Oil removal system for oily wastewater

Abstract

According to the technical scheme, the oil removal system is characterized by comprising a gravity oil removal tank, a DAF air flotation device and a dense medium precipitation device which are sequentially communicated, and further comprising a sludge concentration tank, the sludge concentration tank is provided with a first pipe for collecting slag discharged by the gravity oil removal tank and a second pipe for collecting dross of the DAF air flotation device, and the first pipe is provided with a first pipe for collecting the dross of the DAF air flotation device. The sludge concentration tank is provided with a third pipe for collecting sludge of the dense medium precipitation device; the sludge thickening tank is connected with a stacked screw dehydrator; the gravity oil removal tank is provided with a first floating oil collector, and the DAF air floatation device is provided with a second floating oil collector; the second floating oil collector is provided with a floating oil suction part, the floating oil suction part is connected with an oil suction pipe, the oil suction pipe is provided with a rotary filtering assembly for pouring scum into the second pipe, the stacked screw dehydrator is adopted to rapidly dehydrate the sludge collected at all levels, and the recovery efficiency of the dewatered sludge is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of waste liquid treatment, and more specifically, to an oil-containing wastewater deoiling system. Background Art

[0002] Scum with oily components is generally difficult to biodegrade. If the wastewater contains oily substances, it is necessary to pre-treat the oily substances in the wastewater first to prevent the oily substances from entering the biochemical treatment unit.

[0003] The existing commonly used treatment processes for oily wastewater include: the combined use of gravity separation, flotation and heavy medium sedimentation.

[0004] For example, in the prior art, a centrifugal gravity oil removal filter device with the announcement number CN214913748U clearly describes the oil removal method of gravity separation.

[0005] For example, the oily wastewater integrated treatment device with the prior art publication number CN203333410U clearly records the oil removal method of air flotation (DAF), and cooperates with the oil collector to collect the scum. The mobile industrial wastewater oil collector with the publication number CN209583705U discloses an existing oil collector.

[0006] For example, in the prior art, a high-efficiency water treatment device and a water treatment method with the announcement number CN103739124B clearly record that filtered water is obtained after heavy medium precipitation.

[0007] However, in the prior art, after the oily wastewater is subjected to gravity separation, flotation and heavy medium sedimentation in sequence, some water still remains in the scum and sludge, and the volume of the sludge is large. In order to reduce the amount of sludge and effectively utilize resources, the concentrated sludge is usually dehydrated by exposure to the sun. However, this method is inefficient and may cause sludge dehydration failure on rainy days. Utility Model Content

[0008] The purpose of the utility model is to provide an oil-containing wastewater deoiling system, which adopts a screw press dewatering machine to quickly dewater the sludge collected at each level, thereby improving the recovery efficiency of the dewatered sludge.

[0009] The above technical objectives of the present invention are achieved through the following technical solutions:

[0010] A system for removing oil from oily wastewater comprises a gravity oil removal tank, a DAF flotation device and a heavy medium sedimentation device connected in sequence, and also comprises a sludge thickening tank. The sludge thickening tank is provided with a No. 1 pipe for collecting slag discharged from the gravity oil removal tank, a No. 2 pipe for collecting scum from the DAF flotation device, and a No. 3 pipe for collecting sludge from the heavy medium sedimentation device; the sludge thickening tank is connected to a screw press dewatering machine; the gravity oil removal tank is provided with a No. 1 floating oil collector, and the DAF flotation device is provided with a No. 2 floating oil collector; the No. 2 floating oil collector is provided with a floating oil suction piece, which is connected to an oil suction pipe, and the oil suction pipe is provided with a rotary filter assembly for pouring scum into the No. 2 pipe.

[0011] Preferably, the oil suction pipe includes a vertical hard pipe, which includes an upper pipe, a middle pipe and a lower pipe. The middle pipe connects the upper pipe and the lower pipe. The upper pipe and the lower pipe are both provided with a concave connecting rod. The rotary filter assembly includes a filter screen fixed in the middle pipe and a rotating arm connected to the outer wall of the middle pipe. The rotating arm is connected to a rotating shaft, which is connected to a bracket, and the bracket is connected to a motor that drives the rotating shaft to rotate horizontally to bring the middle pipe to separate the upper pipe and the lower pipe.

