Heat Recovery Boiler’s Reformation Of 1.4 Million Tons/year Catalytic Cracking Unit

The model of waste heat boiler of petrochemical refinery catalytic cracking unit in Ji Lin is Q203/530-7.8/88-3.92/440, it built and put into operation in 2002. It mainly used surplus heat in high-temperature regenerative flus gas (temperature 530 ℃, flow 202800Nm3 /h) produced in apparatus production process to produce medium-pressure superheated steam, needed for the production process and supply of power plant. The medium-pressure productive stream system are composed of the heat recovery boiler and external catalyst cooler of catalytic cracking unit, in addition to its own production for medium-pressure steam (Slurry evaporator produces low-pressure steam), but offering external catalyst cooler and oil slurry evaporator hot water at the same time, and overheating the saturated steam produced by the heat exchanger with the same parameter.In this paper, a detailed analysis is made on the problem of excessive discharge of flue gas of the waste heat boiler of catalytic cracking unit, the selection of flue gas denitrification process and system optimization of the waste heat boiler is completed, the related indexes and parameters were established, through the technical transformation of boiler pipe coefficient, the efficiency of the waste heat boiler flue gas denitrification can be kept in an average of more than 85%, denitrification system is designed according to the efficiency of 80%, the power plant in accordance with the efficiency of 65% to carry out in daily operation, indicating that the existing system has good stability, and achieve the standard of flue gas emission。In view of the high energy consumption of the waste heat boiler of catalytic cracking unit, the problem of high energy consumption is analyzed in detail. Through the waste heat boiler superheater, economizer device transformation, after the transformation catalytic cracking unit energy consumption than the transformation of the former operation energy consumption reduced about 49.21kg standard oil/tons of raw materials.