RU48513U1 - FILTER BLOCK FOR SEA WATER PURIFICATION FROM WEIGHTED SUBSTANCES AND OIL ON OIL AND PETROL PLATFORM - Google Patents

Abstract

The proposed utility model relates to the equipment of oil drilling platforms, and in particular to the means of post-treatment of sea water used in oil production technology. This technical solution is aimed at improving water quality, improving operational characteristics and ensuring environmental safety. The essence of the utility model lies in the fact that the filter unit is equipped with an electrolytic chlorination unit for sea water, consisting, for example, of an electrochemical chlorine generator and a metering pump, the discharge pipe of which is connected to the inlet collector, and a forced chemical washing unit, consisting, for example, of a reactor solvent, heater and circulation pump and configured to alternately connect it with the cavity of each filter housing. The chemical washing unit is located in the space between the inlet and outlet manifolds. In addition, an additional nozzle is installed on each filter housing with the possibility of alternately connecting it either to an external compressed air system or to a drainage system, and the additional nozzle is placed from the condition Н ₁ <Н ₂ , where:

H ₁ - the distance from the pipe to the pipe baffle;

H ₂ - the distance from the pipe baffle to the first (highest) through hole in the pipe of the filter element. The drainage system is also equipped with a quick-closing valve.

It is also significant that the filtering elements are made of titanium alloys in the form of a pipe corrugated in the transverse direction with ridges and hollows longitudinal along its length, and through holes located in the hollows, over which a wire is wound, partially flattened in diameter, moreover, on one of of two planes formed during flattening, transverse grooves (steps) of 0.05 ... 0.1 depth from the diameter of the wire are periodically made. The wire is wound tightly on the pipe, turn to turn so that the turns touch each other along the flattening plane, and the transverse grooves form filter slots of a fixed size. The overall dimensions of the filtering elements are made based on the ratio: L / D≥15, where: L is the length of the filtering element from the pipe baffle to the edge of the free (not connected to the pipe baffle) end; D is the outer diameter of the element along the turns of the wire.

Description

The proposed block of filters for the purification of sea water from suspended solids and oil on an oil drilling platform (hereinafter referred to as the Block) refers to the technology for purifying sea water at facilities operating in extreme environmental conditions, for example, in ice beyond the Arctic Circle.

The need for additional purification of sea water is caused by the fact that sea water is used in oil production technology, for example, to fill manifolds (special storage tanks), as a cooling medium for various production equipment, in sanitary systems, etc., and natural sea water in the water area adjacent to the platform heavily contaminated with suspended solids and petroleum products. Operating conditions dictate increased requirements for water treatment equipment in terms of its operability when exposed to low ambient temperatures and vibration loads from mechanisms operating on the platform, reliability, environmental safety, and other requirements.

Known cartridge filters for water purification from dispersed impurities (see, for example, the catalog "Filters for liquids", published by TsINTIkhimneftemash, Moscow, 1990, p.20-34). The filter cartridges are a perforated tube over which a filter cloth sleeve is pulled. Filters are used individually or in blocks of several filters equipped with an automation and control system.

Also known are capacitive filters operating under pressure, containing a cylindrical body and filter loading, for example, silica sand, located between two drainage gratings, one of which is movable (see ibid., Pp. 38-39).

Such filters are not suitable for treating seawater contaminated with suspended solids and oil products, due to the low degree of

cleaning and the impossibility of effective regeneration during operation on the oil drilling platform.

The closest analogue (prototype) of the claimed technical solution is the Metrol ^® Sea-Sereen ^® filter unit of the English company "PETRECO" (see information on the website WWW.PETRECO INTL.СОМ and the company's brochures). The block is used in seawater treatment systems, including oil drilling platforms. The filter unit operates on the principle of coarse mechanical filtration on the mesh filter elements and their periodic regeneration in countercurrent source water.

