technologist | 23 Mar, 2008, 21:10 |
General | (161 Reads)
When to use a centrifugal or a Positive Displacement pump (PD) is not always a clear choice. To make a good choice between these pump types it is important to understand that the two types of pumps behave very differently. By looking at the performance chart below you can see just how different they are. The centrifugal has varying flow depending on pressure or head, whereas the PD pump has more or less constant flow regardless of pressure Read It Here....
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technologist | 22 Feb, 2008, 04:37 |
General | (245 Reads)
Hot water can in fact freeze faster than cold water for a wide range of experimental conditions. This phenomenon is extremely counter- intuitive, and surprising even to most scientists, but it is in fact real. It has been seen and studied in numerous experiments. While this phenomenon has been known for centuries, and was described by Aristotle, Bacon, and Descartes, it was not introduced to the modern scientific community until 1969, by a Tanzanian high school student named Mpemba. Read More.......
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technologist | 24 Jan, 2008, 21:48 |
General | (188 Reads)
I am invariably finding many hits on cooling tower capacity & performance calculation and related queries. Therefore, I have decided to include the detailed calculation procedure in order to enable many students & process engineers who are interested in improving cooling towers performance by following these simple steps. If you have any query, kindly post them in the comments section. I’ll try my level best to answer those queries as soon as possible. First you should collect all the data as given below. Be sure that the data collected for these temperatures is most accurate because of lower absolute level of generally ~40°C average temperatures, an error of 0.5°C due to manual data collection & judgment will cause more than 1.2% error in the result at one calculation. Repeating such errors may result in cumulative errors of more than 10% in totality giving you totally absurd results. So the basic point is that collect the data on regular basis, keep a watch to have a feel of real values & then proceed Read More.....
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technologist | 04 Dec, 2007, 21:13 |
General | (435 Reads)
Have you ever faced a problem of calculating the Viscosity of a Muixture?
Most of us feel that there is no approx formula for calculating Viscosity of mixture of liquids.
Now here is a useful co-relation. Thanks to Milt, It is his effort which can be very useful for many of us. Read More...
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technologist | 26 Nov, 2007, 03:50 |
General | (324 Reads)
Compressor Curves are generally misunderstood in day-today working of process engineers and many confusions arises out of discussion among cross functional teams. This becomes more confusing in case of Recycle loop systems for example in Ammonia synthesis loop OR Ethylene oxide Synthesis Loop. Read More....
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technologist | 01 Nov, 2007, 21:51 |
General | (209 Reads)
Many forums or dicussion board / Blogs will tell you about the role of process engineers in the chemical manufacturing industry. But you may rarely find out the real technical challenges faced by a process engineer. Recently I faced some of them & then thought to write on this issue.
The most important out of several ones is the availability of CORRECT DATA.
Trackback URL: http://www.chemicalblogs.com/trackback.php?id=466
technologist | 12 Oct, 2007, 23:54 |
General | (256 Reads)
Opponents of dams have long argued against putting barriers in the natural flow of a river. Dams, they point out, prevent endangered fish from migrating, alter ecosystems, and threaten the livelihoods of local communities. Native Americans, fishing communities, and environmentalists have made these arguments in their quest to decommission four dams on Klamath River, which runs from southwest Oregon to the coast of California. But with California requiring a 25 percent reduction in the state's carbon dioxide emissions by 2020, clean energy has suddenly entered the Klamath dam debate.
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technologist | 12 Oct, 2007, 23:49 |
General | (222 Reads)
This is with reference to my earlier post on the topic.
After analysis, we found that the selection of worng type of pipe is causing typical failure problem. 
Read More
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technologist | 25 Sep, 2007, 02:37 |
General | (291 Reads)
We all face a very common problem of how to measure the performance of an inefficient pump in absence of flow meters particularly in case of cooling water pumps where usually there is no flow meter.
Based on my past experience in energy audit for last several years I found that we know the pump is not upto the mark based on its physical apperance of corrosion, leakages, sound etc. but how to prove it based on data that too when it is delivering the design head when you measure discharge & suction pressures. This is very confusing.
Read the simple method to verify the performance. You only need the performance curve originally supplied by the manufacturer.
Trackback URL: http://www.chemicalblogs.com/trackback.php?id=415
technologist | 25 Sep, 2007, 02:34 |
General | (184 Reads)
This story was sent to me by a friend & thought I should share it with you all.
An atheist professor of philosophy speaks to his class on the problem science has with God, The Almighty. He asks one of his new students to stand and.....
Prof: So you believe in God?
Student: Absolutely, sir.
Prof: Is God good?
Student: Sure.
Prof: Is God all-powerful?
Student: Yes.
Prof: My brother died of cancer even though he prayed to God to heal him. Most of us would attempt to help others who are ill. But God didn't. How is this God good then? Hmm?
(Student is silent.) Read More....
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technologist | 25 Sep, 2007, 02:29 |
General | (269 Reads)
Just found a list of compiled factors, so I wish to share it with all of you at one place. I will post others also on this as Update. Generally we find U values but not fouling factors, so it may be useful for many. Read it here....
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technologist | 25 Aug, 2007, 04:07 |
General | (394 Reads)
We have a shell & tube heat exchanger as feed preheater in our glycol ether acetate plant where mixed feed is preheated to ~130-140°C using steam on shell side. It has failed recently & we observed few strange things. Read More....
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technologist | 17 Aug, 2007, 21:06 |
General | (393 Reads)
Brazil pioneered the use of Ethanol as a blend to gasoline for fuel use in commercial & public transport sector. Since then the science community is trying to identify alternative fuel which is easier to use, more efficient, cost effective & bla..bla..bla.......
Trackback URL: http://www.chemicalblogs.com/trackback.php?id=361
technologist | 15 Aug, 2007, 21:41 |
General | (377 Reads)
About 100 billion cubic meters of natural gas are burned off or simply vented at remote oil rigs and refineries that are not connected by pipelines. The practice wastes a precious fuel and pumps methane, a potent greenhouse gas, into the atmosphere. Technologies for compressing or liquefying natural gas in order to transport it are expensive and only make sense at large oil fields. So, researchers have been looking for viable technologies to convert the natural gas found at small, isolated oil fields into compounds that are easier to transport and distribute.
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technologist | 01 Aug, 2007, 20:58 |
General | (1297 Reads)
How much is the typical coal fired boiler efficiency? Probably the best operating boiler can achieve ~80% or +/-2%. Historically, boiler efficiency has been limited due to the minimum temperature allowed for the auxiliary equipment. Heat lost up the stack was in exchange for keeping the flue gas temperature above the water vapor dew point to protect the air heater or economizer from acid corrosion. If water vapor was allowed to condense out, rapid deterioration, due to acid corrosion, of the outlet duct and stack would also occur.
The contribution of dry flue gas is ~9-12% & ~5-8% due to presence of humidity & water in combustion products. The reason is that the flue gas temperature (generally 170 - 200°C) is limited by dew point to avoid condensation of downstream exchangers.
With the development of CHX™ condensing heat exchangers, boiler efficiency can now approach 90%. Approximately 1% gain in boiler efficiency can be expected for every 20° C reduction in flue gas stack temperature. Therefore if we can lower it to ~90°C or so, we can practically recover more heat with total thermal efficiency increase from 80% to ~88% or so.
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technologist | 26 Jul, 2007, 05:15 |
General | (275 Reads)
Life-cycle cost analysis (LCCA) is a method for assessing the total cost of facility ownership. It takes into account all costs of acquiring, owning, and disposing of a project. LCCA is especially useful when project alternatives that fulfill the same performance requirements, but differ with respect to initial costs and operating costs, have to be compared in order to select the one that maximizes net savings. For example, LCCA will help determine whether the incorporation of a good HVAC or glazing system, which may increase initial cost but result in dramatically reduced operating and maintenance costs, is cost-effective or not. LCCA is not useful for budget allocation. Lowest life-cycle cost (LCC) is the most straightforward and easy-to-interpret measure of economic evaluation. Some other commonly used measures are Net Savings (or Net Benefits), Savings-to-Investment Ratio (or Savings Benefit-to-Cost Ratio), Internal Rate of Return, and Payback Period. They are consistent with the Lowest LCC measure of evaluation if they use the same parameters and length of study period. The approach to making cost-effective choices for projects can be quite similar. Read More....
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technologist | 26 Jul, 2007, 05:09 |
General | (228 Reads)
System Background In the concentrator section of phosphoric acid plant, weak phosphoric acid is concentrated by evaporation in graphite made evaporator. This is normally operated under vacuum & ~88°C temperature due to highly corrosive nature of phosphoric acid (PA). Over a period of time, the tubes of this exchanger require cleaning for removal of deposits & fouling material. This is a normal practice in both plants i.e. PAP-I & PAP-II. Read More....
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technologist | 26 Jul, 2007, 05:08 |
General | (225 Reads)
ASDs are ideally suited for variable-torque loads from centrifugal pumps, fans, and blowers when the system load requirements (head, flow, or both) vary with time. Conditions that tend to make ASDs cost-effective include the following: High horsepower (greater than 15 to 30 hp)—the higher the pump horsepower, the more cost-effective the ASD application. Load type—Centrifugal loads with variable-torque requirements (such as centrifugal pumps or fans) have the greatest potential for energy savings. ASDs can be cost-effective on positive displacement pumps, but the savings will generally not be as great as with centrifugal loads. Read More....
