Resourceful treatment system for fireflooding produced gas in oil field

Abstract

The invention belongs to the technical field of fireflooding produced gas treatment, and particularly relates to an oilfield fireflooding produced gas resourceful treatment system. The system comprises a pretreatment unit and a resource utilization unit, the pretreatment unit comprises a cooling device, a purification device and a desulfurization device; the resource utilization unit comprises a circulating fluidized bed boiler and a carbon dioxide trapping device; the cooling device, the purification device, the desulfurization device, the circulating fluidized bed boiler and the carbon dioxide trapping device are connected in sequence; the pretreatment unit is used for performing cooling, dehumidification, impurity removal and desulfurization treatment on fireflooding produced gas; mixing the pretreated gas into a circulating fluidized bed boiler for mixed combustion; the combusted mixed gas enters a carbon dioxide trapping device for carbon dioxide gas trapping and recycling. Combustion utilization of combustible components such as methane and carbon monoxide in the produced gas is achieved, carbon dioxide in the mixed gas after combustion is captured and recycled, and resource utilization of the fireflooding produced gas is fully achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of fire drive produced gas processing, and in particular relates to a resource processing system for oil field fire drive produced gas. Background Art

[0002] Fire drive is a method of mining by injecting air into the formation from an injection well, igniting and burning the oil layer to form a radially moving combustion zone, and using the heat from the combustion of crude oil and air to increase the temperature of the oil layer, reduce the viscosity of crude oil, and enhance the fluidity of crude oil and the energy of the formation. During the combustion process, the oxygen in the air is consumed, and the remaining nitrogen, cracking gas and combustion gas are discharged through the production well to form fire drive tail gas. The composition of fire drive tail gas is complex, and the concentration of organic waste gas in the waste gas is high. The treatment methods are divided into two categories: recovery method and destruction method according to whether it has recycling value. Recovery methods include absorption method, adsorption method, condensation method and membrane separation method, and destruction methods include high-temperature incineration, catalytic combustion, biological oxidation and other technologies. Among them, the incineration method has the advantages of strong adaptability, high treatment efficiency and low investment cost, and is widely used in various emission industries, but this method fails to recycle the usable components in the fire drive produced gas and achieve resource treatment.

[0003] Patent document CN113731098A discloses a fire drive tail gas environmental protection resource treatment system and process flow, which mainly includes two process steps: dry desulfurization and pressure swing adsorption. The dry desulfurization is used to reduce the hydrogen sulfide content to less than 10 mg / m 3 , the methane in the fire drive tail gas is concentrated by pressure swing adsorption denitrification to obtain methane-rich gas, which is then transported to the pipeline network as fuel gas. However, the process flow of this patent fails to recover and utilize the carbon dioxide, which accounts for about 15% of the produced gas from the fire drive, and fails to fully achieve resource processing.

[0004] Patent document CN107725018A discloses a treatment system for fire-driven tail gas, which dries and desulfurizes the fire-driven tail gas, separates carbon dioxide and nitrogen, separates the harmful gas hydrogen sulfide, and further separates and utilizes the different components of carbon dioxide and nitrogen in the tail gas. However, the method of the patent does not realize the utilization of alkane components such as methane and carbon monoxide in the fire-driven tail gas, and the resource recovery rate needs to be further improved. Summary of the invention

[0005] The present invention aims to solve the technical problems existing in the background technology and provide a resource processing system for oilfield fire-driven produced gas. The fire-driven produced gas is introduced into a coal-fired circulating fluidized bed boiler for thermal oxidation treatment, mixed with the primary and secondary air of the boiler to enter the furnace for combustion, so as to realize the recovery and utilization of methane, carbon monoxide and other components in the fire-driven produced gas as fuel, so that the components can provide heat for the boiler after being burned as fuel; at the same time, the carbon dioxide in the mixed gas after combustion is recovered by a carbon dioxide capture device, so as to more fully realize the resource utilization of the fire-driven produced gas.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] An oilfield fire-driven produced gas resource processing system, comprising a pre-processing unit and a resource utilization unit;

[0008] The pretreatment unit is used to sequentially perform cooling, impurity removal and desulfurization pretreatment on the fire drive produced gas, and the resource utilization unit is used to mix the pretreated gas into a circulating fluidized bed boiler for mixed combustion, and to capture carbon dioxide from the mixed gas after combustion and reuse it;

[0009] The pretreatment unit includes a cooling device, a purification device and a desulfurization device, and the resource utilization unit includes a circulating fluidized bed boiler and a carbon dioxide capture device; the cooling device, the purification device, the desulfurization device, the circulating fluidized bed boiler and the carbon dioxide capture device are connected in sequence.

