CN112204253A

CN112204253A - Apparatus and method for compressing low pressure gas

Info

Publication number: CN112204253A
Application number: CN201980036393.2A
Authority: CN
Inventors: H·古达查
Original assignee: Engie SA
Current assignee: Engie SA
Priority date: 2018-05-28
Filing date: 2019-05-24
Publication date: 2021-01-08
Also published as: EP3803118A1; PT3803118T; EP3803118B1; US20210207591A1; WO2019229339A1; FR3081518B1; FR3081518A1

Abstract

An apparatus (100) for compressing a low pressure gas, the apparatus comprising: -at least one compression chamber (105) comprising: -an inlet (110) for low pressure gas, -an outlet (115) for high pressure gas, -an inlet (120) for fluid, -an outlet (125) for fluid, and-a piston (130) located between the gas inlet and outlet and the fluid inlet and outlet, one face of the piston being at the gas inlet and outlet sides, the other face of the piston being at the fluid inlet and outlet sides; -a fluid moving device (135) on a fluid circuit connecting the fluid inlet and the fluid outlet of the compression chamber; and-means (165) for measuring the pressure of the gas inside the compression chamber and a circuit (160) for recirculating the gas to the inlet of the compression chamber when the measured pressure is less than a predetermined limit value.

Description

Apparatus and method for compressing low pressure gas

Technical Field

The present invention relates to an apparatus and method for compressing low pressure gas. It is especially suitable for compressing marsh gas.

Background

Collecting the available low pressure gas to compress it to high pressure presents technical and economic difficulties. Various compressor techniques exist to perform such compression. These various techniques are very energy intensive.

To obtain the required compression ratio, the compressor may comprise a plurality of compression stages with intermediate cooling, which makes the method more complicated.

The compressors may be different types of compressors, and the configuration may be selected from:

positive displacement compressors (reciprocating or screw compressors) which can provide intermittent power flow. In these techniques, the gas is compressed to a small volume, thereby increasing the pressure.

Dynamic compressors (centrifugal or axial compressors) which can provide a continuous power flow. In a centrifugal compressor, kinetic energy is converted into potential energy, thereby increasing the pressure of the fluid.

Positive displacement compressors require frequent maintenance, can only operate at low flow rates, run short, and consume large amounts of energy.

Dynamic compressors are sensitive to load composition and flow variations, have a limited compression ratio, and are energy intensive.

Disclosure of Invention

The present invention aims to remedy all or part of these disadvantages.

To this end, according to a first aspect, the invention envisages a device for compressing a gas at low pressure, the device comprising:

-at least one compression chamber comprising:

-an inlet for a gas at low pressure,

-an outlet for high-pressure gas,

-an inlet for a fluid,

-an outlet for the fluid, and

-a piston located between the gas inlet and outlet and the fluid inlet and outlet, one face of the piston being at the gas inlet and outlet sides and the other face of the piston being at the fluid inlet and outlet sides;

-a fluid moving device arranged on a fluid circuit connecting the fluid inlet and the fluid outlet of the compression chamber; and

-means for measuring the pressure of the gas inside the compression chamber and a circuit for recirculating the gas to the inlet of the compression chamber when the measured pressure is less than a predetermined limit value.

Due to these arrangements, the energy cost of compressing the gas is reduced. An increase in fluid pressure within the compression chamber causes the piston to move and compress the gas. And compressing fluid uses less energy than compressing gas.

In some embodiments, the apparatus that is the subject of the present invention includes a check valve configured to prevent backflow of gas in the gas inlet.

These embodiments make it possible to prevent gas from flowing back towards the compression chamber inlet.

In some embodiments, the apparatus that is the subject of the present invention includes a fluid holding valve configured to hold fluid in the compression chamber.

These embodiments make it possible to provide an improved compression of the gas by limiting the outlet of the fluid to a defined pressure.

In some embodiments, the displacement device is configured such that the pressure of the exhaust fluid is between 30 and 70 bar.

In some embodiments, the moving device is a pump.

In some embodiments, the device as subject of the invention comprises a plurality of compression chambers in series for the fluid circuit, the fluid outlet of one compression chamber being connected to the fluid inlet of another compression chamber.

These embodiments make it possible to share the fluid circuit.

In some embodiments, the apparatus as subject of the invention comprises a plurality of compression chambers for gas in parallel, each compression chamber comprising a gas inlet and outlet independent of any other compression chamber.

These embodiments make it possible to compress a plurality of gases simultaneously.

In some embodiments, the device that is the subject of the invention comprises means for measuring the pressure of the gas inside the compression chamber and means for opening the gas outlet of the compression chamber according to the measured pressure.

