A built-in diffusion combustion device and method for a fire tube type oil field heating furnace

Abstract

A built-in diffusion combustion device and method for a fire tube type oil field heating furnace belongs to the technical field of fire tube type oil field heating furnace. The device and method include two fuel staging and three air staging. In the combustion stage of the fire tube, the primary fuel and the primary air burn in the primary combustion chamber. The secondary combustion transports the fuel to the depth of the fire tube through the diffusion tube, and after mixing with the secondary air and the tertiary air that complement each other, it slowly diffuses and burns in the direction away from the wall of the fire tube. The present invention lengthens the fuel combustion flame and reduces the combustion intensity, which can effectively reduce the concentrated thermal stress caused by the local high temperature of the fire tube and avoid the problem of equipment burning caused by high temperature. The process structure is simple and the diffusion combustion device is easy to replace and maintain. Compared with the traditional fire tube type oil field heating furnace combustion device, it reduces the combustion consumption and operating costs, and ensures the efficient and long-term operation of the fire tube type oil field heating furnace.

Description

Technical Field

[0001] The invention relates to the technical field of fire tube type oil field heating furnaces, and in particular to a built-in diffusion combustion device and method for fire tube type oil field heating furnaces. Background Art

[0002] As an important heating equipment in the oil refining industry, the widely distributed oil field heating furnace provides a reliable heat source and power for the crude oil gathering and transportation system. As a typical furnace type, the fire tube heating furnace has been widely used in various oil fields in my country. Its principle is to transfer the heat generated by the combustion of fuel directly to the production medium in the pressure vessel through the fire tube wall, and the heated production medium absorbs the heat by flooding the smoke tube and the fire tube.

[0003] However, in actual production operation, as the fire tube type heating furnace runs for a long time, the local high temperature generated by combustion causes impurities to scale and deposit on the wall of the fire tube, affecting the heat exchange effect between the fire tube and the medium. In order to ensure the temperature requirements of the system, the combustion power must be increased, which will lead to higher working temperatures of the fire tube, further accelerating the scaling speed of the fire tube, forming a vicious circle, and easily causing the fire tube to bulge, deform, perforate or burn due to thermal stress. In addition, excessive heat load of the heating furnace will also lead to increased exhaust temperature, reduced thermal efficiency, increased energy consumption and increased operating costs. The fire tube type oilfield heating furnace contains flammable and explosive media such as oil and associated gas. Excessive combustion intensity can easily lead to equipment burning, posing a huge safety hazard, which seriously affects the smooth operation of oilfield production. Summary of the invention

[0004] Technical problem to be solved: In order to solve the problems of bulging, deformation, perforation or burning of the fire tube equipment caused by local high temperature of combustion in the above-mentioned fire tube type oil field heating furnace, and high flue gas outlet temperature, low thermal efficiency and increased fuel consumption caused by excessive heat load, the present invention provides a built-in diffuse combustion device and method for a fire tube type oil field heating furnace. The device and method can elongate the fuel combustion flame and reduce the combustion intensity, which can effectively reduce the concentrated thermal stress caused by local high temperature of the fire tube, avoid equipment burning caused by high temperature, reduce combustion consumption and operating costs, thereby ensuring efficient and long-term operation of the fire tube type oil field heating furnace.

[0005] Technical solution: A built-in diffusion combustion method for a fire tube type oil field heating furnace, including a two-fuel staging method and a three-air staging method, wherein the two-fuel staging method is specifically as follows: the combustion stage in the fire tube is divided into a primary combustion zone and a diffusion combustion zone, the primary fuel accounting for 15% to 30% of the volume is burned in the primary combustion cavity through a primary fuel pipe, and the secondary fuel accounting for 70% to 85% of the volume is transported to the main diffusion combustion chamber inside the fire tube through a secondary fuel diffusion pipe for diffusion combustion;

