ultrasonic cleaning

Ultrasonic cleaning

One of the major applications of high power ultrasonicCommonly used frequencies between 20 KHz and 50KHz

.

Working principleCavitations• Conversion of electrical vibrations into

mechanical vibrations and to cause the bottom of the tank to vibrate resulting an intense agitation of the liquid molecules contained in the tank. Thus the violent disturbance in the liquid results in the formation of cavities or voids.

• The cavitations in the liquid medium is produced due to the propagation of ultrasonic waves.

• Due to the collapse of the cavitations, a tremendous amount of energy is released.

• These energies produce an intense local scrubbing action on the material, which is immersed in the cleaning liquid

Illustration of cavitations formation process

Cleaning medium

• Ideal cleaning medium should have low surface tension and low viscosity for increasing effect of cleaning

• Two types:

i) aqueous

-Used for removing common contaminants

ii) solvent (halogenated hydrocarbon)

-Used for removing solder flux, grease or heavy oil

Ultrasonic cleaning equipments

• Transducer• Tank• Generator

Transducer• Used to convert electrical

energy to mechanical vibration

• The transducer can be fixed in three ways:

i. Directly at the bottom of the tank

ii. Using transducer plateiii. Using submersible transducer• Piezoelectric ceramic crystals

commonly used as they can transmit 70% to 90% of applied energy to cleaning liquid

Magnetostrictive

• utilize the principle of magnetostriction in which certain materials expand and contract when placed in an alternating magnetic field.

• generally less efficient than their piezoelectric counterparts

Piezoelectric

• convert alternating electrical energy directly to mechanical energy through use of the piezoelectric effect in which certain materials change dimension when an electrical charge is applied to them.

• Electrical energy at the ultrasonic frequency is supplied to the transducer by the ultrasonic generator

Comparison Blue WaveMagnetostrictive

The CompetitionPiezoelectric

•Performance properties NEVER degrade •Silver-brazed transducers NEVER disbond •Metal to metal bond; MORE EFFICIENT energy conversion •Heavy duty (316L) diaphragms NEVER wear through (From Cavitation Erosion) •Heavier mass; NOT susceptible to variable loads •The ONLY Lifetime Guarantee in the industry!

•Performance properties DO degrade •Epoxied transducers DO disbond •Epoxy bond DAMPENS energy conversion •Light weight diaphragms DO wear through (From Cavitation Erosion) •Lighter mass; Susceptible to load variations •Not Even Close

tank• Console cleaning systems

integrate ultrasonic cleaning tank(s), rinse tank(s) and a dryer for batch cleaning.

• Systems can be automated through the use of a PLC controlled material handling system.

Console cleaning systems

• A wide range of options may be offered in custom designed systems

• Large scale installations or retrofitting of existing tanks in plating lines, etc., can be achieved through the use of modular immersible ultrasonic transducers.

• Ultrasonic generators are often housed in climate-controlled enclosures.

• .

Custom designed system

Generator• converts electrical energy from the line which is typically alternating current

at 50 or 60Hz to electrical energy at the ultrasonic frequency. • Current ultrasonic generators nearly all use solid state technology. • There have been several relatively recent innovations in ultrasonic

generator technology which may enhance the effectiveness of ultrasonic cleaning equipment. – square wave outputs, slowly or rapidly pulsing the ultrasonic energy on

and off and modulating – "sweeping" the frequency of the generator output around the central

operating frequency– adjusting a variety of output parameters to customize the ultrasonic

energy output for the task.

Procedure• The cleaning liquid either

aqueous or solvent is filled in the tank

• The transducer mounted at the bottom of the tank for generation of ultrasonic wave

• The vibrations are transferred into the liquid medium through the stainless steel tank (cavitations formation)

Automated ultrasonic cleaning system

• This system is designed to clean intricate metal hearing-aid components using a neutral-pH solution at 60ºC (140ºF) and three rinse stages at 70ºC (160ºF). Basket rotation (1 to 3 rpm) is used during each stage to ensure adequate cleaning and rinsing. The system computer controls all functions, including the hoist, and allows for storage of different process parameters for different types of parts.

Advantages• Enhanced cleaning speed for both aqueous and solvent

medium• Less cost• It occupies less space and reduces labour• It can be occupied in cleaning hazardous substances

without the contact of the workers• Environmentally pollution free• High safety with less complaints

Ultrasonics Speeds Cleaning by Dissolution

+ Cavitation and implosion as a result of ultrasonic activity displace and remove loosely held contaminants such as dust from surfaces. For this to be effective, it is necessary that the coupling medium be capable of wetting the particles to be removed.

+ Some contaminants are comprised of insoluble particles loosely attached and held in place by ionic or cohesive forces. The effect of ultrasonics is substantially the same in these cases.

+ The mechanical micro-agitation helps speed the dissolution of soluble contaminants and break the attractive forces of insoluble particles

(a) Dirty Surface

Figure 2 below illustrates the surface of the part being cleaned has been represented as a flat.

