US 7,398,702 B2
	Automatic system for surveillance of coal dust supply to coal furnaces
Anders Sten Wedell, Kvistgaard (Denmark)
Assigned to Mark & Wedell A/S, Kvistgaard (Denmark)
Appl. No. 10/548,701 PCT Filed Mar. 11, 2004, PCT No. PCT/DK2004/000156 § 371(c)(1), (2), (4) Date Sep. 08, 2005, PCT Pub. No. WO2004/081539, PCT Pub. Date Sep. 23, 2004.
Claims priority of application No. 2003 00369 (DK), filed on Mar. 11, 2003.
Prior Publication US 2006/0207350 A1, Sep. 21, 2006
Int. Cl. G01N 1/00 (2006.01)

U.S. Cl. 73—863.57

17 Claims

1. Draught control unit (18) in a collector for an apparatus for the sample collection of coal dust particles being conveyed by an air current in a circular conveyor channel (1) from a coal crusher to a coal furnace, said collector (3) having unequally long distances in inner suction channels (8) extending in the collector's longitudinal direction, which suction channels (8), when the collector (3), which has been entered in the conveyor channel (1), can be caused to rotate about the axis of the channel (1) in a plane perpendicularly to the axis by a mechanical transmission, said suction channels (8) at their ends each are connected to a different suction orifice (4) with an aperture directed towards the air current in the conveyor channel (1) and which can lead a collected sample of air with coal dust particles via the suction channels (8) and further through a common tube (7) leading out through an opening in the conveyor channel (1) to a cyclone which may segregate the coal dust particles and lead them to a sample receptacle for the purpose of determining the quantity of coal dust conveyed, and where the respective orifices (4) are unequally long distances from the axis of rotation, characterized in that the collector (3) is in an inactive position between sample cycles and that a screen plate (9) is mounted upstream the common tube to protect the common tube (7) and the collector against wear caused by the coal dust particles thereby increasing the periods of time between the necessary replacements of the parts comprising the collector, the common tube and the screen plate, wherein the collector (3) is provided for effecting said sample collections and wherein the screen plate (9) is provided to protect said collector (3) and said common tube (7) against wear caused by the coal dust particles, said draught control unit (18) is of the draught control plate type for altering the cross section of a coal dust supply channel (1) with such size and in such a direction that possible differences in the coal dust conveyance of channels (1) is completely or partly reduced, characterized in that it comprises two draught control plates (19) being oppositely and symmetrically synchronously displaceable around a tube axis, whereby said plates (19) in the mounted condition of the draught control unit (18) are arranged perpendicularly to the axis of the tube, and each of which is operated by two synchronously driven motors (21) being adapted to receive control parameters from a data processor (17), and to occupy a rotating direction determined thereby during a period of rotation likewise determined thereby, and that both draught control plates (19) thus are synchronously displaceable between an outermost position in which they provide the channel (1) with a largest flow cross section, and an innermost position in which they provide the channel (1) with its smallest flow cross section.