Oil sludge treatment method and system

Abstract

The present invention belongs to the fields of oil field, petrochemical industry, and hazardous waste environmental protection technology, and specifically relates to a sludge treatment method and system. The sludge treatment method provided by the present invention comprises the following steps: 1) spraying superheated steam to the sludge added with carbonaceous additives to obtain a mixture of oil, water vapor and residue; 2) performing gas-solid separation on the mixture of oil, water vapor and residue obtained in step 1) to obtain oil, water vapor and residue, and performing liquid-liquid separation on the oil, water vapor to obtain oil and water. The sludge treatment method provided by the present invention effectively realizes the reduction treatment of sludge, and at the same time, the residue can be rendered harmless without causing secondary pollution.

Description

Technical Field

[0001] The invention belongs to the technical fields of oil field, petrochemical industry and hazardous waste environmental protection, and specifically relates to an oil sludge treatment method and system. Background Art

[0002] A large amount of sludge is produced in the process of crude oil extraction, refining, storage, etc. Its characteristics are that it contains a variety of toxic and harmful substances, has a high water content, small solid particles, serious oil-water emulsification, and is difficult to dehydrate. Its disposal has always been a major problem for oil fields and petrochemical companies. In 2008, the state revised the list of hazardous wastes and classified oily sludge (i.e., sludge) as hazardous waste. Sludge treatment has become a major concern of environmental protection departments at all levels. With the increasingly stringent national environmental protection laws and regulations, the enhancement of public environmental awareness, and the increase in environmental law enforcement, the harmless disposal of sludge will be another environmental protection requirement for petrochemical companies after sewage treatment and waste gas treatment. Therefore, the economic and harmless treatment of oily sludge is imminent.

[0003] Prior art CN201648205U discloses a combined device for drying oilfield sludge, which at least includes a sludge hopper, a screw conveyor, a paddle dryer, a cyclone separator and an oil-water separator. The lower end of the sludge hopper is connected to the screw conveyor; the hollow shaft of the paddle dryer and the hollow blades on the shaft and the honeycomb jacket are connected to the high-temperature heating medium. When the above device treats sludge, the water and oil in the sludge are evaporated at a low temperature of about 160°C through the paddle dryer. The steam and the sludge are in indirect contact, with low thermal efficiency and long reaction time.

[0004] Prior art CN108624347A discloses a method for synchronous recovery and purification of oil products in sludge, which includes an oil sludge adding process, a steam preparation process, a steam injection process, an oil-water separation process, a condensation separation process, a condensate desalting and reinjection process, and an oil sludge residue incineration and heating process. However, the steam injection amount used in the above method is 3-6 times the amount of oil sludge treatment, the steam usage is large, the energy consumption is high, and there are problems such as incomplete oil sludge separation and high oil content in the residue. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is the problem of incomplete sludge separation and high oil content in the residue in the existing sludge separation method, and thus a sludge treatment method and system are proposed.

[0006] To this end, the technical solution adopted in this application is:

[0007] A method for treating oily sludge comprises the following steps:

[0008] 1) Spraying superheated steam to the oil sludge added with carbonaceous additives to obtain a mixture of oil, water vapor and residue;

[0009] 2) subjecting the mixture of oil, water vapor and residue obtained in step 1) to gas-solid separation to obtain oil, water vapor and residue, and subjecting the oil, water vapor to liquid-liquid separation to obtain oil and water.

[0010] Furthermore, before spraying superheated steam onto the oil sludge added with the carbonaceous additive, the method further includes a step of dehydrating the oil sludge added with the carbonaceous additive.

[0011] Furthermore, the step of dehydrating the oil sludge to which the carbonaceous additive is added comprises:

[0012] a) adding a demulsifier, a flocculant and a carbon additive to the oil sludge in sequence to obtain pretreated oil sludge;

[0013] b) dehydrating the pretreated sludge obtained in step a).

[0014] Furthermore, step b) further includes the step of low-temperature drying and dehydrating the dehydrated oil sludge;

[0015] The low temperature drying temperature is 50-75°C.

[0016] Furthermore, the specific steps of step a) are: adding a demulsifier to the oil sludge, stirring, letting it stand, then adding a flocculant and a carbon additive, continuing to stir, letting it stand again, to obtain pretreated oil sludge.

[0017] Furthermore, the stirring temperature is 40-70° C., the standing time is 10-60 min, and the second standing time is 1-3 h.

[0018] Furthermore, in step b), the moisture content of the dehydrated sludge is 60-80%.

[0019] Furthermore, after the dehydrated oil sludge is subjected to low temperature drying and dehydration, its water content is 30-40%.

[0020] Furthermore, the carbonaceous additive is selected from one or more of coke, sawdust, carbon black, wood chips, straw, and rice straw;

[0021] The amount of the carbon additive is 1-5% of the weight of the sludge.

[0022] Furthermore, in step 2), before the oil-water vapor is subjected to liquid-liquid separation, a step of exchanging heat between the oil-water vapor and the oil-water vapor is also included.

[0023] Furthermore, in step a), before adding the demulsifier to the oil sludge, the step of filtering and screening the oil sludge is also included;

[0024] After filtering and screening the oil sludge, the particle size of the oil sludge is less than 1 mm.

[0025] Further, the demulsifier is used in an amount of 0.01-0.1% by weight of the sludge;

[0026] The amount of the flocculant is 0.01-0.1% of the weight of the sludge;

[0027] The superheated steam temperature is 400-700°C.

[0028] Furthermore, in the present invention, the process of spraying superheated steam onto the oil sludge added with carbonaceous additives is carried out in a thermal sensing chamber, and the mass ratio of the superheated steam to the oil sludge entering the thermal sensing chamber is 0.5-2:1.

[0029] Furthermore, the demulsifier is selected from one or more of nonionic surfactants, electrolytes, cationic surfactants, and anionic surfactants;

[0030] The flocculant is selected from one or more of polyacrylamide organic polymers, polyacrylic acid organic polymers, and inorganic polymers.