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technologist | 20 Jul, 2007, 02:15 |
General | (301 Reads)
By 2010 purchases of centrifugal pumps in China will rise to over $5 billion, surpassing the U.S., whose purchases are projected at under $4.9 billion. These are the latest forecasts in Pumps:
The top ten purchasers in 2010 will include primarily Asian and European countries:
2010 Projected Centrifugal Pump Purchases ($ Millions)
China: 5,149
United States: 4,886
Japan: 1,595
India: 1,092
Trackback URL: http://www.chemicalblogs.com/trackback.php?id=320
technologist | 20 Jul, 2007, 02:13 |
General | (153 Reads)
Today I was reading a question regarding reduction in losses from large storage tanks for solvents. The existing system was having ~300 tanks at set pressure of 200 mmWC with vent condensers. 10°C chilled water is used for chilling in those vent condensers with vent setting of non condensable at 300 mmWC.
Few experts on the forum suggested that use 2-3°C chilled water to reduce the vent losses and properly size the condensers for improved heat transfer.
Any comment……………Before I proceed…….If U really have different things in mind let me know & I offer a job in technical services department of my company. (This offer is for readers from India only for Chemical Engineering Graduates with 0 to 8 years experience)I will post my solution which I have implemented here cost effectively on Monday on my main blog http://profmaster.blogspot.com ___________________________________________________________________ Disclaimer: I do not guarantee the job offer unless the candidate qualifies other parameters of selection procedure.
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technologist | 17 Jul, 2007, 22:25 |
General | (160 Reads)
Today I was reading a very interesting discussion on one of the famous forums at Cheresources. This was really interesting. Newcomers should learn these useful things to avoid confusing states and hence it enables them for better decision making skills. Why there is a difference in the measured suction flow & discharge flow of a blower (No Spill Back or antisurge or recycle is there). She got Suction flow as 62000 Nm3/Hr and discharge as 48000. How it is possible?????????? Read More......
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technologist | 06 Jul, 2007, 23:26 |
General | (222 Reads)
In the literature surface tensions of liquids are usually given at one temperature only (often 15 or 20 °C). As the temperature is raised, the surface tension decreases and becomes zero at the critical point. Based on this observation the surface tension at temperature T2 can be estimated for most liquids from the following simple equation if surface tension at another temperature T1 and critical temperature Tc of the liquid are known Read More....
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technologist | 06 Jul, 2007, 21:38 |
General | (131 Reads)
Generally almost every industry face the problem of failures / corrosion / pitting in compressors internals due to presence of mainly mositure while handling any gas coming out through a wet system or air. The Reason
Read More........
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technologist | 05 Jul, 2007, 23:14 |
General | (136 Reads)
Tray Towers For ideal mixtures, relative volatility can be taken as the ratio of pure component vapor pressures. Tower operating pressure is most often determined by the cooling medium in condenser or the maximum allowable re-boiler temperature to avoid degradation of the process fluid. For sequencing columns:
Read More......
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technologist | 04 Jul, 2007, 01:05 |
General | (127 Reads)
"One such misperception that has managed to persist in the public domain over the last few years is the perceived carcinogenic risk posed by sodium lauryl sulfate, a chemical commonly found in beauty care products. Despite strong evidence to the contrary, including an article published by the American Cancer Society definitively positing no link... Read More......
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technologist | 04 Jul, 2007, 01:04 |
General | (126 Reads)
This is happening in China today. This has happened in China as far as I know for at least 10-20+ years. I'm surprised that the media is only paying attention to this story now. I know it sounds rather paranoid, but it IS possible to avoid products 'Made in China'. Even towels made in China can expose a person to illegal chemicals! Read More.....
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technologist | 04 Jul, 2007, 01:01 |
General | (153 Reads)
Featured today in Wikipedia's newest pages, Methionylalanylthreonyl...leucine is a chemical name for enaptin, a nuclear envelope protein found in human myocytes and synapses, which is made up of 8,797 amino acids. Hope this won't be a dupe, this will be hard to search for. Read Full Name........
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technologist | 01 Jul, 2007, 21:40 |
General | (129 Reads)
A machine is a mechanical device with moving parts that helps to do some useful action, usually work. Machines may be just mechanical (pulley-and-belt), hydraulic (water wheel, the earliest engine), pneumatic (windmill), electrical (electric motor, the most common nowadays), chemical (fuel cell), or thermal.
