Study On The Technology Of Circulatory Geothermal Energy Ice Period Water Delivery

Ensuring the groundwater balance And analyzing the characteristics of water transport in the glacial period of small and medium-sized channels in the plain area,this paper proposes a method of irrigation,drainage and circulatory geothermal energy for water transport in the glacial period.Firstly it is a idea that the channel low-temperature water is recharged to the aquifer by recharge well,and then in order to raise the channel water temperature and ensure that the groundwater balance and the channel has no ice cover or basically no ice cover water,the same amount of groundwater is injected and mixed with in channel which is drawn from the pumping well synchronously.Finally,the non-freezing length which is the length of glacial water transport by circulatory shallow geothermal energy is calculated in the heat balance theory of water body.This study provides a new idea for water transport in the glacial period in north area,especially in northern China and it will have positive significance for improving the efficiency of water transport in winter and reducing ice accidents.The factors of the environmental temperature,the spacing and arrangement of pumping wells,the channel water temperature(before recharge),the recharge water temperature,the recharge amount,the hydrogeological parameters,the skeletal thermophysical parameters and the channel infiltration have influence on aquifer temperature field changes,pumping well temperature,pumping volume and unfrozen length of open channels by the model which the well pattern was simulated by simultaneous irrigation and pumping.At the same time,the analysis of the economic cost of geothermal energy utilization provides a scientific basis for engineering operation and design.It is shown that the cold environment affects the efficiency of channel water delivery and even causes ice accidents in the study.However,during the glacial period,the recharge water temperature has little effect on the outlet water temperature of the pumping well.Therefore,the influence of ambient temperature on the outlet water temperature of the pumping well can be neglected.Compared with other well layout methods,horizontal countercurrent well layout is the best way to avoid the occurrence of heat breakthrough.In order to ensure the rational utilization of the geothermal field,the pumping and irrigation quantity must be considered in combination with the well spacing.When the pumping and irrigation quantity increases,the spacing of the pumping wells also needs to be increased.The thickness of the aquifer,permeability and porosity,longitudinal dispersion coefficient and other parameters have obvious influence on the temperature field which are important stratum parameters to be considered when using geothermal energy to transfer water in glacial period.The other parameters have relatively little influence on the temperature field.The thickness of aquifer,permeability coefficient and porosity,thermal transverse dispersion coefficient are proportional to the final pumping temperature.The underground water thermal conductivity,soil skeleton thermal conductivity and thermal longitudinal dispersion coefficient are inversely proportional to the final pumping temperature.The influence depth of channel infiltration water temperature in this study is less than 10 m,which cannot reach the depth of aquifer.Therefore,it can be determined that channel infiltration has little effect on aquifer temperature field and pumping temperature.Through the research,the ice-age water conveyance technology of recycling geothermal energy has been formed.The calculated water conveyance capacity has increased by more than 20% compared with the traditional ice-age water conveyance,and the ice jam accident rate of ice-age water conveyance has decreased by more than 90%.Taking Jiaolai water conveyance canal section as an example,the synchronous pumping and irrigation mode is adopted in every kilometer of water conveyance canal section to carry out water conveyance in glacial period,which saves at least 1 million yuan of electricity consumption per year compared with the traditional ice-age water conveyance method.More importantly,ice-free water conveyance can increase the flow of water conveyance(which can be increased by 30% in actual measurement),reduce investment(insulation board,ice sluice,etc.),ice damage and loss caused by ice damage.Based on the pumping and irrigating well pattern,the role of well group model in the circulatory shallow geothermal energy during glacial water transport is further studied.This study makes up for the relatively small amount of pumping water in the well mode and increases the distance of the non-freezing length.As for the water transmission channels,due to the large span of the region,the hydrogeological conditions along the main channel vary,and there are often some areas along the channel rich in groundwater resources and geothermal energy.Some areas along the route are short of groundwater and geothermal energy resources.There are many natural conditions that limit the total ice-free flow of water from the entire main line.Therefore,the study of well group model is very important.The study shows that,under the condition of the same amount of pumping and irrigation,the most advantageous mode of synchronous pumping and irrigation well group to the recycling utilization of shallow geothermal energy during glacial water transport is the one-to-one countercurrent form of pumping and irrigation Wells.The key point is to design the different well spacing and the same well spacing.In order to increase the non-freezing length of water transport in the glacial period,it is a reasonable plan to use the method of one-to-one countercurrent to arrange pumping and irrigation Wells in the area with abundant groundwater resources.Through the comprehensive analysis of many factors,the suitable spacing of similar Wells is determined.When the pumping water demand increases,the number of pumping Wells can be increased one by one perpendicular to the direction of groundwater flow.Based on the thermodynamic equilibrium theory of water body,the open-channel water-pumping and ice-melting model is established to analyze the influence of ice condition,channel geometry section,channel bed ground temperature,solar radiation,air temperature convection,evaporation,water kinetic energy and other factors on water transport during the glacial period.At the same time,the heat balance components are calculated and the unfrozen length of the water delivery channel in winter is obtained.On this basis,the calculation method of subsection unfrozen length is proposed,and the unfrozen length of the final water temperature and the remaining total heat reserves of each subsection channel under the final subsection channel can be calculated.