Experimental Investigations On Resuse Of Heat Of Gas Condensation In Regeneration Heat Exchanger

With the growing world energy shortage and the worsening environmental pollution, energy saving and pollutant reduction have become a worldwide issue. In China, the industrial energy consumption whose effectiveness is of great importance to reducing the unit GDP energy consumptions accounts for a large proportion of its total energy consumption. There is a considerable amount of waste heat in the flue gas exhaust in many of China's large industrial furnaces, which contains large amounts of water vapor. If the flue gas exhaust temperature is reduced below water vapor condensing temperature, both the sensible heat of flue gas and the latent heat of the water vapor condensation can be recycled, as can greatly improve the efficiency of the heating furnace's fuel utility.Conventional technology of recovering flue gas condensation heat bases on water with low temperature to cool flue gas. Flue gas condensation heat exchanger involves complex anti-corrosion technologies and high manufacturing costs, which is difficult to exploit to the industrial furnaces without water heating requirements. The regenerative heat exchanger is adopted in this paper to recover flue gas condensation heat. This type of heat exchanger has high efficiency, small volume and low costs. Meanwhile, it has a wider versatility using flue gas to heat the combustion-supporting air.It's resulted after thermal equilibrium calculation that the condensation of the water vapor in the flue gas is likely to be achieved when the flue gas temperature at the inlet of heat exchanger is no higher than 373℃, with Jiangsu Pipeline natural gas as fuel. A set of regenerative furnace experiment apparatus is established in this paper. Experiments show that the exhaust gas temperature can be reduced to about 20℃and the condensation heat of the water vapor in the flue gas is recovered. In that case, the furnace thermal efficiency is greatly improved. The Thermal efficiency is more than 100% calculated by fuel net calorific value, with the top value up to 108%.The impact of the switch period on the regenerative heat exchanger is also analyzed. It shows the shorter the period, the smaller the temperature fluctuates of the preheating air and the flue gas, and the lower the flue gas temperature. Meanwhile, the whole thermal efficiency of the furnace reaches its maximum. However, given the operation life of valves, the switch period of the real equipment can be set around 40 ~ 60s to achieve the optimization of thermal efficiency and system reliability.