[0006] The three-stage air classification method is specifically as follows: the primary air enters the primary combustion chamber through the primary air pipe to mix with the primary fuel for combustion, the secondary air enters the diffuse combustion zone from the secondary air pipe to realize diffuse primary combustion, and the tertiary air enters the main diffuse combustion chamber through the tertiary air pipe to supplement the air required for diffuse combustion;

[0007] The primary fuel pipe is a tapered outlet, and the primary fuel flows into the primary combustion chamber from the primary fuel pipe outlet and the primary fuel dispersion hole respectively;

[0008] The secondary fuel diffusion tube is provided with a row of secondary fuel diffusion holes at equal distances, and two secondary fuel diffusion tubes are placed close to the fire tube, with one side of the secondary fuel diffusion hole facing away from the wall of the fire tube;

[0009] The primary air pipe surrounds the primary fuel pipe and enters the primary combustion chamber from six air pipes respectively. The secondary air pipe and the tertiary air pipe each have two staggered and symmetrical input pipes. The secondary air pipe is used to increase air for primary diffusion combustion, and the tertiary air pipe is used to supplement air for main diffusion combustion.

[0010] A built-in diffuse combustion device for a fire tube type oil field heating furnace based on the above method comprises a shell, a fire tube, a chimney, a medium input pipe, a head, a tube bundle and a medium outlet, the lower part of the open end of the head is connected to the fire tube, the upper part is connected to one end of the tube bundle, the other end of the tube bundle is connected to the chimney, the tube bundle and the fire tube are tightly connected, the fire tube, the tube bundle and the head are arranged on one side of the shell, and do not contact the upper and lower ends of the shell, the medium input pipe is placed horizontally, one end extends into the shell from the bottom, and the other end passes through the shell, medium input holes are distributed on the medium input pipe, and the medium outlet is arranged on the top of the shell near the chimney, the fire tube comprises a fire tube wall and a primary combustion zone and a diffuse combustion zone arranged inside the fire tube wall and connected to each other, the fire tube wall is a cylindrical cavity with an open end and a closed end, the open end of the fire tube wall is connected to the head, the fire tube wall comprises a plurality of groups of annular fins, and the plurality of groups of annular fins are arranged on the outer side of the fire tube wall for transferring heat;

[0011] The primary combustion zone includes a primary fuel pipe, six primary air pipes and a primary combustion cavity. The primary combustion cavity is a cylindrical cavity with an open end and a closed end. The primary combustion cavity is arranged inside the fire tube along the central axis and shares an outer wall with the closed end of the fire tube wall. The outlet end of the primary fuel pipe is connected to the primary combustion cavity. The outlet ends of the six primary air pipes are connected to the primary combustion cavity, and the six primary air pipes are evenly distributed on the outside of the primary fuel pipe.

[0012] The diffuse combustion zone includes two secondary air pipes, two tertiary air pipes, two secondary fuel diffusion pipes, secondary fuel diffusion holes and a main diffuse combustion chamber. The main diffuse combustion chamber is the remaining part of the fire tube wall except the primary combustion chamber. The two secondary fuel diffusion pipes are evenly distributed inside the fire tube and close to the fire tube wall. The secondary fuel diffusion pipes are provided with secondary fuel diffusion holes. The secondary fuel diffusion holes are arranged on the side of the secondary fuel diffusion pipe facing away from the fire tube wall. The two secondary air pipes are symmetrically distributed along the center on the outside of the primary combustion chamber. The two tertiary air pipes are symmetrically distributed along the center on the outside of the primary combustion chamber and are staggered with the two secondary air pipes. The outlet end of the tertiary air pipe is longer than the secondary air pipe.

[0013] Preferably, the secondary air pipe is half the length of the tertiary air pipe.

