CN-121980718-A - Method and system for converting multistage superstructure by heat exchange network flow chart

CN121980718ACN 121980718 ACN121980718 ACN 121980718ACN-121980718-A

Abstract

The invention discloses a method and a system for converting a multi-stage superstructure by a heat exchange network flow chart, belonging to the technical field of petrochemical industry in the process industry. The method ensures that the process of converting the multi-stage superstructure by the heat exchange network flow chart is strictly based on actual process logistics logic by determining the initial cold logistics stage and the initial hot logistics stage of each heat exchanger, then divides the heat exchange network flow chart into an upper region and a lower region of the pinch point by using a key boundary line in the thermodynamics of the pinch point, further respectively updates the initial cold logistics stage and the initial hot logistics stage of the heat exchanger in each region, accurately and effectively constructs a cold logistics final stage and a hot logistics final stage for solving the multi-stage superstructure, and ensures that the generated multi-stage superstructure has the minimum stage number by calculating the superstructure parameters and the total superstructure stage number, thereby furthest reducing redundant variables and constraints of the multi-stage superstructure and improving the conversion efficiency and the solving efficiency of the multi-stage superstructure.

Inventors

XIE YANLI
CAI YUTIAN
SUN XI
YE JIANYUN
XU ZUWEI
ZHANG BINGJIAN
CHEN QINGLIN
ZHAO KAI

Assignees

中石化节能技术服务有限公司
中山大学

Dates

Publication Date: 20260505
Application Date: 20251231

Claims (10)

