Technology Research Of Energy Saving And Optimization Control On Mine Direct Coal Flow Conveyor System

As a transportation equipment of bulk material,the belt conveyor has the advantages of high operation efficiency,numerous transportation materials,long transportation distance and low maintenance cost.It is widely used in the fields of mine,pier,oil and other fields.In the processes of coal transportation,the operation power consumption of the belt conveyor is generally high,and it has two main reasons.On the one hand,the belt conveyor runs at the high speed.The amount of coal on the conveyor belt is generally less than the standard value of the original design,and sometimes the belt conveyor even runs with no load.On the other hand,multi-level belt conveyors are generally started according to the direction of the reverse coal flow.Only after all levels of belt conveyors are in turn started and run stably,the coal is transported on the conveyor belt.These two aspects greatly increase the light-load or no-load running time of the belt conveyor,resulting in unnecessary mechanical wears,wasting a lot of power.Therefore,it is imperative to study the technology of energy saving and optimization control on mine direct coal flow conveyor system.In order to achieve the requirements of the energy saving on the coal flow conveyor system,the researches are done from three aspects in this paper.Firstly,through the optimization matching between belt speed and material flow,the energy-saving technology of speed control for the belt conveyor is proposed,and the goal is achieved that “more coal faster pull,less coal slowly pull”.Secondly,based on speed control,the start delay time of all levels of belt conveyors are in turn calculated,and the energy-saving technology of the start along the coal flow is proposed,which shortens the no-load running time of belt conveyors.Thirdly,through integrating the first two energy-saving technologies,the energy-saving optimizationexperiment with the transient speed-up time control for the belt conveyor is carried out.According to the premise that the material cross-sectional area on the conveyor belt can be maximized through reducing appropriately the belt speed,the energy-saving technology of speed control for the belt conveyor is proposed.The principle of the energy-saving technology and the blanking forms the belt conveyor in the coal mine are analyzed.In view of the discontinuity of the coal production,the motors driving belt conveyors often run on the non-optimal operation point,and the speed of the belt conveyor can not be adjusted frequently.So a ladder matching model between belt speed and material flow is built.At the transient speed-up process of the belt conveyor,reasonable speed and acceleration curves are designed,and the calculation method of the minimum speed-up time is obtained.Based on the previous study of the start method along the coal flow for multi-level belt conveyors,the energy-saving technology of the start along the coal flow based on speed control is proposed.By comparing various speed and acceleration curves,the expression of the “S” soft start speed curve is designed.In order to greatly realize the start processes along the coal flow for multi-level belt conveyors,the corresponding process fault protection measures are taken.Combining with the data in the actual coal transportation site,simulation analyses of the energy-saving technology of the start along the coal flow based on speed control are carried out.That is establishing the specific ladder matching model between belt speed and material flow,solving the acceleration and minimum speed-up time in the transient speed-up process,and imitating the processes of the start along the coal flow and the speed-up for four-level belt conveyors.From two aspects that the power consumption and the no-load running time,the energy-saving calculation analyses are done.The results show that the energy-saving efficiency is 6.2%,and the saving no-load running time in one day is 0.97 h.In view of the energy-saving technology of speed control for the belt conveyor and the start along the coal flow based on speed control for multi-level belt conveyors,the speed-up process is involved for the belt conveyor in short period of time.Therefore,the energy-saving optimization experiment with the transient speed-up time control for the belt conveyor is designed,including the selection of hardware,the design of the electrical schematic,the installations of the hardware equipment,the preparations of the PLC program and the drawings of the touch screen.On the basis of the speed detection and control experiment of the belt conveyor,the energy-saving optimization experiment with the transient speed-up time control is carried out.Through the experiment test and energy-saving analyses,the experiment results show that the minimum speed-up time,which is calculated according to the acceleration designed in the transient speed-up process,meets the experiment requirements,and is beneficial to the energy saving and reducing unnecessary mechanical losses.