[0010] Furthermore, the carbon dioxide capture device comprises an air induction device, a flue gas separation device and a gas recovery device which are connected in sequence;

[0011] The induced draft device is used to introduce the mixed gas after combustion in the circulating fluidized bed boiler into the flue gas separation device;

[0012] The flue gas separation device is used to separate the carbon dioxide in the mixed gas and transport it to the gas recovery device, and the remaining tail gas is discharged in compliance with the emission standards.

[0013] Furthermore, a booster compressor is provided between the flue gas separation device and the gas recovery device for pressurizing the separated carbon dioxide.

[0014] Furthermore, the gas recovery device is a gas storage device for storing pressurized carbon dioxide.

[0015] Furthermore, the gas recovery device is an injection compressor, which is used to re-pressurize the pressurized carbon dioxide and then inject it back into the oil reservoir for oil recovery.

[0016] Furthermore, the flue gas separation device uses a chemical absorption method to capture carbon dioxide.

[0017] Furthermore, the flue gas separation device uses an amine method to capture carbon dioxide.

[0018] Furthermore, the flue gas separation device is provided with a tail gas emission pipe, and the tail gas emission pipe is connected to a tail gas treatment unit, and the tail gas treatment unit discharges the tail gas after treating the tail gas to meet the standards.

[0019] Furthermore, the cooling device is an air cooler; the purification device is a high-efficiency gas purification device; the desulfurization device is a wet desulfurization device; and the induced draft device is an induced draft fan.

[0020] Furthermore, the circulating fluidized bed boiler is a coal-fired boiler, and the fire-driven produced gas and coal are mixed and burned by introducing the fire-driven produced gas into the boiler air supply duct, and entering the boiler furnace through the primary and secondary air ducts of the circulating fluidized bed boiler, and then an oxidation decomposition reaction occurs in the furnace.

[0021] Furthermore, when the fire drive produced gas is mixed with coal for combustion, the control measures for the amount of the fire drive produced gas added include:

[0022] Monitor the boiler flue gas flow rate online, and adjust the total amount of produced gas mixed with fire drive in real time according to the online monitored boiler flue gas flow rate, and control the total amount of produced gas mixed with fire drive to be ≤ 20% of the boiler flue gas flow rate;

[0023] Monitor the boiler furnace temperature online, and adjust the amount of fire drive produced gas added to the primary air duct in real time based on the online monitored boiler furnace temperature to ensure that the boiler furnace temperature is between 850℃ and 900℃;

[0024] Monitor the oxygen content of flue gas at the tail end of the boiler online, and adjust the amount of fire drive produced gas mixed into the secondary air duct in real time according to the oxygen content of the flue gas monitored online to ensure that the oxygen content of the flue gas at the tail end of the boiler is 3%-5%.

[0025] Furthermore, when the fire drive produced gas is mixed with the circulating fluidized bed boiler for combustion, the fire drive produced gas inlet pipeline is connected to the fire drive produced gas to boiler primary air pipeline transmission pipeline and the fire drive produced gas to boiler secondary air pipeline transmission pipeline respectively;

[0026] The fire drive produced gas is transported to the boiler primary air pipeline and the primary air inlet pipeline, and then transported to the common air preheater through the primary fan, and then mixed with the primary air into the boiler pipeline to enter the boiler furnace for combustion;

[0027] The fire drive produced gas is transported to the boiler secondary air pipeline and the secondary air inlet pipeline, and then transported to the common air preheater through the secondary fan, and then enters the boiler furnace through the mixed secondary air inlet boiler pipeline for combustion;

[0028] An electric regulating valve and a gas flow meter are arranged on the gas pipeline of the produced gas from the fire drive; an electric regulating valve is arranged on the pipeline from the produced gas from the fire drive to the primary air pipeline of the boiler and on the pipeline from the produced gas from the fire drive to the secondary air pipeline of the boiler.

[0029] Furthermore, manual stop valves are provided on the fire drive produced gas supply pipeline, the fire drive produced gas to boiler primary air pipeline transportation pipeline and the fire drive produced gas to boiler secondary air pipeline transportation pipeline, so as to timely cut off the transportation pipeline when a fire drive produced gas leakage safety failure occurs.

