A VOCATIONAL TRAINNING REPORTSubmitted in partial fulfillment of the requirements for

the award for the degreeOf

BACHELOR OF TECHNOLOGYIn

CHEMICAL ENGINEERING By

AMAN KUMAR KESARI

INSTITUTE OF TECHNOLOGYGURU GHASIDAS VISHWAVIDYALAYA, BILASPUR

05/05/2015 – 30/05/2015

A Brief Introduction To Bhilai Steel Plant

The Bhilai Steel Plant, located in Bhilai, in the Indian state of Chhattisgarh, is India's first and main producer of steel rails, as well as a major producer of wide steel plates and other steel products. The plant also produces and markets various chemical by-products from its coke ovens and coal chemical plant. It was set up with the help of the USSR in 1955.

The plant is the sole supplier of the country's longest rail tracks, which measure 260 metres (850 ft). The plant also produces products such as wire rods and merchant products. Bhilai Steel Plant has been the flagship integrated steel plant unit of the Public Sector steel company, the Steel Authority of India Limited and is its largest and most profitable production facility. It is the flagship plant of SAIL, contributing the largest percentage of profit.

VISION:• To be a respected world class corporation and the

leader in Indian steel business in quality, productivity, profitability and customer satisfaction.

CREDO:• Building lasting relationships with customers

based on trust and mutual benefit.• Uphold highest ethical standards in conduct of our

business.• Create and nurture a culture that supports

flexibility, learning and is proactive to change.• Chart a challenging career for employees with

opportunities for advancement and rewards.• Value the opportunity and responsibility to make a

meaningful difference in people's lives.

FLOW CHART OF BHILAI STEEL PLANT

CO & CCD DEPARTMENT The main function of Coke Ovens is to convert coal into coke which is used as a fuel and reducing agent in the Blast Furnace. Its secondary function is to recover Volatile Matter and CO gas from coal and extract chemicals known as Coal Chemicals. CO gas produced is used for heating purposes in the plant. The Coke Ovens and Coal Chemical Department has three main sections viz. I. Coke Ovens II. Coal Chemicals III. Maintenance and Repairs The description of each of these sections is given below : COKE OVENS :

Various sub-sections of Coke Ovens and their functions are as follows : 1. Coal Handling Plant (CHP-I) and Coal Preparation Plant (CPP-II) :To prepare coal blend suitable for carbonisation in Coke Ovens Batteries to produce BF coke. 2. Partial Briquetting : To prepare briquettes of coal to charge along with coal into the oven. 3. Coke Oven Batteries : To convert coal into coke by carbonising coal in absence of air and thereby distilling the volatile matter out of coal. The resultant coke oven gas is treated in CCD for recovery of chemicals. 4. Coke Sorting Plant : To crush and screen coke to 25-80mm size required by blast furnaces. The 0-10 mm fraction is used in sinter making and 10-25 mm fraction (nut coke) is added along with sinter supplied to Blast Furnace.

RAW MATERIALS USED FOR COKE PRODUCTION

PRIME COKING COAL MEDIUM COKING COAL IMPORTED COKING COAL SOFT COKING COAL

COAL PROPERTIESPCC MCC ICC SOFT

ASH 18-24 19-24 8.5-11.0 8.5-11.0

VM 24-25 27-29 22-24 32-35

MMR 1.0-1.1 0.9-1.0 1.15-1.30 0.85-0.95

SULPHUR 0.5-0.6 0.5-0.6 0.65-0.95 0.6-0.7

PARTIAL BRIQUETTING OF COAL CHARGE : The basic process involves briquetting a part of coal charge (28% by weight) with coal tar (soft pitch) and charging the briquettes and fine coal in a pre-determined ratio (25 : 75). The rationale for using briquettes in charge is to increase the bulk density of coal charged into the oven and to improve the micum index and crushing strength of coke.

COKE OVEN BATTERIES : There are eight coke oven batteries 4.3 M tall having 65 ovens in each battery (in 2.5 MT stream) and two batteries 7 M tall having 67 ovens in each (4.0 MT stream). These are twin flue regenerative, compound PVR (Pair Vertical recirculation) and side fired type.

The temperature of control verticals flues on pusher side is 1175°C to 1225°C and 1200°C to 1250°C on coke side. These however can be increased or decreased depending upon the coking time.

Coke ovens are mainly constructed of silica, fireclay, high alumina and ordinary insulating bricks. The coke oven chimney is made of concrete lined with fireclay bricks. Normal life of a coke oven battery under indian condition is considered to be 25 years.

The heating of ovens is done from both the sides in side fired batteries with reversal of heating.

The coal is taken in charging car from the coal tower and is charged into the empty oven. Each oven has three charging holes and each charging car has three bunkers for charging of coal into the ovens.

Coke is made by heating coal in the absence of air ( carbonization / destructive distillation of coal) in a series of ovens called batteries.

Coal blend to Battery

Coal in an oven converted to coke

Coke pushing

The process of conversion ….

