Pretreatment device for refinery wastewater

Abstract

The utility model discloses a pretreatment device of refinery waste water, including first treatment pond, second treatment pond, third treatment pond and fourth treatment pond, wherein the first treatment pond is homogeneous regulation pond including at least one first stirring device, the first treatment pond includes annular groove pond, the hydraulic retention time of homogeneous regulation pond is 36-48h, and the second treatment pond includes the first stirring device and the second stirring device. The longer the time is, the more thorough the separation of water, oil and mud is; the second treatment tank is an oil separation tank and comprises at least one second stirring device, and the second treatment tank comprises an annular groove-shaped tank; the third treatment pond and the fourth treatment pond form an integrated reaction sedimentation pond, the third treatment pond is a reaction pond, and the fourth treatment pond is a sedimentation pond. The oil refining wastewater pretreatment device disclosed by the utility model is suitable for treating various oil refining and petrochemical wastewater, and better oil-water separation is realized; the discharged sludge is better formed; and the problem of large peculiar smell is avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of treatment device for oil refining wastewater, in particular to a kind of oil refining wastewater pretreatment device, belong to oil refining wastewater treatment technical field. BACKGROUND

[0002] Oil refining wastewater is a kind of industrial wastewater with large water volume and high treatment difficulty. The difficulty of treating this kind of wastewater lies in that oil and silt are contained in the wastewater, forming a relatively stable "water-in-oil" and "oil-in-silt" state. Therefore, the key of oil refining wastewater pretreatment is to separate oil, water and silt into three phases, and then dispose them respectively.

[0003] The conventional treatment process of oil refining wastewater is the old three-processes of "oil separation + air flotation + biochemical treatment". First, the oil separation unit. The earliest commonly used was a horizontal flow oil separation tank, which had a large land occupation area, equipment maintenance difficulty and strong odor. Later, it was gradually replaced by the "tank-in-tank" process. The tank-in-tank equipment is a closed container composed of two tanks. The wastewater first enters the hydrocyclone separation zone of the inner tank, and the different centrifugal force fields generated by the different densities of oil and water and the secondary upflow liquid flow generated in the cyclone are used to separate the immiscible oil and water. In addition, it can also produce good sedimentation effect on the solid phase in the liquid, achieving the purpose of three-phase separation of wastewater. The oil phase after hydrocyclone separation floats to the top of the inner tank, and the oil is discharged by the automatic skimming device. The sediment is discharged from the tank bottom, and the oil-removed wastewater is discharged through the evenly distributed siphon connecting pipe around the outer tank, and further reduces the oil concentration of the effluent through the pre-set water distribution baffle, collision aggregation and other separation processes in the outer tank. Second, the air flotation unit. Generally, two-stage air flotation treatment is adopted. The first stage adopts vortex cavity air flotation, and the second stage adopts dissolved air flotation.

[0004] Generally speaking, the existing oil refining wastewater pretreatment methods described above have the following problems:

[0005] (1) Incomplete oil-water separation, not resistant to impact, and the oil content of the effluent of the second-stage air flotation often exceeds 20 mg / L, resulting in a decrease in the efficiency of subsequent biochemical treatment and exceeding the standard of the effluent;

[0006] (2) The oil content of the sludge discharged by the tank-in-tank and the sludge discharged by the air flotation is high, and the treatment difficulty is great. Currently, a centrifugal dehydrator or a stacked screw dehydrator is generally used, and a large amount of coagulant or inorganic auxiliary material needs to be added, otherwise the moisture content of the sludge is high and the sludge is not formed;

[0007] (3) The air flotation sludge is entrained with a large amount of water, and a sludge thickening tank generally needs to be set up, and the pressure of sludge dewatering is large;

[0008] (4) The produced floating oil has high water content and contains many solid impurities, and cannot be utilized;

[0009] (5) The odor problem of the wastewater treatment plant is difficult to solve. SUMMARY

[0010] The technical problem to be solved by the utility model lies in providing a pretreatment device for oil refining wastewater, which solves the problems of incomplete separation and strong odor of the existing oil refining wastewater treatment device.