[0031] Further, the electrolyte is selected from one or more of hydrochloric acid, sodium chloride, magnesium chloride, calcium chloride, and aluminum nitrate;

[0032] The inorganic polymer is selected from one or more of polyaluminium chloride, polyaluminium sulfate, polyferric chloride and polyferric sulfate.

[0033] The present invention also provides an oil sludge treatment system, comprising a screening device, a demulsifier, a flocculation device, a dehydration device, a thermal sensing device, a cyclone separation device, and a cooling oil-water separation device, which are sequentially connected through an oil sludge conveying pipeline; wherein the demulsifier is also provided with a demulsifier feed port, the flocculation device is also provided with an additive feed port, the dehydration device is also provided with a wastewater discharge port, and the thermal sensing device is also provided with a superheated steam inlet.

[0034] Furthermore, a low-temperature drying device is provided between the dehydration device and the thermal sensing device, and is respectively connected to the dehydration device and the thermal sensing device through an oil sludge conveying pipeline.

[0035] Furthermore, a heat exchange device is provided between the cyclone separation device and the cooling oil-water separation device, and is connected to the cyclone separation device and the cooling oil-water separation device respectively through an oil-water conveying pipeline.

[0036] Furthermore, the low-temperature drying device is also connected to the heat exchange device through a hot air delivery pipeline, and the heat exchange device is also provided with a cold air inlet.

[0037] Furthermore, it also includes:

[0038] A superheated steam generating device connected to the superheated steam inlet of the thermal sensing device through a superheated steam pipeline;

[0039] The demulsifier storage bin is connected to the demulsifier inlet of the demulsifier device through a demulsifier delivery pipeline.

[0040] Furthermore, the additive feed inlet includes a flocculant feed inlet and a carbonaceous additive feed inlet.

[0041] Furthermore, it also includes:

[0042] A flocculant storage bin connected to a flocculant inlet of the flocculation device via a flocculant delivery pipeline;

[0043] The carbonaceous additive storage bin is connected to the carbonaceous additive inlet of the flocculation device through a carbonaceous additive delivery pipeline.

[0044] Furthermore, it also includes:

[0045] An oil-water collecting device connected to the dehydrating device via an oil-water conveying pipeline;

[0046] The residue bin is connected to the cyclone separation device through a residue conveying pipeline.

[0047] Furthermore, it also includes:

[0048] An oil storage tank connected to the cooling oil-water separation device through an oil pipeline;

[0049] The sewage treatment device is connected to the cooling oil-water separation device through a sewage conveying pipeline.

[0050] The technical solution of the present invention has the following advantages:

[0051] 1. The oil sludge treatment method provided by the present invention sprays superheated steam to the oil sludge added with carbonaceous additives, and then performs gas-solid separation on the obtained mixture of oil-water vapor and residue, and performs liquid-liquid separation on the obtained oil-water vapor to obtain oil and water. The addition of the carbonaceous additive of the present invention can not only increase the flocculation effect of the oil sludge, but also, after entering the thermal sensing chamber, the carbonaceous additive adsorbs oil and water to disperse the oil and water, accelerates the volatilization of oil and water in the oil sludge, improves the oil-water separation efficiency, and effectively reduces the oil content in the residue. At the same time, due to the adsorption effect of the carbonaceous material, the heavy metal elements in the oil sludge can be effectively fixed in the residue, thereby improving the quality of the recovered oil.

[0052] 2. The oil sludge treatment method provided by the present invention further includes the step of dehydrating the oil sludge added with the carbonaceous additive before spraying superheated steam onto the oil sludge added with the carbonaceous additive. The present invention obtains pretreated oil sludge by sequentially adding a demulsifier, a flocculant and a carbonaceous additive into the oil sludge; then the pretreated oil sludge is dehydrated, which greatly reduces the water content of the oil sludge, making it more conducive to oil sludge separation. Combined with the step of spraying superheated steam onto the oil sludge, several steps cooperate with each other to effectively achieve the reduction of the oil sludge, which can be reduced by 80-95%. At the same time, the residue can be harmless, the oil content of the residue is less than 3‰, and the water content is less than 10%, which effectively solves the problem of incomplete oil sludge separation. At the same time, the method of the present invention uses superheated steam as the injection heat source, which greatly reduces the amount of steam used and does not cause secondary pollution.

[0053] 3. The oil sludge treatment method provided by the present invention further includes the step of subjecting the dehydrated oil sludge to low-temperature drying and dehydration, wherein the low-temperature drying temperature is 50-75° C. The present invention reduces the water content of the oil sludge to 30-40% by subjecting the oil sludge to low-temperature drying and dehydration at a specific temperature, making it more conducive to oil sludge separation, further reducing the oil content of the residue, and greatly reducing the use of superheated steam in subsequent processes, thereby reducing energy consumption.

[0054] 4. In the oil sludge treatment method provided by the present invention, further, the carbonaceous additive is selected from one or more of coke, sawdust, carbon black, wood chips, straw, and rice straw; the amount of the carbonaceous additive is 1-5% of the weight of the oil sludge. The inventor has found through research that the carbonaceous additive can further reduce the oil content in the residue under the conditions of the above specific type and specific amount.

[0055] 5. The oil sludge treatment method provided by the present invention further includes a step of exchanging heat for the oil-water vapor before the oil-water vapor is subjected to liquid-liquid separation. The present invention transports the oil-water vapor separated from the cyclone separation device to the heat exchange device, preheats the cold air in the heat exchange device, and obtains high-temperature hot air, which enters the low-temperature drying device to continue to perform low-temperature drying and dehydration on the dehydrated oil sludge. At the same time, the cold air in the heat exchange device is used to cool the oil-water vapor, which greatly reduces the energy consumption of the system.

