Monday, December 10, 2012

Little Bennett Pump Station Upgrade

Did you have any idea an irrigation pumping system was so complex?  

Little Bennett has just upgraded from an antiquated, energy-wasting system to a new state of the art control system that will provide dramatically improved and safer performance, use less electricity, and give the superintendent the ability to see what is happening at the pump station from anywhere there is internet access!

Golfers may occasionally wonder what it takes to irrigate a golf course.  An 18-hole golf course can cover anywhere from 100-300 acres of land and requires miles and miles of pipe to deliver water.  At least 2 to 4 pumps are required to keep pressure and move water across the golf course.  These pumps can provide up to 2500 gallons per minute(GPM).  Main pumps are powered by 50-75 hp motors and most courses utilize a small pump called either a jockey or pressure maintenance pump.  These smaller pumps are powered by 5-25 hp motors.  The small pumps are there to maintain pressure on the irrigation lines and for low flow operations.  An example of low flow would be 1 or 2 irrigation heads running or multiple hoses being used.  Pump station output is usually 10 times the horsepower of all your motors combined in GPM. 

Little Bennett runs two 75hp main pumps and one 25hp jockey pump.  The pumps are 20 feet long and are located in a wet well inside the pump house.  The pumps draw water for the golf course from the irrigation pond on hole #10.  The station requires 460 volt 3-phase incoming power.  The system was designed with a pressure tank and regulating valve to deliver 1800 GPM at 125 psi.  There's a panel that controls motor/pump starts and stops and is run by a programmable logic controller(PLC).  The PLC controls the station by inputs that regulate when pumps turn on and off based on pressure and flow.  The tank is designed to build pressure on the upstream(between the pumps and the valve) side.  When pressure drops on the downstream(between the valve and outflow pipe to the golf course) side of the regulating valve(e.g., heads running on the golf course), the valve opens and allows pressure to equalize.  When pressure in the tank becomes equal to outflow pressure the valve opens completely and allows water to flow freely.  The PLC calls for a pump to turn on and it comes on at full speed for however long it takes to build pressure back up and sustain flow.  This is what is called a fixed-speed system and this is very energy inefficient. 

old pump station control cabinet with PLC
old pressure tank
We decided that it was time to upgrade our control capability and take advantage of new technology.  The jockey pump and regulating valve were worn out and not functioning well and there was concern of interior deterioration of the pressure tank.  We've had to adjust our effective output down to 1000 GPM to prevent the system from shutting down.  The pump station was faulting more often than it would run successfully due to high and low pressure situations and component failure inside the cabinet.  The control cabinet was also becoming obsolete and components were either very expensive or impossible to find. 

The best time of year to do any work to a pump station is late fall/early winter when the need for irrigation is minimal.  We knew that we would have no capability to pump water for at least 7 days once work was started.  Contractors were selected for this specialized work and work began the week after Thanksgiving.

The work to be done included demolishing the cabinet, valve, and tank.  It also included removing and replacing the jockey pump and motor.  A new control cabinet would be put in place and a new manifold and section of pipe would replace the tank and valve.  The new cabinet would contain two variable frequency drives(VFD) that control the motors and pumps.  The VFD regulates the amount of power supplied to the motor and only allows the pumps to turn at the speed required to deliver the amount of water that is needed.  This is very energy efficient.  Radio receivers would be installed at the pump house and maintenance shop so that we could view real time pump performance.  This would also allow the greens staff to view the pump station PLC screen at any time and from anywhere using remote log-in to the irrigation computer.  In the future the radio communication will allow us to integrate the pump with the irrigation control computer for truly optimized pump performance.

Here are the main project phases in pictures:
Demolition of the old tank
Demolition of valve and control cabinet
Ready for manifold
New manifold going in
Manifold attached and skid primed

Carefully moving the new control cabinet in the door

New cabinet in place on the skid

Crane setting up to remove old jockey pump and motor
Pump coming out through opening in the roof

New pump going in

New pump installed and skid freshly painted

new, state-of-the-art, control cabinet PLC interface

Installation of radio receiver at maintenance building

With the work now completed, we expect to have a much more efficient pumping system.  We should realize a significant reduction in energy usage and associated cost.  Since we have a better functioning station, we should be able to effectively run at a higher GPM than in the past.  This will shorten the amount of time that it takes to run irrigation programs.  High and low pressure faults will mostly be eliminated with the new control system.  Dangerous pressure swings will also be eliminated and that should lower the number of pipe breaks we face every year.  This is a crucial infrastructure upgrade that benefits the golf course but is not something our golfers would normally see!

Matt Burton
Golf Course Superintendent
Little Bennett Golf Course

No comments: