Treatment system and treatment method for high-water-content oil sludge of petrochemical enterprise

Abstract

The invention belongs to the field of comprehensive treatment of oil sludge, and relates to a high-water-content oil sludge treatment system and method for petrochemical enterprises. The system comprises a pretreatment unit, a three-phase separation unit and a modification drying unit, the pretreatment unit is connected with a high-water-content oil sludge feeding pipeline and a pretreatment unit discharging pipeline, and the pretreated material discharging pipeline is connected with the three-phase separation unit; the three-phase separation unit comprises a high-speed centrifugal machine, a low-speed centrifugal machine and an oil-water separator which are sequentially connected, a liquid-phase discharging pipeline of the low-speed centrifugal machine is connected with the oil-water separator, and a solid-phase discharging pipeline of the low-speed centrifugal machine is connected with the modification drying unit; the modification drying unit comprises a stirring machine and a drying machine which are connected in sequence, and the drying machine is connected with a dried oil sludge discharging pipeline. According to the method, the oil sludge subjected to three-phase separation is modified and dried, and compared with a conventional treatment technology that drying is carried out only after part of liquid phase is centrifuged, the method is higher in drying efficiency and higher in oil sludge decrement rate.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive oil sludge treatment, and in particular, relates to a high-water-content oil sludge treatment system and a high-water-content oil sludge treatment method for a petrochemical enterprise. Background Art

[0002] Oil sludge from petrochemical enterprises refers to the general term for hazardous solid wastes containing a large amount of petroleum components that are generated by petrochemical enterprises during the process of oil refining, chemical industry, and sewage treatment. Among them, high-water-content oil sludge is mainly produced during sewage treatment, and generally includes grease trap sludge and flotation device scum. The main components of high-water-content oil sludge are water, petroleum, primary minerals, secondary minerals, high-molecular organic matter, inorganic salts, and chemical agents added during sewage treatment. It has a complex composition, with an oil content of generally 3% to 10%, a water content of 80% to 95%, and a total liquid content of usually between 90% and 98%. It is an extremely stable emulsified system.

[0003] The traditional treatment process is to concentrate and dehydrate the high-water content oil sludge, reduce the liquid content from 98% to 99% to about 96%, add flocculants such as polyacrylamide to condition it, and then perform mechanical dehydration. In order to improve the centrifugal dehydration effect of oil sludge and facilitate maintenance and operation, some enterprises often mix the grease trap sludge and scum for dehydration. The liquid content of the oil sludge treated by this process is usually 80% to 85%, and the oil content is 5% to 15%, and it is outsourced to landfill as hazardous waste. However, the above treatment method has many disadvantages: (1) Dehydration can only complete solid-liquid separation, but cannot complete oil-water separation, making it difficult to recycle the petroleum in the oil sludge; (2) The water content of the oil sludge to be landfilled after treatment is high, the transportation and disposal cost is high, the stacking volume is large, and it also brings difficulties to deep treatment and disposal; (3) Landfill treatment occupies a large amount of land, posing a safety risk of polluting soil, groundwater and the surrounding environment. A large amount of volatile hydrocarbons and other organic pollutants will be emitted during the landfill process. Therefore, the research and development of new treatment technologies for high-water content oil sludge in petrochemical enterprises is of great significance.

[0004] At present, the new treatment technology of high-water sludge generally takes "reduction + drying" as the basic mode. The reduction still adopts demulsification and conditioning and mechanical dehydration processes, and there is still little application of oil, water and solid three-phase separation technology. Drying technology includes thermal drying, ultra-high temperature steam injection, new drying methods (including microwave drying, electro-osmosis drying and frying drying), etc., among which thermal drying technology is the most widely used. Thermal drying technology is divided into direct and indirect types. In the direct thermal drying process, the volatile petroleum substances will contact with the heat transfer medium to pollute the heat source, and there are certain safety risks. Therefore, it is not suitable for the treatment of oil sludge in petrochemical enterprises. The indirect thermal drying system has a simple process, simple operation, easy control of the device, and the water content of the sludge after drying can be adjusted and controlled. Therefore, it is more suitable for the treatment of oil sludge in petrochemical enterprises. However, the overall ductility of the sludge after the initial reduction treatment is large, and the fluidity and crushing are poor. Under normal circumstances, it is difficult to disperse into particles, and it is easy to adhere to the drying equipment, resulting in reduced drying efficiency.

[0005] In view of the problems that the existing petrochemical enterprises' high-water-content sludge reduction technology is difficult to recover petroleum and the drying technology is inefficient, the sludge three-phase separation technology and modified drying technology can be developed to improve the reduction efficiency of high-water-content sludge and effectively recover petroleum, thereby improving processing efficiency and reducing processing costs, which is of great significance. Summary of the invention

[0006] In view of the defects existing in the prior art, the purpose of the present invention is to provide a system and method for treating high-water-content oil sludge in petrochemical enterprises, so as to solve the problems that the existing high-water-content oil sludge treatment technology is difficult to recover petroleum and has low drying efficiency.

