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Belting the worlds' longest single flight conventional overland belt conveyor
Abstract
Wesfarmers North Curragh mine, Australia and design and construction contractors, Laing'Rourke, undertook a joint project, to develop the latest CV1103 belt conveyor system. The new belt conveyor system incorporates a number of innovative energy saving features, such as intelligent, multi-speed VF drives, low rolling resistance pulley cover rubber, large idler rolls, and wide idler spacing. The belt conveyor also includes high efficiency chute designs, along with a significant variable geometry design at the mid station drive, minimizing dust and belt wear. Some of the significant design and selection procedures involved in developing the belt conveyor, include significantly low rolling resistance pulley cover and better crack and aging resistance factors. The latest belt conveyor has been able to generate significant cost benefits, such as 41% operating cost and 39% capital cost.
... The theoretical analysis along with experimental validation on a VSD based conveying system is presented in [14]. Nowadays, the idea of speed control has been adopted by industry and successfully applied to some practical projects [14,15,17,18]. Further investigations on VSDs of belt conveyors are carried out in [13]. ...
a b s t r a c t The improvement of the energy efficiency of belt conveyor systems can be achieved at equipment and operation levels. Specifically, variable speed control, an equipment level intervention, is recommended to improve operation efficiency of belt conveyors. However, the current implementations mostly focus on lower level control loops without operational considerations at the system level. This paper intends to take a model based optimization approach to improve the efficiency of belt conveyors at the opera-tional level. An analytical energy model, originating from ISO 5048, is firstly proposed, which lumps all the parameters into four coefficients. Subsequently, both an off-line and an on-line parameter estimation schemes are applied to identify the new energy model, respectively. Simulation results are presented for the estimates of the four coefficients. Finally, optimization is done to achieve the best operation efficiency of belt conveyors under various constraints. Six optimization problems of a typical belt conveyor system are formulated, respectively, with solutions in simulation for a case study.
... The load dependent control strategy is also applied to a passenger conveyor for energy optimization in [18]. Nowadays, the idea of speed control has been adopted by industry and successfully applied to some practical projects [15,16,19,20]. The current strategy of speed control employs lower level control loops or multi-speed drive to improve the operation efficiency of an individual belt conveyor [16,17]. ...
The improvement of the energy efficiency of belt conveyor systems can be achieved at equipment or operation levels. Switching control and variable speed control are proposed in literature to improve energy efficiency of belt conveyors. The current implementations mostly focus on lower level control loops or an individual belt conveyor without operational considerations at the system level. In this paper, an optimal switching control and a variable speed drive (VSD) based optimal control are proposed to improve the energy efficiency of belt conveyor systems at the operational level, where time-of-use (TOU) tariff, ramp rate of belt speed and other system constraints are considered. A coal conveying system in a coal-fired power plant is taken as a case study, where great saving of energy cost is achieved by the two optimal control strategies. Moreover, considerable energy saving resulting from VSD based optimal control is also proved by the case study.
New developments in the pipe conveyor and belt are advanced to address the growth in the capacity, length and complexity of pipe conveyor systems. Improved belt construction can offer better stability during horizontal curves and resistance to twist. Low rolling resistance rubber compound can significantly lower the power consumption and belt tension, producing capital and operation cost savings. Dynamic analysis, when used to analyze the conveyor’s starting and stopping behavior, can improve the design and reliability of long overland pipe conveyor systems. For these three aspects, technical backgrounds and field installations as examples are discussed in this paper.
Open loop optimal control approach has been applied to operation efficiency of belt conveyors in our previous works. When applied to field conveyor systems, its optimal instructions may result in constraint violations because an open loop mechanism cannot deal with the disturbances from the coal consumption forecasting and the feed rate. In this paper, a closed-loop model predictive control (MPC) approach is proposed aiming at the above problem. A coal feeding process, containing 6 belt conveyors, in a coal-fired power plant is taken as a case study. The open loop control and the closed-loop MPC are both formulated for comparative study. The disturbance of coal consumption rate forecasting and the disturbance of feed rate are further imposed on the two approaches, respectively. The results show that both the two control approaches, with energy cost as their objective function, are capable to achieve energy cost optimal operation of belt conveyors. Furthermore, the closed-loop MPC approach excels the open loop optimal control in dealing with disturbances. Unlike open loop optimal control, MPC approach can get feasible solutions against the above disturbances by compensating them with its closed-loop control mechanism.
In literature, variable speed control of belt conveyors is recommended to save energy consumption. However, the current implementations mostly focus on lower level control loops without operational considerations at the system level. This paper intends to take a model based optimization approach to improve the operation efficiency of belt conveyors with consideration of various constraints. Specifically, three optimization problems of a typical belt conveyor system are formulated, respectively, with solutions in simulation for a case study. I. INTRODUCTION
The energy efficiency of belt conveyor systems can be improved at equipment or operational levels. In literature, variable speed control is proposed as an effective way to improve operation efficiency of belt conveyors. However, the current strategies most focus on lower control loops without considerations at the system level. In this paper, an optimal scheduling is proposed to improve the energy efficiency of belt conveyor systems at the operational level, where time-of-use (TOU) tariff, ramp rate of belt speed and other system constraints are considered. A coal conveying system in a coal-fired power plant is taken as a case study, where great savings of both energy cost and energy consumption through the optimal scheduling are achieved.