[0012] Preferably, the rotating arm and the middle tube are rotationally connected, and the rotating arm is provided with a No. 2 motor for driving the middle tube to rotate vertically; the inlet of the No. 2 tube is opened vertically upward, and the middle tube between the upper tube and the lower tube is located directly above the No. 2 tube, and the inlet diameter of the No. 2 tube is larger than the diameter of the middle tube.

[0013] Preferably, a blower for blowing air downward is provided just above the No. 2 pipe, and the blower is located above the middle pipe.

[0014] Preferably, the outlet end of the upper tube is provided with a conical ring opening, the conical ring opening is located on the inner wall of the upper tube, the lower opening of the conical ring opening faces the middle tube, and the lower edge of the conical ring opening is located inside the upper tube.

[0015] Preferably, the upper and lower edges of the middle tube are both sealed with rubber rings.

[0016] Preferably, the filter mesh is a stainless steel mesh.

[0017] Preferably, the heavy medium sedimentation device is provided with a drain pipe, which is connected to the water purification component.

[0018] In summary, the present invention has the following beneficial effects:

[0019] (1) In this design, the sludge after oil removal and water purification in both the gravity oil removal tank and the heavy medium sedimentation device will settle, and the sludge collection is relatively convenient; the scum in the DAF flotation device is floating and is absorbed together with the oil stains, so a fast rotary filter assembly is required to collect the scum in the floating oil and then merge it into the sludge pool. This design uses a rotating filter to filter and collect the scum in the oil stains and then quickly dump it into the No. 2 pipe, realizing the rapid recovery of the scum, thereby improving the overall sludge dewatering efficiency;

[0020] The spiral stacking sludge dewatering machine is a new type of solid-liquid separation equipment that uses the screw extrusion principle. It uses the powerful extrusion force generated by the changes in the screw diameter and pitch, as well as the tiny gap between the floating ring and the fixed ring, to achieve extrusion dehydration of the sludge. Therefore, the spiral stacking sludge dewatering machine can quickly dehydrate the deoiled sludge in the wastewater, and its efficiency is much higher than the sludge drying dehydration.

[0021] (2) The rotary filter assembly can quickly separate the scum. In addition, it prevents the scum from entering the oil separation main unit of the No. 2 oil collector, thereby reducing the wear of the oil separation main unit caused by the scum and improving the service life of the No. 2 oil collector.

[0022] (3) When the filter is turned over, some of the scum will stick to the filter. At this time, the air flow from above can blow as much of the scum on the filter as possible into the No. 2 pipe below.

[0023] (4) The conical ring is designed to prevent the oil from splashing outwards as much as possible when it flows downwards. After the middle tube is separated, a small amount of oil will flow between the upper and lower tubes. If there is no conical ring, the oil will easily drip onto the edge of the lower tube, causing leakage.

[0024] (5) The rubber ring has a sealing property, which makes it difficult for the hard tube to leak when oil is injected into it. Secondly, it has elasticity, so there will be no rigid collision when the middle tube moves between the upper tube and the lower tube.

[0025] (6) The water purification component can be a special filter component composed of inorganic membrane and organic membrane, or it can be a reverse osmosis membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1. It is a schematic structural diagram of an oily wastewater deoiling system according to an embodiment;

[0027] Figure 2 2. This is a schematic diagram of a state in which the middle tube in the embodiment is horizontally rotated to form the upper tube and the lower tube;

[0028] Figure 3 is a schematic diagram of a rotary filter assembly in an embodiment;

[0029] Figure 4 yes Figure 3 A magnified view of part A in FIG;

[0030] Figure 5 yes Figure 3 Enlarged view of part B in .

[0031] In the picture:

[0032] 11. Gravity oil removal tank; 12. DAF flotation device; 13. Heavy medium sedimentation device; 14. Sludge thickening tank;

[0033] 21, pipe 1; 22, pipe 2; 23, pipe 3;

[0034] 3. Snail stacking dehydrator;

[0035] 4. No. 1 oil collector;

[0036] 5. No. 2 floating oil collector; 51. Floating oil suction piece; 52. Oil suction pipe; 53. Rigid pipe; 531. Upper pipe; 532. Middle pipe; 533. Lower pipe; 534. Connecting rod;

[0037] 61. Filter; 62. Rotating arm; 63. Rotating shaft; 64. Bracket; 65. Motor No. 1; 66. Motor No. 2;

[0038] 7. Hair dryer;

[0039] 8. Conical ring mouth;

[0040] 9. Rubber ring;

[0041] 101. Drain pipe; 102. Water purification device. DETAILED DESCRIPTION

[0042] The present invention will be described in further detail below with reference to the accompanying drawings.

