再循環式鑄型乾燥爐について

抄録

  In drying of moulds emphasis must be placed on the uniformity of temperature distribution in the furnace as well as the economy in fuel.
  To this aim the author made experiments on two methods. The one is the recirculating combustion method of the exhaust gas (hereafter be referred to as the recirculating combustion method) which uses a part of the exhaust gas in the coal-fired furnace together with the combustion air, and the other is a method which recirculates and diffuses the exhaust gas in the combustion chamber by means of a blower (hereafter be called as the recirculating diffusion method.)
  The recirculating combustion method effected on an economy of coal by 35 to 40 per cent. This was due to the lowered igniting temperature resulted from the increase in the air temperature, the reduction in the loss heat of the exhaust gas, and the diminition of cinder.
  The uniformity of temperature distribution in the furnace, however, showed no difference from the old method.
  Since it could be realized simply and effectively by increasing the drying hot air quantity, the hot air was increased by recirculating and inducing the exhaust gas in addition to its simultaneous forced diffusion.
  The adoption of the recirculating diffusion method enabled a better uniformity of the temperature by reducing the temperature variation from 130∼100°C to 60∼90°C, but the consumption of coal increased due to the use of the low temperature exhaust gas.
  From the above experiments the combination of recirculating diffusion and recirculating combustion (hereafter be called as the recirculating diffusion combustion) was employed to obtain a better uniformity of temperature distribution in the furnace without increasing the consumption of coal.
  The moisture in the drying hot air was doubled by the recirculation of the exhaust gas without delaying the crying time. The drying of moulds became uniform, and the formation of cracks and adhesion of soot on mould surfaces were prevented.