A flame fuel cell coupled oil and gas torch combustion system and method

Abstract

The present invention provides an oil and gas flare combustion system and method coupled with a flame fuel cell, comprising a flare burner housing, a micro-mixing burner, a flame fuel cell and a secondary burner; the micro-mixing burner is connected and installed on the upstream side of the bottom of the flare burner housing; the secondary burner is connected and installed on the downstream side of the top gas outlet of the flare burner housing; the interior of the flare burner housing has a cross-section that gradually decreases from bottom to top to form a conical cavity; the flame fuel cell is arranged on the conical inner wall of the conical cavity. Advantages: (1) The flame fuel cell and the flare combustion are creatively combined to achieve efficient and clean utilization of associated gas. (2) By stacking the micro-tubular flame fuel cells in a conical shape, the problems of short fuel residence time and uneven temperature distribution of the existing flame fuel cells are solved, and the power generation capacity can be increased by increasing the number of flame fuel cell layers, thus achieving a modular design.

Description

Technical Field

[0001] The invention belongs to the technical field of offshore oil and gas exploration, and in particular relates to an oil and gas torch combustion system and method coupled with a flame fuel cell. Background Art

[0002] A large amount of associated gas is generated during the production process of offshore oil and gas platforms. The sources mainly include process gas, flash gas, sealing gas and leakage gas. The main component is methane, and there are also small amounts of hydrocarbon gases such as ethane, propane and butane. Associated gas is usually difficult to recover because of its low pressure. It needs to enter the flare system for discharge and combustion to avoid unburned combustible gas or toxic and harmful gases being directly discharged into the atmosphere.

[0003] For a typical offshore oil field, the daily production of associated gas ranges from tens of thousands to hundreds of thousands of cubic meters. In the existing technology, the associated gas is directly burned through the flare system, which causes a lot of energy waste and does not meet the requirements of energy conservation and emission reduction. In the flare combustion system, how to achieve clean and efficient utilization of associated gas is a key issue that needs to be solved at present. Summary of the invention

[0004] In view of the defects in the prior art, the present invention provides an oil and gas torch combustion system and method coupled with a flame fuel cell, which can effectively solve the above problems.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The present invention provides an oil and gas torch combustion system coupled with a flame fuel cell, comprising a torch burner housing (1), a micro-mixing burner (2), a flame fuel cell (3) and a secondary burner (4);

[0007] The upstream side of the bottom of the flare burner housing (1) is connected to the micro-mixing burner (2) and installed; the downstream side of the top gas outlet (1-1) of the flare burner housing (1) is connected to the secondary burner (4) and installed;

[0008] The interior of the flare burner housing (1) has a cross section that gradually decreases from bottom to top to form a conical cavity; the flame fuel cell (3) is arranged on the conical inner wall of the conical cavity.

[0009] Preferably, the flame fuel cell (3) comprises a plurality of fuel cell microtubes (3-1), each of the fuel cell microtubes (3-1) being laid in layers around the circumference of the conical inner wall;

[0010] Each of the fuel cell microtubes (3-1) is arranged obliquely relative to the central axis of the conical cavity; each of the fuel cell microtubes (3-1) has a first air inlet (3-1-1) at the bottom thereof, which is connected to the bottom air inlet (1-2) of the flare burner housing (1); the top of the fuel cell microtube (3-1) extends to a position of the flare burner housing (1) close to the top gas outlet (1-1), and is located upstream of the top gas outlet (1-1), and a first air nozzle (3-1-2) is formed at the top of the fuel cell microtube (3-1); the inner cavity of the fuel cell microtube (3-1) is an air flow channel (3-1-3);

[0011] The tube wall of the fuel cell microtube (3-1) has a three-layer structure, wherein the outer layer is the anode (3-1-4); the inner layer is the cathode (3-1-5); and the middle layer is the electrolyte (3-1-6).

