Method and device for reducing pollution discharge during operation of small oil-water tank

Abstract

The present application relates to the field of oil pollution treatment, and discloses a small oil-water tank operation process sewage reduction method and device, which comprises a sewage gate valve, a hole blind plate, a high-pressure water gun, a water gun propulsion mechanism and a water gun sealing mechanism; the sewage gate valve is a flange type knife gate valve; the hole blind plate is fixed on the outer flange of the sewage gate valve; the high-pressure water gun comprises a water gun pipe; the water gun propulsion mechanism comprises a base, a support, a guide rod and a ball screw; the water gun sealing mechanism comprises a sealing pipe base, a sealing gasket and a sealing gland; the present application realizes oil pollution cleaning and reduction integration under the condition of not lowering the liquid level of the oil-water tank, not affecting the production operation and ensuring safety, timely cleaning the oil-containing sludge out of the tank, and achieving the separation of oil-water and sludge, which is the best solution for small oil-water tank sludge cleaning under low-cost conditions; the separated oil-water returns to the tank through the liquid gun, realizing recycling.

Description

Technical Field

[0001] This invention relates to the field of oil pollution treatment, and specifically to a method and apparatus for reducing the amount of wastewater discharged during the operation of a small oil-water tank. Background Technology

[0002] After a period of operation, the oil and water tanks in oilfield production plants gradually settle at the bottom, forming layers of oil sand, oil sludge, water, and oil, eventually filling a space with flammable oil and gas. As the sludge layer rises to a certain height (generally 1-2 meters), it affects the operation of the oil and water tanks and impacts the quality of the oil and water. Because the drain outlet is located at the bottom of the tank, once buried by sediment, it cannot be discharged by opening the valve, necessitating periodic shutdowns for tank cleaning.

[0003] The technology for cleaning sludge deposited in oil-water tanks has gone through the following stages:

[0004] The first stage involved opening the manhole of the oil and water tank and manually entering to clean up the deposited oil and cement mixture. Later, with the improvement of safety and environmental protection standards, this method was gradually prohibited.

[0005] The second stage: While manually cleaning the tanks, various units and technical personnel at all levels conducted a large number of tests on various types of pre-installed sludge and sand removal devices inside the tanks, but none of them achieved good results and were promoted. This technical approach was basically rejected.

[0006] The third stage: Tank cleaning and sludge removal method. The liquid level inside the tank is lowered to the minimum. Then, the system is connected to the sludge drain and the upper liquid inlet (or manhole) inside the tank. Water is continuously sprayed downwards into the tank using a water gun to agitate the oily sludge deposited at the bottom. The oily sludge mixture is then discharged from the tank using a pump connected to the sludge drain. Simultaneously, a large amount of nitrogen is injected into the tank to reduce the oxygen content and decrease the risk of explosion. This technology is now widely used and has become the mainstream technology in the industry, especially in cleaning oil-water tanks with capacities exceeding 10,000 cubic meters, where it operates stably and reliably.

[0007] However, despite numerous safety measures, explosions during tank cleaning in oil-water tanks with a capacity of less than 5,000 cubic meters have been frequent in recent years. The reasons for this are twofold: technically, the main cause is the presence of flammable and explosive gases inside the tank, which, when exposed to static electricity generated by various factors (water flow impact, pipeline friction, various operations, etc.), can lead to combustion and explosion accidents, causing injury to personnel and equipment. Economically, cleaning tanks with a capacity of over 10,000 cubic meters is expensive, requires high-standard personnel and equipment, and necessitates thorough measures; however, for tanks under 5,000 cubic meters, or even smaller tanks of a few hundred cubic meters, employing high-standard personnel and equipment is prohibitively costly for the operating companies. Currently, many explosions during tank cleaning are caused by inexplicable static electricity. Therefore, oilfields urgently need to solve the following technical problem: promptly removing oily sludge from oil-water tanks with a capacity of less than 5,000 cubic meters and achieving separation of oil, water, and sludge. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a method and apparatus for reducing sewage discharge during the operation of a small oil-water tank, the technical solution of which is as follows:

[0009] A method for reducing wastewater discharge during the operation of a small oil-water tank, wherein the capacity of the small oil-water tank is less than 5000 cubic meters, and the interior of the oil-water tank consists of, from top to bottom, an oil and gas space layer, an oil layer, a water layer, and an oil sludge sedimentation layer; the method includes the following steps:

[0010] (1) When the oil sludge sedimentation layer at the bottom of the oil-water tank reaches 1 to 1.5 meters, the sewage should be discharged to reduce the amount of sewage while the oil-water tank is running normally and there is no need to lower the liquid level;

[0011] (2) Connect the drain outlet at the bottom of the oil-water tank to a wastewater reduction device including a drain valve and a high-pressure flushing gun;

[0012] (3) Under the premise of ensuring that the liquid in the oil-water tank does not leak, insert the high-pressure water gun into the oil-water tank to impact the oil sludge sediment layer; control the water flow below the liquid level in the oil-water tank so as not to disturb the liquid layer above the oil sludge sediment layer.

[0013] (4) After the oily sludge is discharged through the drain valve, it is transferred to the centrifuge for solid-liquid separation by the drain pump; the separated oily sludge is bagged and transported out according to the procedure; part of the separated oil-water mixture is fed into the tank through the oil-water tank inlet system, and the other part is introduced into the flushing gun for reuse through the high pressure pump.

[0014] A device for reducing wastewater discharge during the operation of a small oil-water tank is disclosed. This device is adapted to the aforementioned method for reducing wastewater discharge during the operation of a small oil-water tank. It includes a wastewater gate valve, a perforated blind flange, a high-pressure water jet gun, a water jet propulsion mechanism, and a water jet sealing mechanism. The wastewater gate valve is installed at the bottom of the oil-water tank's wastewater outlet and is a flange-type knife gate valve. The perforated blind flange is fixed to the outer flange of the wastewater gate valve and has a wastewater discharge hole and a sealing hole. The high-pressure water jet gun includes a water jet pipe. The water jet propulsion mechanism includes a base, a bracket, a guide rod, and a ball screw. The base is fixed to the perforated blind flange and has a guide rod mounting hole, a bearing mounting hole, and a first clamp-type movable fixing component on one side. The ball screw includes a screw thread. The bracket includes a guide rod through hole, a nut mounting hole, and a second clamp-type movable fixing component on one side. One end of the guide rod is connected to the guide rod mounting hole, and the rod body passes through the guide rod through hole. The front end of the ball screw is connected to the bearing in the bearing mounting hole to achieve unobstructed rotation of the ball screw on the base. The water gun pipe passes through the center of the first clamp-type movable fixing component and the center of the second clamp-type movable fixing component. The water gun sealing mechanism includes a sealing tube seat, a sealing gasket, and a sealing gland. The sealing tube seat is fixed in the sealing hole, and the second clamp-type movable fixing component is fastened around the sealing tube seat. One end of the sealing tube seat has a sealing gasket mounting groove and an internal threaded opening from the inside to the outside. One end of the sealing gland is provided with an external threaded opening that engages with the internal threaded opening.

[0015] Furthermore, the first clamp-type movable fixing component includes a base edge portion with a semi-circular groove in the middle of one side of the base and a base pressure block with the same semi-circular groove in the middle, which is clamp-type movable fixing thereto. The base edge portion and the base pressure block are fixedly connected by bolts. The second clamp-type movable fixing component includes a bracket edge portion with a semi-circular groove in the middle of one side of the bracket and a bracket pressure block with the same semi-circular groove in the middle, which is clamp-type movable fixing thereto. The bracket edge portion and the bracket pressure block are fixedly connected by bolts.

[0016] Furthermore, both the internal and external thread openings are flared.

[0017] Furthermore, the sealing glands are configured as two or more connected in series.

[0018] Furthermore, the other end of the sealing cap is provided with a sealing gasket mounting groove and an internal thread opening from the inside out.

[0019] Furthermore, the bearing is a deep groove ball bearing with dust covers on both sides.

[0020] Furthermore, the flanged knife gate valve is a manually operated flanged knife gate valve.

