Method and device for deep dehydration of refinery three-sludge

Abstract

The present invention relates to the technical field of refining sludge dehydration, and is a method and device for deep dehydration of three types of sludge in refineries. The former is carried out according to the following steps: mixing the bottom sludge in the sludge sedimentation tank with the crude oil decalcification wastewater, and then stirring and conditioning; mechanically separating and dehydrating the conditioned sludge by means of pressure filtration dehydration or centrifugal dehydration to obtain the residual sludge; subjecting the residual sludge to electrochemical treatment to obtain the sludge after deep dehydration. The latter includes a reaction tank, electrodes and a vacuum pump. A third sludge pipeline is connected between the mechanical separation equipment and the reaction tank. The electrodes are installed in the reaction tank through a fixed cross beam, and a drain pipe is fixedly connected between the bottom outlet of the cavity and the inlet of the vacuum pump. The present invention has the characteristics of simple operation and low energy consumption. While improving the dehydration performance of the sludge, it deeply dehydrates the sludge. It can effectively reduce the usage amount of chemical conditioning agents in the sludge dehydration process, reduce the sludge treatment cost, and achieve the purpose of treating waste with waste.

Description

Technical Field

[0001] The invention relates to the technical field of refinery sludge dehydration, and is a method and device for deep dehydration of three kinds of sludge in a refinery. Background Art

[0002] A large amount of oily sludge is generated during the oil processing process, mainly from the oil sludge generated at the bottom of the oil tank during the production and processing of the refinery and the oil sludge generated during the subsequent sewage treatment process, referred to as "refinery three muds", which are divided into sludge in the oil separator, scum in the flotation tank, and residual activated sludge. Because the three refinery muds contain complex and diverse toxic and harmful compounds, and some of the compounds (benzene, polycyclic aromatic hydrocarbons, etc.) have the "three-cause" effects of teratogenicity, carcinogenicity, and mutagenicity, my country has added this type of high-risk waste to the national hazardous waste list. Moreover, oily sludge is a large type of hazardous waste. If it is discharged into the natural environment without reasonable treatment, it will not only cause a waste of resources, but also damage the ecological environment and cause pollution to the soil, water, air, etc. The reduction, resource utilization, and harmless treatment of oily sludge have become an inevitable trend for future development.

[0003] At present, domestic and foreign scholars have done a lot of research on sludge reduction technology, especially the development and research of sludge reduction process control and reduction technology, and have achieved certain results. It mainly focuses on the reduction of residual sludge in urban sewage treatment. For example, CN102718382A uses two-stage electrochemical direct oxidation technology to oxidize and decompose sludge with a water content of 99.6%. CN 105601073 A first adds an oxidant to the oily sludge before it enters the buffer tank, and adds calcium-containing reagents and aluminum-containing reagents before the sludge is mixed after sedimentation. After being treated in the mixer and filter tank, the oily sludge reduction treatment is completed. CN108409106A The present invention provides a microwave treatment method and equipment for oily sludge. There is little research on the reduction of the three muds in refineries.

[0004] Sludge reduction mainly refers to the process of sludge concentration and volume reduction. The purpose is to reduce the liquid content in the sludge and reduce the volume of the sludge for transportation and subsequent treatment and disposal. From the perspective of the sludge reduction process, it is divided into two stages: sludge source reduction and sludge process reduction. In the first stage, sludge source reduction, the main measure is to reduce the amount of sludge generated by screening agents and optimizing treatment conditions; in the second stage, sludge process reduction, mainly through sludge concentration and deliquification process to achieve sludge reduction.

[0005] At present, chemical conditioning agents represented by polyaluminium chloride (PAC), polyferric chloride (PFC) and polyacrylamide (PAM) are widely used in the process of sludge reduction. The role of chemical conditioning agents is to improve the sludge colloid structure, change the physical and chemical properties of sludge flocs such as surface potential, viscosity, moisture distribution, etc., promote sludge flocculation, and thus improve the sludge dewatering performance. After using the above conditioning agents, mechanical dehydration is used to achieve sludge reduction.

[0006] Common methods for reducing refinery sludge include pyrolysis treatment technology, incineration treatment technology, superheated steam injection treatment technology and sludge conditioning-mechanical dehydration technology.

