Oil field steam-injection boiler discharge system and use method

Abstract

The invention provides an oil field steam-injection boiler discharge system and a use method, and relates to the technical field of oil mine exploitation, the oil field steam-injection boiler discharge system comprises a boiler, a carbon dioxide introduction device, an oxygen introduction device, a mixer and a flue gas treatment device; the boiler comprises a combustor, a chimney and a ventilation pipeline connected between the combustor and the chimney. The carbon dioxide feeding device and the oxygen feeding device are connected to the mixer in parallel, and the combustor is connected with the mixer. The chimney is connected with the flue gas treatment device, the flue gas treatment device comprises a flue gas condenser and a flue gas water segregator, a hot flue gas inlet of the flue gas condenser is connected with the chimney, and the flue gas water segregator is connected with the carbon dioxide introducing device; and the flue gas condenser is connected in series between the combustor and the mixer. According to the invention, boiler flue gas can be recycled, nitrogen in air is isolated, and generation of nitrogen oxides is avoided; carbon dioxide can be recycled; and oil field steam-injection boiler emission is realized.

Description

Technical Field

[0001] The invention relates to the technical field of oil mining, and in particular to an oil field steam injection boiler exhaust system and a use method thereof. Background Art

[0002] Heavy oil heat uses oilfield steam injection boilers with natural gas (oil) as fuel. Natural gas (oil) is mixed with air and burned in the burner, producing high-concentration nitrogen oxides and low-concentration carbon dioxide in the combustion products. With the improvement of social awareness of environmental protection and the implementation of the dual-carbon strategy, the requirements for nitrogen oxide emissions in flue gas are becoming more and more stringent.

[0003] However, the treatment of high-concentration nitrogen oxides and the recovery of low-concentration carbon dioxide are technically difficult and costly. High-concentration NOx is usually composed of a variety of nitrogen oxides, including NO and NO2. Different nitrogen oxides have different reactivity and treatment methods, which are cumbersome to operate and costly. Currently, commonly used CO2 separation technologies include adsorption, membrane separation, solvent absorption, etc. Among them, the adsorption method has limitations such as limited adsorbent capacity and low selectivity. The CO2 produced by the membrane separation method is of low purity and the membrane material has poor durability. The solvent adsorption method has high absorbent regeneration heat consumption, large absorbent loss, high operating cost and large equipment investment. It is not suitable for steam injection boiler sites and is difficult to meet emission requirements.

[0004] The patent with announcement number CN204962699U discloses a combined flue gas condensing device for oilfield steam injection boilers, which can use flue gas preheating to heat the water inlet of the steam injection boiler and recycle the water vapor in the flue gas, reducing thermal pollution and water resource waste, and reducing carbon emissions. However, without carbon recovery, the carbon emissions are still large; in addition, the problem of generating a large amount of nitrogen oxides has not been solved. Summary of the invention

[0005] The object of the present invention is to provide an oilfield steam injection boiler emission system and a use method, which can achieve low nitrogen and low carbon emissions of the oilfield steam injection boiler, has a simple structure and low cost.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] An oilfield steam injection boiler exhaust system comprises a boiler, a carbon dioxide introduction device, an oxygen introduction device, a mixer and a flue gas treatment device;

[0008] The boiler comprises a burner, a chimney, and an air duct connected between the burner and the chimney;

[0009] The chimney is connected to a flue gas treatment device, the flue gas treatment device includes a flue gas condenser and a flue gas water separator, and the hot flue gas inlet of the flue gas condenser is connected to the chimney;

[0010] The carbon dioxide introduction device and the oxygen introduction device are connected in parallel to the mixer, a blower is also connected in series between the burner and the mixer, the flue gas condenser is connected in series between the burner and the blower, the mixer is connected to the cold medium inlet of the flue gas condenser; the flue gas water separator is connected to the carbon dioxide introduction device.

[0011] Furthermore: the carbon dioxide introduction device includes a buffer tank 1 and a ventilation pipeline connected between the mixer and the buffer tank 1, and the buffer tank 1 is also connected to the flue gas water separator.

[0012] Furthermore, the buffer tank is connected to a water bath vaporizer, and the water bath vaporizer is also connected to a liquid carbon dioxide inlet pipeline.