1. A method for converting a multi-stage superstructure by a heat exchange network flow chart, comprising: Acquiring a heat exchange network flow chart, determining an initial cold logistics level and an initial hot logistics level of each heat exchanger based on logistics temperature data of each heat exchanger in the heat exchange network flow chart, and dividing the heat exchange network flow chart into an area above a pinch point and an area below the pinch point; Updating an initial cold stream level and an initial hot stream level of each heat exchanger in the area above the pinch point, determining a cold stream final level and a hot stream final level of each heat exchanger in the area above the pinch point, and further determining a super-structure parameter of the area above the pinch point; Updating the initial cold stream stage and the initial hot stream stage of each of the heat exchangers in the region below the pinch point to determine the cold stream final stage and the hot stream final stage of each of the heat exchangers in the region below the pinch point; determining the super-structure parameters of the area below the pinch point and the total super-structure number of the multi-stage super-structure based on the cold material flow final stage and the hot material flow final stage of the heat exchanger; And based on the cold flow final stage and the hot flow final stage of each heat exchanger, combining the super-structure parameters of the region below the pinch point, the super-structure parameters of the region above the pinch point and the super-structure total number of stages of the multi-stage super-structure, and converting the heat exchange network flow chart into the multi-stage super-structure.
2. The method of claim 1, wherein the step of obtaining a heat exchange network flow chart, determining an initial cold flow level and an initial hot flow level for each heat exchanger based on flow temperature data for each heat exchanger in the heat exchange network flow chart, and dividing the heat exchange network flow chart into an upper region of a pinch point and a lower region of the pinch point comprises: acquiring a heat exchange network flow chart, and determining stream temperature data of each heat exchanger in the heat exchange network flow chart, wherein the stream temperature data comprises a hot stream inlet temperature and a cold stream inlet temperature of each heat exchanger; Determining the heat exchange sequence of each heat exchanger in the hot stream based on the hot stream inlet temperature of each heat exchanger; Determining the heat exchange sequence of each heat exchanger in the cold stream based on the cold stream inlet temperature of each heat exchanger; determining an initial hot stream stage of each heat exchanger based on the heat exchange sequence of each heat exchanger in the hot stream; determining an initial cold stream stage of each heat exchanger based on a heat exchange sequence of each heat exchanger in the cold stream; Dividing the heat exchange network flow chart into an upper region and a lower region of the pinch point, wherein the upper region of the pinch point comprises an upper non-pinch point region and an upper pinch point region of the pinch point, and the lower region of the pinch point comprises a lower non-pinch point region and a lower pinch point region of the pinch point.
3. A method of converting a multi-stage superstructure according to claim 1, wherein said updating the initial cold and hot stream stages of each of said heat exchangers in the region above said pinch to determine the final cold and hot stream stages of each of said heat exchangers in the region above said pinch to determine the superstructure parameters of the region above said pinch comprises: the region above the pinch point comprises a non-pinch point region above the pinch point and a pinch point region above the pinch point; Screening a plurality of first heat exchangers in a non-pinch area above the pinch, and determining a cold stream final stage and a hot stream final stage of each first heat exchanger in the non-pinch area above the pinch based on an initial cold stream stage and an initial hot stream stage of each first heat exchanger; Screening a plurality of third heat exchangers positioned in a pinch point area above the pinch point, and determining a cold stream diversion result and a hot stream diversion result of each third heat exchanger; updating the initial cold stream stage and the initial hot stream stage of each third heat exchanger based on the cold stream split result and the hot stream split result of each third heat exchanger, and determining a cold stream final stage and a hot stream final stage of each third heat exchanger in a pinch region above the pinch; -taking the cold and hot final stages of each of said first heat exchangers and the cold and hot final stages of each of said third heat exchangers as the cold and hot final stages of each of said heat exchangers in the region above said pinch; Based on the cold and hot final stages of the flow of each of the heat exchangers in the region above the pinch, a superstructure parameter of the region above the pinch is determined in combination with the flow temperature data of each of the heat exchangers in the region above the pinch.
4. A method of converting a multi-stage superstructure in a heat exchange network flow scheme as claimed in claim 3 wherein said screening a plurality of first heat exchangers in a non-pinch region above said pinch, determining a cold stream final stage and a hot stream final stage for each of said first heat exchangers in a non-pinch region above said pinch based on an initial cold stream stage and an initial hot stream stage for each of said first heat exchangers, comprises: Screening a plurality of first heat exchangers located in a non-pinch region above the pinch based on cold stream inlet temperature data of each heat exchanger, and determining a plurality of first cold streams located in a non-pinch region above the pinch based on the first heat exchangers; Marking the first heat exchangers on each first cold stream based on a preset stream direction, and determining an initial updated heat exchanger of each first cold stream; Iteratively updating the initial cold stream stage and the initial hot stream stage of each first heat exchanger on the basis of the initial update heat exchanger of each first cold stream until each first heat exchanger on each first cold stream determines a respective cold stream final stage and hot stream final stage; The method comprises the steps of screening a plurality of second heat exchangers which need to be updated on a first cold stream of each first cold stream in each first cold stream, comparing initial cold stream levels and initial hot stream levels of the initial heat exchangers, updating the initial cold stream levels of the initial heat exchangers if the initial hot stream levels of the initial heat exchangers are larger than or equal to the initial cold stream levels, further determining a cold stream final level and a hot stream final level of the initial heat exchangers, updating the initial cold stream levels and the initial hot stream levels of each second heat exchanger, taking the next second heat exchanger of the initial heat exchangers as the initial heat exchanger to be updated next after the second heat exchangers are updated, determining the initial cold stream final level and the initial hot stream final level of the initial heat exchangers based on the initial cold stream levels and the initial hot stream levels of the initial heat exchangers if the initial hot stream levels of the initial heat exchangers are smaller than the initial cold stream levels of the initial heat exchangers, and taking the next initial heat exchangers as the initial heat exchangers.
