How can waste-to-energy plants be made safer?

Waste-to-energy units convert household waste into energy. They are environmentally friendly and specially designed to comply with European standards for gas emissions or noise pollution. In addition, the water used in the plant is always in a continuous circuit: in other words, it is never discharged.

These units treat the household waste of about 1 million people. Some of this waste is transformed into energy and the rest is recycled into road surfaces, for example. They can produce more than 200 million kWh, which represents the average consumption of more than 50,000 households per year.

Difficult valves to operate

The principle of energy recovery is to produce electricity from the steam produced by the combustion of waste using a furnace/boiler system.

The steps of this complicated and sensitive process are separated by valves from the reception of household waste to its burial. These valves are sometimes very often used and sometimes not enough. Two problems can arise from these manipulations:

• - Hardware problems for valves that are never used: they break and too often have to be replaced.
• - Health problems for operators who continuously operate the valves

Modec has worked with the major players in waste-to-energy conversion to find solutions to these two valve actuation problems:

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• Maintain valves with low pressure to avoid breakage
• Facilitate the operation of the valves for operators and thus protect their integrity.

Maintain valves with low pressure to avoid breakage 

Careful maintenance of the valves of waste-to-energy plants prevents serious accidents such as leachate leaks[residual liquid that results from the percolation of water through a material]. A 30 m³ leachate leak can lead to the contamination of more than 2 tonnes of soil!

These leaks occur especially when valves that are rarely used are opened with force and break the system around the valve, causing cracks. These errors can be easily avoided with simple measurements and efficient equipment :

• update of the technical instruction relating to the management of the valves in the retention area ;
• daily check of the state of the valves in the retention area added to the checklist of daily checks to be carried out on the leachate treatment unit ;
• reminder given to all staff at the operations meeting on the role and management of the retention area valves throughout the site.

Modec intervened during the implementation of the daily control of the proper functioning of the valves. Thanks to our portable valve handling devices, this control becomes easy, fast, safe and effortless for the operator. The valves open and close in one of 30 seconds, the control time is divided by three!

Make it easier for operators to operate the valves

There can be several dozen valves per waste-to-energy unit, and many of them are manually operated several times a day by on-site operators for production purposes. These operators do not operate these valves for their sole activity. This is why this task had to be automated. Fixed valve actuators were not a solution because they were too expensive compared to the number of valves on site. That's why the portable valve actuator, easy to transport, easy to supply, without risk of sparks, is the best solution.