The air consumption is depended on the:

- size of valves

- quantity of valves

- time between each pulse

Regarding to myself experience for a bagfilter with the capacity 90,000 m3/h which we have used 42 vlaves with 2" size, the air consumption is about 252m3/h which is ten times of yours!!

Maybe other bulkoholics have different experiences. ■

Dear Mehdi Omadi,

From your data:

The filter area is 96000/60/1.06=1500 m2

Area of each bag = π * 0.16 * 5 = 2.51 m2

Number of bags = 1500 / 2.51 = 600 bags

An average bag filter pulse air consumption is: 0.0865 m3/sec

Which means for 1500 m2 1500 * 0.0835 = 0.00865 m/sec.m2

For a filter area of 1500 m2, the pulse air requirement is: 0.00865*1500*60 = 7.78 m3/min = 467 m3/hr.

Your doubts are more than justified.

Even the example of Masoomeh Mohandes is considered to be on the low side, although f.i. the Air to Cloth ratio is not given. (or I estimate the pulse air consumption too high)

NOTE:

The bag length of 5 m is extremely long and the question should be asked, whether the cleaning pulse is strong enough (enough energy) to get to the lower section of the bag.

Take care. ■

Originally Posted by Teus Tuinenburg

Dear Mehdi Omadi,

An average bag filter pulse air consumption is: 0.0865 m3/sec

Which means for 1500 m2 1500 * 0.0835 = 0.00865 m/sec.m2

For a filter area of 1500 m2, the pulse air requirement is: 0.00865*1500*60 = 7.78 m3/min = 467 m3/hr.

.

Dear Teus,

Would you please explain this calculation, it seems there are some missing parts:

- you assumed 0.0865 m3/second an average pulse air consumption, experimental or it has reference? what is the meaning of average, for which condition?

- 1500 m2 ? 1500 * 0.0835 = 0.00865? ■

Originally Posted by Teus Tuinenburg

Dear Mehdi Omadi,

An average bag filter pulse air consumption is: 0.0865 m3/sec

Which means for 1500 m2 1500 * 0.0835 = 0.00865 m/sec.m2

For a filter area of 1500 m2, the pulse air requirement is: 0.00865*1500*60 = 7.78 m3/min = 467 m3/hr.

.

Dear Teus,

Would you please explain this calculation, it seems there are some missing parts:

- you assumed 0.0865 m3/second an average pulse air consumption, experimental or it has reference? what is the meaning of average, for which condition?

- 1500 m2 ? 1500 * 0.0835 = 0.00865? ■

Dear Masoomeh Mohandes,

You are correct, I made a mess of the formulas.

Here the corrections.

An average bag filter pulse air consumption is: 0.0000865 m3/sec.m2

Which means for 1500 m2 1500 * 0.0000865 = 0.1295 m/sec

For a filter area of 1500 m2, the pulse air requirement is: 0.0000865*1500*60 = 7.78 m3/min = 467 m3/hr.

During my career, I installed a lot of filters in grain unloaders, silos and cement unloaders.

Listing the pulse air consumption of these filter assemblies, an average pulse air consumption was approx. 0.0000865 m3/sec per m2 of filter area.

(Some filters used more, some filters used less air)

Appreciate your feedback very much.

Have a nice day ■

Dear Teus,

Many thanks for your explanation.

Meanwhile I should explain that our calculation for air consumption is depended on the valve size and quantity.

We assume for each 1.5" valve: 4m3/h air consumption and for each 2" valve: 6m3/h

So in my example we have used 42 valves (2") so the air consumption will be:

42*6= 252m3/h

However to be in safe side, our recommendation for compressor size is twice this value. So we recommend our customer to install a compressor of the capacity 252*2=504m3/h

In this case it seems our experiments are near to each other.

It seems the competitors try to show some benefits for their equipment and claim that their design consume air much lower. I think it should be a way to reject these claims by evidences and/or documents so that they couldn't mislead customers.

Meanwhile please accept my best wishes for the New Year full of happiness and peacefulness ■

Dear Masoomeh Mohandes,

By controlling the pulse air pressure before the membrane valves, the pulse air volume can be controlled.

In your approach, you must also have a certain square meters of filter area, which corresponds with one valve, set at a certain pressure.

If that is the case, both estimates are equal.

A safety factor on the compressor volume is always recommendable.

I use this approach just for calculations and pre-designing . As soon as the design is complete and the filter assembly is selected, the design calculations are repeated with the actual data from the supplier.

I am honored with your best wishes for the New Year, full of happiness and peacefulness and wish you the same prosperity.

Best regards ■

Dear Mehdi Ohadi

Yes, if you reduce the pressure before the membrane pulse valve, the pulse air consumption also reduces.

If you reduce the pressure before the membrane pulse valve to 0 barg, then the pulse air consumption also reduces to zero.

It is obvious, that the filters will not be cleaned then.

I understand, that you consider the required, optimum energy for cleaning a filter bag as constant.

However, by controlling the membrane opening pressure, you are controlling that energy. (Energy = function of pressure*volume)

It is much easier to control the membrane pressure and measure the filter pressure drop, to find the optimum cleaning pulse.

In this way, under cleaning as well as over cleaning is prevented.

Filter manufacturers have established all these practical values in their built installations and advise the pulse air pressure and -consumption to their customers.

Have a nice day ■

Thanks to Mr. Teus for his effort and explanation, however:

It seems that some companies claim that they can reduce air consumption half of the others or as the Mehdi first thread one-tenth of the others! I think as the energy required to clean the bags is nearly constant their claims could not be true, isn't it? ■

Going back to the original question of Mr. Mehdi Ohadi:

Checking, whether a filter is working properly is by measuring the filter pressure drop under various conditions, taking into account the filter airflow, the pulse air flow and the dust load.

A too high filter pressure drop keeps the dust against the filter surface.

Bag filters are cleaned by stretching the bag by the reversed air flow and thereby shaking off the accumulated dust. (In the past, this effect was generated by mechanical shaking)

Filter elements are cleaned by actual reverse air through the filter element, blowing back the accumulated dust.

Companies, that claim unnatural low pulse air consumption (the energy hypothesis of Mehdi) will not survive in the market.

(Although it can take a long time before everybody in the world is cheated)

In addition, filter technology should not be simplified to pulse air consumption only.

best wishes for everybody. ■

Dear Mr. Ohadi,

you can find another description for calculating air consumption in below address.

https://www.mikropul.com/blog/detail...gfilterbags/

As Mikropul described:

the optimum compressed air flow rate for filter bag cleaning in a pulse jet dust collector is twice the upward flow rate through the filter bags. ■

Dear Masoomeh Mohandes,

In the link to Mikropul, a simple calculation is explained in a complex way.

Reducing the text, describing the pulse air consumption, I think the following formula is explained.

Pulse air consumption = 2 x pulse duration/pulse interval x filter airflow.

Example:

pulse duration = 0.1 sec

pulse interval = 60 sec

Pulse air consumption = 2 x 0.1/60 x filter airflow. = 0.0033 x filter air flow (approx. 0.3%)

Whether this pulse air consumption is optimum for all materials and for all circumstances, I do not know.

Nevertheless, it seems to be a good approach.

Take care ■