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在换热器的冷端或者热端增设旁路,可以增加控制的自由度,有利于操作平稳。当换热器增设旁路时,换热器设计裕量的大小对于旁路控制的有效性十分重要。目前,做工艺设计时,通常根据设计经验而确定设计裕量的大小,使得换热器的面积裕量过大或设计裕量不足,难以满足控制的要求。本文提出了一种定量求解换热器设计裕量的方法,对比分析旁路设计时操作裕量、结垢裕量和控制裕量的大小,为旁路优化控制奠定基础。最后结合实例证明定量求解设计裕量是十分必要的,且设置旁路可以使换热器在保证操作平稳的同时总满足控制要求。对换热器设计裕量与旁路设计的分析为提高换热网络的控制效果,节能降耗奠定了基础。
By adding bypass at the cold end or hot end of the heat exchanger, the degree of freedom of control can be increased and the operation is stable. When the heat exchanger bypasses, the size of heat exchanger design margin is very important for the effectiveness of bypass control. At present, the process design, usually based on design experience to determine the design margin size, making the heat exchanger area margin is too large or insufficient design margin, it is difficult to meet the control requirements. In this paper, a method to quantitatively calculate the design margin of heat exchanger is proposed. The comparison of the operation margin, the scaling margin and the control margin in bypass design lays the foundation for the bypass optimization control. Finally, with examples, it is proved that it is necessary to quantitatively solve the design margin, and setting the bypass can make the heat exchanger always meet the control requirements while ensuring smooth operation. Analysis of design margin and bypass design of heat exchanger laid the foundation for improving the control effect of heat exchange network and saving energy and reducing consumption.