Method and suction dredging installation for conveying dredging spoil

Claim 2

A suction dredging assembly comprising, in combination; a suction pipe having an open lower end adapted to be projected into a body of underwater material which is to be dredged; supporting structure including means for controlling the position of said lower end of the suction pipe; a pump on said supporting structure having an inlet connected to said suction pipe for withdrawing a suspension of said material therethrough, and having an outlet for discharging such suspension, said pump operating to produce a predetermined pressure difference between its outlet and its inlet when at an optimum pumping efficiency; a pressure difference pick-up connected between said outlet and said inlet of the pump and having an output which increases when the pressure difference between said inlet and said outlet deviates to exceed said predetermined pressure difference and vice versa; and means for enabling control of said suction dredging assembly in response to said deviations to maintain said pump operating at or near said optimum pumping efficiency.

Claim 3

A suction dredging assembly comprising, in combination; a suction pipe having an open lower end adapted to be projected into a body of underwater material which is to be dredged; supporting structure including means for controlling the position of said lower end of the suction pipe; a pump on said supporting structure having an inlet connected to said suction pipe for withdrawing a suspension of said material therethrough, and having an outlet for discharging such suspension, said pump operating to produce a predetermined pressure difference between its outlet and its inlet when at an optimum pumping efficiency; a pressure difference pick-up connected between said outlet and said inlet of the pump and having an output proportional to the pressure difference between such outlet and inlet so as to determine both positive and negative pressure difference deviations with respect to said predetermined pressure difference; and means for enabling control of said suction pipe in response to said deviations to maintain said pump operating at or near said optimum pumping efficiency.

Claim 4

A suction dredging assembly comprising, in combination; a suction pipe having an open lower end adapted to be projected into a body of underwater material which is to be dredged; supporting structure including means for controlling the position of said lower end of the suction pipe; a pump on said supporting structure having an inlet connected to said suction pipe for withdrawing a suspension of said material therethrough, and having an outlet for discharging such suspension, said pump operating to produce a predetermined pressure difference between its outlet and its inlet when at an optimum pumping efficiency; a pressure difference pick-up connected between said outlet and said inlet of the pump and having an output proportional to the pressure difference between such outlet and inlet so as to determine both positive and negative pressure difference deviations with respect to said predetermined pressure difference; and means for enabling control of said suction pipe in response to said deviations to maintain said pump operating at or near said optimum pumping efficiency.

Claim 5

A suction dredging assembly as defined in claim 2 wherein said means includes a pressure difference indicator for enabling an operator to control the position of said lower end of the suction pipe.

Claim 6

The suction dredging assembly as defined in claim 2 wherein said means includes differentiator means for differentiating said output of the pressure difference pick-up with respet to time to produce a signal indicative of the rate of pressure difference change.

Claim 7

The suction dredging assembly as defined in claim 4 wherein said means also includes an indicator connected to the signal of said differentiator means.

Claim 8

A suction dredging assembly as defined in claim 4 wherein said means also includes a signaling device connected to the signal of said differentiator means and responsive to a predetermined value of pressure difference rate of change.

Claim 9

A suction dredging assembly as defined in claim 4 wherein said means also includes a regulating member connected to said differentiator means for regulating said suspension in said suction pipe.

Claim 10

A suction dredging assembly as defined in claim 2 wherein said means includes a signaling device connected to said pick-up and responsive to a predetermined maximum positive deviation in pressure difference across said pump.

Claim 11

A suction dredging assembly as defined in claim 2 wherein said means includes a signaling device connected to said pick-up and responsive to a predetermined maximum negative deviation in pressure difference across said pump.

Claim 12

A suction dredging assembly as defined in claim 2 wherein said means includes a regulating member connected to said pick-up for regulating the suspension in said suction pipe.

Claim 15

A method according to claim 11 including the step of measuring the time rate of change of the pressure difference, and wherein the controlling of step (c) is in accord with such time rate of change.