An apparatus for heat recovery from produced water in heavy oil thermal recovery and purification of boiler water

Abstract

The present invention provides a device for heat recovery of produced water in heavy oil thermal recovery and purification of boiler water, which includes a high-temperature flash tank, a boiler feed water pipeline, and a multi-stage evaporation device. A part of the secondary steam released after the produced water in heavy oil thermal recovery is flashed and cooled in the high-temperature flash tank enters the boiler feed water pipeline through a mixer, and the remaining part of the secondary steam serves as a heat source to enter the multi-stage evaporation device, evaporating and concentrating the purified soft water introduced into the multi-stage evaporation device. The condensed water generated by evaporation enters the boiler feed water pipeline. This device maximally recycles the waste heat of the produced water to the boiler system, and at the same time produces a corresponding amount of condensed water, realizing the treatment and purification of boiler water with lower energy consumption, recovering heat energy while providing qualified boiler water.

Description

Technical Field

[0001] The invention relates to a boiler water purification device, in particular to a device that utilizes the heat of water discharged from an oil field for purification. Background Art

[0002] At present, the effective utilization of heat energy in domestic heavy oil thermal recovery systems has always been the key to improving the quality and efficiency of heavy oil development. With the large-scale promotion and application of SAGD development, the contradiction between the maximum effective utilization of heat energy and the stable production of ground processes has become increasingly prominent, and has become a bottleneck restricting the large-scale adoption of SAGD technology development. In recent years, Fengcheng Oilfield technicians have done a lot of work to slow down the development of this contradiction, maintain the stable operation of ground production processes, and reduce environmental pressure. For example, high superheat steam injection, high-temperature membrane technology application, closed process modification, single well air cooling and heat dissipation test, etc. Among the above technologies, the fundamental purpose of superheated steam injection is to strengthen the utilization of heat energy from the steam injection link. Other technologies are only measures taken to maintain the normal operation of ground production processes. A systematic comprehensive utilization has not been formed. Summary of the invention

[0003] In order to overcome the problems in the prior art, the present invention provides a device for heat recovery and boiler water purification of produced water from heavy oil thermal recovery. The device can reuse the waste heat of produced water to the boiler system to the greatest extent, and produce a corresponding amount of condensed water at the same time, so as to achieve the purification of boiler water with lower energy consumption, recover heat energy and provide qualified boiler water at the same time.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A device for heat recovery of produced water from thermal recovery of heavy oil and purification of boiler water comprises a high-temperature flash tank, a boiler water inlet pipe and a multi-stage evaporation device, characterized in that the steam outlet of the high-temperature flash tank is respectively connected to the multi-stage evaporation device and the boiler water inlet pipe through pipes, wherein a blender is arranged at the place connected to the boiler water inlet pipe, a part of the secondary steam released through the steam outlet pipe after the produced water from thermal recovery of heavy oil passes through the high-temperature flash tank for flash evaporation and cooling enters the boiler water inlet pipe through the blender, the remaining part of the secondary steam enters the multi-stage evaporation device as a heat source, the purified softened water introduced into the multi-stage evaporation device is subjected to multi-stage evaporation and concentration, the secondary steam generated by each stage of evaporation enters the boiler water inlet pipe through the blender, and the condensed water generated by evaporation enters the boiler water inlet pipe.

[0006] The multi-stage evaporation device comprises a primary evaporation mechanism, a secondary evaporation mechanism, a three-stage first-effect evaporation mechanism, and a three-stage second-effect evaporation mechanism, and each stage of the evaporation mechanism comprises an evaporator and a flash tank.

[0007] The evaporator includes a cylinder body which has a hollow evaporation chamber. A heat exchange plate is arranged in the evaporation chamber. One end of the heat exchange plate has a heat source steam inlet, and the other end has a heat source steam outlet. A spray head is arranged above the heat exchange plate in the evaporation chamber. A steam outlet and a concentrated water outlet which are communicated with the evaporation chamber are respectively arranged above and below the cylinder body. A circulation pipe is connected between the concentrated water outlet and the spray head.

[0008] The circulation pipes at all levels are connected through a concentrated water pipeline. Among them, a water inlet is arranged on the circulation pipe of the first-stage evaporation mechanism, and the circulation pipe of the first-stage evaporation mechanism is connected with a purified softened water pipeline through the water inlet. A water outlet is also arranged on the circulation pipe of the three-stage and two-effect evaporation mechanism, and the circulation pipe of the three-stage and two-effect evaporation mechanism is connected with a concentrated water discharge pipe through the water outlet.

