Coal-fired circulating fluidized bed oil field steam injection furnace

Abstract

The invention relates to the technical field of boilers, and provides a coal-fired circulating fluidized bed oil field steam injection furnace which comprises a steel frame, a coil pipe hearth is installed on the steel frame, and a coil pipe water cooling air chamber and a steam-water separation device with a built-in separator are arranged at the bottom and the top of the coil pipe hearth respectively. An air distribution plate is arranged at the joint of the coil pipe water-cooling air chamber and the coil pipe hearth, a rear wall flange of the coil pipe water-cooling air chamber is connected with an ignition burner, and a coal feeding device communicated with the coil pipe hearth is arranged on the side wall of the coil pipe hearth; the cyclone separator is a high-temperature heat-insulation cyclone separator, a high-strength wear-resistant refractory material is laid on the inner wall of the cyclone separator to prevent erosive wear, and meanwhile, the outlet of the coil pipe hearth and the inlet of the cyclone separator are connected through the non-metal expansion joint, so that the sealing performance is ensured, and the separation efficiency is improved; the economizer adopts H-shaped fin countercurrent arrangement, so that the heat exchange efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of boiler, in particular to a coal-fired circulating fluidized bed oilfield steam injection furnace. BACKGROUND

[0002] Most of the crude oil produced in Xinjiang Karamay oilfield belongs to heavy oil, which has large viscosity and poor flowability, and is difficult to develop. At present, the main solution is to inject high-temperature and high-pressure steam into the underground of the oilfield to reduce the viscosity of the crude oil and increase the flowability of the crude oil, so as to facilitate the exploitation and transportation of the crude oil. At present, the oilfield steam injection boiler mainly uses oil or natural gas as energy, and the operation cost is large, and the ton steam cost is about 178.4 yuan / ton. While China is rich in coal resources, if coal is used as fuel, the ton steam cost is only about 101.3 yuan / ton, but the current technical application route has not been effectively solved.

[0003] At present, the key components of the cyclone separator and the coil furnace chamber are long-term operated in a high-temperature environment, which is easy to be affected by erosion and wear, resulting in shortening of the service life of the equipment. The superheater, coal economizer and air preheater in the flue are arranged unreasonably, which may cause poor flue gas flow and affect the heat exchange efficiency.

[0004] The unreasonable design of the steam-water separation device causes the steam to contain a large amount of water, which affects the steam injection quality. The structure of the air distribution plate and the return feeder is complex, which increases the maintenance difficulty and cost of the equipment. The unreasonable design of the combustion device causes the fuel to be insufficiently combusted, which affects the overall performance of the boiler.

[0005] Based on the above problems, a coal-fired circulating fluidized bed oilfield steam injection furnace is provided. SUMMARY

[0006] In view of the shortcomings of the prior art, the present application provides a coal-fired circulating fluidized bed oilfield steam injection furnace, which overcomes the shortcomings of the prior art, and effectively solves the problems of high fuel cost, short wear-resistant life, high maintenance cost and many non-stop times of the coal-fired circulating fluidized bed oilfield steam injection furnace in actual application through the spiral winding water cooling wall, the built-in steam-water separator, the welding pin + gradient wear-resistant castable technology, the vertical type structure and the integrated air distribution plate.

[0007] To achieve the above purpose, the present application is realized by the following technical scheme:

[0008] A coal-fired circulating fluidized bed oilfield steam injection furnace, comprising a steel frame, wherein the steel frame is provided with a coil furnace chamber, and the bottom and top of the coil furnace chamber are respectively provided with a coil water cooling air chamber and a steam-water separation device with a built-in separator; an air distribution plate is arranged at the connection between the coil water cooling air chamber and the coil furnace chamber, a point ignition burner is connected to the rear wall flange of the coil water cooling air chamber, and the side wall of the coil furnace chamber is provided with a coal feeding device communicated therewith.

[0009] The side wall of the coil furnace is communicated with a cyclone separator near the steam-water separation device, the bottom of the cyclone separator is provided with a return feeder communicated with the coil furnace, the top of the cyclone separator is communicated with a flue, the flue is sequentially provided with an evaporation convection tube bundle, a superheater, a coal economizer and an air preheater according to the flow direction of the flue gas, and an external energy-saving heat exchanger is connected between the coal economizer and the air preheater.

