Green electricity energy storage parallel coupling oil field steam huff and puff and solid waste treatment process system

Abstract

The utility model discloses a green electricity energy storage parallel coupling oil field steam huff and puff and solid waste treatment process system. The utility model belongs to the field of energy conservation and environmental protection, and particularly relates to a green electricity energy storage parallel coupling oil field steam huff and puff and solid waste treatment process system. The utility model aims to fully consume green electricity resources, guarantee the balance and stability of a power grid, reduce fossil energy consumption in the traditional steam huff and puff and oil sludge treatment process, reduce the oil sludge solid waste storage and transportation cost and overcome the difficult problems of high-temperature decomposition of heat-conducting oil and low-temperature solidification of fused salt. The stable operation of the steam huff-puff and oil sludge treatment coupling process is ensured. The system comprises a first-stage steam system, a second-stage steam system, a molten salt system, an oil sludge treatment first-stage system and an oil sludge treatment second-stage system. The device is used for parallel coupling oil field steam huff and puff and solid waste treatment.

Description

Technical Field

[0001] The present invention belongs to the field of energy conservation and environmental protection, and specifically relates to a process system for parallel coupling of oilfield steam stimulation and solid waste disposal by using green electricity energy storage. Background Art

[0002] The steam stimulation process is a thermal recovery technology used in the process of oil exploitation to improve the oilfield recovery efficiency. By injecting high-temperature and high-pressure steam into the oil layer, the fluidity of crude oil is improved, and the viscosity and surface tension are reduced, so as to obtain a higher oil production recovery rate. At present, high-temperature and high-pressure steam is generated by burning natural gas in a steam injection furnace to heat feed water. This process consumes a large amount of natural gas, and natural gas is an important chemical raw material in the chemical industry. The economic value generated by incineration is significantly low. Therefore, there is a large room for improvement in the economy of the steam stimulation process at the present stage.

[0003] In addition, a large amount of oily sludge (referred to as oil sludge for short) will be generated during the processes of oil exploitation, storage, transportation and refining, and it must be treated before it can be discharged. At present, pyrolysis is widely used for oil sludge disposal, and the heat source is usually natural gas combustion. The pyrolysis of oil sludge also consumes a large amount of natural gas, resulting in relatively serious energy waste and high carbon emissions.

[0004] Since oilfields usually have a vast area, Chinese oilfields usually configure certain renewable energy power generation facilities such as wind power, photovoltaic power or solar thermal power. However, the green electricity generated by renewable energy has strong volatility. Connecting to the power grid is likely to damage the stability of the power grid and cause an impact on the power grid capacity and carrying capacity. Therefore, energy storage technology needs to be introduced to store green electricity. However, the existing industrial system in oilfields is relatively mature, and there are bottlenecks in the green electricity consumption capacity. Summary of the Invention

[0005] The purpose of the present invention is to fully consume green electricity resources, ensure the balance and stability of the power grid, reduce the consumption of fossil energy in traditional steam stimulation and oil sludge disposal processes, reduce the storage and transportation costs of oil sludge solid waste, overcome the problems of high-temperature decomposition of heat transfer oil and low-temperature solidification of molten salt, and ensure the stable operation of the coupling process of steam stimulation and oil sludge disposal. Furthermore, a process system for parallel coupling of oilfield steam stimulation and solid waste disposal by using green electricity energy storage is provided.

[0006] The process system for parallel coupling of oilfield steam stimulation and solid waste disposal by using green electricity energy storage of the present invention includes a primary steam system, a secondary steam system, a molten salt system, a first-stage oil sludge treatment system and a second-stage oil sludge treatment system; the primary steam system includes a heat transfer oil heat exchanger, a heat transfer oil electric heater and a heat transfer oil tank, and uses heat transfer oil as a heat exchange medium to heat low-temperature and high-pressure feed water into medium-temperature and high-pressure superheated steam.

