Increase the Cooling Efficiency of Casting Furnace Stave Cooler with Use of Experimental and Analytical Analysis

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1 e-issn Volume 2 Issue 4, April 2016 pp Scientific Journal Impact Factor : Increase the Cooling Efficiency of Casting Furnace Stave Cooler with Use of Experimental and Analytical Analysis Kishor Baldaniya 1, Kartik Trivedi 2 1,2 Mechanical Engineering, LJIET(Ahmedabad) Abstract Furnace cooling technology is very important for the metallurgical industry as it can significantly 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 Blast Furnace. Keywords Stave cooler, Furnace cooling, replace water to nitrogen I. 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, Thermal load of stack to belly. 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. 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. Figure 1. stave cooler in All rights Reserved 208

2 II. WORKING AND THREE DIMENSIONAL STAVE COOLER OF BLAST FURNACE The biggest thermal zone of the blast furnace is concentrated within the lower stave region of the blast furnace. Cooling stave bring in major maintenance and repair of a blast furnace. Hence, cooling stave life is a key parameter for the life of the blast furnace. The body of the blast furnace is made of steel and cooling stave is made of cast steel. Cast steel is used because cast steel are like high thermal conductivity, specific elongation, melting temperature, tensile strength. Cooling staves situated against the internal face of the shell between this latter and the refractory coating fulfill a double function. The staves are made of copper, steel, cast iron elements having a one coil or group of tubes in which the cooling fluid like a water or nitrogen circulates. The cooling fluid, in the prior art, is a water or nitrogen, and it is subjected to a vaporization up on contact with the heat flux which the stave cooler is to be extract. A. Objective Figure 2. Three Dimensional Stave cooler of Blast Furnace Study, Design, To analyze the behaviour of stave material at different loads, The Numerical results is corroborate with experimental model used in industry Blast Furnace, Nitrogen is use in the place of water for cooling. III. DESIGN METHODOLGY A. Computational modeling of cooling stave The main objective of the study is to analyze the behaviour of stave material at different loads using the heat transfer analysis by ANSYS [15].The above three dimensional cooling stave has to be modeled by constructing a model that has been modeled in the Creo 3.0, the dimension of stave cooler and cooling coil shown in table 3.1 and 3.2 respectfully. Table 1.Dimension of Stave Cooler Part Thickness Width Height Stave Body 100 mm 450mm All rights Reserved 209

3 Table 2.Dimension of casting coil in a stave Part Diameter Length Casting coil 150mm 4210mm Table 3.Different metal used in stave cooler Metal K (w/mk) ρ (kg/m3) Cp (J/kgk) Copper Cast Iron Fig 3. Stave cooler arrangement in Blast Furnace Cooling Stave are arranged in a loop, which are connected in a series the above figure 3.3 shown how to connect two or more than two stave. In this figure one is inlet and another is outlet from inlet water is enter to the looping of three staves and from outlet water or nitrogen is comes out, then cooling fluid passed to the cooling tank after cooling again come to the inlet it means water is ciculate. Fundamental equation for solving the fluid flow problem: 1. Continuity Equation: (1) This law applied to a fluid passing through an fixed control volume 2. Navier-Stokes Equation All rights Reserved 210

4 Above equation 2 obtained from Newton's Law of Motion to a fluid element and is also called the momentum equation. It is used to model turbulent flow, where the fluid parameters are interpreted as time-averaged values. (3) (3) (4) The above equation 4 is called as Fourier Laws of Heat conduction,which was used to calculate total heat strike on a hot face of stave. Negative sign indicate the decreasing temperature along with the direction of increasing thickness or the direction of heat flow (5) Heat flux is define as the ratio of heat and surface area of body, equation 5 is used to calculate the heat flux on the hot surface of stave body (6) These above equation are used to solve the fluid flow problem using the finite volume method in a fluent, generally energy equation is used in this problem for finding the outer temperature of stave cooler. IV. EXPERIMENTAL ANALYSIS This work about the modeling and numerical analysis of actual stave cooler used in Blast Furnace of industry.it have identified a stave cooler for experimental base, which is subjected to maximum heat load in the furnace. A analytical model has been developed with the help of software taking over all dimension from plant data base. The model developed is identical to the actual stave cooler used in furnace. Practical data have taken from experimental setup based on the same identified stave cooler. From the experimental setup we measure the actual heat load in subjective stave cooler. When All rights Reserved 211

