Research On Comprehensive Energy-Saving Of Circulating Cooling Water System

The circulating cooling water system(CCWS)is a common industrial auxiliary cooling system and is widely used in the industrial field.The system is used to eliminate waste heat generated in industrial production processes,and plays an important role in ensuring product quality and maintaining production safety.CCWS is a water-saving unit in the industrial process,which can greatly save industrial water,but the system is also a high-energy consuming unit in the process.Moreover,due to the lack of energy-saving awareness and rough production management,the energy-saving state of the system is often not ideal,and the system has great energy-saving potential.With the emphasis on energy-saving technologies and applications in the whole society in recent years,researches on energy-saving related to CCWSs have made a lot of progress,but there are still some shortcomings and gaps in many aspects.In summary,this thesis takes the industrial CCWS as the main research object,the operation process and operation mechanism of each sub-system and the whole system are deeply analyzed,and the existing energy saving research results are researched and improved.Finally,the comprehensive energy-saving research of CCWS was performed,including comprehensive system modeling,operation optimization,comprehensive evaluation,energy-saving bottleneck diagnosis,and energy-saving retrofit.The main work of this thesis includes:1.System integrated modeling.System integrated model can provide a complete mathematical description of the system operation mechanism,which is the basis for the related energy-saving research of this system,and it is also an important tool for system simulation and performance analysis.Therefore,this thesis proposes a function unit division method for mechanism analysis,and builds a hierarchical superstructure integrated model of CCWS.The model can integrate the mechanism model of operating equipment,and describe the key information such as equipment type,topology structure and equipment operating state.The system model has been expanded.Furthermore,this model describes the system mechanism more comprehensively and deeply,takes into account the model versatility,and is easy to program.2.Operation optimization.Through the coordination of all system operating equipments,the operation optimization research can improve the energy-saving level of the existing CCWS,and makes the system reach the optimal energy-saving operation state.In this thesis,the system operation optimization research based on superstructure modeling is performed,and the optimization model is extended to realize the simultaneously optimization of operating equipments.Moreover,by integrating the network hydraulic balance,operation experience and other domain knowledge,the operation optimization model and algorithm are improved,the optimization effect and operation efficiency are improved,and the optimal operation scheme is obtained.3.Comprehensive evaluation.The comprehensive energy-saving evaluation can objectively and comprehensively reflect the energy-saving state of CCWS,and is the basis of energy-saving research.Based on the analysis of system energy flow and material flow,this thesis establishes a set of new comprehensive evaluation indexes for CCWS,which can describe the system energy saving level from many aspects.Furthermore,in order to combine subjective expert experience knowledge and objective data information,this thesis designs a combined weighting method based on analytic hierarchy process method and entropy weight method to achieve comprehensive energy-saving evaluation.4.Energy-saving retrofit based on bottleneck diagnosis.Energy-saving evaluation can analyze the energy-saving level of the system,but it cannot improve the energy-saving level of the system.Furthermore,the energy-saving retrofit study of industrial systems can maximize the use of existing resources,improves the energy-saving level of existing systems,and reduces the investment and the impact on the environment in new projects.In order to obtain the best energy-saving effect,it is necessary to perform a targeted energy-saving retrofit according to the energy-saving bottleneck in the system.Therefore,this thesis proposes an energy-saving bottleneck diagnosis method based on multi-mode energy efficiency density decomposition and orthogonal test analysis,and then quantifies the retrofit value of each sub-system.Based on this,the optimization design of the retrofit schemes is performed,and the evaluation of these schemes is performed in combination with the knowledge of the post-project evaluation.The energy-saving effect is analyzed and a large amount of decision-making information is provided.5.Energy-saving analysis and retrofit.Industrial systems are complex and diverse,and there may be cases where the model has low accuracy or a faint mechanism.Therefore,for the research on energy-saving retrofit of CCWS,this paper also proposes a data-driven method to adapt to different energy-saving retrofit application environments.This method uses the idea of analytic hierarchy process to improve the data envelopment analysis method,comprehensively analyzes multiple input and output indicators,and comprehensively solves many problems such as system energy-saving state evaluation,energy-saving weak link analysis,and retrofit scheme design.The above researches aimed at the key scientific and common technical problems in the energy-saving research of CCWS,and a comprehensive energy-saving research is performed integrating modeling,optimization,evaluation,analysis and retrofit.In the research process,based on the CCWS data,the above proposed methods are simulated.The simulation results verify that the research can save the energy and resource consumption of the CCWS,reduces the operation cost,and improves the enterprise's revenue.This research can improve the energy-saving level and automation level of CCWS,and it has important practical significance and theoretical value.