RU2805225C2 - Coalescing filter for wastewater treatment with preliminary filtration of mechanical impurities and suspended substances - Google Patents

Abstract

FIELD: wastewater treatment.

SUBSTANCE: invention relates to devices for wastewater treatment and is applicable at oil enterprises. The coalescence filter includes a housing and elements with holes of various diameters, an inspection tube, heating elements, a demulsifier supply pipeline, waste water supply, oil removal and clean water pipelines. The coalescent filter is additionally equipped with a filter for purifying mechanical impurities and suspended substances, an additional section of pipeline connected to the oil delivery pipeline, as well as two optical sensors with the ability to determine oil and water levels.

EFFECT: increasing the efficiency of wastewater treatment from oil and oil products due to the preliminary treatment of wastewater from mechanical impurities and suspended substances and the accuracy of determining oil and water levels.

3 cl, 1 dwg

Description

The present invention relates to devices for wastewater treatment at gas stations (gas stations), oil depots and oil gathering points at oil producing enterprises.

To clean stormwater from the territory of gas stations and oil collection points, they must include underground treatment facilities that ensure the treatment of wastewater to the requirements of the maximum permissible concentration standards for wastewater on the ground, into urban storm sewers or into fishery reservoirs. For these purposes, treatment facilities of both domestic and imported origin can be used that meet the specified requirements [Bondar V.A., Zorya E.I., Tsagareli D.V. Operations with petroleum products. M.: JSC "Paritet", 1999 - 338 pp.]. The main indicator of the operation of treatment facilities is the quality of treatment. Before being discharged from the territory of gas stations, oil depots into city storm sewers or into a reservoir, industrial and waste water must be treated in accordance with existing regulatory requirements to a concentration of petroleum products of 0.05 mg/l. The concentration of suspended solids should not exceed 10.5 mg/l. [Kovalenko V.G., Zorya E.I., Frolov Yu.N. Environmental safety in petroleum product supply systems and road transport. Tutorial. M. LLC "Center LitNefteGaz", 2004 - 176 p.].

At gas stations, oil depots and oil collection points, wastewater is contaminated with gasoline, diesel fuel, oil, motor and transmission oils. All of the listed petroleum products and oil are classified as fuels and lubricants. Petroleum products and oil form water-fuel emulsions with water. The most durable emulsions are formed by fuels and lubricants with a density close to the density of water (oil, oils).

A known installation for treating wastewater from oil and petroleum products using a coalescent filter [Matveev Yu.A. and others. Utility model patent No. 158366 dated December 27, 2015]. The wastewater receiving grid, which has a receiving pipeline with a valve, is equipped with two settling filters. The settling filters are connected via a process pipeline to a vertical tank for collecting wastewater. The wastewater treatment plant includes electric pumping units. The electric pumping unit is designed to pump fuel with a top layer of water into a separate tank for collecting petroleum products (oil). The same electric pumping unit is designed to pump contaminated wastewater through a process pipeline into a coarse filter, a membrane-type fine filter and into a clean water tank. An electric pumping unit is used to supply clean water through an intake pipe through a clean water pipeline into the city storm drain. The electric pumping unit also serves for self-cleaning of fine and coarse filters. After self-cleaning of the filters, the sludge with water flows through the pipeline into the sludge tank. A separate tank is connected via a process pipeline to a wastewater collection tank. An inspection device is mounted on the process pipeline below the tank to separate oil products from water, which includes a housing, sight glass and flange connections. The wastewater collection tank is equipped with a coalescent filter. The coalescent filter consists of elements. The elements have holes of various diameters. The intake pipe is equipped with flexible hoses that are connected to the suction head. The suction head is mounted on a float and lowered to a depth of 2 to 5 mm. An electric pumping unit is designed for pumping out a vertical tank filled with petroleum product or oil.

The utility model works as follows. Through the wastewater receiving grid, contaminated wastewater with mechanical impurities, suspended solids and oil products enters the first settling filter. In the settling tank, part of the mechanical impurities is deposited at the bottom of the settling filter due to gravitational forces. After passing through the settling tank, the water enters the wastewater collection tank, which is equipped with a coalescence filter. Water passes under the lower filter element. Due to the lower specific gravity of oil and petroleum products compared to the specific gravity of water, they rise upward and come into contact with the surface of the element, while drops of oil and petroleum products slide along the surface of the element and accumulate. Then, through the hole in the elements, drops of petroleum products (oil) flow into the gap between the lower, middle and upper element. There, the process of enlargement of droplets of petroleum products occurs with further flow of droplets through the holes. After this, drops of oil products rise into the upper layer of liquid. After this, using an electrical installation, through an intake pipe with flexible hoses through the slits of the suction heads, the petroleum product (oil) with the top layer of water enters a separate tank.