[0012] Preferably, after each of the fuel cell microtubes (3-1) is laid in layers around the conical inner wall in a circumferential direction, a conical flame combustion concentration area (A) is formed in the central area of ​​the conical cavity relative to the central axis.

[0013] Preferably, the micro-mixing burner (2) comprises a micro-tube (2-1), a second air inlet (2-2) and an associated gas fuel inlet (2-3);

[0014] A plurality of microtubes (2-1) are arranged vertically at intervals; the top jet end of each microtube (2-1) faces the conical flame combustion concentration area (A); the bottom of each microtube (2-1) is connected to the associated gas fuel inlet (2-3); and the bottom of the gap between adjacent microtubes (2-1) is connected to the second air inlet (2-2).

[0015] Preferably, the secondary burner (4) comprises a combustion stabilizing blunt body (4-1) and an igniter (4-2); the combustion stabilizing blunt body (4-1) and the igniter (4-2) are arranged in sequence along the gas exhaust flow direction.

[0016] The present invention also provides a torch combustion method of the oil and gas torch combustion system coupled with a flame fuel cell, comprising the following steps:

[0017] Step S1, primary combustion process of the micro-mixing burner (2):

[0018] The associated gas fuel and air enter the micro-mixing burner (2) through the associated gas fuel inlet (2-3) and the second air inlet (2-2) respectively at a flow rate ratio of excess fuel, the associated gas fuel is ejected from the micro-tube (2-1), and the air is ejected from the gaps between the micro-tubes (2-1); the air and the associated gas fuel are premixed on the surface of the micro-mixing burner (2) by setting the air injection direction, thereby forming a large number of rich small flames on the surface of the micro-mixing burner (2), and converting the associated gas fuel into hydrogen and carbon monoxide;

[0019] Step S2, the flame fuel cell (3) performs a process of generating electricity by utilizing the associated gas fuel:

[0020] Step S2.1, air flows in from the first air inlet (3-1-1) at the bottom of the fuel cell micro-tube (3-1), and flows downstream in the air flow channel (3-1-3) in the fuel cell micro-tube (3-1);

[0021] Step S2.2, when the air flows in the air channel (3-1-3), part of the oxygen in the air undergoes an electrochemical reduction reaction with the cathode (3-1-5) of the fuel cell microtube (3-1) to generate O 2- ;

[0022] Step S2.3, O 2- Conducted from cathode (3-1-5) to anode (3-1-4) through electrolyte (3-1-6);

[0023] Step S2.4, after the combustion in step S1, the flame-rich tail gas rich in hydrogen and carbon monoxide contacts the surface of the anode (3-1-4) of the fuel cell microtube (3-1), and under the high temperature heating of the flame, the hydrogen and carbon monoxide react with the O2 transferred to the anode (3-1-4). 2- An electrochemical oxidation reaction occurs, generating electrons;

[0024] Step S2.5, the electrons generated by the anode (3-1-4) are transferred to the cathode (3-1-5) through an external circuit, thereby generating electricity and realizing power generation using associated gas fuel;

[0025] Step S3, the secondary burner (4) performs a secondary combustion process:

[0026] The air ejected from the first air nozzle (3-1-2) at the top of the fuel cell microtube (3-1) is quickly mixed with the incompletely burned associated gas and the combustion exhaust gas, and is ignited by the igniter (4-2) under the action of the combustion stabilizing blunt body (4-1), and stably burns in the form of a lean flame to ensure that the associated gas is fully burned; after the lean secondary combustion, the gas is discharged.

[0027] Preferably, in step S1, the equivalence ratio of the associated gas fuel to air is between 1.3 and 1.5.

[0028] The oil and gas torch combustion system and method coupled with a flame fuel cell provided by the present invention have the following advantages:

[0029] (1) The creative combination of flame fuel cells and flare combustion can achieve efficient and clean utilization of associated gas without occupying space on offshore oil and gas platforms or making large investments.