[0013] Furthermore: the oxygen introduction device includes a buffer tank 2 and a ventilation pipeline connected between the mixer and the buffer tank 2, and the buffer tank 2 is also connected to the liquid oxygen inlet pipeline.

[0014] Furthermore: a second water bath vaporizer is connected between the second buffer tank and the liquid oxygen inlet pipeline.

[0015] Furthermore: the flue gas treatment device also includes a water preheater connected in series between the flue gas condenser and the flue gas water separator, and the water preheater is also connected to a water circulation pipeline, and the water circulation pipeline passes through the boiler.

[0016] Furthermore: it also includes a cooling tower connected in series to the water circulation pipeline, and the cooling tower is also connected to cooling water.

[0017] Furthermore: a three-way regulating valve is installed on the chimney, and the flue gas treatment device is connected to one of the outlets of the three-way regulating valve.

[0018] The present invention also provides a method for using an oilfield steam injection boiler exhaust system, comprising the following steps:

[0019] S1: Turn on the burner and blower. The blower introduces air into the burner to assist combustion, and the boiler starts to run.

[0020] S2: Turn on the carbon dioxide introduction device and the oxygen introduction device, and introduce carbon dioxide and oxygen into the mixer for mixing until a predetermined mixed concentration is reached;

[0021] S3: When the boiler is running stably, the blower sends the carbon dioxide-oxygen mixed gas in the mixer into the flue gas condenser. At the same time, the flue gas discharged from the chimney enters the flue gas condenser and exchanges heat with the carbon dioxide-oxygen mixed gas in the flue gas condenser. The flue gas cooled by heat exchange enters the flue gas water separator. The flue gas carbon dioxide-oxygen mixed gas heated by heat exchange continues to be passed into the burner for combustion.

[0022] S4: After the flue gas water separator separates the flue gas and water, the flue gas is discharged into the carbon dioxide inlet device.

[0023] Furthermore: S3 also includes: the high-temperature flue gas passes through a water preheater before entering the flue gas water separator to heat circulating water, and the circulating water passes through a water circulation pipeline into the boiler to heat boiler water.

[0024] Compared with the original technology, the present invention has the following beneficial effects:

[0025] 1. The present invention isolates nitrogen in the air and avoids the generation of nitrogen oxides by recycling boiler flue gas.

[0026] 2. In the present invention, the flue gas is recycled and utilized through the flue gas water separator. After the flue gas is processed by the flue gas water separator, the carbon dioxide in the flue gas can be recycled and utilized.

[0027] 3. Flue gas mainly contains carbon dioxide and water, and the content of other impurities is relatively small. After the flue gas water separator separates the water, the concentration of carbon dioxide in the flue gas increases. After the concentration of carbon dioxide increases, it can be recycled. It only needs to be compressed and purified. The process is simple and the cost of carbon dioxide recovery is reduced.

[0028] Fourth, the heat of the flue gas in the present invention is recycled by the flue gas condenser to heat the burning carbon dioxide-oxygen mixed gas, thereby saving energy, being low-carbon and environmentally friendly.

[0029] 5. In the present invention, the heat of the flue gas is further recovered by the water preheater, and the heat is re-invested in the boiler or water bath evaporator through circulating water, thereby saving energy, being low-carbon and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of Example 1;

[0031] Figure 2 It is a structural schematic diagram of Example 2;

[0032] Figure 3 It is a structural schematic diagram of Example 3;

[0033] Figure 4 It is an enlarged structural schematic diagram of the pressure reducing pipeline;

[0034] Figure 5 This is an enlarged structural diagram of the pressure regulating pipeline.

