Mechanical Screens

Rake screens of various measurements are made of stainless steel AISI 304 or AISI 316 on customer demand. Measurements of the rake screens are chosen relying upon required flow rate, wastewater arrangement and measurements of the channels.

The rake screen is a separating mesh comprising of bars introduced into a frame. The bars are produced using primary shapes with a tear drop formed cross segment that improves stream attributes of the filtering mesh. The screen’s filtering mesh can also be made of rectangular or round profile bars.

Bar dispersing in the filtering mesh can change from 5 – 100mm for normal hardware or can be changed exclusively. The rectangular edge comprises of two longitudinal sheets associated by cross shafts. The covered hardened steel chains can be moved along polymer guides installed on the longitudinal sheets of the screen. Chain strain is movable.

Cross rakes are introduced on the chains for cleaning of the filtering mesh. Chains and rakes are impelled by shaft rotation with drive sprockets situated in the screen top segment. The shaft is driven by a motor. At the screen base, the chain is moved along a pilot slider made of a wear safe polymer material. In this way, there are no pivoting parts in the lowered segment of the screen.

The screen is introduced onto a hub of an extraordinary turning prop mounted on the wall of the channel or onto unique stage affixed in the channel while the actual screen can be lifted over the channel for upkeep. In the event that there is an absence of room in a short station without probability of screen lifting, an extraordinary adaptive stage is utilized

Operating Principal

The rake screen gathers and eliminates solids from wastewater that bigger than bar separating. The solids are regularly taken off from the sifting network by the rake moving them to the top edge of the edge. The solids are then eliminated from the rake by methods for a kicker and dispatched along the gravity slide onto a carrier or into squander container. The screen operation periodicity depends on the chosen equipment automation scheme and defined by technological commission results.

Advantages of Bar Screen:

• Protection from mechanical and pressure-driven over-burdens because of high tensile design in correlation with different kinds of mechanized screens
• High hydraulic efficiency is achieved by using tear-shaped bars that cause a pressure gradient to the mesh and across the bar spacing
• The tear molded profile also shields the screen from waste sticking inside the filtering mesh. By utilizing this plan, such blockages can be eliminated by rakes, permitting the screen work uninhibitedly;
• High dependability, accomplished by the shortfall of the turning parts in the submersible part
• Submersible parts like packaging, bars, chains and rakes are made of tempered steel to improve consumption obstruction in forceful conditions of wastewater;
• Improved ergonomics: the practicality of the screen because of openness of the principle units inactivity and screen lifting without demounting.

Automation :

• Screen automation is possible as per various boundaries:
• Timespan.
• Wastewater level contrast upstream and downstream of the screen.
• Any modified program.

Alert frameworks are accommodated the typical activity sign, the crisis stops, the wastewater high level in the channel and others. It is conceivable to move gear status information to a more significant level automated process control framework relying upon the customer’s necessities. The screen is provided with a security device jet lever to evade harm to the screen, for example, chain extending or breaking. The security gadget and stops the screen activity in case of any jam or mechanical hindrance to the chain development. Light and sound alerts turn on all the while when the safety device activates. The screens along with a conveyer, compacting press and slide doors are remembered for an elite complex for mechanical wastewater treatment. Outfitting the control system with programmable modules makes it conceivable to coordinate complex sub systems into one system with a common control centre and remote dispatching.

Screens are manufactured from stainless steel AISI 304 or AISI 316 on customer demand. The movable and endless filtering mesh consists of hooks and is installed on the screen frame. Filtering mesh openings are 5mm wide by default, but can be adjusted on customer demand. The rectangular frame consists of two longitudinal boards connected by crossbeams. The filtering mesh moves along polymer guides installed on the longitudinal boards of the screen, and is driven by a shaft with drive sprockets located on the top part of the screen.

The shaft is driven by a geared motor. Filtering mesh tension can be adjusted. Wash water nozzles and a drum with radially located brushes are placed on the driven shaft of the geared motor. This motor is installed on top of the screen frame and is designated for the filtering mesh hooks cleaning.

Operating Principle

• The hook type screen retains and removes solids of which the size exceeds that of the filtering mesh openings from the wastewater. Collected solids are moved in an upward direction to the discharge zone by means of the hooks. Here it is discharged into the transporter or waste bin. After the waste is discharged, cleaning of the filtering mesh is performed by wash water from the nozzles, followed by the revolving brushes. In addition, the previous hook line cleans the next hook line at the moment of its overturn.
• The screen operation periodicity depends on the equipment automation scheme.
• Due to the special design of the filtering mesh, a contamination layer is generated onto the working surface and creates an additional filtering effect which allows catchment of particles with sizes less than 5 mm.

