Feeding arrangement for feeding of chips to chip bins
View Patent ↗The invention relates to a feed arrangement for feeding chips to chip bins ( 1 ) in the production of cellulose pulp in continuous digesters ( 16 ), in which the chip bin is constituted by a treatment vessel having a top and a bottom, in which the chips are fed into the top ( 13 ) of the treatment vessel and fed out via the bottom of the treatment vessel using suitable lock members ( 10, 11 ). Distribution devices ( 4 a, 4 b ) for the addition of steam are disposed in the treatment vessel so as to heat the chips to a level above 80° C., preferably around 100° C., when the chips are fed out via the bottom of the treatment vessel. By virtue of the fact that the chips are fed into the treatment vessel via at least one liquid lock ( 30 ) and the treatment vessel is otherwise sealed off, the quantity of driven-off gases from the chip bin is reduced to a minimum, at the same time as an effective utilization of available energy is obtained.
1. A method of feeding wood chips to a treatment vessel for production of cellulose pulp, comprising:
providing a liquid lock having a liquid disposed therein forming a first liquid surface, a bottom of the liquid lock and a second liquid surface, the liquid lock being upstream of a treatment vessel,
the liquid of the liquid lock blocking air passage through the liquid lock to or from the treatment vessel,
feeding untreated or un-steamed wood chips at essentially ambient temperature down to the liquid lock and forming a chips column on the first liquid surface,
advancing the chips column of wood chips through the first liquid surface,
passing the wood chips through the liquid lock for driving off all free air surrounding the wood chips and preventing essentially all free air from passing the liquid lock,
feeding the wood chips through the second liquid surface,
the wood chips, essentially being without any free air disposed around the wood chips, tumbling down through a down-pipe to the treatment vessel without compressing the wood chips,
exposing the wood chips to steam to remove air bound in the wood chips from the wood chips so that a quantity of air which is drawn with the wood chips to the treatment vessel is reduced to a minimum, and
heating the wood chips to at least 80° C. in the treatment vessel prior to discharging the wood chips from the treatment vessel.
2. The method according to claim 1 wherein the method further comprises monitoring a liquid level of the liquid in the liquid lock.
3. The method according to claim 2 wherein the method further comprises providing additional liquid when the liquid level falls below a minimum predetermined liquid level.
4. The method according to claim 1 wherein the method further comprises maintaining a minimum liquid level in the liquid lock.
5. The method according to claim 1 wherein the method further comprises detecting a liquid level in a liquid lock and generating an alarm when the liquid level falls below a minimum liquid level.
6. The method according to claim 1 wherein the method further comprises adding steam to the treatment vessel.
7. The method according to claim 6 wherein the method further comprises regulating the added steam by a control valve.
8. The method according to claim 1 wherein the method further comprises measuring a temperature of the chips and maintaining a temperature of chips at a bottom of the treatment vessel above 80° C.
9. The method according to claim 8 wherein the method further comprises maintaining a temperature of the chips at a top of the treatment vessel below 80° C.