[0011] The technical problem to be solved by the utility model is solved by the following technical scheme:

[0012] The utility model provides a pretreatment device for oil refining wastewater, underwater propellers are installed in the homogenizing adjusting pool (the first treatment pool 100) and the oil separation pool (the second treatment pool 200) in the pretreatment device in the embodiment, flow of the wastewater in the pool is caused by mechanical stirring, the water, mud and oil in the wastewater are separated by the shearing action of hydraulic stirring, small oil droplets in the wastewater collide and combine to form small oil droplets, which float to the upper layer of the pool, because of the difference in flow rate between the water layer and the oil layer, the water and the mud in the oil layer are separated from the oil layer, and the water content and the solid content of the oil in the oil layer are further reduced;

[0013] Specifically, the pretreatment device comprises a first treatment pool, a second treatment pool, a third treatment pool and a fourth treatment pool, wherein:

[0014] The first treatment pool is a homogenizing adjusting pool and comprises at least one first stirring device, wherein the first treatment pool comprises a ring ditch-shaped pool, because the water quantity of the oil refining wastewater is large, the ring ditch-shaped pool is better, the investment cost is low, the stirring effect of the underwater propeller is better, the hydraulic retention time of the homogenizing adjusting pool is 36-48h, and the longer the time is, the more complete the separation of the water, oil and mud is;

[0015] The second treatment pool is an oil separation pool and comprises at least one second stirring device, wherein the second treatment pool comprises a ring ditch-shaped pool;

[0016] The third treatment pool and the fourth treatment pool constitute an integrated reaction and precipitation pool, wherein:

[0017] The third treatment pool is a reaction pool, and the fourth treatment pool is a precipitation pool;

[0018] The third treatment pool comprises at least one third stirring device, and the fourth treatment pool comprises at least one fourth stirring device.

[0019] As a preferred technical scheme of the utility model, the third treatment pool and the fourth treatment pool are concentric circular pools, wherein the outer ring is the third treatment pool, and the inner ring is the fourth treatment pool.

[0020] As a preferred technical scheme of the utility model, the first treatment pool, the second treatment pool and the third treatment pool are all equipped with oil collectors, and the oil collectors are connected to the crude oil refining section.

[0021] As a preferred technical scheme of the utility model, the hydraulic retention time of the first treatment pool is 36-48h, the total power density of the first stirring device in the first treatment pool is 1.0-2.0kW / m 3 ;

[0022] The hydraulic retention time of the second treatment pool is 18-24h, and the total power density of the second stirring device in the second treatment pool is 1.0-2.0kW / m 3 ;

[0023] The hydraulic retention time of the third treatment pool is 2-4h, and the total power density of the third stirring device in the third treatment pool is 0.5-1.5kW / m 3 ;

[0024] The surface load of the fourth treatment pool is 0.7-1.0m3 / m·h, wherein,

[0025] Polymeric ferric sulfate and anionic polyacrylamide are added in the fourth treatment pool.

[0026] As a preferred technical scheme of the utility model, the first treatment pool and the second treatment pool are both equipped with inclined plate fillers, wherein,

[0027] The length of the inclined plate filler is 0.5-1.5m, and the inclination angle is 50°-70°.

[0028] As a preferred technical scheme of the utility model, the first treatment pool and the second treatment pool are both equipped with stainless steel water collectors, wherein,

[0029] The water collector is installed below the inclined plate filler.

[0030] As a preferred technical scheme of the utility model, the first stirring device, the second stirring device and the third stirring device all include at least one underwater propeller.

