Cement Energy and Environment

t Case Studie.<;; PRODUCTIVITY ENHANCEMENTOF ELECTROSTATICPRECIPITATORS S. Khan, JK Cement Works, Nimbtrhera (Rajasthan) Sll.lfMAR}' 1 tcreasingly stringent legislations in the last decade on dust emission from industrial processes, such as cement numt~{acture have necessitatetl an increasing capital expenditure on air pollution control equipment. Electrostatic precipitators (ESP) constitute one such major equipment installed at many ofthe stages of cement mamifacture to control dust emission. Operating problems, poor utilisation ofESP, or augmentation in upstream capacities wit/tout a balancing rise in ESP capacity, singly or together, affect tlte performance ofESP's resulting inltiglter dust emissions. Mls. J.K. Cement Worksfaced .melt aproblemfollowing an expansion in the production capacity. A systematic study for diagnosing tlte reasons, as a witole, for t!t e decreased performance of ESP's revealed a f ew functional bottlenecks also in the ESP's working. All these were duly addres.\·ed tltrouglt a series of simple hut lligltly effective corrective measures. As a result, the dust emissions reduced below tlte norms pre.<;;cribed by tlte State Pollution Control Board. Tlzis was achieved witlt minimum investment ami avoiding costly long plalll slwt-dmvns. In trod uct ion J KCement has three uni ts based on dry process cement technology at its Nimbahera Works with the respective rated capacities : Uni t No. I Unit No. II Unit No. III 1200 TPD 1800 TPD 4200 TPD J.K. Cement in sta lled their first ESP in Unit No. I in 1974 when there was hardly any regulationon air quality. The 400 mg/Nm 1 norm was introduced subsequently by the State Government, which JK Cement cou ld comfo11ably comply with. Un it No. II was installed in 1978-79 foliO\.ved by Unit No. III in 1982 which was st1bsequentl y upgraded in 1986-87. The plant management installed ESP 's of'capacity adequate for the then prevai Iing particulate emission norms. But the State Pollution Control Board abruptl y rev ised the emission norms from 250 mg/Nm 3 to 150 mg/Nm 3 in 1991. To comply with these, the plant management carried out a number of upgradations in the ESP's and related equipment. When the capacity of the three units was expanded, the plant management exam ined various alternati ves for remaining within the revised emi ssion norms, such as add ing one more ESP field or prov id ing another ESP alongside existing one, but both were ru led out owing to layout constraints. Faced with this situation, a number of Indian and overseas ESP expe1ts and consultants were called in tostudy the problem and suggest solutions. Modifications E ffeclcd The plant unde11ook the fo llowing major modifications in al l the ESP 's used for raw mill/ ki ln circuit in the following stages. I. Modification of ESP internals 2. Instal lationofMicromist gas conditioning system of Envirocare International , USA, to reduce gas temperature after conditioning to below 130° C vis-a-vis 170° C ofthe old syst~m . 3. Replacement ofanalog electron ic controls ofESP by microprocessor based latest controll ers and upgradation of transformer/rectifier (T/R) sets. 4. Improvement in ESP efficiency throughmax imum utilisation.