After pumping out fuels and lubricants, an electric pump unit is used to supply contaminated wastewater through a pipe and process pipeline into a coarse filter, then into a membrane-type fine filter and into a clean water tank. Clean water from the reservoir is pumped out by a second electric pumping unit into the city storm drain or onto the ground. From the tank, the settled water flows through a pipeline into a viewing device for separating oil products from water. The operator monitors the movement of water through a sight glass. When fuels and lubricants appear in the sight glass, it closes the corresponding valve.

The disadvantages of a plant for treating wastewater from oil and petroleum products using coalescence are:

1. Insufficient efficiency of cleaning water-fuel emulsions with a coalescent filter.

2. Low productivity of the installation due to the use of membrane-type filters.

3. Complexity and high cost of installation.

A coalescent filter is also known for purifying wastewater from petroleum products, mechanical impurities and suspended solids [Bogdanov A.Yu., Matveev Yu.A. Utility model patent No. 172536 dated July 11, 2017]. The coalescent filter, which has a waste water receiving pipeline with a valve, pipelines for dispensing clean water and petroleum products, is equipped with two grids with cells of different diameters. In this case, there are cells of a larger diameter on the lower grid, and smaller ones on the upper one. The coalescent filter is also equipped with internal elements. The elements have holes of various diameters. An inspection tube is installed at the top of the coalescent filter to separate oil products from water. Also, the lower part of the filter is equipped with a hatch for cleaning from mechanical impurities and suspended substances.

The utility model works as follows. Through the receiving pipeline, with an open valve, contaminated wastewater with mechanical impurities, suspended solids and oil products enters the coalescence filter. In the filter, part of the mechanical impurities is deposited at the bottom due to gravitational forces. Mechanical impurities of larger diameter are retained by the lower grid, and those of smaller diameter are retained by the upper grid. The gratings also trap suspended substances. Next, the water with oil products passes under the lower element of the coalescence filter. Due to the lower specific gravity of petroleum products compared to the specific gravity of water, they rise upward and come into contact with the surface of the element, while drops of petroleum products slide along the surface of the element and accumulate. Thus, their coalescence occurs. Then, through a hole in the lower element, drops of oil products flow into the gap between the lower and middle elements. There, a similar process of enlargement of oil product droplets occurs near the surface of the intermediate element with further flow of droplets through the holes into the gap between the middle and upper element. After this, drops of petroleum products rise in a similar way through the hole in the upper element into the upper layer of liquid. After filling the filter, the valve of the inlet pipeline is closed. Using the sight tube, the operator sets the oil and water levels. Then, using an inspection tube, he drains the oil product through the outlet pipeline into a separate container. After this, the operator begins to drain clean water through the dispensing pipeline.

The disadvantages of a coalescent filter for treating wastewater from oil products, mechanical impurities and suspended solids are:

1. Insufficient efficiency of cleaning water-fuel emulsions with a coalescent filter.

2. Low rate of separation of water from oil and petroleum products.

3. Collection of mechanical impurities and suspended substances directly in the coalescent filter.

The closest to this problem is a coalescent filter for wastewater treatment at oil producing enterprises [Bogdanov A.Yu., Matveev Yu.A. Utility model patent No. 180681 dated June 21, 2018].

At oil producing enterprises, oil, when mixed with water, forms a stable water-fuel emulsion, to break which it is necessary to use demulsifiers (special reagents for separating water from oil). The heating process also increases the rate of separation of water from oil.

The coalescence filter, which has a waste water receiving pipeline with a valve, pipelines for dispensing clean water and oil (petroleum products), is equipped with two gratings with cells of different diameters. The screens are designed to purify wastewater from mechanical impurities and suspended solids.

The coalescent filter is also equipped with internal elements. The elements have holes of various diameters. The elements are thin corrugated plates made of polyvinyl chloride, which have the properties of attracting particles of petroleum products and drawing away water. When water flows through them, the plates vibrate. This creates conditions for the ascent of enlarged oil particles and the settling of adhering substances from the plates.

An inspection tube is installed at the top of the coalescent filter to separate oil from water.

