Heat exchange network pinch point determining method based on nonlinear temperature-enthalpy relation of each fluid
A heat exchange network and determination method technology, which is applied in the determination field of process industry heat exchange network, can solve problems such as inability to design correctly, and achieve the effect of being easy to promote and use
Inactive Publication Date: 2012-08-15
ZHEJIANG UNIV OF TECH
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[0004] In order to overcome the shortcomings of existing heat exchange network determination methods that cannot correctly design critical fluids or near-critical fluids, phase change fluids, etc., which have significant changes in specific heat capacity, that is, heat exchange networks with nonlinear temperature-enthalpy relations, the present invention provides a method that can A Pinch Point Determination Method for Heat Exchange Network Based on the Nonlinear Temperature-Enthalpy Relationship of Each Fluid Considering the Influence of Fluid Nonlinear Temperature-Enthalpy Relationship
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[0032] The present invention will be further described below in conjunction with the accompanying drawings.
[0033] refer to Figure 1 to Figure 7 , a pinch determination method for a heat exchange network of a fluid with a nonlinear temperature-enthalpy relationship, comprising the following steps:
[0034] 1) Input the physical parameters of the stream that need heat exchange in the industrial process: the initial temperature of the fluid, the target temperature, the amount of heat exchange, the characteristics of the relationship between temperature and enthalpy, the specific heat capacity, and the flow rate.
[0035] 2) Draw the temperature change and enthalpy change curves of all fluids on the temperature-enthalpy diagram.
[0036] First, the fluid temperature is converted to a displacement temperature, that is, the temperature of the hot stream is reduced by ΔT min / 2, the temperature of the cold stream increases by ΔT min / 2:
[0037] T ...
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The invention discloses a heat exchange network pinch point determining method based on the nonlinear temperature-enthalpy relation of each fluid. The method comprises the following steps of: (1) drawing a temperature change-enthalpy change relation curve of each fluid on a temperature-enthalpy graph; (2) establishing a continuous cold / hot fluid temperature-enthalpy relation curve; (3) determining the pinch point temperature and the minimum utility energy value; and (4) determining a heat exchange network with the maximum heat recycle amount: according to the continuous cold / hot fluid temperature-enthalpy relation curve obtained in the step (3) which indicates the change condition of the energy of each fluid along with temperature in the heat exchange process, drawing a vertical line on each connection point of the temperature-enthalpy curve, and obtaining a heat exchange network with the maximum heat recycle amount directly by use of the structure chart of the heat exchange network. The invention provides a heat exchange network pinch point determining method, which can take the influence of the fluid nonlinear temperature-enthalpy relation into consideration and is based on the nonlinear temperature-enthalpy relation of each fluid.
Description
technical field [0001] The invention relates to a method for determining heat exchange networks in process industries, in particular to a method for determining pinch points in heat exchange networks for fluids with nonlinear temperature-enthalpy relationship. Background technique [0002] In the process industry, some streams need to be heated while others need to be cooled. By reasonably matching these streams for heat exchange, making full use of the heat of the stream itself, using the hot stream to heat the cold stream, or the cold stream to cool the hot stream, so that the stream reaches the specified temperature and phase state, and recovers heat through the system To reduce the consumption of external utilities, this is the task of the heat exchange network. The heat exchange network is used to recover the energy available in the system and reduce the demand for external public works. It is an important subsystem of process industries such as chemical industry, meta...
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IPC IPC(8): G05D23/00
Inventor 蒋宁华丽云
Owner ZHEJIANG UNIV OF TECH