A Journey Towards Excellence in The Blast Furnace Performance at Jayaswals Neco Limited.

Transcription

1 A Journey Towards Excellence in The Blast Furnace Performance at Jayaswals Neco Limited. History of iron making at Jayaswals NECO limited is only 10 years old. JNL set up a blast furnace of 650 ³ in the year 1995 viewing to set up an integrated steel plant of one million ton in the land of chhattisgarh. The total land of 1200 acres was acquired for this project. The basic design and the part of equipments were supplied by M/s Shougang Corporation China and the consultants to the whole project were M/s M.N.Dastur & Co.Kolkata. The project started in the year 1995 and was completed in record time of 22 months from Bhoomi poojan. Blast furnace was commissioned in the month of Nov The rated capacity of 941 tons per day (Productivity 1.72 tons / M³) and the fuel rate of 700 Kgs/thm was achieved in a short span of three months from commissioning. Continuous development over the past ten years brought radical improvements in blast furnace performance in terms of productivity, coke rate and quality of hot metal. The table for productivity, coke rate and others achievements speaks the volume of efforts that has been put in pursuit of development.the developments in the area of raw materials, refractories, modification & additions of latest equipments and operating philosophy completely changed the complexion of iron making scenario at NECO Jayaswals The blast furnace was commissioned with the below mentioned facilities. The blast furnace complex is divided into two parts i.e. major and auxiliary facilities The major facility include raw material handling system, stock house, top charging equipments, hot blast stove BF proper, cast house.the auxiliary facility include power plant, blower station, gas cleaning plant with gas holder, slag granulation and disposal system, pig casting machine power supply and control system, Instrumentation and automatic control system, water supply and drainage system, compressed air supply system, steam injection system, conveyor system, dust collection system, maintenance and repair shop, testing laboratory, communication system and ladle repair facilities etc. The furnace is basically designed with rational arrangement and simplified construction. The total plant is free from pollution, which is a prime object of any steel plant in the present scenario. JNL has his own railway siding with a wagon tippler of capacity to unload 18 wagons per hour. To cater the need of the handling the raw materials for enhanced production, a truck tippler of handling capacity more than 2000 mt per day was introduced in the system. Further in addition to the above a manual unloading siding was also developed. One stacker cum reclaimer is there to feed to blast furnace & sinter plant. Provision to feed the blast furnace & sinter plant through trippers was also introduced viewing to the excessive load on stacker cum reclaimer. The thrust on the maintenance is such that the stacker cum reclaimer runs nonstop for 22 hrs a day. The stock house was designed for the production of 1000 tons of hot metal in BF. This area was modified by installing high efficiency feeding & screening system along with suitable programming to meet the requirement of BF so that it can cater to the need for producing more than 2000 tons of hot metal per day. A mini skip was also installed to take care of spillages in the skip pit. The screens are so efficient that undersize material limits to maximum of 1%. The furnace was commissioned with a double bell system and a rotary distributor at the top. In the year 2004 this was replaced with Bell less top of Chinese make considering the importance of distribution of materials inside the BFand the advantages production & fuel rate. This compact BLT is similar to the Paul wurth BLT. The accuracy of charging can be compared with any other BLT in the world. Steelworld November

2 The stoves are designed to get the hot blast temperature of C This is atypical Chinese design with ceramic burners at the bottom of combustion chamber and 7 honey comb type checkers in order to get prolong campaign life of hot blast stove An addition system of preheating the combustion air by introducing a recuperator in flue gas line was done in the year 2001 This has helped us to increase the hot blast temperature by another 35 C. This was designed to produce 941 mt/ day with a complete control of charging system, auto change over of stoves and monitoring of various pressure & temperature at different levels etc. are being done by distributed control system. To predict and to have better control over the hearth erosion a model was developed in-house in the year The other inhouse models developed in the past years are burden control & optimization models, burden distribution model, tapping management model, kinetic simulation model etc. After the BLT was installed an over burden camera was installed. For other feedbacks for the distribution of materials at the top an over burden temperature probe