Our state of the art plant in Avonmouth uses a mix of pyrolysis, gasification and oxidisation to recover energy from waste that has to be incinerated compliantly in accordance with legislation. The gases we produce are formed by pyrolysis and gasification of the fuel which are then subject to high temperature oxidation to produce heat or other forms of usable energy. Step one is Pyrolysis, which is the thermal degradation of material by heat in the absence of oxygen to yield a high temperature pyrogas made up of low molecular weight hydrocarbon gases, similar to natural gas and a residue of ash and carbon char. This reaction normally occurs in the temperature range 400*C – 800*C.
Published data suggests that, typically, the gaseous products of pyrolysis contain very low quantities of dioxins and certain other contaminants compared with incineration, and it follows that the requirement for flue gas clean-up should accordingly be reduced. The second step in our process, Gasification, in this context, is the high temperature reaction of carbon with steam and air, or recycled exhaust gas, to produce water gas or producer gas, leaving a small quantity of largely inert residual ash. This reaction normally occurs at a temperature in the order of 1000*C.
Recombination of hydrocarbon gases to form soots, tars, and other contaminant oils can occur if the gaseous mixture is allowed to cool. All chemical species are held in equilibrium at a micro scale depending on their partial pressures. These partial pressures change markedly with temperature change allowing any hydrocarbon material that is not oxidised to recombine in the temperature range 450*C – 250*C, so reversing the process of pyrolysis. For this reason, in Clinipower’s plant, the gases produced by the process are kept above the recombination temperature.
High temperature oxidation of the small molecules of the hot gases produced by pyrolysis and gasification must be complete and carried out with the optimal quantity of oxygen. It is generally recognised that oxidation at a temperature of about 1200*C will ensure the destruction of any dioxins present in the gas stream. For a more detailed overview of our processes, we always encourage our customers to visit our plant, ask questions and really get into the detail of how their waste is treated and recovered. To boom a visit or to speak with one of our team about your waste and how your waste could be recovered into energy in our process please get in touch – Contact us link –