Energy recycling of pyrolysis water as a part of coal‐water fuel

Abstract

Under research, there is a combustion process of multicomponent coal-water fuel (CWF) that was conducted with mixing ratio of coal, pyrolysis, and technical water. The pyrolysis water was extracted through pyrolysis oil settling, where the oil was obtained from pyrolysis of wood waste. Ignition and combustion of CWF samples were carried out in a combustion chamber at heating medium temperatures (Tg = 600-1000°C, with an interim step of 50°C). Gas-phase combustion products were analyzed with a flow-line gas analyzer. Technical water in CWF composition was replaced with pyrolysis one that was acted to raise the reactive capacity. It resulted in reducing the ignition delay time τi (by an average of 25%) and the minimum ignition temperature (from 440°С to 393°С, reliance on a CWF composition). In addition, increase in flame combustion time was recorded by an average of 20%, as well as dependence on a heating medium temperature and a CWF composition. In the case when a CWF liquid-phase component was completely replaced with the pyrolysis water, the significant increase in heat value by 2.14 MJ/kg was observed. According to the data of the flow-line gas analyzer, we concluded that the CWF combustion based on the pyrolysis water was accompanied by less NOx emission (by an average of 22%) but more CO and CO2 amount (by an average of 1.4 and 1.2, respectively). It was found according to the results of the energy balance assessment that application of pyrolysis water in CWF composition leads to a decrease in fuel consumption for heat production by 16.7%.