[0007] To achieve the above objectives, the first aspect of the present invention provides a high-water sludge treatment system for a petrochemical enterprise, the system comprising: a pretreatment unit, a three-phase separation unit and a modification and drying unit;

[0008] The pretreatment unit is connected with a high-water-content sludge feed pipeline and a pretreatment unit discharge pipeline, and the pretreatment material discharge pipeline is connected to the three-phase separation unit;

[0009] The three-phase separation unit comprises a high-speed centrifuge, a low-speed centrifuge and an oil-water separator connected in sequence, the low-speed centrifuge is provided with a low-speed centrifuge solid phase discharge pipeline and a low-speed centrifuge liquid phase discharge pipeline, the low-speed centrifuge liquid phase discharge pipeline is connected to the oil-water separator, and the low-speed centrifuge solid phase discharge pipeline is connected to the modified drying unit;

[0010] The modified drying unit comprises a stirrer and a drying machine which are connected in sequence, and the drying machine is connected to a drying sludge discharge pipeline.

[0011] The second aspect of the present invention provides a method for treating high-water-content oil sludge in a petrochemical enterprise, the method adopting the high-water-content oil sludge treatment system of the petrochemical enterprise, comprising the following steps:

[0012] Step 1, homogenization and demulsification: the high water content sludge of the petrochemical enterprise enters the pretreatment unit for homogenization and demulsification to obtain the pretreated material;

[0013] Step 2, three-phase separation: the pretreated material obtained in step 1 enters a three-phase separation unit, firstly undergoes high-speed centrifugation to obtain an oil phase and a water-solid mixture, the oil phase is recovered, and the water-solid mixture is further subjected to low-speed centrifugation to obtain a solid phase and a water phase, the water phase is then subjected to oil-water separation to recover a small amount of residual oil, and the solid phase is sent to a modified drying unit;

[0014] Step 3, modification and drying: the solid phase obtained in step 2 is put into a mixer and fully mixed with a modifier for modification. The obtained product is put into a dryer for heating and drying to obtain dried sludge.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. Compared with conventional treatment technology, the present invention adopts two-stage centrifugation to separate the oil, water and solid phases of high-water sludge, so that the oil phase can be recycled.

[0017] 2. Compared with conventional drying, the present invention uses a special modifier to modify the sludge before drying, so that its viscosity is reduced and its dispersibility is significantly enhanced, which is conducive to full drying and reduces the adhesion of sludge in the drying equipment.

[0018] 3. The oil sludge after three-phase separation is modified and dried. Compared with the conventional treatment technology of only centrifuging out part of the liquid phase for drying, the method of the present invention has higher drying efficiency and higher oil sludge reduction rate.

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0021] Figure 1 A flow chart of a method for treating high-water-content oil sludge in a petrochemical enterprise provided by an embodiment of the present invention is shown.

[0022] Figure 2 A schematic diagram of a high-water-content oil sludge treatment system for a petrochemical enterprise provided by an embodiment of the present invention is shown.

[0023] Figure 3 A schematic diagram of a high-water sludge treatment system for a petrochemical enterprise provided in a comparative example of the present invention is shown.

[0024] Description of reference numerals:

[0025] 1. Pretreatment unit; 2. Three-phase separation unit; 3. Modification and drying unit. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0027] To achieve the above objectives, the first aspect of the present invention provides a high-water sludge treatment system for a petrochemical enterprise, the system comprising: a pretreatment unit, a three-phase separation unit and a modification and drying unit;

[0028] The pretreatment unit is connected with a high-water-content sludge feed pipeline and a pretreatment unit discharge pipeline, and the pretreatment material discharge pipeline is connected to the three-phase separation unit;

[0029] The three-phase separation unit comprises a high-speed centrifuge, a low-speed centrifuge and an oil-water separator connected in sequence, the low-speed centrifuge is provided with a low-speed centrifuge solid phase discharge pipeline and a low-speed centrifuge liquid phase discharge pipeline, the low-speed centrifuge liquid phase discharge pipeline is connected to the oil-water separator, and the low-speed centrifuge solid phase discharge pipeline is connected to the modified drying unit;

[0030] The modified drying unit comprises a stirrer and a drying machine which are connected in sequence, and the drying machine is connected to a drying sludge discharge pipeline.

[0031] In the present invention, the pretreatment unit is used to homogenize and demulsify the sludge to destabilize its emulsified system; the three-phase separation unit is connected to the sludge outlet of the pretreatment unit, and is used to separate the oil, water and solid phases of the sludge to dehydrate, deoil and reduce the sludge, and separate and recover the oil phase; the modified drying unit is connected to the solid phase outlet of the three-phase separation unit, and is used to reduce the viscosity of the deliquated sludge, enhance the dispersibility, and further dry and reduce the sludge.

[0032] According to the present invention, preferably, the pretreatment unit includes a tempering tank, which includes but is not limited to a heating and heat preservation system, a temperature control system, a stirring system and a dosing system. The heating and heat preservation system heats up the tempering tank to ensure that the temperature in the tempering tank is suitable for demulsification conditions; the temperature control system appropriately adjusts the working conditions of the heating and heat preservation system according to the temperature measurement value in the tempering tank to ensure that the tempering tank operates stably under the set temperature conditions; the stirring system stirs the sludge to make it fully mixed with itself and the reagent; the dosing system quantitatively adds demulsifiers and other reagents to the tempering tank according to the set value.

