A hot washing method and hot washing agent for oil-containing sludge

Abstract

The application discloses a kind of oily sludge hot washing method, its steps include that to be treated oily sludge is mixed with hot washing reagent uniformly, heated to 70~90 ℃, stirring 20~30 min, remove the mixture of upper layer floating oil and straw powder material, carry out solid-liquid separation and dry to the lower layer remaining sludge and carry out thermal desorption treatment.The above-mentioned hot washing reagent is made by mixing straw powder material, surfactant aqueous solution and cementing material.The application has the beneficial effect:one aspect improves the viscous and cohesive characteristics of oily sludge, improves the mass transfer, heat transfer efficiency in the process of hot washing;On the other hand, increase the dispersity of surfactant in straw powder material, increase the contact area of oily sludge and hot washing reagent in the process of hot washing, improve the efficiency of hot washing, reduce the amount of reagent, reduce the cost of repair.

Description

Technical Field

[0001] This invention relates to the field of oily sludge treatment technology, and in particular to a hot washing method and hot washing agent for oily sludge enhanced with crop straw. Background Technology

[0002] Oily sludge is one of the main solid wastes generated during crude oil extraction, transportation, storage, and refining. It is a multiphase system, typically composed of oil-in-water (O / W), water-in-oil (W / O), and suspended solids. These components are fully emulsified, have high viscosity, and are difficult to settle, making them challenging to treat. Due to limitations in treatment processes, sludge from different sources is currently often stockpiled together. As the amount of stockpiled sludge increases, it not only occupies land but also pollutes the surrounding soil, atmosphere, and water bodies due to its high hydrocarbon content, posing a threat to human health and the environment. With increasingly stringent pollution regulations in various regions, oily sludge has been included in China's "National Hazardous Waste List." To address this issue, technologies such as pyrolysis, solvent extraction, thermochemical cleaning, ultrasonic-assisted treatment, and combined treatment methods have emerged.

[0003] Among the aforementioned treatment methods, thermochemical cleaning utilizes solutions formulated with surfactants possessing both hydrophilic and lipophilic groups to clean oily sludge. The surfactants reduce interfacial tension and possess unique adsorption properties, and with the assistance of heating, mechanical stirring, and sedimentation, the oil, solid, and water phases are separated. Compared to other existing treatment methods, thermochemical cleaning is more widely used due to its advantages such as wide applicability, relatively mature technology, simple process, high degree of automation, and low equipment investment.

[0004] In the thermochemical cleaning of oily sludge, thermal cleaning agents play a crucial role. The cleaning solution used consists of a mixture of anionic and nonionic surfactants, additives, and water. However, due to the viscous and adhesive properties of oily sludge, the contact area between the sludge and the thermal cleaning agent is limited during the thermochemical cleaning process. This not only affects the efficiency of thermal cleaning but also leads to waste of the agent and increased remediation costs due to the relatively high dosage. Therefore, developing a widely available, inexpensive thermal cleaning agent that is easy to dispose of after use has significant economic and environmental benefits. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the existing technology by providing a method for hot washing of oily sludge using crop straw.

[0006] A second objective of this invention is to provide the aforementioned hot washing apparatus for oily sludge enhanced with crop straw.

[0007] A third objective of this invention is to provide a hot washing agent for hot washing of oily sludge.

[0008] To achieve the objectives of this invention, the technical solution adopted is as follows: a hot washing method for oily sludge, which utilizes crop straw for enhanced treatment, includes the following steps: mixing the oily sludge to be treated with a hot washing agent evenly, heating it with steam to 70-90°C, stirring for 20-30 minutes, removing the mixture of upper floating oil and straw powder, separating the lower layer of remaining sludge into solid and liquid components, drying the obtained solid sludge, and then performing thermal desorption treatment.

