«Department of Mechanical Engineering National Institute of Technology Rourkela Rourkela,2014 HEAT TRANSFER ANALYSIS OF BLAST FURNACE STAVE COOLER ...»
HEAT TRANSFER ANALYSIS OF BLAST
FURNACE STAVE COOLER
M.Tech. Thesis Submitted to
National Institute of Technology, Rourkela
SAMEER KUMAR BEHERA
ROLL NO: 212ME3310
Department of Mechanical Engineering
National Institute of Technology Rourkela
HEAT TRANSFER ANALYSIS OF BLAST
FURNACE STAVE COOLERM.Tech. Thesis Submitted to National Institute of Technology, Rourkela Under the guidance of (Prof. S. K. SAHOO) Department of Mechanical Engineering National Institute of Technology Rourkela Rourkela,2014
CERTIFICATEThis is to certify that the thesis entitled, “HEAT TRANSFER ANALYSIS OF BLAST FURNACE STAVE COOLER” submitted by Sameer Kumar Behera in partial fulfillment of the requirement for the award of the degree of Master of Technology Degree in Mechanical Engineering with specialization in Thermal Engineering at the National Institute of Technology, Rourkela (Deemed University) is an authentic work carried out by him under my supervision and guidance.
To the best of my knowledge, the matter embodied in the thesis has not been submitted to any other University/ Institute for the award of any degree or diploma.
Prof.S.K.SAHOO Department of Mechanical Engineering NIT Rourkela
ACKNOWLEDGEMENTI express my deep sense of gratitude and indebtedness to my supervisor Dr. S. K. Sahoo, Professor of Department of Mechanical Engineering for his extensive support throughout this project work. His timely help, constructive criticism, and conscientious efforts made it possible to present the work Contained in this thesis. Working under him has indeed been a great experience and inspiration for me.
I would also like to thank Mechanical Department specially Dr. M. K. MOHARANA who has given idea about project. I express my sincere thanks to Mr. Tapas ranjan mohanty and shaibu, PhD Research Scholars.
Sameer Kumar Behera
Place:NIT Rourkela 212ME3310
ABSTRACTFurnace cooling technology is very important for the metallurgical industry as it cansignificantly increase productivity and campaign life of furnaces. A heat transfer mathematical model of a BF staves cooler has been developed and verified by the experiments. The temperature and heat dissipated by stave cooler will be calculated by using ANSYS. The results has corroborated with experimental model used in RSP Blast Furnace.
In this work heat transfer analysis has been done at different temperatures (loads) from 573k to 1723k in order to compare which material of staves has given better results than the other, also nitrogen has used in stave coolers of a Blast Furnace in the place of water for cooling purposes.
Figure 1.1 Thermal Zone of Blast Furnace
Figure 1.3 Setup of Plate cooler in Rourkela Steel Plant(RSP)
Figure 1.2 plate cooler
Figure 1.4 Inner view of plate cooler
Figure 1.5 Cigar cooler
Figure 1.6 Arrangment of Cigar Cooler
Figure 1.7 Stave cooler with lining
Figure 3.1 Three Dimentional Stave cooler of Blast Furnace
Figure 3.2 Cooling pipe of stave cooler
Figure 3.3 Stave cooler arrangement in Blast Furnace
Figure 3.5 Thermocouple arrangement in RSP
Figure 4.1 Thermocouple arrangement in RSP
Figure 5.1 Compare between Experimental data and Numrical data
Figure 5.2 Compare Temprature difference(dT) between Nitrogen and Water
Figure 5.3 Compare maximum temperature between cast iron,copper and aluminium
Figure 5.4 Compare maxium temperature between cast iron and copper using nitrogen
Figure 5.5 Temperature Contours of cast iron stave with nitrogen
Figure 5.6 Temperature Contours of copper stave with nitrogen
Figure 5.7 Compare maxium temperature between cast iron and copper using Water
Figure 5.8 Temperature Contours of cast iron stave with water
Figure 5.9 Temperature Contours of copper stave with water
Figure 5.10 Graph shown Max temperature on cast iron stave at different zone of Blast Furnace.