[0043] Example, an oily wastewater degreasing system, referring to Figure 1-Figure 5 , including a gravity oil removal tank 11, a DAF flotation device 12 and a heavy medium sedimentation device 13 which are connected in sequence. The three are connected by a pipeline, and water and sludge are transported downward in sequence through the pump body. The pump body and valve on the pipeline between two adjacent devices are used to cut off.

[0044] The gravity deoiling tank 11 is provided with an inlet pipe, which is used for pouring sludge.

[0045] The heavy medium sedimentation device 13 is provided with a drain pipe 101 for discharging sewage. A water purification component 102 is installed on the drain pipe 101. After the sewage flows through the water purification component 102, the water is further purified. The water purification component 102 is a filter with a filter membrane inside.

[0046] Also includes a sludge thickening tank 14;

[0047] The sludge thickening tank 14 is provided with a No. 1 pipe 21 for collecting the sludge discharged from the gravity de-oiling tank 11. The No. 1 pipe 21 is used to transport the sludge from the gravity de-oiling tank 11 to the sludge thickening tank 14. The No. 1 pipe 21 is provided with a pump body and a stop valve for controlling the transportation and stopping of the sludge.

[0048] The sludge thickening tank 14 is provided with a No. 2 pipe 22 for collecting sludge from the DAF flotation device 12. The No. 2 pipe 22 is used to transport the sludge from the DAF flotation device 12 to the sludge thickening tank 14. The No. 2 pipe 22 is provided with a pump body and a stop valve for controlling the transport and stop of sludge.

[0049] The sludge thickening tank 14 is provided with a No. 3 pipe 23 for collecting sludge from the heavy medium settling device 13. The No. 3 pipe 23 is used to transport the sludge from the heavy medium settling device 13 to the sludge thickening tank 14. The No. 3 pipe 23 is provided with a pump body and a stop valve for controlling the transportation and stopping of the settled sludge.

[0050] The sludge thickening tank 14 is connected to the screw press dewatering machine 3. The sludge collected in the sludge thickening tank 14 is transported to the screw press dewatering machine 3 through a pump body and a pipeline. The screw press dewatering machine 3 quickly dehydrates the sludge to obtain a dry mud cake.

[0051] The screw dewatering machine 3 is a highly efficient solid-liquid separation equipment. Driven by the screw, the filter gap and pitch of the screw dewatering machine 3 gradually become smaller, and under the blocking effect of the back pressure plate, a huge internal pressure is generated, and the volume continues to shrink, thereby achieving the purpose of sufficient dehydration; during dehydration, the concentrated sludge continues to move forward with the rotation of the screw shaft; along the direction of the mud cake outlet, the pitch of the screw shaft gradually becomes smaller, the gap between the rings also gradually becomes smaller, and the volume of the spiral cavity continues to shrink; under the action of the back pressure plate at the outlet, the internal pressure gradually increases, and under the continuous operation and push of the spiral driving shaft, the water in the sludge is squeezed out, the solid content of the filter cake continues to increase, and finally the continuous dehydration of the sludge is achieved.

[0052] The main body of the gravity oil removal tank 11 is a tank body with a relatively simple structure. After the original sludge enters the tank body, it relies on the action of gravity to realize the stratification of water, oil and sludge layers after standing. Due to the difference in density, the bottom is sludge, the middle is a mixture of water, and the upper layer is oil with a density lower than that of water.

[0053] The gravity oil removal tank 11 is provided with a No. 1 floating oil collector 4, which is also provided with a floating oil absorber. The oil absorber absorbs the oil in the upper layer and transports it to the oil separator for physical oil-liquid separation.

[0054] The sludge that has been initially settled is transported to the sludge thickening tank 14 through the No. 1 pipe 21 .

