Gas field produced water hydrogen, lithium, heat, electricity and oil co-production method

Abstract

According to the hydrogen lithium thermoelectric oil co-production method for the gas field produced water, comprehensive utilization of the gas field produced water is achieved, photovoltaic power or wind power serves as power, condensate oil in the water is recycled through the sedimentation microfiltration unit, the obtained pretreated water is fed into the deep treatment unit to be treated, demineralized water and strong brine are obtained, and the strong brine is used for lithium extraction of a brine lithium extraction device; the demineralized water is used for hydrogen production of the alkaline water electrolysis device, and waste heat generated in the hydrogen production process is used for evaporation and zero discharge of concentrated water after lithium extraction, so that condensate oil, lithium and waste heat in the produced water treatment and hydrogen production process are recycled, and finally zero discharge of wastewater and closed loop of new energy are realized.

Description

Technical Field

[0001] This invention belongs to the technical field of gas field produced water co-production methods, specifically relating to a gas field produced water hydrogen-lithium thermal power-oil co-production method. Background Technology

[0002] The Changqing Gas Field produces approximately 2.47 million cubic meters of produced water annually. Some of this produced water contains 500-150,000 mg / L of condensate oil and 6-80 mg / L of lithium. After treatment, it is estimated that 66,000 tons of hydrogen can be produced annually. However, currently, this is not effectively reinjected into the formation. Furthermore, the waste heat generated during the water electrolysis hydrogen production process is currently being dissipated by the supporting cooling towers, and the thermal energy is not being effectively utilized. There is an urgent need for resource utilization. If waste can be turned into treasure, environmental problems can be solved while generating resources. This would be of great significance for optimizing the energy structure of China's upstream oil and gas business and could further achieve deep decarbonization and a green and low-carbon transformation of oil and gas field development. Summary of the Invention

[0003] The purpose of this invention is to provide a method for the co-production of hydrogen, lithium, thermal power, and oil from produced water in gas fields, which solves the problem that existing methods for ineffective reinjection of produced water into the formation are ineffective.

[0004] The technical solution adopted in this invention is a method for co-producing hydrogen, lithium, thermal power, and oil from produced water in gas fields, comprising the following steps: Step 1: The produced water from the gas field is sent to a sedimentation microfiltration unit for separation and filtration to obtain condensate oil and pretreated water, and the condensate oil product is sent out. Step 2: Send the pretreated water obtained in Step 1 into the deep treatment unit for filtration and desalination to obtain desalinated water and concentrated brine; Step 3: The demineralized water obtained in Step 2 is sent to an alkaline water electrolysis device to produce hydrogen (AWE) through alkaline water electrolysis. The hydrogen product is then sent out. Step 4: Send the concentrated brine obtained in Step 2 into the brine lithium extraction device to extract lithium and obtain lithium salt and concentrated water, and send out the lithium salt product. Step 5: The waste heat generated by the alkaline solution from the alkaline water electrolysis device in Step 3 is sent to the MVR evaporation device to heat and evaporate the concentrated water obtained in Step 4 to crystallize it. In steps 1 to 5, the sedimentation microfiltration unit, the deep treatment unit, the alkaline water electrolysis device, the brine lithium extraction device, and the MVR evaporation device are all powered by photovoltaic or wind power.

[0005] The invention is further characterized in that, The sedimentation microfiltration unit in step 1 includes a sedimentation tank and a microfiltration (MF) filter. First, the gas field produced water is sent to the sedimentation tank for gravity sedimentation separation to obtain condensate oil and de-oiled water. Then, the de-oiled water is sent to the microfiltration filter for membrane separation to remove impurities and obtain pretreated water.

[0006] The advanced treatment unit in step 2 includes an ultrafiltration (UF) filter, a nanofiltration (NF) filter, a reverse osmosis (RO) filter, and an electrodialysis (EDI) unit. First, the pretreated water is sequentially fed into the ultrafiltration filter, nanofiltration filter, and reverse osmosis filter for membrane separation to remove impurities and obtain filtered water. Then, the filtered water is sent to the electrodialysis unit for continuous electro-desalination to obtain desalinated water and concentrated brine.

[0007] The alkaline water electrolysis device in step 3 is an alkaline electrolysis cell. The temperature of the alkaline solution in the alkaline electrolysis cell is controlled at 80~90℃. The demineralized water is sent into the alkaline electrolysis cell for electrolysis to obtain hydrogen and oxygen.

[0008] The brine lithium extraction device in step 4 is a continuous ion exchange device or a centrifugal extractor.

[0009] The beneficial effects of this invention are as follows: The gas field produced water hydrogen-lithium cogeneration method of this invention realizes the comprehensive utilization of gas field produced water. Powered by green electricity, the condensate oil in the water is recovered through the front end of the produced water deep treatment. The concentrated brine in the deep treatment process is used for lithium extraction. The demineralized water after deep treatment is used for hydrogen production. The waste heat generated in the hydrogen production process is used for the evaporation of the concentrated water after lithium extraction, resulting in zero discharge. Thus, the condensate oil, lithium, and waste heat in the produced water treatment and hydrogen production process are recovered and utilized, ultimately achieving zero wastewater discharge and a closed loop of new energy. Attached Figure Description

[0010] Figure 1 This is a schematic flowchart of the gas field produced water hydrogen-lithium thermal power oil cogeneration method of the present invention. Detailed Implementation

[0011] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0012] Example 1 This invention provides a method for co-producing hydrogen, lithium, thermal power, and oil from produced water in gas fields, such as... Figure 1 As shown, it includes the following steps: Step 1: Gas field produced water containing 500 mg / L oil, 80 mg / L suspended solids, 6 mg / L lithium, and 10000 mg / L mineralization is sent to a settling microfiltration unit. The settling microfiltration unit includes a settling tank and a microfiltration filter. First, the gas field produced water is sent to the settling tank for gravity settling separation to obtain condensate oil and de-oiled water. The condensate oil product is then sent out. Next, the de-oiled water is sent to the microfiltration filter for membrane separation to remove impurities and obtain pretreated water.

[0013] Step 2: The pretreated water obtained in Step 1 is sent to the advanced treatment unit, which includes an ultrafiltration filter, a nanofiltration filter, a reverse osmosis filter, and an electrodialysis unit. First, the pretreated water is sequentially sent to the ultrafiltration filter, nanofiltration filter, and reverse osmosis filter for membrane separation to remove impurities and obtain filtered water. Then, the filtered water is sent to the electrodialysis unit for continuous electro-desalination to obtain desalinated water with a resistivity ≥105Ω•cm and concentrated brine. The concentrated brine contains concentrated lithium salts.

[0014] Step 3: Send the demineralized water obtained in Step 2 into an alkaline electrolysis tank or other alkaline water electrolysis device, control the temperature of the alkaline solution in the alkaline electrolysis tank to 80°C, and electrolyze to obtain hydrogen and oxygen, and send out the hydrogen product.

[0015] Step 4: The concentrated brine obtained in Step 2 is sent to a continuous ion exchange device or a centrifugal extractor or other brine lithium extraction device to extract lithium salt and concentrated brine, and the lithium salt product is then sent out.

[0016] Step 5: The waste heat generated by the alkali solution in step 3 is sent to the MVR evaporator to heat and evaporate the concentrated water obtained in step 4, achieving zero emissions.

[0017] In steps 1 to 5, the sedimentation microfiltration unit, the deep treatment unit, the alkaline water electrolysis device, the brine lithium extraction device, and the MVR evaporation device are all powered by photovoltaic or wind power.

[0018] Example 2 This invention provides a method for co-producing hydrogen, lithium, thermal power, and oil from produced water in gas fields, such as... Figure 1 As shown, it includes the following steps: Step 1: Gas field produced water containing 150,000 mg / L of oil, 200 mg / L of suspended solids, 80 mg / L of lithium, and 60,000 mg / L of mineralization is sent to a settling microfiltration unit. The settling microfiltration unit includes a settling tank and a microfiltration filter. First, the gas field produced water is sent to the settling tank for gravity settling separation to obtain condensate oil and de-oiled water. The condensate oil product is then sent out. Next, the de-oiled water is sent to the microfiltration filter for membrane separation to remove impurities and obtain pretreated water.

[0019] Step 2: The pretreated water obtained in Step 1 is sent to the advanced treatment unit, which includes an ultrafiltration filter, a nanofiltration filter, a reverse osmosis filter, and an electrodialysis unit. First, the pretreated water is sequentially sent to the ultrafiltration filter, nanofiltration filter, and reverse osmosis filter for membrane separation to remove impurities and obtain filtered water. Then, the filtered water is sent to the electrodialysis unit for continuous electro-desalination to obtain desalinated water with a resistivity ≥105Ω•cm and concentrated brine. The concentrated brine contains concentrated lithium salts.

[0020] Step 3: Send the demineralized water obtained in Step 2 into an alkaline electrolysis tank or other alkaline water electrolysis device, control the temperature of the alkaline solution in the alkaline electrolysis tank to 90°C, and electrolyze to obtain hydrogen and oxygen, and send out the hydrogen product.

[0021] Step 4: The concentrated brine obtained in Step 2 is sent to a continuous ion exchange device or a centrifugal extractor or other brine lithium extraction device to extract lithium salt and concentrated brine, and the lithium salt product is then sent out.

[0022] Step 5: The waste heat generated by the alkali solution in step 3 is sent to the MVR evaporator to heat and evaporate the concentrated water obtained in step 4, achieving zero emissions.

[0023] In steps 1 to 5, the sedimentation microfiltration unit, the deep treatment unit, the alkaline water electrolysis device, the brine lithium extraction device, and the MVR evaporation device are all powered by photovoltaic or wind power.

[0024] Example 3 This invention provides a method for co-producing hydrogen, lithium, thermal power, and oil from produced water in gas fields, such as... Figure 1 As shown, it includes the following steps: Step 1: Gas field produced water containing 5000 mg / L oil, 100 mg / L suspended solids, 12 mg / L lithium, and 20000 mg / L mineralization is sent to a settling microfiltration unit. The settling microfiltration unit includes a settling tank and a microfiltration filter. First, the gas field produced water is sent to the settling tank for gravity settling separation to obtain condensate oil and de-oiled water. The condensate oil product is then sent out. Next, the de-oiled water is sent to the microfiltration filter for membrane separation to remove impurities and obtain pretreated water.

[0025] Step 2: The pretreated water obtained in Step 1 is sent to the advanced treatment unit, which includes an ultrafiltration filter, a nanofiltration filter, a reverse osmosis filter, and an electrodialysis unit. First, the pretreated water is sequentially sent to the ultrafiltration filter, nanofiltration filter, and reverse osmosis filter for membrane separation to remove impurities and obtain filtered water. Then, the filtered water is sent to the electrodialysis unit for continuous electro-desalination to obtain desalinated water with a resistivity ≥105Ω•cm and concentrated brine. The concentrated brine contains concentrated lithium salts.

[0026] Step 3: Send the demineralized water obtained in Step 2 into an alkaline electrolysis tank or other alkaline water electrolysis device, control the temperature of the alkaline solution in the alkaline electrolysis tank to 82°C, and electrolyze to obtain hydrogen and oxygen, and send out the hydrogen product.

[0027] Step 4: The concentrated brine obtained in Step 2 is sent to a continuous ion exchange device or a centrifugal extractor or other brine lithium extraction device to extract lithium salt and concentrated brine, and the lithium salt product is then sent out.

[0028] Step 5: The waste heat generated by the alkali solution in step 3 is sent to the MVR evaporator to heat and evaporate the concentrated water obtained in step 4, achieving zero emissions.

[0029] In steps 1 to 5, the sedimentation microfiltration unit, the deep treatment unit, the alkaline water electrolysis device, the brine lithium extraction device, and the MVR evaporation device are all powered by photovoltaic or wind power.

[0030] Example 4 This invention provides a method for co-producing hydrogen, lithium, thermal power, and oil from produced water in gas fields, such as... Figure 1 As shown, it includes the following steps: Step 1: Gas field produced water containing 50,000 mg / L oil, 150 mg / L suspended solids, 30 mg / L lithium, and 30,000 mg / L mineralization is sent to a settling microfiltration unit. The settling microfiltration unit includes a settling tank and a microfiltration filter. First, the gas field produced water is sent to the settling tank for gravity settling separation to obtain condensate oil and de-oiled water. The condensate oil product is then sent out. Next, the de-oiled water is sent to the microfiltration filter for membrane separation to remove impurities and obtain pretreated water.

[0031] Step 2: The pretreated water obtained in Step 1 is sent to the advanced treatment unit, which includes an ultrafiltration filter, a nanofiltration filter, a reverse osmosis filter, and an electrodialysis unit. First, the pretreated water is sequentially sent to the ultrafiltration filter, nanofiltration filter, and reverse osmosis filter for membrane separation to remove impurities and obtain filtered water. Then, the filtered water is sent to the electrodialysis unit for continuous electro-desalination to obtain desalinated water with a resistivity ≥105Ω•cm and concentrated brine. The concentrated brine contains concentrated lithium salts.

[0032] Step 3: Send the demineralized water obtained in Step 2 into an alkaline electrolysis tank or other alkaline water electrolysis device, control the temperature of the alkaline solution in the alkaline electrolysis tank to 85°C, and electrolyze to obtain hydrogen and oxygen, and send out the hydrogen product.