[0014] The present invention delivers the primary fuel accounting for 15-30% of the volume into the primary combustion cavity through the primary fuel pipe, and the primary air enters the primary combustion cavity through the primary air pipe and mixes with the primary fuel for primary combustion; the secondary fuel accounting for 70-85% of the volume is delivered to the main diffuse combustion chamber through the secondary fuel diffusion pipe, and the secondary air enters the diffuse combustion zone through the secondary air pipe and mixes with the secondary fuel to achieve diffuse primary combustion, and the tertiary air enters the main diffuse combustion chamber through the tertiary air pipe to supplement the air required for diffuse combustion. The high-temperature flue gas generated by the combustion in the fire tube transfers heat to the medium through the wall of the fire tube, and then enters the tube bundle through the head to exchange heat with the medium again, and finally the flue gas is discharged from the chimney. Compared with the direct combustion method of the traditional fire tube type oil field heating furnace, the combustion flame is elongated, the combustion intensity is reduced, and the local high temperature near the burner is effectively reduced. The air required for fuel combustion is input in multiple stages, which can reduce the intensity of combustion, so that the fuel burns slowly and evenly in the entire fire tube, effectively increasing the heat transfer efficiency between the wall of the fire tube and the medium, and reducing excessive fuel consumption.

[0015] The built-in diffusion combustion device for the fire tube type oil field heating furnace described in the present invention is divided into five processes, namely, primary combustion, diffusion combustion, fire tube heating, tube bundle heating and flue gas emission, including a primary fuel pipe, a primary air pipe, a primary fuel dispersion hole, a primary combustion cavity, a secondary air pipe, a tertiary air pipe, a secondary fuel diffusion pipe, a secondary fuel diffusion hole, a main diffusion combustion cavity, a head, a tube bundle, annular fins and a chimney. The primary fuel and the primary air realize primary combustion in the primary combustion cavity to release heat, the secondary fuel diffuses into the main diffusion combustion cavity through the secondary fuel diffusion hole, and is mixed with the air from the secondary air pipe and the tertiary air pipe to realize diffusion combustion. The high-temperature flue gas generated by the combustion in the fire tube transfers heat to the medium through the fire tube wall or the annular fins, and then enters the tube bundle through the head to exchange heat with the medium again, and finally the flue gas is discharged from the chimney.

[0016] Beneficial effects: The built-in diffusion combustion method and device of the fire tube type oil field heating furnace of the present invention can be used to provide a reliable heat source and power for the crude oil gathering and transportation system. The method combines two fuel classifications and three air classifications, has a simple process structure, is easy to replace and maintain the diffusion combustion device, can lengthen the fuel combustion flame, reduce the combustion intensity, and can effectively reduce the concentrated thermal stress caused by the local high temperature of the fire tube, avoid the problem of equipment burning caused by high temperature, reduce combustion consumption and operating costs, thereby ensuring the efficient and long-term operation of the fire tube type oil field heating furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a fire tube type oil field heating furnace with a built-in diffuse combustion method;

[0018] Figure 2 It is a schematic diagram of the structure with two fuel stages and three air stages.

[0019] In the figure, (1) primary fuel pipe; (2) primary air pipe; (3) primary fuel dispersion hole; (4) primary combustion chamber; (5) secondary air pipe; (5-a) and (5-b) secondary air inlets; (6) tertiary air pipe; (6-a) and (6-b) tertiary air inlets; (7) secondary fuel diffusion pipe; (8) secondary fuel dispersion hole; (9) medium input hole; (10) main diffusion combustion chamber; (11) medium input pipe; (12) end cap; (13) tube bundle; (14) annular fin; (15) medium outlet; (16) chimney. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0021] The fuel in the embodiments of this specification is natural gas.

[0022] Example 1

[0023] A built-in diffusion combustion method for a fire tube type oil field heating furnace includes a two-fuel staging method and a three-air staging method, wherein the two-fuel staging method is specifically as follows: the combustion stage in the fire tube is divided into a primary combustion zone and a diffusion combustion zone, a primary fuel accounting for 15% to 30% of the volume is burned in a primary combustion cavity 4 through a primary fuel pipe 1, and a secondary fuel accounting for 70% to 85% of the volume is transported to a main diffusion combustion chamber 10 inside the fire tube through a secondary fuel diffusion pipe 7 for diffusion combustion.