[0007] The secondary steam system includes a molten salt heat exchanger that uses high-temperature molten salt as a heat transfer medium to heat medium-temperature high-pressure superheated steam into high-temperature high-pressure superheated steam, which is used as the steam for the steam huff and puff process.

[0008] The molten salt system includes a low-temperature salt tank, a molten salt electric heater, and a high-temperature salt tank, which uses green electricity as an energy source to heat low-temperature molten salt into high-temperature molten salt.

[0009] The primary oil sludge treatment system includes an oil sludge drying device that uses high-temperature heat transfer oil as a heat transfer medium to dry wet oil sludge into dry oil sludge and generate evaporation gas at the same time.

[0010] The secondary oil sludge treatment system includes a molten salt-heated oil sludge pyrolyzer, a condenser, and a coke incinerator. The high-temperature molten salt stored in the high-temperature salt tank is used as a heat transfer medium and introduced into the molten salt-heated oil sludge pyrolyzer to pyrolyze dry oil sludge to produce syngas and coke. The syngas generated from the pyrolysis of dry oil sludge in the molten salt-heated oil sludge pyrolyzer is cooled and separated into oil and water in the condenser to produce condensed water, pyrolysis oil, and non-condensable gas. The coke generated from the pyrolysis of dry oil sludge in the molten salt-heated oil sludge pyrolyzer, the evaporation gas generated from the drying of wet oil sludge in the oil sludge drying device, and the non-condensable gas generated from the cooling of syngas in the condenser are respectively sent to the coke incinerator for incineration to produce slag and flue gas. A heating surface is arranged inside the coke incinerator, and low-temperature high-pressure feed water flows through the heating surface inside the coke incinerator to absorb the heat generated by the combustion of coke, evaporation gas, and non-condensable gas, generating high-temperature high-pressure steam, which is sent back to the molten salt-heated oil sludge pyrolyzer.

[0011] The beneficial effects of the present invention are as follows:

[0012] The present invention uses fluctuating green electricity as an energy source and heat transfer oil as a heat transfer medium to provide heat for the process of water absorbing heat to generate medium-temperature high-pressure steam and the process of wet oil sludge absorbing heat to generate dry oil sludge at the same time. Molten salt is used as a heat transfer medium to provide heat for the process of medium-temperature high-pressure steam absorbing heat to generate high-temperature high-pressure steam and the process of dry oil sludge absorbing heat to pyrolyze to produce oil sludge pyrolysis products at the same time. The steam huff and puff process and the oil sludge solid waste disposal process are completely synchronized, thus forming the parallel coupling.

[0013] The present invention fully consumes green power resources, ensuring the balance and stability of the power grid; reducing the large amount of fossil energy consumption caused by traditional steam huff and puff and oil sludge disposal processes; using the coupling process of steam huff and puff and oil sludge disposal can achieve the effect of treating oil sludge immediately upon generation, reducing the storage and transportation costs of oil sludge solid waste; respectively selecting heat transfer oil and molten salt as energy storage media, while overcoming the technical problems of high-temperature decomposition of heat transfer oil and low-temperature solidification of molten salt, ensuring the stable operation of the coupling process. Description of the Drawings

[0014] Figure 1Schematic structural diagram of a process system for parallel coupling of green electricity energy storage, oilfield steam stimulation, and solid waste disposal; where 1 represents a heat transfer oil heat exchanger, 2 represents a heat transfer oil electric heater, 3 represents a heat transfer oil storage tank, 4 represents a molten salt heat exchanger, 5 represents an oily sludge drying device, 6 represents a low-temperature salt tank, 7 represents a molten salt electric heater, 8 represents a high-temperature salt tank, 9 represents a molten salt heat supply oily sludge pyrolyzer, 10 represents a condenser, and 11 represents a coke incinerator. Specific Embodiments

[0015] The technical solution of the present invention is not limited to the specific embodiments listed below, and also includes any combination between the specific embodiments. Figure 1 The following specific embodiments are described.

