Dear Ashishsteag,

Probably 4* 600 MW

This resulted in higher outlet temperatures and decreased volume flow.

If the pressure does not change, it has hardly an effect on power consumption.

In case the clearances between the housing and more the lobes themselves are increased, there should be no lobe contacts.

However, if the blowers are still running at maximum pressure with worn lobe-tips, the temperature becomes so high that the housing is distorting.

The inlet side (ambient temperature) does not expand as much as the outlet side (too high outlet temperature) causing the housing to bend.

The lobes are not bending, due to a constant equalized temperature.

The bending of the blower cylinder can cause the shorter side (inlet) to touch the rotor lobes in the middle.

This can be noticed sometimes on the colored paint close to the inlet.

In most cases, when this happens, it is a matter of seconds before the blower stalls and is destroyed.

The timing gear has two purposes.

1)the main rotor is driven and through the timing gears, the slave rotor is driven.

2)the timing gear keeps the angular rotation of the rotors synchronized and prevents touching of the rotors.

As the rotor clearances (radially and axially)are in the order of 0.2 to 0.4 mm, assembling of a blower (or any positive displacement compressor) is a job for an expert.

Check the measured inlet- and outlet temperatures with the data sheets of the blower at the operating pressures.

If the allowed outlet temperature is surpassed, the blower must be repaired.

(In most cases, a set of new rotors can be mounted)

Proper filtering of the intake air is absolutely required.

Take care ■

Dear Ashishsteag,

Timing gears are part of the compressor (blower) and are designed by the manufacturer.

-The timing gears should have minimum play, to make sure that the rotors cannot touch.

-The center distance should be equal to the shaft center distance.

-The gears should be designed for the power to be transmitted.

-the gear ratio must comply with the rotor rpm’s

In general, there is nothing special on timing gears.

Are the chutes fluidized?

Drying wet, agglomerated fly ash will not restore the flow ability or fluidize-ability after re-drying.

Preventing the fly ash getting wet is the best solution.

Make sure that the fluidizing air is not the source of condensed water.

This formula D=√n *d is correct.

The cross section area of D is equal to the combined cross section area of the n pipelines with the diameter d.

Applying the formula:

D =√n *[/b].

D =√3 *[150]=259.8 mm

The result is that the air velocity in the 150 mm pipes is equal to the air velocity in the 260 mm pipe. (Disregarding the pressure drop in the pipes).

Take care ■

Originally Posted by Ashishsteag

Dear sir,

How can we identify sets of timing gear??Can any ordinary meshing gear pair be used as a timing gear or is there a different nomenclature for it?

Secondly during the rainy season it happens that fly ash in the silo gets wet and we encounter frequent chokings in the chute inspite of using these fluidizing blowers which provide air via heater at the bottom of silo with a temperature of 120 degrees celcious,ceramic tiles are non sticky brittle materials,can they be used to line the chutes for reducing the frequent choking during the rainy season?

Lastly i read in a fludizing blower manual regarding the piping calculations,as such in case of multi blowers connected to a common discharge header(same configuration we have at our station too).

If "d" is the diameter of the discharge line of each hot blower,and "D" is the diameter of the common header discharge line

Then D>=√n *d

Now if like we have 3 fluidizing blowers each with discharge line diameter of 150mm,then the header diameter comes out to be 260mm but sametime it was mentioned that the velocity of the discharged air should be in the range of 20-25m/s and accordingly the pipeline diameter should be selected,in such a case how can one choose the appropriate size?

==========================================================================================

My dear friend Teus has been very helpful to you, I will add more information that you can use.

NOW as you have identified yourself as a rotary lobe blower

user "We" need more information from you.

1. Blower manufacturer: i.e. Roots/Dresser, Joy, Butler for example.

2. Blower frame size: i.e. 33

3. Drive type: i.e. twin V belt drive

4. V-belt size i.e. Bxx/ i.e. 3,450MM

5. inlet air fitration type i.e. oil

6. Is the blower mounted horizontally on a four footed pedestal OR

is the blower housing mounted vertically??

7. how often do you check the oil level in the gear box housing???????

a. how often do you grease the enf bearings????????

NOW to the much more serious part of the issue;

1. the inlet air HAS to clean and I mean clean!!!!

2. Do you have use an oil bath inlet air precleaner or a paper filter cartridge housing piped into the three blowers inlets?

3. Do you have a dairy milkhouse vacuum gauge test kit i.e.,

manufactured by i.e. "Delaval" to check the condition of the blowers under load?

4. where is/are the relief valve pressure regulator(s) for the inlet air???

a. have you replaced them at any point??

b. have the blowers pressure delivery system been properly adjusted for the elevation above sea level at your location????

