Software helps rice waste contribute to Kyoto

Byproducts from Riso Scotti food processing in Italy are put to good use in the company's energy plant at Pavia rather than adding further waste into the local environment.

Byproducts from Riso Scotti food processing in Italy are put to good use in the company's energy plant at Pavia rather than adding further waste into the local environment.

Instead, the biomass is turned into useful electrical energy which is exported into the national grid system.

Cimplicity Plant Edition and GE Fanuc PLCs are used to provide the vital role of monitoring and controlling the plant, which effectively contributes to the European Union's commitment to the Kyoto agreement.

Riso Scotti is a major international producer and supplier of rice products.

It produces a wide range of rice for risottos, soups, sauces, puddings and biscuits.

It uses rice which is extensively grown across the north of Italy, particularly in the Po Valley and in the Veneto region.

Riso Scotti also imports rice from Asiatic countries such as India, Pakistan and Thailand.

The combined heat and power station constructed by Riso Scotti in Pavia is an important example of how it is possible to produce energy from alternative sources which often would be lost in other processes.

In the Pavia plant, the "fuel" comes from biomass (a term which refers to any kind of material of organic, mainly vegetable, origin) rather than traditional sources such as coal, petroleum and natural gas.

The generation of energy from the combustion of biomass, unlike the generation of energy from the combustion of fossil fuels, releases significantly less carbon dioxide into the atmosphere, and thus contributes to the Kyoto Accord to reduce the CO2 emissions.

The biomass used by Riso Scotti Energy is mainly derived from the waste from agricultural and food processes, such as rice husks, but also uses recovered wood, such as dead branches or industrial waste from the local wood and furniture sector.

The plant is capable of producing electrical energy with a maximum output of approximately 6MW.

It comprises the following subsystems: a fuel dosing and storage system; the steam generating boiler; exhaust gas treatment; a condensation steam turbine; the generator, transformer room and connection to the ENEL national grid; and a boiler water supply demineralisation system.

The biomass is introduced into the furnace and completely burned.

The furnace is fitted with a specially designed grate.

This ensures that the slag that is produced is kept to a minimum.

Also, the pollutant waste gases produced are minimised.

The heat from the combustion process turns the water in the boiler into steam.

This in turn is used to generate electrical energy in the turbine-generator system.

The generator output voltage is 6kV.

This is then converted to 15kV in the transformer room before its carefully controlled introduction to the national grid run by ENEL.

The whole energy producing plant is monitored and controlled from a central control room.

Three operators can view all areas of the plant using the visualisation capabilities offered by Cimplicity Plant Edition.

The operators sit at PCs, one of which is acting as the main server, the other two acting as viewers.

The PCs are connected via an Ethernet network to GE Fanuc PLCs which provide the local plant control.

Two Series 90-70 PLCs in a hot backup redundancy configuration provide the main communication between Cimplicity and the plant instrumentation.

Should there be a problem on one 90-70, the other 90-70 will take over its functions without interruption.

Six Series 90-30 PLCs, also on the network, are fitted with the latest CPU364s.

They provide local control of the grate, exhaust, boiler, water demineralisation, condenser/phosphates and the turbine.

Thanks to the remote connection capabilities of Cimplicity, the plant processes can also be viewed away from the control room via an ISDN linked telephone line.

Engineer Francescone, Managing Director of Riso Scotti Energy, said: "Thanks to GE Fanuc technology, our renewable and alternative-fuelled power plant is able to meet the energy requirements of approximately 2000-3000 families, while completely respecting the environment.

Since the GE Fanuc technology has been introduced the plant downtime has been greatly reduced, and all the necessary information supplied to us is available in real-time thanks to Cimplicity".

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