关键词: 换热器, 状态空间模型, 数据校正, Kalman滤波

Abstract: In a refinery accurately extracting data of heat exchanger network has intimate influences on schemes of heat integration and performances of optimal operation. For data reconciliation of nonlinear state parameters of a heat exchanger, a lumped parameter heat transfer model, which features partitioning the heat exchanger with piecewise linear sub-models, was proposed to overcome the difficulty of nonlinear state space equations induced by nonlinear change of stream properties in the heat exchanger. A set of state space equations on the basis of piecewise linear Kalman filtering was established. A method of data reconciliation for nonlinear state parameters of heat exchangers was proposed. The procedure of the proposed approach and its behaviors were exemplified by data reconciliation for a high pressure heat exchanger in a wax oil hydrotreating unit. The results show that the convergence of the proposed model is strongly dependent upon numbers of partitioning segments for a heat exchanger. The state parameters of heat exchanger tend to be convergent to a constant as the numbers of partitioning segments increase. And numbers of partitioning segments should be determined by trial-and-error according to requirements of computational precise in practice. When the inlet temperatures of heat exchanger are measured, the outlet temperatures can be rectified using the proposed method. And data reconciliation on the inlet and outlet temperatures of the heat exchanger can be performed iteratively. The proposed method can be effectively used for data reconciliation of nonlinear state parameters of heat exchangers. The proposed approach has higher accuracy for data reconciliation of larger difference between inlet and outlet temperatures or dramatic changes of physical properties of streams in heat exchangers.

Key words: heat exchanger, state space model, data reconciliation, Kalman filtering