5 same heat load calculated from experimental setup is put in analytical model in ANSYS then temperature difference (dt) Matched to be as in the actual setup. Assumption 1. Steady state conductive heat transfer process. 2. Three Dimensional. Boundary conditions of stave cooler for thermal calculation 1. Wall of stave cooler assumed to be insulated except hot wall. 2. Heat flux has given on the hot wall of stave cooler. 3. Heat flux varied according to the position of Blast Furnace. 4. Cooling fluid entered at constant temperature i.e K. 5. Mass flow rate has given to the inlet. Table 4.HeatExtracted measurement of stave Coolers Sr No. Inlet o C Outlet o C Temp Diff C Mass Flow rate Kg/s Heat Extracted(Watt) Total Heat(Watt) A. Results in Ansys V. RESULTS AND DISCUSSIONS Fig 4. Stave All rights Reserved 212

6 B. fluid domain Water is used International Journal of Current Trends in Engineering & Research (IJCTER) Fig 5. fluid domain basic Fig 6. Temperature in outlet Fig 7. Temperature Contours of cast iron stave with All rights Reserved 213

7 Fig.8. Temperature Contours of copper stave with water C. Compare between Experimental data and Numerical data Temp Differences (K) Temperature difference Vs Mass Flow Rate Numerical + Experimental Mass flow Rate (kg/s) Figure 9. Compare between Experimental data and Numerical data Summary of Experiments Temperature difference between inlet and outlet of stave cooler have obtained from experiment by the help of Thermocouple, then total heat extract by the stave has calculated using the help of equation 6.This analysis is essential for save the life of stave All rights Reserved 214

8 VI. CONCLUSION The results of the experiment data and Numerical data will be nearest and very closed. Then we have to used copper coil it gives better cooling effect to the cast iron coil because the copper have a better thermal conductivity. The copper coil gives the better result from the analytical analysis.so the temperature difference is very nearest and it is gives the cooling of the stave cooler, so automatically blast furnace life is greater and low maintenance of the furnace. REFERENCES [1] Akash Shrivastava, R.L. Himte: Computational Study of Blast Furnace Cooling Stave using Heat Transfer Analysis, IJITEE, Volume-1, Issue-6, November ISSN: [2] Wu Lijun, Xu Xun, Zhou Weiguo, Su Yunlong, Li Xiaojing : Heat transfer analysis of blast furnace stave, science direct, 26 November 2007.ISSN: [3] David Winfield, Nick Croft, Mark Cross, David Paddison : Incorporating dust lift-off Into a CFD model of a blast furnace gravity dust-catcher, science direct, 16 May 2013.ISSN: [4] Yu Zhang, Rohit Deshpande, D. (Frank) Huang, Pinakin Chaubal, Chenn Q.Zhou: Numerical analysis of blast furnace hearth inner profile by using CFD and heat transfer model for different time periods, science direct,13 August 2007.ISSN: [5] W.T. Cheng a, E.N.Huanga, S.W. Du Numerical analysis on transient thermal flow of the blast furnace hearth in tapping process through CFD, science direct, 16 July 2014.ISSN: [6] C.M. Chang, W.T. Cheng, C.E. Huang, S.W. Du : Numerical prediction on the erosion in the hearth of a blast furnace during tapping process, science direct, 25 March 2009.ISSN: [7] C.H. Lin, W.T. Cheng, S.W. Du: Numerical prediction on the variation of temperature in the eroded blast furnace hearth with titanium dioxide in hot metal, science direct 20 January 2009.ISSN: [8] E.S. Barbieri, Y.J. Dai, M. Morini, M. Pinelli, P.R. Spina, P. Sun b, R.Z. Wang : Optimal sizing of a multisource energy plant for power heat and cooling generation, science direct, science direct, 21 November 2013.ISSN: [9] Chung-ken ho, You-Zong Chen and Che-Hsiung Tung: Simulation of Heat Transfer of Defective Copper Stave with Installing Flexible Pipe or Cigar Cooler, China Steel Technical Report, No. 26, pp [10] W. T. Cheng1 and C. N. Huang1: Simulation of Iron Flow and Heat Transfer in the Hearth of a Blast Furnace. Online number 821. [11] J.I. Escalante-García, R.X. Magallanes-Rivera, A.Gorokhovsky: Waste gypsum blast furnace slag cement in mortars with granulated slag and silica sand as aggregates, science direct, 18 March 2009.ISSN: 2851 All rights Reserved 215