[0016] Specific Embodiment 1: The process system for parallel coupling of green electricity energy storage, oilfield steam stimulation, and solid waste disposal in this embodiment includes a primary steam system, a secondary steam system, a molten salt system, a primary oily sludge treatment system, and a secondary oily sludge treatment system.

[0017] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the primary steam system includes a heat transfer oil heat exchanger 1, a heat transfer oil electric heater 2, and a heat transfer oil storage tank 3, using heat transfer oil as a heat exchange medium to heat low-temperature and high-pressure feed water into medium-temperature and high-pressure superheated steam. Others are the same as Specific Embodiment 1.

[0018] Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 is that the secondary steam system includes a molten salt heat exchanger 4, using high-temperature molten salt as a heat exchange medium to heat medium-temperature and high-pressure superheated steam into high-temperature and high-pressure superheated steam as the steam for the steam stimulation process. Others are the same as Specific Embodiment 1.

[0019] Specific Embodiment 4: The difference between this embodiment and Specific Embodiment 1 is that the molten salt system includes a low-temperature salt tank 6, a molten salt electric heater 7, and a high-temperature salt tank 8, using green electricity as an energy source to heat low-temperature molten salt into high-temperature molten salt. Others are the same as Specific Embodiment 1.

[0020] Specific Embodiment 5: The difference between this embodiment and Specific Embodiment 1 is that the primary oily sludge treatment system includes an oily sludge drying device 5, using high-temperature heat transfer oil as a heat exchange medium to dry wet oily sludge into dry oily sludge and generate evaporation gas at the same time. Others are the same as Specific Embodiment 1.

[0021] Specific Embodiment Six: The difference between this embodiment and Specific Embodiment One is that the secondary sludge treatment system includes a molten salt-heated sludge pyrolyzer 9, a condenser 10, and a coke incinerator 11. The high-temperature molten salt stored in the high-temperature salt tank 8 is used as a heat exchange medium and introduced into the molten salt-heated sludge pyrolyzer 9 to pyrolyze the dry sludge to produce syngas and coke. Others are the same as Specific Embodiment One.

[0022] Specific Embodiment Seven: The difference between this embodiment and Specific Embodiment Six is that the syngas produced by pyrolyzing the dry sludge in the molten salt-heated sludge pyrolyzer 9 is cooled and separated from oil and water in the condenser 10 to generate condensed water, pyrolysis oil, and non-condensable gas. Others are the same as Specific Embodiment Six.

[0023] Specific Embodiment Eight: The difference between this embodiment and Specific Embodiment Seven is that the coke produced by pyrolyzing the dry sludge in the molten salt-heated sludge pyrolyzer 9, the evaporation gas produced by drying the wet sludge in the sludge drying device 5, and the non-condensable gas produced by cooling the syngas in the condenser 10 are respectively sent to the coke incinerator 11 for incineration to produce slag and flue gas. Others are the same as Specific Embodiment Seven.

[0024] Specific Embodiment Nine: The difference between this embodiment and Specific Embodiment Eight is that a heating surface is arranged inside the coke incinerator 11, and the low-temperature high-pressure feed water flows through the heating surface inside the coke incinerator to absorb the heat generated by the combustion of coke, evaporation gas, and non-condensable gas, generating high-temperature high-pressure steam, which is sent back to the molten salt-heated sludge pyrolyzer 9 as a protective carrier gas and part of the heat source for pyrolyzing the dry sludge. Others are the same as Specific Embodiment Eight.