[0021] Furthermore, the sealing gasket installed in the sealing gasket mounting groove is made of silicone rubber.

[0022] Furthermore, the drain hole is equipped with a drain pipe with a control valve.

[0023] This invention is based on the following fundamental theoretical foundations:

[0024] This invention, based on the three elements of combustion and explosion, and considering the characteristics of oil-water tank operation and sewage discharge, proposes a system for periodically removing oily sludge from the bottom of the oil-water tank without stopping operation. The sludge is then dehydrated, and the dehydrated sludge is transported off-site according to regulations. The oil and water are returned to the tank, thus achieving uninterrupted production and reduced oily sludge volume while ensuring safety. The three elements of explosion are combustible material, oxygen, and an ignition source. The contents of the oil-water tank are liquids such as oil and water. As long as the tank is full of liquids, even direct contact with an ignition source will not lead to combustion or explosion. Therefore, during operation, as long as the tank is full of oil or water (liquid) or the work surface is below the liquid level, there will be absolutely no chance of combustion or explosion caused by random static sparks.

[0025] In addition, the oil and cement that need to be discharged from the oil-water tank are deposited at the bottom of the tank. The oil-cement-sand mixture layer and the water and oil layers are clearly separated. There should be a drain valve at the bottom that can be connected to external equipment.

[0026] Compared with the prior art, the present invention has the following main advantages:

[0027] 1. This invention achieves integrated oil and water pollution removal without lowering the liquid level in the oil-water tank, without affecting production operations, and while ensuring safety. It promptly removes oily sludge from the tank and separates oil, water, and sludge, making it the best solution for sludge cleaning of small oil-water tanks under low-cost conditions.

[0028] 2. The oil and water separated by this invention are returned to the tank through a spray gun, achieving recycling.

[0029] 3. The method of the present invention is simple, the device is reliable, and it has good prospects for promotion. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0031] Figure 2 This is one of the three-dimensional structural diagrams of the sewage reduction device of the present invention (the base is not yet fixed to the perforated blind plate).

[0032] Figure 3 This is the second three-dimensional structural diagram of the sewage reduction device of the present invention (the base has been fixed on the perforated blind plate).

[0033] Figure 4 for Figure 3 A frontal view diagram;

[0034] Figure 5 This is a cross-sectional schematic diagram of the water gun sealing mechanism of the sewage reduction device of the present invention;

[0035] Figure 6 This is a three-dimensional schematic diagram of the water gun propulsion mechanism of the sewage reduction device of the present invention;

[0036] In the diagram: 1-Sewage gate valve, 2-Base, 3-Sewage hole, 4-Guide rod mounting hole, 5-Bearing mounting hole, 6-Guide rod through hole, 7-Guide rod, 8-Nut mounting hole, 9-Ball screw, 10-Bracket, 11-Second clamp-type movable fixing part, 11.1-Bracket edge, 11.2-Bracket pressure block, 12-Sealing cover, 13-First clamp-type movable fixing part, 13.1-Base edge, 13.2-Base pressure block, 14-Sealing hole, 15-Sewage pipe, 16-Blind flange with perforation, 17-Flange, 18-Water gun pipe, 19-Sewage outlet, 20-Sealing pipe seat, 21-Sealing gasket mounting groove, 22-Sealing gasket, 23-Internal thread, 24-External thread, 25-Bearing. Detailed Implementation

[0037] The invention will now be described in detail with reference to specific embodiments and accompanying drawings. Example 1

