ENERGY-CONSERVATION VIA OPTIMAL-CONTROL OF CONE CRUSHERS

The quarrying industry has a major impact on the environment. The impa ct arises from direct sources (that is the quarrying operation with at tendant noise and dust) and indirect sources (that is electricity usag e). To quantify these usages, the quarrying industry in the United Kin gdom consumes some 4.8 TW h/year, representing 3 per cent of installed generating capacity. A significant proportion of this usage is attrib utable to machines known as cone crushers. Cone crushers are large ite ms of plant (up to 3 m diameter) producing, mainly, aggregates for the road-making industry. The British output is currently 230M tonnes per annum, due to rise to 400M tonnes by 2011. The energy costs are curre ntly 240M Pounds per annum. Further environmental issues are raised by the use of manganese steels. A crusher uses components that can wear away at a rate of 1 mm per hour. If the parts are not renewed at regul ar intervals machine performance can be dramatically affected and, in the worst case, mechanical damage may occur. The parts are replaced ea rly to avoid damage with a concomitant poor energy utilization. The pa per describes a programme of work intended to address some of these pr oblems. Pegson Limited, a leading manufacturer of crushing plant, in a ssociation with Transfer Technology plc and De Montfort University, ar e co-operating in a project funded by SERC/DTI under the design of hig h-speed machinery LINK programme. Treatment is theoretical, demonstrat ing the justification of the funding. A follow-up paper will detail ac tual savings and contrast them with the theoretical model. The next ge neration of crushers will be instrumented with a range of sensors to m onitor machine performance. Of especial interest is a novel sensor whi ch monitors the wear of the crushing components. The sensors are conne cted to a knowledge-based system (KBS) to monitor and control performa nce. The sensors are not reported in any detail due to the pursuance o f Intellectual Property Rights. The ideal performance parameters are o btained from another KBS based on rock mechanics and models of wear me chanisms. The advanced crushers incorporate a simple man/machine inter face and make much use of distributed control based on NEC 78K series microcontrollers. Preliminary studies indicate that energy savings of 15M Pounds in the United Kingdom (over 400M Pounds worldwide) per year are realizable. Further savings of 5M Pounds in the United Kingdom (n early 150M Pounds worldwide) per year arise from the optimal use of th e manganese crushing components.