Chemical Engineering Related Photo Sharing
Sunday, January 13, 2008
I'm going to share some interesting photos with you. I'll first let you see, observe and analyzed what those photos are. Just imagine and think what are the equipments or situations... It's better if you figure out what the photos shows before I provide you with some answers and brief informations at the end of the photos. If you are a student, you will find this a good learning curve, I hope so. If you already work in a processing or production plant, you may already know about these photos.
(a) What is happening?
(b) Another view on what is happening in photo a.
(c) Another clue on what is happening in photo a. If you're tired guessing, check out the answer at the end of the post.
(d) What is this?
(e) Another close up on photo d.
(f) What is this?
(g) Another clue on what is photo fAnswers & brief explanations.
Photo a: A plate heat exchanger is leaking.
Photo b: You can see traces of fluid leaking/pouring out from the bottom of the plate heat exchanger.
Photo c: An example of plate heat exchangers' plate where fluid may come out when the incoming hot and cold fluid are not balance. Or, if the gaskets are no longer functioning due to damage, torn, not perfectly attached or various other reasons.
Photo d: This is the ball which originated from a 4" 3 piece body ball valve. It is made of stainless steel SS316.
Photo e: This ball was taken out from a damaged 4" 3 piece body ball valve. This type of ball valve is imperative in processing plant. It is more reliable than a gate valve and butterfly valve but is more expansive. To learn more about ball valve, check the following links:
en.wikipedia.org/wiki/Ball_valve
flow-control.globalspec.com/learnmore/flow_control_flow_transfer/valves/ball_valves
wisegeek.com/what-is-a-ball-valve.htm
Photo f: These are sight glasses. It is use to view and observe physically the flowing fluid in a pipeline or stream.
Photo g: This photo is an example on where the sight glass will be installed. By having a sight glass, it is easier to monitor and observe the condition and physical appearance of a fluid.
To learn more about sight glass and the types available in the market, check the following links:
en.wikipedia.org/wiki/Sight_glass
visilume.co.uk/products.shtml?gclid=CNShy_rX8pACFQIsewodazLhqw
us.schott.com/special_applications/english/products/maxos.html
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Labels: Chemical Engineering, Chemical Plant, Equipments, Experience, Heat Exchanger, Leak, Learning Curve, Processing., Study
posted by Kipas Repair JB @ 2:53 PM,
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Steam and Vacuum Related Q and A
Saturday, August 11, 2007
I received 2 interesting questions at my "Vacuum Dropped Alert" post last June. I think its better for me to answer them in a new post for the benefits of others. I discussed the questions/problems with my colleague at work. I hope Mr Owais and Mr Vinay do not mind we discuss it here.
The first questions from Mr Owais (as adopted from the comment section);
"I'm working as a chemical engineer in GamaLux OleoChemical, Fat Splitting Unit.We're facing the same problem. Our main boiler is under maintenance and smaller one in progress time and again vacuum drop and our production get effected but when we don't have good vacuum then we hold the plant or lower down the feed input and product out put but the main problem is that if we lower down the product Fatty acid flow rate then it get chance to stuck in the pipeline then we have to flush the line which is more troublesome. What will u suggest me about how to solve the problem."
My respond/answer;
First of all, I need more informations in order to answer this issue. What is the design requirement of the steam for the plant to get its vacuum? This should be known from the plant manufacturer or current practice. The steam from the boiler house must be supplied as per the requirement of the plant(s). Maybe your smaller boiler do not produce the same amount of steam as your main boiler. Hence, if your plant vacuum system is fragile, slight pressure drop or fluctuation from the small boiler will trigger vacuum dropped and destroy the oil quality.
As for your fatty acid, you probably need a better insulation for the piping and / or steam tracing along the line. This will prevent blockage in the line (hindering fatty acid from solidifying). Sometimes you need jacketed steam tracing if the product have a lower melting point.
If everything above is not an issue, check your cooling water temperature condensing the steam. Is the temperature low enough as per design. Is the pressure from the cooling tower sufficient? Is the strainer nearby the pump suction blocked?
If everything above is still not an issue, when you stop your plant, conduct a complete air test to check and find any leakages in the vacuum system. I hope I answer your questions.
Example of a fire tube boiler that produces steam for general heating and vacuum system.- The second questions from Mr Vinay (as adopted from the comment section);
- "I am working in a textile plant as a maintenance engineer. My steam requirement is about 5500 kgs/hr. The main line from boiler to header is 4 inch. Can a smaller pipeline size lead to water carryover. We maintain TDS level in boiler of about 4000-4500. Our's is a water tube boiler."
