Multistage slurry pump

1. A multi-stage partial emissions pump comprising a first stage impeller, a coaxially mounted final stage impeller, a first stage inlet liner, a first stage casing liner, one or more first stage discharge outlets, a final stage casing liner, a cover, one or more final stage discharge outlets, an interstage delivery channel liner, for each of the first stage discharge outlets an associated delivery channel formed in the interstage liner, and an outer pressure shell, wherein:

the first stage impeller is enclosed in a first stage cavity formed between the first stage inlet liner and the first stage casing liner, the first stage inlet liner being in fluid communication with a first stage inlet;

the final stage impeller is enclosed in a final stage cavity formed between the final stage casing liner and the cover, the final stage casing liner being in fluid communication with a final stage inlet;

the first and final stage discharge outlets are sized so as to restrict outflows of fluids from the first and final stage cavities during each revolution of the first and final stage impellers to be small percentages of volumes of the first and final stage cavities, respectively;

each of the first stage outlets includes a nozzle for discharging fluid into a straight conical diffuser formed in the first stage casing liner and penetrating an outer surface of the first stage casing liner;

each of the delivery channels is positioned to receive the fluid discharged from the conical diffuser of the associated first stage outlet and convey the fluid to the final stage inlet; and

the sum of the cross sectional areas of all said delivery channels taken on a radial plane intersecting the delivery channels is less than the sum of cross sectional areas of all non-channel areas within all boundaries of the delivery channels on said plane.

2. The pump according to claim 1 , whereby the surfaces of the pressure shell are isolated from high velocity flows by said liners.

3. A multi-stage partial emissions pump comprising a first stage impeller, one or more coaxially mounted intermediate stage impellers, a coaxially mounted final stage impeller, a first stage inlet liner, a first stage casing liner, one or more first stage discharge outlets, one or more intermediate stage inlet liners, one or more intermediate stage casing liners each with one or more intermediate stage discharge outlets, a final stage casing liner, a cover, one or more final stage discharge outlets, a plurality of interstage delivery channel liners, for each of the first stage and intermediate stage outlets an associated delivery channel formed in one of the interstage liners, and an outer pressure shell, wherein:

each of the impellers except the final stage impeller is enclosed in a cavity formed between one of the inlet liners and one of the casing liners, the inlet liner being in fluid communication with an inlet of the cavity;

the final stage impeller is enclosed in a cavity formed between the final stage casing liner and the cover, the final stage casing liner being in fluid communication with an inlet of the final stage cavity;

for each of the cavities, the discharge outlets are sized so as to restrict an outflow of fluids from the cavity to be a small percentage of a volume of the cavity during each revolution of the impeller enclosed in the cavity;

each of the discharge outlets includes a nozzle for discharging fluid into a straight conical diffuser formed in one of the casing liners and penetrating an outer surface of the casing liner;

each of the delivery channels is positioned to receive the fluid discharged from the conical diffuser of the associated discharge outlet and convey the fluid to the inlet of the next stage; and

the sum of the cross sectional areas of all said delivery channels taken on a radial plane intersecting the delivery channels is less than the sum of cross sectional areas of all non-channel areas within all boundaries of the delivery channels on said plane.

4. The pump according to claim 3 , whereby the surfaces of the pressure shell are isolated from high velocity flows by said liners.

5. A multi-stage partial emissions pump comprising a first stage impeller, a coaxially mounted final stage impeller, a first stage inlet liner, a first stage casing liner, one or more first stage discharge outlets, a final stage casing liner, a cover, one or more final stage discharge outlets, for each of the first stage discharge outlets an associated delivery channel formed in the final stage casing liner, and an outer pressure shell, wherein:

the first stage impeller is enclosed in a first stage cavity formed between the first stage inlet liner and the first stage casing liner, the first stage inlet liner being in fluid communication with a first stage inlet;

the final stage impeller is enclosed in a final stage cavity formed between the final stage casing liner and the cover, the final stage casing liner being in fluid communication with a final stage inlet;

the first and final stage discharge outlets are sized so as to restrict outflows of fluids from the first and final stage cavities during each revolution of the first and final stage impellers to be small percentages of volumes of the first and final stage cavities, respectively;

each of the first stage outlets includes a nozzle for discharging fluid into a straight conical diffuser formed in the first stage casing liner and penetrating an outer surface of the first stage casing liner;

each of the delivery channels is positioned to receive the fluid discharged from the conical diffuser of the associated first stage outlet and convey the fluid to the final stage inlet; and

the sum of the cross sectional areas of all said delivery channels taken on a radial plane intersecting the delivery channels is less than the sum of cross sectional areas of all non-channel areas within all boundaries of the delivery channels on said plane.

6. The pump according to claim 5 , whereby the surfaces of the pressure shell are isolated from high velocity flows by said liners.

7. A multi-stage partial emissions pump comprising a first stage impeller, one or more coaxially mounted intermediate stage impellers, a coaxially mounted final stage impeller, a first stage inlet liner, a first stage casing liner, one or more first stage discharge outlets, one or more intermediate stage inlet liners, one or more intermediate stage casing liners each with one or more intermediate stage discharge outlets, a final stage casing liner, a cover, one or more final stage discharge outlets, for each of the first stage and intermediate stage outlets an associated delivery channel formed in one of the inlet liners, and an outer pressure shell, wherein

each of the impellers except the final stage impeller is enclosed in a cavity formed between one of the inlet liners and one of the casing liners, the inlet liner being in fluid communication with an inlet of the cavity;

the final stage impeller is enclosed in a cavity formed between the final stage casing liner and the cover, the final stage casing liner being in fluid communication with an inlet of the final stage cavity;

for each of the cavities, the discharge outlets are sized so as to restrict an outflow of fluids from the cavity to be a small percentage of a volume of the cavity during each revolution of the impeller enclosed in the cavity;

each of the discharge outlets includes a nozzle for discharging fluid into a straight conical diffuser formed in one of the casing liners and penetrating an outer surface of the casing liner;

each of the delivery channels is positioned to receive the fluid discharged from the conical diffuser of the associated discharge outlet and convey the fluid to the inlet of the next stage; and

the sum of the cross sectional areas of all said delivery channels taken on a radial plane intersecting the delivery channels is less than the sum of cross sectional areas of all non-channel areas on said plane within all boundaries of said delivery channels.

8. The pump according to claim 7 , whereby the surfaces of the pressure shell are isolated from high velocity flows by said liners.