[0031] The beneficial effects of this utility model are as follows: The oil refining wastewater pretreatment device of this utility model is suitable for the treatment of various oil refining and petrochemical wastewater, achieving better oil-water separation; the discharged sludge is better formed; the problem of strong odor is avoided; the concentration of petroleum in the effluent of the sedimentation tank is stable below 20 mg / L, and SS is below 100 mg / L; the COD of the effluent from the subsequent biological treatment system can reach below 40 mg / L; the sludge dewatering system uses a plate and frame membrane filter press for sludge dewatering, and the moisture content of the sludge cake after dewatering is below 60%, and the moisture content of the recovered oil is below 10%, which can be returned to the workshop for refining; it has the advantages of wide applicability, low investment, stable treatment effect, and simple and reliable operation. Attached Figure Description

[0032] Figure 1 This is one of the structural schematic diagrams of this utility model;

[0033] Figure 2 This is the second structural schematic diagram of the present invention;

[0034] In the diagram: 100, first treatment tank; 101, first stirring device; 200, second treatment tank; 201, second stirring device; 300, third treatment tank; 301, third stirring device; 400, fourth treatment tank; 401, fourth stirring device. Detailed Implementation

[0035] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0036] Example

[0037] like Figures 1-2 As shown, this embodiment provides a pretreatment device for oil refinery wastewater. In this embodiment, the pretreatment device is equipped with underwater propellers in a homogenization tank (first treatment tank 100) and an oil separator (second treatment tank 200). The mechanical stirring action causes the wastewater in the tank to flow, and the shearing action of the hydraulic stirring separates the water, mud, and oil in the wastewater. At the same time, small oil droplets in the wastewater collide and combine with each other to form small oil droplets that float to the upper layer of the tank. Due to the difference in flow velocity between the water layer and the oil layer, the water and mud in the oil layer are separated from the oil layer, further reducing the water content and solid content of the oil in the oil layer.

[0038] Specifically, the pretreatment device includes a first treatment tank 100, a second treatment tank 200, a third treatment tank 300, and a fourth treatment tank 400, wherein:

[0039] The first treatment tank 100, which is a homogenizing tank, comprises at least one first stirring device 101, wherein the first treatment tank 100 comprises a ring-gutter-shaped tank, because the water quantity of the oil refining wastewater is large, the ring-gutter-shaped tank is better, the investment cost is low, and the stirring effect of the underwater propeller is better; the hydraulic retention time of the homogenizing tank is 36-48h, the longer the time is, the more thorough the separation of water, oil and mud is; preferably, the position of the water inlet point of the homogenizing tank is not less than 1.5m below the water surface, and the direction of the water inlet and the direction of the water flow are consistent, mainly to avoid the disturbance of the water inlet to the oil layer, and to make the quality of the oil layer more stable;

[0040] The second treatment tank 200, which is an oil separation tank, comprises at least one second stirring device 201, wherein the second treatment tank 200 comprises a ring-gutter-shaped tank; the position of the water inlet point of the oil separation tank is not less than 1.5m below the water surface, and the direction of the water inlet and the direction of the water flow are consistent, mainly to avoid the disturbance of the water inlet to the oil layer, and to make the quality of the oil layer more stable. In another preferable embodiment of the utility model, in order to improve the oil separation effect of the oil separation tank, the oil separation tank adds a high molecular flocculating agent, the cationic polyacrylamide is the best flocculating agent, and the addition amount of the polyacrylamide is 2-5mg / L;

[0041] The third treatment tank 300 and the fourth treatment tank 400 constitute an integrated reaction and precipitation tank, wherein the third treatment tank 300 is a reaction tank, and the fourth treatment tank 400 is a precipitation tank; the third treatment tank 300 comprises at least one third stirring device 301, and the fourth treatment tank 400 comprises at least one fourth stirring device 401.