[0035] In the figure: 1. Boiler; 1.1. Burner; 1.2. Chimney; 1.3. Three-way regulating valve; 2. Carbon dioxide introduction device; 2.1. Buffer tank 1; 2.2. Water bath vaporizer 1; 3. Oxygen introduction device; 3.1. Buffer tank 2; 3.2. Water bath vaporizer 2; 4. Mixer; 5. Flue gas treatment device; 5.1. Flue gas condenser; 5.2. Flue gas water separator; 5.21. Drain valve; 5.22. Carbon dioxide Capture device; 5.23, flue gas booster fan; 5.24, flue gas electric shut-off valve; 5.3, water preheater; 6, blower; 7, cooling tower; 8, pressure reducing pipeline; 8.1, flow meter; 8.2, pressure reducing valve; 8.3, main line shut-off valve; 8.4, bypass shut-off valve; 8.5, carbon dioxide shut-off valve; 9, pressure regulating pipeline; 9.1, pressure measuring point; 9.2, pressure regulating valve; 9.3, temperature measuring point; 9.4, safety valve. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0038] Example 1

[0039] like Figure 1 As shown: an oilfield steam injection boiler exhaust system, including a boiler 1, a carbon dioxide introduction device 2, an oxygen introduction device 3, a mixer 4 and a flue gas treatment device 5; the boiler 1 includes a burner 1.1, a chimney 1.2 and a ventilation pipe connected between the burner 1.1 and the chimney 1.2; a three-way regulating valve 1.3 is installed on the chimney 1.2, and the flue gas treatment device 5 is connected to one of the outlets of the three-way regulating valve 1.3. The carbon dioxide introduction device 2 and the oxygen introduction device 3 are connected in parallel to the mixer 4, the burner 1.1 is connected to the mixer 4, and a blower 6 is also connected in series between the burner 1.1 and the mixer 4.

[0040] The carbon dioxide introduction device 2 includes a buffer tank 2.1 and a carbon dioxide shut-off valve 8.5 connected between the mixer 4 and the buffer tank 2.1; the buffer tank 2.1 is also connected to the flue gas water separator 5.2, and a flue gas booster fan 5.23 and a flue gas electric shut-off valve 5.24 are installed between the buffer tank 2.1 and the flue gas water separator 5.2; a carbon dioxide capture device 5.22 is also connected between the flue gas water separator 5.2 and the buffer tank 2.1 through a three-way regulating valve 1.3.

[0041] The oxygen introduction device 3 comprises a buffer tank 2 3.1 and a pressure reducing pipeline 8 connected between the mixer 4 and the buffer tank 2 3.1; the buffer tank 2 3.1 is also connected to the liquid oxygen inlet pipeline via a pressure regulating pipeline 9.

[0042] The pressure reducing pipeline 8 is sequentially installed with a flow meter 8.1, a pressure reducing valve 8.2, and a main line cut-off valve 8.3. The pressure reducing pipeline 8 also includes a bypass cut-off valve 8.4 connected in parallel with the flow meter 8.1, the pressure reducing valve 8.2, and the main line cut-off valve 8.3. The pressure regulating pipeline 9 is installed with a pressure measuring point 9.1, a pressure regulating valve 9.2, a temperature measuring point 9.3, and a safety valve 9.3.

[0043] The chimney 1.2 is connected to the flue gas treatment device 5, and the flue gas treatment device 5 includes a flue gas condenser 5.1 and a flue gas water separator 5.2. The hot flue gas inlet of the flue gas condenser 5.1 is connected to the chimney 1.2, and the flue gas water separator 5.2 is connected to the carbon dioxide introduction device 2; the flue gas condenser 5.1 is connected in series between the burner 1.1 and the mixer 4, and the mixer 4 is connected to the cold medium inlet of the flue gas condenser 5.1; the flue gas treatment device 5 also includes a water preheater 5.3 connected in series between the flue gas condenser 5.1 and the flue gas water separator 5.2, and the water preheater 5.3 is also connected to a water circulation pipeline, which passes through the boiler 1, and the boiler 1 feed water pump is installed on the water circulation pipeline to supply water to the boiler 1.

[0044] The specific working principle of this embodiment is as follows:

[0045] High-temperature flue gas is discharged from the oil field steam injection boiler 1 and enters the high-temperature flue gas three-way regulating valve 1.3 to switch the flue gas process. When the system is operating normally, the flue gas enters the flue gas condenser 5.1 through the flue to recover the flue gas waste heat and condense the water vapor in the flue gas. The condensed low-temperature flue gas enters the water preheater 5.3 for deep cooling and condensation. After condensation, the mixture of flue gas and water enters the flue gas water separator 5.2 to separate the flue gas and water. The water content in the separated flue gas is reduced to less than 4%. The separated water is discharged through the flue gas water separator 5.2 drain valve 5.21 and pipeline. The separated flue gas is adjusted by the low-temperature flue gas three-way regulating valve 5.2. The valve is used to adjust the flue gas flow rate. A part of the flue gas enters the carbon dioxide capture device 5.22; a part of the flue gas is pressurized by the flue gas booster fan 5.23 and then enters the buffer tank 2.1 through the flue gas electric shut-off valve 5.24. The flue gas is measured by the flow meter 8.1 and the carbon dioxide shut-off valve 8.5 in turn, and mixed with oxygen in the mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through the blower 6 and is preheated in the flue gas condenser 5.1, and finally enters the burner 1.1 for combustion. The high-temperature flue gas releases heat in the oil field steam injection boiler 1, and the heat is recovered by the oil field steam injection boiler 1 to produce high-temperature and high-pressure steam. In the case of system shutdown for maintenance, initial operation or emergency, the high-temperature flue gas is discharged from the chimney 1.2; or the low-temperature flue gas is discharged through the low-temperature flue gas three-way regulating valve.

[0046] Oxygen passes through its inlet pipeline, is decompressed by the pressure reducing valve 8.2, and enters the buffer tank 3.1. The gas is measured by the flow meter 8.1 in turn. If two-level pressure reduction is required, it passes through the oxygen pressure reducing valve 8.2 and the main line cut-off valve 8.3, and is mixed with oxygen in the mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through the blower 6, is preheated in the flue gas condenser 5.1, and finally enters the burner 1.1 for combustion. The high-temperature flue gas releases heat in the oil field steam injection boiler 1, and the heat is recovered by the oil field steam injection boiler 1 to produce high-temperature and high-pressure steam.

[0047] If secondary pressure reduction is not required, oxygen passes through oxygen bypass cut-off valve 8.4 and is mixed with carbon dioxide in mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through blower 6 and is preheated in flue gas condenser 5.1. Finally, it enters burner 1.1 for combustion. The high-temperature flue gas releases heat in oilfield steam injection boiler 1, and the heat is recovered by oilfield steam injection boiler 1 to produce high-temperature and high-pressure steam.

[0048] The boiler 1 feed water enters the water preheater 5.3 through the feed water pipeline, absorbs the heat of the flue gas, and the temperature rises. After entering the boiler 1 feed water pump, it enters the oil field steam injection boiler 1.

[0049] Example 2

[0050] like Figure 2 As shown, the difference between this embodiment and embodiment 1 is that:

[0051] A water bath vaporizer 2 3.2 is installed between the buffer tank 2 3.1 and the liquid oxygen inlet pipeline, and the water bath vaporizer 2 and the buffer tank 2 3.1 are connected via a pressure regulating pipeline 9.

[0052] The flue gas treatment device 5 also includes a water preheater 5.3 connected in series between the flue gas condenser 5.1 and the flue gas water separator 5.2. The water preheater 5.3 is also connected to a water circulation pipeline, which passes through the boiler 1 and the water bath gasifier 2 3.2. The water circulation pipeline is equipped with a boiler 1 feed water pump to supply water to the boiler 1.

[0053] The specific working principle of this implementation is as follows:

[0054] Liquid (low temperature) oxygen enters the water bath vaporizer 2 3.2 through its inlet pipeline for absorption and vaporization, is reduced in pressure by the pressure reducing valve 8.2, and enters the buffer tank. The gas is measured by the flow meter 8.1, the pressure reducing valve 8.2 and the main line shut-off valve 8.3 in turn, and is mixed with carbon dioxide in the mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through the blower 6, is preheated in the flue gas condenser 5.1, and finally enters the burner 1.1 for combustion. The high-temperature flue gas releases heat in the oil field steam injection boiler 1, and the heat is recovered by the oil field steam injection boiler 1 to produce high-temperature and high-pressure steam.

[0055] If secondary pressure reduction is not required, oxygen passes through oxygen bypass cut-off valve 8.4 and is mixed with carbon dioxide in mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through blower 6 and is preheated in flue gas condenser 5.1. Finally, it enters burner 1.1 for combustion. The high-temperature flue gas releases heat in oilfield steam injection boiler 1, and the heat is recovered by oilfield steam injection boiler 1 to produce high-temperature and high-pressure steam.

