MINING PUMP -SAND -SITE -BIDOR

Sand is highly abrasive material to be pumped and the following operating parameter shall
be considered

Right Speed : Operating the pump at 4000 rpm is certainly not right
Lower or check the actual system head and bring down the
speed to correct Duty Point.Ideally the pump speed should not exceed 1200 rpm

Right Material of Construction

Rubber Lined being used now , is suitable but however due to the high operating speed .the
wear and tear is still high .Another contributing factor is the sand particle size of 4 mm , which
may cut the rubber material

Ceramic Material can be considered for this case . Get a pump with ceramic lined of
5 mm thick . The pump speed should still be low

Shaft Sealing of Pump

Athough mechanical seal is the best option, but in a long run it is still not economically
to use .Tungsten material will still fial after few months due to the abrasive nature
of pumping media - sand

Gland packing is simple and cheap .

Pump Not Achieving the Required Rated Pressure

Ejectors are use at tank bottom to agitate the sand so that it does not settle down
at the bottom . By doing this , you are creating a lot air which goes to the inlet
of the suction , cavitating the pump and this could be another resaon that the pump
inlet area and impeller is wearing out very quickly
See if you can minimise the ejector air

Cavitation also cause loss of pressure


Working Out The System Head
Determine the total length of pipe and diameter , and the static head
to obtain the Total Head

PLATE HEAT EXCHANGER (PHE ) - TROUBLE SHOOTING

PHE is a static piece of equipment ,the heat exchange rate or capacity is dependant on the surface area designed for the heat load .

For units that has been operating a while and one day failed to perform , fouling is the likely
cuase .The unit need to be cleaned or serviced

Another possibility ,check the gasket , if it is very old and flattened  due  overtightening during
maintenance .These gaskets has become too flat , narrowing  the flow passage thus reducing the flowrate

Monitoring the pressure drop is one way to determine if fouling has taken place
Before commissioning the unit ,take note of the pressure at inlet and outlet and record the
pressure drop[ across the PHE.If the pressure drop is high after a while ,then flouling could have set in

The right presure drop /velocity will help in reduction of fouling .The fluid velocity must be good enough to create some turbulence to self cleaned the walls of the PHE

In the case of new units . if the new unit is not working according to the designed parmeter,
check the following
a) is the actual heat load same as the design? calculate the head load l/sec x 4.18 ( specific heat for water and Temperature Difference = Kw , and check against designed temperature profile

b) is the process media flowrate correct? check with a flow meter or simply note the operating pressure and check pump curve for actual flowrate . May also check running ampheres or BHP
the flow is too high ,throttle the flow to designed flowrate

c) Is the flowrate of cooling water sufficient? If the oulet temperature from PHE is too high
this may be an indication that flow(service water ) is too low
check the pump curve

There is also pressure drop across the PHE ,ranging from 0.2 bar to 1.5 bar or higher depending
on factors such viscosity ,sizing of the PHE itself

We came across recently two cases of pmps underdesigned
System head is about 2,5 bar ,whereas the pump head is max 2 bar.This cause the pump
to be operating on the left of the pump curve and thus,.very low flow .
The head loss calculation was not complete ,the head loss of 1.5 bar accoss the PHE was not taken into consideration

The system head

a) static Head : 4 meter
b) head loss (PHE ) : 15 M(left out )
c) head loss ( pipelines ): 3 M
d) Total head : 22 M

Pump Max head : 18 m
Designed Flow : 400 m3/hr
Actual flow : 260 m3/hr

Solution : upgrade pump to 400 m3/hr at 25 M head

Handling of Water Pump with Contaminated Wood Dust

Dear Mr Nadarajah

The present pump that you used is DAB closed Coupled pump for clean water or domestic water application.The solid passage between the impeller plates is small gap ,approx 4 mm
This is why the Pump is getting choked and motor over loaded,a s the water you are pumping
is having high percentage of dust

A right pump with be an open impeller pump , with soild passage of 10 mm or more
and the solid content should not exceed 15% for closed coupled pumps
Pefer Not go for Pressed Metal ,but casted material which are more heavy duty

End Suction pumps with wider impeller vane with is a better option,but the pump need
more spaces and higher is cost ,the motor can be over sized slightly in case the
solid contents gets too high and motor will not be overloaded

