Development of efficiency-enhanced cogeneration system utilizing high-temperature exhaust-gas from a regenerative thermal oxidizer for waste volatile-organic-compound gases

We have developed a gas-turbine cogeneration system that makes effective use of the calorific value of the volatile organic compound (VOC) gases exhausted during production processes at a manufacturing plant. The system utilizes the high-temperature exhaust-gas from the regenerative thermal oxidizer (RTO) which is used for incinerating VOC gases. The high-temperature exhaust gas is employed to resuperheat the steam injected into the gasturbine. The steam-injection temperature raised in this way increases the heat input, resulting in the improved efficiency of the gas-turbine. Based on the actual operation of the system, we obtained the following results:
• Operation with the steam-injection temperature at 300 °C (45 °C resuperheated from 255 °C) increased the efficiency of the gasturbine by 0.7%.
• The system can enhance the efficiency by 1.3% when the steam-injection temperature is elevated to 340 °C (85 °C resuperheated). In this case, up to 6.6 million yen of the total energy cost and 400 tons of carbon dioxide (CO2) emissions can be reduced annually.
• A gas-turbine cogeneration and RTO system can reduce energy consumption by 23% and CO2 emission by 30.1% at the plant.