[0030] (2) By stacking the micro-tube flame fuel cells in a conical shape, the problems of short fuel residence time and uneven temperature distribution in existing flame fuel cells are solved, and the power generation capacity can be increased by increasing the number of flame fuel cell layers, thus achieving a modular design.

[0031] (3) By using a micro-mix burner as the primary burner of the torch, the stability of the rich flame under high associated gas flow rate can be ensured, the rich flame can be prevented from being blown out, and the flame heat release can be made more uniform in the axial direction.

[0032] (4) Through the burner structure design, the air flowing out of the center of the microtube flame fuel cell and the incompletely burned associated gas are quickly mixed, and a secondary burner is constructed through a flame-stabilizing blunt body to achieve complete combustion of the associated gas and avoid the emission of combustibles and toxic gases into the atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic structural diagram of an oil and gas torch combustion system coupled with a flame fuel cell provided by the present invention.

[0034] Figure 2 A cross-sectional view of a fuel cell microtube provided by the present invention. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] The present invention proposes an oil and gas flare combustion system and method coupled with a flame fuel cell, improves the structure of the flame fuel cell, redesigns the flare burner, achieves efficient and clean utilization of associated gas, and improves the burnout rate of combustible gas.

[0037] See also Figure 1 and Figure 2 The present invention proposes an oil and gas torch combustion system coupled with a flame fuel cell, comprising: a torch burner housing 1, a micro-mixing burner 2, a flame fuel cell 3 and a secondary burner 4;

[0038] The upstream side of the bottom of the flare burner housing 1 is connected to a micro-mixing burner 2 and installed; the downstream side of the top gas outlet 1-1 of the flare burner housing 1 is connected to a secondary burner 4 and installed;

[0039] Inside the flare burner housing 1, the cross section gradually decreases from bottom to top to form a conical cavity; the flame fuel cell 3 is arranged on the conical inner wall of the conical cavity.

[0040] The specific structures of the flame fuel cell 3, the micro-mixing burner 2 and the secondary burner 4 are described in detail below:

[0041] (I) Flame fuel cell 3

[0042] The flame fuel cell 3 comprises a plurality of fuel cell micro-tubes 3-1, each of which is laid in layers around the circumference of the conical inner wall;

[0043] After the fuel cell micro-tubes 3 - 1 are laid in layers around the conical inner wall in the circumferential direction, a conical flame combustion concentration area A is formed in the central area of ​​the conical cavity relative to the central axis.

[0044] Each fuel cell microtube 3-1 is tilted relative to the central axis of the conical cavity; see Figure 2 Each fuel cell microtube 3-1 has a first air inlet 3-1-1 at the bottom, and is connected to the bottom air inlet 1-2 of the torch burner shell 1; the top of the fuel cell microtube 3-1 extends to a position close to the top gas outlet 1-1 of the torch burner shell 1, and is located upstream of the top gas outlet 1-1, and forms a first air nozzle 3-1-2 at the top of the fuel cell microtube 3-1; the inner cavity of the fuel cell microtube 3-1 is an air flow channel 3-1-3; the tube wall of the fuel cell microtube 3-1 has a three-layer structure, the outer layer is the anode 3-1-4; the inner layer is the cathode 3-1-5; the middle layer is the electrolyte 3-1-6.

[0045] In the present invention, the flame fuel cell 3 adopts a micro-tube fuel cell, and the fuel cell micro-tubes 3-1 are stacked in a conical shape along the direction of flame development. The fuel cell micro-tubes 3-1 are arranged above the flame at a certain tilt angle, and appear as a cone in three dimensions. Figure 1 A three-layer flame fuel cell 3 structure is drawn for illustration only. In actual situations, the number of flame fuel cells 3 can be increased according to the associated gas flow rate. More flame fuel cells 3 can be used under large associated gas flow rates to make fuller use of the fuel and increase the power generation capacity of the fuel cell.

