Municipal Solid Waste and Bio-Solids Gasification

 

 A schematic depicting the process unit components of a system to convert bio-solids (sewage sludge) and municipal solid waste or light construction and demolition waste as shown below. Overall the average fuel calorific value of the fuel mix must be approximately 6,500 BTU/lb or higher and the average moisture content must be below approximately 40%.


These fuel characteristics can be achieved by partial drying of the sludge and by addition of high BTU fuels such as construction and demolition waste, landfill gas, shale gas, shredded tires or coal. In the schematic below, municipal solid waste is the main fuel, the sludge is pre-dried to a solids content of at least 25% and landfill gas provides the additional calorific value, when needed, needed to bring the feed average to greater than 6,500 BTU/lb.

A fuel gas containing approximately 50% methane is often available from gas wells in landfills. High BTU value shale gas is also available in areas where shale gas bearing formations are accessible. Other sources of high BTU waste or such as tires or plastic waste can also be used to enhance average fuel BTU value.

Synthesis gas produced in the gasifier is used to fire a steam boiler, which, in turn drives a steam turbine generator. The flue gas from the boiler is clean enough to release in most areas. However, EPR deploys a full gas clean up train to insure that regulated emissions are far below applicable standards and in many cases undetectable.

The solid residual slag produced by the process is completely inert and can be used for aggregate or construction fill.  This slag ordinarily comprises approximately 4% to 5% of the waste entering the gasifier by weight.

EPR stand s ready to carry out site surveys with prospective clients to determine what potential waste fuels are available and how they might be combined to economically convert problem wastes such as bio-solids to clean, renewable energy.