The unit includes a number of hydraulically interconnected filters in the form of vertical cylindrical housings with removable covers and nozzles for supplying and discharging water, inside of which filtering elements (drums) are fixed at the lower end of the pipe wall. Elements are made in the form of a perforated cylindrical pipe with a blind upper and open lower end, on the surface of which a triangular-section wire is wound. The wire is oriented so that the base of the triangle is adjacent to the surface of the perforated pipe, and the vertices of the triangles in the cross section of the wire and, accordingly, the wedge-shaped gaps between the turns are facing outward with respect to the filter element. The wire is wound with a gap between the turns forming filter slots, for example, 80 microns. In the center of the filter element is a vertical electric drive hollow shaft to which scrapers are attached adjacent to the inner surface of the element and connected to the shaft cavity. The shaft cavity, in turn, is connected to the drainage system. The filter unit is also equipped with collectors for supplying and discharging water, electromagnetic valves, a differential meter, drainage and ventilation systems.

The source sea water is supplied to the unit through the inlet collector, then into each housing under the pipe baffle, inside the filter elements. Passing through the filter slots in the direction from the inside of the element to the outside, the water is purified and discharged through the outlet manifold for consumption. At the same time, mechanical impurities larger than 80 μm are retained on the inner surface of the element near the filter slots.

As the filter elements become clogged by the differential flow signal, the regeneration system turns on: an automatic valve opens on the flushing water discharge line and at the same time the hollow shaft electric drive turns on: the scraper system begins to move along the inner surface of the filter elements. Due to the pressure drop (outside the filter elements, i.e. in the housing, the working pressure of sea water acts, and inside - in the zone of abutment of the scraper - atmospheric), pollution particles from the inner surface of the element are sucked into the hollow shaft, and from it are discharged into the discharge system wash water. After doing

one full revolution, the shaft drive is automatically turned off, and the solenoid valve on the flushing water discharge line closes. In this case, the entire working surface of the filter element is cleaned. Next, the work cycle is repeated.

The filter block of the PETRECO company has the following disadvantages:

1. Insufficient degree of water purification from dispersed impurities and oil products, which is due to the purely mechanical principle of particle retention applied in the unit.

2. Insufficient specific (per unit of the unit’s overall volume) dirt capacity of the filter element and, as a result, the comparatively low throughput of the Unit, which is explained by the accepted direction of water flow through the element (from the inside to the outside) and the need to place a system of scrapers and a drive shaft inside the filter element.

3. The insufficient degree of regeneration of the filter elements, due to:

- the gradual accumulation of sediment in the wedge-shaped filter slots, especially with a backwash period,

- rigidity (inflexibility) of the frame of the filter element,

- lack of compressed air system,

- the lack of factors that destroy oil.

4. The structural complexity of the block, which is associated with the use of movable mechanisms inside each filter element and electric drive systems.

5. The increased consumption of washing water.

6. The possibility of fouling of the Block by marine microorganisms.

7. Environmental pollution by oil, especially during backwashing.

The technical result expected from the use of the claimed utility model is the ability to:

- improve the quality of sea water purification,

- increase the dirt capacity of the filter elements and the specific throughput of the Unit,

- to increase the efficiency of the regeneration of the filter elements and to protect the Unit from fouling by marine microorganisms,

- simplify the design of the block,

- reduce the flow rate of wash water,

- reduce environmental pollution by oil.

The indicated result is achieved in that the filtering elements are made of titanium alloys in the form of a pipe corrugated in the transverse direction with ridges and hollows longitudinal in its length, and through holes located in the hollows, over which a wire is wound, partially flattened in diameter, and on one from two planes formed during flattening, transverse grooves (steps) of 0.05 ... 0.1 depth from the diameter of the wire are periodically made. The wire is wound tightly on the pipe, turn to turn so that the turns touch each other along the flattening plane, and the transverse grooves form filter slots of a fixed size. In this case, the overall dimensions of the filter elements are made based on the ratio:

L / D≥15, where:

L is the length of the filter element from the pipe baffle to the edge of the free (not connected to the pipe baffle) end;

D is the outer diameter of the element along the turns of the wire.