5. The method of converting a heat exchange network flow chart into a multi-stage superstructure according to claim 3, wherein said screening a plurality of third heat exchangers located in a pinch region above said pinch and determining cold and hot flow split results for each of said third heat exchangers, updating an initial cold and hot flow stage for each of said third heat exchangers based on the cold and hot flow split results for each of said third heat exchangers, and determining a cold and hot flow final stage for each of said third heat exchangers located in a pinch region above said pinch, comprises: Screening a plurality of third heat exchangers positioned in a pinch point area above the pinch point, and determining a cold stream diversion result and a hot stream diversion result of each third heat exchanger, wherein the cold stream diversion result comprises a diversion cold stream and a non-diversion cold stream; if the cold stream of the third heat exchanger is a non-split cold stream and the hot stream of the third heat exchanger is a split hot stream, determining a plurality of first tributary heat exchangers corresponding to the third heat exchanger based on the split hot stream of the third heat exchanger; if the cold stream of the third heat exchanger is a split-stream cold stream and the hot stream of the third heat exchanger is a non-split-stream hot stream, determining a plurality of second tributary heat exchangers corresponding to the third heat exchanger based on the split-stream cold stream of the third heat exchanger; and updating the initial hot stream stage of the second tributary heat exchanger based on the initial cold stream stage of the second tributary heat exchanger, determining the stream end shared stage of the third heat exchanger, and determining the hot stream final stage and the cold stream final stage of the third heat exchanger based on the stream end shared stage.
6. A method of converting a multi-stage superstructure in a heat exchange network flow chart according to claim 3, wherein said updating of initial cold and hot stream stages for each of said heat exchangers in said region below said pinch to determine cold and hot stream final stages for each of said heat exchangers in said region below said pinch comprises: the region under the pinch point comprises a non-pinch point region under the pinch point and a pinch point region under the pinch point; Screening a plurality of fourth heat exchangers positioned in a pinch point area below the pinch point, and determining a cold stream diversion result and a hot stream diversion result of each fourth heat exchanger; determining a cold stream final stage and a hot stream final stage of each of the fourth heat exchangers in a pinch region below the pinch based on the cold stream split result and the hot stream split result of each of the fourth heat exchangers; And determining the cold stream final stage and the hot stream final stage of each fifth heat exchanger in the non-pinch region below the pinch based on the fourth heat exchanger by combining the cold stream type and the hot stream type of each fifth heat exchanger.
7. The method of converting a heat exchange network flow chart into a multi-stage superstructure according to claim 6, wherein said screening a plurality of fourth heat exchangers located in a pinch region below said pinch and determining a cold flow split and a hot flow split for each of said fourth heat exchangers, and determining a cold flow final stage and a hot flow final stage for each of said fourth heat exchangers located in a pinch region below said pinch based on the cold flow split and the hot flow split for each of said fourth heat exchangers, comprises: Screening a plurality of fourth heat exchangers in a pinch region below the pinch, and determining a cold stream diversion result and a hot stream diversion result of each fourth heat exchanger, wherein the cold stream diversion result comprises a diversion cold stream and a non-diversion cold stream; Based on the prepositive cold stream side heat exchanger and the prepositive hot stream side heat exchanger, updating the initial cold stream level and the initial hot stream level of each fourth heat exchanger, and determining the first cold stream level and the first hot stream level of each fourth heat exchanger; comparing the sizes of the first cold stream stage and the first hot stream stage of the fourth heat exchanger if the cold stream of the fourth heat exchanger is a non-split cold stream and the hot stream of the fourth heat exchanger is a non-split hot stream, determining a cold stream final stage and a hot stream final stage of the fourth heat exchanger based on the comparison result, and updating the first cold stream stages of the rest fourth heat exchangers on the cold stream of the fourth heat exchanger or the first hot stream stages of the rest fourth heat exchangers on the hot stream of the fourth heat exchanger based on the cold stream final stage and the hot stream final stage of the fourth heat exchanger; If the cold stream of the fourth heat exchanger is a non-split cold stream and the hot stream of the fourth heat exchanger is a split hot stream, determining a plurality of third branch heat exchangers corresponding to the fourth heat exchanger based on the split hot stream of the fourth heat exchanger, determining a cold stream side maximum stage corresponding to the fourth heat exchanger based on the initial cold stream stage of the third branch heat exchanger, and determining a cold stream final stage and a hot stream final stage of the fourth heat exchanger based on the cold stream side maximum stage and the first hot stream stage corresponding to the fourth heat exchanger; Determining a cold stream side maximum stage corresponding to the fourth heat exchanger based on an initial hot stream stage of the fourth tributary heat exchanger, and determining a cold stream final stage and a hot stream final stage of the fourth heat exchanger based on the cold stream side maximum stage and the first cold stream stage corresponding to the fourth heat exchanger; And determining a cold material flow side maximum stage and a hot material flow side maximum stage of the fourth heat exchanger based on the initial cold material flow stage of the fifth branch heat exchanger, and further determining a cold material flow final stage and a hot material flow final stage of the fourth heat exchanger based on the cold material flow side maximum stage and the hot material flow side maximum stage of the fourth heat exchanger.