[0030] Furthermore, check valves are provided on the fire drive produced gas supply pipeline, the fire drive produced gas to boiler primary air pipeline transportation pipeline and the fire drive produced gas to boiler secondary air pipeline transportation pipeline to prevent backflow of combustion medium.

[0031] Furthermore, an alarm is also provided on the fire drive produced gas supply pipeline, and the alarm is provided downstream of the electric regulating valve of the fire drive produced gas supply pipeline to monitor whether harmful gas leakage occurs in the working environment;

[0032] The alarm is linked to the MFT trip protection system of the fluidized bed boiler for control. When the alarm detects that the harmful gas exceeds the standard, an alarm will be triggered, and the MFT trip protection system will be triggered to trip at the same time, and the electric regulating valve on the gas pipeline of the fire drive production gas will be cut off in a chain manner to achieve safety protection of the entire system.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] (1) The oilfield fire-driven produced gas resource processing system provided by the present invention first pre-treats and desulfurizes the fire-driven produced gas, then mixes it into a coal-fired circulating fluidized bed boiler for mixed combustion, and utilizes the combustion of combustible components such as methane and carbon monoxide in the produced gas to provide heat for the boiler, thereby reducing the fuel consumption of the boiler operation, and can reduce the coal consumption of the boiler by about 100 tons / day; at the same time, through the carbon dioxide capture device, the carbon dioxide in the mixed gas is recycled and stored or re-injected into the oil reservoir. Through the above method, the resource processing of the oilfield fire-driven produced gas is fully realized, and the resource utilization rate is high;

[0035] (2) Since the boiler flue gas contains smoke impurities, the use of traditional membrane separation methods is prone to membrane pollution, affecting the separation effect, and it is difficult to obtain high-purity carbon dioxide, which cannot meet the requirements of subsequent injection of recovered carbon dioxide into the oil reservoir for oil recovery. The oil field fire drive produced gas resource processing system provided by the present invention uses a chemical absorption method (such as an amine method) to separate carbon dioxide from the boiler flue gas. This method can better capture low-concentration carbon dioxide in the boiler flue gas, and has a better capture effect than the traditional membrane separation method.

[0036] (3) The oilfield fire-driven produced gas resource processing system provided by the present invention, when the fire-driven produced gas is mixed with coal for combustion, the fire-driven produced gas is introduced into the boiler air supply duct, and enters the boiler furnace by being mixed into the primary and secondary air ducts of the circulating fluidized bed boiler, and then an oxidation decomposition reaction occurs in the furnace; during the mixed combustion, the total amount of the fire-driven produced gas mixed is regulated in real time by online monitoring of the boiler flue gas flow, the amount of the fire-driven produced gas mixed into the primary air duct is regulated in real time by online monitoring of the boiler furnace temperature, and the amount of the fire-driven produced gas mixed into the secondary air duct is regulated in real time by online monitoring of the oxygen content of the flue gas at the tail end of the boiler, thereby improving the combustion efficiency while the coal-fired fluidized bed boiler is operating safely and stably, and realizing the maximum amount of fire-driven produced gas mixed combustion treatment;

[0037] (4) The oilfield fire drive produced gas resource processing system provided by the present invention can respectively add manual stop valves on the fire drive produced gas inlet pipeline before the fire drive produced gas enters the primary and secondary air ducts of the coal-fired circulating fluidized bed boiler and on the fire drive produced gas to the boiler primary and secondary air pipelines. In the event of a safety accident such as fire drive produced gas leakage, the corresponding pipeline can be cut off in time through the manual stop valve to ensure the production safety of the system; by respectively adding check valves on the fire drive produced gas inlet pipeline and on the fire drive produced gas to the boiler primary and secondary air pipelines, the combustion medium can be prevented from flowing back, thereby avoiding the primary air, The secondary air supply flows back into the fire drive produced gas pipeline, further ensuring the safe and stable operation of the system; an alarm is set on the downstream pipeline of the electric regulating valve on the fire drive produced gas pipeline to monitor whether the harmful gas leaks beyond the standard, and the alarm is linked with the MFT tripping protection system of the fluidized bed boiler. When the alarm sounds, the MFT tripping protection system is triggered to trip at the same time, and the electric regulating valve on the fire drive produced gas pipeline is cut off in a chain manner, thereby avoiding the leakage of toxic and harmful gases and preventing the workers from being poisoned by carbon monoxide and hydrogen sulfide, thereby achieving safety protection for the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the process of the oilfield fire drive produced gas resource processing system in Example 1 of the present invention;