[0009] The hot washing method for oily sludge includes the following steps:

[0010] (1) Pretreatment of crop straw powder: Crush the dried crop straw in the farmland into straw powder of 70-90 mesh and keep it for later use;

[0011] (2) Preparation of hot washing agent: Mix straw powder, surfactant aqueous solution and gelling material, stir evenly to prepare hot washing agent with crop straw powder as surfactant adsorption carrier;

[0012] (3) Hot washing and purification of oily sludge: Add hot washing agent to the oily sludge to be treated, mix evenly, heat with steam to 70-90℃, stir for 20-30 minutes, filter the mixture of upper floating oil and straw powder, collect the floating oil, and send the straw powder to the hot desorption device for hot desorption treatment; the lower layer of remaining sludge is subjected to solid-liquid separation, the obtained solid sludge is dried and then sent to the hot desorption device for hot desorption treatment, and the supernatant, i.e. the purified cleaning liquid, is used again to clean the oily sludge.

[0013] The straw powder is made from crushed straw from crops such as wheat, corn, and cotton.

[0014] In step (3), the ratio of the amount of hot washing agent to the mass of oily sludge is (0.01:1) to (0.06:1).

[0015] A hot washing agent is prepared by mixing straw powder, an aqueous solution of surfactant, and a gelling material in the following weight ratios:

[0016] 50-100 parts of straw powder

[0017] 30-50 parts of surfactant aqueous solution

[0018] 5-10 parts of cementitious material.

[0019] The surfactant is one or a combination of two or more of cashew phenol polyoxyethylene ether, ethylene glycol, and silicate.

[0020] The gelling material is one or a combination of two or more of sodium lignosulfonate (C20H24Na2O10S2), calcium oxalate (Ca2C2O4), and triethanolamine.

[0021] The surfactant aqueous solution is prepared by dissolving the surfactant in water, wherein the mass fraction concentration of the surfactant is 20-30%.

[0022] The described hot washing method for oily sludge is based on an oily sludge hot washing device, which has advantages such as greatly improving efficiency and reducing operating costs. The oily sludge hot washing device includes a straw crusher, a belt conveyor, a kneader, a vibrating screen, a first screw conveyor, a second screw conveyor, a conditioning and washing device, a separation buffer tank, a solid-liquid separator, a third screw conveyor, an oil-water separator, a paddle dryer, a fourth screw conveyor, and an oil storage tank. The vibrating screen is installed above the inlet of the first screw conveyor, which is connected to the inlet of the conditioning and washing device via a pipeline. The straw crusher's outlet is connected to the belt conveyor's inlet via a pipeline, and the belt conveyor's outlet is connected to the kneader's inlet. The kneader is connected to the conditioning and washing device's inlet via the second screw conveyor. The uniformly mixed hot washing agent is conveyed to the conditioning and cleaning device. The conditioning and cleaning device is equipped with two discharge pipes. One discharge pipe is connected to the separation buffer tank, which is used to send the upper floating oil and straw powder mixture recovered after hot washing into the separation buffer tank for processing. The other discharge pipe is connected to the solid-liquid separator, which is used to send the lower residual sludge into the solid-liquid separator. The separation buffer tank is connected to the oil-water separator through a pipe. The oil-water separator is connected to the oil storage tank. The oil after the straw powder is filtered out in the separation buffer tank enters the oil-water separator through a pipe. After water removal, the oil enters the oil storage tank for temporary storage. The solid-liquid separator is connected to the paddle dryer through a third screw conveyor. The paddle dryer is connected to the thermal desorption device through a fourth screw conveyor.

[0023] Preferably, the straw crusher is installed above the feed inlet of the belt conveyor, and the discharge outlet of the straw crusher is connected to the feed inlet above the belt conveyor via a pipe. A gate is installed on the pipe to control the amount of straw powder entering the belt conveyor.

[0024] Preferably, the separation buffer tank is equipped with a filter screen for collecting straw powder and sending it to the thermal desorption device for processing.