[0010] Preferably, the cyclone separator is a high-temperature adiabatic cyclone separator, the inner wall of the cyclone separator adopts a structure of nails and brick supports, and is coated with wear-resistant refractory material, the cyclone separator is arranged at the outlet of the coil furnace, the smoke temperature at the inlet of the cyclone separator is 850-950℃, a non-metallic expansion joint is arranged at the outlet of the coil furnace and the inlet of the cyclone separator, and the separated solid particles are sent back to the furnace through the return feeder; the separated flue gas enters the flue and heats the tail heating surface.

[0011] Preferably, the flue is installed on a steel frame, the evaporation convection tube bundle includes an upper evaporation convection tube bundle and a lower evaporation convection tube bundle; the evaporation convection tube bundle adopts a H-shaped fin or a light tube countercurrent arrangement, the evaporation convection tube bundle is fixed on the flue guard plate through a support cross beam, the support cross beam is a hollow structure welded by steel plates, cooling air from the outlet of the secondary air fan is introduced into the inside, an adjusting valve is arranged on the cooling air inlet pipeline of the support cross beam, and the outlet is connected to the negative pressure area of the flue before the dust collector.

[0012] Preferably, the flue is installed on a steel frame, the superheater includes a high-temperature superheater and a low-temperature superheater; the superheater in the flue is arranged below the evaporation convection tube bundle, the superheater adopts a light tube countercurrent arrangement, the tube bundle of the superheater is fixed on the flue guard plate through a support cross beam, the support cross beam is a hollow structure welded by steel plates, cooling air from the outlet of the secondary air fan is introduced into the inside, an adjusting valve is arranged on the cooling air inlet pipeline of the support cross beam, and the outlet is connected to the negative pressure area of the flue before the dust collector.

[0013] Preferably, the coal economizer includes a high-temperature coal economizer and a low-temperature coal economizer; the high-temperature coal economizer and the low-temperature coal economizer in the flue are arranged below the superheater, the coal economizer adopts an H-shaped fin countercurrent arrangement, an expansion sealing structure is arranged at the wall-penetrating tube bundle of the coal economizer, the tube bundle of the coal economizer is fixed on the flue guard plate through a support cross beam, the support cross beam is a hollow structure welded by steel plates, cooling air from the outlet of the secondary air fan is introduced into the inside, an adjusting valve is arranged on the cooling air inlet pipeline of the support cross beam, and the outlet is connected to the negative pressure area of the flue before the dust collector.

[0014] Preferably, the air preheater comprises a secondary air preheater and a primary air preheater; the air outlet of the secondary air preheater is connected to the secondary air injection port in the middle of the coil furnace; the air outlet of the primary air preheater is connected to the primary air inlet of the coil water-cooled air chamber, and the air preheater is provided with a enamel surface treatment.

[0015] Preferably, the ignition burner, the coal feeder, the coil furnace, the coil water-cooled air chamber and the return feeder constitute a combustion section; the evaporation convection tube bundle, the superheater, the economizer, the preheater and the energy-saving external energy-saving heat exchanger constitute a heat exchange section; the coal feeder comprises at least two coal feeding pipes, each of which is provided with a coal feeding air pipe and a coal spreading air pipe, and each of the air pipe and the coal spreading air pipe is provided with an air door.

[0016] Preferably, the return feeder is communicated with the coil furnace through a return pipe; the fly ash separated from the return feeder is sent back to the coil furnace for continuous combustion, the return pipe is provided with an air door and a flow meter for adjusting the air volume; the center line of the return port of the return feeder is higher than the plane of the air distribution plate by 1300 mm, and the return pipe is provided with a metal expansion joint.

[0017] Preferably, the coil furnace adopts a spiral winding type water-cooled wall pipe; a welding fin and a welding pin structure are arranged on the inner wall of the spiral winding type water-cooled wall pipe, and wear-resistant castable is laid; the spiral winding type water-cooled wall pipe is formed by winding a plurality of pipes; the pitch between adjacent pipes is 80 mm.

[0018] Preferably, the air distribution plate is horizontally arranged at the bottom of the coil furnace; a plurality of bell-shaped air caps arranged in a matrix are welded on the upper part of the air distribution plate, and the joint between the air cap and the air distribution plate is filled with high-strength wear-resistant castable and medium-quality thermal insulation castable which are layered and casted.

[0019] The air distribution plate is integrated with two vertical slag discharge pipes which are connected to a continuous operation slag discharge pipe, an accident slag discharge pipe, a direct discharge slag channel and a quick-opening gate valve; the side of the coil water-cooled air chamber is further provided with an inspection door; the steam injection furnace is a vertical structure and adopts a flue burner bed ignition.