[0033] Preferably, the high-speed centrifuge is a horizontal spiral centrifuge.

[0034] Preferably, the low-speed centrifuge is a horizontal spiral centrifuge.

[0035] Preferably, the oil-water separator is a gravity sedimentation type oil-water separator.

[0036] Preferably, the modification and drying unit comprises a mixer and a dryer connected in sequence.

[0037] Preferably, the mixer comprises one or more of a twin-shaft paddle mixer, a drum mixer or a ribbon mixer.

[0038] Preferably, the dryer includes one or more of a paddle dryer, a disc dryer, a belt dryer or a turbine thin layer dryer.

[0039] The high-water sludge treatment system for petrochemical enterprises provided by the present invention first homogenizes and demulsifies the oily sludge, and then separates the oil phase by high-speed centrifugation. The oil phase can be recycled. After separating the oil phase, the remaining water-solid mixture is further centrifuged at low speed for water-solid separation. The water phase enters the sewage treatment plant for treatment after further oil-water separation. The solid phase is modified and dried to reduce viscosity, enhance dispersibility, and further dry and reduce the amount. The high-water sludge treatment system realizes the three-phase separation of oil, water, and solid that cannot be achieved by traditional mechanical dehydration technology through two-stage centrifugation, so that petroleum can be recycled and the sludge is greatly reduced. At the same time, the viscosity of the solid phase obtained by centrifugation is reduced by modification, which further improves the drying efficiency. High-efficiency reduction treatment of high-water sludge is achieved.

[0040] The second aspect of the present invention provides a method for treating high-water-content oil sludge in a petrochemical enterprise, the method adopting the high-water-content oil sludge treatment system of the petrochemical enterprise, comprising the following steps:

[0041] Step 1, homogenization and demulsification: the high water content sludge of the petrochemical enterprise enters the pretreatment unit for homogenization and demulsification to obtain the pretreated material;

[0042] Step 2, three-phase separation: the pretreated material obtained in step 1 enters a three-phase separation unit, firstly undergoes high-speed centrifugation to obtain an oil phase and a water-solid mixture, the oil phase is recovered, and the water-solid mixture is further subjected to low-speed centrifugation to obtain a solid phase and a water phase, the water phase is then subjected to oil-water separation to recover a small amount of residual oil, and the solid phase is sent to a modified drying unit;

[0043] Step 3, modification and drying: the solid phase obtained in step 2 is put into a mixer and fully mixed with a modifier for modification. The obtained product is put into a dryer for heating and drying to obtain dried sludge.

[0044] In the present invention, the high-water content sludge is homogenized, and a demulsifier is added to increase the temperature for demulsification, which prevents the fluctuation of the sludge composition from affecting the subsequent steps, destabilizes the sludge emulsification system, and improves the demulsification efficiency by increasing the temperature.

[0045] According to the present invention, preferably, the demulsification conditions include: demulsifying the high water content oil sludge by increasing the temperature in the presence of a demulsifier.

[0046] Preferably, the dosage of the demulsifier is 1 to 7 g per liter of water-containing sludge.

[0047] Preferably, the conditions for heating demulsification include: a temperature of 50 to 70° C. and a residence time of 30 to 90 minutes.

[0048] According to the present invention, preferably, the modifier comprises a mixture of an organic ammonium salt and an acrylamide copolymer, sodium lignin sulfonate and a calcium compound; the organic ammonium salt is at least one of methacrylamide β-hydroxypropyl trimethyl ammonium chloride, p-vinylbenzyl trimethyl ammonium chloride, methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide (2-methylbutyl) trimethyl ammonium chloride, and the calcium compound is calcium silicate and / or calcium aluminate; the ionicity of the organic ammonium salt and acrylamide copolymer is 20-40%.

[0049] In the present invention, the copolymer of organic ammonium salt and acrylamide is prepared by conventional preparation methods such as aqueous solution polymerization, dispersion polymerization, reverse emulsion polymerization and the like.

[0050] Preferably, based on the total weight of the modifier, the content of the organic amine salt and acrylamide copolymer is 20-60wt%, the content of the calcium compound is 20-30wt%, and the content of the sodium lignin sulfonate is 10-60wt%.

[0051] According to a specific embodiment of the present invention, the modifier is a mixture of methacrylamide β-hydroxypropyltrimethylammonium chloride and acrylamide copolymer, p-vinylbenzyltrimethylammonium chloride and acrylamide copolymer, calcium silicate, calcium aluminate and sodium lignin sulfonate.

[0052] Preferably, based on the total weight of the modifier, the content of the copolymer of methacrylamide β-hydroxypropyltrimethylammonium chloride and acrylamide is 10-50wt%, the content of the copolymer of p-vinylbenzyltrimethylammonium chloride and acrylamide is 10-50wt%, the content of calcium silicate is 10-20wt%, the content of calcium aluminate is 10-20wt%, and the content of the sodium lignin sulfonate is 10-60wt%.

[0053] According to the present invention, preferably, the conditions for the mixed modification include: the dosage of the modifier is 10% to 30%, and the time is 3 to 10 minutes.

