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   Energy Conservation Tips on Steel re-rolling mill
 
Furnace :
  • Control Excess air with oxygen at 3% level in flue gases. A 10% drop in excess air amounts to 1% saving of fuel in furnaces. For an annual consumption of 1000 kilo liters of furnace oil, means a saving of over Rs. 1 lac.
  • Normally flue gas temperature is beyond 5500C. To recover waste heat install recuperator of required capacity.
  • Install missing doors of the furnace and ensure sealing to avoid radiation losses.
  • Do not heat stock on visual inspection basis. Install temperature instruments to control furnace temperature at soaking and heating zones in order to achieve.

a. Fuel saving.
b. Reduction in scale loss.
c. Eliminate probability of total material rejection.

  • Put cap on burner block holes after removing the burner if not in use. This will avoid ingress of excess air.
  • Install Flow meters and pressure gauges at furnace oil service tank exit.
  • Hire a suitable flue gas analyzer and check all the parameters at least once in a month for proper combustion in the furnace. Ideally once a batch.
  • Close furnace doors properly after charging the blooms into the furnace.

Insulation :

  • Improve insulation & refractory of the furnace. Re-line the doors and insulate hot lines also.
  • Insulate valves and flanges to minimize the heat loss. Insulation is to be of boxed type for maintenance ease. Observation shows that a furnace operating at a temperature of 10000C and keep its doors open results in a fuel loss of 1 Ltr./hr. For a 1000 hrs. furnace operation this translates into a loss of approx Rs. 1 Lac per year.
  • Improve insulation if the surface temperature exceeds 600C. Ensure that proper insulating material and thickness is provided for proper insulation.
  • Arrange or ask for Industrial training programme on refractories in your cluster once in a year.

Recuperator :

  • · Overhaul the recuperator of re-heating furnace at regular intervals to ensure recovery from flue gases and improve the combustion. Ideally once in six months.

Fuel Handling and Operation :

  • For efficient combustion pre-heat the oil to have temp between 1050-1100C at burner tip and optimize air to fuel ratio.
  • To stop abrasive particles FO filtration system should have filter mesh sizes as follows.

a. Between Lorry & main storage tank-mesh size 10
b. Between service tank & pre-heater- mesh size 40
c. Between pre-heater and burner- mesh size 100

  • Provide water draining facility and regularly drain water. This reduces sludge formation and other problems like erosion of burners and damage to the refractories.
  • It is preferred to have parallel FO pumps of smaller capacity than one pump of larger capacity to avoid unnecessary re-circulation of huge quantity of FO.
Burners :
  • Use thin film burners in place of conventional burners. Burners should be dismantled and cleaned frequently, preferably once in a shift. Good thin film burners have been developed by PCRA & IIP Dehradun which increases energy transfer from primary air to fuel oil to 70%.

Flue Gases :

· Use high temperature flue gas to increase the stock temperature from 4500 upto 7000C before entering the dryer. This decreases the process time and increases production.

Power Factor :

  • Improve power factor by regular checking of current of all the capacitors and their timely replacement.

Motors :

  • Avoid idle running of rolling mill motors & fans.
  • Provide canopy on all outdoor motors.

Lighting :

  • Replace 40W Tube light by slim 28W Tube light and electromagnetic choke with electronic choke.
  • Replace 400 Watt Mercury Vapour lamps with 250 Watt sodium vapour lamps or 250 W metal hallide lamps.
  • Replace 250 Watt Mercury Vapour lamps with 150 Watt sodium vapour lamps or 150 W metal hallide lamps.
  • Provide more transparent sheet instead of asbestos sheets to use natural light.
Contract Demand :
  • Provide demand controller with an alarm provision in case it exceeds contracted demand.

General

  • Wherever possible try to produce particular type of product for longer period. This increases productivity.
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