[0042] Specifically, the third treatment pool 300 and the fourth treatment pool 400 are concentric circular pools, wherein the outer ring is the third treatment pool 300 and the inner ring is the fourth treatment pool 400. In the embodiment, the first stirring device 101, the second stirring device 201 and the third stirring device 301 each include at least one underwater propeller and can realize oil, mud and water separation; more specifically, the oil refining wastewater enters the homogenizing adjustment pool (the first treatment pool 100), the homogenizing adjustment pool is provided with an underwater propeller (i.e. the first stirring device 101), and the oil, mud and water are separated through the stirring of the underwater propeller, which is the first-stage oil separation; then the oil separation pool (the second treatment pool 200) is entered, and a flocculating agent is added to the oil separation pool, the oil separation pool is provided with an underwater propeller (i.e. the second stirring device 201), and the oil, mud and water are separated through the stirring of the underwater propeller, which is the second-stage oil separation; the water from the oil separation pool enters the integrated reaction and precipitation pool (which is composed of the third treatment pool 300 and the fourth treatment pool 400), a flocculating agent is added to the reaction pool (i.e. the third treatment pool 300), and the reaction pool is provided with an underwater propeller (i.e. the third stirring device 301), and the oil, mud and water are separated through the stirring of the underwater propeller, which is the third-stage oil separation; then the water from the reaction pool enters the precipitation pool (i.e. the fourth treatment pool 400) for the final separation of mud and water, the water from the precipitation pool enters the subsequent biological treatment system, and the sludge from the bottom of the precipitation pool is subjected to sludge dewatering by using a plate-frame diaphragm filter press, and the water content of the dewatered mud cake is less than 60%.

[0043] The first treatment pool 100, the second treatment pool 200 and the third treatment pool 300 are each provided with an oil collector which is connected to the crude oil refining section.

[0044] Specifically, in the embodiment, the first treatment pool 100, the second treatment pool 200, the third treatment pool 300 and the fourth treatment pool 400 are configured as follows:

[0045] The hydraulic retention time of the first treatment pool 100 is 36-48h, and the total power density of the first stirring device 101 in the first treatment pool 100 is 1.0-2.0kW / 1000m 3 ;

[0046] The hydraulic retention time of the second treatment pool 200 is 18-24h, and the total power density of the second stirring device 201 in the second treatment pool 200 is 1.0-2.0kW / 1000m 3 ;

[0047] The hydraulic retention time of the third treatment pool 300 is 2-4h, and the total power density of the third stirring device 301 in the third treatment pool 300 is 0.5-1.5kW / 1000m 3 ;

[0048] The surface load of the fourth treatment tank 400 is 0.7-1.0 m3 / m2·h, and polymeric ferric sulfate and anionic polyacrylamide are added in the fourth treatment tank 400.

[0049] In another preferable embodiment of the present application, the inclined plate fillers are installed in the first treatment tank 100 and the second treatment tank 200, wherein the length of the inclined plate filler is 0.5-1.5 meters, and the inclination angle is 50°-70°, for example, the specification of the inclined plate filler is φ100, the length of the filler is 1.0 meter, and the installation inclination angle of the filler is 60°. The inclined plate filler can better separate oil and promote the coagulation of small oil droplets.

[0050] The first treatment tank 100 and the second treatment tank 200 are both installed with a stainless steel water collecting pipe, and the water collecting pipe is installed below the inclined plate filler. Specifically, in the present embodiment, the water collecting pipe of the homogenizing tank and the oil separation tank is made of 304 stainless steel, the water collecting pipe is installed at the lower part of the inclined plate filler, the branch pipe flow rate of the water collecting pipe is 0.2-0.4 m / s, and the main pipe flow rate of the water collecting pipe is 0.3-0.5 m / s. The water outlet of the oil separation tank enters the reaction and precipitation tank, the reaction and precipitation tank is an integrated tank and is composed of two concentric circular tanks, the outer ring is a reaction tank, and the inner ring is a precipitation tank. The hydraulic retention time of the reaction tank is 2-4 h, and the surface load of the precipitation tank is 0.7-1.0 m3 / (m2·h). In another preferable embodiment of the present application, polymeric ferric sulfate and anionic polyacrylamide are added in the reaction tank, the polymeric ferric sulfate can remove sulfur ions in the refinery wastewater, the sludge formed by the polymeric ferric sulfate has a fast precipitation speed, the moisture content of the sludge cake after dewatering is low, the dosage of the polymeric ferric sulfate is 200-400 mg / L, the anionic polyacrylamide is added as a flocculant, and the dosage of the anionic polyacrylamide is 2-5 mg / L.