[0007] Pyrolysis treatment technology refers to heating oily sludge to a higher temperature in the absence of oxygen or lack of oxygen. When a certain temperature is reached, the long-chain hydrocarbons in the sludge are broken and converted into light components, and the oil and gas are recovered by condensation. The residue after pyrolysis can be used for paving, preparing adsorption materials or directly landfilling. The pyrolysis method can well recycle the oil and gas resources in oily sludge. However, the pyrolysis device is expensive and has high requirements for equipment, and it has not been widely used in industry in China. Incineration treatment technology refers to sending the "three muds" that have been pre-dehydrated and concentrated to a certain degree of moisture content to an incinerator at a temperature of 800℃ to 850℃ for incineration. The ash formed can be used for paving, preparing adsorption materials or directly landfilling. After incineration, many harmful substances in the sludge are almost completely removed, reducing the harm to the environment and greatly reducing the volume and weight of the sludge. The disadvantages are high cost, complex equipment, high operating costs, and the smoke discharged during the incineration process contains pollutants such as dioxins. The main working principle of superheated steam jet treatment technology is that the superheated steam generated by the boiler is ejected at a certain speed through a special nozzle, colliding head-on with the sludge particles. Under the action of high temperature and the impulse generated by high speed, the oil and water adsorbed or contained in the sludge are evaporated. After the steam is cooled, the oil and water are separated. The crude oil can be directly recovered, and most of the oil in the waste residue can be removed. The water content in the treated sludge is generally around 30%, but the requirements for equipment are very high and the energy consumption is large.

[0008] Oil sludge conditioning-mechanical dehydration technology is a commonly used treatment technology for refining and chemical sludge in domestic refineries due to its low energy consumption, simple equipment, low operating costs, and mature technology. In the oil sludge conditioning system, the commonly used flocculants include high molecular inorganic flocculants such as polyaluminium chloride (PAC), polyferric chloride (PFC), polyacrylamide (PAM), and high molecular organic flocculants such as anionic, cationic, nonionic polyacrylamide and other long-chain macromolecules with high polymerization degree. At the same time, cationic organic flocculants or organic flocculants and lime are used before mechanical dehydration to improve the flocculation and dehydration effects. Chemical conditioning agents change the surface electrical properties and aggregation state of sludge solid particles through electrical neutralization and adsorption bridging, which can reduce the interstitial water content of sludge to a certain extent and promote the removal of free water in sludge. However, they have no obvious advantage in removing surface attached water and bound water. The water content of sludge after reduction by oily sludge conditioning-mechanical dehydration technology is about 80wt%. In order to achieve deep dehydration of sludge, quicklime (CaO) is widely used as a dehydration and solidification agent. Its essence is to use calcium ions (Ca 2+ ) can not only improve the sludge dewatering performance by compressing the double electric layer and adsorption-electric neutralization, but also improve the skeleton structure of sludge flocs, enhance the strength and compression resistance of sludge flocs, and reduce the collapse of flocs during filter press dewatering, thereby improving the sludge filter press dewatering performance. However, the dosage is usually 10wt% to 15wt% of the wet weight of the sludge, and the dosage is high and the volume expansion ratio is large. Furthermore, the large amount of chloride ions introduced into the sludge by the addition of polyaluminum chloride (PAC) and polyferric chloride (PFC) cannot be effectively separated from the sludge, which aggravates the risk of dioxin generation in the sludge incineration process and limits the application of sludge deep dehydration + thermal drying process. Summary of the invention

[0009] The present invention provides a method and device for deep dehydration of three kinds of mud in refineries, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problems of high calcium ion content in industrial wastewater and excessive sludge treatment cost in deep dehydration of three kinds of mud in refineries.

[0010] One of the technical solutions of the present invention is achieved by the following measures: a method for deep dehydration of three kinds of mud in a refinery, which is carried out according to the following steps: the first step is to mix the bottom mud in the sludge sedimentation tank with the crude oil decalcification wastewater, and then stir and condition it to obtain the conditioned sludge, wherein the volume ratio of the bottom mud in the sludge sedimentation tank to the crude oil decalcification wastewater is 0.5 to 1:1 to 2, the stirring and conditioning time is 30min to 120min, and the crude oil decalcification wastewater has a sodium ion content of 100mg / L to 2000mg / L and a calcium ion content of 1000mg / L to 30000mg / L; the second step is to collect the conditioned sludge Mechanical separation and dehydration are carried out by filter pressing or centrifugal dehydration to obtain residual sludge with a moisture content of less than 75%, wherein the filter pressing pressure during filter pressing dehydration is 0.1MPa to 1.5MPa, the filter pressing time is 0.5h to 4h, the centrifuge speed during centrifugal dehydration is 2500r / min to 4500r / min, and the centrifugation time is 5min to 30min; the third step is to electrochemically treat the residual sludge for 2h to 24h under the conditions of a temperature of 10°C to 90°C, an electrochemical action voltage of 5V to 36V, and an electrode spacing of 2cm to 50cm to obtain deeply dehydrated sludge.

