High-capacity subcritical coal-fired CFB type oil field steam-injection boiler

Abstract

The invention relates to the field of oil field steam injection boiler equipment, in particular to a high-capacity subcritical coal-fired CFB type oil field steam injection boiler, the highest pressure of the boiler can reach subcritical pressure, the boiler comprises a steel frame, and a boiler barrel, a hearth water cooling wall and a flue are arranged on the steel frame. A superheater, an upper-level economizer, SCR equipment, a lower-level economizer and an air preheater are sequentially arranged on the flue, a softened water pipeline used for conveying oilfield sewage is arranged on the steel frame, the softened water pipeline is sequentially communicated with the lower-level economizer, the upper-level economizer and a bottom coil pipe of a hearth water cooling wall, and the middle and a top coil pipe of the hearth water cooling wall are communicated with a boiler barrel. A separating assembly used for separating saline water and steam is arranged in the boiler barrel, a steam pipeline is communicated between the top of the boiler barrel and the superheater, the bottom of the boiler barrel is communicated with a salt discharging pipe, and a pressure measuring piece used for monitoring pressure changes in a coil pipe is arranged on the coil pipe of the hearth water cooling wall. The method has the effect of reducing the equipment investment cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield steam injection boiler equipment, in particular to a large-capacity subcritical coal-fired CFB type oilfield steam injection boiler. BACKGROUND

[0002] The oilfield steam injection boiler is a boiler equipment widely used in the process of oilfield exploitation, which is used to inject high-pressure high-temperature steam into the oil well to heat the crude oil in the oil layer to reduce the viscosity of the heavy oil, thereby increasing the flowability of the heavy oil and greatly improving the recovery rate of the heavy oil.

[0003] The oilfield steam injection boiler is divided into two modes of burning natural gas and burning coal according to the fuel. Since the input cost of natural gas is high and the economy is poor, it is gradually eliminated. Among the coal-fired modes, there are ordinary coal-fired CFB boilers and small-scale once-through CFB boilers.

[0004] For the ordinary coal-fired CFB boiler, the water quality of the boiler is required to be high during use. The boiler feed water must reach the water quality standard of the power station boiler. However, due to the actual conditions of the oilfield operation area, the oilfield area can only provide the oilfield sewage (oilfield softened water) which has been preliminarily treated. Therefore, it is necessary to set up a complex water treatment equipment, and the equipment investment and operation cost are very high. Moreover, once the water quality changes, the boiler may have a pipe explosion accident in a short time, and many oilfield mine areas do not have the conditions to provide tap water or river surface water and underground water. For the small-scale once-through CFB boiler, although the oilfield sewage (oilfield softened water) can be directly used, the heating surface (the pipeline for conveying sewage) in the boiler will have a serious salt accumulation and scaling phenomenon. Long-time operation is also prone to pipe explosion accidents. The traditional solution is to regularly disassemble and clean and maintain, and the maintenance time is usually long. Therefore, regular cleaning is prone to problems such as too much salt accumulation and scaling in the heating surface (the pipeline for conveying sewage) in the boiler, even pipe explosion, or too little salt accumulation and scaling, which wastes a lot of production time of the equipment and has defects. SUMMARY

[0005] In order to improve the problems existing in the use of the coal-fired CFB boiler, the present application provides a large-capacity subcritical coal-fired CFB type oilfield steam injection boiler.

[0006] The large-capacity subcritical coal-fired CFB type oilfield steam injection boiler provided by the present application adopts the following technical scheme: The utility model provides a kind of large capacity subcritical coal-fired CFB type oilfield steam injection boiler, including steel frame, the steel frame is provided with boiler barrel, furnace water cooling wall and flue, the furnace water cooling wall is provided with air distribution plate and secondary air device, the flue is sequentially arranged with superheater, upper coal economizer, SCR equipment, lower coal economizer and air preheater, the bottom of the furnace water cooling wall is provided with the feeding device for conveying coal, between the top outlet of the furnace water cooling wall and the flue is provided with expansion joint, between the flue and the expansion joint is provided with dust separator for separating dust and air in flue gas, between the dust separator and the furnace water cooling wall is provided with return device, the return device is used to transport dust separated by the dust separator to the bottom of the furnace water cooling wall, the steel frame is provided with softened water pipeline for conveying oilfield sewage, the softened water pipeline sequentially communicates lower coal economizer, upper coal economizer and the bottom coil of the furnace water cooling wall, the top coil of the furnace water cooling wall is communicated with the boiler barrel, the boiler barrel is provided with separation assembly for separating brine and steam, the top of the boiler barrel is communicated with steam pipeline between the superheater, the bottom of the boiler barrel is communicated with salt discharge pipe, the main steam outlet pipeline of the superheater is provided with water spray desuperheater, the salt discharge pipe is communicated with the water spray desuperheater, the water spray desuperheater is communicated to oil well by pipeline, the coil of the furnace water cooling wall is provided with pressure measuring element for monitoring pressure change in coil.