[0051] Specifically, the following is an operation example according to the scheme in the present embodiment;

[0052] A centralized wastewater treatment plant of a certain petroleum refining enterprise in Dongying City, Shandong Province, mainly includes electric desalting wastewater, oil tank cutting water, cracking, stripping, rectification, reforming wastewater, butyl octanol production wastewater, concentrated brine, circulating water drainage, initial rainwater, domestic sewage, etc. The design scale of the wastewater treatment plant is 2x800 m 3 / h, and is divided into a high-salt wastewater treatment system and a low-salt treatment system according to the amount of salt content. The treatment scale of the pretreatment system is 500 m 3 / h, the influent COD is 600-1000 mg / L, the oil content is 200-500 mg / L, and the wastewater treatment process is "homogenizing tank + oil separation tank + reaction and precipitation tank + A / O + coagulation and precipitation tank + sand filtration + ultrafiltration reverse osmosis". The device used in the pretreatment is as shown in Figure 1 .

[0053] The homogenizing tank in the example has a size of 112 m x 24 m x 6 m, an effective volume of 14000 m 3 , a hydraulic retention time of 28 h, 4 underwater propellers are installed, each with a power of 3.1 kW, and the power density of the homogenizing tank stirring is 0.88 kW / 1000 m 3 The size of the water collecting pipe is a DN600 stainless steel pipe, the flow rate of the main pipe of the water collecting pipe is 0.49 m / s, the size of the branch pipe of the water collecting pipe is DN250, and the flow rate of the branch pipe of the water collecting pipe is 0.35 m / s.

[0054] The size of the homogenizing tank is 112 m x 12 m x 6 m, the effective volume is 7000 m3, the hydraulic retention time is 28 h, 2 underwater propellers are installed, each with a power of 3.1 kW, and the power density of the homogenizing tank stirring is 0.88 kW / 1000 m 3 The size of the water collecting pipe is a DN600 stainless steel pipe, the flow rate of the main pipe of the water collecting pipe is 0.49 m / s, the size of the branch pipe of the water collecting pipe is DN250, and the flow rate of the branch pipe of the water collecting pipe is 0.35 m / s. Polyacrylamide is added to the oil separation tank, and the dosage of polyacrylamide is 3 mg / L.

[0055] The size of the reaction and precipitation tank is D34 m x 6 m, the size of the precipitation tank is D28 m x 6 m, the effective volume of the reaction tank is 2200 m 3 , the reaction time is 4.4 h, 2 underwater propellers are installed, each with a power of 1.25 kW, and the power density of the reaction tank stirring is 1.14 kW / 1000 m 3 The surface load of the precipitation tank is 0.81 m 3 / (m2·h), polymeric ferric sulfate and polyacrylamide are added to the reaction tank, the dosage of polymeric ferric sulfate is 300 mg / L, and the dosage of polyacrylamide is 3 mg / L.

[0056] The concentration of petroleum in the effluent of the homogenizing tank is 40-60 mg / L, the concentration of petroleum in the effluent of the oil separation tank is 15-30 mg / L, the concentration of petroleum in the effluent of the reaction and precipitation tank is 5-10 mg / L, after treatment by the A / O system, the COD concentration in the effluent is 20-40 mg / L, and no petroleum substance is detected.

