Reducing Fuel Consumption & Improving Refractory Lining Life In Furnace Operations

IMPROVING REFRACTORY LINING LIFE AND ENERGY SAVING IN FURNACE OPERATION By

S. P. Shenoy M.Tech, (MET. ENGG.), M.I.I.M. C.E.O., Steel Plant Specialities, 211, Raikar Chambers, Govandi East, Mumbai – 400 088 Tel. : 6797 8060, Fax : 91-22-2555 2459 E-mail : [email protected]

Website : www.esponcoating.com Hot rolling involves plastic deformation of heated metals and alloys into flat products (slabs, plates) or long products (wire rods, angles, channels, I sections, TMT bars, etc.). In this important metal forming operation, refractory and fuel for the reheating furnace (such as furnace oil, pulverized coal or gas) are the major costs. Any process or technique to reduce these costs will automatically improve the profitability of the rolling mill. The following problems are encountered in the case of refractories 1) Thermal shock cracking. Thermal shock is unavoidable in furnace operation, however much care may be taken. Due to thermal shock, cracks are initiated in the refractory lining. Energy leaks through these cracks. This loss may be as high as 33% of the total energy consumption. This is the reason why fuel consumption is observed to be more after a time gap of say, six months from the date of relining the furnace, for the same level of production. 2) Low Emissivity. Refractory lining has a low emissivity of 0.2 and hence hampers furnace efficiency. Improving this value to 0.5 or more will lead to fuel saving 3) Corrosive Action. Furnace oil contains sulphur dioxide and vanadium pent oxide. These compounds corrode the refractory lining. 4) Vicious sand blasting effect. The flame impinging on the refractory lining has a vicious effect of sand blasting. 5) Carbon deposit on the burner blocks. This problem is more pronounced when the fuel used is furnace oil. Unburned carbon deposits on the burner blocks, and over a period of time, sufficient carbon build up takes place. Due to this build up, the flame geometry is impaired and heating efficiency is lowered.

Steel Plant Specialties, a Mumbai based firm, has come out with a unique solution to overcome all the above problems. The entire refractory lining of the reheating furnace is coated with a special coating, ESPON-RC. A hot rolling mill producing 40,000 tons per annum of TMT bars has reported the following results: 1. Refractory lining life Without coating : 12 months With ESPON-RC coat : 21 months 2. Fuel Consumption: Without coating : 40 liters per ton With ESPON-RC coat : 38 liters per ton Annual saving Value of annual saving Cost of Refractory coating

: 80,000 liters : U.S. $ 35,555 : U.S. $ 1,555

Net annual saving

: U.S. $ 34,000

Fig.1 and 2 show the condition of the refractory lining and burner blocks before coating and fig. 3 and 4 show their condition after coating with ESPON-RC.

SUMMARY

1. Use of a special refractory coating holds high promises to any rolling mill which is interested in improving refractory lining life and energy saving. 2. This technique is a sure way of cost reduction.

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