Analysis of the use of waste heat obtained from coal-fired units in Organic Rankine Cycles and for brown coal drying

The ever-increasing restrictions on greenhouse gas emissions have created a need for new energy technologies. One way to meet these new requirements is to optimise the efficiency of power units. This paper presents two energy technologies that, if used, will increase the efficiency of electricity generation. One of the most effective ways to improve the efficiency of brown coal-fired units is by drying the coal that is fed into the boiler. Here, we describe a technology that uses the waste heat obtained from exhaust gases. This paper also presents an analysis of the feasibility of and potential for using waste heat obtained from exhaust gases to feed Organic Rankine Cycles (ORCs). Several low-temperature working fluids were considered, which were selected based on properties that were best suited for these types of cycles. The impact of these working fluids on the efficiency and capacity of the ORC was also examined. The calculations for ORCs fed with waste heat obtained from exhaust gases from hard coal- and brown coal-fired boilers were compared.

► We describe a technology that uses the waste heat obtained from exhaust gases.
► The impact of using different working fluids with a low boiling point is examined.
► We describe integrating the ORC with the power unit.
► The use of waste heat from boiler exhaust gases to dry brown coal is proposed.
► We demonstrate a possible increase in power unit efficiency.