In addition, the Unit is equipped with: an electrolytic chlorination unit for sea water, consisting, for example, of an electrochemical chlorine generator (ECG) and a metering pump, the discharge pipe of which is connected to the inlet collector, and a forced chemical washing unit, consisting, for example, of a solvent reactor, a heater and a circulation pump and configured to alternately connect it to the cavity of each housing. The chemical washing unit is located in the space between the inlet and outlet manifolds. Each cylindrical housing has an additional nozzle with the possibility of alternately connecting it either to an external compressed air system or to a drainage system, and the additional nozzle is placed from condition Н ₁ <H ₂ , where:

H ₁ - the distance from the pipe to the pipe baffle;

H ₂ - the distance from the pipe baffle to the first (highest) through hole in the pipe of the filter element.

The drainage system is also equipped with a quick-closing valve.

The proposed utility model of the Block is illustrated by drawings, which depict:

figure 1 is a schematic diagram of a hydraulic circuit block,

figure 2 - filter housing and its elements.

The filter block (FIGS. 1, 2) includes a series of hydraulically interconnected filters F1 ... F5 in the form of cylindrical housings 1 with removable covers 2 and nozzles 3 and 4 for the inlet and outlet of sea water. Inside the housing there is a pipe baffle 5, on which filter elements 6 made of titanium alloys are vertically fixed. Each element is made in the form of a transverse corrugated pipe 7 with longitudinal ridges and depressions along its length and through holes 8 located in the depressions. Top row through

holes located at a distance of H ₂ from the tube plate. On top of the corrugated pipe is tight, turn to turn, a wire 9 is wound, partially flattened in diameter, moreover, on one of the two planes formed during flattening, transverse grooves (steps) 10 of a depth of 0.05 ... 0.1 of the diameter are periodically made wire. The turns touch each other along the flattening plane, and the transverse grooves form through holes (filter slots) 11. For winding, for example, titanium wire with a diameter of 0.87 mm can be used. In this case, the flattening is performed at 10 ... 15% of the initial diameter, for example, from a diameter of 0.87 mm to a size of 0.77 mm. The depth of the transverse grooves is, for example, 10% of the thickness of the tapered wire, i.e. in our example - 0.07 ... 0.08 mm. After winding such a wire, the guaranteed width of the filter slots and, therefore, the filter fineness is 80 microns.

The lower end of the filter element 6 is sealed, and the upper end of the element is rigidly fixed to the pipe wall so that the cavity of the housing 1 is connected to the cavity of the cover 2 through the filter slots 11. The length of the element L is selected from the ratio L / D≥15, where:

D is the diameter of the filter element along a wound wire.

The specified ratio allows the lower (non-fixed) end of the filter element to vibrate during the "shock flushing", as well as when exposed to external vibrations from the mechanisms operating on the drilling platform.

An additional nozzle 12 is installed on each housing 1, to which a compressed air system is connected through valve 13 and a drainage system through a quick-closing valve (BZK) 14. The nozzle 12 can be alternately connected either to a compressed air pipeline or to a drainage system. The location of the pipe 12 on the housing is selected from the condition H ₁ <H ₂ , where:

H ₁ - the distance from the pipe to the pipe baffle;

H ₂ - the distance from the pipe baffle to the very top row of through holes in the pipe 7 of the filter element 6.

Cases 1 are interconnected by collectors of seawater supply 15 and seawater discharge 16, equipped with shutoff valves, for example, rotary valves 17.

To purify sea water from oil and prevent fouling of the Block by marine microorganisms, an electrochemical chlorination unit 18 is provided, including, for example, an electrochemical chlorine generator (ECG) 19 and a metering pump 20 connected to the inlet manifold 15c using pipelines and shutoff valves 21. The ECG operates on

the principle of the formation of a solution of sodium hypochlorite (a strong oxidizing agent) and gaseous products of electrolysis (oxygen, hydrogen, chlorine, etc.).

The Block is also equipped with a chemical washing unit 22, which is necessary for periodic complex processing of the Block, as well as for eliminating strong contaminants entering the Block in emergency situations, for example, during abnormal oil discharges into the fishing area. The assembly includes, for example, a solvent reactor 23, a solution heater 24, a circulation pump 25, pipelines and fittings 26. Acids, alkalis, surfactants, etc. can be used as a chemical solution. A chemical washing unit is located in the space between the collectors supply and removal of sea water 15 and 16, which is dictated by the most rational layout solution: this space in the Block is not occupied by any other equipment. In addition, the length of the piping for connecting the node 22 with the housing 1 in this case will be minimal. The electrochemical chlorination unit can be placed in the same space, or in a separate specially equipped room.