[0054] According to the present invention, preferably, the heating and drying temperature is 70-90°C.

[0055] According to the present invention, preferably, the conditions for high-speed centrifugation include: a drum speed of 2500-2900 rpm, a screw conveyor speed of 1200-1600 rpm, and a residence time of 2-4 min.

[0056] Preferably, the conditions for the low-speed centrifugation include: a drum speed of 1600-1900 rpm, a screw conveyor speed of 1500-1700 rpm, and a residence time of 2-4 min.

[0057] The main sources of the high-water content oil sludge in the present invention are the bottom sludge of the oil separator of petrochemical enterprises and the scum of the air flotation device.

[0058] Preferably, the high water content oil sludge has an oil content of 3% to 10% and a water content of 80% to 95%.

[0059] The present invention will be further described below in conjunction with embodiments, but the scope of the present invention is not limited to these embodiments.

[0060] The commercial information of the following substances in the examples of the present invention is as follows:

[0061] Methacrylamide β-hydroxypropyltrimethylammonium chloride was purchased from aladdin.

[0062] p-Vinylbenzyltrimethylammonium chloride was purchased from aladdin.

[0063] Methacrylamide β-hydroxypropyltrimethylammonium chloride was purchased from Sigma-Aldrich.

[0064] Sodium lignin sulfonate was purchased from TCI.

[0065] The ionicity of the copolymer of methacrylamide beta-hydroxypropyltrimethylammonium chloride and acrylamide is 30%.

[0066] The ionicity of the copolymer of p-vinylbenzyltrimethylammonium chloride and acrylamide is 30%.

[0067] The ionicity of the copolymer of methacrylamide beta hydroxypropyltrimethylammonium chloride and acrylamide is 30%.

[0068] Example 1

[0069] This embodiment provides a high water content oil sludge treatment system for a petrochemical enterprise, such as Figure 2As shown, the system includes: a pretreatment unit 1, a three-phase separation unit 2 and a modification and drying unit 3.

[0070] The pretreatment unit 1 is a conditioning tank, which is used to homogenize and demulsify the sludge to destabilize its emulsified system. The conditioning tank includes a heating and heat preservation system, a temperature control system, a stirring system and a dosing system. The pretreatment unit 1 is connected to a high-water sludge feed pipeline and a pretreatment unit discharge pipeline, and the pretreatment material discharge pipeline is connected to the three-phase separation unit 2.

[0071] The three-phase separation unit 2 is used to separate the oil, water and solid phases of the sludge, dehydrate the sludge, remove oil and reduce its volume, and separate and recycle the oil phase. The three-phase separation unit 2 includes a high-speed centrifuge, a low-speed centrifuge and an oil-water separator connected in sequence, the high-speed centrifuge is a horizontal spiral centrifuge, the oil-water separator is a gravity sedimentation oil-water separator, the low-speed centrifuge is a horizontal spiral centrifuge, and the low-speed centrifuge is provided with a low-speed centrifuge solid phase discharge pipeline and a low-speed centrifuge liquid phase discharge pipeline, the low-speed centrifuge liquid phase discharge pipeline is connected to the oil-water separator, and the low-speed centrifuge solid phase discharge pipeline is connected to the modified drying unit 3.

[0072] The modified drying unit 3 is used to reduce the viscosity of the deliquidated sludge, enhance the dispersibility, and further dry and reduce the amount. The modified drying unit 3 includes a mixer and a dryer connected in sequence. The mixer is a double-shaft paddle mixer, and the dryer is a paddle dryer. The dryer is connected to a dried sludge discharge pipeline.

[0073] Example 2

[0074] This embodiment provides a high-water-content oil sludge treatment system for a petrochemical enterprise. Compared with Embodiment 1, except that the mixer in the modified drying unit 3 is a drum mixer and the dryer is a disc dryer, the rest is the same as Embodiment 1.

[0075] Example 3

[0076] This embodiment provides a method for treating high water content oil sludge in a petrochemical enterprise, using the method shown in FIG. Figure 2 The system shown in the figure is carried out, and its process flow is as follows Figure 1 As shown, the composition of the high-water content oil sludge to be treated is: 5% oil content, 90% water content, and the rest is solid phase. The process includes the following steps:

[0077] Step 1, homogenization and demulsification: homogenize the high water content sludge of the petrochemical enterprise, and add demulsifier to increase the temperature and demulsify, the temperature is 60℃, and the residence time is 60min;

[0078] Step 2, the homogeneous demulsified sludge obtained in step 1 is first subjected to high-speed centrifugal separation, the centrifugal drum speed is 2700rpm, the screw conveyor speed is 1400rpm, and the residence time is 3min, to obtain an oil phase and a water-solid mixture, the oil content of the oil phase is 98%, which can be recovered, and the water-solid mixture is further subjected to low-speed centrifugal separation, the centrifugal drum speed is 1700rpm, the screw conveyor speed is 1600rpm, and the residence time is 3min to obtain a solid phase and a water phase, the water content of the solid phase is 75%, and the oil content is 6%, and enters the modification and drying unit 3, the oil content of the water phase is reduced to 0.3%, and then the oil-water separation is recovered after a small amount of residual oil is sent to the petrochemical enterprise sewage treatment plant for further treatment;

[0079] Step 3, adding a modifier to the solid phase obtained in step 2 at a ratio of 20%, wherein the modifier is a mixture of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer, p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer, sodium lignin sulfonate, calcium silicate, and calcium aluminate, wherein the mass percentage of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer accounts for 20%, the mass percentage of p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer accounts for 25%, the mass percentage of calcium silicate accounts for 12%, the mass percentage of calcium aluminate accounts for 14%, and the mass percentage of sodium lignin sulfonate accounts for 29%, and the modification is fully mixed for 5 minutes, and the obtained product is heated and dried at 80° C. to obtain dried sludge, and the water content is reduced to 10%.

