GB1505042A - Apparatus for the preservation of wood - Google Patents

Abstract

1505042 Wood impregnation apparatus SADOLIN & HOLMBLAD A/S 30 June 1976 [3 July 1975] 27247/76 Heading D1P [Also in Divisions F3 and F4] Wood impregnation apparatus is provided with a refrigeration system for condensing solvent vapours e.g. methylene chloride from a post-impregnation vacuum step. The apparatus comprises a thermally insulated storage tank 3 for impregnation liquid, an impregnation tank 1 for containing wood to be treated and provided with heating wires 2, pipes 4, 7 for transferring impregnation liquid from the tank 3 to the tank 1 and vice versa, means preferably comprising a liquid ring (mineral oil) vacuum pump 18 and an ejector 16 for removing vapours from the impregnation tank end introducing the vapours via a tank 19 into first and second condensers 23, 26 connected in series, and pipes 28, 30 for returning condensate to the storage tank. The refrigeration system comprises a compressor 44 having two evaporators 47 and 27. The evaporator 47 is placed in a circuit containing a brine tank 49. Brine is circulated by a pump 48 and may be directed through a cooling coil 24 in the first condenser. The second evaporator is located in the second condenser 26. The compressor is operated to chill the brine in the tank 49 e.g. to -5‹C during the steps of the impregnation process wherein no vapours are formed. Upon withdrawal of hot vapours from the tank 3 by the pump 18, the compressor is operated to chill the second condenser, the first condenser being chilled by the reservoir of previously cooled brine. A cooling coil 53 connected to the brine tank is provided in an oil reservoir 20 associated with the vacuum pump 18. A condenser 54 dumps heat from the compressor 44 in the storage tank which may be supplementarily heated by a heat exchanger 57. Make-up compound may be added to the recycled condensate in a tank 32. Hot liquid is pumped from the storage tank via the pipe 4 by a pump 6 into the wood-containing airtight impregnation tank which has previously been evacuated by the pump 18. The desired temperature may be maintained using the heating wires 2 and a superatmospheric pressure by closing valve 13. After impregnation is complete, residual liquid is returned to the tank 1 via the pipe 7 and the valve 8 is closed. Valves 13 and 15 are then opened and solvent vapours are sucked into the condensers 23, 26 by the pump 18. Entrained air can escape from the condenser 26 via a pipe 58. Outlets 42, 43 from the condensers 23, 26 are connected to the suction side of ejector 16 mounted in pipe 12 upstream of the pump 18 and downstream of the valve 15, which is a one-way valve, to provide a forced flow of vapours through the condensers.