Since I have written my experience visiting a boiler manufacturing company recently, I think it is good if I follow up with another article related to boiler. This time, it is about the importance of boiler water treatment chemicals. I remembered monitoring the boiler man blended and poured some chemicals (from Nalco) to be injected into the boilers.
Do you know that like cooling tower, a boiler also requires chemical treatment for various reasons. When I was a process engineer, I got the opportunity to learn about the chemical water treatments for utility boiler and cooling tower. There are various chemicals with specific functions. The chemicals, which I will explain below will imperatively preserve the life of a utility boiler (in this case a low pressure boiler). A low pressure boiler in this case is one which is less then 200 psi. We shall look upon several chemical parameters, namelu the amines, alkalinity, sulfites and phosphates or polymers of the boiler water.
Amines are used to increase the condensate pH to a range of 7.8 to 8.7. When generating steam, carbonic acid forms and as a result your steam pH is low. Amines are volatile and when introduced into the steam header or boiler water, amines will increase the condensate pH. A low pH will lead to excessive condensate pipe corrosion.
Alkalinity is used to increase the boiler water pH to above 10.5. This serves three purposes. pH above 10.5 will decrease your overall corrosion rates, it will keep a 3:1 ratio of total alkalinity to silica, and it allows the polymer to react with calcium. A 3:1 ratio keeps silica from plating in the boiler. A low pH will result in an over general corrosion appearance on your boiler tubes.
Sulfites are used to remove any dissolved oxygen from the water. Dissolved oxygen enters the boiler in make up water or as air is sucked into the system. Dissolved oxygen is extremely corrosive to your tubes and localized pits will form, ultimately resulting in premature tube failure. Maintain a 20 to 40 ppm residual of sulfite in your boiler water.
Phosphates and polymers are used to react with any calcium in the water. The polymer attaches itself to the calcium. The polymer and calcium then is able to exit the boiler through the surface or bottom blowdown. Phosphate reacts with the calcium and sinks the calcium to the bottom of the boiler. When using phosphates you must perform boiler blowdown daily to release the phosphate and calcium. Failure to use a polymer or phosphate will result in calcium build up on the tubes or as some call it boiler scale. This will decrease the over boiler efficiency and will drastically increase your fuel cost.
It is vital to note that water expands 100,000 times when it change from a liquid to vapor phase. A typical home water boiler 30 gallon system has enough energy to throw a 2,000 pound car over 100 feet in the air if catastrophically failed.
First Image credited to: www.johnstonboiler.com. Second Image credited to http://www.indiamart.com (Example of Nalco Chemical for boiler water treatment).
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Last Friday, I was supposed to run my experiment. I had made the tedious preparation a day earlier so that the only think I need to do on Friday is to just start the experiment.
So, what happen on Friday? I connected my online data logger to my laptop. I heat up the heating tape gradually. I switched on the online graph monitoring in the data logger software to monitor the temperature profile of each thermocouples fixed in several locations in my experimental rig. I saw the temperature increase for the heating tape thermocouple. However, the thermocouple temperature in the reactor did not raise (after I switched on my turbular furnace heating). This was strange. All this while, everything it's OK. So, it's trouble shooting time. I looked at the tubular furnace temperature display. To my surprise the temperature which I set to be 500oC is still maintained at 29oC. Oh my God... Is the tubular furnace spoil? I have just used it yesterday and it was just fine.
Troubleshooting the tubular furnace.
I turn off the helium gas from entering my reactor. I conditioned the GC. I then checked what's wrong with my tubular furnace. I attempted switching it on and off as well as changed the power supply socket. With the help of Mahadhir (my Ph.D colleague), we tried to play around with the temperature control display and investigated the setting and/or timer. Who knows this might be the reason the tubular furnace cannot heat up. Mahadhir also searched for the manual of this Carbolite tubular furnace and gave it to me. I spent quite some time digesting the information in the manual and try to relate it to the problem. By this time I already know that my Friday allocation for experiment is over. Worse case scenario is I have to spend another whole day to transfer my furnace (if it is spoil) with a spare furnace. That will definitely take one days work to do. We tried many things which also include the possibility of heater or filament spoil. However, deep in my heart, I believe that there must be a simple problem and a simple solution. But then, I cannot yet figure it out.
Accidental trouble shooting discovery I almost get fed up and nearly decided to call for Carbolite engineer to come to see what is the problem. I sat on my tiny work station in the lab room. I look at my experimental rig from a distance (actually it is not that far - only about 1 meter). I wanted to see the overview of the problem and see if there is some possible solution. Then I noticed something!!!
I found that my tubular furnace was not closed and double clipped on. Oh my God... Maybe this was the culprit. I did not even close the furnace and decided to heat it up. Immediately I close the tubular furnace and clip them. I turned on the furnace heating and off it goes. The temperature increased. So, that was the thing. It was a silly mistake and a very simple solution. I just did not close the tubular reactor.
Morale of the story
I learn my lesson that day. I need to be more careful when running the experiment. It was my first silly mistake after many times running similar experiment. I also don't know why that happen. It must slipped my mind. In addition, I can also know another that the furnace heating would not turn on if it is not properly close. It took me 1 whole day to experience this... Haha..what a day...