[0025] Crop straw (processed through crushing and strict screening) has a porous structure. Mixing it with oily sludge can improve the sludge's viscosity and adhesion properties, increasing the contact area between the sludge and the washing agent during hot washing. Furthermore, the main components of crop straw are cellulose, hemicellulose, and lignin. The primary alcohol hydroxyl groups at C6 and secondary alcohol hydroxyl groups at C2 and C3 in the cellulose molecule, as well as the aromatic, methoxy, carbonyl, alcoholic, phenolic, and carboxyl groups in the lignin structure, can increase the number of adsorption functional groups through oxidation, esterification, and etherification reactions, making it an excellent source of natural adsorbents and a superior adsorption carrier for surfactants. This invention uses crop straw as a raw material, pre-treating it and then using it as an adsorption carrier for surfactants and an auxiliary agent in the hot washing process. It is mixed with surfactants and gelling materials to prepare a hot washing agent for the chemical cleaning of oily sludge, achieving excellent results.

[0026] Compared with existing technologies, this invention has the following advantages: It uses widely available and inexpensive crop straw powder as an adsorption carrier, mixed with surfactants and gelling materials to prepare a hot washing agent. On the one hand, the porous nature of the crop straw powder improves the viscosity and adhesion characteristics of oily sludge, increasing mass and heat transfer efficiency during the hot washing process. On the other hand, the cellulose contained in the crop straw powder has strong adsorption properties, allowing it to fully adsorb surfactants, increasing the dispersion of surfactants in the straw powder, increasing the contact area between the oily sludge and the hot washing agent during the hot washing process, improving hot washing efficiency, reducing agent dosage, and lowering remediation costs. Furthermore, using an oily sludge hot washing device as an auxiliary treatment can greatly improve efficiency and reduce operating costs. Attached Figure Description

[0027] Figure 1 The following is a system structural block diagram of the hot washing device for oily sludge according to the present invention, wherein the reference numerals are explained as follows: 1-Straw crusher, 11-Straw crusher inlet, 12-Straw crusher outlet, 13-Gate, 2-Belt conveyor, 21-Belt conveyor inlet, 3-Kneader, 31-Kneader inlet, 4-Vibrating screen, 5-First screw conveyor, 51-First screw conveyor inlet, 6-Second screw conveyor, 7-Conditioning and washing device, 8-Separation buffer tank, 81-Filter screen, 9-Solid-liquid separator, 10-Third screw conveyor, 14-Oil-water separator, 15-Oil storage tank, 16-Paddle dryer, 17-Fourth screw conveyor. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments. It should be noted that the embodiments do not constitute a limitation on the scope of protection of the present invention.

[0029] The oily sludge hot washing device, such as Figure 1As shown, the system includes a straw crusher 1, a vibrating screen 4, a belt conveyor 2, a first screw conveyor 5, a kneader 3, a second screw conveyor 6, a conditioning and cleaning device 7, a solid-liquid separator 9, a paddle dryer 16, a third screw conveyor 10, a fourth screw conveyor 17, a separation buffer tank 8, an oil-water separator 14, and an oil storage tank 15. The discharge end of the first screw conveyor 5 is connected to the inlet end of the conditioning and cleaning device 7 via a pipe; the vibrating screen 4 is connected to the first screw conveyor inlet 51 of the first screw conveyor 5. The vibrating screen 4 is installed above the first screw conveyor inlet 51, and the first screw conveyor 5 is provided with a first screw conveyor inlet 51 for receiving oily sludge from the screened material. The straw crusher 1's discharge port 12 is connected to the belt conveyor 2's feed port 21 via a pipe. The belt conveyor 2's discharge port is connected to the kneader 3's feed port 31. The kneader 3 is connected to the conditioning and cleaning device 7's feed end via a second screw conveyor 6, conveying the uniformly mixed hot washing agent to the conditioning and cleaning device 7. Preferably, the straw crusher 1 is installed above the belt conveyor feed port 21, and the straw crusher discharge port 12 is connected to the belt conveyor feed port 21 above the belt conveyor via a pipe. A gate 13 is installed on the pipe to control the amount of straw powder entering the belt conveyor 2. The kneader 3 has a kneader feed port 31 above it to receive the crushed straw powder, added surfactant aqueous solution, and gelling material from the belt conveyor 2's discharge end. The belt conveyor 2's discharge end is installed above the kneader feed port 31. The discharge end of the kneader 3 is connected to the conditioning and cleaning device 7 via a second screw conveyor 6, which transports the uniformly mixed hot washing agent to the conditioning and cleaning device 7 for processing. The conditioning and cleaning device 7 is equipped with two discharge pipes. One pipe is connected to the separation buffer tank 8, which is used to send the mixture of floating oil and straw powder recovered after hot washing into the separation buffer tank 8. The other pipe is connected to the solid-liquid separator 9, which is used to send the slurry remaining after oil recovery into the solid-liquid separator 9. The separation buffer tank 8 is equipped with a filter screen 81, which can collect the straw powder in the floating oil and send it to the thermal desorption device for processing. The separation buffer tank 8 is connected to the oil-water separator 14 via a pipe. The oil-water separator 14 is connected to the oil storage tank 15. After the straw powder is filtered out by the separation buffer tank 8, the remaining oil enters the oil-water separator 14 through a pipe. After water removal, the oil enters the oil storage tank 12 for temporary storage. After solid-liquid separation in the solid-liquid separator 9, the supernatant, which is the purified cleaning liquid, re-enters the conditioning and cleaning device 7 for cleaning oily sludge. The solid-liquid separator 9 is connected to the paddle dryer 16 via the third screw conveyor 10, and the paddle dryer 16 is connected to the thermal desorption device via the fourth screw conveyor 17.The remaining sludge after solid-liquid separation in the solid-liquid separator 9 enters the paddle dryer 16 through the third screw conveyor 10 for drying treatment; the discharge end of the paddle dryer 16 is connected to the fourth screw conveyor 17 through a pipeline, and the discharge from the paddle dryer 16 is transported to the thermal desorption device for processing through the fourth screw conveyor 17.