[0009] The steam outlets of the evaporators in each stage of evaporation mechanism are connected with the steam inlet of a flash tank through pipelines, and the steam outlet of the flash tank is connected with the heat source steam inlet of the next-stage evaporator.

[0010] The steam outlets of the flash tanks of the first-stage evaporation mechanism, the second-stage evaporation mechanism and the three-stage and two-effect evaporation mechanism are also connected with a boiler feed water pipeline through a mixer.

[0011] The steam outlet of the flash tank of the three-stage and two-effect evaporation mechanism is also connected with a condensate recovery device.

[0012] The liquid outlet of the flash tank of the three-stage and two-effect evaporation mechanism is connected with the boiler feed water pipeline through a pipeline.

[0013] Demineralized water is introduced into the boiler feed water pipeline, and the secondary steam entering the boiler feed water pipeline through the mixer heats the demineralized water.

[0014] It further includes a control mechanism. The control mechanism includes a controller, sensors and electric valves arranged in the multi-stage evaporation device. The controller automatically controls the opening and closing of the electric valves according to the sensor data.

[0015] The technical effects of the present invention are as follows:

[0016] The present invention uses a multi-stage flash evaporation technology of three-stage and two-effect for the heat recovery process of produced water in heavy oil thermal recovery, solves the problems of excessive heat energy loss and excessive impact of heat load on the ground process existing in current oilfield production, maximally recycles the waste heat of the produced water to the boiler system, and simultaneously produces a corresponding amount of condensate water, realizes treating and purifying boiler water with lower energy consumption, recovers heat energy and provides qualified boiler water at the same time. Thus, a set of new, low-consumption, high-efficiency and energy-saving comprehensive treatment process is provided. Description of the Drawings

[0017] The present invention will be further described below in conjunction with the drawings.

[0018] Figure 1 Schematic diagram of the overall structure of the device described in Embodiment 1 of the present invention;

[0019] Figure 2 Schematic diagram of the structure of the evaporator in Embodiment 1 of the present invention;

[0020] Figure 3 Schematic diagram of the control structure of the device described in Embodiment 1 of the present invention.

[0021] Wherein:

[0022] 1. High-temperature flash tank; 2. Primary evaporator; 3. Primary flash tank; 4. Secondary evaporator; 5. Secondary flash tank; 6. Tertiary first-effect evaporator; 7. Tertiary first-effect flash tank; 8. Tertiary second-effect evaporator; 9. Tertiary second-effect flash tank; 10. Primary circulation pump; 11. Secondary circulation pump; 12. Tertiary first-effect circulation pump; 13. Tertiary second-effect circulation pump; 14. Tertiary discharge pump; 15. Condensate external transfer pump; 16. Soft water supply pump; 17. Primary booster pump; 18. Secondary booster pump; 19. Tertiary booster pump; 20. Primary blender; 21. Secondary blender; 22. Tertiary blender; 23. Quaternary blender Detailed implementation manners Embodiment

[0023] As Figure 1 shown, a heavy oil thermal recovery produced water heat recovery and boiler water purification device includes a high-temperature flash tank 1, a boiler feed water pipeline, and a multi-stage evaporation device. The steam outlet of the high-temperature flash tank 1 is connected to the multi-stage evaporation device and the boiler feed water pipeline through pipelines respectively. A quaternary blender 23 is provided at the place connected to the boiler feed water pipeline. Part of the secondary steam released through the steam outlet pipeline after the heavy oil thermal recovery produced water is flashed and cooled in the high-temperature flash tank 1 enters the boiler feed water pipeline through the quaternary blender 23 to heat the demineralized water in the boiler feed water pipeline. The remaining part of the secondary steam serves as a heat source to enter the multi-stage evaporation device, and the purified soft water introduced into the multi-stage evaporation device is subjected to multi-stage evaporation and concentration. The secondary steam generated by each stage of evaporation enters the boiler feed water pipeline through a blender for heat energy recovery, and the condensate finally generated by evaporation is introduced into the boiler feed water pipeline as purified water.

[0024] The multi-stage evaporation device includes a primary evaporation mechanism, a secondary evaporation mechanism, a tertiary first-effect evaporation mechanism, and a tertiary second-effect evaporation mechanism. The primary evaporation mechanism includes a primary evaporator 2 and a primary flash tank 3; the secondary evaporation mechanism includes a secondary evaporator 4 and a secondary flash tank 5; the tertiary first-effect evaporation mechanism includes a tertiary first-effect evaporator 6 and a tertiary first-effect flash tank 7; the tertiary second-effect evaporation mechanism includes a tertiary second-effect evaporator 8 and a tertiary second-effect flash tank 9.

