Analysis of Oscillating Combustion for NO_x−Reduction in Pulverized Fuel Boilers

Round 1

Reviewer 1 Report

An excellent paper, with a rigorous and stable background research. The method of air oscillations in order to obtain NOx diminution for sold fuels is quite new and innovative.

Remarks:

1. A well done introduction, with state of the art of the problem
2. A very good review of the NOx formation conditions and methods of reduction
3. A clear and comprehensive description of the experimental plant and instrumentation. 
4. An excellent test approach: calibration, measurements, sensitivity tests, statistical processing and graphical presentation of the results.
5. Sharp and valuable conclusions

Requests (if possible):

1. To describe in a phrase the mechanism that induces air oscillations
2. To break the figure 13 in two separate figures or to use logarithmic scale for y axis, in order to a better evaluation of the  CO2 and O2 concentrations.

Author Response

The responses to the Reviewer's questions refer to the file:

inventions1060905_with_tracking

Reviewer 2 Report

Dear Authors,

The subject matter is very important and interesting. Please clear up the following doubts.

1. The title is worded too generally - please focus on the topic of the work.
2. In the chapter Introduction, briefly complete 3-4 sentences about oscilating combustion and what are its results.
3. Expand the last paragraph of the chapter Introduction - the objective of the work and how the authors intend to achieve it - a few sentences briefly.
4. In chapter 2.2 clearly indicate the advantages and disadvantages of “oscillatory combustion”.
5. Please justify why the tests are carried out in a pulverized boiler with an attached rotary furnace, where coal dust is burnt. In my opinion, this is not a rational technology. Why is a rotary kiln used to burn coal dust? The rotary kiln is not used to burn coal dust.
6. Provide the characteristics of the pulverized coal boiler, including (the obligatory) efficiency before the test.
7. In Chapter 3, please briefly describe the test procedure and the characteristics of the fuels used.
8. Please provide the temperature distribution in the individual zones of the boiler furnace.
9. What is measured on the "0" line ?
10. Why the emissions of other exhaust components were not measured ?
11. Was the gas burner started during the tests and what gas was burnt in it?
12. Please justify whether the combustion gases from the rotary kiln did not reduce NOx during the combustion without oscillation and with oscillation.
13. Briefly on page 6 for each pattern 1-4, please briefly write what they will be applied to. These are unusual dependencies.
14. Why in the "Expert" model the level of intensity α = 5%. What it comes from.
15. In my opinion, the “Expert's” model is not good for this purpose. Better to use numerical CFD calculations here (e.g. Fluent). What do you think about it.
16. Line 268 - "………… .so additional calculations …… .." please explain what calculations.
17. How Equation 5 came about ?
18. Please explain the regarding stoichiomatry in chapter Conclusions: lines 407, 412, 414, 420, 489, 493, 497? It is not understandable - is it worth writing about? It doesn't to brings anything
19. Why, for example, for positive results, was the boiler balance analysis with determination of its efficiency not carried out?
20. At what boiler operation parameters was oscillatory combustion carried out?
21. Please edit the section Conclusions. Please focus on the test bench, research methodology and the results obtained (short brief descriptions). Please do not use the signs R1, R2, please write what they mean. Discuss an unusual test stand  and research results. Quit discussing stoichiometry.

Sincerely,  Reviewer

Author Response

Please see the attachment.

Author Response File: Author Response.pdf