An instrument for direct measurement of emissions: cooling tower example

Wallis, Christopher D.; Leandro, Mason D.; Chuang, Patrick Y.; Wexler, Anthony S.

doi:https://doi.org/10.5194/amt-15-2547-2022

Articles | Volume 15, issue 8

https://doi.org/10.5194/amt-15-2547-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/amt-15-2547-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 8

Research article

|

27 Apr 2022

Research article |

| 27 Apr 2022

An instrument for direct measurement of emissions: cooling tower example

Christopher D. Wallis, Mason D. Leandro, Patrick Y. Chuang, and Anthony S. Wexler

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Final revised paper (published on 27 Apr 2022)
Preprint (discussion started on 28 Sep 2021)

Interactive discussion

Status: closed

RC1:
'Comment on amt-2021-285', Anonymous Referee #1, 28 Oct 2021

[General comments]

Comment: This manuscript describes the development of an instrument package for characterizing cooling tower spray drift emissions of both wet droplets and dried aerosols. The instrument package measures the velocity, size distribution and concentration of the wet droplet emissions, as well as the mass concentration and elemental composition of the dried PM_2.5 and PM₁₀emissions. Such a package provides increased measuring accuracy and is also suited for a range of measurements. The manuscript is well structured and easy to follow. However, a few questions should be addressed and the reviewer would appreciate further discussion in the manuscript. The reviewer recommends a minor revision of this manuscript before its publication.

[Specific comments]

Comment: Line 87, please describe the methodology used by Chuang et al., 2008. It's difficult to locate it if being explained elsewhere.

Comment: Section 2.1.2, Line 99 - 110, highlighting the item number for each item, some of which have, others of which do not, such as Anemometer, IMPROVE PM2.5, etc. Consistency assists readers in recognizing.

Comment: Table 1, good information and summary, how are they calculated or are there any references cited?

Comment: Line 165, perhaps include the word “IMPROVE” in the first sentence stated in the text Line 105.

Comment: Line 163, state the model of this low-power notebook computer that was utilized.

[Technical corrections]

Comment: Line 212 “a parallel set of measurements are made adjacent to the tower” suggest changing “are” to “is”

Comment: Line 213 “IMPROVE PM2.5 and PM10 samplers is operated…” suggest changing “is” to “are”

Comment: Figure 1a, the font of item “13” is smaller than the rest of them. Keep consistency.

Comment: References “IMPROVE, 2020a. IMPROVE, 2020b. IMPROVE, 2017.” Pages are not found. The website turned out: “The IMPROVE website has recently been updated and reorganized, and many links from the old site are no longer active.”

Lastly, I’m looking forward to reading and/or reviewing the subsequent papers that detail the findings of these measurements at individual power plant cooling towers.

Citation: https://doi.org/10.5194/amt-2021-285-RC1
- AC1: 'Reply on RC1', C. D. Wallis, 10 Nov 2021
  
  Thank you for the feedback, we've found it to be very constructive. We will incorporate your suggestions into our revision.
  
  Citation: https://doi.org/10.5194/amt-2021-285-AC1
RC2:
'Comment on amt-2021-285', Anonymous Referee #2, 08 Dec 2021

The manuscript presents a method to measure aerosol emission from cooling towers using direct dried-aerosol sampling techniques, both off- and online. The authors use two sets of instruments; aloft and ground-based. The latter one is used as reference to correct for sampling losses in the aloft setup. The normalization is done using PM10 and PM2.5 passive sampling but a comparison of the APS results is missing. I suggest the auhors to provide a comparison of the size distributions obtained by APS measurements in order to improve the manuscript. The paper is well written and should be published after considering this suggestions and the following minor comments.

Minor comments:

L. 95: What would be the expanded uncertainty of the method?

L. 212: How far from the tower is the parallel set of measurements located?

Table 2: Please report standard deviations for the values shown here. Please fix the units to µg/m³

Citation: https://doi.org/10.5194/amt-2021-285-RC2
- AC2: 'Reply on RC2', C. D. Wallis, 06 Jan 2022
  
  Thank you for the comments and suggestions, we find them to be helpful. We will incorporate them into the revision of the paper. Responses to some specific questions are also below:
  The manuscript presents a method to measure aerosol emission from cooling towers using direct dried-aerosol sampling techniques, both off- and online. The authors use two sets of instruments; aloft and ground-based. The latter one is used as reference to correct for sampling losses in the aloft setup. The normalization is done using PM10 and PM2.5 passive sampling but a comparison of the APS results is missing. I suggest the auhors to provide a comparison of the size distributions obtained by APS measurements in order to improve the manuscript. The paper is well written and should be published after considering this suggestions and the following minor comments.
  We will compare APS results from the two sampling trains along with field findings in a subsequent manuscript describing dried aerosol findings.
  What would be the expanded uncertainty of the method?
  We have updated the discussion of this method to include total uncertainty.
  How far from the tower is the parallel set of measurements located?
  The exact distance from the tower to the parallel measurement varied between towers, but was approximately 100 feet (30m). Positioning of the ground-based instrument was such that it was representative of the intake of the cooling tower but avoided emissions from the ground-based generator and exhaust from the crane, and was subject to different physical layout constraints at each site. The paper has been updated to include this information.
  Table 2: Please report standard deviations for the values shown here. Please fix the units to µg/m³
  The chart shows two individual test results, so there is no standard deviation to report. We have added uncertainty for this data collection method to the table.
  
  Citation: https://doi.org/10.5194/amt-2021-285-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by C. D. Wallis on behalf of the Authors (04 Feb 2022) Author's response Manuscript

EF by Manal Becker (07 Feb 2022) Author's tracked changes

ED: Publish as is (17 Feb 2022) by Hang Su

AR by C. D. Wallis on behalf of the Authors (28 Feb 2022)

Short summary

Measuring emissions from stacks requires techniques to address a broad range of conditions and measurement challenges. Here we describe an instrument package held by a crane above a stack to characterize both wet droplet and dried aerosol emissions from cooling tower spray drift in situ. The instrument package characterizes the velocity, size distribution, and concentration of the wet droplet emissions and the mass concentration and elemental composition of the dried PM_2.5 and PM₁₀ emissions.