[0007] By adopting the above technical scheme, oilfield sewage flows through lower coal economizer and upper coal economizer in turn through softened water pipeline, and then flows into boiler barrel through bottom coil of furnace water cooling wall and top coil of furnace water cooling wall, while coal conveyed by feeding device is combusted in furnace water cooling wall, high-temperature flue gas after separation by dust separator is discharged through flue, separated dust returns to furnace water cooling wall for secondary combustion under the action of return device, while heat on high-temperature air after removing dust is absorbed by oilfield sewage flowing through lower coal economizer and upper coal economizer, high-temperature and high-pressure steam flowing into boiler barrel is separated into brine and steam by separation assembly, high-concentration brine at the bottom of boiler barrel flows to water spray desuperheater through salt discharge pipe, while high-temperature and high-pressure steam after removing brine flows to superheater through steam pipeline to be heated again, while high-temperature and high-pressure steam after heating by superheater is transported to oil well through pipeline after temperature reduction by high-concentration brine sprayed by water spray desuperheater, so as to solve the problem of high-concentration brine and reduce the impact on environment, while in the process, pressure measuring element feeds back pressure change in coil of furnace water cooling wall at any time, when salt accumulation and scaling in coil of furnace water cooling wall are serious, pressure in coil of furnace water cooling wall will increase under the condition that input pressure of softened water pipeline and output pressure of boiler barrel are unchanged, when the pressure fed back by pressure measuring element exceeds designed safety pressure, equipment can be accurately maintained at this time, which greatly reduces the cost of equipment maintenance.

[0008] Optionally, the pressure measuring element comprises a plurality of pressure sensors arranged on the coils of the furnace water wall, and the pressure sensors are electrically connected to the control system.

[0009] By using the above technical scheme, the plurality of pressure sensors can feed back the pressure changes of the coils at different positions of the furnace water wall to the control system, and the control system can indirectly monitor the salt accumulation and scaling in the coils of the furnace water wall by analyzing the information fed back by the plurality of pressure sensors, thereby facilitating workers to accurately control the time for maintaining the furnace water wall and greatly reducing the maintenance cost.

[0010] Optionally, the furnace water wall comprises a bottom water wall, a middle water wall and an upper water wall, and a dismounting plate is arranged between the middle water wall and the bottom water wall and between the middle water wall and the upper water wall, and a dismounting straight pipe is in communication between the coils on the middle water wall and the coils on the bottom water wall and between the coils on the middle water wall and the coils on the upper water wall.

[0011] By using the above technical scheme, when the equipment needs to be transferred, the workers can cut off the dismounting plate and the dismounting straight pipe to split the entire furnace water wall into the bottom water wall, the middle water wall and the upper water wall, thereby facilitating subsequent transfer and transportation, and at a later stage, the bottom water wall, the middle water wall and the upper water wall can be reassembled into an integral whole by welding the dismounting plate and the dismounting straight pipe, thereby solving the problem of inconvenient transportation of the large furnace water wall.

[0012] Optionally, the separation assembly comprises a steam-water separator arranged in the drum, the coils on the furnace water wall are connected to an inlet end of the steam-water separator, a steam outlet end of the steam-water separator is located above a liquid level in the drum, a liquid level sensor electrically connected to the control system is arranged on the drum, a blowdown baffle is arranged at a bottom of the drum, a plurality of holes are formed in the blowdown baffle, a liquid discharge valve at a bottom of the steam-water separator is located below the blowdown baffle, and a communication position of the salt discharge pipe with the drum is located below the blowdown baffle.

[0013] By using the above technical scheme, the high-temperature and high-pressure steam flowing out of the coils at the top of the furnace water wall is separated by the steam-water mixture in the separator, the steam in the mixture flows to the inner top of the drum, the salt water in the steam flows to the inner bottom of the drum, the holes in the blowdown baffle isolate the impurities in the salt water flowing out of the bottom of the steam-water separator, and the impurities flowing to the inner bottom of the drum are discharged from the drum through the salt discharge pipe, thereby achieving the effect of continuous separation of the salt water and the air.

[0014] Optionally, a filter screen is arranged in the drum and located below the communication position of the steam pipeline with the drum.

[0015] By adopting the technical scheme, the filter screen further filters the salt-containing water vapor floating in the drum, so that the salt content of the steam flowing to the superheater is further reduced, and the possibility of damage of the superheater by the salt-containing steam is reduced.

[0016] Optionally, the drum is horizontally placed, a plurality of vertical guide columns are uniformly arranged around the inside of the drum, a needle plate is jointly and slidingly arranged on the plurality of guide columns, a plurality of vertical sparse-hole needles are arranged on the needle plate, the sparse-hole needles correspond to the holes one by one, the sparse-hole needles are used for inserting into the holes, and a dredging piece is arranged on the drum and used for driving the needle plate to vertically reciprocatingly slide.

[0017] By adopting the technical scheme, when the high-concentration salt water at the bottom of the drum is crystallized on the holes of the blowdown baffle, the dredging piece drives the needle plate to vertically reciprocatingly slide, the vertically sliding needle plate drives the sparse-hole needles to reciprocatingly insert into and pull out the holes of the blowdown baffle, so that the holes of the blowdown baffle are dredged, and the possibility that the holes of the blowdown baffle are blocked and the drum cannot work normally is reduced.

[0018] Optionally, the dredging piece comprises an outer pipe communicated with the bottom of the drum, one end of the salt discharge pipe is sleeved at the bottom end of the outer pipe, a vertical rod coaxial with the outer pipe is vertically slidingly arranged on the blowdown baffle, a hollow floating ball is arranged at the top of the vertical rod, a limiting cone is arranged at the bottom of the vertical rod, the diameter of the limiting cone gradually decreases along the direction from the vertical rod to the floating ball, the conical surface of the limiting cone is used for abutting against the end edge of the outer pipe, an installation plate is arranged on the vertical rod away from the floating ball on the blowdown baffle, an arc rod is rotationally arranged on the inside of the end of the drum along the axis of the drum, the center of the arc of the arc rod is located on the axis of the drum, the arc rod is symmetrically arranged about the axis of the vertical rod, a connecting rod is hingedly connected between the installation plate and the arc rod, a supporting block is arranged at one end of the arc rod away from the connecting rod and below the needle plate, the supporting block is used for abutting against the lower surface of the needle plate, a side flow port is arranged on the blowdown baffle, a vertical guide column is arranged on the needle plate and slidingly passes through the blowdown baffle, and a sealing plate is arranged on the guide column away from the needle plate on the blowdown baffle and used for sealing the side flow port.