The block also includes auxiliary cranes 27 for ventilation and 28 for draining the housings 1. The cranes can be manual or automatic. To measure the hydraulic resistance of the Unit, the differential meter 29 is used. The unit is mounted on a single frame (not shown in Fig.).

The filter unit operates as follows (Fig.1 and 2). Sea water containing suspended solids and oil pollution from collector 15 through pipe 3 under a pressure of 1 ... 1.5 MPa is supplied to housing 1. Passing through unit 18, sea water is enriched with a strong oxidizing agent - sodium hypochlorite with an active chlorine concentration of 5. ..10 mg / l and gaseous electrolysis products that immediately interact with oil pollution. As a result of chemical oxidation processes, most hydrocarbons are denatured and converted into inorganic substances, and gaseous substances, acting as a flotation agent, participate in the flotation of undestructed oil molecules, their aggregation and coalescence (sticking). At the same time, marine microorganisms that contribute to the biological fouling of surfaces in contact with sea water are suppressed by a strong oxidizing agent.

In the housing 1, sea water passes through the filter slots 11 of the elements 6, is cleaned of mechanical impurities and oil particles larger than 80 microns in size and enters the lid cavity 2, from where it is diverted to the consumers through the pipe 4 and the collector 16. Undestructed particles of oil float and accumulate in the space between the lower surface of the septum 5 and the upper row of through holes 8 in the filter element 6.

As the filter elements 6 become dirty, the hydraulic resistance of the filters increases, the differential meter 29 is triggered, and the unit is automatically transferred to the regeneration mode. Regeneration is carried out according to the principle of “shock flushing”. The inlet and outlet of the water using the shutters 17 is blocked. The crane 27 opens, and then the crane 28, and the housing 1 begins to drain. The water pressure in the housing drops from the operating value (1 ... 15 MPa) to atmospheric values. In this case, intense degassing occurs - the release of dissolved chlorine from the water and its transition to a gaseous state. Chlorine gas accumulates in the cavity under the cover 2. The discharge of water continues until the water level in the housing reaches the edge of the nozzle 12. Next, the valve 27 closes and the valve 13 for supplying compressed air opens. Under a working pressure of compressed air of 0.5 ... 0.6 MPa, water enriched in oil from the annulus is partially displaced into the cavity of the cover 2 and comes into contact with chlorine gas. In this case, the oil film under the direct influence of a strong oxidizing agent is destroyed, passing into an inorganic substance.

The flow of water from the cavity of the housing 1 into the cavity of the lid 2 continues until the water level in the housing reaches a distance of H ₂ , after which the compressed air begins to bubble through the openings 8 and the air pressure in both cavities is equalized.

Then begins the actual "shock flushing": the high-speed valve 14 opens, and the air pressure under the pipe baffle 5 almost instantly drops to atmospheric value. A water column located in the lid cavity and in the upper part of the filter element pipe rushes down under the working air pressure, creating a water hammer in the cavity of each filter element. The duration of the water hammer is a fraction of a second, until the air pressure above the tube plate is equal to atmospheric, and all the water from the lid cavity merges into the body.

Under the influence of a water hammer, a “membrane” formed by a tightly wound wire and dispersed particles stuck in the filter slots comes into oscillatory motion, due to which the filter elements are cleaned of impurities. The ejection of particles from the cracks is also facilitated by the presence of a strong oxidizing agent in the water, which chemically destroys the oil film and reduces its adhesion to the surface of the filter element.

The action of water hammer during "shock flushing" also causes the vibration of the filter element along its entire length, moreover, the vibration increases with distance from the tube plate. The free end of the filter element experiences maximum vibration. So

Thus, the combined action of all these factors (water hammer, vibration of the “membranes” and filter elements in length, the presence of a strong oxidizing agent in the water that destroys oil pollution) and ensures efficient regeneration of the filter elements.

Contaminants discharged from the surface of the filter elements accumulate in the lower part of the housing 1, and then are discharged into the sewer when the filter is drained through the tap 28. After the housing is drained, it is switched to the operating mode, as described above.

