Cement, Energy and Environment July-Sep 2002

• MPC is predictive; an expert system is algebraic • MPC is closed- loop control ; an expert system is open-loop control. • MPC is a lgorithm-based an expert system is ru les-based. • MPC accepts setpoints for controlled variables; an expert system only accepts ranges for the controlled variabl es. • MPC includes dynamics; an expert system does not. • MPC is robust, whi ch means inaccurate models have litt le impact on performance. This last featu re - robustness - is important because it means that process drift has li ttle impact on closed-loop performance. There are many MPC applications that litera lly have been on-lin e continuously for I0 years without re-tuning. There is one advantage that an expert system has, however. An expert system can be made fast under upset condit ions, in that a large move can be put out to the process immediately. This is very impottant for major upsets such as a kiln '"ri ng" or "coating drop." For this reason. the forward chaining of expert systems has been added to MPC in the latest applications. Courtesy: Ceme/11 Americas ,\Jay/Jun. 2002, P-16, Fax: 312-726-./107/257./ E mail: Books@primediabusiness.com Weh: 11'11'11'. cementamericas. com BELT CONVEYOR TRANSFERS- A BRIEF REVIEW S. T. Huque and A. G. McLean One of the most important areas of bulk solids handling is the efficient flow ofmaterials at transfer points wi thin the sys tem. Bulk material transfer points are found in a wide range of industries, including mtmng, mineral processi ng, chemical processing, thermal power plants and many others that deal with bulk solids. Th is paper rev iews th e progress of conveyor-to-conveyor transfer technology. Many aspects of belt conveyo r transfers, especially the various models and design method s avai lable to calcu late or predict the re levan t parameters (eg mat~ri al discharge velociti es, material s trajectories, dynamics of material impact, air entrainment) are presented. Many of the widely available methods for trajectory pred iction are compared. Existi ng models that are in acc urate in pred icting the relevant transfer point aspects, and areas where the available literature is insufficient are idelltified. Courtesy: bulk solid~ handlii1g, May/June2002, P196, Fax: 495323 96 97 96 £ mail: llp@transtech-online. com Web: ll'lt 'HI.transtech-online.com LOOK IN TilE FLAME David Hargreaves Neural nets are now seen as taking a much more promi nent role in process contro l ·op timisation. J\dd to this, the recent development of hi gh speed digital image processing of the actual kil n flame, and you now have th e buil ding blocks of a new form of kil n control system whi ch is now unde r development by a team of en thusiastic German engineers - under the company banner Powitec. In their view, detailed analysis of the visible dynamics of the actual main flame have led to some start ling resu lts which ca n co rre late into realistic assessments of c linker composition and product quality. So far this new system is now under test in a number ofGerman and Austrian cement works with recent trials affirm ing most of initial findings that flame status dictates final cement qua lity. In essence, say Powitec, digitally monitor the flame in the visib le spectrum, provide an intelligence for adaptive learning and standby for some rapid improvements in cement product quality, higher ki ln availability. reduction in fuel consumption, greater use of secondary fue ls pl us some appreciable savings in producti on costs due to a more stabilised kiln operation. Couriesy: International Cement Re1•iell'. July 2002 P43, E-mail: inforij_~CemNef co.uk Weh site: CemNet. co. uk PREHEATER IMPROVEMENT Walter Kronawetler, PMT– Zyk!ontechnik Gmbh, Austria PMT- Zyk lontechnik offe rs engineering for complete modification of preheater towers in order to reduce the pressure drop sign ificant ly, wh i ~h in turn will increase c linke r prod uct ion o r reduce energy costs. Waste fuel preparation plants and installation of chlorine by-pass systems are now providi ng tech nology for c lients using alternative fuels. Together with· its partners in combust ion technology, PMT-Zyklotechnik has th e availability to create the optimum solution in research, and as a result, the optimum preparation, feeding and burning during t he c linker production process. Thi s enab les the customer to fall significantl y below the offic ia l emission standa rds outlined by government regulations and allows its clients in the cement industry to use the maximum quantity of a lternat ive fue ls to reduce production costs. The HURRICLONII\) is spec ia ll y designed cyc lone m