[0046] In the conical structure formed by such conical stacking, the bottom flame temperature is high but the heat flux density received by the flame fuel cell 3 is low, while the top flame temperature is low but the heat flux density received by the flame fuel cell 3 is high (fast flow rate and strong heat exchange), thereby solving the problem of uneven temperature in the flow direction.

[0047] The working principle of the flame fuel cell 3 is:

[0048] The rich flame and its combustion products are in direct contact with the outer wall of the fuel cell micro-tube 3-1. Air enters from the bottom of the fuel cell micro-tube 3-1 and flows downstream through the inside of the fuel cell micro-tube, and mixes with the incompletely burned associated gas and combustion exhaust gas at the outlet.

[0049] The structure of the flame fuel cell 3 is as follows: the outer surface of the fuel cell microtube 3-1 is an anode, the inner surface is a cathode, and the middle is an electrolyte layer. The outer diameter of the fuel cell microtube 3-1 is usually about 1 cm, and the length can be customized according to the size of the torch.

[0050] (II) Micro-mix burner 2

[0051] The micro-mix burner 2 includes a micro-tube 2-1, a second air inlet 2-2 and an associated gas fuel inlet 2-3, and is specifically a lean-burn secondary burner.

[0052] Multiple microtubes 2-1 are arranged vertically at intervals; usually hundreds of them; the specific number is not limited; the top jet end of each microtube 2-1 faces the conical flame combustion concentration area A; the bottom of each microtube 2-1 is connected to set the associated gas fuel inlet 2-3; the bottom of the gap between adjacent microtubes 2-1 is connected to set the second air inlet 2-2.

[0053] Using the micro-mix burner 2 as the primary burner of the torch can ensure the stability of the rich flame at a high associated gas flow rate (generally 50-100 m / s), avoid the rich flame from being blown out, and make the flame heat release more uniform in the axial direction.

[0054] (III) Secondary burner 4

[0055] The secondary burner 4 includes a combustion stabilizing blunt body 4-1 and an igniter 4-2; the combustion stabilizing blunt body 4-1 and the igniter 4-2 are arranged in sequence along the gas exhaust flow direction.

[0056] Downstream of the conical top outlet of the flame fuel cell 3, a combustion stabilizing blunt body 4-1 and an igniter 4-2 are arranged to form a secondary burner 4. The incompletely burned associated gas can be quickly mixed with the air blown out from the center of the flame fuel cell 3 tube bundle and burn in the form of a lean flame (excess air), which can ensure that the associated gas is fully burned.

[0057] The present invention also provides a torch combustion method of an oil and gas torch combustion system coupled with a flame fuel cell, comprising the following steps:

[0058] Step S1, primary combustion process of the micro-mixing burner 2:

[0059] The associated gas fuel and air enter the micro-mixing burner 2 through the associated gas fuel inlet 2-3 and the second air inlet 2-2 respectively at a flow rate ratio of excess fuel, and the associated gas fuel is ejected from the micro-tube 2-1, and the air is ejected from the gap between the micro-tubes 2-1; when the air is ejected, the air and the associated gas fuel are well premixed on the surface of the micro-mixing burner 2 by setting the air injection direction, and then a large number of rich small flames are formed on the surface of the micro-mixing burner 2 to convert the associated gas fuel into hydrogen and carbon monoxide;

[0060] In this step, the associated gas fuel and air can enter the micro-mixing burner 2 under the control of a flow meter or a valve, and the equivalence ratio of the associated gas fuel and air is preferably controlled between 1.3 and 1.5, at which time the fuel can efficiently produce hydrogen and carbon monoxide through a rich flame. The equivalence ratio can be changed depending on the associated gas components.