[0024] The three-stage air classification method is specifically as follows: primary air enters the primary combustion chamber 4 through the primary air pipe 2 and is mixed with the primary fuel for combustion; secondary air enters the diffuse combustion zone from the secondary air pipe 5 to realize diffuse primary combustion; and tertiary air enters the main diffuse combustion chamber 10 through the tertiary air pipe 6 to supplement the air required for diffuse combustion.

[0025] The primary fuel pipe 1 is a tapered outlet, and the primary fuel flows into the primary combustion chamber 4 from the outlet of the primary fuel pipe 1 and the primary fuel dispersion hole 3 respectively.

[0026] The secondary fuel diffusion tube 7 is provided with a row of secondary fuel diffusion holes 8 at equal distances, and two secondary fuel diffusion tubes 7 are placed close to the fire tube, with one side of the secondary fuel diffusion hole 8 facing away from the wall of the fire tube.

[0027] The primary air pipe 2 surrounds the primary fuel pipe 1 and enters the primary combustion chamber 4 from six air pipes respectively. The secondary air pipe 5 and the tertiary air pipe 6 each have two staggered and symmetrical input pipes. The secondary air pipe 5 is used to increase the air for primary diffuse combustion, and the tertiary air pipe 6 is used to supplement the air for main diffuse combustion.

[0028] Based on the above method, the built-in diffusion combustion device used in the fire tube type oil field heating furnace is shown in Figure 1 and Figure 2 , including a shell, a fire tube, a chimney 16, a medium input pipe 11, a head 12, a tube bundle 13 and a medium outlet 15, the lower part of the open end of the head 12 is connected to the fire tube, and the upper part is connected to one end of the tube bundle 13, the other end of the tube bundle 13 is connected to the chimney 16, the tube bundle 13 and the fire tube are tightly connected, the fire tube, the tube bundle 13 and the head 12 are arranged on one side of the shell, and are not in contact with the upper and lower ends of the shell, the medium input pipe 11 is placed horizontally, one end extends into the shell from the bottom, and the other end passes through the shell, medium input holes 9 are distributed on the medium input pipe 11, and the medium outlet 15 is arranged on the top of the shell near the chimney, the fire tube includes a fire tube wall and a primary combustion zone and a diffuse combustion zone arranged inside the fire tube wall and connected to each other, the fire tube wall is a cylindrical cavity with an open end and a closed end, the open end of the fire tube wall is connected to the head 12, the fire tube wall includes a plurality of groups of annular fins 14, and the plurality of groups of annular fins 14 are arranged on the outer side of the fire tube wall for transferring heat;

[0029] The primary combustion zone includes a primary fuel pipe 1, six primary air pipes 2 and a primary combustion cavity 4. The primary combustion cavity 4 is a cylindrical cavity with an open end and a closed end. The primary combustion cavity 4 is arranged inside the fire tube along the central axis and shares an outer wall with the closed end of the fire tube wall. The outlet end of the primary fuel pipe 1 is connected to the primary combustion cavity 4, and the outlet ends of the six primary air pipes 2 are connected to the primary combustion cavity 4, and the six primary air pipes 2 are evenly distributed on the outside of the primary fuel pipe 1.

