ABOUT COKEOVEN CONSULTANCY

Cokeoven Consultants (P) Ltd. specializes in designing, erection and implementation of heat recovery coke ovens for producing LAMC, BF Coke & Foundry Coke for steel industry. The company started in 1984 by Mr. Anand Agarwalla and later other technical consultants for civil and structure joined the company. All possess a highly qualified experience specifically for non recovery/ heat recovery coke ovens. We offer integrated design and engineering consultancy services from concept to completion for a wide range of projects in the coal washery and coke oven industries, furnaces, heat and energy conversation.

Cokeoven Consultants (P) Ltd. offers an unparalleled depth of experience in Hard Coke Oven and washery industry, furnace and refractory industry. Comprising of employees more than 20, our technical staffs have an average of 20 years experience and our erection technicians have an average of 19 years of experience. This vast experience translates to market and application knowledge unequalled in the industry.

INTRODUCTION
A world class blast furnace operation demands the highest quality of raw materials, operation, and operators. Coke is the most important raw material fed into the blast furnace in terms of its effect on blast furnace operation and hot metalquality. A high quality coke should be able to support a smooth descent of the blast furnace burden with as little degradation as possible while providing the lowest amount of impurities, highest thermal energy, highest metal reduction, and optimum permeability for the flow of gaseous and molten products. Introduction of high quality coke to a blast furnace will result in lower coke rate, higher productivity and lower hot metal cost.

COKE PRODUCTION
The cokemaking process involves carbonization of coal to high temperatures (1200°C) in an oxygen deficient atmosphere in order to concentrate the carbon. The commercial cokemaking process can be broken down into two categories: a) Byproduct Cokemaking and b) Non-Recovery/Heat Recovery Cokemaking.

In Non-Recovery coke plants, originally referred to as beehive ovens, the coal is carbonized in large oven chambers The carbonization process takes place from the top by radiant heat transfer and from the bottom by conduction of heat through the sole floor. Primary air for combustion is introduced into the oven chamber through several ports located above the charge level in both pusher and coke side doors of the oven. Partially combusted gases exit the top chamber through "down comer" passages in the oven wall and enter the sole flue, thereby heating the sole of the oven. Combusted gases collect in a common tunnel and exit via a stack which creates a natural draft in the oven. Since the by-products are not recovered, the process is called Non-Recovery cokemaking. In one case, the waste gas exits into a waste heat recovery boiler which converts the excess heat into steam for power generation; hence, the process is called Heat Recovery cokemaking.
 

COKE PROPERTIES
High quality coke is characterized by a definite set of physical and chemical properties that can vary within narrow limits. The coke properties can be grouped into following two groups: a) Physical properties and b) Chemical properties.

a) Physical Properties:
Measurement of physical properties aid in determining coke behaviour both inside and outside the blast furnace In terms of coke strength, the coke stability and Coke Strength After Reaction with CO2 (CSR) are the most important parameters. The stability measures the ability of coke to withstand breakage at room temperature and reflects coke behaviour outside the blast furnace and in the upper part of the blast furnace. CSR measures the potential of the coke to break into smaller size under a high temperature CO/CO2 environment that exists throughout the lower two-thirds of the blast furnace. A large mean size with narrow size variations helps maintain a stable void fraction in the blast furnace permitting the upward flow of gases and downward of molten iron and slag thus improving blast furnace productivity

b) Chemical Properties:
The most important chemical properties are moisture, fixed carbon, ash, sulphur, phosphorus, and alkalise. Fixed carbon is the fuel portion of the coke; the higher the fixed carbon, the higher the thermal value of coke. The other components such as moisture, ash, sulphur, phosphorus, and alkalise are undesirable as they have adverse effects on energy requirements, blast furnace operation, hot metal quality, and/or refractory lining. Coke quality specifications for one large
Blast furnace in North America are shown in Table I.

Table I. Coke Quality Specifications:

FACTORS AFFECTING COKE QUALITY
A good quality coke is generally made from carbonization of good quality coking coals. Coking coals are defined as those coals that on carbonization pass through softening, swelling, and resolidification to coke. One important consideration in selecting a coal blend is that it should not exert a high coke oven wall pressure and should contract sufficiently to allow the coke to be pushed from the oven. The properties of coke and coke oven pushing performance are influenced by following coal quality and battery operating variables: rank of coal, petrography, chemical and theological characteristics of coal, particle size, moisture content, bulk density, weathering of coal, coking temperature and coking rate, soaking time, quenching practice, and coke handling. Coke quality variability is low if all these factors are controlled. Coke producers use widely differing coals and employ many procedures to enhance the quality of the coke and to enhance the coke oven productivity and battery life.