[0056] 6. The oil sludge treatment method provided by the present invention further comprises the step of filtering and screening the oil sludge before adding the demulsifier. Furthermore, after filtering and screening the oil sludge, the particle size of the oil sludge is less than 1 mm. The inventor has found through research that when the oil sludge does not contain impurities larger than 1 mm, the oil content in the residue can be effectively reduced.

[0057] 7. In the oil sludge treatment method provided by the present invention, the demulsifier is used in an amount of 0.01-0.1% of the weight of the oil sludge; the flocculant is used in an amount of 0.01-0.1% of the weight of the oil sludge. Studies have shown that under the above conditions, the oil content of the residue and the amount of superheated steam used can be further reduced.

[0058] 8. The oil sludge treatment system provided by the present invention comprises a screening device, a demulsifier, a flocculation device, a dehydration device, a thermal sensing device, a cyclone separation device, and a cooling oil-water separation device, which are sequentially connected through an oil sludge conveying pipeline; wherein the demulsifier is also provided with a demulsifier feed port, the flocculation device is also provided with an additive feed port, the dehydration device is also provided with a wastewater discharge port, and the thermal sensing device is also provided with a superheated steam inlet. In the present invention, the oil sludge is sequentially treated through a screening device, a demulsifier, a flocculation device, a dehydration device, a thermal sensing device, a cyclone separation device, and a cooling oil-water separation device, which can effectively solve the problem of incomplete oil sludge separation, and can effectively reduce the amount of oil sludge, which can be reduced by 80-95%, and the residue can be harmless. The oil sludge treated by this system has a residue oil content of less than 3‰ and a water content of less than 10%, thereby avoiding the problem of secondary pollution during the oil sludge treatment process.

[0059] Furthermore, a low-temperature drying device is provided between the dehydration device and the thermal sensing device, and is connected to the dehydration device and the thermal sensing device respectively through an oil sludge conveying pipeline. A heat exchange device is provided between the cyclone separation device and the cooling oil-water separation device, and is connected to the cyclone separation device and the cooling oil-water separation device respectively through an oil-water conveying pipeline. The low-temperature drying device is also connected to the heat exchange device through a hot air conveying pipeline, and the heat exchange device is also provided with a cold air inlet. Through the above-mentioned arrangement, the dehydrated sludge is conveyed from the dehydration device to the low-temperature drying device, and in the low-temperature drying device, the dehydrated sludge is subjected to low-temperature drying and dehydration by hot air, and then the secondary dehydrated sludge is conveyed to the thermal sensing device (thermal sensing chamber). After the dehydrated sludge is subjected to low-temperature drying treatment, the water content of the sludge is reduced to 30-40%, making it more conducive to sludge separation and further reducing the oil content of the residue. A heat exchange device is provided between the cyclone separation device and the cooling oil-water separation device. The oil-water vapor is separated from the cyclone separation device and transported to the heat exchange device. The cold air in the heat exchange device is preheated to obtain high-temperature hot air. The high-temperature hot air enters the low-temperature drying device to continue to perform low-temperature drying and dehydration on the dehydrated oil sludge. At the same time, the cold air in the heat exchange device is used to cool the oil-water vapor, which greatly reduces the energy consumption of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0061] Figure 1 is a process flow chart of the oil sludge treatment method in Example 4 of the present invention;

[0062] Figure 2 is a process flow chart of the oil sludge treatment method in Example 5 of the present invention;

[0063] Figure 3 is a flow chart of the oil sludge treatment system of the present invention in which the oil sludge is not subjected to low temperature drying treatment;

[0064] Figure 4 is a flow chart of an oil sludge treatment system for performing low temperature drying treatment on oil sludge according to the present invention;

[0065] The reference numerals are as follows:

[0066] 1. Screening device; 2. Demulsifier; 3. Flocculation device; 4. Dehydration device; 5. Thermal sensing device; 6. Cyclone separation device; 7. Cooling oil-water separation device; 8. Residue bin; 9. Superheated steam generating device; 10. Oil-water collecting device; 11. Low-temperature drying device; 12. Heat exchange device; 13. Sludge storage device; 14. Demulsifier storage bin; 15. Flocculant storage bin; 16. Carbon additive storage bin. DETAILED DESCRIPTION

[0067] The technical solution of the present invention is described clearly and completely below. 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.

[0068] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0069] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0071] Example 1

[0072] like Figure 3 As shown, this embodiment provides an oil sludge treatment system, comprising a screening device 1, a demulsifier 2, a flocculation device 3, a dehydration device 4, a thermal sensing device 5, a cyclone separation device 6, and a cooling oil-water separation device 7, which are sequentially connected through an oil sludge conveying pipeline; wherein the demulsifier 2 is also provided with a demulsifier feed port, the flocculation device 3 is also provided with an additive feed port, the dehydration device 4 is also provided with a wastewater discharge port, and the thermal sensing device 5 is also provided with a superheated steam inlet.

[0073] In the present invention, the oil sludge is processed in sequence through a screening device 1, a demulsifying device 2, a flocculation device 3, a dehydration device 4, a thermal sensing device 5, a cyclone separation device 6, and a cooling oil-water separation device 7, which can effectively solve the problem of incomplete separation of the oil sludge, can effectively reduce the amount of the oil sludge, and at the same time, the residue can be rendered harmless. The oil content of the residue of the oil sludge treated by this system is less than 3‰, and the water content is less than 10%, thereby avoiding the problem of secondary pollution in the process of oil sludge treatment.

[0074] In a specific embodiment of the present invention, it also includes a superheated steam generating device 9, which is connected to the superheated steam inlet of the thermal sensing device 5 through a superheated steam pipeline; a demulsifier storage bin 14, which is connected to the demulsifier feed port of the demulsifier device 2 through a demulsifier delivery pipeline; and the additive feed port includes a flocculant feed port and a carbonaceous additive feed port. It also includes a flocculant storage bin 15, which is connected to the flocculant feed port of the flocculation device 3 through a flocculant delivery pipeline; a carbonaceous additive storage bin 16, which is connected to the carbonaceous additive feed port of the flocculation device 3 through a carbonaceous additive delivery pipeline; and an oil-water collecting device 10, which is connected to the dehydration device 4 through an oil-water delivery pipeline; a residue bin 8, which is connected to the cyclone separation device 6 through a residue delivery pipeline; an oil storage tank, which is connected to the cooling oil-water separation device 7 through an oil delivery pipeline; and a sewage treatment device, which is connected to the cooling oil-water separation device 7 through a sewage delivery pipeline.