[0080] Example 4

[0081] This embodiment provides a method for treating high water content oil sludge in a petrochemical enterprise, using the method shown in FIG. Figure 2 The system shown in the figure is carried out, and its process flow is as follows Figure 1 As shown, the composition of the high-water content oil sludge to be treated is: 10% oil content, 80% water content, and the rest is solid phase. The process includes the following steps:

[0082] Step 1: homogenize the high water content sludge and add demulsifier to demulsify the sludge at a temperature of 70°C and a residence time of 30 minutes;

[0083] Step 2, the homogeneous demulsified sludge obtained in step 1 is first subjected to high-speed centrifugal separation, the centrifugal drum speed is 2900rpm, the screw conveyor speed is 1600rpm, and the residence time is 2min, to obtain an oil phase and a water-solid mixture, the oil content of the oil phase is 99%, which can be recovered, and the water-solid mixture is further subjected to low-speed centrifugal separation, the centrifugal drum speed is 1900rpm, the screw conveyor speed is 1700rpm, and the residence time is 2min to obtain a solid phase and a water phase, the water content of the solid phase is 72%, and the oil content is 7%, and enters the modified drying unit, the oil content of the water phase is reduced to 0.4%, and then the oil-water separation is recovered after a small amount of residual oil is sent to the petrochemical enterprise sewage treatment plant for further treatment;

[0084] Step 3, adding a modifier to the solid phase obtained in step 2 at a ratio of 30%, wherein the modifier is a mixture of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer, p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer, sodium lignin sulfonate, calcium silicate, and calcium aluminate, wherein the mass percentage of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer accounts for 10%, the mass percentage of p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer accounts for 30%, the mass percentage of calcium silicate accounts for 10%, the mass percentage of calcium aluminate accounts for 15%, and the mass percentage of sodium lignin sulfonate accounts for 35%, and the modification is fully mixed for 3 minutes, and the obtained product is heated and dried at 70° C. to obtain dried sludge, and the water content is reduced to 12%.

[0085] Example 5

[0086] This embodiment provides a method for treating high water content oil sludge in a petrochemical enterprise, using the method shown in FIG. Figure 2 The system shown in the figure is carried out, and its process flow is as follows Figure 1 As shown, the composition of the high-water content oil sludge to be treated is: 3% oil content, 95% water content, and the rest is solid phase. The process includes the following steps:

[0087] Step 1: homogenize the high water content sludge and add demulsifier to demulsify the sludge at a temperature of 50°C and a residence time of 90 minutes;

[0088] Step 2, the homogeneous demulsified sludge obtained in step 1 is first subjected to high-speed centrifugal separation, the centrifugal drum speed is 2500rpm, the screw conveyor speed is 1200rpm, and the residence time is 4min, to obtain an oil phase and a water-solid mixture, the oil content of the oil phase is 98%, which can be recovered, and the water-solid mixture is further subjected to low-speed centrifugal separation, the centrifugal drum speed is 1600rpm, the screw conveyor speed is 1500rpm, and the residence time is 4min to obtain a solid phase and a water phase, the water content of the solid phase is 79%, and the oil content is 2%, and enters the modified drying unit, the oil content of the water phase is reduced to 0.3%, and then the oil-water separation is recovered after a small amount of residual oil is sent to the petrochemical enterprise sewage treatment plant for further treatment;

[0089] Step 3, adding a modifier to the solid phase obtained in step 2 at a ratio of 10%, wherein the modifier is a mixture of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer, p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer, sodium lignin sulfonate, calcium silicate, and calcium aluminate, wherein the mass percentage of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer accounts for 30%, the mass percentage of p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer accounts for 10%, the mass percentage of calcium silicate accounts for 15%, the mass percentage of calcium aluminate accounts for 10%, and the mass percentage of sodium lignin sulfonate accounts for 35%, and the mixture is fully mixed and modified for 10 minutes, and the obtained product is heated and dried at 80° C. to obtain dried sludge, and the moisture content is reduced to 13%.

[0090] Example 6

[0091] This embodiment provides a method for treating high water content oil sludge in a petrochemical enterprise, using the method shown in FIG. Figure 2 The system shown in the figure is carried out, and its process flow is as follows Figure 1 As shown, except for adjusting the contents of different components in the modifier, other process parameters remain consistent with those in Example 3.

