Study On Hydraulic Balance And Heat Transfer Deterioration In Electromagnetic Induction Boiler

Against the background of global warming,energy shortage and increasingly stringent environmental protection requirements,governments of all countries have successively issued energy conservation and emission reduction policies.In this context,the utilization rate of renewable energy power generation in the world has increased rapidly,but the new energy power generation has the disadvantages of being unregulated,unstable,and unable to store in large quantities.As a new type of heat source for electric heating,electromagnetic induction boiler is a new technology for heating,which is in line with the national industrial policy on the power demand side.It can absorb the electric energy generated by renewable energy in a timely manner,and also supplement the traditional centralized heating mode.It has important significance in peak shaving and valley filling of the power grid,energy conservation and emission reduction,and has broad d evelopment prospects.However,at present,electromagnetic induction heating boilers still have problems such as hydraulic imbalance and heat transfer deterioration,which seriously affect the economic and safe operation of electromagnetic boilers and cause large energy waste.In this thesis,a series of studies have been carried out on the hydraulic balance of the same and different heating pipe networks of the electromagnetic induction boiler with different structural forms under different main pipe flows by using theoretical calculation and numerical simulation methods.The deterioration of heat transfer in the electromagnetic induction heating boiler has been studied from the perspective of hydraulic imbalance,and the wall temperature distribution of the heating steel pipe has been mastered.The flow imbalance law of different pipe network structures and the minimum flow rate that causes the heat transfer deterioration of the electromagnetic boiler have been preliminarily mastered.The error between the numerical simulation results and the theoretical calculation value is less than 5%.We have established a hydraulic balance and other resistance calculation model based on Excel complex circuit,and used this model to carry out theoretical calculation on t he same and different pass structures of electromagnetic induction boiler under different spacing and different main pipe flow conditions,and simulated them with numerical simulation method.In the same pass Z-shaped structure,when the main pipe flow is constant,the branch pipe spacing has little impact on the flow deviation degree,while in the different pass U-shaped structure,the branch pipe spacing has a greater impact on the hydraulic imbalance degree.The larger the branch pipe spacing,the greater the flow deviation degree.When the branch pipe spacing is fixed,the main pipe flow has little influence on the flow deviation of each branch pipe in the same and different pass electromagnetic boiler structure.Only in the same pass Z-type structure,when the main pipe flow is greater,the flow deviation of the first and fifth branches is greater.In different electromagnetic boiler structures,the flow deviation degree under different main pipe flow is slightly greater than that in the same pass Z-type structure.In this thesis,the Hardy Cross ring pipe network method is used to calculate the hydraulic balance of the heating pipe network structure of the same and different routes respectively,and the numerical simulation method is used to carry out the simulation study.The overall flow deviation of the heating pipe network Z-type structure of the same route is smaller.No matter in the electromagnetic boiler structure or in the heating pipe network,the flow distribution law of the same pass Z-shaped structure is that the flow at the branch near the inlet end is the smallest,and increases towards the outlet end in turn,while the flow distribution law in the different pass U-shaped structure is the opposite.According to the operating parameters and structural data of the electromagnetic induction boiler,we have carried out theoretical calculation and simulation analysis on the wall temperature of the heating steel pipe.To ensure the economic and safe operation of the electromagnetic induction heating boiler,the flow of the main pipe shall not be less than 2.58 t/h.In order to avoid the heat transfer deterioration of the electromagnetic induction heating boiler,the flow of the main pipe inlet shall not be less than 2.05 t/h.The above research can be used for reference in studying the hydraulic balance of pipe network and the design and operation of high-power multi-branch electromagnetic induction boiler.