[0019] By adopting the technical scheme, when the pipeline valve on the salt discharge pipe is closed, at this time, the salt water in the salt discharge pipe cannot be discharged, the needle plate separates the perforated needle from the blow-off baffle under the action of gravity, the sealing plate blocks the side flow port on the blow-off baffle, the float rises under the action of the buoyancy of the liquid in the kettle drum, the vertical rod drives the arc rod to rotate and descend through the connecting rod, the taper surface of the limiting cone abuts against the edge of the outer pipe, at this time, the outer pipe is blocked, when the pipeline valve on the salt discharge pipe is opened, the pressure in the salt discharge pipe decreases, the high pressure in the kettle drum makes the limiting cone separate from the edge of the outer pipe, the high-concentration salt water at the bottom of the kettle drum flows to the salt discharge pipe through the outer pipe, the liquid level in the kettle drum decreases, and the salt water flowing out of the outer pipe will impact the limiting cone, so that the vertical rod descends, the arc rod is driven to rotate through the connecting rod, the arc rod drives the supporting block to rise and push the needle plate, the needle plate drives the guide column and the perforated needle to rise synchronously, the guide column drives the sealing plate to open the side flow port, the perforated needle rises to unblock the holes on the blow-off baffle, and the cleaned crystals in the holes flow to the outer pipe through the side flow port on the blow-off baffle, so that the possibility of secondary blocking of the holes on the blow-off baffle is reduced.

[0020] Optionally, a plurality of arc rods are uniformly arranged along the axis direction of the kettle drum, a plurality of scraping rods are arranged between the arc rods on the side away from the axis of the vertical rod, the plurality of scraping rods are uniformly arranged on the arc rods along the axis of the kettle drum, the connecting rod is connected to one of the arc rods, and the scraping rod is attached to the inner side wall of the kettle drum.

[0021] By adopting the technical scheme, the scraping rod on the arc rod can scrape the crystalline salt on the bottom wall of the kettle drum in the sliding process of the arc rod, so that the bottom side wall of the kettle drum is automatically cleaned, and the frequency of worker maintenance is reduced.

[0022] In summary, the present application has at least one of the following beneficial technical effects: 1. The pressure measuring part can feedback the pressure change in the coil of the furnace water cooling wall at any time, when the salt and scale in the coil of the furnace water cooling wall are serious, the pressure in the coil of the furnace water cooling wall will increase under the condition that the input pressure of the softening water pipe and the output pressure of the kettle drum are constant, when the pressure feedback by the pressure measuring part exceeds the designed safety pressure, the equipment can be accurately maintained at this time, and the cost of equipment maintenance is greatly reduced. 2. When the equipment needs to be transferred, the worker can cut off the disassembly plate and the disassembly straight pipe to split the entire furnace water cooling wall into three parts, i.e., the bottom water cooling wall, the middle water cooling wall and the upper water cooling wall, so that the subsequent transfer and transportation are facilitated, and the bottom water cooling wall, the middle water cooling wall and the upper water cooling wall can be reassembled into an integral whole by welding the disassembly plate and the disassembly straight pipe, so that the problem of inconvenient transportation of the large-scale furnace water cooling wall is solved. 3. When the pipe valve on the salt discharge pipe is opened, the pressure in the salt discharge pipe decreases, the high pressure in the kettle cylinder causes the limiting cone to be separated from the edge of the outer pipe, the high-concentration brine at the bottom of the kettle cylinder flows from the outer pipe to the salt discharge pipe, the liquid level in the kettle cylinder decreases, and the brine flowing out of the outer pipe will impact the limiting cone, causing the vertical rod to drop, the dropping vertical rod pushes the arc rod to rotate through the connecting rod, the arc rod drives the supporting block to rise and push the needle plate, the needle plate will drive the guide column and the perforating needle to rise synchronously, the guide column will drive the sealing plate to open the side flow port, and the perforating needle will rise to unblock the holes on the pollution discharge baffle, the cleaned crystals in the holes will flow to the outer pipe through the side flow port on the pollution discharge baffle, thereby reducing the possibility of secondary blockage of the holes on the pollution discharge baffle. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of embodiment 1 of the present application.

[0024] Figure 2 is Figure 1 is a sectional view along A-A in

[0025] Figure 3 is a sectional view for embodying the positional relationship of the disassembly plate, the disassembly straight pipe and the pressure sensor in embodiment 1 of the present application.

[0026] Figure 4 is a sectional view for embodying the positional relationship of the steam-water separator, the pollution discharge baffle and the filter screen in embodiment 1 of the present application.

[0027] Figure 5 is a sectional view for embodying the positional relationship of the floating ball, the vertical rod and the outer pipe in embodiment 2 of the present application.

[0028] Figure 6 is a sectional view for embodying the positional relationship of the scraping rod, the arc rod and the needle plate in embodiment 2 of the present application.