Chemical washing of the Unit is performed as a routine operation for preventive purposes, or in the case when regular “shock washing” does not reduce the hydraulic resistance of the filters to the required level. Filters are chemically washed one after the other. During chemical washing, one filter is removed from the filtering mode, other filters continue to work.

Chemical washing is carried out in the following order. In the solvent reactor 23, the necessary chemical solution is prepared (alkali, acid, surfactant, etc.). Heater 24 and a circulation pump 25 are turned on. Using pipelines and shutoff valves 26, the solution flow is circulated in a closed loop: reactor - heater - housing - reactor. The operation can be performed automatically, by timer. In the process of chemical washing with a warm (40 ... 60 ° C) solution, the filter elements are completely cleaned of impurities, after which the filter housing is drained with the simultaneous discharge of impurities into the sewer. Further, subsequent neutralization of effluents is possible.

It is also significant that during chemical washing, the filter housing and filter elements are affected by vibration from mechanisms operating on the oil drilling platform, which ensures their continuous self-cleaning and increases the periods between rinses. At the end of chemical washing, the filter switches to the operating mode, and then the chemical washing of the next filter is likewise carried out.

A comparative analysis of the advantages of the claimed Block in comparison with the Block of PETRECO is presented in the table. The calculated data are based on the studies of the Block for the Prirazlomnaya ice-resistant oil drilling platform. From the table it follows that the claimed Block exceeds the analogue in most of the comparison parameters, which indicates the achievement of a technical result.

Table Options The filter block of the claimed Filter block "PETRECO" Productivity, cubic m / h 13100 12500 Filter fineness, microns 80 80 The oil content in the filtrate (total organic carbon), mg / l 0.5 ... 5.0 More than 15 Specific dirt capacity, kg / cubic meter of overall volume for the filter cycle period 11.5 7.5 Specific throughput, cubic m / h / cbm overall volume 99.3 65.1 The efficiency of regeneration,% 90 ... 95 60 ... 70 Dry cleaning efficiency,% 95 ... 98 0 (no dry cleaning) Flushing water consumption,% of productivity 0.5 ... 1.0 3.5 ... 5.0 Unit weight, kg: - in a dry state 15500 34000 - in working order 39,000 78000 Overall volume (length × width × height), cubic meter: 132.0 192.0 Protection against biological fouling of the block by marine organisms provided not secured Protecting the environment from oil provided not secured

Claims (4)

1. A filter unit for purifying seawater from suspended solids and oil on an oil drilling platform, including a series of cylindrical housings hydraulically interconnected with removable covers and water inlet and outlet pipes, in which filter elements are arranged in the form of spirally wound connected at one end to the pipe baffle on a perforated pipe of non-circular wire, water supply and drain manifold, shutoff valves, differential meter, drainage and ventilation systems, characterized in that the filtering pipe elements placed under the pipe wall, is made corrugated in the transverse direction with longitudinal ridges and troughs along its length and through holes located in the troughs, while the wire is partially flattened in diameter and wound tightly on the pipe, turn to turn so that the turns are in contact with each other each other along the plane of flattening, moreover, on one of the two planes formed during flattening, transverse grooves (steps) are periodically made. 2. The filter unit according to claim 1, characterized in that on each cylindrical body an additional nozzle is installed with the possibility of alternating connection with either an external compressed air system or with a drainage system, and the additional nozzle is placed from the condition H ₁ <H ₂ , where H ₁ is the distance from the pipe to the pipe wall, H ₂ is the distance from the pipe wall to the first (highest) through hole in the filter element pipe, and the drainage system is equipped with a quick-closing valve. 3. The filter block according to claim 1, characterized in that it is equipped with an electrolytic chlorination unit for sea water, consisting, for example, of an electrochemical chlorine generator and a metering pump, connected by its pressure pipe to the inlet collector, and a forced chemical washing unit, configured to alternately connecting with the cavity of each body and consisting, for example, of a solvent reactor, a heater and a circulation pump. 4. The filter block according to claim 1, characterized in that the filter elements are made, for example, of titanium alloys.