METHOD AND SYSTEM FOR FEEDING COMMINUTED FIBROUS MATERIAL

A system and method for feeding comminuted cellulosic fibrous material such as wood chips to the top of a treatment vessel such as a continuous digester (11) provide enhanced simplicity, operability, and maintainability by eliminating the high pressure transfer device conventionally used in the prior art. Instead of a high pressure transfer device the steamed and slurried chips are pressurized using one or more slurry pumps (251, 251I) located at least thirty feet below the top of the treatment vessel and for pressurizing the slurry to a pressure of at least about 10 bar gauge. A return line (235) from the top of the digester may, but need not necessarily, be operatively connected to one or more pumps and if connected to the pumps the pressure in the return line may be reduced utilizing a pressure reduction valve (58) and/or a flash tank (253). Steam from the flash tank may be used in steaming the chips. Pressure relief prevention may be provided by isolation valves (65-69) in the lines leading to and from the top of the treatment vessel controlled by a controller (69) which is responsive to the pressure sensed in the slurry line leading to the top of the treatment vessel. Un sistema para producir pasta química de celulosa de material de fibras de celulosa desmenuzadas, que comprende: un recipiente de vaporización (121, 321) en el cual el material de fibras de celulosa desmenuzadas es vaporizado para extraerle el aire; y un recipiente (11) de tratamiento vertical a presión superatmosférica que tiene una entrada (13) para una suspensión de material de fibras de celulosa desmenuzadas en una parte de arriba de éste y una salida en una parte de abajo (15) de éste; y caracterizado por un medio de transferencia presurizante para presurizar una suspensión de material del recipiente de vaporización y transferirlo a dicha entrada del recipiente de tratamiento, consistiendo dicho medio de transferencia presurizante en una o más bombas de alta presión (251, 251', 351, 351') para suspensión situadas debajo de dicha parte de arriba de dicho recipiente de tratamiento y estando desprovisto de un alimentador de alta presión, mezclador o recipiente de calentamiento indirecto.