[0056] The high-temperature flue gas is discharged from the oil field steam injection boiler 1 and enters the high-temperature flue gas three-way regulating valve 1.3 to switch the flue gas process. When the system is operating normally, the flue gas enters the flue gas condenser 5.1 through the flue to recover the flue gas waste heat and condense the water vapor in the flue gas. The condensed low-temperature flue gas enters the water preheater 5.3 for deep cooling and condensation. After condensation, the mixture of flue gas and water enters the flue gas water separator 5.2 to separate the flue gas and water. The water content in the separated flue gas is reduced to less than 4%. The separated water is discharged through the flue gas water separator 5.2 drain valve 5.21 and pipeline. The separated flue gas is The three-way regulating valve is used to regulate the flue gas flow rate. A part of the flue gas enters the carbon dioxide capture device 5.22; a part of the flue gas is pressurized by the flue gas booster fan and enters the buffer tank 2.1 through the flue gas electric shut-off valve. The flue gas is measured by the flow meter 8.1 and the carbon dioxide shut-off valve 8.5 in turn, and mixed with oxygen in the mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through the blower 6 and is preheated in the flue gas condenser 5.1, and finally enters the burner 1.1 for combustion. The high-temperature flue gas releases heat in the oil field steam injection boiler 1, and the heat is recovered by the oil field steam injection boiler 1 to produce high-temperature and high-pressure steam. In the event of system shutdown for maintenance, initial operation or emergency, the high-temperature flue gas is discharged from the chimney 1.2; or the low-temperature flue gas is discharged through the low-temperature flue gas three-way regulating valve.

[0057] The boiler 1 feed water enters the water preheater 5.3 through the feed water pipeline, absorbs the heat of the flue gas, increases the temperature, enters the water bath gasifier 2 3.2, gasifies the oxygen, enters the boiler 1 feed water pump, and then enters the oil field steam injection boiler 1.

[0058] Example 3

[0059] As attached Figure 3 As shown, the difference between this embodiment and embodiment 1 is that:

[0060] The carbon dioxide introduction device 2 includes a buffer tank 2.1 and a pressure reducing pipeline 8 connected between the mixer 4 and the buffer tank 2.1; the buffer tank 2.1 is also connected to the flue gas water separator 5.2, and a flue gas booster fan and a flue gas electric shut-off valve are installed between the buffer tank 2.1 and the flue gas water separator 5.2; the flue gas water separator 5.2 and the buffer tank 2.1 are also connected to a carbon dioxide capture device 5.22 through a three-way regulating valve 1.3; the buffer tank 2.1 is connected to the water bath vaporizer 2.2 through a pressure regulating pipeline 9, and the water bath vaporizer 2.2 is also connected to a liquid carbon dioxide inlet pipeline.

[0061] A water bath vaporizer 2 3.2 is installed between the buffer tank 2 3.1 and the liquid oxygen inlet pipeline, and the water bath vaporizer 2 and the buffer tank 2 3.1 are connected via a pressure regulating pipeline 9.

[0062] The flue gas treatment device 5 also includes a water preheater 5.3 connected in series between the flue gas condenser 5.1 and the flue gas water separator 5.2. The water preheater 5.3 is also connected to a water circulation pipeline, which includes a water bath vaporizer 1 2.2 and a water bath vaporizer 2 3.2. A cooling tower 7 is connected in series to the water circulation pipeline, and the cooling tower 7 is also connected to cooling water.

[0063] The specific working principle of this implementation is as follows:

[0064] Liquid carbon dioxide enters the water bath vaporizer 2.2 through its inlet pipeline for absorption and vaporization, is decompressed by the pressure reducing valve 8.2, and enters the buffer tank 2.1. The gas passes through the flow meter 8.1 for flow measurement, the pressure reducing valve 8.2 and the main line shut-off valve 8.3 in turn, and is mixed with oxygen in the mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through the blower 6, is preheated in the flue gas condenser 5.1, and finally enters the burner 1.1 for combustion.