........... 37 Figure 5.11 Graph shown Max temperature on copper stave at different zone of Blast Furnace............... 37 Figure 5. 12 Heat flux on the hot face of stave from stack to belly position of Blast Furnace................... 38 Figure 5. 13 Total heat extraction from stack to belly position of Blast Furnace.
Figure 5.14 Temperature of water cooling pipe at a various point.
Figure 5.15 Temperature of nitrogen cooling pipe at a various point.
Figure 5.16 Temperature of nitrogen and water cooling pipe in cast iron stave
Figure 5.17 Temperature of nitrogen and water cooling pipe in a copper stave.
Figure 5.18 Temperature contours of cooling pipe
LIST OF TABLEDescription Table 3.1 Dimension of Stave Cooler
Table 3.2 Dimension of casting coil in a stave
Table 3.3 Different metal used in stave cooler
Table 4.1 HeatExtracted measurement of stave Coolers Bosh position Raw I & II
Table 4.2 Heat Measurment of Hearth cooler in RSP
Table 4.3 Heat measurement of Hearth cooler (LHB) in RSP
Nomenclature K Thermal Conductivity of material, (W/mK) Cp Specific heat of fluid, J/kgK L Total length of stave, m Area of stave,m2 A m Mass flow rate,(Kg/s) Heat flux experienced at hot face of stave, (w/m2) q,, Q Heat extracted by the stave,(w) dT Temperature difference (K) Re Reynolds number D Diameter of cooling pipe,(m) Greek symbols
LIST OF FIGURE
LIST OF TABLE
1.1Types of Cooler
1.1.1 Plate cooler
1.1.3 Stave cooler
220.127.116.11Types of stave cooler
1.2 Colling Process of Blast Furnace
1.3 Objective of Present Work
2 LITERATURE REVIEW
3 THREE DIMENTIONAL MODELING OF BLAST FURNACE STAVE
3.1 Model of Blast Furnace cooling stave
3.2 Computational modeling of cooling stave
4 EXPERIMENTAL AND NUMRICAL ANLYSIS
4.1 Numerical Analysis
4.1.2 Boundary conditions of stave cooler for thermal calculation
4.2 Experimental study
4.3 Formula used for calculation
4.4 Summery of Exeperiments
5 RESULTS AND DISCUSSION
Chapter 1 Introduction
CHAPTER 11 INTRODUCTION
A stave is a cooling device having one or more coil,which is used to cool the refractory lining.
It is installed in numbers on the inner surface of a blast furnace to protect its steel shell and maintain the inner profile but copper staves have been installed in blast furnaces in the zones exposed to the highest thermal loads,Thrmeal laod of stack to belly shown Fig.1.1.In blast furnace lots amount of heat is generate because of combustion, hence lining cooling by stave technology is one of the products of such efforts.It prevent from the overheating and subsequent burn through. In Cooling system Water is used as a medium for removes the excess heat generated in the blast furnace which keep the lining cooled & prevent it from faster wearing out.
Cooling system thus prevent the increase of the shell and lining temperature. Various methods exist for cooling of the shell for the blast furnace. The staves were made conventionally of cast iron. But now days copper staves are used in place of cast iron staves, which is excellent in heat conductivity and heat flux to the copper staves is 50% lower than that to cast iron staves. Cast iron staves are proven cooling elements that are capable of multiple campaign life in areas of the blast furnace which do not experience extreme heat loads. Copper staves are proving to be an effective and reliable blast furnace cooling element that are subject to virtually no wear and are projected to have a longer campaign service life in the areas of highest thermal load in the blast furnace.
Now a days, cooling boxes of different size, number and design were used for transferring heat of the furnace to a cooling medium in conjunction with spray cooling. Blast furnaces with cast iron cooling staves are operating since 19 century. Cast iron stave cooling was originally a Soviet discovery from where it travelled initially to India and Japan. By 1970, cast iron cooling staves have attained world wide acceptance. Since the introduction of these cast iron stave coolers, the development work of blast furnace cooling got accelerated and today a wide variety of coolers are available for the internal cooling of the furnace shell to suit extreme condition of stress in a modern large high performance blast furnace.
