Cement, Energy and Environment

Improvement in Kiln Productivity through Diagnostics Study • NCB Experiences Rabindra Singh, Naga Kumar, Ramachandra Rao, Prateek Sharma National Council for Cement and Building Materials 1.0 INTRODUCTION Cement kiln performance is dependent on a number of factors such as variations in quality of raw materials mined, fineness and particle size distribution of ground raw materials, various modulii values of kiln feed , coal quality and its variations. Ash content, volatile matter, Moisture content and fineness of fuel , besides process and operating parameters of kiln-preheater-calciner and cooler operation also influence the kiln productivity. A number of cement plants suffer from problems such as poor quality of clinker and cement, unstable kiln conditions, inappropriate design capacity of primary air fan and burner, improper flame , inadequate capacity of calciner, discrepancies in design and installation of preheater - calciner-cooler system, poor heat recuperation of cooler etc. leading to sub-optimal productivity of plants. Inordinate delay on the part of the plant in addressing such problems leads to reduced profitability besides increased energy consumption and deterioration of cement quality. NCB carried out kiln optimization studies for a Plant in the Southern part of India for a 1.5 million tonne kiln capacity. The result of the optimization has been spectacular for the kiln in terms of improvement in quality and productivity. The production of the kiln increased from the existing level of 5000tpd to 5500tpd and above with significant improvement in clinker quality. The paper highlights the efforts of NCB towards process optimization leading to improved productivity, quality and energy efficiency. 2.0 CASE STUDY 2.1 Problem Discussion The kiln, equipped with 6 stage preheater and precalciner supplied by FLS, is 4.35 m ID x 67 m long with rated capacity of 4500 TPD clinker and was producing around 5000 TPD clinker as against the maximum production achieved to the tune of 5500tpd . The plant has been experiencing the problem of high free lime in clinker, coating formation in burning zone, yellow core formation in the clinker and dusty kiln conditions. 2.2 Observation: Kiln condition before and after implementation of NCB recommendations are given in Table 1. Our observations are as under: Table 1: Kiln condition before and after Free lime High fluctuations in free lime Brought down to acceptable level of clinker Yellow core problem of Yellow core in Reduced yellow core clinker Dusty clinker Highly dusty Improved granulometry of clinker 24