[0075] In a specific embodiment of the present invention, Figure 4 As shown, a low-temperature drying device 11 is provided between the dehydration device 4 and the thermal sensing device 5, and is connected to the dehydration device 4 and the thermal sensing device 5 respectively through an oil sludge conveying pipeline. A heat exchange device 12 is provided between the cyclone separation device 6 and the cooling oil-water separation device 7, and is connected to the cyclone separation device 6 and the cooling oil-water separation device 7 respectively through an oil-water conveying pipeline. The low-temperature drying device 11 is also connected to the heat exchange device 12 through a hot air conveying pipeline, and the heat exchange device 12 is also provided with a cold air inlet. Through the above arrangement, the dehydrated sludge is conveyed from the dehydration device 4 to the low-temperature drying device 11, and in the low-temperature drying device 11, the dehydrated sludge is subjected to low-temperature drying and dehydration by hot air, and then the secondary dehydrated sludge is conveyed to the thermal sensing device 5 (thermal sensing chamber). After the dehydrated sludge is subjected to low-temperature drying treatment, the water content of the sludge is reduced to 30-40%, making it more conducive to sludge separation and further reducing the oil content of the residue. A heat exchange device 12 is provided between the cyclone separation device 6 and the cooling oil-water separation device 7. Optionally, the heat exchange device 12 may be a heat exchanger. The oil-water vapor is separated from the cyclone separation device 6 and transported to the heat exchange device 12. The cold air in the heat exchange device 12 is preheated to obtain high-temperature hot air. The high-temperature hot air enters the low-temperature drying device 11 to continue to perform low-temperature drying and dehydration on the dehydrated oil sludge. At the same time, the heat of the oil-water vapor is used to preheat the cold air, which effectively utilizes the heat of the system and greatly reduces the energy consumption of the system.

[0076] In a specific embodiment of the present invention, the screening device 1 has a feed port, a first discharge port and a second discharge port (for discharging filtered impurities). The feed port is connected to the outlet of the sludge storage device 13 .

[0077] The demulsifier 2 has a first feed inlet, a second feed inlet (demulsifier feed inlet) and a discharge port. The first feed inlet is connected to the first discharge port of the screening device 1, the second feed inlet is connected to the demulsifier storage bin 14, and the discharge port is connected to the first feed inlet of the flocculation device 3.

[0078] The flocculation device 3 has a first feed port, a second feed port (flocculant feed port), a third feed port (carbonaceous additive feed port) and a discharge port. The second feed port is connected to the flocculant storage bin 15, the third feed port is connected to the carbonaceous additive storage bin 16, and the discharge port is connected to the inlet of the dehydration device 4.

[0079] The dehydration device 4 has an inlet, a first outlet and a second outlet (wastewater outlet). The first outlet is connected to the first inlet of the thermal sensing device 5, and the second outlet is connected to the oil-water collecting device 10.

[0080] The thermal sensing device 5 has a first inlet, a second inlet (superheated steam inlet) and an outlet. The second inlet is connected to the outlet of the superheated steam generating device 9, and the outlet is connected to the inlet of the cyclone separation device 6.

[0081] The cyclone separation device 6 has an inlet, a first outlet and a second outlet. The first outlet is connected to the ash bin, and the second outlet is connected to the inlet of the cooling oil-water separation device 7.

[0082] The cooling oil-water separation device 7 has an inlet, a first outlet and a second outlet. The first outlet is connected to the oil storage tank, and the second outlet is connected to the sewage treatment device.

[0083] The superheated steam generating device 9 has an inlet and an outlet. The inlet is connected to the saturated steam inlet.

[0084] In a specific embodiment of the present invention, the dehydration device 4 has an inlet, a first outlet and a second outlet. The first outlet is connected to the first inlet of the low temperature drying device 11, and the second outlet is connected to the oil-water collecting device 10.

[0085] The drying device has a first inlet, a second inlet and an outlet. The second inlet is connected to the second outlet of the heat exchanger device, and the outlet is connected to the first inlet of the thermal sensing device 5.

[0086] The thermal sensing device 5 has a first inlet, a second inlet and an outlet. The second inlet is connected to the outlet of the superheated steam generating device 9, and the outlet is connected to the inlet of the cyclone separation device 6.

[0087] The cyclone separation device 6 has an inlet, a first outlet and a second outlet. The first outlet is connected to the ash bin, and the second outlet is connected to the first inlet of the heat exchanger device.

[0088] The heat exchanger device has a first inlet, a second inlet (cold air inlet), a first outlet and a second outlet. The second inlet is connected to the cold air port, and the first outlet is connected to the inlet of the cooling oil-water separation device 7.

[0089] The cooling oil-water separation device 7 has an inlet, a first outlet and a second outlet. The first outlet is connected to the oil storage tank, and the second outlet is connected to the sewage treatment device.