First of all, I need more informations in order to answer this issue. Is it true your plant need 5,500kgs/hr steam? For me, that is very high. Or maybe your production capacity is very big that it require huge amount of steam. I'm just checking some information/facts...I fear, if you reduce the diameter of the pipeline, the flow rate of steam will be slightly affected/restricted. From my observation/experience, if the boiler deliver water carry over, and the water is still in the line (no where to escape), that means wet steam will occur. This will make the vacuum weak. Hopefully no water hammering takes place!!! That means, reducing the line would not help.
Install some steam trap along the line to eliminate water carry over. Spirax Sarco have a number of good steam traps (I'm not related to them).
I think your TDS is on the higher side. Do your water treatment chemicals work at more than 4000 ppm? Please check with your chemical supplier on this matter. For my case, we control the TDS at 2000, the most 2300ppm. This applies to any type of boiler.
I hope I gave a reasonably acceptable answer/suggestion/comment. If anybody want to further comment or discuss about those two issues, you are most welcome...
Labels: Chemical Plant, Leak, Learning Curve, Problem, Process Parameters, Processing., Steam, Study
posted by Kipas Repair JB @ 1:25 AM,
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Gaskets
Thursday, August 02, 2007
Yesterday, I attended a very interesting and informative training about gaskets. I never imagine that there are a lot to learn and explore about gaskets. After attending the training (delivered by Nipseal), my comprehension on gasket improved and I began appreciating it more. From the training, I know that there are various types and material of gaskets. Prices of gaskets vary a lot and some type of gasket is very tedious and difficult to manufactured/fabricated. Well, what is a gasket? According to Wikipedia, a gasket is a mechanical seal that fills the space between two objects, generally to prevent leakage between the two objects while under compression.
Other definitions/descriptions of gasket:
"A flexible material used to seal components together; either air-tight or water-tight" (PartSelect.com).
"Any of a wide variety of seals or packings used between matched machine parts or around pipe joints to prevent the escape of a gas or fluid" (Staffgasket.com).
Gaskets are commonly produced by cutting from sheet materials, such as gasket paper, rubber, silicone, metal, felt, fiberglass, or a plastic polymer.
Gaskets save money by allowing less precise mating surfaces on machine parts which can use a
gasket to fill irregularities. Gaskets are commonly produced by cutting from sheet materials, such as gasket paper, rubber, silicone, metal, cork, felt, fiberglass, or a plastic polymer (such as polychlorotrifluoroethylene). Gaskets for specific applications may contain asbestos. It is usually desirable that the gasket be made from a material that is to some degree compressible such that it tightly fills the space it is designed for, including any slight irregularities.
Gasket is very important in a process plant. It maintains the energy, temperature and pressure in a process system. Selecting a suitable gasket is a must because it does cost money. It is also directly related to the process temperature, pressure, type of medium (fluid or gas) and the chemical properties of the medium.
Another new knowledge that I learned is about spiral wound gasket that can withstand pressure up to 70-80 bar. It is a very interesting and carefully manufactured gasket made of stainless steel. However, I shall elaborate more about this in another post because it is deserve its own post!
OK, let me just explain about the simple/normal gasket. With reference to the left illustration, the gasket is sandwiched between flanges. The property of the gasket and correct compression/tightness allows the process system to maintains it pressure and would not allow oil or gas to leak.
The above illustration shows how a gasket is positioned and locked between those 4 bolts.
Another illustration shows how a gasket is positioned and locked between those 8 bolts.
We install/fix the correct type of gasket before connecting the pipeline with flanges.
The above photo is a very interesting one. It shows the condition of gasket after being used for some time. It is difficult to remove the gasket by bare hands because the gasket sticks very well. We need to use suitable tools to peel and remove the gasket from the flanges. Usually, flanges like this is opened during shutdown to clean/clear pipelines or vessels. After inspection, a new fresh gasket will be used. Never use a gasket twice.
Gasket is not only used between flanges. It is widely used everywhere in a process plant and in our kitchen (the refrigerator). In a plant, gasket can be found in the heat exchanger, valves, vessel man holes etc. The gasket needs to be properly maintained to ensure no upsets in the plant.
