http://www.cip.ukcentre.com/steam.htm
Good article on steam boiler, giving a general overview of steam boilers and associated equipment.
1. Utilization of steam
2. Steam plant operation
3. Equipment considerations
4. How to chemically treat a boiler system
5. Problems encountered in operating boilers
6. General troubleshooting of boiler water systems
Monday, September 29, 2008
Specific vs Cation Conductivity
A. Conductivity – Conductivity is the measurement of a liquid’s ability to transfer electrical current. In power plants, conductivity instruments are used to measure contaminants (consisting primarily of mineral salts) in high-purity water. Air intrusion into surface condensers, and the injection of other treatment chemicals such as ammonia, amines, etc., however, can affect conductivity. These instruments cannot differentiate between minerals and gases.
There are two types of conductivity measurements: specific and cation. Specific conductivity can detect only large amounts of contaminants. Condenser tube leaks normally start out very small, and may increase over time. For example, condensate flow may be 5,000 gpm, and the “leak” 0.1 gpm. On a volumetric basis, this is 20 ppm. Specific conductance instruments may not be able to detect this small leak unless the cooling water conductivity is very high to start.
Cation conductivity instruments pass the condensate sample through a cation (ion exchange) resin to convert cations (sodium, calcium, etc.) to the hydrogen form, producing an acidic effluent. Since acids are much more conductive than mineral salt solutions, the effective sensitivity is increased dramatically. The generally accepted lowest detection limit (LDL) is 0.05 microsiemens per centimeter (μS/cm). With such sensitivity, cation conductivity can be a very useful measurement to detect condenser tube leaks.
From: Boiler Feedwater & HRSG: A New Method for Exposing Condenser Leaks – On-Line Particle Detection - by Robert L. Bryant
Industrial WaterWorld November, 2007
Retrieve on 29-SEP-2008 from http://ww.pennnet.com/display_article/313937/64/ARTCL/none/none/1/Boiler-Feedwater-&-HRSG:-A-New-Method-for-Exposing-Condenser-Leaks-%E2%80%93-On-Line-Particle-Detection-/
There are two types of conductivity measurements: specific and cation. Specific conductivity can detect only large amounts of contaminants. Condenser tube leaks normally start out very small, and may increase over time. For example, condensate flow may be 5,000 gpm, and the “leak” 0.1 gpm. On a volumetric basis, this is 20 ppm. Specific conductance instruments may not be able to detect this small leak unless the cooling water conductivity is very high to start.
Cation conductivity instruments pass the condensate sample through a cation (ion exchange) resin to convert cations (sodium, calcium, etc.) to the hydrogen form, producing an acidic effluent. Since acids are much more conductive than mineral salt solutions, the effective sensitivity is increased dramatically. The generally accepted lowest detection limit (LDL) is 0.05 microsiemens per centimeter (μS/cm). With such sensitivity, cation conductivity can be a very useful measurement to detect condenser tube leaks.
From: Boiler Feedwater & HRSG: A New Method for Exposing Condenser Leaks – On-Line Particle Detection - by Robert L. Bryant
Industrial WaterWorld November, 2007
Retrieve on 29-SEP-2008 from http://ww.pennnet.com/display_article/313937/64/ARTCL/none/none/1/Boiler-Feedwater-&-HRSG:-A-New-Method-for-Exposing-Condenser-Leaks-%E2%80%93-On-Line-Particle-Detection-/
Thursday, September 18, 2008
ทำไมต้องกำหนด minimum velocity ในท่อ?
1. ป้องกัน corrosion ในท่อแนวนอน - ต้องการให้มี flow มากพอ จนเต็มท่อ
2. ต้นทุน - ถ้าใช้ velocity ต่ำมาก ๆ ท่อจะมีขนาดใหญ่
3. fouling ในกรณีที่ของไหลมีคุณสมบัติที่ทำให้เกิดตะไคร่
2. ต้นทุน - ถ้าใช้ velocity ต่ำมาก ๆ ท่อจะมีขนาดใหญ่
3. fouling ในกรณีที่ของไหลมีคุณสมบัติที่ทำให้เกิดตะไคร่
ทำไมต้องกำหนด maximum velocity ในท่อ?
