Process and apparatus for circulating backwater in a papermaking machine
First Claim
1. A process for making paper or board while recycling backwater in a papermaking machine, the machine including a short circulation wherein the backwater draining through a paper forming fabric of the machine is used for papermaking stock dilution, the process comprising:
- splitting at least a portion of the backwater draining through the forming fabric into at least two separate backwater flows; and
pumping each of said backwater flows directly and separately without passing through any open air-containing vessels, such that said backwater flows are substantially air free separate flows to at least two essentially separate points of short circulation stock dilution.
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Accused Products
Abstract
The invention relates to a process and an apparatus for recycling backwater in a papermaking machine. According to the invention backwater draining through a forming fabric is collected into several collecting means (51, 52, 53, 54) and pumped by separate pumps (20) in at least two and preferably numerous separate flows (81 to 85) directly as substantially air free separate flows to the fibre process (12, 30, 40) of the short circulation in order to implement a fast, air free and split recycling of backwater from said forming fabric to said fibre process.
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Citations
31 Claims
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1. A process for making paper or board while recycling backwater in a papermaking machine, the machine including a short circulation wherein the backwater draining through a paper forming fabric of the machine is used for papermaking stock dilution, the process comprising:
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splitting at least a portion of the backwater draining through the forming fabric into at least two separate backwater flows; and pumping each of said backwater flows directly and separately without passing through any open air-containing vessels, such that said backwater flows are substantially air free separate flows to at least two essentially separate points of short circulation stock dilution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus for circulating backwater in a papermaking machine having a short circulation, the machine comprising
at least two stock dilution devices in flow communication with the short circulation, a headbox (50), a looped forming fabric (60), at least two separate backwater collecting means (51, 52, 53, 54; - 51A, 52A, 53A,
53) for collecting backwater draining through said forming fabric (60), at least two of said collecting means being in direct flow communication with a respective pump (20;
20,
21) for returning backwater collected therein directly and separately without passing through any open air-containing vessels, such that the backwater is in a substantially air-free condition, to said at least two separate stock dilution devices (12, 30, 40;
111, 112, 113, 114, 115,
116) or substantially separate water distribution means in flow communication with the stock dilution devices (80),whereby a fast, air free and split recycling of backwater is implemented. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
- 51A, 52A, 53A,
Specification