[0092] The composition of the high-water content oil sludge to be treated is: 5% oil content, 90% water content, and the rest is solid phase. The process includes the following steps:

[0093] Step 1: homogenize the high water content sludge and add demulsifier to demulsify the sludge at a temperature of 60°C and a residence time of 60 minutes;

[0094] Step 2, the homogeneous demulsified sludge obtained in step 1 is first subjected to high-speed centrifugal separation, the centrifugal drum speed is 2700rpm, the screw conveyor speed is 1400rpm, and the residence time is 3min, to obtain an oil phase and a water-solid mixture, the oil content of the oil phase is 98%, which can be recovered, and the water-solid mixture is further subjected to low-speed centrifugal separation, the centrifugal drum speed is 1700rpm, the screw conveyor speed is 1600rpm, and the residence time is 3min to obtain a solid phase and a water phase, the water content of the solid phase is 75%, and the oil content is 6%, and enters the modified drying unit, the oil content of the water phase is reduced to 0.3%, and then the oil-water separation is recovered after a small amount of residual oil is sent to the petrochemical enterprise sewage treatment plant for further treatment;

[0095] Step 3, adding a modifier to the solid phase obtained in step 2 at a ratio of 20%, wherein the modifier is a mixture of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer, p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer, sodium lignin sulfonate, calcium silicate, and calcium aluminate, wherein the mass percentage of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer accounts for 5%, the mass percentage of p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer accounts for 5%, the mass percentage of calcium silicate accounts for 5%, the mass percentage of calcium aluminate accounts for 5%, and the mass percentage of sodium lignin sulfonate accounts for 80%. The solid phase is fully mixed and modified for 5 minutes, and the obtained product is heated and dried at 80°C. After heating, only a wet and sticky product is obtained, the dispersibility is poor, and the moisture content of the product is 34%.

[0096] Example 7

[0097] This embodiment provides a method for treating high water content oil sludge in a petrochemical enterprise, using the method shown in FIG. Figure 2 The system shown in the figure is carried out, and its process flow is as follows Figure 1 As shown, except for adjusting the contents of different components in the modifier, other process parameters remain consistent with those in Example 3.

[0098] The composition of the high-water content oil sludge to be treated is: 5% oil content, 90% water content, and the rest is solid phase. The process includes the following steps:

[0099] Step 1: homogenize the high water content sludge and add demulsifier to demulsify the sludge at a temperature of 60°C and a residence time of 60 minutes;

[0100] Step 2, the homogeneous demulsified sludge obtained in step 1 is first subjected to high-speed centrifugal separation, the centrifugal drum speed is 2700rpm, the screw conveyor speed is 1400rpm, and the residence time is 3min, to obtain an oil phase and a water-solid mixture, the oil content of the oil phase is 98%, which can be recovered, and the water-solid mixture is further subjected to low-speed centrifugal separation, the centrifugal drum speed is 1700rpm, the screw conveyor speed is 1600rpm, and the residence time is 3min to obtain a solid phase and a water phase, the water content of the solid phase is 75%, and the oil content is 6%, and enters the modified drying unit, the oil content of the water phase is reduced to 0.3%, and then the oil-water separation is recovered after a small amount of residual oil is sent to the petrochemical enterprise sewage treatment plant for further treatment;

[0101] Step 3, adding a modifier to the solid phase obtained in step 2 at a ratio of 20%, wherein the modifier is a mixture of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer, p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer, sodium lignin sulfonate, calcium silicate, and calcium aluminate, wherein the mass percentage of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer accounts for 40%, the mass percentage of p-vinylbenzyltrimethyl ammonium chloride and acrylamide copolymer accounts for 40%, the mass percentage of calcium silicate accounts for 5%, the mass percentage of calcium aluminate accounts for 5%, and the mass percentage of sodium lignin sulfonate accounts for 10%, and the modification is fully mixed for 5 minutes. The obtained product is heated and dried at 80°C. After heating, the surface of the product oozes oil, the dispersibility is poor, and the water content of the product is 28%.

[0102] Example 8

[0103] This embodiment provides a method for treating high water content oil sludge in a petrochemical enterprise, using the method shown in FIG. Figure 2 The system shown in the figure is carried out, and its process flow is as follows Figure 1 As shown, except for adjusting the different components in the modifier, other process parameters remain consistent with Example 3.

[0104] The composition of the high-water content oil sludge to be treated is: 5% oil content, 90% water content, and the rest is solid phase. The process includes the following steps:

[0105] Step 1: homogenize the high water content sludge and add demulsifier to demulsify the sludge at a temperature of 60°C and a residence time of 60 minutes;

[0106] Step 2, the homogeneous demulsified sludge obtained in step 1 is first subjected to high-speed centrifugal separation, the centrifugal drum speed is 2700rpm, the screw conveyor speed is 1400rpm, and the residence time is 3min, to obtain an oil phase and a water-solid mixture, the oil content of the oil phase is 98%, which can be recovered, and the water-solid mixture is further subjected to low-speed centrifugal separation, the centrifugal drum speed is 1700rpm, the screw conveyor speed is 1600rpm, and the residence time is 3min to obtain a solid phase and a water phase, the water content of the solid phase is 75%, and the oil content is 6%, and enters the modified drying unit, the oil content of the water phase is reduced to 0.3%, and then the oil-water separation is recovered after a small amount of residual oil is sent to the petrochemical enterprise sewage treatment plant for further treatment;