[0025] The specific structure of the evaporator is as Figure 2As shown, the evaporator includes a cylinder body, which has a hollow evaporation chamber. A heat exchange plate is arranged in the evaporation chamber. One end of the heat exchange plate has a heat source steam inlet, and the other end has a heat source steam outlet. A spray head is arranged above the heat exchange plate in the evaporation chamber. A steam outlet and a concentrated water outlet communicating with the evaporation chamber are respectively arranged above and below the cylinder body. A circulation pipe is connected between the concentrated water outlet and the spray head.

[0026] The circulation pipes at all levels are connected by a concentrated water pipeline. Among them, a water inlet is provided on the circulation pipe of the first-stage evaporation mechanism. The circulation pipe of the first-stage evaporation mechanism is connected to the purified softened water pipeline through the water inlet. A softened water supply pump 16 is arranged on the purified softened water pipeline. Purified softened water is pumped into the circulation pipe of the first-stage evaporation mechanism through the softened water supply pump 16. A water outlet is also provided on the circulation pipe of the three-stage double-effect evaporation mechanism. The circulation pipe of the three-stage double-effect evaporation mechanism is connected to the concentrated water discharge pipe through the water outlet. A three-stage discharge pump 14 is arranged on the concentrated water discharge pipe. The concentrated water concentrated by the multi-stage evaporation device is discharged from the concentrated water discharge pipe through the three-stage discharge pump 14 and is processed by the existing MVC system.

[0027] The steam outlets of the evaporators in each stage of the evaporation mechanism are connected to the steam inlet of the flash tank through pipelines. The steam outlet of the flash tank is connected to the heat source steam inlet of the next-stage evaporator.

[0028] The steam outlets of the flash tanks of the first-stage evaporation mechanism, the second-stage evaporation mechanism, and the three-stage double-effect evaporation mechanism are also connected to the boiler feed water pipeline through a mixer (three-stage mixer 22, second-stage mixer 21, and first-stage mixer 20).

[0029] The steam outlet of the flash tank of the three-stage double-effect evaporation mechanism is also connected to a condensation recovery device.

[0030] The liquid outlet of the flash tank of the three-stage double-effect evaporation mechanism is connected to the boiler feed water pipeline through a pipeline.

[0031] Demineralized water is introduced into the boiler feed water pipeline. The secondary steam entering the boiler feed water pipeline through the mixer heats the demineralized water.

[0032] It further includes a control mechanism. The control mechanism includes a controller, sensors and electric valves arranged in the multi-stage evaporation device. The controller automatically controls the opening and closing of the electric valves through the sensor data.

[0033] The specific working process of the above device is as follows: The high-temperature water obtained from the heavy oil thermal recovery enters the high-temperature flash tank 1. After the gas-liquid separation in the high-temperature water flash tank 1, secondary steam and low-temperature water are obtained. Among them, the low-temperature water is discharged, and after the pressure of the secondary steam is controlled, stable secondary steam is obtained.

[0034] A part of the stable secondary steam is mixed through the four-stage mixer 23 and then enters the boiler feed water pipeline to recover heat to heat the demineralized water in the boiler feed water pipeline for use in the boiler. The remaining part of the secondary steam enters the first-stage evaporator 2 as the heat source of the evaporator. In the first-stage evaporator 2, purified softened water is pumped in by the softened water feed pump 16. The purified softened water is sprayed from top to bottom in the first-stage evaporator 2. The steam generated after being heated by the heat exchange plate enters the first-stage flash tank 3 from the steam outlet at the upper end for gas-liquid separation to obtain the first-stage evaporation secondary steam. A part of the first-stage evaporation secondary steam enters the second-stage evaporator 4 as the heat source of the evaporator, and the remaining part of the first-stage evaporation secondary steam enters the boiler feed water pipe through the three-stage mixer 22 for heat energy recovery and utilization. The purified softened water obtains the first-stage concentrated water after the evaporation in the first-stage evaporator 2. The first-stage concentrated water enters the second-stage evaporator 4 through the first-stage circulation pump 10 for further concentration.