[0030] The solid-liquid separator 9 includes a sedimentation and flocculation hopper, a stirrer, a dosing tank, a centrifuge, and a screw propeller, used for further three-phase separation of the lower layer of residual sludge. The inlet of the sedimentation and flocculation hopper is connected to the slurry output pipe of the conditioning and washing device 7 and the output end of the solid-liquid separation dosing pump. The solid-liquid separation dosing pump is connected to the dosing tank. An stirrer is installed inside the sedimentation and flocculation hopper, and a screw propeller is installed at the bottom of the hopper. A centrifuge is installed at the outlet of the screw propeller, and the slag outlet of the centrifuge is connected to a paddle dryer 16 via a third screw conveyor 10. The separation buffer tank 8 is equipped with a filter screen 81 to separate straw powder from the floating oil, collect the straw powder, and send it to a thermal desorption device for further processing. The conditioning and hot washing device 7 includes a conditioning tank, a hot washing dosing tank, and an oil skimmer. The hot washing dosing tank is installed at the top of the conditioning tank and is used to add hot washing agents, which are then delivered to the conditioning tank via a metering pump. An oil skimmer is installed at the top of the conditioning tank to recover the upper layer of floating oil and straw powder mixture after hot washing and send it through a discharge pipe to a separation buffer tank 8 for further processing. The kneader 3 includes five main parts: a kneading section, a base section, a hydraulic system, a transmission system, and an electrical control system. It also contains a pair of rotating, mutually cooperating Σ-blades, which utilize the strong shearing action generated by the blades for mixing. The vibrating screen 4 has a perforated screen with a 3cm aperture. The oily sludge to be treated is screened by the vibrating screen 4. Sludge with a diameter less than 3cm falls into a temporary storage tank, while sludge and impurities with a diameter greater than 3cm are crushed and then transported back to the vibrating screen 4 for further screening. All the supporting unit components of the above-described structure of the present invention can be corresponding mature equipment available on the market. In specific implementation, the matching model can be flexibly selected and installed according to the design processing capacity of oily sludge according to the above-described structure.

[0031] Example 1

[0032] A method for hot washing oily sludge, based on the above-mentioned hot washing device for oily sludge, comprises the following steps:

[0033] Step 1: Add the naturally dried crop straw from the farmland into the straw crusher 1 through the feed inlet 11 of the straw crusher, and crush the crop straw into 80-mesh straw powder for later use;

[0034] Step 2: The straw powder is conveyed to the kneader 3 via the belt conveyor 2. At the same time, the gelling material and the surfactant aqueous solution are added through the feed port 31 of the kneader. The weight ratio of the straw powder, the surfactant aqueous solution and the gelling material is 90:50:10. The mass fraction concentration of the surfactant in the surfactant aqueous solution is 30%. After the three are mixed and stirred evenly, the hot washing agent is prepared.