[0020] The present application provides a coal-fired circulating fluidized bed steam injection furnace for oil fields. The cyclone separator adopts a high-temperature adiabatic cyclone separator, and high-strength wear-resistant refractory material is laid on the inner wall to prevent erosion and wear; at the same time, a non-metallic expansion joint is used to connect the outlet of the coil furnace and the inlet of the cyclone separator to ensure the sealing performance and improve the separation efficiency.

[0021] The economizer adopts H-shaped fin reverse flow arrangement to improve the heat exchange efficiency. The tube bundle of the economizer is fixed on the flue guard plate through a support beam which is a hollow structure welded by heat-resistant steel plates and through which cooling air is introduced to control the flow rate and prevent wear;

[0022] The air preheater is treated with enamel surface to improve the wear resistance, and the secondary air preheater and the primary air preheater are connected to the middle part of the coil furnace and the primary air inlet of the coil water-cooled air chamber respectively to provide fluidized air for the air distribution plate;

[0023] The steam-water separation device is a high-efficiency steam-water separation device, which realizes high-efficiency separation of steam and water and improves the steam dryness.

[0024] The ignition burner, the coal feeding device, the coil furnace, the coil water-cooled air chamber and the material return device constitute a combustion section to ensure sufficient combustion of the fuel. The material return device is communicated with the coil furnace through a material return pipe, and the fly ash separated from the material return device is sent back to the coil furnace for continuous combustion to improve the combustion efficiency.

[0025] The bell-shaped air cap arranged in a matrix is welded to the upper part of the air distribution plate, and the joint part of the air cap and the air distribution plate is filled with high-strength wear-resistant castable and medium thermal insulation castable poured in layers to ensure uniform air distribution.

[0026] The coil furnace adopts a spiral winding water-cooled wall pipe, and high-strength wear-resistant refractory material is laid on the inner wall to prevent wear and tear. The flue is installed on a steel frame, and the evaporation convection tube bundle, the superheater, the coal economizer, the air preheater and the external energy-saving heat exchanger constitute a heat exchange section to ensure smooth flow of flue gas and improve the heat exchange efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The figure is a structural schematic diagram of the present application.

[0028] Figure 2 The figure is a coal particle distribution diagram of the present application.

[0029] The figure is a coal particle distribution diagram of the present application. DETAILED DESCRIPTION

[0030] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0031] Referring to the drawings Figures 1-2 As shown in the drawings, a coal-fired circulating fluidized bed oilfield steam injection furnace comprises a steel frame 18, a coil furnace chamber 4 is mounted on the steel frame 18, a coil water-cooled air chamber 3 and a steam-water separation device 5 with an internal separator are arranged at the bottom and the top of the coil furnace chamber 4 respectively; a wind distribution plate 21 is arranged at the connection between the coil water-cooled air chamber 3 and the coil furnace chamber 4, a point ignition burner 1 is flange-connected to the back wall of the coil water-cooled air chamber 3, and a coal feeding device 2 is arranged in the side wall of the coil furnace chamber 4 and communicates with the coil furnace chamber 4.

[0032] A cyclone separator 8 is communicated with the side wall of the coil furnace chamber 4 and is close to the steam-water separation device 5, a return feeder 7 that communicates with the coil furnace chamber 4 is arranged at the bottom of the cyclone separator 8, and the top of the cyclone separator 8 communicates with a flue, the flue is sequentially provided with an evaporation convection tube bundle, a superheater, an economizer and an air preheater according to the smoke flow direction, and an external energy-saving heat exchanger 17 is connected between the economizer and the preheater.

[0033] The cyclone separator 8 is a high-temperature adiabatic cyclone separator 8, the inner wall of the cyclone separator 8 is provided with a structure of a nail and a brick frame, and is coated with wear-resistant and refractory materials to prevent erosion and wear, the cyclone separator 8 is arranged at the outlet of the coil furnace chamber 4, the smoke temperature at the inlet of the cyclone separator 8 is 850-950℃, a non-metallic expansion joint 6 is arranged at the outlet of the coil furnace chamber 4 and the inlet of the cyclone separator 8 to ensure the sealing performance of the connection, and the separated solid particles are sent back to the furnace chamber through the return feeder 7; the separated smoke enters the flue and heats the tail heating surface.