[0038] See Figures 1 to 6A device for reducing wastewater discharge during the operation of a small oil-water tank includes a wastewater gate valve 1, a perforated blind flange 16, a high-pressure water jet gun, a water jet propulsion mechanism, and a water jet sealing mechanism. The wastewater gate valve 1 is installed at the wastewater outlet 19 at the bottom of the oil-water tank, and the wastewater gate valve is a flange-type knife gate valve. The perforated blind flange 16 is fixed to the outer flange 17 of the wastewater gate valve 1, and the perforated blind flange 16 has a wastewater outlet 3 and a sealing outlet 14. The high-pressure water jet gun includes a water jet pipe 18. The water jet propulsion mechanism includes a base 2, a bracket 10, a guide rod 7, and a ball screw 9. The base 2 is fixed to the perforated blind flange 16, and the base 2 has a guide rod mounting hole 4, a bearing mounting hole 5, and a first clamp-type movable fixing part 13 on one side. The ball screw 9 includes a screw, a nut, and balls. The bracket 10 has a guide rod through hole 6 and a nut mounting hole 6. The mounting hole 8 is provided on one side with a second clamp-type movable fixing part 11. One end of the guide rod 7 is connected to the guide rod mounting hole 4, and the rod body passes through the guide rod through hole 6. The front end of the ball screw 9 is connected to the bearing 25 in the bearing mounting hole 5 to realize the ball screw 9 rotating on the base 2 without resistance. The water gun pipe 18 passes through the center of the first clamp-type movable fixing part 13 and the center of the second clamp-type movable fixing part 11. The water gun sealing mechanism includes a sealing tube seat 20, a sealing gasket 22 and a sealing cap 12. The sealing tube seat 20 is fixed in the sealing hole 14. The second clamp-type movable fixing part 11 is fastened around the sealing tube seat 20. One end of the sealing tube seat 20 is provided with a sealing gasket mounting groove 21 and an internal threaded port 23 from the inside to the outside. One end of the sealing cap 12 is provided with an external threaded port 24 that meshes with the internal threaded port 23. Example 2

[0039] See Figures 1 to 6 A small oil-water tank wastewater reduction device, based on the technical solution described in Embodiment 1, includes a first clamp-type movable fixing component 13 comprising a base edge portion 13.1 with a semi-circular groove in the middle of one side of the base 2 and a base pressure block 13.2 with the same semi-circular groove in the middle, which is clamped and movable therewith. The base edge portion 13.1 and the base pressure block 13.2 are fixedly connected by bolts. A second clamp-type movable fixing component 11 comprises a bracket edge portion 11.1 with a semi-circular groove in the middle of one side of the bracket 10 and a bracket pressure block 11.2 with the same semi-circular groove in the middle, which is clamped and movable therewith. The bracket edge portion 11.1 and the bracket pressure block 11.2 are fixedly connected by bolts. The first clamp-type movable fixing component 13 achieves a stable clamping of the sealing pipe seat 20 through its unique structure, and the second clamp-type movable fixing component 11 achieves a stable gripping of the water gun pipe 18 through its unique structure. The clamp-type movable fixing also facilitates disassembly and assembly. Example 3

[0040] See Figures 1 to 6A device for reducing sewage discharge during the operation of a small oil-water tank, based on the technical solution described in Example 1, wherein both the internal thread port 23 and the external thread port 24 are flared to enhance the firmness of the thread engagement. Example 4

[0041] See Figures 1 to 6 A device for reducing sewage discharge during the operation of a small oil-water tank, based on the technical solution described in Embodiment 1, wherein the sealing cap 12 is configured as two or more connected in series; the other end of the sealing cap 12 is provided with a sealing gasket mounting groove 21 and an internal threaded opening 23 from the inside to the outside, so as to facilitate series installation. Example 5

[0042] See Figures 1 to 6 A device for reducing sewage discharge during the operation of a small oil-water tank, based on the technical solution described in Example 1, wherein the bearing 25 is a deep groove ball bearing with dust covers on both sides to prevent dust from entering the bearing raceway. Example 6

[0043] See Figures 1 to 6 A device for reducing sewage discharge during the operation of a small oil-water tank, based on the technical solution described in Example 1, uses a manual flanged knife gate valve, which is simple and practical. Example 7

[0044] See Figures 1 to 6 A device for reducing sewage discharge during the operation of a small oil-water tank, based on the technical solution described in Example 1, wherein the sealing gasket 22 installed in the sealing gasket mounting groove 21 is made of silicone rubber, which is resistant to both low and high temperatures and has good oil resistance. Example 8

[0045] See Figures 1 to 6 A device for reducing sewage discharge during the operation of a small oil-water tank, based on the technical solution described in Embodiment 1, includes a sewage discharge pipe 15 equipped with a control valve on the sewage discharge port 3 for better connection to sewage discharge equipment.