5. YOU CANNOT EVER depend upon the tattle tale guages if so equiped because they are innaccurate and do fail.

NOW when you have rotary lobe blowers that fail the entire blower has to be scrapped and I mean scrapped!!!!!!!!!!!!!!!!!!!!

There are no reuseable/rebuildable parts in them!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I do not mean to be a wet set of woolies that have been rolled around in on muddy football pitch but lobe blowers are

something that cannot be saved when they fail except for scrap at the smelter.

If you are assembling new blowers from parts you cannot save the old parts and use them, not even the side plates!!!!!!!!!!!!!!

AS far as the timing gears are concerned:

one gear is the drive gear and the other is the driven gear.

The lobes are properly installed when the measured distance

is equidistant from the center of the inlet to the outer edge of the machined casting

on BOTH the inlet and outlet sides of the blower.

Once this is done you can install the gears and then weld them in place in the two lobes shafts that protrude through to the gear box.

This also holds the shafts of the blower lobes in place in the bearing housing as well. ■

Dear Ashishsteag,

Seems a normal blower.

The name plate data would give all the information required.

A three lobe blower generates a higher frequency sound, which is easier to reduce in a silencer.

There is no difference in applications.

If the inlet filter of the blower gets dirty and blocked, the absolute inlet pressure decreases.

At the same time, the amount of air flow is decreasing, because the air mass flow is a function of the absolute blower inlet pressure.

A pressure safety valve at the outlet will not see any pressure rise as the flow is reducing, causing reducing outlet pressures.

The lower inlet pressure also causes more hot air flowing back through the rotor clearances, causing even higher temperatures. More likely, the blower could also trip on high temperature.

This can expand the rotors to touching the blower cylinder and even destroy the blower.

Installing a self-cleaning filter assembly will solve the dependency of cleaning operations.

Success ■

Originally Posted by Ashishsteag

Dear Teus sir,

Thanks a lot for your replies,this forum is really helpful to me and lots of other people.

Hello Mr.izaharis,

Well i would give you the details of the hot blower installed(would go through the manufacturer catalogue),what i know is that its manufactured by Ingersoll Rand(HIBON) and it is a horizontally mounted three lobe blower mounted on a four footed pedestal,the motor is coupled with the driven using a V belt drive on a pulley.I have seen an oil splasher installed for bearing lubrication and the recommended oil for bearing lubrication is SERVO(INDIAN OIL) 320 i.e. oil with viscosity of 320 cst.

As stated in my first post there is frequent filter chokings in the suction due to fly ash leakages and it becomes the duty of the operator to clean the suction filter using compressed air every fortnight but they basically fail to do so,many a times the blower casing gets severely heated up maybe due to increased clearances or higher oil level(churning effect),basically there was no cooling mechanism for the oil and so are cooling it using water(set of coils for it)..many a times when there is too much fly ash in the surrounding air,the blower trips due to the increased differential pressure

There is a dead weight safety installed in the discharge line and it rarely opens up.

Can you tell me the difference between a three lobe and twin lobe blower and which one is suited for fly ash applications?

Originally Posted by Teus Tuinenburg

Dear Ashishsteag,

Seems a normal blower.

The name plate data would give all the information required.

A three lobe blower generates a higher frequency sound, which is easier to reduce in a silencer.

There is no difference in applications.

If the inlet filter of the blower gets dirty and blocked, the absolute inlet pressure decreases.

At the same time, the amount of air flow is decreasing, because the air mass flow is a function of the absolute blower inlet pressure.

A pressure safety valve at the outlet will not see any pressure rise as the flow is reducing, causing reducing outlet pressures.

The lower inlet pressure also causes more hot air flowing back through the rotor clearances, causing even higher temperatures. More likely, the blower could also trip on high temperature.

This can expand the rotors to touching the blower cylinder and even destroy the blower.

Installing a self-cleaning filter assembly will solve the dependency of cleaning operations.

Success

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Namaskar,

Adding a bit more to teus excellent explanation of the nature of the beast.

The simplest most practicle method of saving your blowers would be to either move them to a location where they can be fed clean air from a

very large triple gang of oil bath air cleaners; or one very large oil bath precleaner.

Or install the three oil bath air cleaners near the blowers if you have room.

IF it were me, and I had the authority and ability to do so I would move

all three blowers to a clean location where the three oil bath units can be placed

and run piping to the application as the blowers wil run normally with very little

pressure loss as long as there are no leaks.

I have uploaded an image of a Clarco oil bath precleaner for you here

As you can see there is plenty of surface area to collect the dirt and the oil pan is retrievable to clean and

add oil back the collection pan.

As the area is extremely dirty as you have mentioned in great detail the use of one of these units

would be a an "I must have it" call to management.

