ANALYSIS OF THE PROCESS OF WATER VAPOR CONDENSATION WITHIN GAS ATMOSPHERES AND COMBUSTION PRODUCTS

Abstract

Water vapor is the most important working medium by the processes of energy generation and conversion. The H2O content in gases and gas mixtures serves as a standard of their desiccation by technological processes. The presence of vapor in the air-oxidizer provides a reduction of harmful substances formation by combustion. The values characterizing the saturation state: the dew point tdew and the wet bulb thermometer twb temperature are used to evaluate an approximation degree of the wet gas system (any air, gas mixtures or combustion products) to the condensation state. The values of these parameters have been determined for moist air in dependence on the basic temperature and the relative humidity of an air. The lower are the temperature values tdew, twb, the wider is the region of H2O existence in the vapor phase. The EUROSTAT’s gas fuels list includes the natural gas (NG), blast furnace gas (BFG), coke oven gas (COG). Calculations of dew point values of the combustion products for the gas fuels: NG, COG, BFG has been carried out in dependence on the characteristics of the combustion air: the oxidizer excess factor l, the temperature ta and the relative humidity ja. The dew point tdew values have been found under standard conditions for the combustion products of the listed gas fuels, presented by stoichiometric (l = 1.0) mixtures with dry air: pure methane, NG, COG, BFG. The tdew values make — respectively 59.3; 58.5; 11.1; 61.5. In the case of saturated air as an oxidizer at temperature of 25 °C, the dew point for the combustion products of the listed fuels makes the folloving values: 62.0; 61.5; 25.6; 64.0 °C respectively. The fractions of H2O in the vapor and liquid phases of natural gas combustion products are determined as a function of temperature by condition that the 100 % content of H2O in from of vapor state (without water) corresponds to the saturation temperature (or dew point).This temperature has value of about 60°C for combustion products under stoichiometric air/gas ratio. Bibl. 31, Fig. 10, Tab. 3.