[0029] Explanation of reference numerals: 1, steel frame; 2, drum; 3, furnace water cooling wall; 31, bottom water cooling wall; 32, middle water cooling wall; 33, upper water cooling wall; 34, dismounting plate; 35, dismounting straight pipe; 4, flue; 5, air distribution plate; 6, secondary air device; 7, superheater; 8, upper coal economizer; 9, SCR device; 10, lower coal economizer; 11, air preheater; 12, feeding device; 13, expansion joint; 14, dust separator; 15, return device; 16, soft water pipeline; 17, separation assembly; 171, steam-water separator; 172, liquid level sensor; 173, blowdown partition; 174, hole; 18, steam pipeline; 19, salt discharge pipe; 20, water spray attemperator; 21, pressure sensor; 22, filter screen; 23, guide column; 24, needle plate; 25, perforating needle; 26, unblocking member; 2601, outer tube; 2602, vertical rod; 2603, floating ball; 2604, limiting cone; 2605, mounting plate; 2606, arc rod; 2607, connecting rod; 2608, supporting block; 2609, side flow port; 2610, guide column; 2611, sealing plate; 27, scraping rod; 28, limiting block; 29, ignition device; 40, slag falling pipe; 41, water-cooled air chamber; 42, middle blowdown pipe. DETAILED DESCRIPTION

[0030] The drawings will be described below in detail Figures 1-6 The application is further described in detail.

[0031] Embodiment 1 The embodiment of the application discloses a large-capacity subcritical coal-fired CFB type oilfield steam injection boiler.

[0032] Referring to Figure 1 A large-capacity subcritical coal-fired CFB type oilfield steam injection boiler comprises a steel frame 1, the steel frame 1 is composed of a plurality of sheet steels which are bolted and combined together, a drum 2, a furnace water cooling wall 3 and a flue 4 are bolted to the steel frame 1, an air distribution plate 5 and a secondary air device 6, an ignition device 29 and a slag falling pipe 40 are installed at the bottom of the furnace water cooling wall 3, the ignition device 29 and the bottom of the furnace water cooling wall 3 are communicated to form a water-cooled air chamber 41, and the coil on the furnace water cooling wall 3 is arranged in a spiral shape.

[0033] Referring to Figure 1 The superheater 7, the upper coal economizer 8, the SCR device 9, the lower coal economizer 10 and the air preheater 11 are sequentially arranged on the flue 4 from top to bottom, a plurality of groups of the upper coal economizer 8 and the lower coal economizer 10 are arranged on the steel frame 1, a feeding device 12 for conveying coal is arranged at the bottom of the furnace water cooling wall 3, and an expansion joint 13 is welded between the top outlet of the furnace water cooling wall 3 and the flue 4.

[0034] Referring to Figure 1, the flue 4 and expansion joint 13 between the bolted for separating the smoke and air dust dust separator 14, the bottom of the dust separator 14 and the boiler water wall 3 between the arrangement of the return device 15, the return device 15 for the bottom of the dust separator 14 after separating the dust to the bottom of the boiler water wall 3.

[0035] Referring to Figure 1 and Figure 2 , the steel frame 1 bolted for transporting oilfield sewage softened water pipeline 16, the softened water pipeline 16 in turn communicates with the lower stage economizer 10, the upper stage economizer 8 and the bottom of the boiler water wall 3 coil, the middle and top of the boiler water wall 3 coil is connected to the drum 2.

[0036] Referring to Figure 1 , Figure 3 and Figure 4 , the top of the drum 2 and the superheater 7 are communicated with the steam pipe 18, the bottom of the drum 2 is communicated with the salt discharge pipe 19, the salt discharge pipe 19 is connected with the pipe valve (not shown in the figure) electrically connected to the control system, the main steam outlet pipe of the superheater 7 is connected with the water spray desuperheater 20, the salt discharge pipe 19 is communicated with the water spray desuperheater 20, the superheated steam flowing out of the superheater 7 is cooled by the salt water flowing out of the salt discharge pipe 19 in the water spray desuperheater 20 and then transported to the oil well through the pipe, and the coil of the boiler water wall 3 is provided with a pressure measuring element for monitoring the pressure change in the coil.

[0037] Referring to Figure 3 , the pressure measuring element comprises a plurality of pressure sensors 21 bolted to the outer side of the boiler water wall 3, the pressure sensor 21 can adopt the high temperature and high pressure resistant pressure sensor 21 in the prior art, the sensing end of the pressure sensor 21 extends into the coil on the boiler water wall 3, the pressure sensor 21 is electrically connected to the control system, and the pressure sensor 21 can also be replaced by the high temperature and high pressure resistant pressure gauge in the prior art.

[0038] The feeding device 12 delivers the coal to the bottom of the boiler water wall 3, the ignition device 29 ignites the coal, the air distribution plate 5 and the secondary air device 6 deliver air into the boiler water wall 3, the flue gas of the coal combustion in the boiler water wall 3 flows to the dust separator 14 through the expansion joint 13, the dust separator 14 separates the dust in the flue gas, and the return device 15 delivers the separated dust into the boiler water wall 3 again for secondary incineration.

[0039] The air separated by the dust separator 14 flows to the flue 4, and flows from the top to the bottom of the flue 4, in the process, the SCR device 9 harmless treatment of tail gas, and the oilfield sewage is pumped into the softened water pipeline 16 by the high pressure pump, and the oilfield sewage in the softened water pipeline 16 absorbs the heat in the tail gas when flowing through the lower stage economizer 10 and the upper stage economizer 8 in turn.

[0040] The heat is absorbed by the bottom coil of the furnace water cooling wall 3, and then is absorbed by the inner layer spiral coil of the furnace water cooling wall 3, and then flows into the drum 2 through the top coil of the furnace water cooling wall 3. In this process, the pressure sensor 21 feeds back the pressure change of the multiple coils at any time.