1. noise - ยิ่ง velocity เยอะ ยิ่งเสียงดัง (โดยเฉพาะ ใน control valve)
2. pressure drop - ยิ่ง velocity เยอะ ยิ่ง pressure drop เยอะ
3. erosion - ในกรณีมีของแข็งในท่อ จะเกิด erosion ขึ้นได้ ให้พิจารณาการใช้งาน ถ้า short cycle/duration ใช้ velocity สูง ๆ ได้
4. pump suction - maximum velocity ถูกจำกัดด้วย vapor pressure
5. การใช้ check valve - ถ้าเป็น swing check ต้องมี velocity ประมาณ 12-18 fps ที่จะทำให้วาล์วเปิดเต็มที่อยู่ได้ ในขณะที่ Nozzle check ต้องการแค่ 3 fps
6. vibration - มีผลกับวาล์ว ข้อต่อต่าง ๆ จะได้รับแรง “structural force”
7. surge หรือ water hammer (ท่อพลาสติก PVC ไม่ควรใช้ velocity เกิน 5 fps เพื่อป้องกัน surge เพราะท่อพลาสติกทนความดันได้น้อยกว่าท่อเหล็ก)
จาก 1997 ASHRAE Fundamentals Handbook หน้า 33.3 : Max water velocity เพื่อลด/ป้องกัน erosion
Normal operation----Velocity
hours per year------m/s
1500 ---------------4.6
2000 ---------------4.4
3000 ---------------4.0
4000 ---------------3.7
6000 ---------------3.0
หน้าเดียวกันบอกอีกด้วยว่า velocity ประมาณ 3-5 m/s จะมีระดับเสียงอยู่ในเกณฑ์ที่ยอมรับได้สำหรับที่อยู่อาศัยและอาคารพาณิชย์
2. pressure drop - ยิ่ง velocity เยอะ ยิ่ง pressure drop เยอะ
3. erosion - ในกรณีมีของแข็งในท่อ จะเกิด erosion ขึ้นได้ ให้พิจารณาการใช้งาน ถ้า short cycle/duration ใช้ velocity สูง ๆ ได้
4. pump suction - maximum velocity ถูกจำกัดด้วย vapor pressure
5. การใช้ check valve - ถ้าเป็น swing check ต้องมี velocity ประมาณ 12-18 fps ที่จะทำให้วาล์วเปิดเต็มที่อยู่ได้ ในขณะที่ Nozzle check ต้องการแค่ 3 fps
6. vibration - มีผลกับวาล์ว ข้อต่อต่าง ๆ จะได้รับแรง “structural force”
7. surge หรือ water hammer (ท่อพลาสติก PVC ไม่ควรใช้ velocity เกิน 5 fps เพื่อป้องกัน surge เพราะท่อพลาสติกทนความดันได้น้อยกว่าท่อเหล็ก)
จาก 1997 ASHRAE Fundamentals Handbook หน้า 33.3 : Max water velocity เพื่อลด/ป้องกัน erosion
Normal operation----Velocity
hours per year------m/s
1500 ---------------4.6
2000 ---------------4.4
3000 ---------------4.0
4000 ---------------3.7
6000 ---------------3.0
หน้าเดียวกันบอกอีกด้วยว่า velocity ประมาณ 3-5 m/s จะมีระดับเสียงอยู่ในเกณฑ์ที่ยอมรับได้สำหรับที่อยู่อาศัยและอาคารพาณิชย์
Monday, April 2, 2007
Oops... Error Code 008 when logging in to Gmail
Ever since I started using Gmail, I have been having getting the error message "Oops... the system was unable to perform your operation (error code 008). Please try again in a few seconds."
It happens very often (almost every time) when I apply a label or archive my emails. I thought it was just some glitch in either my computer setting, my IE settings or whatever. I could still use my email OK, except that my inbox view does not refresh automatically (and I had to click "Inbox" link on the left to refresh the inbox).
It's a bit annoying, but I could live with it so I didn't bother to find the solution to it. However, starting a few weeks back, every time I log on to my Gmail account, I would get about a dozen of Error Code 008 messages (one stacking on the others). And I had to hit OK a dozen times before I could get to my Inbox.
Well, that's a bit too annoying to live with!! So I searched for the solution of this error, Google said it could be because of the cache on my computer. I deleted all the cache and cookies on my computer... log on to my Gmail account. There those Error Code 008 messages popping up another dozen times.
Obviously, cache wasn't the problem. And I kind of suspect that before clearing cache too, because I have another Gmail account, and I didn't get this error code 008 on that account. So there must be something wrong with "this" particular Gmail account.
