# Talk:Flue-gas stack

WikiProject Chemical and Bio Engineering (Rated C-class, Mid-importance)
This article is within the scope of WikiProject Chemical and Bio Engineering, a collaborative effort to improve the coverage of Chemical and Bio Engineering articles on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
C  This article has been rated as C-Class on the project's quality scale.
Mid  This article has been rated as Mid-importance on the project's importance scale.

## Reasons for reverting equation changes by Markus Kuhn

Markus, I can see from your User page and your Contributions page that you are very interested in ISO standards. However, Wikipedia articles are read by many, many people who don't have your intimate knowledge of those standards or of engineering units in general. In the case of the flue gas draft equation, your changes to make it unit-neutral as per ISO will make the equation prone to confusing people. Despite your labeling of the constant,C, as having units of K/m, there are many people who always use bars as their pressure unit (rather than Pascals) who will be confused. Then there are those who still use pounds/in² and degrees Fahrenheit who will also be confused. And there are the inexperienced readers who will not understand what units to use in any formula unless it is explicitly spelled out. For those reasons, I have reverted the equation to spell out all of the units. Regards, - mbeychok 15:01, 23 September 2006 (UTC)

## Pressure difference Delta P is defined incorrectly

The author states that the pressure difference ΔP (for the stack equation) is between the bottom and top of the stack. I believe that is incorrect. The pressure difference ΔP is the pressure difference between the outside air at the bottom of the stack, and the inside air at the bottom of the stack. It is this pressure difference that drives the hot air up the stack. The stack effect equation can be derived by taking a column of cold air outside the stack and a column of hot air inside the stack, and calculating the pressure difference between the cold air at bottom of the stack to hot air at bottom of stack. — Preceding unsigned comment added by 173.76.204.93 (talk) 08:13, 13 October 2013 (UTC)

## Why are there rings around chimneys?

Can anyone help with this - i have been challenged to find out and cant find it anywhere - on industrial / power plant chimneys why do they have markings around the top?

I think to stop aircraft hitting them. They use lights at night, but these aren't as effective in the day. Andrewjlockley (talk) 10:11, 10 April 2009 (UTC)

## Image

The image caption refers to GRES-2 and its (world's tallest) stack. However, it appears the picture is actually of GRES-1. Perhaps the stack visible in the background is that of GRES-2? Anyway, the caption should be changed. Muad 12:10, 14 June 2007 (UTC)

That is definitely not GRES-2, and not the tallest in the world. See the official utility web page GRES-2: the images look different! The smaller stack on that web page is that of the auxiliary oil-fired starter plant (as explained in Russian next to the image). The stack in the background (with smoke/vapor coming out) on our image must be the second stack of GRES-1, if this is indeed the GRES-1. At least half the units on it are inoperable, that may be why the stack in the forefront is not used. I am going to change the caption to GRES-1. Xenonice (talk) 19:04, 1 August 2008 (UTC)

## Move to "smokestack"?

Maybe it's just me, but "flue gas stack" sounds needlessly complicated, almost a euphemism. I've always known them as "smokestacks". Squidfryerchef (talk) 02:59, 6 July 2008 (UTC)

## No mention of electrostatic scrubbers?

This article has a section on pollution control devices, and it mentions such things as catalytic converters, but doesn't mention electrostatic precipitators. I thought pretty much every power plant had one. Oddly, even the article on scrubbers is entirely about devices that use an alkaline slurry to remove acidic gases, and has only a "see also" to the article on electrostatic precipitators. Squidfryerchef (talk) 03:08, 6 July 2008 (UTC)

Good catch! That was an oversight and I have extended the sentence to include electrostatic precipitators. But I would like to point out that this article does not have "a section on pollution control" and it does not need one. The article has a section entitled "Other Items of Interest" ... and that section briefly mentions stack gas cleanup methods only to point out that such cleanup is required for a cooling tower to function as a flue gas stack.
The intent of this article is to explain what a flue gas stack is and how it creates draft. It was not not intended to include air pollution control devices. Wikipedia already has a multitude of articles that cover that subject (Fossil fuel power plant, Air pollution, Flue gas desulfurization, etc., etc.) -mbeychok (talk) 04:17, 7 July 2008 (UTC)

## Pressure

Surely if the pressure in the stack is lower than that outside, gas would flow into the stack, not out? Is the article wrong, or am I misunderstanding something? Andrewjlockley (talk) 10:09, 10 April 2009 (UTC)

The pressure at the bottom of the chimney is lower than atmospheric, and this sucks in air. The air then helps to increase the pressure, and is heated by the stack gas. Hot air rises, and because of the increased pressure and the velocity of the stack gas, all the gas is pushed upwards towards the chimney exit. Could've worded that better but I'm sure somebody will correct me. 195.224.118.82 (talk) 09:39, 9 July 2009 (UTC)