[0035] Step 3: After being screened by vibrating screen 4 to remove impurities and large particles, 1 ton of oily sludge with an oil content of 25.3% and a water content of 49.8% enters the first screw conveyor 5 through the feed inlet 51 of the first screw conveyor. The first screw conveyor 5 transports the oily sludge to the conditioning and cleaning device 7. At the same time, the second screw conveyor 6 transports the hot washing agent with a mass ratio of 0.03:1 with the oily sludge to the conditioning and cleaning device 7 for thorough mixing. That is, for each treatment, 30 kg of hot washing agent is added for every 1 ton of oily sludge. After being mixed evenly, the mixture is heated to 80°C with steam and stirred for 30 minutes. The mixture of upper floating oil and straw powder is filtered through the separation buffer tank 8 to collect the floating oil. The straw powder is sent to the thermal desorption device for thermal desorption treatment. The floating oil is filtered through the oil-water separator 14 for oil-water separation and then temporarily stored in the oil storage tank 12. The lower layer of residual sludge in the conditioning and cleaning device 7 enters the solid-liquid separator 9 for solid-liquid separation. The supernatant, i.e., the separated liquid, is used again to clean the oily sludge. The sludge after solid-liquid separation is transported to the paddle dryer 16 through the third screw conveyor 10 for drying. After drying, it enters the thermal desorption device through the fourth screw conveyor 17 for thermal desorption treatment.

[0036] The oily sludge, with an oil content of 25.3% and a water content of 49.8%, comes from the bottom sludge of oil tanks produced during oilfield extraction. It is black in color and has a distinct odor. The straw powder is made from the naturally dried straw of typical crops such as wheat, corn, and cotton. It is brownish-yellow in color and has a water content of less than 3%.

[0037] After being cleaned and dried, the oily sludge underwent a significant color change, turning yellowish-brown. The odor disappeared, the material surface became dry, and the dispersibility improved. Tests showed that the oil content decreased to 1.8% and the moisture content to 7.5%.

[0038] Comparative Experiment 1-1

[0039] A method for hot washing oily sludge includes the following steps:

[0040] Step 1: Add the naturally dried crop straw from the farmland into the straw crusher 1 through the feed inlet 11 of the straw crusher. The crop straw is crushed into 80-mesh straw powder for later use.

[0041] Step 2: Add the gelling material and surfactant aqueous solution through the feed port 31 of the kneader. After mixing and stirring evenly, a hot washing agent is prepared. The weight ratio of surfactant aqueous solution to gelling material is 50:10, and the mass fraction concentration of surfactant in the surfactant aqueous solution is 30%. No straw powder is added to the hot washing agent prepared in this step.

[0042] Step 3: After being screened by vibrating screen 4 to remove impurities and large particles, 1 ton of oily sludge with an oil content of 25.3% and a water content of 49.8% enters the first screw conveyor 5 through the feed inlet 51 of the first screw conveyor. The first screw conveyor 5 transports the oily sludge to the conditioning and cleaning device 7. At the same time, the second screw conveyor 6 transports the hot washing agent with a mass ratio of 0.03:1 with the oily sludge to the conditioning and cleaning device 7 for thorough mixing. That is, for each treatment, 30 kg of hot washing agent is added for every 1 ton of oily sludge. After being mixed evenly, the mixture is heated to 80°C with steam and stirred for 30 minutes. The mixture of the upper floating oil and straw powder is filtered through the separation buffer tank 8 to collect the floating oil. The straw powder is sent to the thermal desorption device for thermal desorption treatment. The floating oil is filtered through the oil-water separator 14 and then temporarily stored in the oil storage tank 12. The lower layer of residual sludge in the conditioning and cleaning device 7 enters the solid-liquid separator 9 for solid-liquid separation. The supernatant from the solid-liquid separation is used again to clean the oily sludge. The sludge after solid-liquid separation is transported to the paddle dryer 16 through the third screw conveyor 10 for drying. After drying, it enters the thermal desorption device through the fourth screw conveyor 17 for thermal desorption treatment.