8. The method for converting a heat exchange network flow chart into a multi-stage superstructure according to claim 7, wherein said screening a plurality of fifth heat exchangers in a non-pinch region below said pinch and determining a cold stream type and a hot stream type for each of said fifth heat exchangers, determining a cold stream final stage and a hot stream final stage for each of said fifth heat exchangers in a non-pinch region below said pinch based on said fourth heat exchangers in combination with the cold stream type and the hot stream type for each of said fifth heat exchangers, comprises: Screening a plurality of fifth heat exchangers in a non-pinch area below the pinch, and determining the cold stream type and the hot stream type of each fifth heat exchanger; If the cold material flow type of the fifth heat exchanger is a preset third cold material flow type or a preset fourth cold material flow type, determining a fourth heat exchanger corresponding to the fifth heat exchanger based on the cold material flow of the fifth heat exchanger, and determining the number of non-split heat exchangers between the fifth heat exchanger and the corresponding fourth heat exchanger on the cold material flow of the fifth heat exchanger; If the heat flow type of the fifth heat exchanger is a preset third heat flow type or a preset fourth heat flow type, determining a fourth heat exchanger corresponding to the fifth heat exchanger based on the heat flow of the fifth heat exchanger, and determining the number of non-split heat exchangers between the fifth heat exchanger and the corresponding fourth heat exchanger on the heat flow of the fifth heat exchanger; and if the cold material flow type of the fifth heat exchanger is a preset fifth cold material flow type or the hot material flow type is a preset fifth hot material flow type, comparing the initial cold material flow level and the initial hot material flow level of the fifth heat exchanger, and determining the hot material flow final level and the cold material flow final level of the fifth heat exchanger based on a comparison result.
9. The method for converting a multi-stage superstructure in a heat exchange network flow scheme of claim 7, wherein said determining the superstructure parameters and the overall number of superstructure stages of the multi-stage superstructure based on the cold and hot stream final stages of said heat exchanger comprises: Determining a virtual heat exchanger hot stream stage based on the heat capacity flow rate of each of the hot streams in the heat exchange network flow diagram; performing blank level parameter filling on each cold stream based on the cold stream final level of each heat exchanger on each cold stream; performing blank level parameter filling on the heat exchanger at the leftmost side on each cold stream based on the cold stream final level of the heat exchanger at the leftmost side on each cold stream; Filling blank-stage parameters of each hot stream based on the final stage of the cold stream of each heat exchanger on each hot stream; performing blank level parameter filling on the heat exchanger at the leftmost side on each hot stream based on the hot stream final level of the heat exchanger at the leftmost side on each hot stream; determining a super-structure parameter of the region below the pinch point based on the blank level parameter; acquiring the quantity of cold public works of the heat exchange network flow chart, and determining the type of the super-structure total number of stages judgment problem based on the quantity of the cold public works, wherein the type of the super-structure total number of stages judgment problem comprises a pinch point problem and a threshold value problem; If the type of the problem is the pinch point problem, re-filling blank level parameters of the hot material flow and the cold material flow to re-determine the super-structure parameters of the area below the pinch point, and further determining the super-structure total level of the multi-level super-structure based on the maximum value of the final level of the hot material flow of the heat exchanger; and if the type of the problem is a threshold value problem, determining the total number of the super-structure of the multi-level super-structure based on the maximum value of the final level of the heat flow of the heat exchanger.
10. The system for converting the multi-stage superstructure by using the heat exchange network flow chart is characterized by comprising a heat exchanger initial stage determining module, a regional logistics final stage determining module above a clamping point, a regional logistics final stage determining module below the clamping point, a superstructure parameter determining module and a multi-stage superstructure converting module; The heat exchanger initial stage determining module is used for acquiring a heat exchange network flow chart, determining an initial cold material flow stage and an initial hot material flow stage of each heat exchanger based on material flow temperature data of each heat exchanger in the heat exchange network flow chart, and dividing the heat exchange network flow chart into an area above a pinch point and an area below the pinch point; The above-pinch region logistics final stage determining module is used for updating an initial cold logistics stage and an initial hot logistics stage of each heat exchanger in the above-pinch region, determining a cold logistics final stage and a hot logistics final stage of each heat exchanger in the above-pinch region, and further determining the super-structure parameters of the above-pinch region; the final stage determining module of the area flow under the pinch point is used for updating the initial cold flow stage and the initial hot flow stage of each heat exchanger in the area under the pinch point and determining the final stage of the cold flow and the final stage of the hot flow of each heat exchanger in the area under the pinch point; the super-structure parameter determining module is used for determining super-structure parameters of the area below the pinch point and the total super-structure number of the multi-stage super-structure based on the cold material flow final stage and the hot material flow final stage of the heat exchanger; The multi-stage superstructure conversion module is used for converting the heat exchange network flow chart into a multi-stage superstructure based on the cold flow final stage and the hot flow final stage of each heat exchanger by combining the superstructure parameters of the region below the pinch point, the superstructure parameters of the region above the pinch point and the superstructure total number of stages of the multi-stage superstructure.

