Abstract: In the original design of the waste heat boiler of tail gas incinerator in the high sour natural gas purification units in Puguang Gas Field, high sulfur content (about 400-800 mg/m³) of the flue gas after combustion leads to high acid dew point temperature of flue gas, so the designed flue gas temperature of waste heat boiler is high, resulting in low thermal efficiency (only about 62-70%) of the entire waste heat boiler. However, the sulfur content of the flue gas during actual operation of the incinerator is about 150-370 mg/m³, so the actual acid dew point temperature is below 185℃. Therefore, an algorithm is proposed to dynamically predict the acid dew point temperature of flue gas according to the sulfur content of flue gas, and a thermal analysis platform is established for incinerators and waste heat boilers. Since the heat absorption of the superheater of waste heat boiler in the special water-side process of "two intakes and one outtakes" is far greater than that of evaporator and economizer, the idea that "the steam quality can be ensured only by simultaneously installing superheater and economizer " is proposed. The transformation scheme of dynamically reducing the flue gas temperature under different working conditions is given, which can control the reasonable flue gas temperature in real time to prevent acid dew point corrosion, maximize the recovery of heat energy of the flue gas from incinerator, and realize an annual gas saving of 3.69% while ensuring the production and quality of superheated steam.

Key words: purification unit, tail gas incineration, waste heat boiler, energy saving