According to a second aspect, the invention envisages a method for compressing a low-pressure gas, comprising:

-a step of feeding a low-pressure gas into the compression chamber;

-a step of feeding a fluid into the compression chamber;

-a step of moving a piston, the piston being located between the gas inlet and outlet and the fluid inlet and outlet, one face of the piston being at the gas inlet and outlet sides and the other face of the piston being at the fluid inlet and outlet sides;

-a step of outputting high pressure gas from the compression chamber;

-a step of outputting the fluid from the compression chamber;

-a step of moving a fluid on a fluid circuit connecting a fluid inlet and a fluid outlet of the compression chamber; and

-a step of measuring the pressure of the gas in the compression chamber and a step of recirculating the gas to the inlet of the compression chamber when the measured pressure is less than a predetermined limit value.

Since certain objects, advantages and features of the method, which is the subject of the present invention, are similar to those of the device, which is the subject of the present invention, further description is omitted here.

Drawings

Further advantages, objects and particular features of the invention will become apparent from the following non-limiting description of at least one particular embodiment of the apparatus and method which are the subject of the invention, with reference to the accompanying drawings included in the appendix, in which:

figure 1 schematically shows a first particular embodiment of the device that is the subject of the present invention;

figure 2 schematically shows a second particular embodiment of the device that is the subject of the present invention; and

figure 3 schematically shows, in the form of a logic diagram, a series of specific steps of the method that is the subject of the invention.

Detailed Description

The present description is given in a non-limiting manner, in which each feature of an embodiment can be combined in an advantageous manner with any other feature of any other embodiment.

It is noted that the drawings are not to scale.

Note that here, the term "gas" includes natural gas, biogas and syngas.

Note that here, the term "fluid" refers to any fluid. Preferably, the use of an incompressible viscous fluid is envisaged.

Fig. 1 shows a schematic diagram of an embodiment of a device 100 as subject of the invention, not to scale. The apparatus 100 for compressing low-pressure gas includes:

at least one compression chamber 105 comprising:

an inlet 110 for low-pressure gas,

outlet 115 for high-pressure gas

An inlet 120 for a fluid,

an outlet 125 for the fluid, and

a piston 130, which is located between the gas inlet and the outlet on the one hand and the fluid inlet and the outlet on the other hand;

a fluid moving device 135 located on a fluid circuit connecting the fluid inlet and the fluid outlet of the compression chamber; and

means 165 for measuring the pressure of the gas inside the compression chamber and a circuit 160 for recirculating the gas to the inlet of the compression chamber when the measured pressure is less than a predetermined limit value.

The compression chamber 105 is for example formed by an impermeable wall surrounding a given volume in which the piston 130 operates. Preferably, the only openings in the impermeable wall are:

an inlet 110 for low pressure gas;

an outlet 115 for high pressure gas;

an inlet 120 for a fluid; and

an outlet 125 for the fluid.

The compression chamber 105 may have, for example, the inner volume of a cylinder. The term "cylinder" refers to a cylinder that rotates about an axis.

However, the internal volume of the compression chamber 105 may be of any type that allows the piston 130 to move. This generally means having a constant cross-section with respect to the axis of motion of the piston 130.

The piston 130 forms an impermeable separation between the fluid and the gas. The compression chamber 105 is configured to allow the pressure of the gas to increase to, for example, over 50 bar, 100 bar or 200 bar. Preferably, the pressure of the gas entering the compression chamber 105 exceeds 3 or 4 bar, and preferably exceeds 7 bar.

Each of the elements in the gas inlet 110 and outlet 115 and the fluid inlet 120 and outlet 125 is, for example, an opening in the compression chamber 105. Depending on the nature of these elements, each of these

elements

110, 115, 120 and 125 is preferably associated with a line for conveying gas or fluid.

In some preferred variations, at least one element of the gas inlet 110 and outlet 115 and the fluid inlet 120 and outlet 125 is equipped with a check valve 140. The check valve 140 may, for example, be mounted directly on or downstream of the opening of the compression chamber 105, for example at the location of the line associated with the element in question.

Such a check valve 140 is, for example, configured to prevent gas in the gas inlet 110 from flowing back.

In some variations, the at least one check valve 140 is replaced by a valve or any other type of device that can prevent the passage of gas or fluid, depending on the associated elements.

In some variations, the apparatus 100 includes a fluid retention valve 145 configured to retain fluid in the compression chamber 105. The valve 145 may be of any type known to those skilled in the art and is adapted to the operating pressure in the fluid circuit 150. The valve 145 may be mounted directly on the outlet of the compression chamber 105 or along the circuit 150.