[0055] The water mixture in the gravity deoiling tank 11 is transferred to the DAF flotation device 12 , which is designed to remove the suspended solids, grease and insoluble organic matter remaining in the wastewater.

[0056] The DAF flotation unit 12 is a highly efficient and rapid device for separating solid particles from water and wastewater. Its working principle is that a portion of the treated wastewater is circulated into the dissolved air tank. Under the pressurized air, the air becomes supersaturated and dissolved. It is then mixed with raw water containing a dilution agent at the inlet of the flotation tank. As the pressure decreases, the supersaturated air is released, forming tiny bubbles that quickly attach to suspended matter and lift it to the surface of the flotation tank. This creates a sludge layer that is easily removed, while heavier solid matter settles to the bottom of the tank and is also removed.

[0057] The DAF air flotation device 12 is provided with a No. 2 floating oil collector 5 ; the No. 2 floating oil collector 5 is provided with a floating oil suction member 51 , and the floating oil suction member 51 is connected to an oil suction pipe 52 .

[0058] The oil suction pipe 52 includes a vertical hard pipe 53 , both ends of which are soft pipes. One end of the soft pipe is connected to the floating oil suction component 51 , and the other end of the soft pipe is connected to the oil separator.

[0059] A rotary filter assembly is provided at the position of the hard pipe 53 to pour the scum into the second pipe 22 .

[0060] The hard tube 53 includes an upper tube 531, a middle tube 532 and a lower tube 533. The middle tube 532 connects the upper tube 531 and the lower tube 533. The upper tube 531 and the lower tube 533 are both provided with a concave-shaped connecting rod 534. The rotary filter assembly includes a filter screen 61 fixed in the middle tube 532 and a rotating arm 62 connected to the outer wall of the middle tube 532. The filter screen 61 is a stainless steel screen.

[0061] The rotating arm 62 is connected to the rotating shaft 63, the rotating shaft 63 is connected to the bracket 64, and the bracket 64 is connected to the No. 1 motor 65 that drives the rotating shaft 63 to rotate horizontally to bring the middle tube 532 to separate the upper tube 531 and the lower tube 533; secondly, the bracket 64 fixes and supports the lower tube 533.

[0062] The rotating arm 62 is rotationally connected to the middle tube 532, and the rotating arm 62 is provided with a No. 2 motor 66 that drives the middle tube 532 to rotate vertically; the base of the No. 2 motor 66 is fixed in the rotating arm 62, and the motor shaft of the No. 2 motor 66 is fixed to the middle tube 532, so the No. 2 motor 66 can rotate vertically along the middle tube 532.

[0063] The first motor 65 and the second motor 66 are each provided with a respective control switch for controlling their respective on / off, forward and reverse rotation.

[0064] The inlet of the No. 2 pipe 22 is opened vertically upward, and a steel sleeve is fixed to the inlet of the No. 2 pipe 22; and the middle pipe 532 separating the upper pipe 531 and the lower pipe 533 is located directly above the No. 2 pipe 22, and the inlet diameter of the No. 2 pipe 22 is 3 times the diameter of the middle pipe 532.

[0065] A downward blowing blower 7 is provided just above the second tube 22, and the blower 7 is located above the middle tube 532. The blower 7 is turned on and off by a separate switch.

[0066] The outlet end of the upper tube 531 is provided with a conical ring opening 8 , which is located on the inner wall of the upper tube 531 , with the lower end of the conical ring opening 8 facing the middle tube 532 , and the lower edge of the conical ring opening 8 is located inside the upper tube 531 .

[0067] The upper and lower edges of the middle tube 532 are both sealed with rubber rings 9.

[0068] The working principle of the rotary filter assembly is that the hard tube 53 is vertically arranged to transmit the water, oil and scum sucked by the floating oil suction element 51, wherein the scum is filtered in the filter screen 61;

[0069] When the floating oil suction member 51 stops working, the No. 1 motor 65 drives the middle tube 532 to rotate horizontally to just above the No. 2 tube 22, and then the No. 2 motor 66 drives the middle tube 532 to rotate vertically, so that the filter screen 61 is inverted, and the scum in the filter screen 61 enters the No. 2 tube 22. Since the pipe opening of the No. 2 tube 22 is larger than the middle tube 532, the scum in the middle tube 532 will basically not leak.

