Improvement Of Cathodic Protection Of Greenhouse Buried Heat-supply Pipeline Based On Thermoelectric Generation

With the global economy progresses and people's living standards continue to increase,the demand for traditional energy sources continues to increase,leading to serious energy shortages and environmental problems.New energy power generation technology has become a key research project in the world.Among them,the research hotspot of thermoelectric power generation technology in China is usually the use of waste heat and waste heat in industrial production and vehicle driving.The greenhouse is a typical waste heat resource,and the application of this technology in greenhouses is of great research value.In order to grow off-season plants and southern plants,the northern greenhouses usually use hot water pipes to heat the greenhouse.Cathodic protection is an important technology to ensure the operation of underground metal pipes in greenhouses.In order to reduce the corrosion rate of heating pipes,in the buried arrangement of metal pipes,cathodic protection technology is usually used in combination with the outer anti-corrosion layer.This is the most economical and reasonable anti-corrosion measure.However,the conventional external current cathodic protection method is costly and large in area.The cathodic protection life of the sacrificial anode method is too short and the anode needs to be replaced frequently.In order to solve this problem,this paper analyzes the thermoelectric effect and the principle of thermoelectric power generation on the basis of reviewing the literature and understanding the research situation at home and abroad,especially the P-V characteristics of the thermoelectric battery are analyzed.In this paper,the surface temperature of the greenhouse heating pipe is used as the hot end of the temperature difference battery.The heat sink is buried in the soil to dissipate heat for the cold end of the temperature difference battery,and the residual heat in the greenhouse heating process is energy converted by the Seebeck effect.The selected greenhouse heating pipeline heat source was subjected to field test research.Combined with the heat transfer theory,measures to reduce thermal resistance were added to the utilization of heat sources.According to the PV characteristics of the temperature difference battery and the results measured in the heat source test,the overall design of the temperature difference cathodic protection system was carried out.The circuit was designed and simulated by TINA,and the BQ25504 chip was connected at the output end of the temperature difference battery to collect the maximum power point tracking mode.The temperature difference energy is then supplied by the buck regulator chip LM317.Finally,the device was used in the greenhouse to conduct cathodic protection of the underground buried heating pipes in the external current mode,and the pipeline protection effect under different protection voltages was studied.Through experiments,it is found that the temperature difference between the greenhouse heating pipeline and the surrounding soil is large enough to be used as a heat source for thermoelectric power generation.The simulation analysis results show that the output voltage of the temperature difference cathodic protection device designed in this paper can meet the actual cathodic protection requirements of pipelines.In the field test,hot water was used as the heat source of the temperature difference battery.Under the cooperation of the multimeter and the saturated copper sulfate reference electrode,the protection potential of the pipeline after connecting the device was measured,which proved that the device designed in this paper can really play a role.Provides cathodic protection of external current mode for greenhouse heating metal pipes.The device uses the temperature of the buried metal pipe in the greenhouse as a heat source during operation,and has the advantages of almost no land occupation,long-term use,flexible protection mode,energy conservation and the like.This study provides a more feasible solution for the protection of greenhouse heating pipelines,and also preliminary exploration of short-distance pipeline protection technology with external current mode.