基于稳态能量平衡的支路平衡控制

A pass temperature balance control for fired heater based on steady state energy balance

为避免加热炉支路温度平衡控制时的动态耦合引起系统波动甚至不稳定,本文提出了一种基于稳态能量平衡的加热炉支路平衡控制方案,并进行了收敛性分析。根据稳态能量平衡计算出各支路需调整的流量,使各支路温度趋向一致。支路平衡控制采用长控制周期的稳态控制和区域控制。分析表明,所提出方案易于稳定,且接近稳态下的理想控制。另外,实现了支路温度均衡下加热炉进料总流量自动提降负荷控制。仿真和现场应用结果表明,控制方案合理,效果良好。

A pass balance control scheme to maintain the pass outlet temperature to be same for multi-pass fired heater is proposed and the convergence of the control scheme is analyzed. To avoid the dynamic coupling of different pass streams caused by frequently adjustment of pass flow, individual pass flowrate is calculated based on steady state energy balance to drive its outlet temperature arrive at a temperature target, and the control interval is chosen long enough to let the control effects of pass flow change reach steady state. A zone control method is adopted when all the outlet temperature approach to the neighborhood of temperature target. The convergence analysis shows that the proposed strategy is easy to be stabilized and it is behaved near ideal steady state control. To not disturb the pass temperature balance when the setpoint of total load is changed, a load distributed control is designed. Simulation and field implementation results show that the proposed control scheme is very effective and easy to implement.