[0070] Then the blower 7 is started to blow the scum adhered in the middle tube 532 into the second tube 22.

[0071] After the second pipe 22 is cleaned of scum, it can be rotated and reset to the hard pipe 53.

[0072] The wastewater treated by the DAF flotation device 12 is transported to the heavy medium sedimentation device 13 through a pump body; in the heavy medium sedimentation device 13, heavy medium powder and flocculant are added to the reaction tank. The addition of heavy medium powder acts as a ballasting or weighting agent, thereby accelerating the sedimentation process; the settled sludge is transported to the sludge thickening tank 14 through the No. 2 pipe 22.

[0073] The heavy medium sedimentation device 13 is provided with a drainage pipe 101 , and the drainage pipe 101 is connected to a water purification component 102 .

[0074] The various types of sludge in the sludge thickening tank 14 are transported to the screw press dewatering machine 3 for further solid-liquid separation to obtain a relatively dry mud cake.

[0075] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, certain improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An oily wastewater deoiling system comprising a gravity deoiling tank (11), a DAF flotation device (12) and a heavy medium sedimentation device (13) connected in sequence, characterized in that: The sludge concentrating tank (14) is also provided with a No. 1 pipe (21) for collecting slag from the gravity oil removal tank (11), a No. 2 pipe (22) for collecting slag from the DAF flotation device (12), and a No. 3 pipe (23) for collecting sludge from the heavy medium sedimentation device (13). The sludge concentrating tank (14) is connected to a screw press dewatering machine (3). The gravity oil removal tank (11) is provided with a No. 1 floating oil collector (4), and the DAF flotation device (12) is provided with a No. 2 floating oil collector (5); the No. 2 floating oil collector (5) is provided with a floating oil suction piece (51), the floating oil suction piece (51) is connected to an oil suction pipe (52), and the oil suction pipe (52) is provided with a rotary filter assembly for pouring scum into the No. 2 pipe (22).

2. The oily wastewater deoiling system according to claim 1, characterized in that: The oil suction pipe (52) includes a vertical hard pipe (53), the hard pipe (53) includes an upper pipe (531), a middle pipe (532) and a lower pipe (533), the middle pipe (532) is connected to the upper pipe (531) and the lower pipe (533), the upper pipe (531) and the lower pipe (533) are both provided with a concave connecting rod (534), the rotary filter assembly includes a filter screen (61) fixed in the middle pipe (532) and a rotating arm (62) connected to the outer wall of the middle pipe (532), the rotating arm (62) is connected to a rotating shaft (63), the rotating shaft (63) is connected to a bracket (64), and the bracket (64) is connected to a motor (65) that drives the rotating shaft (63) to rotate horizontally to drive the middle pipe (532) to separate the upper pipe (531) and the lower pipe (533).

3. The oily wastewater deoiling system according to claim 2, characterized in that: The rotating arm (62) and the middle tube (532) are rotatably connected, and the rotating arm (62) is provided with a second motor (66) for driving the middle tube (532) to rotate vertically; The inlet of the second pipe (22) is opened vertically upward, and the middle pipe (532) separating the upper pipe (531) and the lower pipe (533) is located directly above the second pipe (22). The inlet diameter of the second pipe (22) is larger than the diameter of the middle pipe (532).

4. The oily wastewater deoiling system according to claim 3, characterized in that: A blower (7) for blowing air downwards is provided just above the No. 2 pipe (22), and the blower (7) is located above the middle pipe (532).

5. The oily wastewater deoiling system according to claim 4, characterized in that: The outlet end of the upper tube (531) is provided with a conical ring opening (8), which is located on the inner wall of the upper tube (531), with the lower opening of the conical ring opening (8) facing the middle tube (532), and the lower edge of the conical ring opening (8) located inside the upper tube (531).

6. The oily wastewater deoiling system according to claim 5, characterized in that: The upper and lower edges of the middle tube (532) are both sealed with rubber rings (9).

7. The oily wastewater deoiling system according to claim 5, characterized in that: The filter screen (61) is a stainless steel screen.

8. The oily wastewater deoiling system according to claim 1, characterized in that: The heavy medium precipitation device (13) is provided with a drainage pipe (101), and the drainage pipe (101) is connected to the water purification component (102).

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