The lower part of the filter is equipped with a hatch for cleaning from mechanical impurities and suspended substances.

The filter is also equipped with heating elements and a demulsifier supply pipeline with a valve.

The introduction of a demulsifier into a water-oil (water-fuel) emulsion allows one to increase the rate of separation of water from oil and oil products and improve the quality of the separation process.

The utility model works as follows. Through a receiving pipeline with an open valve, contaminated wastewater with mechanical impurities, suspended solids and oil enters the coalescent filter. After the wastewater enters, the heating elements are turned on. When the demulsifier is supplied, the pipeline valve opens. In the filter, part of the mechanical impurities is deposited at the bottom due to gravitational forces. Mechanical impurities of larger diameter are retained by the lower grid, and those of smaller diameter are retained by the upper grid. The gratings also trap suspended substances.

Next, water with oil (petroleum products) passes under the lower element of the coalescent filter. Due to the lower specific gravity of oil compared to the specific gravity of water, oil rises up and comes into contact with the surface of the element, while oil droplets slide along the surface of the element and accumulate. Thus, their coalescence occurs. Then, through a hole in the lower element, drops of oil flow into the gap between the lower and middle element. There, a similar process of enlargement of oil droplets occurs near the surface of the intermediate element with further flow of droplets through the holes into the gap between the middle and upper element. After this, oil drops similarly rise through the hole in the upper element into the upper layer of liquid.

After filling the filter, the valve of the inlet pipeline is closed. Using the sight tube, the operator sets the oil and water levels. Then, using an observation tube, he drains the oil (petroleum product) through the outlet pipeline into a separate container. After this, the operator begins to drain clean water through the dispensing pipeline. When the lower part of the filter is filled with mechanical impurities and suspended substances, the operator opens the hatch and cleans the filter from sediment.

The disadvantages of a coalescent filter for wastewater treatment at oil producing enterprises are:

1. Collection of mechanical impurities and suspended substances directly in the coalescent filter.

2. A large amount of water, which is poured together with oil (petroleum products) into a separate container.

3. Lack of automatic devices for determining oil and water in the coalescent filter.

The proposed invention allows us to solve the problem of increasing the efficiency of wastewater treatment from oil and petroleum products.

The solution to this problem is achieved by the fact that the coalescent filter is additionally equipped with a filter for purifying mechanical impurities and suspended substances, a section of the pipeline for oil delivery, as well as two optical sensors with the ability to determine oil and water levels, with the optical sensors located at a distance of 10-15 cm from each other and connected to the receiving device at the operator’s workplace or other special room.

These features are essential for solving the problem of the invention, since the accuracy increases and the time for determining the levels of oil and water decreases, the amount of water drained along with oil into a separate container is significantly reduced, and the need to clean the coalescent filter from mechanical impurities and suspended substances is eliminated.

Coalescence is the process of enlargement (merging) of droplets of the dispersed phase of an emulsion with the complete loss of the separating interphase surface. The coalescent filter is a housing with elements in the upper part, which have holes of different diameters. The elements are made in the form of the upper part of an ellipsoid.

The essence of the invention is illustrated in Fig. 1, which shows a cross-section of the proposed coalescent filter.

The coalescent filter 1, which has a waste water receiving pipeline 2, with a valve 3, pipelines for dispensing clean water 4 and oil (petroleum products) 5, is equipped with internal elements 6. The elements have holes 7 of different diameters. In this case, the smallest hole diameter is on the bottom element, and the largest on the top. The elements are thin corrugated plates made of polyvinyl chloride, which have the properties of attracting particles of petroleum products and drawing away water. Corrugated plates are self-cleaning. When water flows through them, the plates vibrate. This creates conditions for the ascent of enlarged oil particles and the settling of adhering substances from the plates.

An inspection tube 8 is mounted in the upper part of the coalescence filter to separate oil from water.

The filter is also equipped with heating elements 9 and a demulsifier supply pipeline 10 with a valve 3. The heating elements are designed to heat waste water 11. Heating waste water increases the rate of separation of water from oil 12 (petroleum products).

The introduction of a demulsifier into a water-oil (water-fuel) emulsion allows one to increase the rate of separation of water from oil and oil products and improve the quality of the separation process. The demulsifier is supplied through a pipeline using a dosing pump from a separate container.