Variable speed control is proposed in literature to improve the operation efficiency of a belt conveyor. However, the current implementations mostly focus on lower level control loops without considerations at the system level. This paper intends to introduce optimisation approach to improve the operation efficiency of the belt conveyor under various constraints. An open loop optimal control is firstly proposed and followed by a closed-loop model predictive control (MPC). A typical belt conveyor is taken as a case study where the open loop and closed-loop control strategies are simulated, respectively. The simulation results are presented to show the advantages of the optimisation of operation efficiency of belt conveyors. Further, the rustiness of the MPC approach under certain disturbance is also convinced by the case study.
Determining the coefficient of resistance f for the calculation of the main resistance of belt conveyors is more a matter of experience than of calculation. DIN 22101 provides indications for the estimation of the coefficient of resistance. Although there are no clear directives, the standard provides a rough classification into four groups. This is not surprising as these directives are mainly based on experiences from practice and are hardly or not at all supported by theoretical and experimental scientific research. During these last fifty years research on this subject has been performed by various European institutions. The theoretical research dealt mainly with the indentation resistance and the resistance of the bearings of the rolls, and sometimes with the flexure resistance of the belt. The experimental research was mainly concerned with the measuring of the main resistance. The result of the measurement was then recorded in mathematical terms and the separate components were distinguished from the main resistance by tricks. This research strongly advanced the insight into the physical phenomenon. So far, however, a complete model for the calculation of the main resistance on the basis of the physical properties of the belt and bulk material and the geometry of the belt conveyor, has not yet been published. In 1978 and 1979 reports were published on the results of research performed by the Laboratory of Transport Technology of the Delft University of Technology on the indentation resistance [17] and flexure resistance [18] of belt conveyors. The physical model of the indentation resistance and the flexure resistance was caught up by Gladysiewicz [4] and Jonkers [5] and amplified with considerations on the properties of rubber. The research performed by the Delft University of Technology is reported here. The following physical models are described in turn: the indentation resistance of the belt; the flexure resistance of the belt; and the flexure resistance of the bulk material flow. From these models a programme is deduced for the calculation of the main resistance. Finally, the model is verified on the basis of a number of measurements of the main resistance obtained by Limberg [5].
The 20 km Channar overland belt conveyor system in Western Australia set new standards for low rolling resistance. The conveyor circuit consists of one 10.3 km overland with a 9 km horizontal curve radius extending over a 4 km arc, as presented in Fig. 1, and one 10.1 km straight overland conveyor. Extensive testing was allowed during commissioning to verify many design aspects of interest. Extremely low power consumption was measured. A DIN friction factor f = 0.0098 [6] was recorded on the straight conveyor, and f = 0.0110 on the horizontally curved conveyor. These values challenged the basis of the existing standards which govern the design criteria of modern conveyors. This paper presents the argument for change, from present standards ([4], [5], [6]) to a power equation based on viscoelastic and viscoplastic theory for systems where the difference has a significant impact on the capital and operating costs. The paper further compares the calculated results of dynamic tuning with field measurements, and of other points of interest implemented in the Channar design.
The power of rubber is commanding special respect for its importance to belt conveyor design and performance. Cover rubber rolling resistance, energy consumption theory, laboratory investigation and field measurement validation surveys are presented in Part I. This shows new procedures to test rubber specimens and rationalize differences among polymers to meet different environmental applications with important cost benefits. Conveyor performance can now be predicted accurately! In Part II of this two part series, splice core rubber compatibility and its dynamic endurance to fatigue will take on new definition through a presentation of new testing procedures. These procedures quantify differences in the polymer physical properties among manufacturers that can improve their competitive edge, and extend their range of performance to higher belt strengths. This paper extends information on Conveyor Dynamics, Inc. (CDI) prior work [1] and [2], providing new findings, methods and recommendations that significantly alter transportation economics of overland and pipe conveyors through the understanding of their rubber systems. Fig. 1 is a photograph of the 5 km German Creek curved overland conveyor (Australia), jointly engineered with Barclay Mowlem Construction Limited. Barclay Mowlem received an Engineering Excellence Award in 1996 from The Institution of Engineers, Australia for their achievements on this modern installation. This paper discusses some of the new technologies applied in the engineering of this overland belt conveyor.
The physical properties of conveyor belt cover pates manufactured from rubber influence the level of the conveying systems' energy consumption. The dynamic modulus and the phase lag angle are rubber parameters whose size and temperature dependence can themselves be influenced by varying the compounding and processing parameters. The idea is to develop conveyor belts with cover plates with a reduced energy consumption reflecting a reduced indentation rolling resistance. To this end, the motion resistances caused by the belt are measured, initially, conveyor belt cover plates with different rubber compounds are tested on a temperature controllable revolution test rig to determine their energy consumption. This gave important information for the optimization of the compounding. The next step involved selecting and, in some cases, modifying different cover plates. The test conditions were varied within ranges reflecting actual conveyor belt operating conditions. The results revealed wide differences in energy consumption for belts with the same construction but different cover plate compoundings, such as those used in open cast lignite mines in the Rhine area. In the case of steel cord belts, it was shown that those belts with lower nominal belt rating over the whole analysed temperature spectrum also had lower indentation rolling resistance. Cross reinforcing on the steel cord belt bottom side had a beneficial effect. Information on the compounding was obtained which will help reduce the indentation rolling resistance and thus the overall energy consumption. Currently, there are no known dynamic parameters which allow the precise calculation of conveyor belt energy consumption. Not even a suitably adapted test method for small conveyor belt samples can replace the measurement of the indentation rolling resistance on a revolving belt.