• Author / Uploaded
• Carlos Diaz

Citation preview

SRH/SRC Series Elastomer-lined horizontal centrifugal pumps for abrasive/corrosive slurries Wet Gland and Dry Gland Configuration

Excellent Engineering Solutions

SRH/SRC centrifugal pumps for abrasive/corrosive slurries

SRH/SRC slurry pumps Weir Minerals as a world leader in centrifugal slurry pump design continues to invest in research and technology. As a result a generation of slurry pumps, designated SRH/SRC, has been designed to significantly reduce the operating costs of pumping abrasive/corrosive slurries. This generation of elastomer-lined pumps has been specifically developed to provide the lowest possible operating cost to the end user. This is made possible by incorporating the best features established from field proven designs ensuring ease of maintenance on site. By combining traditional strengths, ruggedness and dependability with advanced hydraulics, these pumps offer enhanced efficiency resulting in increased wearlife of components such as wearing liners and impellers. The advanced hydraulics utilises a unique patented volute design

which reduces destructive turbulence thus further reducing the overall power consumption – the largest expense in total operating cost.

SRH “Wet Gland” or SRC ”Dry Gland” Configurations SRH models deliver maximum hydraulic efficiency in applications where minor process dilution is permissible from wet glands. SRC models incorporate a unique two-stage dynamic expeller seal which eliminates seal water and reticulation while effectively sealing against suction heads of up to 12 metres. This sealing arrangement is completely protected by abrasion- and/or corrosion-resistant elastomer linings.

Design features – reduced operating costs

Feature

Benefit

High efficiency design

Reduced power consumption

Advanced hydraulics • Reduced turbulence – unique volute design. • Less recirculation and internal head loss • Superior suction characteristics – lower NPSH required.

Extended parts life • Less concentrated wear on liners and impellers. • Lower impeller peripheral speeds. • Less likely to cavitate.

Thicker Liners Absorb impact from large particles.

Longer wear life Greater resistance to cuts and crushing damage.

Reinforced non-collapsible liners

Reduced erratic failures

Effective and reliable ”dry gland” capability Unique two-stage expeller design.

No gland seal water required - ”dry gland” No dilution or contamination of critical processes. Eliminates the need for costly seal water and reticulation.

Unique bearing arrangement Utilises both radial and axial bearings.

Maximum head capability More efficient, advanced hydraulics.

Casing pressure ratings to 3500 kPa Higher pressure ratings available.

High pressure applications

Fewer casing bolts and fasteners Full accessible eliminating hidden bolts.

Easily maintained Reduced maintenance downtime.

SRC Configuration “Dry gland” expeller seal Low sump level

Slurry

Principle of operation Typically with most centrifugal slurry pumps, the pressure at the gland increases as the sump level is increased or as the impeller rotational speed is increased to deliver additional hydraulic performance. To prevent leakage (and to prevent impregnating the gland packing with solids), gland service water is injected at a higher pressure to flush the slurry away from the packing.

Air Seal

Static h suction

SRC configured pumps incorporate a unique two-stage auxiliary expeller design. The two expellers operate in series in independent expeller chambers to increase the expeller head capability and pump the process liquid away from the gland while subject to higher suction pressure (i.e. sump levels).

Dual expeller

Normal sump level

The higher pressure developed by the centrifugal force generated by the two stages of expellers is balanced against the combination of the suction pressure and the pressure generated by the impeller to form an interface of air and liquid at the equilibrium point. The liquid, being denser, experiencing a larger response to centrifugal forces, creates a wall which the air is capable of penetrating. Consequently the air mixes with the liquid. Air under atmospheric pressure is permitted to enter through the gland packing and fill the void between the packing and expeller liquid interface. At a given impeller rotational speed the void will vary as the sump level varies as illustrated in the three examples.

Slurry

Air Seal

Static h suction

Dual expeller

During operation of the pump the only pressure existing at the gland is atmospheric… even at increased impeller rotational speeds. The suction head capability of the SRC has been plotted on a separate performance curve. By plotting the discharge rate and total head for the pump the suction head, expressed in maximum permissible height of the liquid above the centre line of the pump expeller, can be established thus eliminating uncertainty associated with the application of the dry gland dual expeller configuration.

High sump level

Slurry

Air Seal

Static

h suction

Dual expeller

Unique volute design channels flow pattern Volute geometry leaving the impeller and directs it to the discharge with minimum turbulence

SRH Wet gland gland service water inlet

19

4 3 5 2 1 6

8

9

7

10

11

19

12

18

17

16

15

14

13

SRC Dry gland

1

High pressure ratings

7

Stellited slip-fit shaft sleeve

15

Gland leakage drain (threaded)

2

Through-bolt flanges

8

Protective flinger/excluder

16

Accessible bolts

3

Non-collapsible reinforced liners

9

Lifting lugs

17

Anti-seize impeller thread

4

Thick field-replaceable liners

10

18

Dynamically balanced impeller

5

Unique two stage expeller • Eliminates costly seal water • Suction heads to 12 metres • Easily replaceable abrasion/corrosion resistant elastomer parts

Cartridge-type shaft/bearing assemble protected slide movement

19

11

Lubrication - grease or oil

12

Rigid cast pedestal

Advanced hydraulics • High efficiency • Reduced turbulence/recirculation • Superior suction characteristics

13

Protected impeller adjustment

14

Large diameter rigid shaft

6

Extended gland life • Minimum shaft deflection • Seal assembly piloted directly to pedestal • Unique bearing arrangement

Excellent Engineering Solutions