[0090] In a specific embodiment of the present invention, the oil sludge is first filtered through a screening device 1. In a specific embodiment of the present invention, the oil sludge is filtered through a 1mm grid to filter out large mechanical impurities ≥1mm, thereby obtaining oil sludge with a particle size of <1mm. The filtered oil sludge is transported to a demulsifier tank (demulsifier device 2), and a demulsifier is added to the demulsifier tank from a demulsifier storage bin 14. The demulsifier tank is provided with a stirring device and a heating temperature control device to fully stir the oil sludge and the demulsifier to mix them evenly, and let them stand after sufficient reaction. In a specific embodiment of the present invention, the amount of the demulsifier is 0.01-0.1% of the weight of the oil sludge, the stirring temperature is 40-70°C, the standing time is 10-60min, and the demulsifier is selected from one or more of non-ionic surfactants, electrolytes, cationic surfactants, and anionic surfactants; the electrolyte is selected from one or more of hydrochloric acid, sodium chloride, magnesium chloride, calcium chloride, and aluminum nitrate. Then the sludge after standing is transported to the flocculation tank (flocculation device 3), and the flocculant and the carbon additive are added to the flocculation tank by the flocculant storage bin 15 and the carbon additive storage bin 16 respectively. The flocculation tank is provided with a stirring device, and the stirring is uniform, and the sludge is allowed to stand again after sufficient reaction to obtain the pretreated sludge. In a specific embodiment of the present invention, the amount of the flocculant is 0.01-0.1% of the weight of the sludge, and the second standing time is 1-3h. The flocculant is selected from one or more of polyacrylamide organic polymers, polyacrylic acid organic polymers, and inorganic polymers. The inorganic polymer is selected from one or more of polyaluminum chloride, polyaluminum sulfate, polyferric chloride, and polyferric sulfate. The carbon additive is selected from one or more of coke, sawdust, carbon black, wood chips, straw, and rice straw; the amount of the carbon additive is 1-5% of the weight of the sludge. The addition of the carbonaceous additive of the present invention can not only increase the flocculation effect of the oil sludge, but also, after entering the thermal sensing device 5, the carbonaceous additive absorbs oil and water to disperse the oil and water, accelerate the volatilization of oil and water in the oil sludge, improve the oil-water separation efficiency, and effectively reduce the oil content in the residue. At the same time, due to the adsorption effect of the carbonaceous material, the heavy metal elements in the oil sludge can be effectively fixed in the residue, thereby improving the quality of the recovered oil.

[0091] The pre-treated sludge is transported to the screw stack (dehydration device 4) for dehydration treatment to obtain an oil-water mixture and dehydrated sludge, and the water content of the dehydrated sludge is 60-80%. Under this water content condition, it is more conducive to the subsequent sludge separation. The oil-water mixture obtained after dehydration is subjected to static separation in the oil-water collecting device 10 to obtain oil and water. The dehydrated sludge is further transported to the thermal sensing chamber (thermal sensing device 5), where the dehydrated sludge collides with the superheated steam entering the thermal sensing chamber, and the water and oil in the sludge evaporate to obtain a mixture of oil-water vapor and residue, which leaves the thermal sensing chamber together and enters the cyclone separator (cyclone separator 6), where the residue is separated, and the oil-water vapor enters the cooling oil-water separator 7 for cooling, and the oil and water are separated by static separation. In a specific embodiment of the present invention, in the thermal sensing chamber, the temperature of the superheated steam is 400-700°C; the mass ratio of the amount of superheated steam to the oil sludge entering the thermal sensing chamber is 0.5-2:1. After extensive research, the inventors found that the specific pretreatment steps of the present invention, especially the addition of a specific type of carbonaceous additives, and the dehydration of the oil sludge to a specific moisture content, can greatly reduce the amount of superheated steam used, which is more conducive to the separation of oil sludge and the reduction of the oil content in the residue.

[0092] In a specific embodiment of the present invention, the pretreated sludge is conveyed to the screw stack (dehydration device 4) for dehydration, and the dehydrated sludge obtained is conveyed to the low-temperature drying device 11. In the low-temperature drying device 11, the dehydrated sludge is subjected to low-temperature drying and dehydration by hot air, and then the secondary dehydrated sludge is conveyed to the thermal sensing chamber (thermal sensing device 5). In the thermal sensing chamber, the secondary dehydrated sludge collides with the superheated steam entering the thermal sensing chamber, and the water and oil in the sludge evaporate to obtain a mixture of oil-water vapor and residue. The mixture of oil-water vapor and residue leaves the thermal sensing chamber together and enters the cyclone separator (cyclone separator 6). In the cyclone separator, the residue is separated, and the oil-water vapor is conveyed to the heat exchanger (heat exchange device 12), and the cold air in the heat exchanger is preheated to obtain high-temperature hot air. The high-temperature hot air enters the low-temperature drying device 11 to continue to perform low-temperature drying and dehydration on the dehydrated sludge. At the same time, the heat of the oil and water vapor is used to preheat the cold air, which effectively utilizes the heat of the system and greatly reduces the energy consumption of the system. The cooled oil and water vapor is transported to the cooling oil-water separation device 7 for further cooling, and the oil and water are separated by standing. In a specific embodiment of the present invention, the low-temperature drying temperature is 50-75°C. After the specific low-temperature drying operation of the present invention, the water content of the oil sludge after secondary dehydration is 30-40%, which greatly improves the oil sludge separation effect and effectively reduces the oil content in the residue.

[0093] Example 2

[0094] This embodiment provides a method for treating oil sludge, wherein the oil sludge is oily sludge after wastewater treatment in a refinery, with a water content of 95%, an oil content of 3%, and a solid content of 2%.

[0095] The steps include:

[0096] 1) Add 0.05% of demulsifier dodecyl sulfonic acid by weight of the sludge to the sludge, heat to 50°C and stir, allow it to react fully and then stand for 20 minutes, then add 0.02% of flocculant PAM by weight of the sludge and 5% of coke powder by weight of the sludge, continue stirring, allow it to react fully and then stand for another 2 hours to obtain pretreated sludge;

[0097] 2) conveying the pretreated sludge obtained in step 1) to a screw press for dehydration to obtain an oil-water mixture and dehydrated sludge, wherein the water content of the dehydrated sludge is 80%;

[0098] 3) passing saturated steam through a superheated steam generator (superheated steam generating device 9) to obtain superheated steam with a temperature of 550°C; conveying the dehydrated sludge to a thermal sensing chamber, the superheated steam is accelerated to Mach 2 through a nozzle in the thermal sensing chamber, and superheated steam is sprayed toward the dehydrated sludge. The superheated steam collides head-on with the sludge, and the oil and water in the sludge are evaporated under high temperature and high speed conditions to obtain a mixture of oil-water vapor and residue.

