| 摘要 |
1,169,958. Impregnating wood. BOLIDEN A.B. 16 May, 1967 [16 May, 1966], No. 22733/67. Heading D1P. In the impregnation of wood by introducing the wood into an impregnation vessel, evacuating the vessel and filling with impregnating liquid, and applying pressure to the liquid, the pressure is applied in two or more stages, using at least one high capacity low pressure pump in one stage and at least one low capacity high pressure pump in a subsequent stage. All the pumps may be initially in operation and progressively disconnected, or they may be operated in succession. The pressure pumps may be centrifugal pumps and the vacuum pump may be a liquid ring pump. The maximum pressure applied may be 8-14 kg/cm<SP>2</SP>. In an automatic process, a vacuum pump 11 is employed to evacuate a cylinder 1 containing wood and to draw impregnating liquid from a reservoir 2 via a line 3 and a valve 4 into cylinder 1 and a vacuum tank 13 connected thereto by a three-way cock 9. When the liquid reaches a predetermined level in tank 13, valve 4 is closed and cock 9 is operated to connect reservoir 2 to cylinder 1 via two parallel high and low pressure pumps 6 and 7 respectively. Until a pressure of 7 kg/cm<SP>2</SP> is reached, both pumps operate, whereafter the maximum pressure is attained using pump 6 only. When the desired maximum pressure has been reached, a by-pass valve 5 opens, thus maintaining a constant pressure in cylinder 1. At the end of a predetermined time for pressure impregnation, pump 6 ceases operation, valves 4 and 19 are opened and cock 9 is returned to the vacuum position, thus allowing liquid to drain back from cylinder 1 to reservoir 2. |