[0034] The flue is mounted on the steel frame 18, the evaporation convection tube bundle comprises an upper evaporation convection tube bundle 9 and a lower evaporation convection tube bundle 10, the evaporation convection tube bundle is arranged in a reverse flow mode by using H-shaped fins or light tubes, the evaporation convection tube bundle is fixed on the flue guard plate by a support cross beam, the support cross beam is a hollow structure welded by steel plates, cooling air from the outlet of a secondary air fan is introduced into the support cross beam, an adjusting valve is arranged on the cooling air inlet pipeline of the support cross beam, and the outlet is connected to the negative pressure area of the flue before a dust collector. The tube diameter of the evaporation convection tube bundle is Φ76mm*9mm, the material of the tube bundle is 12Cr1MoVG, and appropriate transverse pitch and longitudinal pitch are adopted to control the flow rate and prevent wear.

[0035] The flue is installed on the steel frame 18, the superheater includes a high-temperature superheater 11 and a low-temperature superheater 12; the superheater in the flue is arranged below the evaporation convection tube bundle, the superheater adopts a light tube countercurrent arrangement, the tube bundle of the superheater is fixed on the flue guard plate through a support cross beam, the support cross beam is a hollow structure welded by a steel plate, cooling air from the outlet of the secondary air fan is introduced into the inside, an adjusting valve is arranged on the cooling air inlet pipeline of the support cross beam, and the outlet is connected to the negative pressure area of the flue in front of the dust collector. The tube diameter of the tube bundle of the superheater is Φ76mm*8.5mm, the tube bundle material is T91, and appropriate transverse pitch and longitudinal pitch are adopted to control the flow rate and prevent abrasion.

[0036] The economizer includes a high-temperature economizer 13 and a low-temperature economizer 14; the high-temperature economizer 13 and the low-temperature economizer 14 in the flue are arranged below the superheater, the economizer adopts an H-shaped fin countercurrent arrangement, expansion sealing structures are arranged at the wall-penetrating tube bundles of the economizer, the tube bundle of the economizer is fixed on the flue guard plate through a support cross beam, the support cross beam is a hollow structure welded by a steel plate, cooling air from the outlet of the secondary air fan is introduced into the inside, an adjusting valve is arranged on the cooling air inlet pipeline of the support cross beam, and the outlet is connected to the negative pressure area of the flue in front of the dust collector. The tube diameter of the tube bundle of the economizer is Φ60mm*9mm, the tube bundle material is 20G, and the tube bundle meets the GB / T5310 standard, appropriate transverse pitch and longitudinal pitch are adopted to control the flow rate and prevent abrasion.

[0037] The air preheater includes a secondary air preheater 15 and a primary air preheater 16; the air outlet of the secondary air preheater 15 is connected to the secondary air injection port 20 in the middle of the coil furnace 4; the air outlet of the primary air preheater 16 is connected to the primary air inlet 19 of the coil water-cooled air chamber 3, and the preheater adopts enamel surface treatment.

[0038] The ignition burner 1, the coal feeding device 2, the coil furnace 4, the coil water-cooled air chamber 3 and the material return device 7 form a combustion section; the evaporation convection tube bundle, the superheater, the economizer, the preheater and the energy-saving external energy-saving heat exchanger 17 form a heat exchange section; the coal feeding device 2 includes at least two coal feeding pipes, a coal feeding air pipe and a coal spreading air pipe are arranged on each coal feeding pipe, and one air door is arranged on the air feeding pipe and the coal spreading air pipe.

[0039] The steam-water separation device 5 realizes efficient separation of steam and water, improves the dryness of steam, and maintains the stability of water circulation.

[0040] The material return device 7 is communicated with the coil furnace 4 through a material return pipe; the fly ash separated from the material return device 7 is sent back to the coil furnace 4 for continuous combustion, an air door and a flowmeter are arranged on the material return pipe to adjust the air volume; the center line of the material return port of the material return device 7 is 1300mm higher than the plane of the air distribution plate 21, and the material return pipe adopts a metal expansion joint.

[0041] The coil furnace 4 adopts a spiral winding water-cooled wall pipe; a welding fin and a welding pin structure are adopted on the inner wall of the spiral winding water-cooled wall pipe, and wear-resistant castable is laid; the spiral winding water-cooled wall pipe is formed by winding a plurality of pipes, and the pitch of adjacent pipes is 80 mm.

