The invention relates to a device for regulating the flow cross section in the cooling air inflows of a bulk material grate cooler for cooling a hot bulk material, such as, for example, cement clinker, with a regulator housing which is integrated into the cooling air inflow below the cooling grate and in which an actuating member moves in such a way that a rise in the flow velocity in the region of the actuating member and, along with this, an incipient rise in the cooling air throughflow quantity bring about a reduction in the free flow cross section, and vice versa.
On a cement clinker production line, the hot cement clinker burnt in a rotary tubular kiln from calcined raw cement meal is thrown off from the kiln discharge end onto a cooler, as a rule onto the cooling grate of a grate cooler, is distributed on this and is moved by suitable conveying means in the longitudinal direction to the cooler discharge end, cooling air flows passing through the cooling grate and hot bulk material layer essentially from the bottom upward. The known grate cooler types are explained briefly below.
In a push-type grate cooler, as seen in the conveying direction, fixed grate plate rows alternate with movable grate plate rows which can move back and forth and all grate plates are provided with cooling air ports, cooling air flowing through them essentially from the bottom upward, and, due to the jointly oscillating movement of all the movable grate plate rows, the hot material to be cooled is transported in pushes and is at the same time cooled. As an alternative to such a push-type grate cooler, for example, EP-B-1 021 692 discloses a grate cooler type in which the cooling grate through which cooling air flows is not moved, but, instead, is stationary, a plurality of rows of adjacent beam-shaped pushing elements movable back-and-forth being arranged above the stationary grate surface and being moved between a forward-stroke position in the direction of transport of the material to be cooled and a reverse-stroke position, so that, owing to the movement of these pushing elements back-and-forth in a material bed to be cooled, the material is likewise successively moved from the start of the cooler to the end of the cooler and is at the same time cooled.
In grate coolers of this type, unequal distributions in the hot bulk material bed in terms of the bulk material bed height, clinker grain size, temperature profile, etc. cannot always be avoided, thus resulting in uneven cooling. This is because, in cooling grate regions having a greater bulk material bed height, the flow resistance for the cooling air rises, the flow velocity falls and less cooling air is conducted through the bulk material bed, and, conversely, in cooling grate regions with a low bulk material bed height, the flow resistance for the cooling air falls, the flow velocity of the latter and the risk of an inrush of air increase, and too high a cooling air quantity is conducted precisely through those bulk material bed regions which would require the lowest cooling air quantity.
It is therefore known (EP-B-0 848 646), in a grate cooler for the cooling of hot bulk material, such as cement clinker, to regulate the respective cooling air quantity automatically in the cooling air inflows below the cooling grate in each case such that, with an incipient rise in the cooling air throughflow quantity caused by a decreasing bed height of the material to be cooled and a falling flow resistance, the clear cross-sectional area of the respective cooling air inflow lines is reduced, and vice versa, in order thereby to compensate a changing pressure drop across the bed of material to be cooled, so that the respective cooling air quantity is no longer dependent on the respective pressure loss or flow resistance of the cooling air in the respective zone of the bed of material to be cooled. In this case, the known mechanical cooling air throughflow quantity flow regulator operates with a weight-loaded pendulum flap with a horizontally lying pivot axis, the pendulum flap automatically throttling the respective cooling air inflow to a greater or lesser extent according to the prevailing pressure conditions and flow conditions. If the known cooling air regulator, which operates with a pivoting lever weight actuated purely by gravity and having inflow bodies, were arranged below the cooling grate in the cooling air inflows of cooling grate zones which are not stationary, but which, instead, are moved back-and-forth, together with regulators, in the case of a push-type grate cooler for the purpose of transporting the bulk material, then the automatic regulation of the regulator would be disturbed by the back-and-forth shaking movement and the regulation result would thereby be falsified.
WO-02/06748 also discloses, in a bulk material grate cooler, a cooling air regulator, in which a round stationary segmental disk provided with passage ports is arranged below the grate in the cooling air supply line and a vane disk held rotationally movably on a shaft is arranged above said segmental disk, said vane disk rotating as a function of the flow velocity of the cooling air and at the same time automatically varying the clear flow cross section of the segmental disk in such a way that, in the case of a rise in the flow velocity, the vane disk rotates counter to a spring force and the flow cross section is reduced, and vice versa. Even this automatically operating cooling air regulator does not rule out the risk that the functioning of the regulator is disturbed by the pulsating pendulum movement of the cooling grate zones which are movable back-and-forth.
Moreover, pneumatically controlled peristaltic valves as shut-off members are known in line with the conveyance of wear-inducing media, such as sludges and other suspensions containing solids. However, the problem of the conveyance of suspensions containing solids does not arise in a bulk material grate cooler.