Mechanical self-cleaning cascade filters (FSMOk)

Mechanical self-cleaning cascade filters (FSMOk)

Can be used as a stage of mechanical cleaning. The main feature is the possibility of periodic self-cleaning of the filter from retained contaminants without stopping the filtration process. When the filter is switched to the self-cleaning mode, the flow of the initial medium inside the body is redistributed. Part of the stream that has been purified is diverted to the filtrate line, providing the necessary performance for the finished product. And part of the flow is directed to a special drainage fitting, taking with it the contaminants trapped by the filter element and cleaning the working surface of the filter. To completely clean the filter, by adjusting the shutters, a backwash flow is created that completely cleans the device of impurities. The cleaning process is controlled by the control cabinet program and can be fully automatic or manual.

Thus, for the operation of the filters, there is no need to organize a separate line for supplying wash water, there is no need for a tank for storing wash water and a special pump for supplying water for backwash, as it is required for classic mechanical filters. In some cases, you can even do without installing a backup filter.

A distinctive feature of FSMOk  filters is their respectively small size  and the ability to combine them into a cascade. Simplicity of a design allows to carry out their repair and maintenance easily.

Function. As usual they are used in purification schemes where it is required to process small and medium volumes of contaminated media:

1. Purification of cooling water circulating cycles;
2. The first stage of mechanical purification of the source water of large energy facilities (CHP, state district power station, nuclear power plant);
3. Purification from mechanical impurities in the processes of preparation of drinking water;
4. Wastewater treatment of various industrial processes;
5. Preliminary purification of water before supply to pumping units, heat exchangers, nozzles or other process equipment;
6. Preparation of water for the preparation of various solutions and suspensions;
7. Purification of foreign inclusions of technological solutions in chemical, food and other industries;
8. Purification of hydrocarbon impurities in the process of processing and pumping.

Description of the structure. Mechanical self-cleaning filters consist of:

• body;
• filter element;
• technological fittings;
• pressure sensors;
• flow sensors;
• shutoff and control valves;
• automatic control cabinet.

The FSMOK filter housing is cylindrical steel made of sheet steel or pipe. An elliptical plug is welded at the bottom. In the upper part there is a flat cover for maintenance of internal structural elements (filter element).

The cover is made in the form of a standard flat plug with a rotating mechanism.

Depending on the diameter of the filter and the customer's requirements for the location of the device on the body, support elements are provided: legs, racks or saddle supports.

In the center of the lower bottom of the FSMOK filter there is a fitting for connecting the flushing discharge pipeline.

On the side surface of the body there is a fitting for supplying the initial medium and a fitting for removing the filtrate. Appropriate technological lines are brought to them. At the request of the customer, the direction of the inlet and outlet fittings can be located at different angles.

A filter element is installed inside the FSMOK filter.

Shut-off and control valves with electric drives are installed on the fittings.

The FSMOK filter operation control cabinet can be located separately on a special rack or mounted on the filter housing using a special bracket.

Cable lines are protected from mechanical damage by special sleeves and securely fastened.

Pressure sensors are installed on the supply line of the initial solution and on the line of the filtrate outlet into special blockings.

Operating principle. The operation of the FSMOk filter consists of the following successive stages:

• purification of the initial solution from mechanical impurities;
• periodic discharge of accumulated pollution;
• self-cleaning filter element.

The initial medium containing impurities (mechanical inclusions) enters the FSMOK filter under pressure through the upper side fitting. Then the initial medium enters the filter element, where the liquid flow passes from the inside to the outside.

The side surface of the filter element has holes or slots of a certain size, which allow you to trap contaminants contained in the original stream. Thus, contaminants are retained and accumulated on the inner surface of the filter element, and a clean stream exits outside the filter element.

The purified medium is discharged through the filtrate pipe.

As pollutants accumulate in the filter, the hydraulic resistance of the filter gradually increases. Which is fixed using pressure sensors. The signals from the sensors are transmitted to the control cabinet and processed by the controller. When a certain value of the pressure difference between the inlet and outlet of the filter is reached, the FEL cleaning step occurs without stopping the filtration process.

First, the dirt accumulated by the filter element is discharged. To do this, the flush water discharge line is opened. In this case, part of the liquid flow rushes into the flushing discharge pipe, taking with it the contaminants trapped by the surface of the filter element. The filtration process continues without a significant reduction in filter performance. Thus, up to 70-80% of the contaminants retained by the FSMOK filter can be discharged. After direct-flow discharge of contaminants from the inner surface of the filter nozzle, the slots are backwashed by partially closing the shut-off and control valves of the inlet fitting. The total cleaning time is from 25 to 90 seconds (depending on the characteristics of the technological process). Due to this, an intensive washing of the filter surface of the filter element occurs in the direction of the reverse filtration. The contaminants remaining after the preliminary discharge are washed off the surface of the filter element and carried away to the flushing discharge line. The operation of the filter and obtaining a clean filtrate does not stop. This step can take up to 2 minutes. Further, the FSMOK filter continues to work in the filtering mode.

Specifications.

The FSMOK filter body is made of carbon low-alloy steel.

The material of the filter element is stainless steel or titanium. Filter nozzle is manufactured according to the TEKO-SLOT technology using a wire of a special triangular profile.

The filtration rating (filter slot) is 100 to 4000 microns (0.1 to 4 mm).

The diameter of the FSMok filter body can be from 200 to 600 mm. Throughput (flow rate of the working medium) from 150 to 2000 m3/h. Working pressure from 0.2 to 4.6 MPa. Location on the pipeline - vertical or horizontal.

Protective coatings. A special anti-corrosion coating is applied to the surface of the filter in contact with the environment. Types and brands of coatings correspond to characteristics of an aggressive environment (epoxy, polyurethane, gumming, etc.)

The outer surface is painted in a standard primer-enamel in the manufacturer's corporate color or at the request of the customer using special schemes for protecting equipment from collisions and grouping color solutions for users (ROSNEFT, LUKOIL, SIBUR, GAZPROM, etc.).

Automatic mode of operation of the filter FSMOK recording of the filter control cabinet. It can be selected on each filter or in one filter group.

Technical requirements:

• Working pressure of the source medium: from 0.2 MPa.
• Operating temperature of the medium: from 0° to 80°С.
• The presence of a hydrolock on the flushing discharge pipeline.

Classification and technical characteristics of the manufactured mechanical self-cleaning cascade filters (FSMOk).

* depends on the placement of the body in space

** throughput nominal…..maximum

Design, manufacture, acceptance and operation of FSMO filters is carried out in accordance with the requirements of TU3683-009-33513134-2012 “Filtration equipment. Specifications"; GOST 34347-2015 "Steel welded vessels and apparatus"; PB 03-584-03 "Rules for the design, manufacture and acceptance of steel welded vessels and apparatus"; PB 03-576-03 "Rules for the design and safe operation of pressure vessels".