Placing a unit like this in dirty operating conditions will require more diligence in cleaning simply due

to the surrounding airs dust load hence the suggestion to replumb the three blowers to three pairs of

separate units to allow you to take one unit out of service to clean it and have plenty oof clean air

going back to the blower inlet when the ball valves are opened and closed to clean the dirt pans. ■

Dear Leon,

I once, came across oil bath filters in an alumina pneumatic unloader.

Every 40 hours, the oil had to be changed.

However, the oil with the alumina dust formed a paste like mass that clogged the rest of the filter internals and the piping behind the filter.

This caused a permanent extra pressure drop in the vacuum system and ruined the unloading rate.

I found the problem when I calculated a higher capacity than what was experienced in reality.

As the installation was operating 24/7, there was no real opportunity to search for an, at that time unknown, problem.

By simulating an extra flow resistance in the clean suction piping, the measured capacity and vacuums corresponded with the calculations.

Then, I decided to dismantle the filter and the piping and found the clogs in the filter and the piping.

When the problem was located, we cleaned the piping and took out the filters and replaced them by, at forehand prepared piping.

At the same time we replaced a wobbly filter plate, which was leaking, by a stiff filter plate in the filter receiver tank.

An oil bath filter in a dusty environment is not a good idea.

Take care ■

Originally Posted by Teus Tuinenburg

Dear Leon,

I once, came across oil bath filters in an alumina pneumatic unloader.

Every 40 hours, the oil had to be changed.

However, the oil with the alumina dust formed a paste like mass that clogged the rest of the filter internals and the piping behind the filter.

This caused a permanent extra pressure drop in the vacuum system and ruined the unloading rate.

I found the problem when I calculated a higher capacity than what was experienced in reality.

As the installation was operating 24/7, there was no real opportunity to search for an, at that time unknown, problem.

By simulating an extra flow resistance in the clean suction piping, the measured capacity and vacuums corresponded with the calculations.

Then, I decided to dismantle the filter and the piping and found the clogs in the filter and the piping.

When the problem was located, we cleaned the piping and took out the filters and replaced them by, at forehand prepared piping.

At the same time we replaced a wobbly filter plate, which was leaking, by a stiff filter plate in the filter receiver tank.

An oil bath filter in a dusty environment is not a good idea.

Take care

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Hello Teus my dear friend, how is the weather in the low countries??

I used Duetz oil bath precleaners on the air cooled diesels

underground and we had very good luck with them.

That is why I suggested they move the three air cleaners to a better location(clear air)

and add plumbing back to the blowers if possible.

pictures/images would certainly help.

If they are not taking care of things............

Makes me worry/wonder what size turbine they are using too and whether its bearings

are cooled with hydrogen fed by a two lobe blower.

............ ■

Hello Leon,

The weather: 12 degrC, a bit of rain showers. Temperature in the coming days decreasing to around freezing point.

Nothing like the severe cold in the US and Canada.

Oil bath filters on diesel engines work well if the dust load in the combustion air is not high.

In a cement stevedoring company they were used in the engine rooms, where there was normally no dust.

On the clean-up front loaders, working in a very dusty environment in the ship’s holds, desert filters with cyclones were used. (And often replaced, when the power reduced and the engine started smoking in the exhaust).

Moving the air intakes to a cleaner place is a solution. Moving the whole blower package to a cleaner place is even better.

Take care ■

Originally Posted by Ashishsteag

Hello everyone,

Today we encountered an abnormal sound from the root blower and it was due to the violent rubbing of v belts on the pulley during the start and after operating it for few minutes the noise was extreme, the discharge air moves through a heater and it wasnt working..I think its because the disharge is restricted due to choked fluidizing pads at the bottom of the fly ash silo?? Is it a correct prediction?

If someone hads tightened the belts too much it will make a huge amount of noise.

I would check that first and make doubly sure that the belts are not to tight.

The V belts should not have any more than 1/8 inch deflection-3 Millimeters

If the fluidizing pads are choked the relief valvve pressure regulator would eliminate and

air from flowing into the cicuit.

As I said I would strongly suggest you move the blowers to a clean air environment away from the

plant and plumb the clean air to the work and use a very large oil bath air cleaner for the three blowers. ■

Originally Posted by Ashishsteag

Sir,

Thanx for your reply.

During the operation of blowers,there's sudden violent scratching noise and it trip at times,I would surely check it out if the belts too tight,I was predicting if there's a blockage to the delievery air which is tremendously loading the blowers.

==========================================================================================

Namaskar,

I hate to be the bearer of bad news; your blower(s)

will suffer a catastrophic failure in a very short time.

As I mentioned I would strongly suggest that the blowers

be moved to a clear air area with a large enough

oil bath air cleaner for all three units or large oil bath

air cleaner for each unit.

photo images would be a big help for us here on the forum is at all possible. ■