Patent DE-19905716-A1 (DE)
Title: Stock inlet has structured part-flows to give required turbulence and be set to vary pulp parameters without affecting total flow volume and without developing high internal hydraulic forces
Inventor: LINK CHRISTOPH
IPC: D21F1/02
Filed: 1999-02-11
Abstract: To generate a turbulence in the pulp flow (26) at a single- or multi-layer stock inlet, at least two part-flows (20,22,24) are brought together and mixed.  The part-flows are brought together at an angle. The momentum of the mixed part-flows is the required momentum of the pulp flow in the flow direction. The part-flows are brought together in a designated mixing zone, with or without integrated mixing units. To set the level of turbulence, the flow cross section and/or the feed pressure and/or the consistency of at least one part-flow (20) is altered as required. A gap (32,34) is formed at the mixing zone (40), preferably at the start of the outlet channel (14) in the stock inlet (10) to take the mixed part-flows (20,22,24). The flow cross section adjustment of at least one part-flow (22,24) is by sections or together through the gap (32,34) across the machine width, and the gap height (36,38) is altered accordingly at right angles to the machine width. The stock inlet (10) takes at least two part-flows (20,22,24) of a different consistency and/or temperature and/or pressure and/or flow speeds. The consistency of at least one part-flow (20,22,24) is altered by initial dosing, and the other part-flows are adjusted to give a constant total volume flow. The initial dosing is by sections, across the machine width, and at least partially in the stock inlet (10) or at least partially in front of the stock inlet (10) in the flow direction (L). The parameters for the level of turbulence are set by a control system. At least one part-flow is used with thickening matter and at least one with extracted water from the pulp, so that the stock inlet (10) has at least one part-flow (20) with extracted water and at least two part-flows (22,24) with thickening matter. At least one part-flow (20,22,24) is accelerated in front of the stock inlet (10) at least to the outlet speed. The flow of mixed part-flows (20,22,24) in the outlet channel (14) is at a speed where no additional acceleration is required. An Independent claim is included for a stock inlet with a center unit (12) fitted with connections (16) for at least two part-flows (20,22,24). The part-flows (20,22,24) are brought together to be mixed, to generate turbulence in the pulp flow (26), especially in front of and/or at the start of the outlet channel (14).  Preferred Features: At least one part-flow (22,24) opens into a compensation chamber (28,30) across the machine width, between the center unit (12) and the outflow channel (14). The chamber (28,30) is linked by a gap (32,34) with the outflow channel (14) for the mixed part-flows (20,22,24). The gaps (32,34) have an adjustment to set the level of turbulence. The gaps (32,34) are near a mixing zone (40) at the start of the outflow channel. A further part-flow (20) opens directly or indirectly into the mixing zone (40), which is a dedicated chamber with or without integrated mixing units. The gaps (32,34), for the chambers (28,30) are on a common plane at right angles to the flow direction (L), to bring the part-flows together at an angle. The gaps (32,34) can be in succession in the flow direction (L). The outflow channel (14) has two facing lips (42), parallel or at a slight angle to each other. At least one lip can be adjusted for height and/or the flow direction angle, which also sets a gap (32,34) linking a chamber (28,30) with the outflow channel (14) at the same time. The center unit (12) has channels (44,46,48) through it for at least two part-flows (20,22,24), with flow connections (16). One center channel (44) opens directly into the mixing zone (40) at the start of the outflow channel (14), and at least one further center channel (46,48) opens into a chamber (28,30) linked by a gap (32,34) with the mixing zone (40). The center channels (44,46,48) are defined in sections across the machine width. Connecting lines (50) are at the feed lines (52,54) between the center channels (44,46,48) for the part-flows (20,22,24) and/or between different part-flows. At least one dosing unit is at a connecting line (50) to vary the consistency of at least one part-flow (20,22,24) without a change in the total volume flow. At least the affected center channels (44,46;44,48) of the center unit (12) are interconnected by sections. The center unit (12) has a modular structure relating to width and/or height. The various sections of at least one channel (44) through the center unit (12) are separated from each other by thin walls, and especially of sheet plate and the like. The dividing wall plates match the local cross section shape of the center unit (12). The passage channel (44) can be defined by two modules inserted between the dividing walls, with a channel (46,48) through at least the upper or lower module. The module is secured to the side walls of the center unit (12) by a number of tie anchors (64). The center unit (12) has a cover plate (70) and a base plate (72), preferably mounted to the modules. A connecting plate (74) is fitted to the cover and base plates (70,72) to hold the feed lines (52,54) for the part-flows (20,22,24) to move into channels (76) towards the machine width. The gap (32,34) is formed between the center unit (12) and the lip (42), and the chamber (28,30) and is defined by an outer flexible wall (80). A lever assembly (78) is at the center unit (12) for each lip (42). It has at least one lever (82), which pivots on an axis (84) on a shaft (86) in eccentrics on bearing pedestals (98) or especially bolts which have a linear sliding movement, together with at least one slide guide (88) at the center unit (12) supported by the lever (100). For a multi-layer stock inlet, the outlet channel is divided into part-channels by at least one blade. The part-flows are led into each part-channel without additional acceleration. The center unit (12) is linked to concentric distributors through the connected feed lines (52,54).