[0041] With reference to Figure 1 and Figure 4 , the furnace water cooling wall 3 comprises a bottom water cooling wall 31, a middle water cooling wall 32 and an upper water cooling wall 33. The middle water cooling wall 32 is welded with a detachable plate 34 between the bottom water cooling wall 31 and the middle water cooling wall 32, and between the middle water cooling wall 32 and the upper water cooling wall 33. The coil on the middle water cooling wall 32 is communicated with the coil on the bottom water cooling wall 31, and the coil on the middle water cooling wall 32 is communicated with the coil on the upper water cooling wall 33 through a detachable straight pipe 35.

[0042] With reference to Figure 4 , the drum 2 is arranged with a separation assembly 17 for separating brine and steam. The separation assembly 17 comprises a steam-water separator 171 welded in the drum 2. The coil on the furnace water cooling wall 3 is connected to the inlet end of the steam-water separator 171. The gas outlet end of the steam-water separator 171 is located above the liquid level in the drum 2. The drum 2 is bolted with a liquid level sensor 172 electrically connected to the control system.

[0043] With reference to Figure 4 , the drum 2 is welded with a blowdown baffle 173 at the bottom. A plurality of holes 174 are vertically arranged on the blowdown baffle 173. The liquid outlet valve at the bottom of the steam-water separator 171 is located below the blowdown baffle 173. The communication position of the salt discharge pipe 19 and the drum 2 is located below the blowdown baffle 173.

[0044] With reference to Figure 4 , the drum 2 is welded with a filter screen 22 at the top. The filter screen 22 is located below the communication position of the steam pipeline 18 and the drum 2. The drum 2 is communicated with a middle blowdown pipe 42. The top of the middle blowdown pipe 42 is lower than the top of the steam-water separator 171. The middle blowdown pipe 42 is connected with a liquid level valve electrically connected to the control system (not shown in the figure).

[0045] The middle blowdown pipe 42 can discharge the brine in the drum 2. Through the cooperation of the liquid level sensor 172 and the middle blowdown pipe 42, the liquid level in the drum 2 can be effectively controlled to be always at a safe height. The possibility that the water level of the steam-water separator 171 is difficult to control under the load operation of the drum 2, causing a large amount of saturated water to enter the superheater 7 with the saturated steam, is reduced. The safety of the superheater 7 is ensured. At the same time, the dryness value of the main steam at the outlet of the drum 2 can be conveniently and timely regulated, so as to adapt to the requirements of oilfield mines on steam.

[0046] The high-temperature and high-pressure steam-water mixture flowing into the boiler drum 2 is separated by a steam-water separator 171. The steam in the mixture flows to the top of the boiler drum 2, while the brine in the steam flows to the bottom of the boiler drum 2. The filter screen 22 filters the steam flowing to the steam pipe 18 again, and the filtered steam flows to the superheater 7 through the steam pipe 18.

[0047] The holes 174 on the drain baffle 173 will isolate the impurities in the brine flowing out from the bottom of the steam-water separator 171. The impurities flowing to the bottom of the boiler drum 2 will flow to the water spray desuperheater 20 through the salt discharge pipe 19. The high-temperature brine sprayed by the water spray desuperheater 20 and the high-temperature and high-pressure steam discharged from the superheater 7 are injected into the oil well together. Under the condition that the pressure of the oilfield sewage input into the softened water pipe 16 remains unchanged and the discharge pressure inside the boiler drum 2 remains unchanged.

[0048] When the salt and scale buildup in the coils of the furnace water-cooled wall 3 is severe, the pressure inside the coils of the furnace water-cooled wall 3 will increase. Moreover, the heating and salt and scale buildup conditions of each coil are not the same, so the pressure values ​​fed back by the pressure sensor 21 at different locations will be different.

[0049] The control system can accurately detect the salt accumulation and scaling inside the coil by analyzing the pressure values ​​fed back by multiple pressure sensors 21. When the pressure fed back by the pressure sensor 21 exceeds the designed safe pressure, the control system can promptly remind the workers to perform maintenance.

[0050] The implementation principle of Example 1 is as follows: the feeding device 12 delivers coal to the bottom of the furnace water-cooled wall 3, the ignition device 29 ignites the coal, the air distribution plate 5 and the secondary air device 6 deliver air into the furnace water-cooled wall 3, the flue gas from the coal combustion in the furnace water-cooled wall 3 flows to the dust separator 14 through the expansion joint 13, the dust separator 14 separates the dust in the flue gas, and the return material device 15 delivers the separated dust back into the furnace water-cooled wall 3 for secondary combustion.

[0051] After being separated by the dust separator 14, the air flows to the flue 4, from the top to the bottom. During this process, the SCR device 9 treats the exhaust gas to render it harmless. Meanwhile, the oilfield wastewater is pumped into the softened water pipe 16 by a high-pressure pump. The oilfield wastewater in the softened water pipe 16 absorbs heat from the exhaust gas as it flows through the lower economizer 10 and the upper economizer 8.

[0052] The heat is then absorbed by the bottom coil of the furnace water-cooled wall 3 through the layers of spiral coils inside the furnace water-cooled wall 3, and then flows into the boiler drum 2 through the top coil of the furnace water-cooled wall 3. During this process, the pressure sensor 21 constantly feeds back the pressure changes on multiple coils.

