Pipe system for receiving and transporting lime sludge from a white liquor filter

Pipe system for receiving and transporting lime sludge from a filter medium in a continuously operating pressurized filter in a causticizing process, where the filter comprises at least one filter element covered with filter medium and partially immersed in white liquor mixed with lime sludge, and where white liquor is separated from the lime sludge by withdrawal through the filter medium of the filter element, each filter element comprising stripping means interacting with the filter medium for freeing lime sludge accumulated on the filter medium, and where at least one receiving chute with a first flow cross section δ1 is arranged with a receiving opening under each stripping means and above the level of the white liquor mixed with lime sludge for receiving stripped lime sludge, which receiving chute comprises an arrangement for supplying dilution liquid to the lime sludge to obtain a lime sludge concentration exceeding 15%, preferably more than 20%, characterized in that

• each receiving chute is connected to a pipe system with a second flow cross section δ2, which system is common to the chutes, and
• in which the pipe system, from the connection of the receiving chutes to the feed-out opening of the pipe system, has a flow cross section which does not exceed a third flow cross section δ3 and which maintains the flow rate in the lime sludge so that sedimentation of the lime sludge does not take place,
• in which the pipe system, seen in the flow direction of the filtered lime sludge, from the connection of the receiving chutes to a feed-out opening of the pipe system, does not have a mechanical agitator, and in which the feed-out opening has a fourth flow cross section δ4 which constitutes the smallest flow cross section of the first, second, third and fourth flow cross sections,
• and in that a counterpressure-generating means is arranged in the feed-out opening for the purpose of maintaining the pressure in the filter.