[0025] Specific Embodiment Ten: The difference between this embodiment and Specific Embodiment One is that the process system for coupling green power energy storage in parallel with oilfield steam stimulation and solid waste disposal is specifically operated according to the following steps:

[0026] 1. Start the heat transfer oil electric heater 2 to heat the heat transfer oil to a high temperature state to obtain high-temperature heat transfer oil; the heat transfer oil is heated to 200 - 280 °C;

[0027] 2. Part of the high-temperature heat transfer oil generated in the heat transfer oil electric heater 2 is pumped to the heat transfer oil heat exchanger 1 under the action of a high-pressure oil pump, where it exchanges heat with the preheated high-pressure feed water. While generating medium-temperature high-pressure steam, the high-temperature heat transfer oil is cooled into low-temperature heat transfer oil. The low-temperature heat transfer oil is sent back to the heat transfer oil tank 3 and finally returned to the heat transfer oil electric heater 2 for reheating to complete the heat transfer oil - water cycle; the temperature of the low-temperature heat transfer oil is 100 °C;

[0028] III. Another part of the high-temperature heat-conducting oil generated in the heat-conducting oil electric heater 2 is pumped to the sludge drying device 5 under the action of the high-pressure oil pump, exchanges heat with the wet sludge in the sludge drying device 5, generates dry sludge and evaporation gas, and at the same time, the high-temperature heat-conducting oil is cooled into low-temperature heat-conducting oil. The low-temperature heat-conducting oil is returned to the heat-conducting oil tank 3 and finally returned to the heat-conducting oil electric heater 2 for reheating to complete the heat-conducting oil-wet sludge cycle; the water content of the wet sludge is not higher than 40%; the water content of the dry sludge is not higher than 10%; the temperature of the low-temperature heat-conducting oil is 100 °C;

[0029] IV. The low-temperature molten salt is stored in the low-temperature salt tank 6 and pumped to the molten salt electric heater 7 under the action of the molten salt pump. The low-temperature molten salt in the molten salt electric heater 7 is heated by green electricity to generate high-temperature molten salt. After the high-temperature molten salt flows through the high-temperature salt tank 8, a part of the high-temperature molten salt is sent to the molten salt heat exchanger 4 to exchange heat with the medium-temperature high-pressure steam, generates high-temperature high-pressure superheated steam, and at the same time, the high-temperature molten salt is cooled into low-temperature molten salt. The low-temperature molten salt is returned to the low-temperature salt tank 6 to complete the molten salt-steam cycle, and the generated high-temperature high-pressure superheated steam is used as the steam for the steam stimulation process; another part of the high-temperature molten salt is sent to the molten salt-heated oil sludge pyrolyzer 9 to exchange heat with the dry sludge, generates various oil sludge pyrolysis products, and at the same time, the high-temperature molten salt is cooled into low-temperature molten salt. The low-temperature molten salt is returned to the low-temperature salt tank 6 to complete the molten salt-dry sludge cycle; the temperature of the low-temperature molten salt is 200 °C, and the temperature of the high-temperature molten salt is 540-580 °C; the temperature of the high-temperature high-pressure superheated steam is 540 °C;

[0030] V. After the dry sludge exchanges heat with the high-temperature molten salt in the molten salt-heated oil sludge pyrolyzer 9, syngas and coke are generated;

[0031] VI. The syngas is introduced into the condenser 10 through the heat-insulating pipeline. The water vapor and oil gas in the syngas are liquefied into condensed water and pyrolysis oil, and separated in the oil-water separator in the condenser 10. The separated condensed water is recycled as the heat exchange medium for the subsequent condenser, and the pyrolysis oil is collected and recycled as petroleum resources; at the same time, the syngas is cooled to generate the unliquefied part of the gas, that is, the non-condensable gas;

[0032] VII. The evaporation gas, coke and non-condensable gas are sent to the coke incinerator 11 for incineration; the coke incinerator 11 is internally provided with a water-cooled heating surface. The preheated high-pressure feed water is introduced into the water-cooled heating surface to take away the heat generated by combustion and generate high-temperature high-pressure steam. The high-temperature high-pressure steam is sent to the molten salt-heated oil sludge pyrolyzer 9 as the protective gas for oil sludge pyrolysis and provides part of the heat; the slag and flue gas generated by fuel combustion are safely discharged. The rest is the same as in the first specific embodiment.