[0053] The middle blowdown pipe 42 can discharge the brine in the drum 2. Through the cooperation of the liquid level sensor 172 and the middle blowdown pipe 42, the liquid level in the drum 2 can be effectively controlled to be always at a safe height. The water level of the steam-water separator 171 is difficult to control under the load operation of the drum 2, which may cause the possibility that a large amount of saturated water is carried into the superheater 7 by the saturated steam, thereby ensuring the safety of the superheater 7. At the same time, the dryness value of the main steam at the outlet of the drum 2 can be conveniently and timely regulated to adapt to the requirements of the oil field mine on the steam.

[0054] The high-temperature and high-pressure steam-water mixture flowing into the drum 2 flows to the inner top of the drum 2 under the action of the steam-water separator 171, and the brine in the steam flows to the inner bottom of the drum 2. The filter screen 22 filters the steam flowing to the steam pipeline 18 again, and the filtered steam flows to the superheater 7 through the steam pipeline 18.

[0055] The hole 174 on the blowdown partition plate 173 isolates the impurities in the brine flowing out of the bottom of the steam-water separator 171, and the impurities flowing to the inner bottom of the drum 2 flow to the water spray desuperheater 20 through the brine discharge pipeline 19. The high-temperature brine sprayed by the water spray desuperheater 20 is injected into the oil well together with the high-temperature and high-pressure steam discharged by the superheater 7.

[0056] When the salt accumulation and scaling in the coil of the furnace water wall 3 are serious, the pressure in the coil of the furnace water wall 3 will increase, and the heating and salt accumulation and scaling of each coil are different. Therefore, the pressure values fed back by the pressure sensors 21 at different positions are different.

[0057] The control system can accurately detect the salt accumulation and scaling in the coil by analyzing the pressure values fed back by the multiple pressure sensors 21. When the pressure fed back by the pressure sensor 21 exceeds the designed safety pressure, the control system can timely remind the worker to maintain.

[0058] Embodiment 2 With reference to Figure 5 and Figure 6 The difference between this embodiment and embodiment 1 is that the drum 2 is horizontally placed, and a plurality of vertical guide columns 23 are uniformly welded on the periphery in the drum 2. A needle plate 24 is slidably sleeved on the multiple guide columns 23, a plurality of vertical perforated needles 25 are welded on the upper surface of the needle plate 24, the perforated needles 25 correspond to the holes 174 one by one, and the perforated needles 25 are used for inserting into the holes 174.

[0059] With reference to Figure 5 and Figure 6, the outer tube 2601 is communicated with the bottom of the drum 2, the salt discharge pipe 19 is sleeved and welded to the bottom end of the outer tube 2601, and the vertical rod 2602 coaxial with the outer tube 2601 is arranged on the blowdown baffle 173 in a vertical sliding mode.

[0060] With reference to Figure 5 and Figure 6 , the top of the vertical rod 2602 is welded with the hollow floating ball 2603, the bottom of the vertical rod 2602 is integrally formed with the limiting cone 2604, the diameter of the limiting cone 2604 gradually decreases along the direction of the vertical rod 2602 to the floating ball 2603, the conical surface of the limiting cone 2604 is used for abutting against the inner side edge of the bottom end of the outer tube 2601, and the mounting plate 2605 is welded to the vertical rod 2602 on the side, away from the floating ball 2603, of the blowdown baffle 173.

[0061] With reference to Figure 5 and Figure 6 , the inner side of the end of the drum 2 is rotationally connected with the arc rod 2606 along the axis of the drum 2, the inner side wall of the drum 2 is welded with the limiting block 28 for the arc rod 2606 to slide through, the limiting block 28 is arranged at both ends of the length direction of the arc rod 2606, and the arc center of the arc rod 2606 is located on the axis of the drum 2.

[0062] With reference to Figure 5 and Figure 6 , the arc rods 2606 at the same end of the drum 2 are symmetrically arranged about the axis of the vertical rod 2602, the connecting rod 2607 is hingedly connected between the mounting plate 2605 and the arc rod 2606, the supporting block 2608 is welded to the end, away from the connecting rod 2607, of the arc rod 2606 and located below the needle plate 24, and the supporting block 2608 is used for abutting against the lower surface of the needle plate 24.

[0063] With reference to Figure 5 and Figure 6 , the side flow ports 2609 are formed on the two sides of the blowdown baffle 173, the vertical guide column 2610 is welded to the needle plate 24 in a vertical mode, the guide column 2610 slides through the blowdown baffle 173, and the sealing plate 2611 is welded to the guide column 2610 on the side, away from the needle plate 24, of the blowdown baffle 173 and is used for sealing the side flow ports 2609.

[0064] With reference to Figure 5 and Figure 6 , a plurality of arc rods 2606 are uniformly arranged along the axis direction of the drum 2, the plurality of arc rods 2606 on the side, away from the axis of the vertical rod 2602, of the connecting rod 2607 are commonly welded with the plurality of scraping rods 27, the plurality of scraping rods 27 are uniformly arranged on the arc rod 2606 in a circumferential mode along the axis of the drum 2, the connecting rod 2607 is connected to one of the arc rods 2606, and the scraping rod 27 is attached to the inner side wall of the drum 2.

[0065] When the pipeline valve on the salt discharge pipe 19 is closed, at this time, the brine in the salt discharge pipe 19 cannot be discharged, and the liquid in the kettle drum 2 continues to increase, the floating ball 2603 drives the vertical rod 2602 to rise under the buoyancy of the liquid in the kettle drum 2, the vertical rod 2602 drives the arc rod 2606 to rotate and descend through the connecting rod 2607, the supporting block 2608 is away from the needle plate 24, and the conical surface of the limiting cone 2604 abuts against the edge of the outer pipe 2601, at this time, the outer pipe 2601 is blocked.