Automation

• Screen automation can be done according to different parameters: Wastewater level difference upstream and downstream of the screen.
• Any customized program.
• Alarm systems of the normal operation indication, the emergency stops, the wastewater top level in the channel and others are provided. It is possible to transfer equipment status data to a higher level automated process control system depending on the client’s requirements.
• The screen is supplied with safety device to avoid damage to any screen components.

The safety device stops the screen operation when bulky waste ingress the filtering mesh, or when any other object blocks free plate movement. Light and sound alarms turn on simultaneously when the safety device is active. The screens, together with a conveyor, compacting press and slide gates, are included in a high-performance complex for mechanical wastewater treatment.

Equipping the control system with programmable modules makes it possible to integrate complex sub systems into one system with a common control center and remote dispatching.

Advantages

• Fine mechanical wastewater treatment is achieved due to the narrow filtering mesh spacing, as well as the contaminants layer formation on the screen’s steps Special design of the hooks makes the filtering mesh self-cleaning.
• Reliable and easily operated
• Step screen is manufactured from stainless steel AISI304 or AISI316 (on customers demand) which makes the equipment corrosion resistant

Scope of Application of Screw Screens

• Municipal wastewater treatment
• Paper and Pulp industry
• Meat processing industry
• Vegetable and fruit processing plants
• Food industry

Features

• The primary element of the screw screen is its usefulness. It isolates medium and little waste from municipal and industrial wastewater, at that point performs washing, pressing and transportation of the screenings to the garbage removal tank.
• An opened or punctured sifter is introduced at the lower part of the screen. As the wastewater goes through the strainer, the waste is held on the separating surface. The screw is furnished with a brush to clean the strainer in the filtration region. In the upper piece of the screen, there are territories for the screenings washing and pressing.
• Because of the coordinated screenings washing capacity, natural mixtures stay in the wastewater, which adds to the biological treatment measure.
• The shaftless screw prevents blockage, obstructing or sticking of the screen, in any event, when working with stringy materials.
• The utilization of a punctured sifter with little openings takes care of the issue of holding even difficult-to-get impurities, like hair.
• The screen can be outfitted with a gadget for dumping washed and dewatered squander into polyethylene packs, which isn’t just incredibly helpful for additional transportation of waste, yet in addition, forestalls the spread of odors.
• The design solves the issues related with the activity of a huge piece of the extra hardware for wastewater treatment, for example, there are no mind-boggling systems and parts that require consistent and work concentrated support.
• RVO screw screen can be effortlessly coordinated into the current complex of treatment offices and synchronized with different sorts of equipment.
• The screens are intended for use in wastewater with pH = 6.5÷8.5.

The durability of the Screw Screens

• All work is finished by the screw, so there is no critical number of rotating parts. This increases the reliability and durability of the screen.
• The screw is made of wear-safe carbon steel, and a self-cleaning strong brush is introduced nearby the channel sifter.
• The utilization of stainless steel (AISI 304, AISI 316) in the unit gives its strength, which is vital for work in an aggressive wastewater climate.

Application Features of Step Screens:

• Fine wastewater treatment – least dispersing width is 3 mm.
• High throughput capacity
• Self-cleaning separating surface design
• Air-assisted fomentation arrangement of sand silt.
• Step Screen
• Step Screen

Advantages and Benefits of the Step Screens:

• The design adjusts to practically any installation site. At times, blocked holes can be impeded by rubber sealings.
• Activity in the mode of ceaseless lifting and transportation of screenings.
• Narrow slot width and the filtration of the stream by the “cover” of the lifted screenings, which altogether builds the partition effectiveness.
• Self-cleaning of plates without the utilization of assistant components, brushes or washing with water.
• Prevention of screenings’ falling once again into the channel because of the diminished spacings of 1 mm nearby over the channel.
• Low amiability to sand and rock.
• Simple substitution of the sifting surface if there should be an occurrence of harm.
• The utilization of a dependable worm gear engine from the world brand, NORD Drive Systems.
• Slight sheet metal plates with a thickness of 2-3 mm give a high throughput limit of the screen.
• Evacuation of fine silt utilizing a punctured pipe. The pipe is introduced at the lower part of the screen and is utilized to work up silt that can be gathered before the screen.
• Coordination into existing offices for wastewater treatment. Alternatives of robotization and synchronization with different sorts of equipment.
• Mechanical and electrical over-burden protection incase if blocking,

Durability of Step Screens:

• The use of AISI 304 or AISI 316 stainless steel. Additional anti-corrosion treatment – volume etching and passivation.
• Strong housing that is resistant to damage, inaccurate installation or rough transportation conditions.