[0065] Liquid (low temperature) oxygen enters the water bath vaporizer 2 3.2 through its inlet pipeline for heat absorption and vaporization, is reduced in pressure by the pressure reducing valve 8.2, and enters the buffer tank. The gas is measured by the flow meter 8.1, the pressure reducing valve 8.2 and the main line shut-off valve 8.3 in turn, and is mixed with oxygen in the mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through the blower 6, is preheated in the flue gas condenser 5.1, and finally enters the burner 1.1 for combustion. The high-temperature flue gas releases heat in the oil field steam injection boiler 1, and the heat is recovered by the oil field steam injection boiler 1 to produce high-temperature and high-pressure steam.

[0066] If secondary pressure reduction is not required, oxygen passes through oxygen bypass cut-off valve 8.4 and is mixed with carbon dioxide in mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through blower 6 and is preheated in flue gas condenser 5.1. Finally, it enters burner 1.1 for combustion. The high-temperature flue gas releases heat in oilfield steam injection boiler 1, and the heat is recovered by oilfield steam injection boiler 1 to produce high-temperature and high-pressure steam.

[0067] The high-temperature flue gas is discharged from the oil field steam injection boiler 1 and enters the high-temperature flue gas three-way regulating valve 1.3 to switch the flue gas process. When the system is operating normally, the flue gas enters the flue gas condenser 5.1 through the flue to recover the flue gas waste heat and condense the water vapor in the flue gas. The condensed low-temperature flue gas enters the water preheater 5.3 for deep cooling and condensation. After condensation, the mixture of flue gas and water enters the flue gas water separator 5.2 to separate the flue gas and water. The separated water is discharged through the flue gas water separator 5.2 drain valve 5.21 and pipeline. The water content in the separated flue gas is reduced to less than 4%. The regulating valve is used to regulate the flue gas flow. A part of the flue gas enters the carbon dioxide capture device 5.22; a part of the flue gas is pressurized by the flue gas booster fan and enters the buffer tank 2.1 through the flue gas electric shut-off valve. The flue gas is measured by the flow meter 8.1 and the main line shut-off valve 8.3 in turn. It is mixed with oxygen in the mixer 4 to reach a predetermined mixed concentration. The mixed gas passes through the blower 6 and is preheated in the flue gas condenser 5.1. Finally, it enters the burner 1.1 for combustion. The high-temperature flue gas releases heat in the oil field steam injection boiler 1, and the heat is recovered by the oil field steam injection boiler 1 to produce high-temperature and high-pressure steam. In the case of system shutdown for maintenance, initial operation or emergency, the high-temperature flue gas is discharged from the chimney 1.2; or the low-temperature flue gas is discharged through the low-temperature flue gas three-way regulating valve.

[0068] The cooling water enters the cooling tower 7 through the cooling tower 7 water supply pipeline, enters the water preheater 5.3 through the circulating water pump to exchange heat with the flue gas, the cooling water temperature rises, and enters the water bath vaporizer 1 2.2 and the water bath vaporizer 2 3.2 through the return water pipeline to heat the carbon dioxide and oxygen therein, and enters the cooling tower 7 after the cooling water temperature decreases. If the water temperature is too high, the cooling tower 7 is started to cool down. The cooled circulating water is input into the water preheater 5.3 to cool the flue gas, so that the water vapor in the flue gas is quickly condensed, which is convenient for separating the water in the flue gas water separator.

[0069] Embodiment 4:

[0070] This embodiment provides a method for using any one of the above-mentioned discharge systems in embodiments 1-3 above:

[0071] S1: Turn on the burner 1.1 and the blower 6. The blower 6 introduces air into the burner 1.1 to assist combustion, and the boiler 1 starts to operate;

[0072] S2: Open the carbon dioxide introduction device 2 and the oxygen introduction device 3, and introduce carbon dioxide and oxygen into the mixer 4 for mixing until a predetermined mixed concentration is reached;

[0073] S3: When the boiler 1 is running stably, the blower 6 gradually introduces the carbon dioxide-oxygen mixed gas in the mixer 4 to replace the air, and the carbon dioxide-oxygen mixed gas passes through the flue gas condenser 5.1; at the same time, the high-temperature flue gas is discharged from the chimney 1.2, passes through the flue gas condenser 5.1, and exchanges heat with the carbon dioxide-oxygen mixed gas in the flue gas condenser 5.1; the flue gas carbon dioxide-oxygen mixed gas after heat exchange and temperature increase continues to be introduced into the burner 1.1 for combustion; the high-temperature flue gas after heat exchange and temperature reduction is introduced into the water preheater 5.3 to heat the circulating water, and the circulating water is introduced into the boiler 1 through the water circulation pipeline to heat the boiler 1 water; finally, the flue gas after heat exchange and temperature reduction again through the water preheater enters the flue gas water separator 5.2.