[0099] 4) The mixture of oil-water vapor and residue obtained in step 3) is separated into residue and oil-water vapor by a cyclone separator, and the oil-water vapor is separated into oil and water by condensation and standing, wherein the separated water enters the sewage treatment system and the oil is directly recycled.

[0100] According to the test, when the method of this embodiment is used to treat the oil sludge, the amount of superheated steam used to treat one ton of oil sludge is 750 kg, the oil content of the residue is 2.1‰, and the water content is 8%.

[0101] Example 3

[0102] This embodiment provides a method for treating oil sludge, wherein the oil sludge is the bottom sludge of a refinery tank, with a water content of 90%, an oil content of 8%, and a solid content of 2%.

[0103] The steps include:

[0104] 1) Adding 0.01% of the weight of the sludge to the demulsifier triethanolamine oleate, heating to 40°C and stirring, allowing it to fully react and then standing for 20 minutes, then adding 0.02% of the weight of the sludge to the flocculant polyaluminium chloride and 1% of the weight of the sludge to the sawdust, continuing to stir, allowing it to fully react and then standing for another 1.5 hours to obtain the pretreated sludge;

[0105] 2) conveying the pretreated sludge obtained in step 1) to a screw press for dehydration to obtain an oil-water mixture and dehydrated sludge, wherein the water content of the dehydrated sludge is 60%;

[0106] 3) passing saturated steam through a superheated steam generator (superheated steam generating device 9) to obtain superheated steam with a temperature of 500° C.; conveying the dehydrated sludge to a thermal sensing chamber, the superheated steam is accelerated to Mach 1.5 through a nozzle in the thermal sensing chamber, and the superheated steam is sprayed toward the dehydrated sludge. The superheated steam collides head-on with the sludge, and the oil and water in the sludge are evaporated under high temperature and high speed conditions to obtain a mixture of oil-water vapor and residue.

[0107] 4) The mixture of oil-water vapor and residue obtained in step 3) is separated into residue and oil-water vapor by a cyclone separator, and the oil-water vapor is separated into oil and water by condensation and standing, wherein the separated water enters the sewage treatment system and the oil is directly recycled.

[0108] According to the test, when the oil sludge is treated by the method of this embodiment, the amount of superheated steam used to treat one ton of oil sludge is 625 kg, the oil content of the residue is 3‰, and the water content is 8%.

[0109] Example 4

[0110] like Figure 1 As shown, this embodiment provides a method for treating oil sludge, wherein the oil sludge is oil sludge from a refinery oil separator, with a water content of 99% and an oil content of 1%.

[0111] The steps include:

[0112] 1) filtering and sieving the oil sludge through a 1 mm grid, filtering out large mechanical impurities of ≥1 mm, thereby obtaining oil sludge with a particle size of <1 mm, adding 0.1% of the weight of the oil sludge as a demulsifier, sorbitan laurate, to the filtered oil sludge, heating to 70° C. with stirring, allowing it to react fully and then standing for 30 minutes, then adding 0.08% of the weight of the oil sludge as a flocculant, polyferric sulfate, and 3.5% of the weight of the oil sludge as carbon black, continuing to stir, allowing it to react fully and then standing for another hour, to obtain pretreated oil sludge;

[0113] 2) conveying the pretreated sludge obtained in step 1) to a screw press for dehydration to obtain an oil-water mixture and dehydrated sludge, wherein the water content of the dehydrated sludge is 80%;

[0114] 3) passing saturated steam through a superheated steam generator (superheated steam generating device 9) to obtain superheated steam with a temperature of 500° C.; conveying the dehydrated sludge to a thermal sensing chamber, the superheated steam is accelerated to Mach 2.5 through a nozzle in the thermal sensing chamber, and the superheated steam is sprayed toward the dehydrated sludge. The superheated steam collides head-on with the sludge, and the oil and water in the sludge are evaporated under high temperature and high speed conditions to obtain a mixture of oil-water vapor and residue.

[0115] 4) The mixture of oil-water vapor and residue obtained in step 3) is separated into residue and oil-water vapor by a cyclone separator, and the oil-water vapor is separated into oil and water by condensation and standing, wherein the separated water enters the sewage treatment system and the oil is directly recycled.

[0116] According to the test, when the method of this embodiment is used to treat the oil sludge, the amount of superheated steam used to treat one ton of oil sludge is 1230 kg, the oil content of the residue is 1.5‰, and the water content is 10%.

[0117] Example 5

[0118] like Figure 2 As shown, this embodiment provides a method for treating oil sludge, wherein the oil sludge is oily sludge after wastewater treatment in a refinery, with a water content of 95%, an oil content of 3%, and a solid content of 2%.

[0119] The steps include:

[0120] 1) filtering and sieving the oil sludge through a 1 mm grid, filtering out large mechanical impurities of ≥1 mm, thereby obtaining oil sludge with a particle size of <1 mm, adding 0.05% of the weight of the oil sludge as a demulsifier, dodecyl sulfonic acid, to the filtered oil sludge, heating to 50° C. and stirring, allowing it to fully react and then standing for 60 minutes, then adding 0.01% of the weight of the oil sludge as a flocculant PAM and 5% of the weight of the oil sludge as coke powder, continuing to stir, allowing it to fully react and then standing for another 2 hours, to obtain pretreated oil sludge;

[0121] 2) conveying the pretreated sludge obtained in step 1) to a screw press for dehydration to obtain an oil-water mixture and dehydrated sludge, wherein the water content of the dehydrated sludge is 80%; conveying the dehydrated sludge to a low-temperature drying chamber, performing low-temperature drying and dehydration treatment on the sludge using hot air at 70° C. to dry the sludge, thereby obtaining secondary dehydrated sludge, wherein the water content of the secondary dehydrated sludge is 32%;

[0122] 3) passing saturated steam through a superheated steam generator (superheated steam generating device 9) to obtain superheated steam with a temperature of 550°C; conveying the secondary dehydrated sludge to a thermal sensing chamber, the superheated steam is accelerated to Mach 2 through a nozzle in the thermal sensing chamber, and superheated steam is sprayed toward the secondary dehydrated sludge, and the superheated steam collides head-on with the sludge, and the oil and water in the sludge are evaporated under high temperature and high speed conditions to obtain a mixture of oil-water vapor and residue.