[0043] After being washed and dried, the oily sludge did not change color significantly, tending towards dark brown, and still had a noticeable odor. The material surface was relatively viscous and had poor dispersibility. The oil content was measured to be 17.1%, and the water content was 16.3%.

[0044] Comparative Experiment 1-2

[0045] A method for hot washing oily sludge includes the following steps:

[0046] Step 1: Add the naturally dried crop straw from the farmland into the straw crusher 1 through the feed inlet 11 of the straw crusher. The crop straw is crushed into 80-mesh straw powder for later use.

[0047] Step 2: The 80-mesh straw powder is conveyed to the kneader 3 through the belt conveyor 2. At the same time, the gelling material and surfactant aqueous solution are added through the feed port 31 of the kneader. The weight ratio of straw powder, surfactant aqueous solution and gelling material is 10:50:10. The mass fraction concentration of surfactant in the surfactant aqueous solution is 30%. After the three are mixed and stirred evenly, the hot washing agent is prepared.

[0048] Step 3: One ton of oily sludge with an oil content of 25.3% and a water content of 49.8% after being screened and impurities removed by vibrating screen 4 enters the first screw conveyor 5 through the feed inlet 51 of the first screw conveyor. The oily sludge is then transported to the conditioning and cleaning device 7 by the first screw conveyor 5. At the same time, a hot washing agent with a mass ratio of 0.03:1 to the oily sludge is transported to the conditioning and cleaning device 7 by the second screw conveyor 6 and thoroughly mixed. That is, for each treatment, 30 kg of hot washing agent is added for every ton of oily sludge. After being mixed evenly, the mixture is heated to 80°C with steam and stirred for 30 minutes. The mixture of the upper floating oil and straw powder is filtered through the separation buffer tank 8 to collect the floating oil. The straw powder is sent to the thermal desorption device for thermal desorption treatment. The floating oil is filtered through the oil-water separator 14 and then temporarily stored in the oil storage tank 12. The lower layer of residual sludge in the conditioning and cleaning device 7 enters the solid-liquid separator 9 for solid-liquid separation. The supernatant from the solid-liquid separation is used again to clean the oily sludge. The sludge after solid-liquid separation is transported to the paddle dryer 16 through the third screw conveyor 10 for drying. After drying, it enters the thermal desorption device through the fourth screw conveyor 17 for thermal desorption treatment.

[0049] After cleaning and drying, the oily sludge did not change color significantly, tending towards dark brown, and still had a noticeable odor. The material surface was relatively viscous and had poor dispersibility. The oil content was 14.7% and the water content was 13.6%.

[0050] Comparative Experiments 1-3

[0051] A method for hot washing oily sludge includes the following steps:

[0052] Step 1: Add the naturally dried crop straw from the farmland into the straw crusher 1 through the feed inlet 11 of the straw crusher. The crop straw is crushed into straw powder of 80 mesh and set aside for later use.

[0053] Step 2: The 80-mesh straw powder is conveyed to the kneader 3 through the belt conveyor 2. At the same time, the gelling material and surfactant aqueous solution are added through the feed port 31 of the kneader. The weight ratio of straw powder, surfactant aqueous solution and gelling material is 90:50:10. The mass fraction concentration of surfactant in the surfactant aqueous solution is 30%. After the three are mixed and stirred evenly, the hot washing agent is prepared.