[0030] The diffuse combustion zone includes two secondary air pipes 5, two tertiary air pipes 6, two secondary fuel diffusion pipes 7, secondary fuel diffusion holes 8 and a main diffuse combustion chamber 10. The main diffuse combustion chamber 10 is the remaining part of the fire tube wall except the primary combustion chamber 4. The two secondary fuel diffusion pipes 7 are evenly distributed inside the fire tube and close to the fire tube wall. The secondary fuel diffusion pipes 7 are provided with secondary fuel diffusion holes 8. The secondary fuel diffusion holes 8 are arranged on the side of the secondary fuel diffusion pipe 7 facing away from the fire tube wall. The two secondary air pipes 5 are symmetrically distributed along the center on the outside of the primary combustion chamber 4. The two tertiary air pipes 6 are symmetrically distributed along the center on the outside of the primary combustion chamber 4 and are staggered with the two secondary air pipes 5 (see for details). Figure 2 The distribution of the secondary air pipe 5 is shown as the secondary air inlet 5-a and 5-b, and the distribution of the tertiary air pipe 6 is shown as the tertiary air inlet 6-a and 6-b). The outlet end of the tertiary air pipe 6 is longer than the secondary air pipe 5.

[0031] The secondary fuel diffusion tube has a row of secondary fuel diffusion holes at equal distances, and two secondary fuel diffusion tubes are placed close to the fire tube, with one side of the secondary fuel diffusion holes facing away from the fire tube wall; the burning flame is away from the fire tube wall, which can effectively avoid the generation of concentrated thermal stress and prevent the fire tube from burning.

[0032] The primary fuel, which accounts for 15-30% of the volume, is delivered to the primary combustion chamber 4 through the primary fuel pipe 1, and the primary air enters the primary combustion chamber 4 through the primary air pipe 2 and mixes with the primary fuel for primary combustion; the secondary fuel, which accounts for 70-85% of the volume, is delivered to the main diffuse combustion chamber 10 through the secondary fuel diffusion pipe 7, and the secondary air enters the diffuse combustion zone through the secondary air pipe 5 and mixes with the secondary fuel to realize diffuse primary combustion. The tertiary air enters the main diffuse combustion chamber 10 through the tertiary air pipe 6 to supplement the air required for diffuse combustion. The high-temperature flue gas generated by the combustion in the fire tube transfers heat to the medium through the fire tube wall, and then enters the tube bundle 13 through the head 12 to exchange heat with the medium again, and finally the flue gas is discharged from the chimney 16.

[0033] Example 2

[0034] The same as the first embodiment, except that the secondary air pipe 5 is half the length of the tertiary air pipe 6 .

[0035] The present invention causes the fuel combustion flame to be elongated and the combustion intensity to be reduced after primary combustion and diffuse combustion in the fire tube type combustion chamber, which can effectively reduce the concentrated thermal stress caused by the local high temperature of the fire tube, thereby avoiding equipment burning due to excessive combustion intensity, thereby ensuring the safe and stable operation of the fire tube type oil field heating furnace.