[0123] 4) The mixture of oil-water vapor and residue obtained in step 3) is separated into residue and oil-water vapor by a cyclone separator, and the oil-water vapor is separated into oil and water by condensation and standing, wherein the separated water enters the sewage treatment system and the oil is directly recycled.

[0124] According to the test, when the method of this embodiment is used to treat the oil sludge, the amount of superheated steam used to treat one ton of oil sludge is 214 kg, the oil content of the residue is 2‰, and the water content is 7%.

[0125] Example 6

[0126] This embodiment provides a method for treating oil sludge, wherein the oil sludge is the bottom sludge of a refinery tank, with a water content of 90%, an oil content of 8%, and a solid content of 2%.

[0127] The steps include:

[0128] 1) Adding 0.01% of the weight of the sludge to the demulsifier triethanolamine oleate, heating to 40°C and stirring, allowing it to fully react and then standing for 10 minutes, then adding 0.1% of the weight of the sludge to the flocculant polyaluminium chloride and 3% of the weight of the sludge to the sawdust, continuing to stir, allowing it to fully react and then standing for another 3 hours to obtain the pretreated sludge;

[0129] 2) conveying the pretreated sludge obtained in step 1) to a screw press for dehydration to obtain an oil-water mixture and dehydrated sludge, wherein the water content of the dehydrated sludge is 60%; conveying the dehydrated sludge to a low-temperature drying chamber, performing low-temperature drying and dehydration treatment on the sludge using hot air at 50° C. to dry the sludge, to obtain secondary dehydrated sludge, wherein the water content of the secondary dehydrated sludge is 30%;

[0130] 3) passing saturated steam through a superheated steam generator (superheated steam generating device 9) to obtain superheated steam with a temperature of 700° C.; conveying the secondary dehydrated sludge to a thermal sensing chamber, the superheated steam is accelerated to Mach 1.5 through a nozzle in the thermal sensing chamber, and superheated steam is sprayed toward the secondary dehydrated sludge. The superheated steam collides head-on with the sludge, and the oil and water in the sludge are evaporated under high temperature and high speed conditions to obtain a mixture of oil-water vapor and residue.

[0131] 4) The mixture of oil-water vapor and residue obtained in step 3) is separated into residue and oil-water vapor by a cyclone separator, and the oil-water vapor is separated into oil and water by condensation and standing, wherein the separated water enters the sewage treatment system and the oil is directly recycled.

[0132] According to the test, when the method of this embodiment is used to treat the oil sludge, the amount of superheated steam used to treat one ton of oil sludge is 357 kg, the oil content of the residue is 2.6‰, and the water content is 8%.

[0133] Example 7

[0134] This embodiment provides a method for treating oil sludge, wherein the oil sludge is oil sludge from a grease trap of a refinery, with a water content of 19.79%, an oil content of 77.74%, and a solid content of 2.47%.

[0135] 1) adding straw powder in an amount of 1% by weight of the oil sludge to obtain oil sludge added with straw powder; passing saturated steam through a superheated steam generator (superheated steam generating device 9) to obtain superheated steam at a temperature of 400° C.; conveying the oil sludge added with straw powder to a thermal sensing chamber, accelerating the superheated steam to Mach 2.5 through a nozzle in the thermal sensing chamber, spraying the superheated steam to the oil sludge, causing the superheated steam to collide head-on with the oil sludge, evaporating oil and water in the oil sludge under high temperature and high speed conditions, and obtaining a mixture of oil-water vapor and residue.

[0136] 2) The mixture of oil, water vapor and residue obtained in step 1) is separated into residue and oil, water vapor by a cyclone separator, and the oil, water vapor is condensed and allowed to stand to separate into oil and water, wherein the separated water enters a sewage treatment system, and the oil is directly recycled.

[0137] According to the test, when the method of this embodiment is used to treat the oil sludge, the amount of superheated steam used to treat one ton of oil sludge is 1 ton, the oil content of the residue is 3‰, and the water content is 2%.

[0138] Example 8

[0139] This embodiment provides a method for treating oil sludge, wherein the oil sludge is oil sludge from a grease trap of a refinery, with a water content of 75.6%, an oil content of 13.8%, and a solid content of 10.52%.

[0140] 1) adding sawdust in an amount of 2% by weight of the oil sludge to the oil sludge to obtain oil sludge with sawdust added thereto; transporting the oil sludge with sawdust added thereto to a low-temperature drying chamber, and subjecting the oil sludge with sawdust added thereto to low-temperature drying and dehydration treatment by using hot air at 75° C. to dry the oil sludge to obtain dehydrated oil sludge, wherein the water content of the dehydrated oil sludge is 30%;

[0141] 2) passing saturated steam through a superheated steam generator (superheated steam generating device 9) to obtain superheated steam with a temperature of 500° C.; conveying the dehydrated sludge to a thermal sensing chamber, the superheated steam is accelerated to Mach 2.0 through a nozzle in the thermal sensing chamber, and superheated steam is sprayed toward the dehydrated sludge. The superheated steam collides head-on with the sludge, and the oil and water in the sludge are evaporated under high temperature and high speed conditions to obtain a mixture of oil-water vapor and residue.