[0054] Step 3: One ton of oily sludge with an oil content of 25.3% and a water content of 49.8% after being screened and impurities removed by vibrating screen 4 enters the first screw conveyor 5 through the feed inlet 51 of the first screw conveyor. The oily sludge is then transported to the conditioning and cleaning device 7 by the first screw conveyor 5. At the same time, a hot washing agent with a mass ratio of 0.005:1 to the oily sludge is transported to the conditioning and cleaning device 7 by the second screw conveyor 6 and thoroughly mixed. That is, for each treatment, 5 kg of hot washing agent is added for every ton of oily sludge. After being mixed evenly, the mixture is heated to 80°C with steam and stirred for 30 minutes. The mixture of the upper floating oil and straw powder is filtered through the separation buffer tank 8 to collect the floating oil. The straw powder is sent to the thermal desorption device for thermal desorption treatment. The floating oil is filtered through the oil-water separator 14 and then temporarily stored in the oil storage tank 12. The lower layer of residual sludge in the conditioning and cleaning device 7 enters the solid-liquid separator 9 for solid-liquid separation. The supernatant from the solid-liquid separation is used again to clean the oily sludge. The sludge after solid-liquid separation is transported to the paddle dryer 16 through the third screw conveyor 10 for drying. After drying, it enters the thermal desorption device through the fourth screw conveyor 17 for thermal desorption treatment.

[0055] After cleaning and drying, the oily sludge did not change color significantly, tending towards dark brown, and still had a noticeable odor. The material surface was relatively viscous and had poor dispersibility. The oil content was 19.2% and the water content was 17.9%.

[0056] Comparative experiments 1-4

[0057] A method for hot washing oily sludge includes the following steps:

[0058] Step 1: Add the naturally dried crop straw from the farmland into the straw crusher 1 through the feed inlet 11 of the straw crusher. The crop straw is crushed into 20-mesh straw powder for later use.

[0059] Step 2: The 20-mesh straw powder is conveyed to the kneader 3 through the belt conveyor 2. At the same time, the gelling material and surfactant aqueous solution are added through the feed port 31 of the kneader. The weight ratio of straw powder, surfactant aqueous solution and gelling material is 90:50:10. The mass fraction concentration of surfactant in the surfactant aqueous solution is 30%. After the three are mixed and stirred evenly, the hot washing agent is prepared.

[0060] Step 3: One ton of oily sludge with an oil content of 25.3% and a water content of 49.8% after being screened and impurities removed by vibrating screen 4 enters the first screw conveyor 5 through the feed inlet 51 of the first screw conveyor. The oily sludge is then transported to the conditioning and cleaning device 7 by the first screw conveyor 5. At the same time, a hot washing agent with a mass ratio of 0.03:1 to the oily sludge is transported to the conditioning and cleaning device 7 by the second screw conveyor 6 and thoroughly mixed. That is, for each treatment, 30 kg of hot washing agent is added for every ton of oily sludge. After being mixed evenly, the mixture is heated to 80°C with steam and stirred for 20-30 minutes. The mixture of the upper floating oil and straw powder is filtered through the separation buffer tank 8 to collect the floating oil. The straw powder is sent to the thermal desorption device for thermal desorption treatment. The floating oil is filtered through the oil-water separator 14 and then temporarily stored in the oil storage tank 12. The lower layer of residual sludge in the conditioning and cleaning device 7 enters the solid-liquid separator 9 for solid-liquid separation. The supernatant from the solid-liquid separation is used again to clean the oily sludge. The sludge after solid-liquid separation is transported to the paddle dryer 16 through the third screw conveyor 10 for drying. After drying, it enters the thermal desorption device through the fourth screw conveyor 17 for thermal desorption treatment.

[0061] After cleaning and drying, the oily sludge did not change color significantly, tending towards dark brown, and still had a noticeable odor. The material surface was relatively viscous and had poor dispersibility. The oil content was 12.8% and the water content was 11.7%.

[0062] Table 1 below is a comparative data list of the thermochemical cleaning method of oily sludge in Embodiment 1 of the present invention and the prior art, that is, the comparative example. The oily sludge is the bottom sludge generated during the oil extraction process in the oil field. Its oil content is 25.3%, water content is 49.8%, black color, and has a distinct odor.

[0063] Table 1

[0064]

[0065] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the description of the invention shall still fall within the scope of the patent of the present invention.

