| Because of the energy condition of the wealth of coal and poverty of oil and gas in China,coal has been playing an important role in energy field for a long period of time.Preliminary forecasted,there will be about 4 billion tons of coal produced from underground,and 80%of them will be used for power generation and heating by 2015.But with the underground coal massively produced from underground,a large area of the subsidence surface in goaf formed,and it would have an influence on buildings on the ground and seriously damage the ecology.Castoff such as fly ash,which was produced by power plant burnt from coal produced from underground,is used up much of our land.Therefore,it brings a lot of economic and social problems from output to industrial use of the coal.Backfill mining technology can effectively solve the surface subsidence in goaf and make full use of power plant waste,and it combines the social benefit with the economic benefit.Therefore,the research of fly ash pneumatic convey technology in goaf will have a far-reaching impact on the development and progress of green mining system in our country.Pneumatic stowing is an application of pneumatic conveying technology in mining industry.Airflow with some kinetic energy is used for stowing power,and with water through the pipeline it will be condensed into a certain supporting strength of powder solid materials which will be delivered to fill the goaf.This paper focuses on the positive pressure conepump pneumatic conveying system for observation and experiment,using fly ash as the transmission medium,and it analyzes the related rules in the conveying process.The main results were shown as follows:1.The stress condition of solid particles in the pneumatic conveying and basic flow was introduced,and analyzed the characteristics of group flow in the experiment which was the main object of the study;2.The common parameters of pneumatic conveying,was calculated and analyzed to find the inherent law;3.Researched on the pneumatic experiment conveying system and optimal designed the system;4.With the fly ash as conveying material,through the analysis of experiment three factors on the transport length,gas flow rate and conveying pressure,it researched the related influencing factors on pneumatic conveying experimental system,and it also observed and analyzed the changes rules of pressure,flow with time in the conveying process to find out the optimal parameters and system configuration in the experiment;5.Flow state was measured and monitored by Electrical Capacitance Tomography(ECT)through the whole experimental process,and the system internal flow pattern and concentration distribution of gas-solid two-phase flow was researched by analysis of self-recording real-time image,and it verified the conclusion of the experiment as well.In summary,this paper analyzed and researched through the theory analysis and experiment of related parameters in the fly ash pneumatic conveying the process of to find out the basic conveying rules of gas-solid two-phase flow in the the pneumatic conveying process,and it also calculated and determined the optimal parameters and system configuration in the experiment in order to reach the purpose of improvement conveying efficiency and reducing energy waste. |
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