Dust monitors

How to select the right dust monitoring technology?

Dust monitors are commonly used to detect, determine and quantify the presence of solid dust particles present inside a gas mixture.

The dust monitors are often separated in two categories :

• 1 - the process dust monitoring systems
• 2 - the emission dust monitoring system (dust CEMS for Continuous dusts Emissions Monitoring System)

And depending on the application, the two most advanced technologies / methods, may be used:

• A -  an optical technology with LED light backscattering method
• B -  the inductive electrification method (advancement of the old triboelectric technology)

The table shows globally which method is preferred for which function, and which Fuji Electric dust monitoring equipment is required for precise measurement

When emission monitoring is concerned, i.e. a dust CEMS is required, both technologies may be selected.
And the choice will depend on the application specifications.

The next paragraphs explain in detail how to select the right dust monitoring devices according to the application.

Case 1 : The process dust particle monitoring systems

   The dust monitoring system is used to either detect solid particles, or quantify the concentration of solid particles in a gas flow.

• A good example of dust detection is a broken bag filter dust monitor. Such a dust detector will inform immediately the operator that a filter is damaged. The operator will save time, money and environmental impact while reacting fast and recovering a valid process.
• Concerning process dust monitors with a trend reading and output, these are used to measure the particle count inside a gas stream.

Examples can be:

• Monitoring the dust concentration downstream a filter. When this dust concentration measurement starts drifting, the operator gets the information that soon the filter may be cleaned or replaced.
• Monitoring the quantity of solid particles flowing in a pneumatic conveying system. For instance, measuring the flow trend of cereals in a pipe in the agriculture industry or sugar particles in the food industry.

Process application: pneumatic conveying system monitoring.

• For process applications, the preferred dust monitoring technology is the inductive electrification method.

This is the high and latest advancement of the old and famous “triboelectric” measurement method.
We explain the difference in the Fuji Electric S300 Series technical description.

Why choose triboelectric (or inductive electrification) dust monitor for industrial processes dust monitoring?

The solid particles in many cases are flowing through a small diameter duct.
The inductive electrification dust monitoring equipment can be configured for both medium and small-diameter ducts.

Case 2: The emission dust monitoring systems

When dust monitoring is used to measure the concentration of solid particles emitted to the atmosphere by a combustion process or any other industrial process, then both technologies may be used.

What are the criteria to select emission dust monitoring equipment?

1. Compliance with local environmental and federal regulations
2. Metrological performance
3. Resistance to harsh industrial environment
4. Fast and easy setup
5. Low and easy maintenance
6. Real-time data
7. Remote monitoring

With Fuji Electric's smart design and QAL1-certified dust monitoring systems, both LED backscattering and inductive electrification methods fulfil these 7 conditions.

In which case choosing an inductive electrification dust monitor for CEMS purposes?

A dust monitoring system with inductive electrification technology is used when the flue gas stack diameter is small or medium size.
And according to other process specifications such as flue gas temperature and velocity, type and nature diversity of particles flowing, and type of filter used in the process … one or the other method will be selected.

Is it possible to use a triboelectric dust monitor when there is an electrostatic precipitator (ESP) filter in the process?

The answer is No  … but…

• No, as a basic triboelectric dust monitor’s response will be impacted by the ESP operation.
• But … the inductive electrification technology actually makes it possible:

So, finally, YES the Fuji Electric S300 series dust monitors, using inductive electrification technology are used even when the particles are filtered by an ESP. The only case where it is not possible is when the S300 series dust monitor is located right downstream of the ESP. But in most cases, there are some distance and/or flue gas treatment processes between the ESP and the dust monitor, such as :

• NOx minimization process (DeNOx SCR most commonly)
• Desulphurisation process
• Bag filter fine small particles removal step

In which case choosing an optical LED backscattering dust monitor for CEMS purpose ?

A dust monitoring system with LED backscattering technology is used when :

• the flue gas stack diameter is medium or large
• the flue gas velocity is high, low, and even very low
• an electrostatic precipitator is placed right before the dust monitor location
• there is a large flue gas flow rate variability that cannot be measured

  See more detailed explanation on Fuji Electric ZFDM-4 technical description.

In all other cases, the industrial operators are free to choose one or the other technology.

In case of any doubt, Fuji Electric France experts and Fuji Electric France partners will be glad to support you in selecting the best solution for your dust monitoring measurement application.