Heavy industrial central extraction

Naaykens has extensive experience in the design of heavy industrial central extraction for production processes that involve a lot of industrial dust. Our designs therefore take into account the additional risks involved in very dusty industrial processes.

With our experience, we therefore apply various methods to be able to filter and remove large amounts of dust from process air. Consider:

We carefully analyze the specifications, conditions and situation at the customer’s production facility.
Here we look at all the properties of the dust and its source;
We design, select and manufacture appropriate piping to prevent accumulation of the industrial dust with the right optimal life for the right cost;
The consultants consult and determine with YOU which collection method is best for the disposal of the large amounts of dust;
Designers can integrate customer-specific components or requirements into heavy-duty industrial central extraction in a very flexible manner;
The engineers and technicians at Naaykens Luchttechniek can analytically and predictively determine which filter cloth needs to be applied in order for the central extraction to operate successfully, with an optimal lifespan;
Finally, we often design the system so that the process air is clean enough to be reused.
In some cases, the industrial central extraction system even filters the air so clean that it can simply be blown back into the hall.

An example of parts of a heavy-duty industrial central suction
There are many different options available for complex industrial suction systems.

Design heavy industrial central extraction: the dust composition

The first step in designing a filter is usually an analysis of the industrial dust. In cooperation with a reputable laboratory, a dust sample is analyzed. From this it becomes clear that there are several fractions of dust, but with the largest fraction being relatively coarse.

Large amounts of dust - switching filter

We then work with the customer to determine the specifications that the heavy-duty industrial central extraction system must meet.
In this case this was:

Dust load	600 kg/h
Flow rate	30,000^m3/h
Dust concentration input air	20 ^g/Nm3
Emission standard	< 0.1 ^mg/Nm3

1: Here the high dust load is particularly striking!

Fabric Features
Description	Ceramic Grinding Dust
Density	2.65 ^g/cm3
Explosive?	No
Corrosive?	No

Particle size distribution
Substance size	Percent
< 60 µm	90%
< 40 µm	50%
< 20 µm	10%

Return blowing of the filtered air into hallway

Another wish was to blow the air back into the hall. With a flow rate of 30,000 m3/h, this is a wise choice, so the warm air is reused in the winter. With the high gas prices of 2022, this quickly saves €100 – €150 per cold winter day!

Design details heavy industrial central extraction

Anti-abrasive inlet and pre-separator

The first step to separate the (in this case) industrial ceramic dust from the air is done before the fabric filter, at the inlet. Due to an abrupt change in airflow in both direction and speed, the coarsest ceramic dust will precipitate on a grid in the anti-abrasive inlet. This precipitated dust will immediately form a buffer layer on which the other ceramic dust will collide, and if this layer becomes too thick it will be carried by the airflow to the outlet funnel, where it will be directed toward the collection tray.

1: Airflow through intake tube, anti-abrasive inlet and inlet bowl.
The further into the system, the lower the air velocity.

2: Coarse dust, due to the deceleration in air velocity, settles in the anti-abrasive inlet; where it falls on the other ceramic dust.
Thus, this forms a self-replacing layer that prevents wear on the structure.

Velocities of dust and air in industrial central extraction

In order to guarantee that all dust particles are taken along by the entire system, we use our experience and knowledge of air technology. Consider the speed at which this ceramic dust is carried from a certain size and at what speeds it will precipitate. We successfully and accurately predict at what velocities the dust would precipitate and at what velocities the dust goes along. We then adjust the heavy industrial central extraction completely to this.

For this ceramic dust, the critical velocity of a dust particle with different representative diameters was determined. With these determined values, we were able to determine that in the suction line at a high velocity of 20 m/s, even the coarsest ceramic dust would be carried along, only to precipitate further down the filter, exactly as it was intended.

Separation rates per filter step

In the table below you can see an example of an overview of where we separate the ceramic dust by part of the filter: (values are for illustration, in reality they differ)

Technical characteristics filtration per separation step
	Anti-abrasive inlet and baffle plate	Filter	Afterfilter – F9	Afterfilter – H13
Particle size offered air	Mainly coarse to very coarse dust: 90% > 20 µm	Medium coarse dust after separation of coarse residues. Largest part 5-50 µm	Fine to very fine residues after main filter Largest part: >0.4 µm	Fine to very fine residues after main filter Largest part: >0.4 µm
Dust load	600 kg/h	60 kg/h	300 g/h	15 g/h
Dust concentration input air	20 ^g/nM3	2000 ^mg/nM3	10 ^mg/nM3	0.5 ^mg/nM3
Separation rate	Approx. 90% of total dust	Approx. 99.5% for medium dust	Approx. 95% for fine dust	Approx. 99% for very fine dust
Mass flow rate of dust in outgoing air	60 kg/h	300 g/h	15 g/h	0.15 g/h
Dust concentration outgoing air	2000 ^mg/nM3	10 ^mg/nM3	0.5 ^mg/nM3	0.005 ^mg/nM3
Expected separation and collection of dust	Approx. 540 kg/h	Approx. 60 g/h	Approx. 285 g/h	Approx. 15 g/h

Impression of supplied extraction system

The installation below also meets our design requirements: something we check, of course, through a dust emission measurement. From this came That we were still conservative with our calculations; the emission standards are easily met!

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Do you also have a problem with stone dust? We are happy to take a look and can offer you customized, no-obligation advice.