[0039] Figure 2 This is a schematic diagram of the control structure of the pipeline before the fire drive produced gas is blended and burned into the coal-fired circulating fluidized bed boiler in Example 2 of the present invention;

[0040] Figure 3 This is a schematic diagram of the process of the oilfield fire drive produced gas resource processing system in Example 3 of the present invention;

[0041] Explanation of the markings in the figure: 1- air cooler; 2- high-efficiency gas purification device; 3- desulfurization device; 4- coal-fired circulating fluidized bed boiler; 5- induced draft device; 6- flue gas separation device; 7- tail gas discharge pipe; 8- booster compressor; 9- gas storage device; 10- injection compressor; 11- fire drive produced gas pipeline; 12- 1# electric regulating valve; 13- 1# manual stop valve; 14- 1# check valve; 15- gas flow meter; 16- fire drive produced gas to boiler primary air pipeline Conveying pipeline; 17-fire drive produced gas to boiler secondary air pipeline conveying pipeline; 18-2# electric regulating valve; 19-2# manual stop valve; 20-2# check valve; 21-3# electric regulating valve; 22-3# manual stop valve; 23-3# check valve; 24-primary air inlet pipeline; 25-secondary air inlet pipeline; 26-primary fan; 27-secondary fan; 28-air preheater; 29-mixed primary air into boiler pipeline; 30-mixed secondary air into boiler pipeline. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0043] Example 1

[0044] An embodiment of the present invention provides a resource processing system for oilfield fire-driven produced gas, comprising a pretreatment unit and a resource utilization unit; the pretreatment unit is used to perform pretreatments such as cooling, impurity removal and desulfurization on the fire-driven produced gas in sequence, and the resource utilization unit is used to mix the pretreated gas into a circulating fluidized bed boiler for mixed combustion, and to capture carbon dioxide from the mixed gas after combustion and reuse it.

[0045] Reference Figure 1 As shown, the pretreatment unit includes: an air cooler 1, a high-efficiency gas purification device 2 and a desulfurization device 3; the resource utilization unit includes a circulating fluidized bed boiler 4, an induced draft device 5, a flue gas separation device 6, a booster compressor 8 and a gas storage device 9; the air cooler 1, the high-efficiency gas purification device 2, the desulfurization device 3, the circulating fluidized bed boiler 4, the induced draft device 5, the flue gas separation device 6, the booster compressor 8 and the gas storage device 9 are connected in sequence.

[0046] Specifically, the produced gas from the fire drive in the oil gathering area is first introduced into the air cooler 1 through a pipeline for temperature reduction treatment.

[0047] The gas after the cooling treatment enters the high-efficiency gas purification device 2 for gas-liquid separation, smoke / impurity removal, etc., and removes small particles of dust and droplets (including water and oil droplets) ≥5μm.

[0048] The purified gas enters the desulfurization device 3 for desulfurization treatment. The desulfurization device 3 is a wet desulfurization device. The H2S concentration after desulfurization treatment is less than or equal to 15 mg / Nm 3 .

[0049] The outlet of the desulfurization device 3 is connected to the circulating fluidized bed boiler 4. The pretreated fire-driven produced gas enters the circulating fluidized bed boiler 4 and is mixed with coal for combustion. The fire-driven produced gas uses the heat generated by the combustion of coal in the boiler furnace to cause an oxidation decomposition reaction of the organic waste gas to generate carbon dioxide and water. The methane, carbon monoxide and other combustible components in the produced gas are burned in the furnace to act as a part of the fuel to provide heat. The produced gas after thermal oxidation treatment enters the boiler flue gas treatment and emission system with the boiler flue gas to capture and recover carbon dioxide and treat and discharge tail gas.

[0050] The circulating fluidized bed boiler 4 is a coal-fired boiler. The fire-driven produced gas and coal are mixed to introduce the fire-driven produced gas into the boiler air supply duct, and then enter the boiler furnace through the primary and secondary air ducts of the circulating fluidized bed boiler, and then an oxidation decomposition reaction occurs in the furnace.

[0051] In some embodiments, the circulating fluidized bed boiler can also be configured to be used in parallel in multiple units according to actual project needs to increase the processing capacity of the fire drive produced gas.

[0052] The induced draft device 5 is connected to the circulating fluidized bed boiler 4 . The induced draft device 5 is an induced draft fan for introducing the mixed gas after combustion in the boiler furnace into the flue gas separation device 6 .