[0066] And the needle plate 24 separates the perforated needle 25 from the pollution isolation plate 173, at this time, the sealing plate 2611 blocks the side flow port 2609 on the pollution isolation plate 173, until the liquid level sensor 172 is triggered, at this time, when the pipeline valve on the salt discharge pipe 19 is opened, the pressure in the salt discharge pipe 19 decreases, and the liquid in the salt discharge pipe 19 is discharged, and the high pressure in the kettle drum 2 makes the limiting cone 2604 separate from the edge of the outer pipe 2601.

[0067] The high-concentration brine at the bottom of the kettle drum 2 flows quickly from the outer pipe 2601 to the salt discharge pipe 19, and the liquid level in the kettle drum 2 drops quickly, and the brine flowing out of the outer pipe 2601 will impact the limiting cone 2604 to descend, so that the vertical rod 2602 quickly descends, and the vertical rod 2602 pushes the arc rod 2606 to rotate through the connecting rod 2607, and the arc rod 2606 drives the scraper 27 to remove the crystalline salt on the bottom wall of the kettle drum 2, and the supporting block 2608 on the arc rod 2606 quickly rises and pushes the needle plate 24.

[0068] The needle plate 24 drives the guide column 2610 and the perforated needle 25 to rise synchronously, the guide column 2610 drives the sealing plate 2611 to open the side flow port 2609, and the perforated needle 25 rises to unblock the hole 174 on the pollution isolation plate 173, the cleaned crystalline in the hole 174 flows to the lower side of the pollution isolation plate 173 along with the brine above the pollution isolation plate 173 through the side flow port 2609 on the pollution isolation plate 173, and the crystalline salt is discharged along with the high-concentration brine at the bottom of the kettle drum 2 to the outer pipe 2601.

[0069] The implementation principle of example 2 is: when the pipeline valve on the salt discharge pipe 19 is closed, at this time, the brine in the salt discharge pipe 19 cannot be discharged, and the liquid in the kettle drum 2 continues to increase, the floating ball 2603 drives the vertical rod 2602 to rise under the buoyancy of the liquid in the kettle drum 2, the vertical rod 2602 drives the arc rod 2606 to rotate and descend through the connecting rod 2607, the supporting block 2608 is away from the needle plate 24, and the conical surface of the limiting cone 2604 abuts against the edge of the outer pipe 2601, at this time, the outer pipe 2601 is blocked.

[0070] And the needle plate 24 under the action of gravity, the sparse hole needle 25 and pollution baffle 173 separation, the sealing plate 2611 at this time will be side flow port 2609 on the pollution baffle 173 blocked, until the liquid level sensor 172 is triggered, at this time, when the salt pipe 19 on the pipeline valve is opened, the pressure in the salt pipe 19 is reduced, and the liquid in the salt pipe 19 is discharged, the high pressure in the drum 2 makes the limit cone 2604 away from the edge of the outer tube 2601.

[0071] The high concentration of salt water in the bottom of the drum 2 will flow quickly from the outer tube 2601 to the salt pipe 19, the liquid level in the drum 2 drops quickly, and the salt water flowing out of the outer tube 2601 will impact the limit cone 2604 to drop, so that the vertical rod 2602 drops quickly, the vertical rod 2602 pushes the arc rod 2606 to rotate through the connecting rod 2607, the arc rod 2606 drives the scraper 27 to remove the crystalline salt on the bottom wall of the drum 2, the arc rod 2606 pushes the needle plate 24 quickly.

[0072] The needle plate 24 drives the guide column 2610 and the sparse hole needle 25 to rise synchronously, the guide column 2610 drives the sealing plate 2611 to open the side flow port 2609, the sparse hole needle 25 rises to unblock the hole 174 on the pollution baffle 173, the cleaned crystalline in the hole 174 will flow to the lower side of the pollution baffle 173 along with the salt water above the pollution baffle 173 through the side flow port 2609 on the pollution baffle 173, and the crystalline salt will flow to the outer tube 2601 along with the high concentration of salt water in the bottom of the drum 2 and be discharged.

[0073] The above are the preferred embodiments of the present application, not limited by the protection scope of the present application, therefore: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A large-capacity subcritical coal-fired CFB type oilfield steam injection boiler, comprising a steel frame (1), wherein a boiler drum (2), a furnace water-cooled wall (3), and a flue (4) are arranged on the steel frame (1), wherein an air distribution plate (5) and a secondary air device (6) are arranged on the furnace water-cooled wall (3), wherein a superheater (7), an upper economizer (8), an SCR device (9), a lower economizer (10), and an air preheater (11) are arranged sequentially on the flue (4), and a feeding device for conveying coal is provided at the bottom of the furnace water-cooled wall (3). The furnace water-cooled wall (3) is provided with an expansion joint (13) between its top outlet and the flue (4). A dust separator (14) for separating dust and air in the flue gas is provided between the flue (4) and the expansion joint (13). A return material device (15) is provided between the dust separator (14) and the furnace water-cooled wall (3). The return material device (15) is used to transport the dust separated by the dust separator (14) to the bottom of the furnace water-cooled wall (3). The steel frame (1) is provided with a softened water pipe (16) for transporting oilfield wastewater. The softened water pipe (16) is connected in sequence to the lower economizer (10), the upper economizer (8) and the bottom coil of the furnace water-cooled wall (3). The top coil of the furnace water-cooled wall (3) is connected to the boiler drum (2). The boiler drum (2) is provided with a separation component (17) for separating brine and steam. The top of the boiler drum (2) is connected to the superheater (7) with a steam pipe (18). The bottom of the boiler drum (2) is connected with a salt discharge pipe (19). A water spray desuperheater (20) is provided on the main steam outlet pipe of the superheater (7). The salt discharge pipe (19) is connected to the water spray desuperheater (20). The water spray desuperheater (20) is connected to the oil well through a pipe. A pressure measuring device for monitoring the pressure change inside the coil is provided on the coil of the furnace water-cooled wall (3).