1.1Types of Cooler 1.1.1 Plate cooler In Europe plate cooler has been used in all large furnace. Plate coolers are generally made by either welded or cast in electrolytic copper. The usual plate sizes are 500 - 1000 mm long, 400 mm wide and approximately 75 mm high,which is shown in below Fig.1.2. Plate cooler has kept in the zones with high heat loads of blast furnace especially in the bosh and lower stack areas,arrangement of plate cooler shown in below Fig.1.3 and 1.4.Copper flat coolers have a greater uniformity of material properties over the complete cooling element. These coolers are designed to maintain high water velocities throughout the cooler, thus have an even and high heat transfer coefficient. The copper flat plate coolers generally have multiple channels with one
or two independent chambers. One of the designs of capper flat plate cooler has six pass with single chamber. These coolers are mostly welded to the blast furnace shell to ensure gas tight sealing Minimum losses of water pressure are ensured in both the piping and the element itself The figure of a commoncopper flat plate cooler design.
1.1.2 Cigar cooler For special blast furnace applications, Cigar Coolers can be either cast or fabricated in many different dimensions or lengths,the design of Cigar cooler shown in below Fig.1.5. These are also called as copper jackets. Cigar coolers are used in between the plate coolers when more intensive cooling is required or there is more spacing of the flat plate coolers,which is shown in Fig.1.6. These are also used forimprovements to the existing cooling system during a campaign.Cigar cooler is generally machined by solid copper bar to form a cylindrical core and a single channel is added by drilling and plugging. Cigar coolers are normally kept on the centerlines between adjacent flat plate coolers on a horizontal and vertical plane. For the basis of installation of a cigar cooler normally a cylindrical hole is drilled through the furnace shell and
existing refractory lining with a core drill.The cigar cooler use increases the cooling system area and prevents the refractory lining to chemical and mechanical attack mechanism.
1.1.3 Stave cooler Copper staves were developed by Japan and Germany in the mid 1990s but the greater number of the installations is in or after 2000.Dimension of copper stave are 1640mm,900mm and 200mm length, breath and height respectively.Typical design of stave cooler shown in below Fig.1.7.Copper stave are use in the region of bosh, belly and lower stack to cope with high heat loads and large fluctuations of temperatures. Stave cooler of Japan are cast copper staves, but German copper staves are rolled copper plates having close outer tolerances and with drilling done for cooling passages. Drilled and plugged copper staves are normally designed for four water pipes in a straight line at the top and four water pipes in a straight line at the bottom.
Internal pipe coils made by monel, copper or steel.
18.104.22.168Types of stave cooler Smooth Surface stave cooler -Ithaving good thermal conductivity and simple structure the hot face is smooth face. It is mainly used in the front of tuyere and inner lining of BF hearth cooling.
Common Brick stave cooler-it ismostly used in bosh, belly and middle and lower part of stack.
Brick inlaid is high alumina brick, silicon carbide brick and etc. hot face of this kind of stave is spacing lined refractory brick.
Common Ramming stave cooler-The hot face of stave is spacing lined dove tail with crushing refractory materials inside, and is mainly used in bosh, belly and middle and lower part of stack.
Complete Cover Brick stave cooler- stave is completely covered by bricks with thin or non lining structure to enlarge the furnace volume. It is mainly used in bosh, belly and stack.
1.2 Colling Process of Blast Furnace Water is come from high level tank of plant to the stave cooler at high velocity due to gravitational force. These stave cooler are designed in a closed loop rather than the conventional open systems. This allows the pipe work to be chemically cleaned, and by controlling water chemistry throughout the campaign this clean surface can be maintained, thus ensuring maximum heat transfer. The main function of the cooling system of blast furnace is to cool the furnace shell and prevent it from overheating and subsequent burn through. To accomplish this, the cooling system must be able to take up the excess heat generated by the furnace and loaded onto the shell. This heat will lift the shell and lining temperature too high if the cooling system is