[0035] Similarly, the first-stage concentrated water is sprayed in the second-stage evaporator 4. The steam obtained after evaporation enters the second-stage flash tank 5 for gas-liquid separation to obtain the second-stage evaporation secondary steam. A part of the second-stage evaporation secondary steam enters the second-stage evaporator 4 as the heat source of the radiator, and the remaining part of the second-stage evaporation secondary steam is mixed through the three-stage mixer 22 and then enters the boiler water feed pipe for recovery and utilization. The first-stage concentrated water obtains the second-stage concentrated water after the evaporation in the second-stage evaporator 4. The second-stage concentrated water enters the third-stage single-effect evaporator 6 through the third-stage single-effect circulation pump 12 for further concentration.

[0036] The second-stage concentrated water is sprayed in the third-stage single-effect evaporator 6. The steam obtained after evaporation enters the third-stage single-effect flash tank 7 for gas-liquid separation to obtain the third-stage single-effect evaporation secondary steam. A part of the third-stage single-effect evaporation secondary steam enters the third-stage evaporation double-effect evaporator 8 as the heat source of the evaporator. The third-stage single-effect concentrated water obtained after the evaporation of the second-stage concentrated water in the third-stage single-effect evaporator 6. The third-stage single-effect concentrated water enters the third-stage double-effect evaporator 8 through the third-stage double-effect circulation pump 13 for further concentration.

[0037] The third-stage single-effect concentrated water is sprayed in the third-stage double-effect evaporator 8. The steam obtained after evaporation enters the third-stage double-effect flash tank 9 for gas-liquid separation to obtain the third-stage double-effect evaporation secondary steam. A part of the third-stage double-effect evaporation secondary steam is recovered by condensation, and the other part enters the boiler water feed pipe through the first-stage mixer 20 for recovery and utilization. The condensed water obtained after gas-liquid separation in the third-stage double-effect flash tank 9 is the salt-out condensed water, which is pumped into the boiler water feed pipe by the condensed water output pump 15 for use. The third-stage single-effect concentrated water generates the third-stage double-effect concentrated water under the evaporation in the third-stage double-effect evaporator 8. The third-stage double-effect concentrated water is discharged externally through the third-stage discharge pump 14.

[0038] To better achieve unattended operation of the above device, the present invention realizes automatic control of the device of the present invention through a control mechanism, and its control method is as follows Figure 3 as shown.

[0039] It includes the following control steps:

[0040] 1. Feed control

[0041] According to the display of the flowmeter after the feed pump, automatically adjust the flow rate to ensure stable feed quantity.

[0042] According to the display of the flowmeter after the first-stage booster pump 17, automatically adjust the flow rate to control the amount of demineralized water for blending.

[0043] 2. Liquid level control

[0044] Based on the data of the low-temperature water level sensor after flashing in the high-temperature water flash evaporation tank 1, control the opening degree of the electric valve for low-temperature water discharge;

[0045] Based on the data of the liquid level sensor of the liquid in the first-stage evaporator 2, control the opening degree of the first-stage discharge electric valve;

[0046] Based on the data of the liquid level sensor of the liquid in the second-stage evaporator 4, control the opening degree of the second-stage discharge electric valve;

[0047] Based on the data of the liquid level sensor of the liquid in the third-stage first-effect evaporator 6, control the opening degree of the third-stage first-effect discharge electric valve;

[0048] Based on the data of the liquid level sensor of the liquid in the third-stage second-effect evaporator 8, control the opening degree of the concentrated water discharge electric valve;

[0049] Based on the data of the condensate water level sensor in the third-stage second-effect flash evaporation tank 9, control the opening degree of the condensate water discharge electric valve;

[0050] 3. Control of the mixing amount of secondary steam at each stage

[0051] Based on the data of the pressure sensor after the first-stage mixer 20, control the opening degree of the incoming liquid electric valve; at the same time, based on the data of the temperature sensor after the first-stage mixer, control the opening degree of the secondary steam electric valve to control the steam mixing amount;

[0052] Based on the data of the temperature sensor after the second-stage mixer 21, control the opening degree of the secondary steam electric valve to control the steam mixing amount; at the same time, based on the pressure after the second-stage mixer 21, control the opening degree of the valve after the second-stage booster pump 18 to control the feed pressure of the next-stage mixer;

[0053] Based on the data of the temperature sensor after the third-stage mixer 22, control the opening degree of the secondary steam electric valve to control the steam mixing amount; at the same time, based on the pressure after the second-stage mixer 22, control the opening degree of the valve after the second-stage booster pump 19 to control the feed pressure of the next-stage mixer;

[0054] Control the opening degree of the secondary steam electric valve to control the steam blending amount based on the temperature sensor data after passing through the four-stage blender 23;

[0055] Those skilled in the art will recognize that various modifications, changes, and combinations can be made to the above embodiments without departing from the scope of the present invention, and such modifications, changes, and combinations are considered to be within the scope of the original creative idea.

