1. What is the efficiency of your emitter ?

The efficiency of an emitter is related to the ratio between the infrared energy coming out of the emitter and the gas input to the emitter. We are talking about radiation efficiency. The radiation efficiency depends on several factors like: excess of air, position of the hood in the machine, Kw input, to name a few. A typical radiation efficiency range is from 50 to 54 %, with a hood in vertical position.

2. Does radiation efficiency decrease with an increase in power ( Kw input ) ?

Yes, it does. There is a 5 % difference in radiation efficiency between 5 and 8 Kw.

3. What is the maximum power input of your emitter ?

The power input is not just what determines the drying effect; the efficiency of the emitter has to be taken into account, as an example. The IR.D.S. emitter can be fired from 5 to 9 Kw.

4. Is there any limitation in the Kw input on a face-to-face situation hoods ?

Yes, there is a limitation on light weight grades, because the radiation will go through, heating the emitters located in front. As the emitter life time depends on the operating temperature, it is often necessary to decrease power input in such situation, if a reasonable life time is being expected.

5. Does efficiency decrease as emitter gets older ?

When the screen starts to corrode away, efficiency drops. Screen is a major contributor to the radiation efficiency. Typically, papermakers wait until the emitter is completely worn out; as emitter replacement is an expensive operation. In the meantime, gas consumption increases or machine might slow down in case of drying limitations. The IR.D.S. emitter is provided with a removable screen, which allows you to change it when it starts to be corroded away, without having to wait until the whole emitter is destroyed.

6. What does your emitter have a removable screen ?

An emitter is an expensive piece of equipment; it also takes time to replace it, which is also expensive in terms of machine stop. Screen corrosion is the most frequent emitter failure; when screen is corroded away, traditional emitters must be replaced. With the IR.D.S. technology, only the screen must be replaced. Also, in case of coating contamination, screen can be taken off on machine to clean the combustion surface.

7. What is the expected life time of your emitter ?

The life time is typically 4-5 years. Life time will depend on operating temperature, number of sheet breaks, coating contamination, …

8. What can we do against coating contamination ? Is it possible to clean the emitter?

In case of coating contamination, the screen should be brushed, while maintaining combustion air in operation. Metal fiber mat should also be brushed, with the screen taken off. In case of severe contamination, the emitter can be dismounted and the fibre mat cleaned, using special chemicals. This operation must be done in IR.D.S. premises.

9. Can we throw away the emitter once it has to be replaced ?

The answer is yes for traditional emitters. However, never throw away an IR.D.S. emitter unless it is completely destroyed. The IR.D.S. emitter can indeed be refurbished; the body of the emitter can be re-used, with 25-40 % savings, compared to new emitters.

10. What is the temperature of the IR.D.S. emitter ?

Recommended operating temperature of the IR.D.S. emitter varies from 950 to 1050°C.

11. How is ignition/detection being done with your equipment ?

IR.D.S. has designed an emitter with built in electrode, without pilot flame. Located between the screen and the fiber mat, these electrodes are unsensitive to air current or coating pollution.

12. What is the gas consumption of your emitter ?

The gas consumption depends on the calorific value of the gas being used.

13. When do you recommend to install air bars ?

Air bars can be installed for two main reasons : stabilize mechanically the sheet and improve mass transfer.

14. Is there any specific reason why you use metal fiber mat as combustion support rather than ceramic tile ?

Metal fibre has a key advantage over ceramic, as the emissivity is much better. The emissivity of ceramic is 0,30 vs 0,75 for metal fiber; as a consequence, actual infrared energy transmitted to the paper is much higher with metal fiber than with ceramic, at the same operating temperature.

15. When do we need to replace the screen of the emitter ?

When the screen is corroded away, the radiation efficiency dropt; consequently the screen should be replaced when the screen surface starts to show little holes in the metal. The screen being easily removable, this operation is easy and cheap.