Importance

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Abstract

In a continuous digester system the chip feed equipment is greatly simplified by substituting a single vertical vessel for the conventional chip bin, steaming vessel and chip chute. An outlet at the bottom of the single vessel is connected, through a low pressure pump, to the low pressure input of a high pressure transfer device which is connected to a digester (either directly or through an impregnation vessel). A metering device, preferably through a pressure isolation device for maintaining superatmospheric pressure in the vessel, feeds chips into the top of the vessel. A first level, of chips, is established in the vessel and a second, liquid, level below the first level is also established. Steam is supplied to a volume between the top of the vessel and the second level utilizing a conduit with an automatically controlled valve and a temperature controller for at least partially controlling the valve. A level controller controls the supply of liquid to the vessel and is connected to the low pressure outlet from the high pressure transfer device. There is a reduction in cross-sectional area of the vessel of greater than 50% between the second level and the outlet at the bottom of the vessel. Alternatively, the pump from the bottom of the vessel may be connected to one or more batch digesters.

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First Claim