GB1379934A - Grinding plants - Google Patents

Abstract

1379934 Tube mills, grinding cement F L SMIDTH & CO AS 15 Oct 1973 [4 Dec 1972] 55901/72 Heading B2A A grinding plant comprises cooling water injection equipment 23, Fig. 1, and a ventilating air supply with an electrostatic precipitator 12. On starting the plant, the flow rate of air is controlled in dependendce of cooling water flow rate, the injection of water and hence increase of air flow being delayed by a throttle damper 17 until it is necessitated by the increase of temperature (as sensed, e.g. by a member 24) within the mill or of the ground product delivered from the mill. As described, the plant comprises a feed hopper or hoppers 7, a weighing feeder or feeders 6, an inlet box 2 and outlet box 4 for the mill 7. Ground material is discharged via a pipe 8 and a screw conveyor 9. Fines separated by the precipitator 12 are discharged to the screw conveyor by pipe 15. Start-up follows the sequence of Fig. 2, with the precipitator voltage increased successively in dependence on flash over frequency which depends on cooling water flow. Temperature measurements may be taken at various locations and water injection may be controlled continuously or intermittently. Air volume may be controlled by a variable speed fan. Rapping frequency of the precipitator may also be controlled and the precipitator may be maintained in operation for a time after the mill is stopped. An auxiliary dedusting unit may be connected to a branch pipe connected to a point between the mill and the precipitator.