along with on line CO monitor was also installed. The better gas distribution along with vigil monitoring and further in improving the operating discipline the production improved to 140 % and the reduction in fuel was by 10%. Graphical representation of productivity & fuel rate since commissioning This plant is based on simple technology of double ventury system. The cleanliness of BF gas is up to the level of 5 mg/m³. The top pressure was earlier designed for 0.8 bar but in the year 2005 this system was modified to take care up to 1.0 bar. There is a gas holder of capacity m³ to sustain line pressure fluctuation and also to retain the gas availability to the consumers in case of reduction in blast for a short period. The gas is so effectively utilized in power plant, stoves & sinter plant that the flaring of gas is restricted to zero. The pig casting machine was commissioned along with the blast furnace in the year 1996.There are two pig casting machine with 4 numbers of strand, each strand consists of 300 moulds and each mould is having 4 pockets. The capacity in total is to handle 1800 tons of hot metal per day. The average weight of pigs is in the range of 8 to 10 kgs, which is in high demand. The JNL pigs are rated to be one of the best in India due to the metallurgical quality & its appearance (clean & black) with lightweight. The pig yield in the initial years was up to the level of 92% but in the recent years the yield has gone high up to 98%which is one of the best figures not only in India but in abroad too. This could be possible with the continuous research and development, time management, recirculation of ladle scraps & increasing the efficiency of man skills through these years. Ladle repair shop is in the same premises of pig casting area. The average ladle life is more than 800 heats (42% alumina bricks), which was earlier in the range of 500 heats. This could be possible with improved backup lining, improved design in the striking zone and strictly monitoring of circulation of hot ladles to avoid heat loss. The ladle capacity was earlier of capacity 65 mt but now it has been changed to carry 80 mt to meet the requirement of handling higher tonnage of hot metal in same numbers of ladles Graphical representation of pig yield since commissioning Steelworld November

3 Initially the area was design to handle 1000 mt of hot metal with the provision of 3 metal spouts. By modifying the design of main runners, metal runners, diversion dams and slope of runners along with skimmer the present capacity is capable to handle more than 2000 mt comfortably. Initially the skimmer life was restricted to mt of hot metal but in the recent years the life of skimmer was enhanced as high as 1,25,000 mt. This could be achieved by modifying the design of skimmer with changing the ramming mass from tar bonded to specially designed resin bonded mass. The furnace with equipped with single tap hole and the average of 12 cast per day is maintained judiciously. The not dry casts are less than 0.1% The power plant consists of two turbo blowers in parallel having capacity to blow 2000 nm³/minute Three boilers of 30 t capacity with three turbo generators to produce 15.5 mega watts power Internal consumption is in-between 10 to 11megawatts rest is being exported to CSEB. The reliability of turbo blowers or we may say the maintenance are such that only two incidence of tripping has occurred in last 10 years. Raw Materials : As we all know that Good raw material quality forms the essence of any iron making scenario The most important step for maintaining stable operation is feeding the furnace with consistent good quality burden materials and coke in appropriate manner so as to obtain good stack permeability for the gas flow. In the absence of any captive mines of our own, we outsource every raw material either from India or abroad. Earlier the main component of the iron-bearing burden was iron ore only and that are received from many sources. The iron ore were received mostly from Orissa sector, since the requirement was voluminous; the quality of ore in respect to alumina & fines started deteriorating. In house modification in RMHS system was done to reduce the fines at transfer points. Quality iron ore price started shooting up. Then a strategy was decided which was based on techno economics, to limit the sources viewing to the quality & the landed cost. Considering the realization of in-house generated fines and the market value of the fines a planning was made to set up a sinter plant. The vision came in the existence, when sinter plant of 36 m² was commissioned in the mid of the year This sinter plant was designed to replace around 40% of iron ore from the burden. The rated capacity of 1.35 tons /m² was achieved in a months time. The total flux required in the BF was made through sinter route The decision for going up for a sinter plant helped us to increase the productivity of BF by 10 12% and the decrease the coke rate by 8 to 10%. In the year 2005 the market of fines started going up due to export and the