[0036] The above is 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 principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A built-in diffusion combustion method for a fire tube type oil field heating furnace, characterized in that: Based on a built-in diffuse combustion device for a fire tube type oil field heating furnace, the fire tube type oil field heating furnace with the built-in diffuse combustion device is divided into five processes: primary combustion, diffuse combustion, fire tube heating, tube bundle heating and flue gas emission, and includes a shell, a fire tube, a chimney (16), a medium input pipe (11), a head (12), a tube bundle (13) and a medium outlet (15), wherein the lower part of the open end of the head (12) is connected to the fire tube, and the upper part is connected to one end of the tube bundle (13), and the other end of the tube bundle (13) is connected to the chimney (16), the tube bundle (13) and the fire tube are tightly connected, and the fire tube, the tube bundle (13) and the head (12) are arranged on one side of the shell. , and does not contact the upper and lower ends of the shell, the medium input pipe (11) is placed horizontally, one end of which extends into the shell from the bottom and the other end passes through the shell, the medium input holes (9) are distributed on the medium input pipe (11), and the medium outlet (15) is arranged on the side of the top of the shell near the chimney, characterized in that the fire tube includes a fire tube wall and a primary combustion zone and a diffuse combustion zone arranged inside the fire tube wall and connected to each other, the fire tube wall is a cylindrical cavity with an opening at one end and a closed end at the other end, the open end of the fire tube wall is connected to the head (12), the fire tube wall includes a plurality of groups of annular fins (14), and the plurality of groups of annular fins (14) are arranged on the outside of the fire tube wall for transferring heat; The primary combustion zone comprises a primary fuel pipe (1), six primary air pipes (2) and a primary combustion cavity (4); the primary combustion cavity (4) is a cylindrical cavity with an open end and a closed end; the primary combustion cavity (4) is arranged inside the fire tube along the central axis and shares an outer wall with the closed end of the fire tube wall; the outlet end of the primary fuel pipe (1) is connected to the primary combustion cavity (4); the outlet ends of the six primary air pipes (2) are connected to the primary combustion cavity (4); and the six primary air pipes (2) are evenly distributed on the outside of the primary fuel pipe (1); The diffuse combustion zone comprises two secondary air pipes (5), two tertiary air pipes (6), two secondary fuel diffusion pipes (7), secondary fuel diffusion holes (8) and a main diffuse combustion chamber (10). The main diffuse combustion chamber (10) is the remaining part of the interior of the fire tube wall except the primary combustion chamber (4). The two secondary fuel diffusion pipes (7) are evenly distributed inside the fire tube and close to the fire tube wall. The secondary fuel diffusion pipes (7) are provided with secondary fuel diffusion holes (8). The secondary fuel diffusion holes (8) are arranged on the side of the secondary fuel diffusion pipe (7) facing away from the fire tube wall. The two secondary air pipes (5) are symmetrically distributed along the center outside the primary combustion chamber (4). The two tertiary air pipes (6) are symmetrically distributed along the center outside the primary combustion chamber (4) and are staggered with the two secondary air pipes (5). The outlet end of the tertiary air pipe (6) is longer than the secondary air pipe (5). The internal diffusion combustion method for a fire tube type oil field heating furnace comprises a two-stage fuel staging method and a three-stage air staging method, wherein the two-stage fuel staging method is specifically as follows: the combustion stage in the fire tube is divided into a primary combustion zone and a diffusion combustion zone, the primary fuel accounting for 15% to 30% by volume is transmitted through a primary fuel pipe (1) to perform primary combustion in a primary combustion cavity (4), and the secondary fuel accounting for 70% to 85% by volume is transported to a main diffusion combustion chamber (10) inside the fire tube through a secondary fuel diffusion pipe (7) to perform diffusion combustion; The three-stage air classification method is specifically as follows: primary air enters the primary combustion chamber (4) through the primary air pipe (2) to mix with the primary fuel and burn, secondary air enters the diffuse combustion zone from the secondary air pipe (5) to realize diffuse primary combustion, and tertiary air enters the main diffuse combustion chamber (10) through the tertiary air pipe (6) to supplement the air required for diffuse combustion; The primary fuel pipe (1) is a tapered outlet, and the primary fuel flows into the primary combustion chamber (4) from the outlet of the primary fuel pipe (1) and the primary fuel dispersion hole (3) respectively; The secondary fuel diffusion tube (7) is provided with a row of secondary fuel diffusion holes (8) at equal distances, two secondary fuel diffusion tubes (7) are arranged close to the fire tube, and one side of the secondary fuel diffusion hole (8) faces away from the wall of the fire tube; The primary air pipe (2) surrounds the primary fuel pipe (1) and enters the primary combustion chamber (4) from six air pipes respectively. The secondary air pipe (5) and the tertiary air pipe (6) each have two staggered and symmetrical input pipes. The secondary air pipe (5) increases air for primary diffuse combustion, and the tertiary air pipe (6) supplements air for main diffuse combustion.

2. The internal diffusion combustion method for a fire tube type oil field heating furnace according to claim 1 is characterized in that: The secondary air pipe (5) is half the length of the tertiary air pipe (6).

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