Mechanical self-cleaning filters (FSMO)

Mechanical self-cleaning filters (FSMO)

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 purified stream is discharged to the filtrate line, providing the required capacity 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. The cleaning process can take place fully automatically or manually. 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.

Video: the principle of operation of the FSMO

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 FSMO 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 can be made in the form of a quick-release bayonet closure or in the form of a standard flat plug with a swivel 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 FSMO filter there is a fitting for connecting the flushing discharge pipeline.

On the side surface of the housing there is a clean filtrate outlet fitting and a flushing discharge fitting. Appropriate technological lines are brought to them.

A filter element is installed inside the FSMO filter.

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

The FSMO 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 FSMo 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 FSMO 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 FSMO filter can be discharged.

The next step is self-cleaning of the filter element. To do this, on a signal from the control cabinet, the damper inside the filter element is rotated. The damper is located approximately in the middle of the filter element. Thus, the flow of the initial medium passes through the filtration in the direction from the inside to the outside in the first part of the filter element, abuts against the damper and then in the opposite direction from the outside to the inside enters the second part of the filter element. 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 damper becomes in a position parallel to the medium flow, the flushing discharge line closes, and the FSMO filter continues to operate in the filtration mode.

Specifications.

The FSMO 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 FSMO filter housing can be from 200 to 1000 mm. Throughput (flow rate of the working medium) from 20 to 6000 m3/h. Working pressure from 0.2 to 4.6 MPa. Position 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.).

As executive mechanisms, electric drives for 220 or 380 V are used on the flushing discharge valve and on the rotation shaft of the flow deflection damper.

The automatic mode of operation of the FSMO filter is provided by the filter control cabinet. It can be individual for each filter or one for a group of filters working together.

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 (FSMO).

* 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".