[0053] Since the boiler flue gas contains smoke impurities, the use of traditional membrane separation methods is prone to membrane pollution, affecting the separation effect, and it is difficult to obtain high-purity carbon dioxide, which cannot meet the requirements of subsequent reinjection of recovered carbon dioxide into the oil reservoir for oil recovery. Therefore, the flue gas separation device 6 in the embodiment of the present invention adopts a chemical absorption method to separate the carbon dioxide in the boiler flue gas, specifically the amine method. This method can better capture lower concentrations of carbon dioxide in the boiler flue gas, and has better capture effect than the traditional membrane separation method.

[0054] The flue gas separation device 6 is provided with a tail gas emission pipe 7, and the flue gas separation device 6 is used to separate the carbon dioxide in the mixed gas and transport it to the booster compressor 8. The remaining tail gas is transported to the tail gas treatment unit through the tail gas emission pipe 7 for treatment, so that the dust, SO2, NOx and other contents in the flue gas meet the local boiler flue gas environmental protection index requirements before being discharged.

[0055] The booster compressor 8 is used to pressurize the carbon dioxide separated from the flue gas and transport the pressurized carbon dioxide to the gas storage device 9 for storage.

[0056] Example 2

[0057] The embodiment of the present invention is based on the embodiment 1, and the amount of fire-driven produced gas added to the coal-fired fluidized bed boiler is effectively controlled. Under the premise of ensuring the safe and stable operation of the circulating fluidized bed boiler, the combustion efficiency is improved and the amount of fire-driven produced gas is maximized by the blending treatment.

[0058] like Figure 3 The figure shows a flow diagram of the oilfield fire-driven produced gas resource processing system in an embodiment of the present invention, wherein the fire-driven produced gas inlet pipeline 11 is respectively connected to the fire-driven produced gas to boiler primary air pipeline transportation pipeline 16 and the fire-driven produced gas to boiler secondary air pipeline transportation pipeline 17; the fire-driven produced gas to boiler primary air pipeline transportation pipeline 16 and the primary air inlet pipeline 24 are combined, and then transported to a common air preheater 28 through a primary air fan 26, and then enter the boiler furnace for combustion through a mixed primary air inlet boiler pipeline 29; the fire-driven produced gas to boiler secondary air pipeline transportation pipeline 17 and the secondary air inlet pipeline 25 are combined, and then transported to a common air preheater 28 through a secondary air fan 27, and then enter the boiler furnace for combustion through a mixed secondary air inlet boiler pipeline 30.

[0059] Among them, the fire drive produced gas inlet pipeline 11 is provided with a 1# electric regulating valve 12 and a gas flow meter 15; the fire drive produced gas to the boiler primary air pipeline transmission pipeline 16 is provided with a 2# electric regulating valve 18; the fire drive produced gas to the boiler secondary air pipeline transmission pipeline 17 is provided with a 3# electric regulating valve 21.

[0060] The control of the amount of produced gas added to the fire drive in the coal-fired fluidized bed boiler includes the following control measures:

[0061] (1) Online monitoring of boiler flue gas flow, generally using a CEMS flue gas emission continuous monitoring system to perform online detection of flue gas flow, smoke dust and flue gas parameters, and based on the online monitored boiler flue gas flow, real-time control of the total amount of fire drive produced gas mixed, specifically through the 1# electric regulating valve 12 and the gas flow meter 15 to control the total amount of fire drive produced gas mixed, control the total amount of fire drive produced gas mixed ≤ 20% of the boiler flue gas flow, thereby reducing the impact of mixed combustion on the thermal efficiency of the boiler and ensuring stable combustion of the boiler;

[0062] (2) Online monitoring of the boiler furnace temperature, and real-time regulation of the amount of the fire-driven produced gas mixed into the primary air duct according to the online monitored boiler furnace temperature. Specifically, the amount of the fire-driven produced gas mixed into the primary air duct is regulated by the No. 2 electric regulating valve 18 on the boiler primary air pipeline 16 from the fire-driven produced gas to the boiler to ensure that the boiler furnace temperature is between 850°C and 900°C, so that the bed temperature of the circulating fluidized bed boiler is distributed within an appropriate range, which is conducive to efficient staged combustion of the circulating fluidized bed boiler;