[0046] To enable those skilled in the art to better understand the present invention, its basic process method is briefly described below:

[0047] A method for reducing wastewater discharge during the operation of a small oil-water tank, wherein the tank has a capacity of less than 5000 cubic meters, and the interior of the tank consists of, from top to bottom, an oil and gas space layer, an oil layer, a water layer, and an oil sludge sedimentation layer; the method includes the following steps:

[0048] (1) When the oil sludge sedimentation layer at the bottom of the oil-water tank reaches 1 to 1.5 meters, the sewage should be discharged to reduce the amount of sewage while the oil-water tank is running normally and there is no need to lower the liquid level;

[0049] (2) Connect the drain outlet 19 at the bottom of the oil-water tank to the drain reduction device, which includes the drain gate valve 1 and the high-pressure flushing gun.

[0050] (3) Under the premise of ensuring that the liquid in the oil-water tank does not leak, insert the high-pressure water gun into the oil-water tank to impact the oil sludge deposit layer; control the impact water flow below the liquid surface in the oil-water tank so as not to disturb the liquid layer above the oil sludge deposit layer.

[0051] (4) After the oily sludge is discharged through the sewage gate valve 1, it is transferred to the centrifuge for solid-liquid separation by the sewage pump; the separated oily sludge is bagged and transported out according to the procedure; part of the separated oil-water mixture is fed into the tank through the oil-water tank inlet system, and the other part is introduced into the flushing gun for reuse through the high pressure pump.

[0052] Specific operational details are as follows:

[0053] Insert the water gun pipe 18 into the center of the sealing gasket 22 until it is close to the valve plate of the drain valve 1. Align the thread of the sealing cap 12 with the sealing gasket mounting groove 21 and tighten it, so that the sealing gasket 22 is compressed and deformed in the sealing gasket mounting groove 21, tightly adhering to the water gun pipe 18 to achieve a sealing effect. Place the sealing gasket 22 into the sealing gasket mounting groove 21 on the back of the sealing cap 12, and then install another sealing cap 12. Repeat the tightening action to deform the sealing gasket 22 in the sealing gasket mounting groove 21 and seal it with the water gun pipe 18. The sealing cap 12 can be repeatedly installed up to three or more times.

[0054] Open the valve plate of the drain gate valve 1, adjust the tightness of the sealing cover 12, and rotate the ball screw 9 to move the bracket 10 towards the drain gate valve 1 under the guidance of the guide rod 7, thereby driving the water gun pipe 18 to extend into the tank; when the ball screw 9 cannot rotate, the tightness of the sealing cover 12 can be appropriately loosened.

[0055] When the bracket 10 approaches the drain valve 1, loosen the bracket pressure block 11.2, rotate the ball screw 9 in the opposite direction to the furthest point from the drain valve 1, and then fix the bracket pressure block 11.2. Repeat the above operation. As the water flow impacts, continuously insert the water gun pipe 18 into the tank to disturb the sediment at the bottom of the tank, so that the sediment is discharged out of the tank along the drain pipe 15. Thus, the sediment in the tank is discharged without stopping production or emptying the liquid in the tank, thereby achieving the tank cleaning operation without stopping production or emptying the liquid in the tank.