Closed Coupled Pumps ,the motors are rated to Water Curve . SG of 1 .0 low viscosity and no solid
and you cannot over size the motor as the pump motor mounting is fixed for certain frame
size

CAVITATION

Cavitation is a hydraulic condition which can exist in any type of pump
It is primarily a situation in which the pump is discharging less liquid than its rated
capacity due to reduction or lack of supply to the pump
Common causes are
a) excessive suction lift
b)Net positive suction head avaialble is insufficient
c)selected operating speed is too high

Pitting,vibration and noises are common troubles stemming from cavitation

Severe cavitation will cause excessive noise and mild cavitation will give a small reduction
in pumping efficiency and moderate wear of the pumps parts

What you can do :-

a) slow down the pump
b) reduce suction lift
c) increase positive head pressure (reduce the suction head losses )
d) use bigger pump if you are not able to accept the
reduction of flow

Before going for the bigger pump . what is the right pump .........calculate
the NPSH avaialable ( NPSH A) , and the NPSHA must be higher than
NPSH required by the pump

Look up earlier postings on NPSH A

Open Impeller Slurry Pumps

http://www.chemfluidpumps.com/

the Samson AM series is capable of handling solid size of 30 mm and solid content of 30 %
It is very popularly used in PalmOil mills effluent pond and sludge pit
The shaft diameter is 38mm and with heavy duty bearing pedestal

PNEUMATIC CONVEYING - AIR FLOW REQUIREMENT & CYCLONE DESIGN

Information Required To Size A Blower

Example
Product : Dried Cocoa Shell
Capacity : 400 kg/hr
Density : 0.55
Total Pipe Length : 330 ft
Vertical (static head ) : 40 ft
Nos of Bends: 5 nos
Pipe diameter : 3 ''

The above will need about 330 m3/hr of air and operating pressure of approx 400 m Bar
and Motor Kw is about 7.5 kw

The air volume is very much dependent on capacity and density of product to be transfered
Pressure is the static head plus pressure losses on pipe length and fittings

For drive arrangement ,best option is belt driven if you need to fine tune the
performance of blower to the closest duty in actual operation

In conveying of Plastic resins .the discharge temperature is an important factor .if
temperature is too high the plastic resin may melt or get distorted in shape and size

For Areation application in Sewage Treatment Plant , air volume is equally important
but is often ignored
the right amount of air used will ensure effectiveness of the areation

Another important equipment in pneumatic conveying is the Cyclone
Most of the time .people will look at the blower if there is problem
The Cyclone has correctly design to suit the application allowing right pressure drop for product of different density,so that the lighter particle get transported away and heavy particle get collected at the bottom of the cyclone

Assuming the Cyclone is designed to handle a fixed capacity and a particular density
Increasing the fan speed will cuase more lighter particle to be carried over
and reducing the speed /capacity will cause a drop in throughput
In the wood industry dust collector cyclone system,there ia a battery of cyclones to handle different particle size /density
and at the last stage .only air(without any dust ) is discharge from the system .

Media Not Reaching the Pump

Got a call from an Engineer " hey , how come the oil cannot enter the pump suction "
Any chokage . valve open ? Answer "No ''
Suction is positive

For this case ,the suction head is very low due to close loop installation and discharge line is also
pressurised ,high back pressure
When the pump was removed and new pump installed ,the pump should be primmed
or air release by remove the nut on the pump body ,then plug back the nut and start pump
make sure rotation is correct

If it is negative suction. the suction line must be filled with media for the first time operation
and make sure foot valve is installed if it is not a self primming pump
Some Engineers still think that self primming pump need not be primmed at all

In most cases .it is the failure to read operation manual provided before commissioning
Pump suppliers will always be called to go to site before the Engineer would determine the
fault .always the pump fault , not working

TANK CLEANING -ALFA LAVAL SPRAY JET

USEFUL FORMULAS

Some useful formulas for pump users

BHP( KW) : 0.163 x m3/min x head ( m ) x sg / efficiency ( % )
This is will indicate the BHP in Kw


Velocity ( m/sec )= Q ( M3 /HR ) X 353.60 / D2 ( pipe diameter in mm )

Recommcneded velocity
Suction Line : 0.5 to 1.2 m/sec
Discharge Line : 1 to 3 m/sec