I am restricting it to devices that converts heat to work (heat engine), and to devices that pump low-temperature energy to high-temperature energy (by using some source of exergy), all working cyclically. The heat-pumping machine may be intended to produce cold (refrigerator), or to produce heat (heat pump), or both at the same time (refrigerator with heat recovery, or heat pump). Heat EnginesDefining it? Want to read more......
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technologist | 29 Jun, 2007, 22:26 |
General | (248 Reads)
Phrases for Successful Life
- Think – there must be a better way.
- Problems are only solutions in disguise.
- Learn by Listening ….. Understand by reflecting.
- Speech is better but quiet is intelligence.
- There is no right way to do something wrong.
- Making excuse does not hurt anybody, but your self.
- A liar is not believed when he speaks the truth.
- A man’s reach should not exceed his grasp.
- Strong convictions precede great actions.
- Arrogance is the quicksand of success.
- The greatest loss is the loss of self – confidence.
- Learn to say " NO ".
- Success has made failures of many man.
- Experience is one thing you can’t get for nothing.
- Organise Yourself well to have more time to do things you love to do.
- You cannot be anything if you want to be everything.
- Don’t start something which you cannot stop.
- Of all the things you wear, your expression is the most important.
- There’s plenty of room at the top, but there’s no room to sit down.
- Admitting you’re wrong is a modest way showing you’ve grown a little wiser.
- Ships are safer in the harbour, but they are not meant for that purpose.
- Some people pay so much attention to their reputation that they loss their character.
- When confessed, the sin becomes less since it becomes the truth.
- Even if you’re on the right track, you’ll get run over if you just sit there.
- At the start of your career, what you learn is more important that what you earn.
- There is no indigestion worse than that which comes from having to eat your own wards.
- A vacation should be just long enough for the boss to miss you and not long enough for him to discover how well he can get along without you.
- The fire you kindle for your enemy burns yourself more than him.
- Either I will find a way or make one.
- If it were not for the rock in the bed , the stream would have no song.
- There are two ways of spreading light: to be the candle or the mirror that reflects it.
- Always tell yourself: The difference between running a business and running a business is “I”.
- A wise man is one who forgets the fault of others, but always remembers his own.
- Cut your social functions where your substitute will be equally good and no one will miss you.
- It is not only machinery that becomes obsolete. One has to guard against obsolescence of the mind.
- Many a live wire would be dead except for his connections.
- Success isn’t the opposite of failure. A runner may come is last , but if he beats his Record , he succeeds.
- A man is not hurt so much by what happens as by his opinion of what has happened.
- Other men see things as they are and ask, “why”. I see things that never were and ask,
“Why not?”.
- A fundamental requirement for success: humility.
- Dare to dream –dare to try-dare to fail- dare to success.
- Watch your thoughts- they become your words.
- Watch your words- they become your actions.
- Watch your action- they become your habits.
- Watch your habits- they become your character.
- Don’t be afraid to ask dumb questions: they’re more easily handled than dumb mistakes.
- Why are we so polite to those we don’t know, and so rude and crude to those we love?.
- When all of us think alike, no one is thinking.
- When the blind man carries the lame, both go forward.
- Praise in public; reprimand in private.
(More)
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technologist | 29 Jun, 2007, 02:46 |
General | (194 Reads)
Can anybody suggest a better method for Fusel oil dehydration? I am able to achieve only 1.2% Moisture at the outlet of molecular sieves UOP-3A-1/16. I need to reduce it below 0.5%.
Trackback URL: http://www.chemicalblogs.com/trackback.php?id=256
technologist | 05 Jun, 2007, 23:20 |
General | (146 Reads)
My Company’s Message on World Environment Day
1. I will boil only the water I need, rather than filling the kettle every time.
If you boil a full kettle three times a day you’ll raise carbon dioxide emissions by 52kg a year. It takes two trees to absorb that amount. If you only boil the water you need each time, you’ll save energy and reduce your carbon dioxide emissions by more than 7kg a year.
· Carbon dioxide is a greenhouse gas, which contributes to climate change. We need to reduce the amount of carbon dioxide we release to limit the effects of climate change.
· Although trees can be planted to absorb some of this carbon dioxide, we really need to use up less energy in the first place.
2. I will replace two light bulbs in my house with energy saving versions.
Over one year, it would take 13 trees to absorb the 40kg of carbon dioxide you would have emitted into the air.
· The release of carbon dioxide into the atmosphere, caused by the burning of fossil fuels, contributes to climate change. We are experiencing more floods and droughts, and wildlife and plants are also affected.
· Countries that have ratified the Kyoto Protocol must reduce their carbon dioxide emissions.
· Reducing the amount of electricity we use will mean that less fuel is burned for the generators that supply it. Doing this will also save you money. (More)
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