[0011] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions:

[0012] The bottom sludge in the above-mentioned sludge sedimentation tank is the bottom sludge formed after the sludge generated by the oil separator, flotation tank, and A / O treatment unit enters the sludge sedimentation tank and settles.

[0013] In the first step above, in the crude oil decalcification wastewater, the sodium ion content is 500 mg / L to 2000 mg / L, and the calcium ion content is 3000 mg / L to 30000 mg / L.

[0014] The volume ratio of the bottom sludge in the above-mentioned sludge sedimentation tank to the crude oil decalcification wastewater is 0.5 to 1:1, and the stirring and conditioning time is 50 minutes to 90 minutes.

[0015] The filtration pressure of the above-mentioned filtration dehydration is 0.5MPa to 1.0MPa, and the filtration time is 1h to 2h; or / and, the centrifuge speed of the centrifuge dehydration is 3000r / min to 4000r / min, and the centrifugation time is 10min to 20min.

[0016] The conditions for electrochemical treatment of the above-mentioned residual sludge are: temperature of 30°C to 60°C, electrochemical action voltage of 10V to 36V, plate spacing of 5cm to 20cm, and electrochemical treatment time of 8h to 16h.

[0017] The second technical solution of the present invention is achieved through the following measures: a device for implementing a method for deep dehydration of three sludges in a refinery, comprising a sludge sedimentation tank, a sludge stirring tank, a mechanical separation device, an electrochemical device and a power supply, a first sludge pipeline is fixedly connected between the outlet of the sludge sedimentation tank and the upper inlet of the sludge stirring tank, a first sludge pump is fixedly installed on the first sludge pipeline, a crude oil decalcification wastewater pipeline is fixedly connected to the first sludge pipeline between the first sludge pump and the sludge stirring tank, a second sludge pipeline is fixedly connected between the bottom outlet of the sludge stirring tank and the inlet of the mechanical separation device, a second sludge pump is fixedly installed on the second sludge pipeline, a third sludge pipeline is fixedly connected between the mud outlet of the mechanical separation device and the mud inlet of the electrochemical device, a first sewage pipeline is fixedly connected to the water outlet of the mechanical separation device, a fourth sludge pipeline is fixedly connected to the mud outlet of the electrochemical device, a wastewater circulation pipeline is connected between the crude oil decalcification wastewater pipeline and the first sludge pipeline between the sludge stirring tank and the water outlet of the electrochemical device, and the electrochemical device is electrically connected to the power supply.

[0018] The following is a further optimization and / or improvement of the second technical solution of the above invention:

[0019] The electrochemical device includes a reaction tank, an electrode and a vacuum pump. A third sludge pipeline is fixedly connected between the mud outlet of the mechanical separation equipment and the mud inlet of the reaction tank. A fixed crossbeam capable of fixing the electrode is arranged on the electrode. The electrode is fixedly installed in the reaction tank through the fixed crossbeam. The electrode is electrically connected to a power supply. A cavity is arranged at the bottom of the reaction tank. A wastewater circulation pipeline is fixedly connected between the first sludge pipeline between the crude oil decalcification wastewater pipeline and the sludge stirring tank and the bottom outlet of the cavity. A vacuum pump is fixedly installed on the wastewater circulation pipeline.

[0020] The electrode is an iron electrode, which includes an anode and a cathode, and both the anode and the cathode are fixedly installed in the reaction tank through a fixed crossbeam.

[0021] A mesh screen with mesh numbers ranging from 50 to 200 is also provided at the bottom of the reaction tank.

[0022] The present invention has the characteristics of simple operation and low energy consumption. It can deeply dehydrate the sludge while improving the dewatering performance of the sludge. It can effectively reduce the use of chemical conditioners in the sludge dewatering process, reduce the sludge treatment cost, and achieve the purpose of treating waste with waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attached Figure 1 The figure is a schematic diagram of the process flow of the best embodiment of the present invention.

[0024] Attached Figure 2 It is a schematic diagram of the installation of the electrochemical device in the present invention.

[0025] The codes in the attached drawings are: 1 is a sludge sedimentation tank, 2 is a sludge stirring tank, 3 is a mechanical separation device, 4 is a vacuum pump, 5 is a first sludge pipeline, 6 is a first sludge pump, 7 is a crude oil decalcification wastewater pipeline, 8 is a second sludge pipeline, 9 is a second sludge pump, 10 is a third sludge pipeline, 11 is a first sewage pipeline, 12 is a fourth sludge pipeline, 13 is a wastewater circulation pipeline, 14 is an electrochemical device, 15 is a power supply, 16 is a reaction tank, 17 is a cavity, and 18 is an electrode. DETAILED DESCRIPTION

[0026] The present invention is not limited by the following embodiments, and specific implementation methods can be determined according to the technical scheme of the present invention and actual conditions. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all known and commonly used chemical reagents and chemicals in the prior art.

