Energy - Ecological Recovery System from Waste Gas

Actually, the high amounts of thermal energy, called waste energy, having the low level of temperature and pressure, resulting from various technological plants are evacuated in the environment. From the chemical analysis of the waste fluids, we observe that the thermal potential is important and some components, having especially the gaseous phase, may produce an important pollution effect on the surroundings. Frequently we find in the waste gas the pollutant components as CO, CO2, NOx, SO2 and different vapours (water, organic components), which impact negatively the environment. It is well known that the liquid pollutant phase may be easier treated than the gaseous phase. Unfortunately the important amount of waste energy, resulted from the burning plants, is evacuated in the gas phase and an ecological treatment of that is difficult to be realised efficiently. This paper proposes a combined recovery system of the thermal energy and of a fraction of vapour pollutant components from the waste gas, in aim to reduce the thermal and chemical pollution. The system consists in an initial compression of gas. Consequently, the dew point temperature rises and the vapour latent heat utilisation at an acceptable mean level of temperature is realisable. This process is followed by the separation of liquid phase and the dry gas is expanded in a turbine or is driven to an absorption/adsorption reactor. The expansion allows the use of the gas, having a low temperature, in a refrigeration or in conditioning systems. Due of the acceptable temperature of liquid phase, having a high pressure, a secondary heat recovery is recommended. By applying this treatment of the waste gas the minimisation of waste fluids injected into the atmosphere may be reached. On the other hand, a deep recovery of heat is realised and the increase of the overall efficiency of principal plant too. The proposed system described in this paper is accompanied by the typical examples. The range of characteristic parameters is outlined.