[0107] Step 3, adding a modifier to the solid phase obtained in step 2 at a ratio of 20%, wherein the modifier is a mixture of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer, acrylamide (2-methylbutyl) trimethyl ammonium chloride and acrylamide copolymer, sodium lignin sulfonate, calcium silicate, and calcium aluminate, wherein the mass percentage of methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide copolymer accounts for 20%, the mass percentage of acrylamide (2-methylbutyl) trimethyl ammonium chloride and acrylamide copolymer accounts for 25%, the mass percentage of calcium silicate accounts for 12%, the mass percentage of calcium aluminate accounts for 14%, and the mass percentage of sodium lignin sulfonate accounts for 29%, and the modified phase is fully mixed for 5 minutes, and the obtained product is heated and dried at 80° C. to obtain dried sludge, and the water content is reduced to 19%.

[0108] Example 9

[0109] The only difference from Example 3 is that in step 3, the modifier is added at a ratio of 5%. The dried oil sludge is obtained with a water content of 17%.

[0110] Comparative Example 1

[0111] This comparative example provides a high-water-content oil sludge treatment system for a petrochemical enterprise, wherein the high-water-content oil sludge treatment system for a petrochemical enterprise is as follows: Figure 3 As shown, compared with Example 1, except that the three-phase separation unit is replaced by a conventional single centrifuge in the art, and the modified drying unit is replaced by a conventional paddle dryer in the art, the rest is the same as Example 1.

[0112] The centrifuge is connected to the oil sludge outlet of the pretreatment unit 1 and is used for liquid-solid separation of the oil sludge, so as to dehydrate, deoil and reduce the oil sludge.

[0113] The paddle dryer is connected to the solid phase outlet of the centrifuge and is used to dry and reduce the oil sludge after deliquoring.

[0114] Since a single centrifuge can only separate solids and liquids, oil and water are mixed in the liquid phase. Compared with the three-phase separation unit, the oil phase cannot be separated separately, resulting in its inability to be recycled. In addition, since it only undergoes one-stage centrifugation, the output solid phase has a high liquid content, which increases the energy consumption of the drying process. Compared with the modified drying unit, since the solid phase enters the paddle dryer directly without modification, the solid phase has high viscosity and is easy to adhere to the inner wall and paddles of the dryer, which seriously affects the drying efficiency.

[0115] The method for treating high-water-content sludge in a petrochemical enterprise in this comparative example is consistent with that in Application Example 3 except that the three-phase separation unit is replaced by a conventional single centrifuge and the modified drying unit is replaced by a conventional paddle dryer.

[0116] The composition of the high-water content oil sludge to be treated is: 5% oil content and 90% water content. The process includes the following steps:

[0117] Step 1: homogenize the high water content sludge and add demulsifier to demulsify the sludge at a temperature of 60°C and a residence time of 60 minutes;

[0118] Step 2: Centrifuge the homogenized demulsified sludge obtained in step 1 for a residence time of 6 minutes to obtain a solid phase and a liquid phase (oil-water mixture). The solid phase has a water content of 85% and an oil content of 4%. The solid phase enters a paddle dryer, and the liquid phase is directly sent to a petrochemical enterprise sewage treatment plant for further treatment. The oil phase cannot be recovered.

[0119] Step 3: The solid phase obtained in step 2 is heated and dried at 80° C. using a paddle dryer to obtain dried oil sludge, the moisture content of which is reduced to only 26%.

[0120] In summary, the high-water-content sludge treatment system and method for petrochemical enterprises provided by the present invention first homogenizes and demulsifies the high-water-content sludge, and then performs high-speed centrifugation to separate the oil phase and the water-solid mixture, the oil phase can be recycled, and the water-solid mixture is subjected to low-speed centrifugation to obtain the solid phase and the water phase, and the solid phase is modified and dried to obtain the dried sludge. The high-water-content sludge treatment system for petrochemical enterprises achieves the separation of oil, water, and solid phases of high-water-content sludge through two-stage centrifugation, solves the problem that the oil phase is difficult to recycle in traditional technologies, and solves the problems of low drying efficiency and low sludge reduction rate in traditional technologies through modification before drying, truly realizing efficient reduction treatment of high-water-content sludge.

[0121] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0122] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A high water content sludge treatment system for a petrochemical enterprise, characterized in that: The system comprises: a pretreatment unit, a three-phase separation unit and a modification and drying unit; The pretreatment unit is connected with a high-water-content sludge feed pipeline and a pretreatment unit discharge pipeline, and the pretreatment material discharge pipeline is connected to the three-phase separation unit; The three-phase separation unit comprises a high-speed centrifuge, a low-speed centrifuge and an oil-water separator connected in sequence, the low-speed centrifuge is provided with a low-speed centrifuge solid phase discharge pipeline and a low-speed centrifuge liquid phase discharge pipeline, the low-speed centrifuge liquid phase discharge pipeline is connected to the oil-water separator, and the low-speed centrifuge solid phase discharge pipeline is connected to the modified drying unit; The modified drying unit comprises a stirrer and a drying machine which are connected in sequence, and the drying machine is connected to a drying sludge discharge pipeline.