quality fines scarcity was viewed. The fines available in the market were of low Fe and high alumina that was a big constraint in good sinter making. Looking to the scenario mill scale addition in sinter making was introduced and today we have reached the level of usage to 250 Kgs/ton of sinter. Many in-house modifications in sinter plant like steam injection in raw mix before sinter machine, hot air provision above sinter machine, better water distribution at MND, better distribution of raw mix by modifying the roll feeder etc. has resulted in higher productivity i.e. from 1.35 to 1.8 tons /m²which can be said to be one of the best in India. The sinter contribution in the furnace burden went high up to 50%. The increase in sinter production had further added its value in hot metal production in BF The crucial role of coke in blast furnace operation is well known. The coke was imported from China right from commissioning of BF. Earlier the ash of coke was in the range from 13 to 15% but after going through the techno economics the procurement was further revised to the ash range from 11 to 13%, which is still continuing. In the meantime lot of trials were made for cost economics i.e. coke from BSP, IISCO Burnpur, Durgapur, cookeries of dhanbad (Private ovens) were tried time to time. The coke was also imported from Japan, Russia, and Australia etc. time to time depending upon the coke price in the international market. The usage of nut coke of size 10 25mm in BF was started in the year The use of 40 to 60 kgs/thm has now become the regular phenomena Use of as much as 120 kgs/thm nut coke has also been tried without any adverse effects. Viewing to the volatile coke market in the year , coking coal was purchased from international market and was converted to coke in different coke ovens at dhanbad, cuttack & Kolkata area. In the mean time to have a control over the quality of coke a facility of testing CSR, CRI & micum was added in our own laboratory. The same crisis of coke leads us to divert the thinking for other alternatives i.e. oil injection in the furnace The thinking was changed to fact with in a short period of 2 months. The oil injection system was commissioned in the month of April The total investment was in the tune of only 6 lacs. This was total an in-house project which was 18 Steelworld November 2006

4 successfully achieved. The oil used was LSHS. The replacement ratio was in the level of 1.3 to 1.4 and the use was in the range of 60 to 70 Kgs/thm. This decision has really paid us when the coke price in the international went high as 425$ per ton. In the same scenario the usage of DRI in BF up to the level of 25% in the burden was done. This has given a great relief during the crisis of coke & its price hike in the market. Now the situation was forcing us to move towards other alternatives of coke procurement from international market. This has induced us towards coal injection & our own coke ovens. The coal injection system was commissioned in the month of February The capacity of the system was to grind and inject 16 tons per hour i.e. more than 150 kgs/thm. The system was equipped with the latest technology of grinding & injection. Here the issue of high light is the grinding of coal without HGG. In the past one & half years operation hardly any time the HGG is being utilized. The system is being run with heat of the flue gas, which was earlier exposed, to the atmosphere. The initial stabilization took 3 to 4months but after that the system was utilized in a full-fledged manner. With in the six month of commissioning the rate of injection went high up to 100 Kgs/thm that too without oxygen. With oxygen enrichment of 1.5% the injection went to the maximum level of 145 kgs/thm. It is to note that whenever our steel melting shop is under maintenance the oxygen is totally diverted to BF, which is equal to 1.5% of enrichment. Graphical representation of PCI rate in last 18 months a provision of expanding to the level of 0.4 million tons. It is towards the way of stabilization and soon the coke ovens are committed to produce coke of international standards. Reduction of alkali input in blast furnace is one of the most important criteria to ensure smooth operation of BF The presence of alkali deteriorates mechanical strength of coke in the lower part of the blast furnace, causes scabs formation thereby affecting smooth burden descent and attacks refractory linings. The alkali input was, therefore was drastically lowered by judicious selection of raw materials and reducing their specific input rate from a level of 6.5 kgs/thm to 3.5 kgs/thm. It was established that for every one-kilogram drop in alkali loading, BF productivity increased by 0.2 t/m³/day. The alkali buildup inside the furnace has been restricted by a controlled operating practice. The other hidden facts for the level of performance are the maintenance system of the total unit. Integrated maintenance system with flat organization structure has been introduced in recent years. The excellence of preventive maintenance are such