Device for evaluating the quality of cake in intermittent filters

Claim 1

A device for controlling a required quality such as thickness, degree of washing and drying of filter cake in an intermediate filter during respective filtering, washing and drying operations which filter has a filter chamber with an inlet manifold through which sequentially passes slurry, wash liquid and drying air depending upon which respective one of said filtering, washing and drying operations is taking place, and a filtrate discharge outlet through which passes filtrate and discharge wash-liquid, said device comprising: a pair of thickness sensor means, one of which is mountable in said inlet manifold, the other in said filter chamber, said pair of thickness sensor means providing a first difference signal therebetween representative of the thickness of said cake during said filtering operation; a pair of washing sensor means, one of which is mountable in said inlet manifold, the other in said filtrate discharge outlet, said pair of washing sensor means providing a second difference signal therebetween representative of the degree of washing of said cake during said washing operation; a pair of drying sensor means, one of which is mountable in said manifold, the other in said filter chamber, said pair of drying sensor means providing a third difference signal therebetween representative of the degree of drying of said cake during said drying operation; measuring means sequentially connected to said pair of thickness sensor means, said pair of washing sensor means and said pair of drying sensor means, for sequentially measuring said first, second and third difference signals, said measuring means providing respective output signals thereof and determining when each of said respective output signals attain set values representative of said required quality of said cake; sequence switch means operatively associated with said measuring means and said determination means for sequentially selecting each of said filtering, washing and drying operAtions and corresponding respective ones of said sequential connections of said measuring means as each of said respective output signals attain said set values to thereby control said required quality of said filter cake.

Claim 2

A device for controlling a required quality such as thickness, degree of washing and drying of filter cake in an intermediate filter during respective filtering, washing and drying operations which filter has a filter chamber with an inlet manifold through which sequentially passes slurry, wash liquid and drying air depending upon which respective one of said filtering, washing and drying operations is taking place, and a filtrate discharge outlet through which passes filtrate and discharge wash-liquid, said device comprising: a pair of thickness sensor means, one of which is mountable in said inlet manifold, the other in said filter chamber, said pair of thickness sensor means providing a first difference signal therebetween representative of the thickness of said cake during said filtering operation; a pair of washing sensor means, one of which is mountable in said inlet manifold, the other in said filtrate discharge outlet, said pair of washing sensor means providing a second difference signal therebetween representative of the degree of washing of said cake during said washing operation; a pair of drying sensor means, one of which is mountable in said manifold, the other in said filter chamber, said pair of drying sensor means providing a third difference signal therebetween representative of the degree of drying of said cake during said drying operation; measuring means sequentially connected to said pair of thickness sensor means, said pair of washing sensor means and said pair of drying sensor means, for sequentially measuring said first, second and third difference signals, said measuring means providing respective output signals thereof and determining when each of said respective output signals attain set values representative of said required quality of said cake; sequence switch means operatively associated with said measuring means and said determination means for sequentially selecting each of said filtering, washing and drying operAtions and corresponding respective ones of said sequential connections of said measuring means as each of said respective output signals attain said set values to thereby control said required quality of said filter cake.