Claims

1. A device for reducing wastewater discharge during the operation of a small oil-water tank, characterized in that, The device includes a drain gate valve, a perforated blind flange, a high-pressure water jet gun, a water jet propulsion mechanism, and a water jet sealing mechanism. The drain gate valve is installed at the drain port at the bottom of the oil-water tank and is a flange-type knife gate valve. The perforated blind flange is fixed to the outer flange of the drain gate valve and has a drain hole and a sealing hole. The high-pressure water jet gun includes a water jet pipe. The water jet propulsion mechanism includes a base, a bracket, a guide rod, and a ball screw. The base is fixed to the perforated blind flange and has a guide rod mounting hole, a bearing mounting hole, and a first clamp-type movable fixing component on one side. The ball screw includes a screw, a nut, and balls. The bracket has a guide rod through hole and a nut mounting hole. The hole is provided with a second clamp-type movable fixing component on one side. One end of the guide rod is connected to the guide rod mounting hole, and the rod body passes through the guide rod through hole. The front end of the ball screw is connected to the bearing in the bearing mounting hole to realize the ball screw rotating on the base without resistance. The water gun pipe passes through the center of the first clamp-type movable fixing component and the center of the second clamp-type movable fixing component. The water gun sealing mechanism includes a sealing tube seat, a sealing gasket, and a sealing gland. The sealing tube seat is fixed in the sealing hole, and the second clamp-type movable fixing component is fastened around the sealing tube seat. One end of the sealing tube seat is provided with a sealing gasket mounting groove and an internal threaded opening from the inside to the outside. One end of the sealing gland is provided with an external threaded opening that meshes with the internal threaded opening. The first clamp-type movable fastener includes a base edge portion with a semi-circular groove in the middle of one side of the base and a base pressure block with the same semi-circular groove in the middle, which is clamp-type movablely fixed to the base. The base edge portion and the base pressure block are fixedly connected by bolts. The second clamp-type movable fastener includes a bracket edge portion with a semi-circular groove in the middle of one side of the bracket and a bracket pressure block with the same semi-circular groove in the middle, which is clamp-type movable to the bracket. The bracket edge portion and the bracket pressure block are fixedly connected by bolts.

2. The device for reducing wastewater discharge during the operation of a small oil-water tank according to claim 1, characterized in that, Both the internal and external thread openings are flared.

3. The device for reducing wastewater discharge during the operation of a small oil-water tank according to claim 1, characterized in that, The sealing glands are configured as two or more connected in series.

4. The device for reducing wastewater discharge during the operation of a small oil-water tank according to claim 1, characterized in that, The other end of the sealing gland is provided with a sealing gasket mounting groove and an internal thread opening from the inside out.

5. The device for reducing wastewater discharge during the operation of a small oil-water tank according to claim 1, characterized in that, The bearing is a deep groove ball bearing with dust covers on both sides.

6. The device for reducing wastewater discharge during the operation of a small oil-water tank according to claim 1, characterized in that, The flanged knife gate valve is a manually operated flanged knife gate valve.

7. The device for reducing wastewater discharge during the operation of a small oil-water tank according to claim 1, characterized in that, The sealing gasket installed in the sealing gasket mounting groove is made of silicone rubber.

8. The device for reducing wastewater discharge during the operation of a small oil-water tank according to claim 1, characterized in that, The drain hole is equipped with a drain pipe with a control valve.

9. A method for reducing wastewater discharge during the operation of a small oil-water tank, the method relying on a wastewater reduction device for the operation of a small oil-water tank as described in any one of claims 1-8, wherein the capacity of the small oil-water tank is less than 5000 cubic meters, and the interior of the oil-water tank consists of, from top to bottom, an oil and gas space layer, an oil layer, a water layer, and an oil sludge sedimentation layer, characterized in that... The method includes the following steps: (1) When the oil sludge sedimentation layer at the bottom of the oil-water tank reaches 1 to 1.5 meters, the sewage should be discharged to reduce the amount of sewage while the oil-water tank is running normally and there is no need to lower the liquid level; (2) Connect the drain outlet at the bottom of the oil-water tank to a wastewater reduction device including a drain valve and a high-pressure flushing gun; (3) Under the premise of ensuring that the liquid in the oil-water tank does not leak, insert the high-pressure water gun into the oil-water tank to impact the oil sludge sediment layer; control the water flow below the liquid level in the oil-water tank so as not to disturb the liquid layer above the oil sludge sediment layer. (4) After the oily sludge is discharged through the drain valve, it is transferred to the centrifuge for solid-liquid separation by the drain pump; the separated oily sludge is bagged and transported out according to the procedure; part of the separated oil-water mixture is fed into the tank through the oil-water tank inlet system, and the other part is introduced into the flushing gun for reuse through the high pressure pump.

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