[0042] The air distribution plate 21 is horizontally arranged at the bottom of the coil furnace 4; a plurality of bell-shaped air caps arranged in a matrix are welded on the upper part of the air distribution plate 21, and the joint between the air cap and the air distribution plate 21 is filled with high-strength wear-resistant castable and medium-quality thermal insulation castable poured in layers;

[0043] The air distribution plate 21 is integrated with two vertical slag discharge pipes; the two vertical slag discharge pipes are connected to a continuous operation slag discharge pipe, an accident slag discharge pipe, a direct-through slag discharge channel, and a quick-opening gate valve; the side of the coil water-cooled air chamber 3 is also provided with an inspection door for maintenance; the steam injection furnace is a vertical structure, and a duct burner is used for under-bed ignition. The combustion system meets the fluidization requirements of ASME PTC4-2013 for CFB boilers.

[0044] Name and Symbol Unit Separator (adiabatic) Upper evaporative convection bank Lower evaporative convection bank Superheater Pipe size mm / Φ76x9 Φ76x9 Φ76x8.5 Convection heating area m2 / 110.6 556.1 445.5 Flue gas inlet temperature ℃ 862 885 771 600 Flue gas outlet temperature ℃ 885 771 600 436.8 Working medium inlet temperature ℃ / 361.9 361.9 361.9 Working medium outlet temperature ℃ / 361.9 361.9 375 Flue gas average velocity m / s / 8.33 9.36 6.1 Working medium average velocity m / s / / / 11.2 Heat transfer coefficient kcal / h.°C.m2 / 32.6 14.6 41.1 Heat balance heat absorption kcal / kg / 286 439.7 427.8 Name and Symbol Unit Upper coal economizer Lower coal economizer Upper air preheater Lower air preheater Pipe size mm Φ60x9 Φ60x9 Φ40x1.5 Φ40x1.5 Convection heating area m2 503 503 247.2 494.3 Flue gas inlet temperature ℃ 436.8 302.9 215.7 183.7 Flue gas outlet temperature ℃ 302.9 215.7 183.7 144.2 Working medium inlet temperature ℃ 115.6 88 20 20.0 Working medium outlet temperature ℃ 157.4 115.6 104.5 127 Flue gas average velocity m / s 5.43 4.65 6.68 6.26 Working medium average velocity m / s 1.85 1.82 8.4 8.7 Heat transfer coefficient kcal / h.°C.m2 15.96 15.34 14 14.1 Heat balance heat absorption kcal / kg 316.7 205.7 78.5 99.7

[0045] Working principle: the fuel is as shown in the table,

[0046] Item Symbol Unit Design coal type Received base low calorific value Q net. ar ]]> KCal / Kg 4450 Elemental analysis Applied base carbon [C ar ]]> % 45.82 Applied base hydrogen H ar ]]> % 4.95 Applied base oxygen O ar ]]> % 13.77 Applied base nitrogen <![CDATA[N ar ]]> % 1.5 Applied base sulfur [SA ar ]] % 0.26 Applied base ash A ar ]]> % 10.84 Applied base water [WC ar ]]> % 22.86

[0047] Fuel particle size requirement: coal is 0-10 mm; 50% cutting particle size d50=1.5 mm; (such as coal) enters the coil furnace 4 through the coal feeding device 2, and the coal feeding device 2 includes at least two coal feeding pipes, each of which is provided with a coal feeding air pipe and a coal spreading air pipe for conveying coal and promoting the uniform distribution of coal in the combustion chamber, respectively;

[0048] The primary air preheater 16 heats the cold air to an appropriate temperature, which enters the air distribution plate 21 through the primary air inlet 19 of the coil water-cooled air chamber 3 to provide fluidized air for the bed layer, ensuring that the coal particles are in a fluidized state in the combustion chamber; the secondary air preheater 15 heats the cold air, which is then sent into the combustion chamber through the secondary air nozzle 20 in the middle of the coil furnace 4 to provide sufficient oxygen for combustion;

[0049] The ignition burner 1 is used to ignite the coal bed; after the temperature of the bed layer rises, the ignition burner 1 is withdrawn, and the combustion is maintained relying on the self-ignition characteristics of the coal; the coal reacts with oxygen in the air at high temperature to generate high-temperature flue gas and solid particles;

[0050] The flue gas generated by the combustion is mixed with the unburned solid particles and enters the cyclone separator 8 at the outlet of the coil furnace 44. The cyclone separator 8 is a high-temperature insulation type, and the inner wall adopts a nail and drag brick frame structure and is covered with wear-resistant refractory materials to prevent erosion and wear.

