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1. WO1997027403 - IMPROVEMENTS IN AN UNLOADING PUMP WHICH IS SUBMERSIBLE IN THE CARGO OF A SHIP'S CARGO TANK

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[ EN ]

Patent Claims

1. An unloading pump arrangement, which is
submersible in the cargo of a ship's cargo tank (10a) and which has a pump inlet (13) arranged in or by a well (12) at the bottom (11) of the tank (10a) , where the pump arrangement (14) comprises a main pump (14a) and an auxiliary pump (30, 30', 30") which is drive connected with the impeller (15) of the main pump (14a) and which has a lower inlet end (35) arranged at a level between the bottom of the well (12) and the under side of the blades (15c) of the impeller (15) and an upper discharge end at a level above the under side of the blades (15c) of the main pump (14a) , and where the unloading pump has a discharge pipe (26) to a delivery location via deck (lOd) of the ship, characterised in that the auxiliary pump
(30, 30' , 30' ' ) , which has the form of a part conical sleeve portion or bell portion, has the maximum radial internal and external dimensions at the upper discharge end (at 38) of the auxiliary pump (30,30'30") and the minimum radial internal and external dimensions at the lower inlet end (35) of the auxiliary pump (30, 30 ' , 30' ' ) , and
that the internal flow passage (39) of the auxiliary pump (30, 30', 30") comprises an upper discharge chamber (38) and a number of outlet openings (40,40"), which empty directly out from the periphery of the discharge chamber (38) at the height of the flow-through passage (41) .
2. Arrangement in accordance with claim 1,
characterised in that the internal flow passage (39) of the auxiliary pump (30, 30' , 30' ' ) has an increasing cross- sectional area between the lower inlet (35) and the upper outlet (at 38) , the ratio between diameter D2 at the outlet (at 38) and diameter Dl at the inlet being greater than 1, that is to say D2/D1 > 1.

3. Arrangement in accordance with claim 1 and 2 , characterised in that the external guide face (36) of the auxiliary pump (30, 30 ',30") has a flow-increasing
peripheral dimension.
4. Arrangement in accordance with one of the claims 1-3, characterised in that the outlet openings (40,40") empty out into the flow-through duct (41) of the main impeller (15) at a level with blades (15c) of the main impeller (15) .
5. Arrangement in accordance with one of the claims 1-4, characterised in that the auxiliary pump (30") is formed from a sleeve of relatively thin-walled material converging from below obliquely upwards and outwards, and that the sleeve is secured via its upper peripheral edge portion (30a") at a guide portion (36a", 36b") in impeller (15) of the main pump,
the outlet openings (40") being formed just by, that is to say immediately below the fastening of the sleeve to the impeller (15) of the main pump.
6. Arrangement in accordance with claim 5,
characterised in that the upper peripheral edge portion (30a") of the sleeve is received in an annular cavity (36") in an inner guide portion (36a", 36b") curved obliquely upwards and outwards in the impeller (15) of the main pump,
the peripheral edge portion (30a' ' ) being flush with an upper, inner guide portion (36a") in the impeller (15) of the main pump.
7. Arrangement in accordance with claim 5 or 6, characterised in that outlet openings (40") of the sleeve have the radially outermost portion of the upper opening edge (40a") extending obliquely upwards and outwards flush with the upper, inner guide portion (36a") in the impeller (15) of the main pump and the radially innermost portion of the upper opening edge extending obliquely upwards and outwards flush with a lower, inner guide portion (36b") in the impeller (15) of the main pump, the outlet openings (40") of the sleeve being preferably formed from obliquely upwardly and outwardly directed bores .