Cement, Energy and Environment

Selection Table- 1 Technical Specification of VRM A Vertical Raw Mill was selected to be the best option. Discussions were held to decide the source for supply of new VRM. Since the cost of mill from proven suppliers was very high, decision was taken to search for alternative from China. ITEM UNIT SPECIFICATION Model name TRM31.3 Dia of grinding table MM 3100 Table speed RPM 34.87 Dia of grinding roller MM 1650 Team of Engineers visited China for the purpose and held discussion with leading suppliers of China. Major challenges faced were: Nos of grinding roller No.s 3 Gear box power Kw 1250 Motor rating a) Reliability of major components, b) Smooth operation at desired output. Finally based on references, visit to manufacturing site and comparing of technical data, M/S TCDRI was preferred for sourcing of new mill. JKLC technical team was actively involved from designing stage of the Mill circuit to ensure the achievement of above requirements. To ensure the quality of product JKLC officials visited China four times during manufacturing of mill. Major sub-assemblies were shop assembled and gear box was test run in presence of JKLC officials. During such visits, faults were observed in rocker arm and grinding table which were attended to by M/S TCDRI. M/S TCDRI also attended to any suggestions made by JKLC officials. VRM (TRM 31.3) Introduction The Raw grinding system has been designed to produce 180 TPH Raw Meal at 15% residue on 901-l and also with aim to minimize the energy consumption and to lower the amount of equipment to an absolute minimum by making a very simple and compact lay out. TRM series vertical roller mill is a kind of roller mill with 3 grinding rollers. Each grinding roller unit is composed of fixed rocker arm, rocker arm supporting and hydraulic system. We have jointly decided to design table RPM 10% higher as compared to norms of renowned supplier so that we can get higher output from small mill to reduce overall project cost but that was a risk . To mitigate the risk, we have added one more resistance in the circuit. The Designed parameter of Chinese VRM is shown in Table-1 .: Kw 1400 Working Principle VRM TRM series vertical roller mill is used for raw grinding. Raw material is sent to feeding duct through air lock valves. Feeding duct goes into VRM inside via side face of classifier. Raw material falls to the center of grinding table by forces of gravity. The grinding table is firmly fixed with gear box and runs at constant rotation speed. Constant rotations of grinding table enables uniform distribution and make even bed of raw material on grinding table. Inclined conical arranged grinding rollers press material for grinding. Under function of hydraulic system, raw material is ground by compressive stress and friction forces. Under centrifugal force, raw material continues to move towards periphery of grinding table . On the table periphery the material falls and is picked up by air steam. The ground material is carried upwards to dynamic classifier. During this process , heat exchange takes place between ground material and hot gas which eliminates moisture down to 1% within finished raw material. The off-spec material is separated by classifier and sent back to grinding table. The final product is taken and sent by gas flow generated from VRM fan into filter. Process Description The feed mix to mill is extracted through weigh feeder to ensure a metered feed. The raw material is fed to Mill through belt conveyors to the mill 1/L. Magnetic separator and metal detector are installed in the mill feed belt conveyor to remove any stray metal/metal particles. Rejects from the mill are taken back to the feed belt by recirculation bucket elevator. 2 "--