[0057] The oil refining wastewater pretreatment device is suitable for treatment of various oil refining and petrochemical wastewater, realizes better oil-water separation, better shaping of discharged sludge, avoids the problem of large odor, the effluent oil concentration of the sedimentation tank is stably below 20mg / L, SS is below 100mg / L, the effluent COD of the subsequent biological treatment system can be below 40mg / L, the sludge dewatering system adopts a plate-frame diaphragm filter press to dewater the sludge, the water content of the mud cake after dewatering is below 60%, the water content of the recovered oil is below 10%, and the recovered oil can be returned to the workshop for re-refining; the device has the advantages of wide applicability, low investment, stable treatment effect, simple and reliable operation, etc.

[0058] The basic principle, main features and advantages of the utility model are shown and described above. Those skilled in the art should understand that the utility model is not limited by the above-mentioned embodiments, and various changes and improvements can be made without departing from the spirit and scope of the utility model, and these changes and improvements all fall within the scope of the utility model claimed. The scope of the utility model claimed is defined by the appended claims and their equivalents.

Claims

1. A device for pretreatment of refinery wastewater, characterized in that It comprises a first treatment pool (100), a second treatment pool (200), a third treatment pool (300) and a fourth treatment pool (400), wherein: The first treatment pool (100) is a homogenizing pool, comprising at least one first stirring device (101), wherein the first treatment pool (100) comprises a ring-gutter-shaped pool; The second treatment pool (200) is an oil separation pool, comprising at least one second stirring device (201), wherein the second treatment pool (200) comprises a ring-gutter-shaped pool; The third treatment pool (300) and the fourth treatment pool (400) constitute an integrated reaction and precipitation pool, wherein, The third treatment pool (300) is a reaction pool, and the fourth treatment pool (400) is a precipitation pool; The third treatment pool (300) comprises at least one third stirring device (301), and the fourth treatment pool (400) comprises at least one fourth stirring device (401).

2. A device for the pretreatment of refinery wastewater according to claim 1, characterized in that, The third treatment pool (300) and the fourth treatment pool (400) are concentric circular pools, wherein the outer ring is the third treatment pool (300), and the inner ring is the fourth treatment pool (400).

3. The device for pre-treatment of refinery wastewater according to claim 1, characterized in that, An oil collector is installed in each of the first treatment pool (100), the second treatment pool (200) and the third treatment pool (300), and the oil collector is connected to a crude oil refining section.

4. The apparatus for the pretreatment of refinery wastewater according to claim 1, characterized in that, The hydraulic retention time of the first treatment tank (100) is 36-48h, and the total power density of the first stirring device (101) therein is 1.0-2.0kW / 1000m 3 ; The hydraulic retention time of the second treatment tank (200) is 18-24h, and the total power density of the second stirring device (201) therein is 1.0-2.0kW / 1000m 3 ; The hydraulic retention time of the third treatment tank (300) is 2-4h, and the total power density of the third stirring device (301) in the period is 0.5-1.5kW / 1000m 3 ; The surface load of the fourth treatment pool (400) is 0.7-1.0 m3 / (m2·h), wherein, Polymeric ferric sulfate and anionic polyacrylamide are added to the fourth treatment pool (400).

5. The apparatus for the pretreatment of refinery wastewater according to claim 1, wherein Inclined plate fillers are installed in the first treatment pool (100) and the second treatment pool (200), wherein, The length of the inclined plate filler is 0.5-1.5 meters, and the inclination angle is 50°-70°.

6. A device for the pretreatment of refinery wastewater according to claim 5, characterized in that Stainless steel water collectors are installed in the first treatment pool (100) and the second treatment pool (200), wherein, The water collector is installed below the inclined plate filler.

7. The device for pre-treatment of refinery wastewater according to claim 1, characterized in that, The first stirring device (101), the second stirring device (201) and the third stirring device (301) each comprise at least one underwater propeller.

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