[0027] The present invention will be further described below in conjunction with embodiments:

[0028] Embodiment 1: As attached Figure 1 As shown, the method for deep dehydration of three kinds of mud in the refinery is carried out according to the following steps: the first step is to mix the bottom mud in the sludge sedimentation tank 1 with the crude oil decalcification wastewater, and then stir and condition it to obtain the conditioned sludge, wherein the volume ratio of the bottom mud in the sludge sedimentation tank 1 to the crude oil decalcification wastewater is 0.5 to 1:1 to 2, the stirring and conditioning time is 30 minutes to 120 minutes, and the crude oil decalcification wastewater has a sodium ion content of 100 mg / L to 2000 mg / L and a calcium ion content of 1000 mg / L to 30000 mg / L; the second step is to dehydrate the conditioned sludge by filter pressing or centrifugal dehydration. The method comprises the following steps: mechanically separating and dehydrating the sludge by water to obtain residual sludge with a moisture content of less than 75%, wherein the filtration pressure during filtration dehydration is 0.1 MPa to 1.5 MPa, the filtration time is 0.5 h to 4 h, the centrifuge speed during centrifugal dehydration is 2500 r / min to 4500 r / min, and the centrifugation time is 5 min to 30 min; the third step is to electrochemically treat the residual sludge for 2 h to 24 h at a temperature of 10°C to 90°C, an electrochemical action voltage of 5 V to 36 V, and an electrode spacing of 2 cm to 50 cm to obtain deeply dehydrated sludge.

[0029] The present invention is to contain a large amount of calcium ions (Ca 2+) Crude oil decalcification wastewater is used as a conditioning agent for the three refining muds to condition the three refining muds and improve the dewatering performance of the sludge; the conditioned sludge is mechanically dehydrated, and the dehydrated sludge is further treated with an electrochemical process to deeply dehydrate the remaining sludge. Chemical conditioning agents such as polyaluminium chloride (PAC), polyferric chloride (PFC), polyacrylamide (PAM) contained in the sludge are discharged together with the water phase, reducing the oil content and chlorine content in the sludge. The crude oil decalcification wastewater can also be recycled, reducing the cost of sludge treatment.

[0030] Among them, crude oil decalcification wastewater is a kind of wastewater containing a large amount of calcium ions (Ca 2+) produced by refineries to solve the adverse effects of high-calcium crude oil on refining processes, equipment and downstream product quality. 2+ ) is a highly polluted liquid waste. If it can be applied to deep sludge dewatering, it can achieve waste treatment.

[0031] Embodiment 2: As attached Figure 1 As shown, the method for deep dehydration of three kinds of mud in the refinery is carried out according to the following steps: the first step is to mix the bottom mud in the sludge sedimentation tank 1 with the crude oil decalcification wastewater, and then stir and condition to obtain the conditioned sludge, wherein the volume ratio of the bottom mud in the sludge sedimentation tank 1 to the crude oil decalcification wastewater is 0.5 or 1:1 or 2, the stirring and conditioning time is 30min or 120min, and the crude oil decalcification wastewater has a sodium ion content of 100mg / L or 2000mg / L, and a calcium ion content of 1000mg / L or 30000mg / L; the second step is to dehydrate the conditioned sludge by filter pressing or centrifugal dehydration. The method comprises the following steps: mechanically separating and dehydrating the sludge by water to obtain residual sludge with a moisture content of less than 75%, wherein the filtration pressure during filtration dehydration is 0.1MPa or 1.5MPa, the filtration time is 0.5h or 4h, the centrifuge speed during centrifugal dehydration is 2500r / min or 4500r / min, and the centrifugation time is 5min or 30min; the third step is to electrochemically treat the residual sludge for 2h to 24h at a temperature of 10°C or 90°C, an electrochemical action voltage of 5V or 36V, and an electrode spacing of 2cm or 50cm to obtain deeply dehydrated sludge.

[0032] Embodiment 3: As an optimization of the above embodiment, the bottom sludge in the sludge sedimentation tank 1 is the bottom sludge formed after the sludge produced by the oil separator, the flotation tank, and the A / O treatment unit enters the sludge sedimentation tank and settles.

[0033] Example 4: As an optimization of the above example, in the first step, the sodium ion content in the crude oil decalcification wastewater is 500 mg / L to 2000 mg / L, and the calcium ion content is 3000 mg / L to 30000 mg / L.