[0061] Step S2, the flame fuel cell 3 performs a process of generating electricity using the associated gas fuel:

[0062] Step S2.1, air flows in from the first air inlet 3-1-1 at the bottom of the fuel cell micro-tube 3-1, and flows downstream in the air flow channel 3-1-3 in the fuel cell micro-tube 3-1;

[0063] Step S2.2: When the air flows in the air channel 3-1-3, part of the oxygen in the air undergoes an electrochemical reduction reaction with the cathode 3-1-5 of the fuel cell microtube 3-1 to generate O 2- ;

[0064] Step S2.3, O 2- Conducted from cathode 3-1-5 to anode 3-1-4 through electrolyte 3-1-6;

[0065] Step S2.4, after the combustion in step S1, the flame tail gas rich in hydrogen and carbon monoxide contacts the surface of the anode 3-1-4 of the fuel cell micro-tube 3-1. Under the high temperature heating of the flame, the hydrogen and carbon monoxide react with the O 2- An electrochemical oxidation reaction occurs, generating electrons;

[0066] Step S2.5, the electrons generated by the anode 3-1-4 are transferred to the cathode 3-1-5 through an external circuit, thereby generating electricity and realizing power generation using associated gas fuel;

[0067] Step S3, the secondary burner 4 performs a secondary combustion process:

[0068] The air ejected from the first air nozzle 3-1-2 at the top of the fuel cell micro-tube 3-1 is quickly mixed with the incompletely burned associated gas and the combustion exhaust gas, and ignited by the igniter 4-2 under the action of the combustion stabilizing blunt body 4-1, and stably burns in the form of a lean flame to ensure that the associated gas is fully burned and avoid the discharge of combustibles and toxic gases into the atmosphere. After the lean secondary combustion, the gas is discharged.

[0069] In this step, by setting up the flame stabilizing blunt body 4-1, a low-speed vortex zone can be formed downstream thereof, and the flame formed by the high-speed reactant flow can be stabilized downstream of the blunt body.

[0070] The present invention proposes an oil and gas torch combustion system and method coupled with a flame fuel cell, which has the following innovative designs:

[0071] (1) The creative combination of flame fuel cells and flare combustion can achieve efficient and clean utilization of associated gas without occupying space on offshore oil and gas platforms or making large investments.

[0072] (2) By stacking the micro-tube flame fuel cells in a conical shape, the problems of short fuel residence time and uneven temperature distribution in existing flame fuel cells are solved, and the power generation capacity can be increased by increasing the number of flame fuel cell layers, thus achieving a modular design.

[0073] (3) By using a micro-mix burner as the primary burner of the torch, the stability of the rich flame under high associated gas flow rate can be ensured, the rich flame can be prevented from being blown out, and the flame heat release can be made more uniform in the axial direction.

[0074] (4) Through the burner structure design, the air flowing out of the center of the microtube flame fuel cell and the incompletely burned associated gas are quickly mixed, and a secondary burner is constructed through a flame-stabilizing blunt body to achieve complete combustion of the associated gas and avoid the emission of combustibles and toxic gases into the atmosphere.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. An oil and gas torch combustion system coupled with a flame fuel cell, characterized in that: It comprises a flare burner housing (1), a micro-mixing burner (2), a flame fuel cell (3) and a secondary burner (4); The upstream side of the bottom of the flare burner housing (1) is connected to the micro-mixing burner (2) and installed; the downstream side of the top gas outlet (1-1) of the flare burner housing (1) is connected to the secondary burner (4) and installed; The interior of the flare burner housing (1) has a cross section that gradually decreases from bottom to top to form a conical cavity; the flame fuel cell (3) is arranged on the conical inner wall of the conical cavity; The flame fuel cell (3) comprises a plurality of fuel cell microtubes (3-1), each of the fuel cell microtubes (3-1) being laid in layers around the circumference of the conical inner wall to form a conical flame combustion concentration area (A) in the central area of ​​the conical cavity relative to the central axis; The micro-mix burner (2) comprises a micro-tube (2-1), a second air inlet (2-2) and an associated gas fuel inlet (2-3); A plurality of microtubes (2-1) are arranged vertically at intervals; the top jet end of each microtube (2-1) faces the conical flame combustion concentration area (A); the bottom of each microtube (2-1) is connected to the associated gas fuel inlet (2-3); and the bottom of the gap between adjacent microtubes (2-1) is connected to the second air inlet (2-2).