Option : the lower the better , however it is piping cost versus power consumption
over a long term period .Greater saving on power if motor is bigger

see earlier posting on this issue

PUMPS REVIEW

1) ALFA LAVAL SOLID C
- very solid looking material and nice finishing
- can be mounted to IEC standard Foot Flanged motor
- one set of mechanical seal for all ranges of Solid C- low invertory cost
-Front loading shaft seal design ,the seal can be changed in minutes without removing the backplate
- complies with 3 A. CE and with EHEDG certification
- simple competitive and yet good operating life,only maintenance kit is one pcs of casing O ring and a set of mechanical seal

Suction Under Vacuum

attn : Mr Ang

Under such pumping condition , workout the NPSH available in the system and get pump with
lower NPSH required .It should be lower than NPSH avaialable otherwise the pump is not going to work

For this application ,it is under 10 m bar which is almost 98 % vacuum .
therefore 10 meter x 98% is = 9.8 meter
NPSHA = 10 METER - (scution pressure + vapour pressure ) = 0.2 M
NPSH AVAILABLE IS 0.2 METER
Vacuum ejector is mostly use for this particluar installation(palm oil refinery )
The suction head loss and vapour pressure for above is not taken into consideration
as it is negligible

VIBRATION - CAUSES AND EFFECTS

Vibration can cuased serious effects to pumps as well as other rotating equipment

The causes of vibration can be due to mechanical or hydraulic reasons



Mechanical fault

a) most common is unbalanced impeller .shafts . worn out impeller or even coupling
it is quite common for maintenance personel to change damaged bearings
and put the pump running

b) worn out bearings

c) misalignment of pump and driver

d) Pipe strained

e) mass of pump being too small

f) loose screws on pump mounting or baseplate

g) bent shaft

HYDRAULIC REASON

a) cavitation

b) air in the system ,leak or vortexing

c) too high speed of pump

EFFECTS
a) damages of mechanical seal and the life of mechseal is directly related to the
shaft movement
b) bearings and other pump components

Give A Pump 6 to 10 bar?

Again , we still recieving enquiries with this requirement of 6 to 10 bar
The operating pressure should be known and specified ,not max pressure

For such specification, pump suppliers will clarify with you or based on 10 bar as operating pressure . If the operating head is only 6 bar ,then you would have bought an excessively oversized pump. paying more for a bigger pump and paying more for running cost in term
of higher motor kw .

Also sometime flowrate ,given as 100 to 200 lpm

AN EXPLODED VIEW OF ROBUSCHI RBS ROOT BLOWER

MAXIMUM WORKING PRESSURE AND TEST PRESSURE

There is some misunderstanding of maximum working pressure and test pressure among some pump users
a) DIN 24255 pump do specify Maximum Hyrdostatic Test Pressure of 24 bar , note this is test
pressure done hydrostatically and not operating condition

b) Maximum Working Pressure at 16 bar at maximum speed of 3600 rpm ( 60 hz 2 pole )
In Malaysia ,it is 50 hz 2 pole ,which is 2900 rpm

Therefore .again specify the operating head rather than maximum 16 bar as what we
encounter this morning

Customer wants a pump maximum 16 bar but for circulating purpose only which we reckon that then system head to be only about 3 bar or 30 M
And flow . 350 m3/hr at 16 bar ?

Big motor kw is required for this duty

Verticle Sump Pump Mounted on Poontoon in the Effluent Pond at a Palm Oil Mill
This pump serve as disludging pump and as an aereator

PUMPING IN CORROSIVE ENVIROMENT

In most cases , we tend look at pump material of construction when come to handling of corrosive pumping media and this usually cause no problem if the materials are compatible to the media to be pumped

However the construction material of drive components like geared unit or motor is often ignored .If the pump media are store in open tank , evaporation takes place rendering
the working area to be full of acidic fumes .These fumes will then corrode the gear nox or motor
which usually in cast iron construction . You almost never come across motor with SS body ,right ?

Solution

a) get the work area well ventilated
b) coating of the Gear unit and motor with proper coating
c) choose a motor that is Aluminum body , plastic fan cover and plastic
terminal box

These will surely extend the life of it and lower the maintenance

A customer in Gemas has been paying good attention in this issue and I am glad
to hear one of the pump has been able to last