I found someone suggesting to change the setting of Gmail to "Basic HTML". I couldn't follow his instruction, however, I noticed some other setting while I was trying to.
Under "General" tab in my Gmail setting, my language was set to "English (UK)", and I wasn't sure why it was set that way. My computer is always set to "English (US)", so I thought, well, that might be something I could try to change.
Once I changed it, I logged out of my Gmail. Tried to logged in again, and ta-da!! No more Error Code 008!!! I did a further experiment by changing my language back to "English (UK)", logged out, then logged in. And, again, I got a dozen Error Code 008 for a dozen times before I could see my emails.
Now I know this Error Code 008 at log in stage was caused by the language setting. But I still could not get rid of the error during applying labels or archive. However, I think I have enough progress that I could sleep OK this week!! :)
It happens very often (almost every time) when I apply a label or archive my emails. I thought it was just some glitch in either my computer setting, my IE settings or whatever. I could still use my email OK, except that my inbox view does not refresh automatically (and I had to click "Inbox" link on the left to refresh the inbox).
It's a bit annoying, but I could live with it so I didn't bother to find the solution to it. However, starting a few weeks back, every time I log on to my Gmail account, I would get about a dozen of Error Code 008 messages (one stacking on the others). And I had to hit OK a dozen times before I could get to my Inbox.
Well, that's a bit too annoying to live with!! So I searched for the solution of this error, Google said it could be because of the cache on my computer. I deleted all the cache and cookies on my computer... log on to my Gmail account. There those Error Code 008 messages popping up another dozen times.
Obviously, cache wasn't the problem. And I kind of suspect that before clearing cache too, because I have another Gmail account, and I didn't get this error code 008 on that account. So there must be something wrong with "this" particular Gmail account.
I found someone suggesting to change the setting of Gmail to "Basic HTML". I couldn't follow his instruction, however, I noticed some other setting while I was trying to.
Under "General" tab in my Gmail setting, my language was set to "English (UK)", and I wasn't sure why it was set that way. My computer is always set to "English (US)", so I thought, well, that might be something I could try to change.
Once I changed it, I logged out of my Gmail. Tried to logged in again, and ta-da!! No more Error Code 008!!! I did a further experiment by changing my language back to "English (UK)", logged out, then logged in. And, again, I got a dozen Error Code 008 for a dozen times before I could see my emails.
Now I know this Error Code 008 at log in stage was caused by the language setting. But I still could not get rid of the error during applying labels or archive. However, I think I have enough progress that I could sleep OK this week!! :)
Thursday, November 30, 2006
Dog looks at the airplane
The day I flew back to Thailand, I wore this T-shirt that has a dog printed at the front. The dog is kinda cute, but that wasn't the reason why I bought it. I bought it because of the text "dog looks at airplane" underneath the dog.
During the flight, the air-hostess asked me what did it say on my T-shirt. I pulled my shirt striaght to show her, she read but didn't seem to get it. I guess only Thais would understand it, so I explained to her.
During the flight, the air-hostess asked me what did it say on my T-shirt. I pulled my shirt striaght to show her, she read but didn't seem to get it. I guess only Thais would understand it, so I explained to her.I said it was translated from a Thai phrase (ma-hen-kraung-bin) that was used to call a guy who aimed high. For example, if a guy liked a girl who's very beautiful and sophisticated and he was definitely out of her league, we would say that this guy was "a dog looking at the airplane", becuase he would never be able to reach the plane.
The air-hostess listened, nodded, and left. I wasn't convinced that she understood my explaination, may be she was too polite to bother me further. I thought afterwards that the word "aim high" didn't sound like a proper English as it's more like a direct translation from Thai "wang- soong" (high expectation). Then I thought may be high expectation was a better term.
Thai Phrase: Ma-hen-kruang-bin (dog looks at the airplane) - someone who expects something beyond his/her status or position.
The air-hostess listened, nodded, and left. I wasn't convinced that she understood my explaination, may be she was too polite to bother me further. I thought afterwards that the word "aim high" didn't sound like a proper English as it's more like a direct translation from Thai "wang- soong" (high expectation). Then I thought may be high expectation was a better term.
Thai Phrase: Ma-hen-kruang-bin (dog looks at the airplane) - someone who expects something beyond his/her status or position.
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