Canadian Finishing & Coatings Manufacturing - Sept/Oct '23 - 32

PLATING AND ANODIZING: PUMPS AND FILTERS
FOR ENERGY SAVINGS
PROCESS CONTROLS
BY JOSEPH WARRENDER
nitiatives to conserve energy are more prevalent today
than in the past. Power consuming process equipment
in electroplating and metal finishing processes
in continuous operation are significant recurring
expenses. Reducing power usage lessens the load on power
grids while improving bottom line profits.
I
Pump Speed and Process Control
The majority of systems involve extremely low head
conditions, circulating solution with a horizontal tank.
Assuming proper piping system sizing, the primary head
restriction is the filtration system. Therefore, properly sized
filters and those with optimized flow characteristics reduce
the need for pump head pressure. Pump power consumption,
referenced on HP curves, diminishes cubically at reduced
speeds. Operating at excessive speeds often requires throttling
valves that expend energy and change the system curve that
hampers turnover flow. Trimming of impellers significantly
reduces pump efficiency due to the excessive internal volute
recirculation. Full size impellers avoid " hydraulic slippage "
but will require a VFD controller to avoid runout cavitation
from insufficient head.
Less Complex or invasive Initiatives
Install full size impellers and replace worn components with
full impeller trim sizes and operate at lower speeds with
VFD's to save energy. For an estimated energy savings, here
is a comparison of two pumps with different impeller sizes:
ANSI 3x2x6 - 15 HP pump with a full size 7-inch impeller at
50 Hz - 2900 RPM versus a trimmed 6.125-inch impeller at
60 Hz - 3500 RPM
* Target Flow & Head: 300 GPM @ 95' TDH / 47 PSID w/
1.15 S.G. Solution
* 3 HP reduction = $944.00 per year (per pump)
* This comparison is based on $315.00 per horsepower @
0.07 cents per kwh, 460V, with 250 days of production,
three shifts per day
When determining " probability factors' for maintaining
bath purity, required turnover rates combined with filter
efficiency ratings are primary factors. Production capacity
(e.g., # of bars per hour) and the particular chemistry
sensitivities are other issues.
32
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Pumped Flow Eductor Agitation
Eductor nozzles use the Venturi principle to amplify and
direct solution flow from the pump to the required area of the
tank. For 1 GPM of solution pumped through the eductor at
the required pressure, the discharge flow from the nozzle will
be up to 5 GPM. In simple terms a very high tank turnover rate
of solution can be achieved from smaller capacity pumps. The
solution can be directed easily within the tank with strategic
positioning of the nozzles.
More Complex Initiatives
Eductor Energy Savings
Air agitation inhibits uniform circulation. Accelerated heat
and chemical losses are released to the atmosphere. As
the air bubbles explode latent heat leaves the tank thereby
increasing the energy requirements to maintain process
temperature. Due to the explosion of air bubbles on the
surface of the solution, foam and noxious chemical fumes
are released which create an unpleasant and potentially
dangerous working environment as well as increasing the
need for vapour recovery systems. Air is non-conductive,
reducing the efficiency of the electrolyte. Brightener usage
is increased through oxidation. Oil and/or foreign bodies can
contaminate plating solutions. This type of agitation limits
the speed at which the racks can move, and the distance the
cathode moves requires added length.
Bath Air Agitated
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Canadian Finishing & Coatings Manufacturing - Sept/Oct '23

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