[0033] In the primary steam system, green electricity is used as the heating heat source, and heat-conducting oil is used as the heat transfer medium to generate primary steam with medium temperature and high pressure. The primary steam is in a saturated state or a superheated state, and the temperature of the primary steam does not exceed the maximum value of the conventional operating temperature range of the heat-conducting oil. The heat-conducting oil tank is used to store high-temperature heat-conducting oil, and at the same time, electric heating tapes and thermal insulation materials are externally configured to prevent the heat-conducting oil from cooling down.

[0034] In the secondary steam system, molten salt is used as the heat-conducting medium to generate secondary steam that meets the parameter requirements of the steam huff and puff process. The secondary steam is high-temperature, high-pressure superheated steam, and the temperature of the secondary steam does not exceed the maximum value of the conventional operating temperature range of the molten salt.

[0035] In the molten salt system, the low-temperature molten salt in the low-temperature salt tank is sent into the molten salt electric heater through a molten salt pump. The electric energy of green electricity is converted into the heat energy of the molten salt itself through the molten salt electric heater, and the low-temperature molten salt is heated to high-temperature molten salt. The high-temperature salt tank sends the high-temperature molten salt heated and exchanged in the molten salt electric heater into the molten salt heat exchanger and the molten salt heat supply oil sludge pyrolyzer through a molten salt pump. The high-temperature molten salt is cooled into low-temperature molten salt therein, and the low-temperature molten salt continues to be sent into the low-temperature salt tank for storage, completing the molten salt heat exchange cycle.

[0036] In the primary oil sludge treatment system, the oil sludge drying device uses the heat of high-temperature heat-conducting oil to dry the wet oil sludge into dry oil sludge. The high-temperature heat-conducting oil is cooled into low-temperature heat-conducting oil and sent back to the heat-conducting oil tank. After the wet oil sludge is dried, evaporation gas composed of water vapor and short-chain petroleum hydrocarbons is volatilized.

[0037] In the secondary oil sludge treatment system, a heat exchange process occurs in the molten salt heat supply oil sludge pyrolyzer. The dry oil sludge absorbs the heat energy of the high-temperature molten salt and undergoes thermal decomposition to produce syngas and coke. The syngas is introduced into the cooler and separated into condensed water, pyrolysis oil, and non-condensable gas. The coke, non-condensable gas, and evaporation gas are sent into the coke incinerator as combustion fuels to generate harmless flue gas and slag. Water-cooled heating surfaces are arranged in the coke incinerator, and water absorbs heat in the heating surfaces to generate high-temperature, high-pressure steam, which is sent into the molten salt heat supply oil sludge pyrolyzer as the carrier gas and part of the heat source for the dry oil sludge pyrolysis.

[0038] Before the low-temperature, high-pressure water is sent into the heat-conducting oil heat exchanger and the coke incinerator, the heat of the flue gas discharged from the coke incinerator can be used for preheating, that is, a economizer is arranged in the flue gas exhaust duct of the coke incinerator to improve the energy utilization rate.

[0039] All the above equipment is equipped with a thermal insulation layer to avoid energy loss.

[0040] A heating layer is arranged between the tank bodies of the heat-conducting oil tank, the low-temperature salt tank, and the high-temperature salt tank and the thermal insulation layer. The heating layer uses a stable power supply connected to the power grid to perform appropriate heating when the green electricity supply stops or the power is low, ensuring that the heat-conducting oil and the molten salt are at a reasonable operating temperature.

[0041] If the coke incinerator generates too much high-temperature and high-pressure steam, part of the high-temperature and high-pressure steam can be led out and used as the steam required for the oilfield steam stimulation process and injected into the oil well.

[0042] The coke incinerator is equipped with a conventional fuel oil burner. When the coke incinerator is started or when the heat generated by the combustion of coke, non-condensable gas, and evaporation gas is insufficient, pyrolysis oil or self-provided diesel can be used as fuel and fed into the conventional fuel oil burner for combustion to make up for the heat.

[0043] Examples: The beneficial effects of the present invention are verified through the following examples:

[0044] The process system for coupling oilfield steam stimulation and solid waste disposal using green power energy storage in parallel is specifically operated according to the following steps:

[0045] I. Start the heat transfer oil electric heater 2 and heat the heat transfer oil to a high temperature state to obtain high-temperature heat transfer oil; the heat transfer oil is heated to 200 - 280 °C;

[0046] II. Part of the high-temperature heat transfer oil generated in the heat transfer oil electric heater 2 is pumped to the heat transfer oil heat exchanger 1 under the action of a high-pressure oil pump, where it exchanges heat with the preheated high-pressure feed water. While generating medium-temperature and high-pressure steam, the high-temperature heat transfer oil is cooled into low-temperature heat transfer oil. The low-temperature heat transfer oil is sent back to the heat transfer oil tank 3 and finally returned to the heat transfer oil electric heater 2 for reheating to complete the heat transfer oil - water cycle; the temperature of the low-temperature heat transfer oil is 100 °C;

[0047] III. Another part of the high-temperature heat transfer oil generated in the heat transfer oil electric heater 2 is pumped to the oily sludge drying device 5 under the action of a high-pressure oil pump, where it exchanges heat with the wet oily sludge. While generating dry oily sludge and evaporation gas, the high-temperature heat transfer oil is cooled into low-temperature heat transfer oil. The low-temperature heat transfer oil is sent back to the heat transfer oil tank 3 and finally returned to the heat transfer oil electric heater 2 for reheating to complete the heat transfer oil - wet oily sludge cycle; the water content of the wet oily sludge is not higher than 40%; the water content of the dry oily sludge is not higher than 10%; the temperature of the low-temperature heat transfer oil is 100 °C;

[0048] IV. The low-temperature molten salt is stored in the low-temperature salt tank 6 and pumped to the molten salt electric heater 7 under the action of the molten salt pump. The low-temperature molten salt in the molten salt electric heater 7 is heated by green electricity to generate high-temperature molten salt. After the high-temperature molten salt flows through the high-temperature salt tank 8, a part of the high-temperature molten salt is sent to the molten salt heat exchanger 4 to exchange heat with the medium-temperature high-pressure steam, generating high-temperature high-pressure superheated steam while the high-temperature molten salt is cooled into low-temperature molten salt, and the low-temperature molten salt is sent back to the low-temperature salt tank 6 to complete the molten salt-steam cycle. The generated high-temperature high-pressure superheated steam is used as the steam for the steam huff and puff process; another part of the high-temperature molten salt is sent to the molten salt heat supply oil sludge pyrolyzer 9 to exchange heat with the dry oil sludge, generating various oil sludge pyrolysis products while the high-temperature molten salt is cooled into low-temperature molten salt, and the low-temperature molten salt is sent back to the low-temperature salt tank 6 to complete the molten salt-dry oil sludge cycle; the temperature of the low-temperature molten salt is 200 °C, and the temperature of the high-temperature molten salt is 540-580 °C; the temperature of the high-temperature high-pressure superheated steam is 540 °C;

[0049] V. After the dry oil sludge exchanges heat with the high-temperature molten salt in the molten salt heat supply oil sludge pyrolyzer 9, syngas and coke are produced;

[0050] VI. The syngas is introduced into the condenser 10 through the heat-insulating pipeline. The water vapor and oil gas in the syngas are liquefied into condensed water and pyrolysis oil, and are separated in the oil-water separator in the condenser 10. The separated condensed water is recovered as the heat exchange medium for the subsequent condenser, and the pyrolysis oil is collected and recovered as petroleum resources; at the same time, the syngas is cooled to produce the unliquefied part of the gas, that is, the non-condensable gas;

[0051] VII. The evaporation gas, coke and non-condensable gas are sent to the coke incinerator 11 for incineration; the coke incinerator 11 is internally provided with a water-cooled heating surface. The high-pressure feed water after preheating is introduced into the water-cooled heating surface to take away the heat generated by combustion, generating high-temperature high-pressure steam. The high-temperature high-pressure steam is sent to the molten salt heat supply oil sludge pyrolyzer 9 as the protective gas for oil sludge pyrolysis and provides part of the heat; the slag and flue gas generated by fuel combustion are safely discharged.

[0052] This embodiment fully consumes green power resources, ensuring the balance and stability of the power grid; reducing the large amount of fossil energy consumption caused by traditional steam huff and puff and oil sludge disposal processes; using the coupling process of steam huff and puff and oil sludge disposal, the effect of treating oil sludge as soon as it is generated can be achieved, reducing the storage and transportation costs of oil sludge solid waste; respectively selecting heat transfer oil and molten salt as energy storage media, while overcoming the technical problems of high-temperature decomposition of heat transfer oil and low-temperature solidification of molten salt, ensuring the stable operation of the coupling process.

Claims

1. A process system for parallel coupling of green power energy storage with oilfield steam stimulation and solid waste disposal, characterized in that The process system for coupling oilfield steam stimulation and solid waste disposal by using green power energy storage in parallel includes a primary steam system, a secondary steam system, a molten salt system, a primary oil sludge treatment system, and a secondary oil sludge treatment system; the primary steam system includes a heat transfer oil heat exchanger (1), a heat transfer oil electric heater (2), and a heat transfer oil storage tank (3), using heat transfer oil as the heat exchange medium to heat low-temperature and high-pressure feed water into medium-temperature and high-pressure superheated steam; The secondary steam system includes a molten salt heat exchanger (4), using high-temperature molten salt as the heat exchange medium to heat medium-temperature and high-pressure superheated steam into high-temperature and high-pressure superheated steam, which is used as the steam for the steam stimulation process; The molten salt system includes a low-temperature salt tank (6), a molten salt electric heater (7), and a high-temperature salt tank (8), using green power as the energy source to heat low-temperature molten salt into high-temperature molten salt; The primary oil sludge treatment system includes an oil sludge drying device (5), using high-temperature heat transfer oil as the heat exchange medium to dry wet oil sludge into dry oil sludge and generate evaporation gas at the same time; The secondary oil sludge treatment system includes a molten salt-heated oil sludge pyrolyzer (9), a condenser (10), and a coke incinerator (11). Using the high-temperature molten salt stored in the high-temperature salt tank (8) as the heat exchange medium and introducing it into the molten salt-heated oil sludge pyrolyzer (9), dry oil sludge is pyrolyzed to produce syngas and coke; the syngas generated from the pyrolysis of dry oil sludge in the molten salt-heated oil sludge pyrolyzer (9) is cooled and separated from oil and water in the condenser (10) to generate condensed water, pyrolysis oil, and non-condensable gas; the coke generated from the pyrolysis of dry oil sludge in the molten salt-heated oil sludge pyrolyzer (9), the evaporation gas generated from the drying of wet oil sludge in the oil sludge drying device (5), and the non-condensable gas generated from the cooling of syngas in the condenser (10) are respectively sent to the coke incinerator (11) for incineration to produce slag and flue gas; a heating surface is arranged inside the coke incinerator (11), and low-temperature and high-pressure feed water flows through the heating surface inside the coke incinerator to absorb the heat generated by the combustion of coke, evaporation gas, and non-condensable gas, generating high-temperature and high-pressure steam, which is sent back to the molten salt-heated oil sludge pyrolyzer (9).

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