Additionally, the receiving pipeline 2 of the coalescent filter 1 is equipped with a filter 13 for cleaning mechanical impurities and suspended substances. Filter 13 is equipped with two gratings 14.15 with cells of different diameters. In this case, the first grid contains cells of a larger diameter, and the second grid has cells of a smaller diameter. At the bottom of the filter 13 there is a tap 16 for draining (cleaning) from mechanical impurities and suspended substances.

The coalescence filter 1 is equipped with a section of pipeline 17 with a valve 3, which is connected to the oil delivery pipeline 5. The section of the pipeline is designed to drain oil at the appropriate level in the filter 1.

Also, the coalescent filter 1 in the upper side part is additionally equipped with two optical sensors 18. The optical sensors are located 10-15 cm from each other. Optical sensors are designed to determine the appropriate levels of oil (petroleum product) and water. The refractive indices of oil and water have different values. Optical sensors 18 are connected to a receiving device at the operator's workplace or other special room.

The invention works as follows. Through the receiving pipeline 2, with an open valve 3, contaminated wastewater 11 with mechanical impurities, suspended solids and oil 12 enters filter 13. In filter 13, part of the mechanical impurities 19 is deposited at the bottom due to gravitational forces. Mechanical impurities of larger diameter are retained by grate 14, and of smaller diameter by grate 15. Also, suspended substances 20 are retained by grates.

Then the wastewater enters the coalescent filter 1. After the wastewater enters, the heating elements 9 are turned on. Depending on the oil contamination of the wastewater, the operator decides to supply (or not supply) the demulsifier through pipeline 10 using a metering pump from a separate container. When the demulsifier is supplied, valve 3 of pipeline 10 opens. Next, water with oil (petroleum products) passes under the lower element 6 of the coalescence filter. The rate of water entering the filter is regulated by the corresponding valve 3 of the inlet pipeline 2. Due to the lower specific gravity of oil 12 compared to the specific gravity of water, the oil rises upward and comes into contact with the surface of the element, while drops of oil slide along the surface of the element and accumulate. Thus, their coalescence occurs. Then, through the hole in the lower element 7, drops of oil flow into the gap between the lower and middle elements. There, a similar process of enlargement of oil droplets occurs near the surface of the intermediate element with further flow of droplets through the holes into the gap between the middle and upper element. After this, oil drops similarly rise through the hole 7 of the upper element 6 into the upper layer of liquid. Since the hole diameter of the lower element is minimal, the middle one is average, and the upper element is maximum, there is a gradual increase in the size of oil droplets.

After filling the coalescence filter, valve 3 of inlet pipeline 2 is closed. Using sight tube 8, the operator sets the oil and water levels. Then, using an inspection tube, through a section of pipeline with a corresponding valve 3 or outlet pipeline 5, he drains the oil (petroleum product) into a separate container. The use of pipeline section 17 or delivery pipeline 5 depends on the levels of oil and water in the coalescent filter 1.

The operator can also determine oil and water levels using optical sensors 18 directly at the workplace. Optical sensors show different refractive indices when oil or water reaches them. Having determined the levels of oil 12 and water 11, the operator opens a section of the pipeline 17 with the corresponding valve 3 or the outlet pipeline 5 to drain the oil (petroleum product) into a separate container.

After this, the operator begins to drain clean water through the dispensing pipeline 4. Purification of wastewater through a coalescent filter allows you to increase the productivity of the installation, eliminate the need for expensive sorbents and filters for purifying water from oil and petroleum products, and also the economic benefits can come from delivering oil for processing.

Preliminary treatment of wastewater makes it possible to prevent mechanical impurities and suspended substances from entering the coalescent filter.

At the same time, the accuracy also increases and the time for determining the levels of oil and water decreases, and the amount of water drained along with oil into a separate container is significantly reduced.

Claims (3)

1. Coalescent filter for wastewater treatment with preliminary filtration of mechanical impurities and suspended substances, including a housing and elements with holes of various diameters, an inspection tube, heating elements, a demulsifier supply pipeline, wastewater supply pipelines, oil removal and clean water, characterized in that that the coalescence filter is additionally equipped with a filter for purifying mechanical impurities and suspended substances, an additional section of pipeline connected to the oil delivery pipeline, as well as two optical sensors with the ability to determine oil and water levels. 2. Coalescence filter according to claim 1, characterized in that the optical sensors are located at a distance of 10-15 cm from each other. 3. Coalescent filter according to claim 1, characterized in that the optical sensors are connected to a receiving device at the operator’s workplace.

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