[0063] (3) Online monitoring of the oxygen content of flue gas at the tail end of the boiler, and real-time regulation of the amount of the produced gas from the fire drive gas mixed into the secondary air duct according to the oxygen content of the flue gas monitored online. Specifically, the amount of the produced gas from the fire drive gas mixed into the secondary air duct is regulated by the 3# electric regulating valve 21 on the secondary air pipeline 17 of the boiler, so as to ensure that the oxygen content of the flue gas at the tail end of the boiler is 3%-5%, so as to ensure a reasonable excess air coefficient in the boiler furnace, so as to ensure safe and economical operation of the boiler;

[0064] At the same time, in order to ensure the safety of the mixed combustion of the produced gas from fire drive into the coal-fired fluidized bed boiler, the following measures are adopted:

[0065] (1) A 1# manual stop valve 13, a 2# manual stop valve 19 and a 3# manual stop valve 22 are respectively provided on the fire drive produced gas inlet pipeline 11, the fire drive produced gas to boiler primary air pipeline transmission pipeline 16, and the fire drive produced gas to boiler secondary air pipeline transmission pipeline 17, so as to timely cut off the corresponding pipelines through the manual stop valves when a safety accident such as fire drive produced gas leakage occurs, thereby blocking the transmission of fire drive produced gas and ensuring the production safety of the system;

[0066] (2) A No. 1 check valve 14, a No. 2 check valve 20 and a No. 3 check valve 23 are respectively installed on the fire drive produced gas supply pipeline 11, the fire drive produced gas to the boiler primary air pipeline delivery pipeline 16, and the fire drive produced gas to the boiler secondary air pipeline delivery pipeline 17. The check valves can prevent the combustion medium from flowing back, and prevent the primary air and secondary air from flowing back into the fire drive produced gas pipeline, thereby further ensuring the safe and stable operation of the system;

[0067] (2) An alarm is also provided on the fire drive produced gas inlet pipeline 11. The alarm is provided downstream of the 1# electric regulating valve 12 of the fire drive produced gas inlet pipeline 11 and is used to monitor whether harmful gases such as carbon monoxide and hydrogen sulfide leak in the working environment; the alarm is linked to the MFT tripping protection system of the fluidized bed boiler for control. When the alarm detects that the harmful gas exceeds the standard, it will issue an audible and visual alarm prompt, and at the same time trigger the MFT tripping protection system to trip, and interlock and cut off the 1# electric regulating valve 12 on the fire drive produced gas inlet pipeline 11, thereby avoiding the leakage of toxic and harmful gases and preventing the workers from being poisoned by carbon monoxide and hydrogen sulfide, thereby achieving safety protection for the entire system.

[0068] Example 3

[0069] In the embodiment of the present invention, based on the embodiment 1 or 2, the gas storage device 9 is replaced by an injection compressor 10 .

[0070] The injection compressor 10 is used to re-pressurize the pressurized carbon dioxide and then inject it back into the oil reservoir for oil recovery.

[0071] Example 4

[0072] This embodiment of the present invention is based on Embodiment 3 and processes the fire-driven produced gas of a certain oil field to further illustrate the overall process flow of the fire-driven produced gas resource processing system of the present invention.

[0073] Combination Figure 1 As shown in or 2, the system includes the following devices: an air cooler 1, a high-efficiency gas purification device 2, a desulfurization device 3, a circulating fluidized bed boiler 4, an induced draft fan 5, a flue gas separation device 6, an exhaust gas discharge pipe 7, a booster compressor 8, a gas storage device 9 or an injection compressor 10.

[0074] The daily output of gas produced by fire drive in this oil field is about 70×10 4 Nm 3 / d, the composition of the produced gas from fire drive is shown in Table 1:

[0075] Table 1 Composition of produced gas from fire drive

[0076]

[0077] The process flow of the fire drive produced gas resource processing system according to the embodiment of the present invention specifically includes the following steps:

[0078] The fire drive produced gas (temperature T = 30-60°C) in the oil field first enters the air cooler 1 for cooling, and the temperature is reduced to 30-40°C.

[0079] The outlet of the air cooler 1 is connected to the high-efficiency gas purification device 2 through a pipeline to perform gas-liquid separation and dust removal, solid removal, and remove small dust particles ≥ 5μm and oil droplets.

[0080] The outlet of the high-efficiency gas purification device 2 is connected to the desulfurization device 3 through a pipeline. The desulfurization device 3 is a wet desulfurization device, which removes H2S in the fire drive produced gas to 15mg / m 3 .