[0074] S4: After the flue gas and water are separated by the flue gas water separator 5.2, the flue gas is discharged into the carbon dioxide introduction device 2.

[0075] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. An oilfield steam injection boiler discharge system, characterized in that: It includes a boiler, a carbon dioxide introduction device, an oxygen introduction device, a mixer and a flue gas treatment device; The boiler comprises a burner, a chimney, and an air duct connected between the burner and the chimney; The chimney is connected to a flue gas treatment device, the flue gas treatment device includes a flue gas condenser and a flue gas water separator, and the hot flue gas inlet of the flue gas condenser is connected to the chimney; The carbon dioxide introduction device and the oxygen introduction device are connected in parallel to the mixer, a blower is also connected in series between the burner and the mixer, the flue gas condenser is connected in series between the burner and the blower, the mixer is connected to the cold medium inlet of the flue gas condenser; the flue gas water separator is connected to the carbon dioxide introduction device.

2. The oilfield steam injection boiler exhaust system according to claim 1, characterized in that: The carbon dioxide introduction device comprises a buffer tank 1, the outlet of the buffer tank 1 is connected to the mixer, and the inlet of the buffer tank 1 is connected to the flue gas water separator.

3. The oilfield steam injection boiler exhaust system according to claim 2, characterized in that: The inlet of the buffer tank 1 is connected to the water bath vaporizer 1, and the inlet of the water bath vaporizer 1 is also connected to the liquid carbon dioxide inlet pipeline.

4. The oilfield steam injection boiler exhaust system according to claim 1, characterized in that: The oxygen introduction device comprises a buffer tank 2, the outlet of the buffer tank 2 is connected to the mixer, and the inlet of the buffer tank 2 is also connected to the liquid oxygen inlet pipeline.

5. The oilfield steam injection boiler exhaust system according to claim 4, characterized in that: A second water bath vaporizer is also connected between the second buffer tank and the liquid oxygen inlet pipeline.

6. The oilfield steam injection boiler exhaust system according to claim 1, characterized in that: The flue gas treatment device also includes a water preheater connected in series between the flue gas condenser and the flue gas water separator. The water preheater is also connected to a water circulation pipeline, and the water circulation pipeline passes through the boiler.

7. The oilfield steam injection boiler exhaust system according to claim 6, characterized in that: It also includes a cooling tower connected in series to the water circulation pipeline, and the cooling tower is also connected to cooling water.

8. The oilfield steam injection boiler exhaust system according to claim 1, characterized in that: A three-way regulating valve is installed on the chimney, and the smoke treatment device is connected to one of the outlets of the three-way regulating valve.

9. A method for using the oilfield steam injection boiler exhaust system according to any one of claims 1 to 8, characterized in that: The steps include: S1: Turn on the burner and blower. The blower introduces air into the burner to assist combustion, and the boiler starts to run. S2: Turn on the carbon dioxide introduction device and the oxygen introduction device, and introduce carbon dioxide and oxygen into the mixer for mixing until a predetermined mixed concentration is reached; S3: When the boiler is running stably, the blower sends the carbon dioxide-oxygen mixed gas in the mixer into the flue gas condenser. At the same time, the flue gas discharged from the chimney enters the flue gas condenser and exchanges heat with the carbon dioxide-oxygen mixed gas in the flue gas condenser. The flue gas cooled by heat exchange enters the flue gas water separator. The flue gas carbon dioxide-oxygen mixed gas heated by heat exchange continues to be passed into the burner for combustion. S4: After the flue gas water separator separates the flue gas and water, the flue gas is discharged into the carbon dioxide inlet device.

10. The method for using the oilfield steam injection boiler exhaust system according to claim 9, characterized in that: The S3 also includes: the high-temperature flue gas passes through a water preheater before entering the flue gas water separator to heat circulating water, and the circulating water passes through a water circulation pipeline into the boiler to heat boiler water.

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