[0051] The cyclone separator 8 separates the solid particles from the flue gas and returns them to the coil furnace 4 through the return feeder 7 for further combustion. The centerline of the return port of the return feeder 7 is 1300mm above the plane of the air distribution plate 21. The return pipe is equipped with a damper and flow meter to adjust the return volume and air volume.

[0052] The separated flue gas enters the flue and is heated in sequence by the evaporation convection tube bundle, superheater, economizer and air preheater. An external energy-saving heat exchanger 17 is also provided in the flue to further increase the flue gas temperature and improve the subsequent heat exchange efficiency.

[0053] Feed water is pumped into the economizer by a feed water pump, passes through the coil water-cooled air chamber 3, the coil furnace 4, and the evaporative convection tube bundle, absorbs heat from the flue gas, and then enters the steam-water separation device 5. The water absorbs heat from the high-temperature flue gas within the tubes, vaporizing into saturated steam to form a steam-water mixture. The economizer includes a high-temperature economizer and a low-temperature economizer 14, which are arranged in an H-shaped countercurrent configuration to improve heat exchange efficiency. The evaporative convection tube bundle includes an upper-stage evaporative convection tube bundle 9 and a lower-stage evaporative convection tube bundle 10. The evaporative convection tube bundles are arranged in an H-shaped countercurrent configuration or with bare tubes to improve heat exchange efficiency.

[0054] The heated water feed part passes through the external energy-saving heat exchanger 17, and the heat-exchanged water enters the water feed pipe, thereby improving the overall heat exchange efficiency.

[0055] The steam-water separator 5 efficiently separates the steam-water mixture, ensuring that the steam dryness reaches above 99.5%. The steam-water separator 5 maintains the stability of the water circulation and guarantees the steam quality;

[0056] The separated saturated steam enters the superheater of the convection flue and is further heated by the flue gas to the required temperature and pressure to form superheated steam for steam injection in oil fields;

[0057] The flue gas from the furnace passes through the cyclone separator 8, the flue, the evaporative convection tube bundle, the superheater, the economizer, and the air preheater, and is finally discharged through the chimney. After being cooled in the flue by the high-temperature economizer and the low-temperature economizer 14, the flue gas enters the dust collector for dust removal to ensure that the emission meets environmental protection standards.

[0058] The air distribution plate 21 is arranged horizontally at the bottom of the coil furnace 4, and a bell-shaped air hood arranged in a matrix is ​​welded on the upper part. The joint between the air hood and the air distribution plate 21 is filled with layered high-strength wear-resistant refractory castable and medium-quality thermal insulation castable to ensure uniform air distribution;

[0059] The slag discharging pipe is vertically through and connected to the slag cooler and the accident slag discharging pipe, and is directly connected to the slag discharging groove and equipped with a quick opening gate valve, so as to facilitate the maintenance and maintenance;

[0060] The side of the water cooling air chamber 3 is provided with an inspection door for maintenance. All the key components such as the cyclone separator 8, the economizer, the superheater and the evaporation convection tube bundle are made of wear-resistant materials and have optimized structures, so as to prolong the service life.

[0061] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0062] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A coal-fired circulating fluidized bed oilfield steam injection furnace, characterized in that: The furnace comprises a steel frame on which a coil furnace is mounted. The bottom and top of the coil furnace are respectively provided with a coil water-cooled air chamber and a steam-water separation device with a built-in separator. An air distribution plate is provided at the connection between the coil water-cooled air chamber and the coil furnace. An ignition burner is connected to a flange on the rear wall of the coil water-cooled air chamber. A coal feeding device is provided on the side wall of the coil furnace in communication therewith. A cyclone separator is connected to the side wall of the coil furnace near the steam-water separation device. A return feeder connected to the coil furnace is provided at the bottom of the cyclone separator. The top of the cyclone separator is connected to the flue. An evaporative convection tube bundle, a superheater, an economizer and an air preheater are arranged in the flue in sequence according to the direction of flue gas flow. An external energy-saving heat exchanger is connected between the economizer and the preheater.

2. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The cyclone separator is a high-temperature insulated cyclone separator. The inner wall of the cyclone separator adopts a grab nail and drag brick frame structure and is covered with wear-resistant and refractory materials. The cyclone separator is arranged at the outlet of the coil furnace. The flue gas temperature at the inlet of the cyclone separator is 850-950°C. Non-metallic expansion joints are used at the outlet of the coil furnace and the inlet of the cyclone separator. The solid particles separated by the cyclone separator are returned to the furnace through the return feeder; the separated flue gas enters the flue and heats the rear heating surface.

3. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The flue is installed on a steel frame, and the evaporative convection tube bundle includes an upper evaporative convection tube bundle and a lower evaporative convection tube bundle; the evaporative convection tube bundle adopts an H-shaped fin or light tube countercurrent arrangement, and the evaporative convection tube bundle is fixed to the flue guard plate through a supporting crossbeam. The supporting crossbeam is a hollow structure welded with steel plates, and cooling air from the secondary fan outlet is introduced into the interior. The cooling air inlet pipe of the supporting crossbeam is provided with a regulating valve, and the outlet is connected to the negative pressure area of ​​the flue in front of the dust collector.

4. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The flue is installed on a steel frame, and the superheater includes a high-temperature superheater and a low-temperature superheater; the superheater in the flue is arranged below the evaporative convection tube bundle, and the superheater adopts a light tube countercurrent arrangement. The tube bundle of the superheater is fixed to the flue guard plate through a supporting beam. The supporting beam is a hollow structure welded with steel plates, and cooling air from the secondary fan outlet is introduced into the interior. The cooling air inlet pipe of the supporting beam is provided with a regulating valve, and the outlet is connected to the negative pressure area of ​​the flue in front of the dust collector.

5. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The economizer includes a high-temperature economizer and a low-temperature economizer; the high-temperature economizer and the low-temperature economizer in the flue are arranged below the superheater, and the economizer adopts an H-shaped fin countercurrent arrangement. The through-wall tube bundles of the economizer are provided with an expansion sealing structure. The tube bundles of the economizer are fixed to the flue guard plate through a supporting beam. The supporting beam is a hollow structure welded with steel plates. Cooling air from the secondary fan outlet is introduced into the interior. The cooling air inlet pipe of the supporting beam is provided with a regulating valve, and the outlet is connected to the negative pressure area of ​​the flue in front of the dust collector.

6. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The air preheater includes a secondary air preheater and a primary air preheater; the air outlet of the secondary air preheater is connected to the secondary air nozzle in the middle of the coil furnace; the air outlet of the primary air preheater is connected to the primary air inlet of the coil water-cooled air chamber, and the preheater adopts enamel surface treatment.

7. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The ignition burner, coal feeding device, coil furnace, coil water-cooled air chamber and return feeder constitute the combustion section; the evaporative convection tube bundle, superheater, economizer, preheater and energy-saving external energy-saving heat exchanger constitute the heat exchange section; the coal feeding device includes at least two coal feeding pipes, each of which is provided with a coal feeding air duct and a coal spreading air duct, and the air supply pipe and coal spreading air duct are both provided with an air damper.

8. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The returner is connected to the coil furnace through a return pipe; the fly ash separated by the returner is sent back to the coil furnace for further combustion, and the return pipe is provided with an air damper and a flow meter for adjusting the air volume; the center line of the return port of the returner is 1300mm higher than the plane of the air distribution plate, and the return pipe adopts a metal expansion joint.

9. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The coil furnace adopts a spirally wound water-cooled wall tube; the inner wall of the spirally wound water-cooled wall tube adopts a welded fin and welded pin structure, and is laid with wear-resistant castable. The spirally wound water-cooled wall tube is formed by winding multiple tubes, and the pitch between adjacent tubes is 80mm.

10. The coal-fired circulating fluidized bed oilfield steam injection furnace according to claim 1, characterized in that: The air distribution plate is arranged horizontally at the bottom of the coil furnace; bell-shaped air caps arranged in a matrix are welded to the upper part of the air distribution plate, and the joints between the air caps and the air distribution plate are filled with high-strength wear-resistant castables and medium-quality thermal insulation castables poured in layers; The air distribution plate is integrated with two vertical slag discharge pipes, which are composed of a continuously running slag discharge pipe connected to a slag cooler and an emergency slag discharge pipe, directly connected to a slag discharge ditch and equipped with a quick-opening gate valve; an inspection door is also arranged on the side of the coil water-cooled air chamber, and the steam injection furnace is a vertical structure, which adopts an air duct burner for under-bed ignition.

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