Evaluation of low grade heat transport in the process industry using absorption processes

This paper looks at a long distance heat transportation system based on an absorption process using a mixture of water and ammonia as a working fluid in order to use low grade heat available in the process industry. This paper aims at establishing the potential of using this method for economically transferring low grade heat from process industries to domestic heat sinks. To do so, the efficiency of transporting low grade heat sources identified in the process industries was examined. The economic distance was defined as the limit for economically transferring low grade heat from the source to the domestic heat sink. Based on a 10 year payback period, it was shown that heat could reach as far as 30–40 km for low grade heat sources at temperature as low as 80 °C. Finally, the economic distance was expressed as a function of the amount of fuel equivalent associated with low grade heat recovery savings and the economics of the transportation solution was discussed with regards to the expected changes of the heating and steel price over time.