2. The high water content sludge treatment system for petrochemical enterprises according to claim 1, wherein: The pretreatment unit comprises a tempering tank, and the tempering tank comprises a heating and heat preservation system, a temperature control system, a stirring system and a dosing system.

3. The high water content sludge treatment system for petrochemical enterprises according to claim 1, wherein: The mixer is selected from at least one of a double-shaft paddle mixer, a drum mixer and a ribbon mixer, and the dryer is selected from at least one of a paddle dryer, a disc dryer, a belt dryer and a turbine thin-layer dryer.

4. The high water content sludge treatment system for petrochemical enterprises according to claim 1, wherein: The high-speed centrifuge and the low-speed centrifuge are both horizontal spiral centrifuges, and the oil-water separator is a gravity sedimentation oil-water separator.

5. A method for treating high-water sludge in a petrochemical enterprise, characterized in that: The method is carried out using the petrochemical enterprise high water content sludge treatment system as described in any one of claims 1 to 4, and comprises the following steps: Step 1, homogenization and demulsification: the high water content sludge of the petrochemical enterprise enters the pretreatment unit for homogenization and demulsification to obtain the pretreated material; Step 2, three-phase separation: the pretreated material obtained in step 1 enters a three-phase separation unit, firstly undergoes high-speed centrifugation to obtain an oil phase and a water-solid mixture, the oil phase is recovered, and the water-solid mixture is further subjected to low-speed centrifugation to obtain a solid phase and a water phase, the water phase is then subjected to oil-water separation to recover a small amount of residual oil, and the solid phase is sent to a modified drying unit; Step 3, modification and drying: the solid phase obtained in step 2 is put into a mixer and fully mixed with a modifier for modification. The obtained product is put into a dryer for heating and drying to obtain dried sludge.

6. The method for treating high-water-content oil sludge in a petrochemical enterprise according to claim 5, wherein: The demulsification conditions include: demulsifying the high water content oil sludge by heating in the presence of a demulsifier; The dosage of the demulsifier is 1 to 7 g for each increase in the water content of the sludge; The conditions for heating demulsification include: temperature of 50-70° C. and residence time of 30-90 min.

7. The method for treating high-water-content oil sludge in a petrochemical enterprise according to claim 5, wherein: The modifier comprises a mixture of an organic ammonium salt and acrylamide copolymer, sodium lignin sulfonate and a calcium compound; the organic ammonium salt is at least one of methacrylamide β-hydroxypropyl trimethyl ammonium chloride, p-vinylbenzyl trimethyl ammonium chloride, methacrylamide β-hydroxypropyl trimethyl ammonium chloride and acrylamide (2-methylbutyl) trimethyl ammonium chloride, and the calcium compound is calcium silicate and / or calcium aluminate; the ionicity of the organic ammonium salt and acrylamide copolymer is 20-40%; Preferably, based on the total weight of the modifier, the content of the organic amine salt and acrylamide copolymer is 20-60wt%, the content of the calcium compound is 20-30wt%, and the content of the sodium lignin sulfonate is 10-60wt%.

8. The method for treating high-water-content oil sludge in a petrochemical enterprise according to claim 7, wherein: The modifier is a mixture of methacrylamide beta-hydroxypropyltrimethylammonium chloride and acrylamide copolymer, p-vinylbenzyltrimethylammonium chloride and acrylamide copolymer, calcium silicate, calcium aluminate and sodium lignin sulfonate; Preferably, based on the total weight of the modifier, the content of the copolymer of methacrylamide β-hydroxypropyltrimethylammonium chloride and acrylamide is 10-50wt%, the content of the copolymer of p-vinylbenzyltrimethylammonium chloride and acrylamide is 10-50wt%, the content of calcium silicate is 10-20wt%, the content of calcium aluminate is 10-20wt%, and the content of the sodium lignin sulfonate is 10-60wt%.

9. The method for treating high-water-content oil sludge in a petrochemical enterprise according to claim 5, wherein: The mixed modification conditions include: the dosage of the modifier is 5% to 35%, preferably 10 to 30%, and the time is 3 to 10 minutes; The heating and drying temperature is 70-90°C.

10. The method for treating high-water-content oil sludge in a petrochemical enterprise according to claim 5, wherein: The conditions of the high-speed centrifugation include: a drum speed of 2500-2900 rpm, a screw conveyor speed of 1200-1600 rpm, and a residence time of 2-4 min.

11. The method for treating high water content oil sludge in petrochemical enterprises according to claim 5, wherein: The conditions of the low-speed centrifugation include: a drum speed of 1600-1900 rpm, a screw conveyor speed of 1500-1700 rpm, and a residence time of 2-4 min.

12. The method for treating high water content oil sludge in petrochemical enterprises according to claim 5, wherein: The high-water content oil sludge is the sludge from the oil separator of a petrochemical enterprise and / or the scum from the flotation device.

13. The method for treating high water content oil sludge in petrochemical enterprises according to claim 5, wherein: The high-water content oil sludge has an oil content of 3% to 10% and a water content of 80% to 95%.

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