IAP Supplies new Vacumn Bowser Units to Royal Dockyard

During Sept 2007 Babcock Marine Energy Manager and Industrial Air Power Ltd, discussed the use of Jetvac units used at Devonport for cleaning out waste liquids onboard ships.

Devonport’s concern was the method used to create vacuum to the unit was a venturi fed by compressed air.

This method of creating a vacuum is grossly inefficient and with no control over the system, operatives can leave the equipment running indefinitely. Following our discussions, it was decided that a unit capable of similar performance to the Jetvac, however not reliant on compressed air was not available. Therefore in order to provide a unit for use at Devonport it would have to be a bespoke purpose build.

Devonport’s requirements included a 3000 ltr double skinned bunded vessel, an electrically driven method of generating a vacuum, and a control system to be agreed. IAP provided a vacuum pump and a 2000 ltr vertical receiver in order to carry out trials at 7 dock. The pump inlet was fed by a 2” pipe supplied by Babcock simulating the same set up procedure as was used for the Jet vac system; the outlet of the pump was connected to the vertical receiver.

Liquid was pumped from the dock bottom approximately 35 – 40 ft and was stored inside the vertical receiver, proving the general capability of the equipment selected. Further trials were carried out successfully and measurements were taken by devonport which were compared with energy costs and general performance of the Jetvac system.

Devonport Project Team estimated that the performance of the proposed electrically driven Vacuum Bowsers would be much greater than the existing Jetvac units and power consumption would be 50% less. At this stage it was decided that a trial unit should be developed incorporating a list of requirements from Babcock:-

  • Skid mount with fork truck lifting facility and eyelets for slinging by crane.
  • Double skinned (bunded) 3000 ltr vessel with float level control.
  • 11 Kw liquid ring vacuum pump with filtration protection

Control system offering:-

  • Liquid level full stop
  • Hours run
  • 4 hour cut out / reset
  • Hours run meter

Connections from top of vessel to include a 4” emptying connection with stainless steal ball valve complete with flange cover plate.

Operator’s platform with ladder and safety barriers.

A design company were commissioned by Industrial Air Power Ltd to provide assembly / fabrication drawings and specifications which were approved by Devonport prior to ordering the first unit on 28.11.2008.

On completion of the first unit it was delivered to Devonport site on 25.11.08, following delivery further trials were carried out,during which several small modifications were identified and recommended to be incorporated in any future further orders.

Babcock Marine Project Team carried out actual trials and comparison figures between the Vac Bowsers and original Jetvac units as follows.

Cost & Consumption

IAP Vacumn Bowser

Jet-Vac

Comments

Air Flow

0

157m3/hr

25951 l/min – No Change in Load on Jet Vac even when idle.

Air Flow

0

92.41 CFM

1 CFM = 1.699 m3/hr

Volume Per Hour

0

5,544.44 CFM

 

kWh per CFM

0

0.00315

 

kWh

0

17.46 kWh

 

Average Power

9.00 kW

0

As measured during trial, but will decrease slightly when off load.

Consumption per Hour

9 kWh

17.46kWh

 

Energy Cost to Run

£0.63

£1.22

 

Further to these results a further seven units were purchased on 24.3.2010 and were completed and delivered on time by Industrial Air Power Ltd.

All duties for this type of equipment are now carried out using the new equipment and both efficiency of operation and energy consumption are continuously benefiting Operators across the Dockyard.