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Labels: Chemical Plant, Leak, Learning Curve, Plant Shutdown, Process Parameters
posted by Kipas Repair JB @ 10:22 PM,
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Spiral Heat Exchanger
Tuesday, June 05, 2007
In my plant, there are two small spiral heat exchangers which function as a shutdown cooler. I'm not sure what is the capacity and specifications of it. I have no experience using or operating them. But, I'm interested to learn about them.
Spiral heat exchanger differs a lot from plate heat exchanger (PHE). There are also pros and cons using spiral heat exchanger compared to PHE. From my limited experience, a spiral heat exchanger require less maintenance. There is no plates and no internal gaskets. To clean the internal part, a "cleaning in place" (CIP) is carried out using caustic solution up 60-75oC. The spiral heat exchanger is totally stainless steal solid and it is very heavy. One problem that can make a spiral heat exchanger useless (or very expansive to repair) is when the internal wall crack or leak. When this happen, the fluids entering the spiral heat exchanger will mixed and hence affect the production quality (reject!!!).
Spiral Heat Exchangers exhibit ideal heat transfer and fluid handling characteristics for a wide range of applications.
- Takes up only one sixth of the space
- Means lower costs for buildings, pumps valves and piping
- Uses 75% less pumping energy
- Provides higher K- value and a close temperature approach
- Ensures continual self-cleaning effect for maximum operating efficiency
For further references on this type of heat exchanger, check out Alfa laval and Heseco.
Example of a big spiral heat exchanger. The mass of it is about 5 tonnes.
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Labels: Equipments, Heat Exchanger, Leak, Learning Curve, Plant Shutdown
posted by Kipas Repair JB @ 11:51 PM,
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Steam Test
Tuesday, February 27, 2007
Steam test is almost similar to air test. Instead of injecting air, we injected steam into the vessels and pipelines. The reason we conduct steam test is to check for any leakages in the vessels and pipelines. However, unlike air test, steam test is easier to detect leak because steam will visibly shoot out from the leaking point when the pressure is already high (about 1.5 to 2 bars).
It is not necessary to maintain the steam pressure higher than 2 bars as it is already more than sufficient. Applying more steam will only be wasting time, energy and money. In addition to that, it will take longer time to release the steam after completing the process.
For our case, we did steam test at the beginning and at the end of the shutdown. Both were necessary (depending on the condition of the plant). We identified the leaking points and welded them from the earlier test. The final steam test was carried out to double check before plant start-up. Both steam tests have their own downside. The first one will delay cooling of vessels, because steam is hot. Therefore, upon opening the manhole, we have to allow at least 1/2 a day before entering the vessels. Another downside which applied for both earlier and later steam tests were the amount of water produced as condensate from the steam. During plant cleaning, existence of water is not really a problem. However, during plant start-up, water has to be fully drained before pumping oil into plant. Having a mixture of water and oil will create various problem including oil quality.
Labels: Leak, Plant Shutdown
posted by Kipas Repair JB @ 9:01 PM,
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Hydrocarbon Leak Detection in Cooling Water Systems
Tuesday, January 30, 2007
Hydrocarbon leaks in refineries and chemical plants can quickly cause fouling and outbreaks of microbial growth. This, in turn, results in rapid loss of heat transfer and system efficiency. Detecting, locating, and stopping these leaks as soon as possible is critical.
A hydrocarbon leak detection procedure is used to pinpoint process equipment that is leaking a gas, gasoline, or oil into a cooling water system. In the past, this testing has been a laboratory procedure and could require considerable time to obtain results. Newer test procedures can be performed in the field and provide immediate on-site results.
Samples of water from the inlet and outlet of a suspected leaking unit are collected. When an increase in hydrocarbon level is found in the outlet sample, the leaking unit has been identified.
Hydrocarbon leak detection analysis is used to pinpoint a process leak in its early stages. The longer a leak continues, the greater the possibility of equipment damage or plant shutdown.
There are two distinct issues with regard to process leaks into cooling water systems:
1. Leak Detection - determining that there is a process leak early, before gross contamination occurs
2. Leak Identification - identifying the specific heat exchanger that is leaking, preferably with a rapid, on-site or on-line test method
Labels: Cooling Tower, Leak, Problem
posted by Kipas Repair JB @ 4:39 PM,
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The Author
I’m Zaki. I used to be a project, process and chemical engineer. Few years ago I successfully became a Chartered Engineer (IChemE) and Professional Engineer (BEM). I'm now employed as a chemical engineering educator/researcher/consultant. Hope you like reading my blog. I welcome any feedback from you. My email: zaki.yz[alias]gmail.com. TQ!