Claims

1. A heat recovery device for produced water in heavy oil thermal recovery and a boiler water purification device, comprising a high-temperature flash tank, a boiler feed water pipeline, and a multi-stage evaporation device. Characterized in that, The steam outlet of the high-temperature flash tank is connected to the multi-stage evaporation device and the boiler feed water pipeline respectively through pipelines. A four-stage mixer is provided at the place connected to the boiler feed water pipeline. Part of the secondary steam released through the steam outlet pipeline after the heavy oil thermal recovery produced water is flash-cooled in the high-temperature flash tank enters the boiler feed water pipeline through the four-stage mixer. The remaining part of the secondary steam serves as a heat source to enter the multi-stage evaporation device, and the purified softened water introduced into the multi-stage evaporation device is subjected to multi-stage evaporation and concentration. The secondary steam generated by the evaporation of the first-stage evaporation mechanism, the second-stage evaporation mechanism, and the third-stage double-effect evaporation mechanism enters the boiler feed water pipeline through the first-stage mixer, the second-stage mixer, and the third-stage mixer respectively. The condensed water generated by evaporation enters the boiler feed water pipeline. The first-stage evaporation mechanism includes a liquid level sensor for the liquid; the multi-stage evaporation device includes a first-stage evaporation mechanism, a second-stage evaporation mechanism, a third-stage single-effect evaporation mechanism, and a third-stage double-effect evaporation mechanism. Each stage of the evaporation mechanism includes an evaporator and a flash tank; the evaporator includes a cylinder body, the cylinder body has a hollow evaporation chamber, a heat exchange plate is arranged in the evaporation chamber, one end of the heat exchange plate has a heat source steam inlet, and the other end has a heat source steam outlet. A spray head is arranged above the heat exchange plate in the evaporation chamber. A steam outlet and a concentrated water outlet communicated with the evaporation chamber are respectively arranged above and below the cylinder body. A circulation pipe is connected between the concentrated water outlet and the spray head.

2. A heat recovery device for produced water in heavy oil thermal recovery and a boiler water purification device according to claim 1, Characterized in that, The circulation pipes at all levels are connected through a concentrated water pipeline. Among them, the circulation pipe of the first-stage evaporation mechanism has a water inlet, and the circulation pipe of the first-stage evaporation mechanism is connected to the purified softened water pipeline through the water inlet. The circulation pipe of the third-stage double-effect evaporation mechanism is also provided with a water outlet, and the circulation pipe of the third-stage double-effect evaporation mechanism is connected to the concentrated water discharge pipe through the water outlet.

3. A heat recovery device for produced water in heavy oil thermal recovery and a boiler water purification device according to claim 2, Characterized in that, The steam outlet of the evaporator in each stage of the evaporation mechanism is connected to the steam inlet of the flash tank through a pipeline, and the steam outlet of the flash tank is connected to the heat source steam inlet of the next-stage evaporator.

4. A heat recovery device for produced water in heavy oil thermal recovery and a boiler water purification device according to claim 3, Characterized in that, The steam outlets of the flash tanks of the first-stage evaporation mechanism, the second-stage evaporation mechanism, and the third-stage double-effect evaporation mechanism are connected to the boiler feed water pipeline through the first-stage mixer, the second-stage mixer, and the third-stage mixer respectively.

5. A heat recovery device for produced water in heavy oil thermal recovery and a boiler water purification device according to claim 4, Characterized in that, The steam outlet of the flash tank of the third-stage double-effect evaporation mechanism is also connected to a condensate recovery device.

6. A heat recovery device for produced water in heavy oil thermal recovery and a boiler water purification device according to claim 5, Characterized in that, The liquid outlet of the flash tank of the third-stage double-effect evaporation mechanism is connected to the boiler feed water pipeline through a pipeline.

7. A heat recovery device for produced water in heavy oil thermal recovery and a boiler water purification device as described in claim 6, characterized in that, demineralized water is introduced into the boiler feed water pipeline, and the secondary steam entering the boiler feed water pipeline through the first-stage mixer, the second-stage mixer or the third-stage mixer heats the demineralized water.

8. A heat recovery device for produced water in heavy oil thermal recovery and a boiler water purification device as described in any one of claims 1-7, characterized in that, it further includes a control mechanism, and the control mechanism includes a controller, sensors and electric valves arranged in the multi-stage evaporation device, and the controller automatically controls the opening and closing of the electric valves through the sensor data.

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