Valves for Turning Waste into Energy

Pinch Valves Assist with Waste to Energy Plant

Our waste is not wasted at this particlar Energy From Waste (EFW) site, where the company are using AKO Pinch Valves to aid with the flow of product into a mixing tank.

The company’s EFW plants’ use mainly municipal solid waste (MSW) as a fuel to keep the furnaces under fire in order to incinerate the waste. This then heats up water in the boilers that produce high pressurised steam, that is used to turn blades in a turbine that feeds that energy into a generator to convert that energy into electrical power.

The excess electricity produced is distributed to the national grid to power businesses and homes.

The EFW plants consist of 2 parallel incineration streams, each comprising a furnace, boiler and flue gas treatment. The common systems to both incineration streams consist of cranes, water treatment plants,  steam turbine generator, air cooled condenser, ash and lime systems.

The exact media passing through the Pinch Valves are Quicklime, Calbux, Biocal and Limbase (as pictured, showing the Pinch Valve partially open). Each of these media are approx 25 degrees, passing through the valves at a free flow pressure.

The valves for turning waste into energy are installed vertically above a mixing tank, and are normally closed; opening to allow lime flow into a lime slurry mixing tank.

Operating at around 15-20 cycles per day, this Pinch Valve uses 2.5 Bar air pressure to open the sleeve inside the Pinch Valve casing.

The EFW Process

Waste is fed by overhead cranes into 2 feed chutes, one for each incinerator stream. A ram-feeder pushes the waste into the furnace, where it is burnt as it travels down the inclined moving grate system. The residue ash on the grate system is discharged into a water quench system, where it is cooled. This bottom ash is transported on a conveyor system through a ferrous belt magnet to extract ferrous metal for recycling. The remaining bottom ash is transported to a bottom ash recycling facility.

Pinch Valve for Turning Waste into Energy: Performance

The environmental company have been using AKO Pinch Valves for 25 years. They have never experienced any problems, with Michael O’Donnell, the on site Control & Instrument Engineer expressing that the Pinch Valves are suitable for the application.

This site uses pipework of 150mm diameter, and therefore DN150 sized Pinch Valves for turning waste into energy are supplied to suit. The rubber sleeve inside the Pinch Valve usually lasts around 6 months, although sometimes sooner if overheating occurs inside the mixing tank.

The rubber sleeve is simply repaired as needed, with the help of AKO’s fitting kit and assembly videos.