[0081] The outlet of the desulfurization device 3 is connected to the circulating fluidized bed boiler 4 through a pipeline. The circulating fluidized bed boiler 4 described in the embodiment of the present invention is two coal-fired circulating fluidized bed boilers. The two coal-fired fluidized bed boilers each process half of the fire drive produced gas flow rate, and the half of the fire drive produced gas flow rate is about 14583Nm 3 / h. The total hydrocarbons in the produced gas from fire drive are oxidized and decomposed in the furnace of the coal-fired circulating fluidized bed boiler and enter the flue gas treatment system of the coal-fired circulating fluidized bed boiler along with the flue gas generated by the boiler.

[0082] The components of the boiler flue gas before and after the thermal oxidation treatment of the fire-driven produced gas in the circulating fluidized bed boiler 4 are shown in Table 2 below; it can be seen that after the fire-driven produced gas is mixed into the coal-fired fluidized bed boiler 4 for thermal oxidation dehydrogenation, the concentrations of CO2 and N2 increase slightly, and the concentrations of SO2 and O2 decrease slightly, and the changes of the main gas components before and after mixing are not obvious.

[0083] Table 2 Composition of flue gas components before and after coal-fired circulating fluidized bed mixed combustion fire flooding produced gas

[0084] Components <![CDATA[CO2]]> <![CDATA[SO2]]> <![CDATA[H2O]]> <![CDATA[N2]]> <![CDATA[O2]]> Content before blending 11.8％ 0.04％ 9.00％ 73.59％ 5.57％ Content after blending 12.00％ 0.03％ 8.55％ 74.39％ 5.02％

[0085] The outlet of the flue gas treatment device of the circulating fluidized bed boiler 4 is connected to the induced draft fan 5 through a pipeline, and the outlet of the induced draft fan 5 is connected to the flue gas separation device 6. The flue gas separation device 6 separates carbon dioxide in the boiler flue gas by chemical absorption.

[0086] The flue gas separation device 6 connects the separated carbon dioxide gas to the booster compressor 8, and the remaining exhaust gas is transported to the exhaust gas treatment unit through the exhaust gas exhaust pipe 7 for treatment, so that the dust, SO2, NOx and other contents in the flue gas meet the local boiler flue gas environmental protection index requirements before being discharged.

[0087] The booster compressor 8 pressurizes the carbon dioxide and transports the pressurized carbon dioxide to the gas storage device 9 for storage. Alternatively, the booster compressor 8 is connected to the injection compressor 10, and the injection compressor 10 pressurizes the pressurized carbon dioxide for a second time and then injects it back into the oil reservoir for oil recovery.

[0088] The system of the embodiment of the present invention realizes the resource processing of fire-driven produced gas. After the fire-driven produced gas is pre-treated and desulfurized, it is subjected to thermal oxidation treatment in a coal-fired circulating fluidized bed boiler, which can reduce the boiler's coal consumption by about 100 tons / day, and capture, recycle and utilize the carbon dioxide in the mixed gas after combustion, fully realizing the resource processing of fire-driven produced gas with high resource utilization rate.

[0089] The above description is only an embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the application scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system for processing oilfield fire-driven produced gas resources, characterized in that: It includes a pre-processing unit and a resource utilization unit; The pretreatment unit is used to sequentially perform cooling, impurity removal and desulfurization pretreatment on the fire drive produced gas, and the resource utilization unit is used to mix the pretreated gas into a circulating fluidized bed boiler for mixed combustion, and to capture carbon dioxide from the mixed gas after combustion and reuse it; The pretreatment unit includes a cooling device, a purification device and a desulfurization device, and the resource utilization unit includes a circulating fluidized bed boiler and a carbon dioxide capture device; The cooling device, purification device, desulfurization device, circulating fluidized bed boiler and carbon dioxide capture device are connected in sequence.

2. The system according to claim 1, characterized in that The carbon dioxide capture device comprises an induced draft device, a flue gas separation device and a gas recovery device connected in sequence; The induced draft device is used to introduce the mixed gas after combustion in the circulating fluidized bed boiler into the flue gas separation device; The flue gas separation device is used to separate the carbon dioxide in the mixed gas and transport it to the gas recovery device, and the remaining tail gas is discharged in compliance with the emission standards.

3. The system according to claim 2, characterized in that A booster compressor is provided between the flue gas separation device and the gas recovery device for pressurizing the separated carbon dioxide.

4. The system according to claim 3, characterized in that The gas recovery device is a gas storage device used to store pressurized carbon dioxide.