[0033] Step 4: The concentrated brine obtained in Step 2 is sent to a continuous ion exchange device or a centrifugal extractor or other brine lithium extraction device to extract lithium salt and concentrated brine, and the lithium salt product is then sent out.

[0034] Step 5: The waste heat generated by the alkali solution in step 3 is sent to the MVR evaporator to heat and evaporate the concentrated water obtained in step 4, achieving zero emissions.

[0035] In steps 1 to 5, the sedimentation microfiltration unit, the deep treatment unit, the alkaline water electrolysis device, the brine lithium extraction device, and the MVR evaporation device are all powered by photovoltaic or wind power.

[0036] Through the above-described method, the gas field produced water hydrogen-lithium cogeneration method of the present invention realizes the comprehensive utilization of gas field produced water. Powered by green electricity, the condensate oil in the water is recovered through the front end of the produced water deep treatment. The concentrated brine in the deep treatment process is used for lithium extraction. The demineralized water after deep treatment is used for hydrogen production. The waste heat generated in the hydrogen production process is used for the evaporation of the concentrated water after lithium extraction, resulting in zero discharge. Thus, the condensate oil, lithium, and waste heat in the produced water treatment and hydrogen production process are recovered and utilized, ultimately achieving zero wastewater discharge and a closed loop of new energy.

Claims

1. A method for cogeneration of hydrogen, lithium, thermal power, and oil from produced water in a gas field, characterized in that, Includes the following steps: Step 1: The produced water from the gas field is sent to a sedimentation microfiltration unit for separation and filtration to obtain condensate oil and pretreated water, and the condensate oil product is sent out. Step 2: Send the pretreated water obtained in Step 1 into the deep treatment unit for filtration and desalination to obtain desalinated water and concentrated brine; Step 3: The demineralized water obtained in Step 2 is fed into an alkaline water electrolysis device to produce hydrogen, and the hydrogen product is then sent out. Step 4: Send the concentrated brine obtained in Step 2 into the brine lithium extraction device to extract lithium and obtain lithium salt and concentrated water, and send out the lithium salt product. Step 5: The waste heat generated by the alkaline solution from the alkaline water electrolysis device in Step 3 is sent to the MVR evaporation device to heat and evaporate the concentrated water obtained in Step 4 to crystallize it. In steps 1 to 5, the sedimentation microfiltration unit, the deep treatment unit, the alkaline water electrolysis device, the brine lithium extraction device, and the MVR evaporation device are all powered by photovoltaic or wind power.

2. The method for cogeneration of hydrogen, lithium, thermal power, and oil from produced water in gas fields as described in claim 1, characterized in that, The sedimentation microfiltration unit in step 1 includes a sedimentation tank and a microfiltration filter. First, the gas field produced water is sent to the sedimentation tank for gravity sedimentation separation to obtain condensate oil and de-oiled water. Then, the de-oiled water is sent to the microfiltration filter for membrane separation to remove impurities and obtain pretreated water.

3. The method for cogeneration of hydrogen, lithium, thermal power, and oil from produced water in gas fields as described in claim 1, characterized in that, The advanced treatment unit in step 2 includes an ultrafiltration filter, a nanofiltration filter, a reverse osmosis filter, and an electrodialysis unit. First, the pretreated water is sequentially fed into the ultrafiltration filter, nanofiltration filter, and reverse osmosis filter for membrane separation to remove impurities and obtain filtered water. Then, the filtered water is sent to the electrodialysis unit for continuous electro-desalination to obtain desalinated water and concentrated brine.

4. The method for cogeneration of hydrogen, lithium, thermal power, and oil from produced water in gas fields as described in claim 1, characterized in that, The alkaline water electrolysis device in step 3 is an alkaline electrolysis cell, in which demineralized water is fed into the alkaline electrolysis cell to electrolyze and obtain hydrogen and oxygen.

5. The method for cogeneration of hydrogen, lithium, thermal power, and oil from produced water in gas fields as described in claim 4, characterized in that, In step 3, the temperature of the alkaline solution in the alkaline electrolytic cell is controlled to be 80~90℃.

6. The method for cogeneration of hydrogen, lithium, thermal power, and oil from produced water in gas fields as described in claim 1, characterized in that, The brine lithium extraction device in step 4 is a continuous ion exchange device.

7. The method for cogeneration of hydrogen, lithium, thermal power, and oil from produced water in gas fields as described in claim 1, characterized in that, The lithium extraction device from the brine in step 4 is a centrifugal extractor.

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