that breakdown seldom occurs. On line maintenance are done in many places. Earlier the preventive maintenance of equipments was done in once in a month with a prepared shutdown of 24 hours. But in the recent years the shut down for maintenance is done once in two & half months with a reduced time of 20 hours. The total maintenance & spares management are linked with computerized system. The kind of maintenance & operations being done at JNL that has lead the furnace campaign life of 10 years without category one repair is a live example in India. The present level of production is in the range of mt/day i.e. Productivity of 3.2 to 3.4 tons/m³. The fuel rate is 540 kgs/thm including the average coal injection more than 100 kgs/thm. The plant was started in a green paddy field and during the last ten years more than 1.0 million of trees have been planted all around the plant. Beautiful gardens are being developed in each section of the plant. There is a central garden consisting of birds & animals with aquarium full of colored fishes attract the visitors during their visit to plant. The gardens with different type of flowers, fruits developed all around the working area create congenial & homely feeling to the employees. The housekeeping level of the plant is also excellent. The plant is free from dust & pollution. The coke ovens of stamp charged non-recovery type was commissioned in the month of January It is the first of its kind in India. The present capacity is 0.1 million ton which has To meet the international benchmarking of the productivity of 4.0 t/m³/ day with a fuel rate of kgs/thm which includes the coal dust injection of 150 to 200 kgs/thm. To meet the targets following projects are in the line: Steelworld November

5 1) Modification of furnace during category 1 repair planned in the year ) High top pressures to be raised from present 1 bar to 1.4 bar during the category one repair. 3) Hot blast temperature to be raised from 1000 C to 1200 C by suitable modification in existing stoves. 4) Second sinter plant to cater the need of 80 % in theburden 5) Pellet plant to feed remaining 20 % in the burden.latest technology Iron fines beneficiation plant to get good quality of fines for making sinter & pellets. Iron making in NECO Jayaswals has made a remarkable progress in last two years. Continuous development and timely implementation of several measures have helped to achieve the present high-level performance in blast furnace and also to create a new milestone in the country. Considerable improvements in raw material quality, and timely decisions for new developments in the recent years have paid rich dividends in the up gradation of blast furnace performance. This along with several changes brought about in operating philosophy, introduction of latest technology & equipments, instruments with several design modifications have proved the fact that it is possible to achieve high level of performance in Indian blast furnaces with raw materials that are largely different from the same being used by other developed countries. Lastly the vision of to be one of the best in the world with a concern of lowering the cost of production in Jayaswals NECO around which the efforts are on to achieve more than that what has been thought of. - Buyer Seller Meet - SKM Steels Ltd. Authorised Distributor for Tata Tiscon & Tata Steelium (CRCA Products) 305-A, Apollo Tower, 2 M. G. Road, Indore Phone # / / Fax # marketing.indore@skmsteels.com Raneka Industries Ltd. -: An ISO 9001:2000 Organisation :- Class A Foundry as per IS approved by RDSO/Lucknow (Ministry of Railways - Govt. of India) -: Main Products :- Various Kinds of Steel Castings / SG Iron Castings / Other Special Castings in a Weight Range of 1Kg to 1500 Kg Specialization in Railway Components Like : HS, CONCOR / NLB -: REGD. OFFICE :- 303, Navneet Plaza, 5/2, Old Palasia, Indore (M.P.) Phone : , , Fax : , , ; Cable : CM Metals ISHAN Copper Pvt. Ltd. RAJSHANTI Metals Pvt. Ltd. Ishanraj, Shed No. 464, G.I.D.C., Shanker Tekri, Jamnagar Tel. : , B-42, G.I.D.C. Shanker Tekri, Udyognagar, P. O. Box No. 705, Jamnagar (Guj.) Tel. : / Fax : rajshanti@sancharnet.in Web. : FERRO SCRAP NIGAM LIMITED FSNL Bhawan, Equipment Chowk, Central Avenue, Post Box No. 37, Bhilai CHHATISGARH Tel. : / (P &T) 4036 / 4037 (BSP) Fax : / fsnl@sancharnet.in Website : / NAVDURGA ISPAT (P) LTD. The Quality Manufacturer of Steel Structure Gilders mm x 70mm mm x 65mm mm x 75mm mm x 100 mm Channel x 75 mm x 65 mm x 75 mm -: For Trade Inquiry Contact :- MR. MUKESH PANDEY Cell. No. : / A, Sec.-C, Urla Industrial Area, Raipur (C.G.). Ph. : , Fax : Bellary Engineering & Consultancy Services Pvt. Ltd. -: Project & Process Consultancy for :- Sponge Iron Plant / Pellatization Plant / Power Plant / Iron / Ore Benification Plant 1st Floor, Srinivasa Complex, 3rd Cross, Vidya Nagar, Airport Road, Bellary , Telefax : , Ph : becs2@rediffmail.com / becs123@rediffmail.com -: BRANCH OFFICE :- 316, Niligiri Block, Aditya Enclave, Ameerpet, Hyderabad - 38 Tel. : / Cell : Steelworld November 2006