Transcript EDUCTOR AGITATION: A NICKEL ELECTROPLATING …

EDUCTOR AGITATION FOR
HEAVY NICKEL DEPOSITION:
A CASE STUDY.
DAVID GABE
LOUGHBOROUGH UNIVERSITY
and
CLIVE PORTER
Formerly DOWDING and MILLS LTD.
A sponsored research project
for the MSc course in Surface
Engineering.
Nottingham – Loughborough
– Hull - Sheffield Hallam
Universities
MANAGEMENT OBJECTIVES
• Focus on refurbished marine
engine components
• To improve the process throughput
and production rates
• To improve the product quality
PURPOSE OF PROJECT
• To obtain data to justify the installation
of eductor agitation
• To improve plant instrumentation and to
monitor the enhanced process
• To establish criteria to measure the
degree of process enhancement
PRESENTATION
CONTENTS
• Design of an Eductor system
• Some performance parameters
• Bonuses
DESIGN OF EDUCTOR
SYSTEM
• Tank and pump sizing
• Eductor numbers and placement
• System costing
• Commissioning
• Benchmarking
• Optimization
• Monitoring
INSTALLATION
• 6000l tank having air agitation
• Total agitation flow of 4000l/min
• Pumped vol. of 800l/min
• Pump size; 2.2kW three-phase
• 20 x 3/8in eductors, 5 each side
• Eductors mounted in swivel tubes
• System costing (2002): £2509
TANK PREPARATION
• Both air and eductor agitation
were retained for comparisons
• Thorough cleaning vital! Any
residual sludge is highly abrasive.
• Additional ammeters needed for
independent current monitoring
BENCHMARKING
• Air agitation alone
• Eductors alone
• Eductors at several swivel angles
• Use of test panels jigged at various
positions in the tank
• Test panels thoroughly thickness
tested over whole surface
PATTERN OF AGITATION
• Agitation observed using air
bubble entrainment
• The installation was modelled
before use using clean water and
good lighting
• Each bank of eductors was
adjustable for angle of jetting
DEPOSITION RATES
(Watts nickel)
• Air agitation
3.709g/hr
• Eductor agitation (30º) 4.527*
• Optimized eductors
5.054*
* Increases of 22% and 36.3%
respectively
THICKNESS VARIANCE
Agitation Time for 0.2mm
type
Air
22 hr
Eductors
8 hr 48 min
Optimized
eductors
6 hr 17 min
Corner excess,
mm.
0.8
0.24*
0.0575*
*Waste improvements of 70% and 92%
respectively
THICKNESS
DISTRIBUTIONS
Criterion Air
Eductors
Wt. gain(g):
20.4
24.9
Thickness(mm):
Corners 0.25
0.275
Centre
0.05
0.125
Variance 0.2
0.15
Optimized
eductor
27.8
0.225
0.175
0.075
EDUCTOR ADVANTAGES
(Gabe, Ward* and Porter** using Cu* and Ni**)
• Agitation Enhancement over air: 710x
• Deposition rate improvement:
36%
• Shorter process times: 71%
• Reduced thickness variability: 92%
EDUCTOR BONUSES
• Zero fume emission
• Reduced power usage in tank (ie. no
insulative air bubbles) worth 1-2V or
~25% per tank
• Reduction in sludge production (ie no
oxidising air) and condensate
• Reduced additive consumption
• Saving of heating energy with no fume
losses: 10-20%
AIRBORNE EMISSIONS*
• AIR
• EDUCTORS
0.5-1.0mg nickel per
m3 air volume
0
• *Draeger tube emission
measurements
EDUCTORS AND PROCESS
FUME
• Process fume is substantially created by the
gas phase and its release at the surface
• Affected by surfactants and mist suppressants
• The fume consists of a solvent/solute mist
• Use of Eductors eliminates 95% of the mist
• Only public domain data is for nickel
electroplating (see Porter and Gabe, Plating &
SF 2005).
• Ni content of Eductor fume was practically
zero.
• Fume carries heat; heat losses can be reduced
PROCESS SLUDGE
• Process sludge is produced by oxidation
of dissolved metal and organic
additives, and precipitation.
• Agitative air is the oxidation medium
and eductors eliminate this source of
sludge.
• Anodic oxidation of additives is
primarily an anode material problem.
Choice of anode can be an issue.
CONCLUSIONS
• Increased rates of production and
improved film thickness distribution
• Saving of power usage to offset
increased pumping costs
• A reduction in oxidation and sludge
formation; reduced fume and heat
losses
• Technology also useful for cleaning,
pickling, etching, rinsing etc.