[0034] In the present invention, the calcium ions (Ca2+ ) Improves sludge dewatering performance by compressing the double electrical layer and adsorbing negative ions for electrical neutralization.

[0035] Example 5: As an optimization of the above example, the volume ratio of the sludge in the sludge sedimentation tank 1 to the crude oil decalcification wastewater is 0.5 to 1:1, and the stirring and conditioning time is 50 min to 90 min.

[0036] Example 6: As an optimization of the above example, the filtration pressure of the filtration dehydration is 0.5MPa to 1.0MPa, and the filtration time is 1h to 2h; or / and, the centrifuge speed of the centrifuge dehydration is 3000r / min to 4000r / min, and the centrifugation time is 10min to 20min.

[0037] Example 7: As an optimization of the above example, the conditions for electrochemical treatment of residual sludge are: temperature of 30°C to 60°C, electrochemical action voltage of 10V to 36V, plate spacing of 5cm to 20cm, and electrochemical treatment time of 8h to 16h.

[0038] In the electrochemical treatment of the present invention, calcium ions (Ca 2+ ) Strengthen the skeleton structure of sludge flocs and improve the compressibility of sludge, thereby improving the degree of sludge dewatering. The calcium ions (Ca 2+ ) and sodium ions (Na + ) and other salt substances constitute electrolytes, thereby improving the conductivity and dewatering performance of sludge in the electrochemical process.

[0039] Embodiment 8: As attached Figure 1 As shown, the device for implementing the method of deep dehydration of three sludges in a refinery comprises a sludge sedimentation tank 1, a sludge stirring tank 2, a mechanical separation device 3, an electrochemical device 14 and a power supply 15. A first sludge pipeline 5 is fixedly connected between the outlet of the sludge sedimentation tank 1 and the upper inlet of the sludge stirring tank 2. A first sludge pump 6 is fixedly installed on the first sludge pipeline 5. A crude oil decalcification wastewater pipeline 7 is fixedly connected to the first sludge pipeline 5 between the first sludge pump 6 and the sludge stirring tank 2. A first sludge pump 6 is fixedly installed on the first sludge pipeline 5 between the first sludge pump 6 and the sludge stirring tank 2. A first sludge pump 6 is fixedly connected to the first sludge pipeline 5 between the first sludge pump 6 and the sludge stirring tank 2. A first sludge pump 7 is fixedly connected to the first sludge pipeline 5 between the bottom outlet of the sludge stirring tank 2 and the inlet of the mechanical separation device 3. Second sludge pipeline 8, a second sludge pump 9 is fixedly installed on the second sludge pipeline 8, a third sludge pipeline 10 is fixedly connected between the sludge outlet of the mechanical separation equipment 3 and the sludge inlet of the electrochemical device 14, the water outlet of the mechanical separation equipment 3 is fixedly connected to the first sewage pipeline 11, the mud outlet of the electrochemical device 14 is fixedly connected to the fourth sludge pipeline 12, a wastewater circulation pipeline 13 is connected between the first sludge pipeline 5 between the crude oil decalcification wastewater pipeline 7 and the sludge stirring tank 2 and the water outlet of the electrochemical device 14, and the electrochemical device 14 is electrically connected to the power supply 15.

[0040] As required, the mechanical separation device 3 may be one of a plate and frame filter press, a chamber filter press and a disc centrifuge.

[0041] Embodiment 9: As attached Figure 1 As shown, as an optimization of the above embodiment, the electrochemical device 14 includes a reaction tank 16, an electrode 18 and a vacuum pump 4, a third sludge pipeline 10 is fixedly connected between the mud outlet of the mechanical separation equipment 3 and the mud inlet of the reaction tank 16, a fixed beam capable of fixing the electrode 18 is provided on the electrode 18, the electrode 18 is fixedly installed in the reaction tank 16 through the fixed beam, the electrode 18 is electrically connected to the power supply 15, a cavity 17 is provided at the bottom of the reaction tank 16, a wastewater circulation pipeline 13 is fixedly connected between the first sludge pipeline 5 between the crude oil decalcification wastewater pipeline 7 and the sludge stirring tank 2 and the bottom outlet of the cavity 17, and a vacuum pump 4 is fixedly installed on the wastewater circulation pipeline 13.

[0042] Embodiment 10: As an optimization of the above embodiment, the electrode 18 is an iron electrode, and the iron electrode includes an anode and a cathode, and the anode and the cathode are fixedly installed in the reaction tank 16 through a fixed crossbeam.

