| 摘要 |
<p>Steel pipes have to be protected against corrosion by a covering. To this end, the tubes are shot blasted and heated to receive this covering. Heating is conventionally effected either by induction, or by gas burners, placed in a muffle which is passed through by tubes. These two processes operate with a thermal efficiency of the order of 30%. According to the technology of the present invention, the tubes to be heated pass through a cylindrical furnace equipped on the inside with turns which free the passage of the tubes. A generator of hot gases under high compression delivers these gases tangentially into the furnace. The gases circulate between the turns in rotational movement at great speed. Positioned btween the turns are deflectors which capture a stream of hot gases to deflect it in the radial direction, accelerating it at the same time. The deflected gases strike the tube tangentially and heat it by virtue of rapid renewal of the boundary layers. The circulation of the hot gases and the tubes is methodical therefore, in counterflow, which makes it possible over the long distance, to remove the gases at a relatively very low temperature. A thermal efficiency in excess of 60% is thus achieved.</p> |