Firing of spilled Coke

Mechanized door cleaner

Manual cleaning of frame

IMPORTANT DATA OF BATTERIES

ANALYSIS OF COKE OVEN GAS Methane - 26.0% Hydrogen - 56.5% Hydrocarbons - 2.3% Carbon-monoxide - 8.5% Carbon dioxide - 3.0% Oxygen - 0.4% Nitrogen - 3.3% Density - 0.4848 kg/ m3

Description Battery(1-8) Battery(9&10)Total length of oven 14,080 mm 16,000 mmTotal height of oven 4300 mm 7000 mmUseful height 4000 mm 6700 mmNo. of ovens 65 67Width on Pusher side 382 mm 385 mmWidth on Coke side 432 mm 485 mmAverage Width 407 mm 410 mmUseful volume 21.6 Q.M. 41.6 Q.M.

IMPORTANT SAFETY RULES FOR WORKING IN CO&CCD

• Do not travel on belt conveyors.• If some Coal/Coke piece enters the eye, do not rub.

Wash it with water and go to medical post.• Beware of free moving wagons.• Do not stand on any machine tracks.• Quenching car and pusher car, power trolley lines which

are within the reach of hands should not be touched.• Do not go under quenching tower. Do not put your hands

in hot quenching water.• Do not stand over a charging hole lid.• Double security check is exercised for entry to benzol

rectification plant. Persons with matches or nailed shoes are not permitted to enter the area.

• In case of acid burn, wash in running water and rush to hospital.

• Wear cotton clothes only.• All PPE (Personal Protective Equipments) provided by the

management be utilized without fail.

BLAST FURNACESINTRODUCTION – Iron Production Basics: BF is a counter current heat and mass exchanger, in which solid raw materials are charged from the top of the furnace and hot blast is sent through the bottom via tuyeres. The heat is transferred from the gas to the burden and oxygen from the burden to the gas. Gas ascends up the furnace while burden and coke descend down through the furnace. The counter current nature of the reactions makes the overall process an extremely efficient one. In the blast furnace process iron ore and reducing agents (coke, coal) are transformed to hot metal, and slag is formed from the gangue of the ore burden and the ash of coke and coal. Hot metal and liquid slag do not mix and remain separate from each other with the slag floating on top of the denser iron. The iron can then be separated from the slag in the cast house. The other product from the Blast Furnace is dust laden blast furnace gas, which is further cleaned in the gas cleaning plant and is used as a fuel all over the plant.

Blast Furnace constructional features:

A blast furnace has a typical conical shape. The sections from top down are: Throat, where the burden surface is. The shaft or stack, where the ores are heated and

reduction starts. The bosh parallel or belly and The bosh, where the reduction is completed and the

ores are melted down. The hearth, where the molten material is collected

and is cast via the taphole.

Fig1: Schematic cross- section of blast furnace

BLAST FURNACE PROCESS: The basic raw materials and their functions: Iron Ore: Iron bearing materials; provides iron to the

Hot Metal.Sinter: Iron bearing material. Fines that are generated

in the plant are effectively utilized by converting them to sinter. Provides the extra lime required for the iron ore that is charged in the blast furnace.

Coke: Acts as a reductant and fuel, supports the burden and helps in maintaining permeable bed.

Limestone: Acts as Flux. Helps in reducing the melting point of gangue present in the iron bearing material.

Manganese Ore: Acts as additive for the supply of Mn in the Hot Metal.

Quartzite: Acts as an additive.Coal Dust: Acts as an auxiliary fuel, reduces coke

consumption in the BF.

Coal Tar: Acts as an auxiliary fuel, reduces coke consumption in the BF.

Pellets: Iron bearing materials. Although not in use right now, there is a proposal to utilize the fines below the sinter grade for pellet manufacturing and the pellets formed are going to be charged in the BF.

Reactions in the Blast Furnace:

UPPER STACK ZONE

Reduction of Oxides 3 Fe 2O3 + CO = 2 Fe3O4 + CO2

Fe3O4 + CO = 3FeO + CO2

FeO + CO = Fe + CO2

Decomposition of Hydrates Water - Gas Shift Reaction CO + H2O = CO2 + H2

Carbon Deposition Decomposition of Carbonates

MIDDLE STACK ZONE Direct / Indirect Reduction FeO + CO = Fe + CO 2 CO2 + C = 2CO FeO + C = Fe + CO Gas utilization LOWER STACK ZONE Calcination of Limestone Reduction of Various elements

Reduction of unreduced Iron Reduction of Silicon

Reduction of Mn, P, Zn etc. . Formation / melting of slag, final reduction of FeO and

melting of Fe.

< 600°C

600-900°C

900-1100°C

> 1100°C

COMBUSTION ZONE Burning and combustion of Coke C + O2 = CO2 + 94450 cal (direct reduction) CO2 + C = 2CO - 41000 cal (solution loss reaction) Complete reduction of Iron Oxide

RACEWAY Coke and Hydrocarbons are oxidized. Large evolution of heat.

HEARTH Saturation of Carbon with Iron. Final Reduction of P, Mn, Si and Sulphur. Reaction impurities reach their final

concentrations. Falling/drop of Metal and Slag bring heat down

into the Hearth.

HOT METAL SLAG BF GAS

Si 0.5-0.8 % SiO2 32-33 % CO 25-26 %

Mn 0.8-1.0 % Al2O2 19-20 % CO2

15 -16 %

S0.04 % max. CaO 31-33 % N2 55-57 %

P 0.20% MgO 9-10 % H2 2-3 %

C 4-5% MnO <1%

Basicity:

CaO/SiO2 0.98

ANALYSIS OF HOT METAL, SLAG AND TOP GAS