Submersible pumping station & Smart technology

Scope of works:

•  Replace current pumps with equivalent Flygt N-type, fitted with screened cable for VSD use.
• Replace existing air relief lines with black MDPE pipe.
• Replace pump control panels and remove from the confined space.  Reposition on suitable structure within the access area.
• Retain existing level control equipment but reposition main unit out of confined space and alongside pump control equipment.
• Replace all valves and rising main pipework to discharge point.
•  Install in-line magnetic flow meter on common discharge pipe and mount display alongside controls.
•  Replace lighting with suitable LED equivalent, battery backed emergency type.
•  Replace sump pump and connect to fixed transformer (110v) outside confined space.
• Replace sump pump pipework (black MDPE) 9) Possible full connection to HEART (SCADA)

Considerations:

• Confined Space conditions
• Unable to isolate the sump from continuous ingress
• Enabling works
• Continued two pump operation

There was nothing to be done to the actual structure of the station, merely the equipment within it.  The proposed equipment would be the following:

• Pumps: Flygt 3102 N-type
• Controls: Flygt SmartRun with central control unit
• Level sensor: Milltronics Hydroranger (existing)
• Valves: All isolation valves to be resilient seat gate type.  Non-returns to be swing type with weight arm.
• Flow meter: Xylem Magflux with remote display mounted outside of confined space. 
• Sump Pump: Lowara DOC3 or equivalent
• Control Philosophy

The use of the SmartRun units allows the pumps to look for the optimum energy efficiency point and will turn the station into a fully reactive operation.  Rather than just turn on and off at fixed points, the pumps will vary their speed to adjust to the inflow, optimising power consumption but, importantly reducing the number of starts.  The units also have algorithms for the self-cleaning of the sump and pipe, as well as removing blockages from the pumps.  

The SmartRun units come equipped ready to talk via the industrial MODBUS protocol, and the central control unit also allows for the connection of direct hardwired I/O signals.  Our preference would be to use MODBUS as this is far cleaner in terms of cabling and allows a greater number of signals

The existing drywell control, pump and pipework system was old and continually breaking down. The control panel had been mounted within the drywell area which is classified as a confined space.Access to the panel was always problematic and simple repairs were complicated because of the confined space entry.

Axflow GB  were tasked with providing a solution whilst refurbishing the pumps, pipework and valves and updating the control system whilst utilising the existing ultrasonic level system.

Before works could start we had to devise a step program that would allow us to keep one pump operational at all times with the capability of reconnecting and running the second pump if required. To do this we started by completing the enabling works which consisted of:

• Draining the sump and maintaining the ingress using a vacuum tanker
• Replacing both the suction valves into the drywell
• Disconnecting and removing the right hand pipework at high level
• Connect a stud converter onto the remaining high level flange connection 
• Providing a flexible hose with flanges on each end that can be connected to existing flanges as required.

With the enabling works done we were free to work on the system replacing one leg at a time always ensuring that we could complete each stage of the works whilst maintaining the level in the sump.

Whilst the pumps and pipework were being replaced our electricians were able to install the new Xylem Smartrun controllers and alarm panel in the cupboard area above the sump.

Once we had one leg completed and the new controllers wired in we were then able to complete the second leg of the pipework incorporating the new Magflux flow meter. The Smartrun controllers and Magflux unit were configured and the system commissioned.