Environment and Energy

Green Valve

Energy Recovering control Valve
Stefano Malavasi - Department of Civil and Environmental Engineering

Energy harvesting from dissipation processes during flow control is a challenge for many different applications. Common usage of many plants and systems requires control valves to dissipate overpressures. GreenValve is an innovative control device designed to control the flow and harvest the energy that is normally wasted during the throttling process. A vertical axes water turbine resides within the valve body to improve regulation efficiency and recover part of the energy that would be dissipated.

The core technology, developed by the department of Civil and Environmental Engineering, consists in a spherical common valve modified in order that the rotational axis of the turbine is the same as the valve’s stem. The opening of the valve, commanded through the stem, allows setting up the desired conditions of pressure or flow in the pipeline.

The rotor, consisting of a set of blades, is connected to the transmission shaft and is designed to rotate in a continuously under the flow. The rotational axis can be connected to an electric generator to provide energy.

The produced energy is used for the management of the valve itself. The energy in excess can  power monitoring devices or in some cases, it can be lead in to grid.

The laboratory tests allowed the evaluation of the valve behavior highlighting a remarcable similarty to the most diffuse control valves. Furthermore the evaluation of the cavitation characteristics demonstrated a good resistance to the phenomenon, which represents a weakness in the regulation field, in noise generation, vibrations and loss of efficiency of the devices.

The materials of the rotor depend on the fluid typology for which GreenValve is optimized: gas or different types of liquids.

GreenValve keeps separated the speed of the turbine rotation from the regulation of the flow, and consequently the function of regulation is separated from the recovery of energy. This characteristic allows a simple optimisation of the system in terms of energy recovery and regulation in any working condition, also when the turbine is inoperative.

A GreenVale prototype has been tested in the Hydraulic Engineering of Politecnico di Milano.

GreenValve can substitute existing control valve without the installation of further components in the pipeline or any other change in the systems operating conditions. The Green Valve can be applied in industrial plants and distribution networks in different fields (electricity production, water, oil & gas, etc.). This innovative valve can replace the common control valves or installed in stand-alone mode giving the possibility to recover energy.