[0043] Embodiment 11: As an optimization of the above embodiment, a mesh screen with a mesh number of 50 to 200 is further provided at the bottom of the reaction tank 16.

[0044] Example 12: The bottom mud in the sludge sedimentation tank 1 with a water content of 95% and an oil content of 0.7% was mixed with sodium ions (Na + ) content is 100mg / L, calcium ion (Ca 2+ ) crude oil decalcified wastewater with a content of 1000 mg / L was stirred in a sludge stirring tank 2 at a volume ratio of 1:2 for 30 minutes. Then, a plate and frame filter press was used for filtration dehydration, with a filtration pressure of 0.5 MPa and a filtration time of 1 hour. After mud and water separation, the residual sludge obtained had a moisture content of 75%. Then, the residual sludge with a moisture content of 75% was placed in an electrochemical device 14, and acted for 2 hours under the conditions of a voltage of 5V, a treatment temperature of 30°C, and a plate spacing of 20 cm. The mesh number of the mesh screen was 50 meshes. After mud and water separation, the sludge had a moisture content of 29% and an oil content of 0.5%.

[0045] Example 13: The bottom mud in the sludge sedimentation tank 1 with a water content of 90% and an oil content of 3.5% was mixed with sodium ions (Na + ) content is 2000mg / L, calcium ion (Ca 2+) crude oil decalcified wastewater with a content of 30000 mg / L was stirred in a sludge stirring tank 2 at a volume ratio of 0.5:2 for 60 minutes. Then, a closed filter press was used for pressure filtration and dehydration, with a pressure of 1.5 MPa and a pressure filtration time of 4 hours. After mud and water separation, the residual sludge obtained had a moisture content of 70%. Then, the residual sludge with a moisture content of 70% was placed in an electrochemical device 14, and acted for 8 hours under the conditions of a voltage of 36V, a treatment temperature of 80°C, and a plate spacing of 2cm. The mesh number of the mesh screen was 200 meshes. After mud and water separation, the sludge had a moisture content of 20% and an oil content of 0.3%.

[0046] Example 14: The bottom mud in the sludge sedimentation tank 1 with a water content of 96% and an oil content of 3.8% was mixed with sodium ions (Na + ) content is 1000mg / L, calcium ion (Ca 2+ ) crude oil decalcified wastewater with a content of 20000 mg / L was stirred in a sludge stirring tank 2 at a volume ratio of 0.8:1 for 120 minutes. Then, a chamber filter press was used for filtration dehydration, with a filtration pressure of 0.8 MPa and a filtration time of 2 hours. After mud and water separation, the residual sludge obtained had a moisture content of 72%. Then, the residual sludge with a moisture content of 72% was placed in an electrochemical device 14, and acted for 4 hours under the conditions of a voltage of 12V, a treatment temperature of 50°C, and a plate spacing of 10 cm. The mesh number of the mesh screen was 100 meshes. After mud and water separation, the sludge had a moisture content of 26% and an oil content of 0.45%.

[0047] Example 15: The bottom mud in the sludge sedimentation tank 1 with a water content of 91% and an oil content of 1.3% was mixed with sodium ions (Na + ) content is 1000mg / L, calcium ion (Ca 2+ ) crude oil decalcified wastewater with a content of 20000mg / L was stirred in a sludge stirring tank 2 at a volume ratio of 1:1 for 90min. Then, a horizontal screw centrifuge was used for dehydration, the centrifuge speed was 2500r / min, the centrifugal time was 7min, and after mud and water separation, the residual sludge had a moisture content of 74%. Then, the residual sludge with a moisture content of 74% was placed in an electrochemical device 14, and acted for 6h under the conditions of a voltage of 24V, a treatment temperature of 60℃, and a plate spacing of 5cm. The mesh number of the mesh screen was 150 meshes. After mud and water separation, the sludge had a moisture content of 27%, and an oil content of 0.3%.

[0048] Example 16: The bottom mud in the sludge sedimentation tank 1 with a water content of 89% and an oil content of 2.7% was mixed with sodium ions (Na + ) content is 1500mg / L, calcium ion (Ca 2+) crude oil decalcified wastewater with a content of 10000mg / L was stirred in a sludge stirring tank 2 at a volume ratio of 0.5:1 for 120min. Then, a disc centrifuge was used for dehydration, the centrifuge speed was 4500r / min, the centrifugal time was 15min, and after mud and water separation, the residual sludge had a moisture content of 73%. Then, the residual sludge with a moisture content of 73% was placed in an electrochemical device 14, and acted for 3h under the conditions of a voltage of 12V, a treatment temperature of 50℃, and an electrode spacing of 8cm. The mesh number of the mesh screen was 80 meshes. After mud and water separation, the sludge had a moisture content of 28.5% and an oil content of 0.25%.

[0049] Example 17: The bottom mud in the sludge sedimentation tank 1 with a water content of 90% and an oil content of 1.0% was mixed with sodium ions (Na + ) content is 500mg / L, calcium ion (Ca 2+ ) crude oil decalcified wastewater with a content of 5000mg / L was stirred in a sludge stirring tank 2 at a volume ratio of 0.8:1 for 100min. Then, a horizontal screw centrifuge was used for dehydration, the centrifuge speed was 3500r / min, the centrifugal time was 10min, and after mud and water separation, the residual sludge had a moisture content of 74.5%. Then, the residual sludge with a moisture content of 74.5% was placed in an electrochemical device 14, and acted for 8h under the conditions of a voltage of 5V, a treatment temperature of 30℃, and a plate spacing of 4cm. The mesh number of the mesh screen was 170 meshes. After mud and water separation, the sludge had a moisture content of 26.5%, and an oil content of 0.35%.

[0050] Example 18: The bottom sludge in the sludge sedimentation tank 1 with a water content of 89% and an oil content of 1.5% was mixed with the recovered sodium ions (Na + ) content is 400mg / L, calcium ion (Ca 2+ ) content of 8000mg / L crude oil decalcified wastewater was stirred in the sludge stirring tank 2 at a volume ratio of 0.8:1 for 60min. Then, a disc centrifuge was used for dehydration, the centrifuge speed was 3000r / min, the centrifugal time was 13min, and after mud and water separation, the residual sludge had a moisture content of 74.1%. Then, the residual sludge with a moisture content of 74.1% was placed in the electrochemical device 14, and acted for 5h under the conditions of voltage of 6V, treatment temperature of 50℃, and plate spacing of 8cm. The mesh number of the mesh screen was 90 meshes. After mud and water separation, the sludge had a moisture content of 24.5%, and an oil content of 0.30%.

[0051] At the same time, the present invention has the following excellent effects:

[0052] (1) The crude oil decalcification wastewater used in the present invention is a polluted waste. 2+ ) and sodium ions (Na+ ) and other ingredients to condition the sludge, and act as an electrolyte in the sludge during the electrochemical process to improve the conductivity of the sludge and the dewatering performance of the sludge. This is the recycling of waste and the realization of the purpose of "treating waste with waste";

[0053] (2) The crude oil decalcification wastewater used in the present invention is itself a polluted waste, which does not require any cost or additional chemical conditioning agents, thus significantly reducing the cost of sludge treatment and disposal;

[0054] (3) After the refinery mud is conditioned by the crude oil decalcification wastewater used in the present invention, it is not necessary to use a cationic organic flocculant or an organic flocculant or lime before mechanical dehydration;

[0055] (4) After the dehydration method of the present invention is used to treat the three refining muds, the moisture content of the mud cake can be reduced to below 65% after filter pressing dehydration, and the moisture content of the mud cake can be reduced to below 75% after centrifugal dehydration;

[0056] (5) After the three refining muds are electrochemically treated in the deep dehydration method of the present invention, the moisture content of the mud cake can be reduced to below 30%, and the oil content can be reduced to below 0.5%;

[0057] (6) After the three refining muds are treated by the deep dehydration method of the present invention, the chemical conditioning agents such as polyaluminium chloride (PAC), polyferric chloride (PFC), polyacrylamide (PAM) in the sludge are discharged together with the water phase, thereby reducing the chlorine content in the sludge.

[0058] In summary, the present invention has the characteristics of simple operation and low energy consumption. It can deeply dehydrate the sludge while improving the dewatering performance of the sludge. It can effectively reduce the use of chemical conditioners in the sludge dewatering process, reduce the sludge treatment cost, and achieve the purpose of treating waste with waste.

[0059] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A method for deep dehydration of refinery three-sludges, characterized in that it is carried out according to the following steps: First step, mix the bottom sludge in the sludge sedimentation tank with the crude oil decalcification wastewater, and then stir and condition to obtain the conditioned sludge. Among them, the volume ratio of the bottom sludge in the sludge sedimentation tank to the crude oil decalcification wastewater is 0.5 to 1:1 to 2, the stirring and conditioning time is 30 min to 120 min. In the crude oil decalcification wastewater, the sodium ion content is 100 mg / L to 2000 mg / L, and the calcium ion content is 1000 mg / L to 30000 mg / L; Second step, mechanically separate and dehydrate the conditioned sludge by means of pressure filtration dehydration or centrifugal dehydration to obtain the remaining sludge with a moisture content below 75%. Among them, when pressure filtration dehydration is carried out, the pressure filtration pressure is 0.1 MPa to 1.5 MPa, the pressure filtration time is 0.5 h to 4 h, when centrifugal dehydration is carried out, the centrifuge speed is 2500 r / min to 4500 r / min, and the centrifugation time is 5 min to 30 min; Third step, carry out electrochemical treatment on the remaining sludge for 2 h to 24 h under the conditions of a temperature of 10 °C to 90 °C, an electrochemical action voltage of 5 V to 36 V, and a plate spacing of 2 cm to 50 cm to obtain the deeply dehydrated sludge.