2. The large-capacity subcritical coal-fired CFB type oilfield steam injection boiler according to claim 1, characterized in that: The pressure measuring device includes multiple pressure sensors (21) that are all mounted on the coils of the furnace water-cooled wall (3), and the pressure sensors (21) are electrically connected to the control system.

3. A large-capacity subcritical coal-fired CFB type oilfield steam injection boiler according to claim 1, characterized in that: The furnace water-cooled wall (3) includes a bottom water-cooled wall (31), a middle water-cooled wall (32), and an upper water-cooled wall (33). Disassembly plates (34) are provided between the middle water-cooled wall (32) and the bottom water-cooled wall (31), and between the middle water-cooled wall (32) and the upper water-cooled wall (33). Disassembly straight pipes (35) are connected between the coils on the middle water-cooled wall (32) and the coils on the bottom water-cooled wall (31), and between the coils on the middle water-cooled wall (32) and the coils on the upper water-cooled wall (33).

4. A large-capacity subcritical coal-fired CFB type oilfield steam injection boiler according to claim 1, characterized in that: The separation component (17) includes a steam-water separator (171) disposed inside the boiler drum (2). The coil on the furnace water-cooled wall (3) is connected to the inlet end of the steam-water separator (171). The outlet end of the steam-water separator (171) is located above the liquid level inside the boiler drum (2). A liquid level sensor (172) electrically connected to the control system is disposed on the boiler drum (2). A drain baffle (173) is disposed at the bottom inside the boiler drum (2). Several holes (174) are opened on the drain baffle (173). The drain valve at the bottom of the steam-water separator (171) is located below the drain baffle (173). The connection between the salt discharge pipe (19) and the boiler drum (2) is located below the drain baffle (173).

5. A large-capacity subcritical coal-fired CFB type oilfield steam injection boiler according to claim 4, characterized in that: A filter screen (22) is provided inside the boiler drum (2), and the filter screen (22) is located below the connection between the steam pipe (18) and the boiler drum (2).

6. A large-capacity subcritical coal-fired CFB type oilfield steam injection boiler according to claim 4, characterized in that: The pot cylinder (2) is placed horizontally. Multiple vertical guide posts (23) are evenly arranged around the pot cylinder (2). A needle plate (24) is slidably mounted on the multiple guide posts (23). Several vertical pore-removing needles (25) are arranged on the needle plate (24). The pore-removing needles (25) correspond one-to-one with the holes (174). The pore-removing needles (25) are used to insert into the holes (174). A dredging component (26) is provided on the pot cylinder (2) to drive the needle plate (24) to slide vertically back and forth.

7. A large-capacity subcritical coal-fired CFB type oilfield steam injection boiler according to claim 6, characterized in that: The unblocking component (26) includes an outer tube (2601) connected to the bottom of the inner drum (2), one end of the salt discharge pipe (19) is sleeved on the bottom end of the outer tube (2601), a vertical rod (2602) coaxial with the outer tube (2601) is vertically slidably arranged on the drain baffle (173), the top of the vertical rod (2602) is provided with an internally hollow float ball (2603), and the bottom of the vertical rod (2602) is provided with a limiting cone (2604). The diameter of the limiting cone (2604) gradually decreases along the direction from the upright (2602) to the float (2603). The conical surface of the limiting cone (2604) is used to abut the end edge of the outer tube (2601). An mounting plate (2605) is provided on the upright (2602) on the side of the drain baffle (173) facing away from the float (2603). An arc rod (2605) is provided on the inner side of the end of the boiler drum (2) and rotatably arranged along the axis of the boiler drum (2). 6) The center of the arc of the arc rod (2606) is located on the axis of the pot drum (2). The arc rod (2606) is symmetrically arranged about the axis of the upright rod (2602). A connecting rod (2607) is hinged between the mounting plate (2605) and the arc rod (2606). A support block (2608) is provided at the end of the arc rod (2606) away from the connecting rod (2607) and below the needle plate (24). The support block (2608) is used to abut against the... On the lower surface of the needle plate (24), a side outlet (2609) is provided on the drain baffle (173). A vertical guide post (2610) is provided on the needle plate (24). The guide post (2610) slides through the drain baffle (173). A sealing plate (2611) is provided on the guide post (2610) on the side of the drain baffle (173) facing away from the needle plate (24). The sealing plate (2611) is used to block the side outlet (2609).

8. A large-capacity subcritical coal-fired CFB type oilfield steam injection boiler according to claim 7, characterized in that: Multiple arc rods (2606) are evenly arranged along the axial direction of the pot drum (2). Multiple scraper rods (27) are provided together among the multiple arc rods (2606) on the side of the connecting rod (2607) facing away from the axis of the upright rod (2602). Multiple scraper rods (27) are evenly arranged on the arc rods (2606) circumferentially along the axis of the pot drum (2). The connecting rod (2607) is connected to one of the arc rods (2606). The scraper rods (27) are attached to the inner wall of the pot drum (2).

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