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ChE Plus Newsletter Volume 2, Issue 4 ChE Plus Subscriber - Click Here for a Printable Version Not a subscriber to ChE Plus? Join now for a one time fee of $34.99 USD or learn more |
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Removing dissolved oxygen from boiler feed water is absolutely necessary to protect your boiler equipment from severe corrosion. But the make-up water necessary in any boiler system inevitably contains dissolved oxygen. Oxygen can sometimes enter condensate systems as well. A good deaerator is essential to trouble-free boiler operation.
Above is a typical "older-style" boiler feed water deaerator. You'll see why I call it "older" in a moment. The theory here is relatively simple. Treated water containing dissolved oxygen is fed onto a contacting device where the water can be heated and contacted with steam which is also fed to the vessel. The steam heats the incoming treated water to around 250 °F (120 °C) and allows oxygen to escape (along with any small amount of uncondensed steam) to the atmosphere. Notice that the returning condensate is NOT contacted with the steam in this system. Some systems feed the treated water and condensate together to ensure a very low oxygen content. Other systems do not bother as the returning condensate is expected to already have a low oxygen content. You'll see that newer systems are designed to treat both sources in most cases. A next generation deaerator system from Hurst Boiler, called the Oxy-Miser, utilizes a scrubbing section to contact oxygen-rich feedwater with steam rather than the more traditional tray arrangement.
Again, you can see that both the treated boiler feed water and the condensate return are sent through the scrubbing section of the deaerator. The Oxy-Miser system is available in capacities ranging from 5,000 to 200,000 lb/h (2300 to 91000 kg/h). Below is an actual installation photo:
If you'd like to learn more about the
Oxy-Miser Deaerator from Hurst Boiler, use this link: http://www.hurstboiler.com/oxymiser.htm Most chemical processes utilizing natural gas in the U.S. were designed to be profitable assuming natural gas prices ranging from $3-4.50/MMBtu. Now, consider the fact that natural gas prices have been averaging in the range of $5-8/MMBtu. The topic of LNG (Liquefied Natural Gas) importing into the U.S. has become a main discussion point around the industry. Here's a basic idea of how importing natural gas from port tankers works:
Below is a photo of the key pieces of equipment in this process, the vaporizers:
These images are from the best paper on the
internet available on this topic. It's titled "LNG
Import Terminals". Adobe Acrobat Reader is required to view this article. Have you tried to procure a piece of chemical processing equipment lately? What part did you enjoy the most? The 10 day validity period on the proposal or the 15-40% price increase since you began your evaluation of the project's payback period? What in the world is going on with material prices? Carbon steel, stainless steel, titanium, nickel....take you pick, they're all increasing in price and in some cases they're increasing dramatically. Is China to blame? We've created an online forum for you to discuss you're findings with other engineers: Discuss material prices in the online forum Here are some good resources to check out for the latest material price indices: Two New Software Titles Available We've released two (2) brand new software titles in our online store. Ezze Corre and Oil Prop (trial available) Click on the titles below to read more about them in our online store. Metals Designations and Equivalents Distillation Column Control Design Sign up for our FREE Trade Publications. Our traffic is booming! Approximately 16,000 people around the globe receive our newsletter and nearly 80,000 unique visitors a month visit our site. See our advertising options.
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Solving
the Colebrook Equation for Friction Factors - Part 3
