Experimental Study of the Combustion of and Emissions from Olive and Citrus Pellets in a Small Boiler

Round 1

Reviewer 1 Report

Referee comments on the manuscript FIRE-2450402

 

Experimental study on combustion and emission from olive and citrus pellet in a small boiler

Adriano Palma, Francesco Gallucci1, Salvatore Papandrea, Monica Carnevale, Enrico Paris, Beatrice Vincenti, Mariangela Salerno, Valerio Di Stefano, Andrea Rosario Proto

 

This paper describes the use of pellets made from two different agroforestry waste materials (citrus and olive pruning) and their mixture for combustion in a small boiler. The emissions of CO, CO₂, NO_x, SO₂ and PM have been evaluated in the combustion tests of pellets of citrus and olive pruning and mixtures.

This work has little originality, little experimentation and important variables in a combustion process such as the draft used, in addition to the mass flow of fuel added to the boiler have not been evaluated. Neither have important parameters of the combustion process been evaluated, such as heat losses in the smoke (unburned or sensible heat), smoke outlet temperature, excess air coefficient, smoke outlet velocity, and the energy efficiency of the process. I think that it can be profoundly improved. I recommend the publication of this paper with major revision. I recommend that the authors revise the following articles:

Juan F. González, Carmen M. González-García, Antonio Ramiro, Jerónimo González, Eduardo Sabio, José Gañán, and Miguel A. Rodríguez. 2004. Combustion optimization of biomass residues pellets for domestic heating with a mural boiler. Biomass and Bioenergy. 27,145-154.

T. Miranda, S. Román, I. Montero, S. Nogales-Delgado, J.I. Arranz, C.V. Rojas, J.F. González. 2012. Study of the emissions and kinetic parameters during combustion of grape pomace: Dilution as an effective way to reduce pollution. Fuel Processing Technology, 103, 160-165.

 

Specific comments:

On page 4, section 2.1, the authors include “The higher heating value (HHV) was determined by Paar 6400 calorimeter.........”, it is not Paar, it is Parr.

Please, throughout the text, separate units from the numerical value of any parameter, for example 80 kWth, on page 5, first paragraph.

How many determinations of the different parameters were made to obtain the average value and dispersion?.

When evaluating the combustion process of lignocellulosic biomass residues, it is important to make a good characterization of them and this also includes the determination of the content of S and halogens (Cl and F) (causing acid rain), as well as the temperature from ash melting (causing unburned solids in the combustion chamber and clogging of the grate due to clogging of holes for primary air inlet due to slag formation).

The dispersion especially of NOx for O-p, CO for C-p and SO2 for C-p in Figure 1 are excessively high, this is inadmissible. For example, in order to adequately assess NOx emissions, which depend on the one hand on the N content in the sample, the combustion chamber temperature and the partial pressure of O₂ in it, it is necessary to know the coefficient of excess air used in each test. Some claims made in this section by the authors could be justified if this parameter were determined.

The authors affirm “Regarding the SO₂ emissions (Error! Reference source not found. right), they are strictly correlated to CO and worst combustion condition with higher CO variability led to higher and more variable SO₂ emissions”, on what basis do they make that claim?.

On page 8, lines 310-312, the author include the sentence “In figure 2 it is possible to see that the blue cloud, 310 indicating OC-p emissions, ………respectively”, I think that it is Figure 22, but I don´t understand why the authors includes Figure 22 and 33, it will be Figure 2 and 3.

On page 9, line 321 the authors include the sentence “Between………….in PTS emissions………C-p”, I think that it should be TSP.

On page 9, lines 326-327 the author include the sentence “Figure 33), measured with the ELPI, shows a great particulate abatement while the multicyclone filter was active (from 12:48 to 13:05) only for PM10 (in red)”, please revise.

The authors in the Conclusions section do not include conclusions but a summary of the article. The conclusions have to be direct, clear and concise. Please review.

 

The English style should be checked because some sentences are difficult to understand.

Author Response

Thanks for reviewing, we tried to answer every suggestion. 

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,

 

many thanks for Your article and Your delivered data.

Please, check Your English language.

Please, You need to add information about the fuel preparation: homogenization, pelletization and analysis.

Please, add more information about the number of repeatings of Your analysis and give statistical data on average values and variations - some of Your analysing data is not logical as a mixture should have an analysing data of content within the boundaries of the pure materials.

You can shorten Your introduction more to the topic.

You should give data about the pellet quality: durability, fines ...

You should explain the PCA a bit more according to the basics.

Page 6: Where are the chips coming from?

Page 6: At which temperature is the ash analysing conducted?

Did You mix the pellets or the raw material in before?

Table 3 and so on: A comparison to wood pellets and norm would be very helpful.

The values in Figure 1 are really worse for boilers -You should explain what happened.

To which oxygen the values are compared?

You must check more the combustion knowledge - a lot of Your hypothesis are already state of the art and You should conclude based on this knowledge.

Figure 33: not mg/m³ but numbers or is this calculated to mass? If Yes, how is this done?

It is well known that multi cyclones are not an adequate opportunity to reduce fine particles!

 

You should improve Your conclusions with the known knowledge and actual research literature!

Kind regards

Full check of english is required.

Author Response

Thanks for reviewing, we tried to answer every suggestion.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments for author File: Comments.docx

Another English language check and etiquette would be helpful.

Author Response

Thanks for reviewing, we tried to answer every suggestion you gave.

Author Response File: Author Response.docx