5. The system according to claim 3, characterized in that The gas recovery device is an injection compressor, which is used to re-pressurize the pressurized carbon dioxide and then inject it back into the oil reservoir for oil recovery.

6. The system according to claim 2, characterized in that The flue gas separation device captures carbon dioxide using a chemical absorption method.

7. The system according to claim 6, characterized in that The flue gas separation device uses the alcohol amine method to capture carbon dioxide.

8. The system according to claim 2, characterized in that The flue gas separation device is provided with a tail gas emission pipe, and the tail gas emission pipe is connected to a tail gas treatment unit, and the tail gas treatment unit discharges the tail gas after the tail gas meets the standards.

9. The system according to claim 2, characterized in that The cooling device is an air cooler; the purification device is a high-efficiency gas purification device; the desulfurization device is a wet desulfurization device; and the induced draft device is an induced draft fan.

10. The system according to any one of claims 1 to 9, characterized in that: The circulating fluidized bed boiler is a coal-fired boiler. The fire-driven produced gas and coal are mixed and burned by introducing the fire-driven produced gas into the boiler air supply duct, mixing it into the primary and secondary air ducts of the circulating fluidized bed boiler and entering the boiler furnace, and then an oxidation decomposition reaction occurs in the furnace.

11. The system according to claim 10, characterized in that When the fire drive produced gas is mixed with coal for combustion, the control measures for the amount of the fire drive produced gas added include: Monitor the boiler flue gas flow rate online, and adjust the total amount of produced gas mixed with fire drive in real time according to the online monitored boiler flue gas flow rate, and control the total amount of produced gas mixed with fire drive to be ≤ 20% of the boiler flue gas flow rate; Monitor the boiler furnace temperature online, and adjust the amount of fire drive produced gas added to the primary air duct in real time based on the online monitored boiler furnace temperature to ensure that the boiler furnace temperature is between 850℃ and 900℃; Monitor the oxygen content of flue gas at the tail end of the boiler online, and adjust the amount of fire drive produced gas mixed into the secondary air duct in real time according to the oxygen content of the flue gas monitored online to ensure that the oxygen content of the flue gas at the tail end of the boiler is 3%-5%.

12. The system according to claim 11, characterized in that When the fire drive produced gas is mixed with the circulating fluidized bed boiler for combustion, the fire drive produced gas inlet pipeline is connected to the fire drive produced gas to boiler primary air pipeline transmission pipeline and the fire drive produced gas to boiler secondary air pipeline transmission pipeline respectively; The fire drive produced gas is transported to the boiler primary air pipeline and the primary air inlet pipeline, and then transported to the common air preheater through the primary fan, and then mixed with the primary air into the boiler pipeline to enter the boiler furnace for combustion; The fire drive produced gas is transported to the boiler secondary air pipeline and the secondary air inlet pipeline, and then transported to the common air preheater through the secondary fan, and then enters the boiler furnace through the mixed secondary air inlet boiler pipeline for combustion; An electric regulating valve and a gas flow meter are arranged on the gas pipeline of the produced gas from the fire drive; an electric regulating valve is arranged on the pipeline from the produced gas from the fire drive to the primary air pipeline of the boiler and on the pipeline from the produced gas from the fire drive to the secondary air pipeline of the boiler.

13. The system according to claim 12, characterized in that Manual stop valves are installed on the fire drive produced gas supply pipeline, the fire drive produced gas to boiler primary air pipeline transportation pipeline and the fire drive produced gas to boiler secondary air pipeline transportation pipeline, which are used to cut off the transportation pipeline in time when a fire drive produced gas leakage safety failure occurs.

14. The system according to claim 12, characterized in that Check valves are installed on the gas pipeline of the fire drive produced gas, the pipeline of the fire drive produced gas to the boiler primary air pipeline, and the pipeline of the fire drive produced gas to the boiler secondary air pipeline to prevent the backflow of the combustion medium.

15. The system according to claim 12, characterized in that An alarm is also provided on the fire drive produced gas supply pipeline, and the alarm is provided downstream of the electric regulating valve of the fire drive produced gas supply pipeline, and is used to monitor whether harmful gas leakage occurs in the working environment; The alarm is linked to the MFT trip protection system of the fluidized bed boiler for control. When the alarm detects that the harmful gas exceeds the standard, it will issue an alarm prompt and simultaneously trigger the MFT trip protection system to trip, thereby interlocking and cutting off the electric regulating valve on the fire drive produced gas pipeline to achieve safety protection for the entire system.

Images