(b) Cleaning Process

(c) Mechanical Cleaning i.e brushing

Procedures of Ultrasonic Cleaning

MaterialCompatibility

Scale AnalysisPlanning Chemical

Selection

Design Layout

LayoutApproval

DevelopProcedure

DevelopJSA

BundleRemoval

BundleInstallation

EquipmentInstallation

ChemicalSoaking

Cleaning &Monitoring

ScaleAnalysis

BundleLifting

Bundle Rinsing

1st. Stage

2nd Stage

3rd Stage

4th Stage

Maximizing the ultrasonic cleaning effect

• Cleaning- chemical selection• Temperature• Degassing

Temperature• Cavitation effect is maximized

in pure water at 1600F• However, optimum cleaning is

often seen at higher or lower temperature because of the effect that temperature has on the cleaning chemical

• As the general rules, each chemical will perform best at its recommended process regardless temperature effect on the ultrasonic

Degassing• Degassing is done after the chemical is added is

accomplished by operating the ultrasonic energy and rising solution temperature

• Time required for degassing depends on tank capacity and solution temperature

• Degassing is completed when small bubbles pf gas cannot be seen rising to the surface of te liquid

Ultrasonic power• The delivered

ultrasonic power to the cleaning tank must be adequate to cavitate te entire volume of liquid with the workload in place

• Excessive power may cause cavitation erosion or burning on the soft metal parts

APPLICATIONS IN THE PLANT OPERATIONAPPLICATIONS IN THE PLANT OPERATION

(ii) Filter Cleaning- to remove plugging materials in filter pores.

(i) Tube/Plate Cleaning (reboiler, heat exchanger, condenser and column packing)- to remove scale and fouling materials

Depending on operation requirement, ultrasonic techniquehas wide applications particularly to improve processefficiency, retention time and cost. However for cleaning and maintenance purposes, the technique is very usefulfor:

(iii) Sludge Breaking- soften hard sludge in pit and tank

A.A. Dynamics Ultrasonic Cleaning System(DUCS) Dynamics Ultrasonic Cleaning System(DUCS) Flow Sequences (P&ID) - FPG Oleochemicals Flow Sequences (P&ID) - FPG Oleochemicals Sdn. Bhd.Sdn. Bhd.

System Specification Power Requirement ÉÉÉÉ..É 220/240VAC

Generator Frequency ÉÉÉÉ..É 40 Khz, 500 W

Design pressure ÉÉÉÉ..É 30 Bar

Operating Pressure ÉÉÉÉÉ.. 15 Bar

Design Temperature ÉÉÉÉ É.. 90 oC

Operating Temperature ÉÉÉÉ É.. 25-85 oC

Piping Connection ÉÉÉÉÉÉ Screwed type

Thread Standard ÉÉÉÉÉÉ NPT male and NPT female

Dimension ÉÉÉÉÉÉ 1.5ft (H) x 1.5ft (L) x 3 inch (w)

Material ÉÉÉÉÉÉ 316L Stainless Steel

Layout requirement ÉÉÉÉ..É Any configuration

SYSTEM CONFIGURATIONSYSTEM CONFIGURATIONFive main section of DUCS, comprises of:

1) Liquid container

- UOF accumulation tank - 4’ Diameter X 6’ Height - Made of SS 316L

2) Pipe fittings section - Major piping and overflow piping is fabricated from 1” SS 316L

and ½’ SS 316L respectively. Also including Pressure Control Valve (PCV), Ball valves, Globe valves, Check valves and Quick coupling system

DUCS major piping is fabricated from 1” SS 316L with threaded connection

4) Pumping Section- Consist of one Centrifugal Pump and Diaphragm pump that used to

pump the UOF to the DUCS and to recycle overflow of UOF back to the accumulation tank respectively.

Centrifugal Pump

Diaphragm Pump

5) Instrumentation Section- Consist of Electromagnetic Flowmeter, Pressure Sensors,

overflow level sensor and analog pressure gauges.

PCV

Outlet Pressure Transducer

Inlet Pressure Transducer

Inlet Electromagnetic Flowmeter

Pressure Gauge

Tube Bundle after cleaning

Tube Bundle cleaning skid

Chemical holding tank

Cleaning Bath

Tube Bundle during cleaning process

Cleaning Bath

Chemical

Tube Bundle after cleaning

BENEFITS

Reduces costs of cleaning, manpower, new bundlesand maintenance.

Estimated saving RM2 millions a year

Shorten period of maintenance from 7 days to 18 hours.

Reduces of risk exposed to toxic and hazardous chemicals.The technique used friendly chemical i.e. UOF Remover

Used UOF Remover has moderate properties that meetETS specification.

B. Stabilizer Reboiler Tube (External/Internal Cleaning) - Petronas Penapisan (Melaka) Sdn. Bhd.

Reboiler Tube

Portable Gun Transducer

UltrasonicsGenerator

Liquid (water)

FrequencyConverter

Transducer(immersed)

Stabilizer Reboiler Tube (External/Internal Cleaning) - Petronas Penapisan (Melaka) Sdn. Bhd. (….Continue)

Inlet Electromagnetic Flowmeter

TA Manager

Operator holding Portable Transducer

Harness. (Good Practices)

Ruptured bubbles (cavitation)

CleanedSection


Bundle cleaned with ultrasonic and UOF

chemical

Close-up view

Lifting from Water Bath. Ready for Hydrojet (Rinse)


Loosen Scale

Model Faces

BENEFITS

Reduces costs of cleaning, manpower and maintenance.

Estimated saving 40% of ordinary cleaning cost

Shorten period of maintenance to 8 hours.

Increase heat transfer efficiency up to 50%. Reducesflowing pressure drop up to 40%.

Reduces of risk exposed to toxic and hazardous chemicals.The technique used friendly chemical i.e. Oxide/Coke Remover Used UOF Remover has moderate properties that meetETS specification.

C. ULTRASONIC APPLICATIONS (i) Ultrasonic Cavitation (Clamping Type)

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C. ULTRASONIC APPLICATIONS (ii) Ultrasonic Cavitation (Immersible Type)

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C. ULTRASONIC APPLICATIONS (iii) Ultrasonic Cavitation (Plug-in Type)

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• Ultrasonic is not a technology of the future. It is very much a technology of today.

ultrasonic cleaning

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