Note that each of the elements of the gas inlet 110 and outlet 115 and the fluid inlet 120 and outlet 125 may be formed by a plurality of sub-elements of the same type that participate in the same function. For example, the gas inlet 110 may be constituted by a plurality of openings in the compression chamber 105, each opening being supplied by a separate line or by a line common to the other openings.

The piston 130 is, for example, an impermeable surface or membrane that moves along the axis of the compression chamber 105. The piston 130 may be guided by a shaft fixed to one or the other moving end of the piston 130.

The movement device 135 may be of any type that allows fluid to move in a fluid circuit. The selection of the displacement device 135 depends on the size of the loop 150 and the total pressure drop of the loop 150.

Preferably, the displacement device 135 is configured such that the pressure of the outgoing fluid is between 30 and 70 bar. However, the device 100 may be compressed at any pressure value, preferably below 300 bar.

Preferably, the moving device 135 is a pump.

In some preferred embodiments, the apparatus 100 as subject of the invention comprises a plurality of compression chambers 105 in series for the fluid circuit 150, the fluid outlet 125 of one compression chamber being connected to the fluid inlet 120 of another compression chamber.

In this variation, the chambers 105 are filled sequentially, starting with the chamber closest to the discharge of the fluid moving device 135. Once the operation is complete, fluid is delivered to the second chamber 105, and so on.

In another variation shown in fig. 2, the chambers 105 are filled simultaneously. This filling is performed, for example, by the main circuit supplying the respective compression chamber 105.

In some preferred embodiments, the apparatus 100 as subject of the invention comprises a plurality of compression chambers 105 in parallel for the gas, each compression chamber comprising a gas inlet 110 and an outlet 115 independent of any other compression chamber.

In some preferred embodiments, the apparatus 100 subject of the invention comprises means 165 for measuring the pressure of the gas inside the compression chamber 105 and a circuit 160 for recirculating the gas to the inlet of the compression chamber when the measured pressure is less than a predetermined limit value.

The pressure measuring device 165 is for example a pressure sensor located inside the compression chamber 105, on the gas side of the piston 130 or on the fluid side of the piston 130.

In some variations, the pressure measurement device 165 is mechanical or electronic and operates by capturing the position of the piston 130 in the chamber. When the piston 130 reaches a predetermined position on its axis of motion, the gas pressure is derived by the measuring means 165.

The predetermined limit value may be set during the design of the apparatus 100 or it may be variable and may be recorded via a central control circuit connected to the apparatus 100 by a wired or wireless control connection.

In some preferred embodiments, the device 100 as subject of the invention comprises means 165 for measuring the pressure of the gas inside the compression chamber 105 and means 170 for opening the compression chamber gas outlet 115 according to the measured pressure.

The opening device 170 belongs to a discharge device, for example. In this example, the discharge device is constructed as both the measuring device 165 and the opening device 170. The exhaust is calibrated to a set pressure.

In some variations, the exhaust valve is opened once the target pressure is reached, and the exhaust valve is closed at a threshold pressure. These pressure standards will be selected by the operator depending on the use.

The operation of the apparatus 100 described with reference to fig. 1 will be better understood with reference to the following description of the method 200 of operation of the apparatus 100.

Fig. 3 schematically shows a logic diagram of certain steps of the method 200 that is the subject of the invention. The method 200 for compressing low pressure gas comprises:

-a step 205 of feeding low pressure gas into the compression chamber;

-a step 210 of feeding fluid into the compression chamber;

a step 215 of moving the piston, the piston being located between the gas inlet and outlet and the fluid inlet and outlet, one face of the piston being at the gas inlet and outlet sides and the other face of the piston being at the fluid inlet and outlet sides;

a step 220 of outputting high-pressure gas from the compression chamber;

-a step 225 of outputting the fluid from the compression chamber;

a step 230 of moving the fluid on a fluid circuit connecting the fluid inlet and the fluid outlet of the compression chamber.

Preferably, the pressure in the compression chamber is initially lower than the pressure in the line delivering gas to the gas inlet of the compression chamber. This can be achieved by pressurizing the gas upstream or by reducing the pressure in the fluid part of the compression chamber.

To achieve this pressure reduction, for example, a valve on the inlet side of the fluid inlet is closed when the displacement device is in operation. This causes the piston to move towards the fluid outlet, which reduces the pressure in the gas part of the compression chamber (whose gas outlet is also closed). Optionally, the gas inlet is also closed.

In the case where only the gas outlet is closed, a suction mechanism that sucks gas through the gas inlet is generated, and the gas portion of the compression chamber is gradually filled. This means that it is not necessary to use a moving device dedicated to the supplied gas in the method 200 that is the subject of the invention.

Regardless of the solution of allowing the gas to enter the compression chamber, once the gas is entered, it finds itself confined in the variable volume of the compression chamber dedicated to the gas.

The moving means 135 is activated so that the fluid portion of the compression chamber is filled with fluid which gradually moves the piston towards the gas outlet, thereby compressing the gas.

Once the desired gas pressure is reached, the gas is released towards the gas outlet of the compression chamber. To facilitate the output of gas, the fluid may continue to circulate to continue movement of the piston until the gas is completely or almost completely exhausted toward the gas outlet.

In order to evacuate the fluid comprised in the fluid portion of the compression chamber, the fluid outlet of the compression chamber is open.

Thus, it can be seen that the suction/compression/discharge cycle of the gas can be produced in the following manner:

-closing the gas outlet,

-closing the fluid inlet and the fluid outlet,

-opening the gas inlet(s),

-opening the fluid outlet and,

-activating the fluid-moving device,

so that the gas is sucked into the compression chamber, following:

-closing the gas inlet(s),

-opening the fluid inlet and/or the fluid outlet,

-closing the fluid outlet,

-activating the fluid-moving device,

so that the gas is compressed, following:

-opening the gas outlet(s),

-activating the fluid-moving device,

thereby allowing the gas to be exhausted.

The method 200, which is the subject of the invention, is carried out, for example, by using one of the

apparatuses

100 or 300, which is the subject of the invention and is described with reference to fig. 1 and 3.

Claims

1. An apparatus (100, 300) for compressing a low-pressure gas, characterized in that it comprises:

-at least one compression chamber (105) comprising:

-an inlet (110) for low pressure gas,

-an outlet (115) for high pressure gas,

an inlet (120) for a fluid,

-an outlet (125) for the fluid, and

-a piston (130) located between the gas inlet and outlet and the fluid inlet and outlet, one face of the piston being at the gas inlet and outlet sides and the other face of the piston being at the fluid inlet and outlet sides;

-a fluid moving device (135) arranged on a fluid circuit connecting the fluid inlet and the fluid outlet of the compression chamber; and

-means (165) for measuring the pressure of the gas inside said compression chamber and a circuit (160) for recirculating the gas to the inlet of the compression chamber when the measured pressure is less than a predetermined limit value.

2. The apparatus (100, 300) of claim 1, comprising a check valve (140) configured to prevent backflow of gas in the gas inlet (110).

3. The apparatus (100, 300) according to one of claims 1 or 2, comprising a fluid retaining valve (140) configured to retain fluid in the compression chamber (105).

4. The apparatus (100, 300) according to any of claims 1 to 3, wherein the moving device (135) is configured such that the pressure of the exhaust fluid is between 30 and 70 bar.

5. The apparatus (100, 300) according to any one of claims 1 to 4, wherein the moving device (135) is a pump.

6. The apparatus (100, 300) of any of claims 1 to 5, comprising a plurality of compression chambers (105) in series for the fluid circuit (150), the fluid outlet (125) of one compression chamber being connected to the fluid inlet (120) of another compression chamber.

7. The apparatus (100, 300) according to any one of claims 1 to 6, comprising a plurality of compression chambers (105) in series for the gas, each compression chamber comprising a gas inlet (110) and outlet (115) independent of any other compression chamber.

8. The device (100, 300) according to any of claims 1 to 7, comprising means (165) for measuring the gas pressure inside the compression chamber (105) and means (170) for opening a compression chamber gas outlet (115) depending on the measured pressure.

9. A method (200) for compressing a low pressure gas, the method comprising:

-a step (205) of feeding a low pressure gas into the compression chamber;

-a step (210) of feeding a fluid into said compression chamber;

-a step (215) of moving a piston, said piston being located between a gas inlet and an outlet and a fluid inlet and an outlet, one face of said piston being on the gas inlet and outlet side and the other face of said piston being on the fluid inlet and outlet side;

-a step (220) of outputting high pressure gas from the compression chamber;

-a step (225) of outputting fluid from the compression chamber;

-a step (230) of moving a fluid on a fluid circuit connecting a fluid inlet and a fluid outlet of the compression chamber; and

-a step (235) of measuring the pressure of the gas inside the compression chamber and a step (240) of recirculating the gas to the inlet of the compression chamber when the measured pressure is less than a predetermined limit value.