2. The method for deep dehydration of refinery three-sludges according to claim 1, characterized in that the bottom sludge in the sludge sedimentation tank is the bottom sludge formed after the sludge generated by the oil separation tank, the flotation tank, and the A / O treatment unit enters the sludge sedimentation tank and settles.

3. The method for deep dehydration of refinery three-sludges according to claim 1 or 2, characterized in that in the first step, in the crude oil decalcification wastewater, the sodium ion content is 500 mg / L to 2000 mg / L, and the calcium ion content is 3000 mg / L to 30000 mg / L.

4. The method for deep dehydration of refinery three-sludges according to claim 3, characterized in that the volume ratio of the bottom sludge in the sludge sedimentation tank to the crude oil decalcification wastewater is 0.5 to 1:1, and the stirring and conditioning time is 50 min to 90 min.

5. The method for deep dehydration of refinery three-sludges according to claim 1 or 2 or 4, characterized in that characterized in that when pressure filtration dehydration is carried out, the pressure filtration pressure is 0.5 MPa to 1.0 MPa, the pressure filtration time is 1 h to 2 h, when centrifugal dehydration is carried out, the centrifuge speed is 3000 r / min to 4000 r / min, and the centrifugation time is 10 min to 20 min.

6. The method for deep dehydration of refinery three-sludges according to claim 5, characterized in that the conditions for electrochemical treatment of the remaining sludge are a temperature of 30 °C to 60 °C, an electrochemical action voltage of 10 V to 36 V, a plate spacing of 5 cm to 20 cm, and the electrochemical treatment time is 8 h to 16 h.

7. A device for implementing the method for deep dehydration of refinery three-sludges according to any one of claims 1 to 6, characterized in that It includes a sludge sedimentation tank, a sludge stirring tank, a mechanical separation device, an electrochemical device and a power supply. There is a first sludge pipeline fixedly connected between the outlet of the sludge sedimentation tank and the upper inlet of the sludge stirring tank. A first sludge pump is fixedly installed on the first sludge pipeline. An oil-decalcifying wastewater pipeline is fixedly connected to the first sludge pipeline between the first sludge pump and the sludge stirring tank. A second sludge pipeline is fixedly connected between the bottom outlet of the sludge stirring tank and the inlet of the mechanical separation device. A second sludge pump is fixedly installed on the second sludge pipeline. A third sludge pipeline is fixedly connected between the sludge outlet of the mechanical separation device and the sludge inlet of the electrochemical device. The water outlet of the mechanical separation device is fixedly connected to a first sewage pipeline. The sludge outlet of the electrochemical device is fixedly connected to a fourth sludge pipeline. A wastewater circulation pipeline is connected between the first sludge pipeline between the oil-decalcifying wastewater pipeline and the sludge stirring tank and the water outlet of the electrochemical device. The electrochemical device is electrically connected to the power supply.

8. The device according to claim 7, wherein the electrochemical device includes a reaction tank, electrodes and a vacuum pump. A third sludge pipeline is fixedly connected between the sludge outlet of the mechanical separation device and the sludge inlet of the reaction tank. A fixed crossbeam for fixing the electrodes is provided on the electrodes. The electrodes are fixedly installed in the reaction tank through the fixed crossbeam. The electrodes are electrically connected to the power supply. A cavity is provided at the bottom of the reaction tank. A wastewater circulation pipeline is fixedly connected between the first sludge pipeline between the oil-decalcifying wastewater pipeline and the sludge stirring tank and the bottom outlet of the cavity. A vacuum pump is fixedly installed on the wastewater circulation pipeline.

9. The device according to claim 8, wherein the electrodes are iron electrodes. The iron electrodes include an anode and a cathode. Both the anode and the cathode are fixedly installed in the reaction tank through the fixed crossbeam.

10. The device according to claim 7 or 8, wherein a mesh sieve plate with a mesh size of 50 to 200 meshes is further provided at the bottom of the reaction tank.

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