Application Of Active Condensation Systems For Utilizing The Higher Heating Value Of Fuels

Abstract

Aiming for a more energy-efficient use of energy also requires utilizing a higher heating value (HHV) of fuel. In systems where consumers of thermal energy with a temperature lower than ~50 °C are present, HHV is used directly by flue gas condensers or water spray exchangers. HHV is directly used in vapour pump boilers. In conditions without low-temperature consumers, it is necessary to raise the heat of vapour condensation in the flue gas to the consumer's temperature. This case occurs in almost every domestic district heating system, the industry of alcoholic and non-alcoholic beverages, and milk and milk product industries. In these cases, the heat of vapour condensation is raised using the absorption and compressor heat pumps. These described configurations are recognized in the literature as active condensation systems. The most common systems among them are a) systems in which the heat pump takes heat from the return flow from the consumer and releases it to the return downstream of the flue gas condenser, b) systems with a wet heat exchanger in which the condensed and filtered vapour is passed through the heat pump evaporator directly or via a heat exchanger. Latter systems are mostly researched with biomass combustion because they allow using HHV of fuel and lower particle emissions in flue gas simultaneously, while the former systems are most often used in district heating. High temperature, compression, absorption and hybrid heat pumps enable the use of condensation heat at temperatures higher than 100 °C.