion through the first branch pipe 4 or discharged to the fuel gas main pipe 6 for recycling through the second branch pipe 5.

Wherein, the second pressure regulating valve 51 is arranged in front of the air inlet of the filtering separator 52, and the gas phase outlet of the filtering separator 52 is connected with the fuel gas main pipe 6. The second pressure regulating valve 51 can control the amine flash vapor to enter the filtering separator 52.

A first pressure gauge 521 is installed at the air inlet of the filter separator 52, and a second pressure gauge 522 is installed at the gas phase outlet of the filter separator 52. The first pressure gauge 521 can monitor the pressure of the amine flash gas entering the filter separator 52 in the second branch pipe 5 in real time, and the second pressure gauge 522 can monitor the pressure of the gas discharged from the filter separator 52 in the second branch pipe 5 in real time. In operation, the operating condition of the filter separator 52 can be determined based on the difference between the readings of the first pressure gauge 521 and the second pressure gauge 522.

In order to ensure that the amine flash gas can be normally discharged into the fuel gas main pipe 6, and the fuel gas in the fuel gas main pipe 6 cannot reversely flow into the second branch pipe 5, the working pressure of the amine flash tank 2 needs to be greater than the working pressure of the fuel gas main pipe 6. Preferably, the operating pressure of the amine flash tank 2 is set to 0.35MPa, the flash amount is 30 square meters or more per hour, and the pressure of the fuel gas header 6 is set to 0.3 MPa. The amine flash evaporation gas can be ensured to smoothly enter the fuel gas main pipe 6 for recycling, and the normal operation of the boiler connected with the fuel gas main pipe 6 can be ensured. When the flash evaporation amount of the amine flash tank 2 is about 30 standard square/hour, about 700 square of flash evaporation gas can be recovered every day, if the flash evaporation gas is produced all year round, about 40 ten thousand yuan of benefit can be created, and the economic benefit is remarkable.

Preferably, the second branch pipe 5 is provided with a gas flow meter 53, the gas flow meter 53 is positioned between the filter separator 52 and the fuel gas header pipe 6, and can record the gas amount discharged from the gas phase outlet of the filter separator 52 and entering the fuel gas header pipe 6, so as to conveniently, quickly, intuitively and accurately know the amount of the combustible gas to be recycled.

Claims

1. An amine flash gas recovery system of an LNG plant comprises an amine absorption tower (1) and an amine flash tank (2) connected with the amine absorption tower (1), wherein a flash gas outlet (21) of the amine flash tank (2) is provided with a first branch pipe (4) connected with a torch (3), and the system is characterized in that a first pressure regulating valve (41) is installed on the first branch pipe (4); and a flash gas outlet (21) of the amine flash tank (2) is also provided with a second branch pipe (5) which is parallel to the first branch pipe (4), the second branch pipe (5) is connected with a fuel gas main pipe (6), and a second pressure regulating valve (51) and a filtering separator (52) are arranged on the second branch pipe.

2. The LNG plant amine flash gas recovery system of claim 1, wherein the second pressure regulating valve (51) is installed before an air inlet of the filter separator (52), and a gas phase outlet of the filter separator (52) is connected to the fuel gas header pipe (6).

3. The LNG plant amine flash gas recovery system of claim 2, wherein a first pressure gauge (521) is installed at an air inlet of the filter separator (52), and a second pressure gauge (522) is installed at a gas phase outlet of the filter separator (52).

4. LNG plant amine flash gas recovery system according to claim 1 or 3, characterized in that the operating pressure of the amine flash drum (2) is greater than the operating pressure of the fuel gas main (6).

5. LNG plant amine flash gas recovery system according to claim 4 characterized in that the operating pressure of the amine flash drum (2) is 0.35MPa and the fuel gas header (6) pressure is 0.3 MPa.

6. LNG plant amine flash gas recovery system according to claim 5, characterized in that the flash volume of the amine flash drum (2) is equal to or more than 30 sq.

7. LNG plant amine flash gas recovery system according to claim 1 or 6, characterized in that a gas flow meter (53) is mounted on the second by-pass pipe (5), the gas flow meter (53) being located between the filter separator (52) and the fuel gas main (6).