Production of Carbon Black in Turbulent Spray Flames of Coal Tar Distillates

Round 1

Reviewer 1 Report

Conventional carbon black production occurs by pyrolysis after heavy aromatic feedstock is injected into the post-combustor region of furnace black reactors. The current work examines the conversion of the coal tar distillate in turbulent spray flames to demonstrate a more compact reactor configuration. Coal tar distillates diluted in toluene is atomized and burned in a standardized flame spray synthesis configuration known as SpraySyn. Flame conditions are characterized by thermocouple, soot pyrometry and image analysis and product particle properties are examined by TEM and Raman spectroscopy. The measured flame temperature corresponds to the range of temperatures used in the furnace black process, but the current synthesis includes oxidizing conditions and faster residence times. The resulting carbon black particles are aggregates having primary particle size on the small end of the carbon black size spectrum according to analysis of TEM images. Carbon black formed under a range of flame temperatures show Raman spectra with features resembling typical carbon black materials. Conversion of coal tar distillate to carbon black by direct flame synthesis may be a scalable method to produce high-surface area grades without a conventional pyrolysis reactor stage.

 

I think this is an important study work on soot measurements on turbulent spray flames of coal tar 2 distillates, which can guide the control of soot emissions on spray combustion, so I recommend to publish it on Applied Science after some necessary revisions.

 

1. In temperature measurements, both thermocouple and two-color method are used, while as using thermocouple, the formed soot could wrap the tip of thermocouple, which can affect the test of temperature, so the author should analyze and clarify the difference between thermocouple and 2-color method. The relevant works, such as Energy & Fuels  2019, 33: 11821-11829 and Combustion and Flame, 188:129-141, 2018, introduce the both methods, and these both papers should be cited and help to improve the presentation on temperature measurements.

 

2. The scale of the length in Fig. 6 should be added to make the images clear to be read.

 

3. Fig. 7 is not clear to be read, which should be replaced.

Author Response

Thank you for the feedback please see the attached for detailed responses.

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript examines the conversion of the coal tar distillate in turbulent spray flames to demonstrate a more compact reactor configuration, it is a relatively new synthesis method. Flame temperature is an important factor affecting the synthesis efficiency, so the flame temperature was measured by thermocouple and the soot pyrometry. There have some questions need to answer before the manuscript could be published.

1. The calibration coefficient of the soot pyrometry should be given in this manuscript, is it calibrated by the blackbody furnace?
2. The flame in this manuscript is asymmetrical and cannot be solved by using Abel transform. Therefore, the temperature measurement results are not accurate by the soot pyrometry.
3. The temperature calculation in this manuscript assumes that the flame is gray? or is the soot emissivity model has been used? The author should give an explanation.

Author Response

Thank you for the feedback please see the attached for detailed responses.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

the comments have been replied, I agree to publish it!

Reviewer 2 Report

There have three papers which about measurement temperature by image processing technology. It's recommended that authors be able to cite these papers.

1. Experiments investigation on 2D distribution of soot temperature and volume fraction by image processing of visible radiation.   (DOI:10.1016/j.applthermaleng.2017.06.087)
2. Two-dimensional distributions of temperature and soot volume fraction inversed from visible flame images. (DOI: 10.1016/j.expthermflusci.2013.05.013) 
3. Experiments on Measurement of Temperature and Emissivity of Municipal Solid Waste (MSW) Combustion by Spectral Analysis and Image Processing in Visible Spectrum. (DOI10.1021/ef401374y).