[0142] 3) The mixture of oil-water vapor and residue obtained in step 2) is separated into residue and oil-water vapor through a cyclone separator, and the oil-water vapor is subjected to heat exchange through a heat exchanger. After the heat exchange, the oil-water vapor is preliminarily cooled, and heat is transferred to the cold air in the heat exchanger, so that the temperature of the cold air is increased to become hot air, and the hot air enters the low-temperature drying chamber to continue to perform low-temperature drying and dehydration treatment on the oil sludge; the preliminarily cooled oil-water vapor is condensed and allowed to stand to separate into oil and water, wherein the separated water enters the sewage treatment system, and the oil is directly recycled.

[0143] According to the test, when the oil sludge is treated by the method of this embodiment, the amount of superheated steam used to treat one ton of oil sludge is 348 kg, the oil content of the residue is 2.1‰, and the water content is 6%.

[0144] Comparative Example 1

[0145] This comparative example provides a method for treating oil sludge, wherein the oil sludge is oily sludge after wastewater treatment in a refinery, with a water content of 95%, an oil content of 3%, and a solid content of 2%.

[0146] The steps include:

[0147] 1) Add 0.05% of the weight of the sludge to the demulsifier dodecyl sulfonic acid, heat to 50°C and stir, allow it to react fully and then stand for 20 minutes, then add 0.02% of the weight of the sludge to the flocculant PAM, continue stirring, allow it to react fully and then stand for another 2 hours to obtain the pretreated sludge;

[0148] 2) conveying the pretreated sludge obtained in step 1) to a screw press for dehydration to obtain an oil-water mixture and dehydrated sludge, wherein the water content of the dehydrated sludge is 80%;

[0149] 3) passing saturated steam through a superheated steam generator (superheated steam generating device 9) to obtain superheated steam with a temperature of 550°C; conveying the dehydrated sludge to a thermal sensing chamber, the superheated steam is accelerated to Mach 2 through a nozzle in the thermal sensing chamber, and superheated steam is sprayed toward the dehydrated sludge. The superheated steam collides head-on with the sludge, and the oil and water in the sludge are evaporated under high temperature and high speed conditions to obtain a mixture of oil-water vapor and residue.

[0150] 4) The mixture of oil-water vapor and residue obtained in step 3) is separated into residue and oil-water vapor by a cyclone separator, and the oil-water vapor is separated into oil and water by condensation and standing, wherein the separated water enters the sewage treatment system and the oil is directly recycled.

[0151] According to the test, when the method of this embodiment is used to treat the oil sludge, the amount of superheated steam used to treat one ton of oil sludge is 800 kg, the oil content of the residue is 2%, and the water content is 12%.

[0152] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for treating oily sludge, characterized in that: The steps include: 1) Spraying superheated steam at a temperature of 400-700°C to the oil sludge added with carbonaceous additives to obtain a mixture of oil, water vapor and residue; 2) performing gas-solid separation on the mixture of oil, water vapor and residue obtained in step 1) to obtain oil, water vapor and residue, and performing liquid-liquid separation on the oil, water vapor to obtain oil and water; Before spraying superheated steam to the oil sludge added with the carbonaceous additive, the step of dehydrating the oil sludge added with the carbonaceous additive is also included; The step of dehydrating the oil sludge added with the carbonaceous additive comprises: a) adding a demulsifier, a flocculant and a carbon additive to the oil sludge in sequence to obtain pretreated oil sludge; b) dehydrating the pretreated sludge obtained in step a); The carbonaceous additive is selected from one or more of coke, sawdust, carbon black, wood chips, straw, and rice straw, and the amount of the carbonaceous additive is 1-5% of the weight of the oil sludge.

2. The oil sludge treatment method according to claim 1, characterized in that: Step b) further includes the step of low-temperature drying and dehydrating the dehydrated oil sludge; The low temperature drying temperature is 50-75°C.

3. The oil sludge treatment method according to claim 1, characterized in that: In step 2), before the oil-water vapor is subjected to liquid-liquid separation, a step of exchanging heat between the oil-water vapor and the oil-water vapor is also included.

4. The oil sludge treatment method according to claim 1, characterized in that: In step a), before adding the demulsifier to the oil sludge, the step of filtering and screening the oil sludge is also included; After filtering and screening the oil sludge, the particle size of the oil sludge is less than 1 mm.

5. The oil sludge treatment method according to claim 1, characterized in that: The demulsifier is used in an amount of 0.01-0.1% of the weight of the sludge; The dosage of the flocculant is 0.01-0.1% of the weight of the sludge.

6. An oil sludge treatment system, which is a system used in the oil sludge treatment method according to claims 1 to 5, characterized in that: The oil sludge treatment system comprises a screening device, a demulsifier, a flocculation device, a dehydration device, a thermal sensing device, a cyclone separation device, and a cooling oil-water separation device which are sequentially connected through an oil sludge conveying pipeline; wherein the demulsifier is also provided with a demulsifier feed port, the flocculation device is also provided with an additive feed port, the dehydration device is also provided with a wastewater discharge port, and the thermal sensing device is also provided with a superheated steam inlet; The additive inlet includes a flocculant inlet and a carbonaceous additive inlet; The carbonaceous additive is selected from one or more of coke, sawdust, carbon black, wood chips, straw, and rice straw; the amount of the carbonaceous additive is 1-5% of the weight of the oil sludge.

7. The oil sludge treatment system according to claim 6, characterized in that: A low-temperature drying device is arranged between the dehydration device and the thermal sensing device, and is respectively connected to the dehydration device and the thermal sensing device through an oil sludge conveying pipeline.

8. The oil sludge treatment system according to claim 7, characterized in that: A heat exchange device is provided between the cyclone separation device and the cooling oil-water separation device, and is connected to the cyclone separation device and the cooling oil-water separation device respectively through an oil-water conveying pipeline.

9. The oil sludge treatment system according to claim 8, characterized in that: The low-temperature drying device is also connected to the heat exchange device through a hot air delivery pipeline, and the heat exchange device is also provided with a cold air inlet.

Images