2. The oil and gas torch combustion system of a flame fuel cell coupled with an oil and gas torch according to claim 1, characterized in that: Each of the fuel cell microtubes (3-1) is arranged obliquely relative to the central axis of the conical cavity; each of the fuel cell microtubes (3-1) has a first air inlet (3-1-1) at the bottom thereof, which is connected to the bottom air inlet (1-2) of the flare burner housing (1); the top of the fuel cell microtube (3-1) extends to a position of the flare burner housing (1) close to the top gas outlet (1-1), and is located upstream of the top gas outlet (1-1), and a first air nozzle (3-1-2) is formed at the top of the fuel cell microtube (3-1); the inner cavity of the fuel cell microtube (3-1) is an air flow channel (3-1-3); The tube wall of the fuel cell microtube (3-1) has a three-layer structure, wherein the outer layer is the anode (3-1-4); the inner layer is the cathode (3-1-5); and the middle layer is the electrolyte (3-1-6).

3. The oil and gas torch combustion system of a coupled flame fuel cell according to claim 1, characterized in that: The secondary burner (4) comprises a combustion stabilizing blunt body (4-1) and an igniter (4-2); the combustion stabilizing blunt body (4-1) and the igniter (4-2) are arranged in sequence along the gas exhaust flow direction.

4. A torch combustion method of an oil and gas torch combustion system of a coupled flame fuel cell according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1, primary combustion process of the micro-mixing burner (2): The associated gas fuel and air enter the micro-mixing burner (2) through the associated gas fuel inlet (2-3) and the second air inlet (2-2) respectively at a flow rate ratio of excess fuel, the associated gas fuel is ejected from the micro-tube (2-1), and the air is ejected from the gaps between the micro-tubes (2-1); the air and the associated gas fuel are premixed on the surface of the micro-mixing burner (2) by setting the air injection direction, thereby forming a large number of rich small flames on the surface of the micro-mixing burner (2), and converting the associated gas fuel into hydrogen and carbon monoxide; Step S2, the flame fuel cell (3) performs a process of generating electricity by utilizing the associated gas fuel: Step S2.1, air flows in from the first air inlet (3-1-1) at the bottom of the fuel cell micro-tube (3-1), and flows downstream in the air flow channel (3-1-3) in the fuel cell micro-tube (3-1); Step S2.2, when the air flows in the air channel (3-1-3), part of the oxygen in the air undergoes an electrochemical reduction reaction with the cathode (3-1-5) of the fuel cell microtube (3-1) to generate O 2- ; Step S2.3, O 2- Conducted from cathode (3-1-5) to anode (3-1-4) through electrolyte (3-1-6); Step S2.4, after the combustion in step S1, the flame-rich tail gas rich in hydrogen and carbon monoxide contacts the surface of the anode (3-1-4) of the fuel cell microtube (3-1), and under the high temperature heating of the flame, the hydrogen and carbon monoxide react with the O2 transferred to the anode (3-1-4). 2- An electrochemical oxidation reaction occurs, generating electrons; Step S2.5, the electrons generated by the anode (3-1-4) are transferred to the cathode (3-1-5) through an external circuit, thereby generating electricity and realizing power generation using associated gas fuel; Step S3, the secondary burner (4) performs a secondary combustion process: The air ejected from the first air nozzle (3-1-2) at the top of the fuel cell microtube (3-1) is quickly mixed with the incompletely burned associated gas and the combustion exhaust gas, and is ignited by the igniter (4-2) under the action of the combustion stabilizing blunt body (4-1), and stably burns in the form of a lean flame to ensure that the associated gas is fully burned; after the lean secondary combustion, the gas is discharged.

5. The torch combustion method of the oil and gas torch combustion system coupled with a flame fuel cell according to claim 4, characterized in that: In step S1, the equivalence ratio of the associated gas fuel to air is between 1.3 and 1.5.

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