Description

Method and system for converting multistage superstructure by heat exchange network flow chart Technical Field The invention belongs to the technical field of petrochemical industry, and particularly relates to a method and a system for converting a multi-stage superstructure by using a heat exchange network flow chart. Background In the field of petrochemical industry, the design and optimization of a heat exchange network (Heat Exchanger Network, HEN) are key links for improving energy utilization efficiency and reducing production cost. The heat exchange network flow chart is taken as a tool for intuitively expressing the heat exchange relationship between the process streams, and intuitively shows the matching relationship between the cold stream and the hot stream, various related distribution setting data of the heat exchanger and the split situation of the process streams. The Multi-stage super-structure topology (Multi-stage Superstructure Topology) discretizes the whole heat exchange process into a plurality of continuous stages, and performs synchronous optimization in a framework covering all potential stream matching and arrangement possibilities through a mathematical programming (such as MINLP and NLP) method. The multistage superstructure topology can systematically and comprehensively cover possible logistics combinations and heat exchange sequences in a Heat Exchange Network (HEN), effectively ensures that potential excellent schemes are not missed in the optimization solving process, and is widely applied to the comprehensive and reconstruction optimization problems of the heat exchange network. In practical industrial application, as the number of process streams increases, the model scale increases exponentially, resulting in a drastic increase in solution complexity and severely limiting the application of the superstructure model in the industrial field. The existing method is low in efficiency and easy to make mistakes, and is difficult to process a logistics structure comprising complex split flow, mixed flow and crossing pinch points, or a simple sequential mapping rule is adopted, so that the converted topological structure cannot be strictly equivalent to the heat exchange logic of the original flow chart, a large number of redundant variables and constraints can be introduced, the difficulty of solving the multi-stage superstructure is obviously increased, and even a feasible solution cannot be obtained due to the expansion of the problem scale. Disclosure of Invention The invention aims to provide a method and a system for converting a multi-stage superstructure by a heat exchange network flow chart, which are used for solving the technical problems, an initial cold material flow stage and an initial hot material flow stage are constructed by material flow temperature data, and a cold material flow final stage and a hot material flow final stage are calculated by dividing the regions above a clamping point and the regions below the clamping point, so that superstructure parameters and a superstructure total stage number are constructed, the multi-stage superstructure of the heat exchange network flow chart is converted, and the accuracy and the efficiency of converting the multi-stage superstructure of the heat exchange network flow chart are improved. In order to solve the technical problems, the embodiment of the invention provides a method for converting a multi-stage superstructure by a heat exchange network flow chart, which comprises the steps of obtaining the heat exchange network flow chart, determining an initial cold flow grade and an initial hot flow grade of each heat exchanger based on the logistics temperature data of each heat exchanger in the heat exchange network flow chart, dividing the heat exchange network flow chart into an upper-clamping-point area and a lower-clamping-point area, updating the initial cold flow grade and the initial hot flow grade of each heat exchanger in the upper-clamping-point area, determining the final cold flow grade and the final hot flow grade of each heat exchanger in the upper-clamping-point area, further determining the superstructure parameters of the upper-clamping-point area, updating the initial cold flow grade and the initial hot flow grade of each heat exchanger in the lower-clamping-point area, determining the final cold flow grade and the final heat grade of each heat exchanger in the heat exchanger based on the upper-clamping-point area, determining the super-structural superstructure parameters of each heat exchanger in the upper-clamping-point area and the super-structural superstructure based on the total-structural parameters of the heat exchanger and the super-structural heat exchanger. It can be understood that compared with the prior art, the method and the device for converting the multi-stage super-structure through the heat exchange network flow chart determine the initial cold logistics stage and the initial