Claims

1. A hot wash medicament, characterized in that: It is made by mixing the following components in the following weight proportions: Straw powder 50-100 parts Surfactant aqueous solution 30-50 parts Gelled material 5-10 parts The straw powder is crushed to 70-90 mesh; the surfactant is one or more than two combinations of cardanol polyoxyethylene ether, ethylene glycol and silicate; the gelled material is one or more than two combinations of sodium lignosulfonate, calcium oxalate and triethanolamine; the surfactant aqueous solution is prepared by dissolving the surfactant in water, wherein the mass fraction concentration of the surfactant is 20-30%.

2. A hot wash method for oil-containing sludge, characterized by: The steps include: mixing the oil-containing sludge to be treated with the hot washing agent according to claim 1, heating to 70-90℃, stirring for 20-30 min, removing the mixture of the upper floating oil and the straw powder, and performing solid-liquid separation on the remaining sludge in the lower layer, drying the obtained solid sludge and then performing thermal desorption treatment.

3. A hot wash process for oil-containing sludge as claimed in claim 2, characterized in that: It includes the following steps: (1) Pretreatment of crop straw powder: crushing crop straw into 70-90 mesh straw powder; (2) Preparation of hot washing agent: mixing straw powder, surfactant aqueous solution and gelled material, and stirring uniformly to prepare the hot washing agent; (3) Hot washing purification of oil-containing sludge: adding the hot washing agent to the oil-containing sludge to be treated, mixing uniformly, heating to 70-90℃, stirring for 20-30 min, filtering the mixture of the upper floating oil and the straw powder to collect the floating oil, and sending the straw powder to a thermal desorption device for thermal desorption treatment; The remaining sludge in the lower layer is subjected to solid-liquid separation, and the obtained solid sludge is dried and then subjected to thermal desorption treatment in the thermal desorption device.

4. A hot wash process for oil-containing sludge as claimed in claim 3, characterized in that: The straw powder is wheat, corn or cotton straw powder crushed into powder.

5. A hot wash process for oil-containing sludge as claimed in claim 3, wherein: In step (3), the mass ratio of the hot washing agent to the oil-containing sludge is (0.01:1) to (0.06:1).

6. A hot wash process for oil-containing sludge as claimed in any one of claims 3 to 5, characterised in that: It is realized based on an oil-containing sludge hot washing device.

7. A hot wash process for oil-containing sludge as claimed in claim 6, characterized in that: The oil-containing sludge hot washing device comprises a straw crusher (1), a belt conveyor (2), a kneader (3), a vibrating screen (4), a first screw conveyor (5), a second screw conveyor (6), a conditioning and cleaning device (7), a separation buffer tank (8), a solid-liquid separator (9), a third screw conveyor (10), an oil-water separator (14), a paddle dryer (16), a fourth screw conveyor (17) and an oil storage tank (15). The vibrating screen (4) is installed above the first screw conveyor inlet (51) of the first screw conveyor, and the first screw conveyor (5) is connected to the inlet end of the conditioning and cleaning device (7) through a pipeline. The straw crusher outlet (12) of the straw crusher (1) is connected to the belt conveyor inlet (21) of the belt conveyor (2) through a pipeline, the outlet of the belt conveyor (2) is connected to the kneader inlet (31) of the kneader (3), and the kneader (3) is connected to the inlet end of the conditioning and cleaning device (7) through the second screw conveyor (6). The conditioning and cleaning device (7) is provided with two discharge pipelines, one of which is connected to the separation buffer tank (8), and the other of which is connected to the solid-liquid separator (9). The separation buffer tank (8) is connected with an oil-water separator (14) through a pipeline, and the oil-water separator (14) is connected with an oil storage tank (15); The solid-liquid separator (9) is connected with a paddle dryer (16) through a third screw conveyor (10), and the paddle dryer (16) is connected with a thermal desorption device through a fourth screw conveyor (17).

8. A hot wash process for oil-containing sludge as claimed in claim 7, characterized in that: The straw pulverizer (1) is installed above the feeding port (21) of the belt conveyor, the straw pulverizer discharge port (12) is connected with the feeding port (21) above the belt conveyor through a pipeline, and a gate (13) is arranged on the pipeline.

9. A hot wash process for oil-containing sludge as claimed in claim 8, characterized in that: A filter screen (81) is arranged in the separation buffer tank (8).

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