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Once upon a time in the Chemical Reaction Engineering Research Laboratory
On a sweet Thursday afternoon (today) when I just started my experiment, a sudden power failure occurred without warning. I was actually in the toilet when the power cut off took place. My wife called and asked, "Do you have electricity there in the lab?". I answered, "We have power here in the lab and I just started my experiment". Then 2 lab assistants walk out from the polymer lab (which is next to the reaction engineering lab) and informed me that the power failure just happened. I was surprised.
Immediately I ran into the lab and discovered that the lab black out. Oh my God!!! This is not good. It's not really about my experiment. It's the Gas Chromatography (GC) which I'm more worried about. The GC is such an important equipment for me and the rest of the students as we use it to identify and quantify our products from the reactor. The GC is very sensitive and frequent power cut-off can jeopardize the equipment and interrupt our research activities. Repairing the GC cost huge amount of money and with limited research budget, we need to do everything to avoid the GC from malfunctioning.
After about 15 to 20 minutes the electrical power resumed. Thank God. I switched it on. I then checked the GC and its PC hoping that nothing will go wrong. When the power failure occurred just now, the oven temperature (of the GC) was 250oC. The standard operating procedure to switch off the GC is when the oven temperature is below 40oC. Sudden GC shut down is not recommended at all. It is strictly a big NO. Luckily the GC works well and nothing seems to be wrong. I restarted my experiment and completed it 3 hours later.
Power Failure in the Plant
The incident reminded me on the power failure that once in a while also occurred in the physical refinery plant I worked in several years ago. Such unavoidable power cut-off from the Electricity Company will firstly trigger chaos within the control room and the entire plant. The supervisor, shift leader and plant operators have to act fast to close all main valves manually from various sections. The flow, temperature and pressure from numerous unit operation equipment such as Niagara filter (filter leaves), deodoriser, packed column, heat exchanger need to be controlled until power resumed. The huge 3000 tonnes per day plant can only be minimally controlled via the PLC which was temporarily powered with UPS (uninterupted power supply) - which provided a few minutes power back up.
Secondly, the power cut off will result in substantial lost and I have to assess and make report about it. Even a milisecond power failure will result in vacuum drop in the plant in result to oil rejection (due to quality off-spec). That also will cost massive lost to the company.
What can we do?
As for my case, in the lab... nothing much can be done. I rest my faith to the God. It's good to install UPS for the GC. If UPS is the answer, then we must have 4 UPS unit in the lab as there are all together 3 GC's and 1 GCMS. However, having UPS alone will not entirely protect this expansive machines. For me, the power company (electricity supplier) must be responsible in providing smooth and reliable power for us (the customers). They should pay all the damage and losses that hit us. Maybe this does not sound like an engineer's solution...
Other option?
A more interesting option is to create and manage our own power system...but can we do it with our resources? I'm referring to solar, wind and frequency (Tesla) energy. I would love to develop one of this power sources AFTER I complete my study. I'll try and do it at my home first... :)
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Have you downloaded my free "Choosing Alternative Fuel" Ebook? If not, then please download it here. It's Free and on top of getting the free ebook, you'll get eCourse on Alternative Fuel. It's a good and easy way to add more valuable information to yourself. Image #1 credited to: http://www.wkow.com/Global/story.asp?S=14691294&clienttype=printable Image #2 credited to: http://www.msnbc.msn.com/id/42761336/ns/us_news-life/t/refinery-warnings-way-life-texas-city/
I'm now in my 4th semester of my Ph.D studies. I will be lying if I say that doing Ph.D is easy. It's not as easy as that. I told my wife few months ago that preparing the project report for my Institution Engineers Malaysia (IEM) interview (to be a professional engineer) was tougher than doing my Ph.D. I'm wrong!!! Maybe that time, I was not really focus on my Ph.D. But now, as I'm more focus with my studies, I am well aware that completing this study is not as easy as it seems to be. It is so tough. Ask anybody who successfully completed their Ph.D... Nobody says it is easy.
Suddenly I felt time is very limited. I'm beginning to feel the pressure. I have more or less one year to complete my studies. I need to start working on my experiments. My experimental rig is fine and I believe it will be ok as I already tested it several times. The only concern for me is the quartz reactor that is brittle in nature. I need to keep sufficient stock of it. In addition, I also need to ensure my other equipments and consumables have spare as well. When talking about the experimentation work, the Gas Chromatography (GC) should also be in perfect condition for me and my Iranian colleague (Maryam) to analyze our products. The GC is the basically the heart of the study besides the rig reactor and process. I'm going to start my experimental work tomorrow officially and I hope everything will be fine... (Need to pray a lot!!!) OK ...enough about the experimental work.
Journal Paper... This is another thing hunting my back and consuming a huge chunk of my time. I have a draft prepared and submitted to 2 reputed publishers only to see on both occasions it got rejected for funny reasons (the first one) and out of scope reason (the second one). I admit that I felt miserable being rejected just like that. Well... I need to bounce back and fight to improve my draft paper and then send it again to other journal.
Thermodynamic modeling... Yeah...not only experimental work, I also need to work on the thermodynamic modeling of my catalytic reaction. This is quite interesting but at the same time it is my weakest part. I'm slowly working on this section and I hope I can complete this study in the next 2 months... (also, I need to pray to God a lot on this). I'm receiving some help from Maryam on this. She has been helping me when I got confuse and lost.
There are certainly a lot more to share about my research journey as a Ph.D student. I think I should reserve the rest for future sharing. For the time being, I just need to focus on my study for a while. Wish me luck... :)
Before ending... I would like to thank my other half of her undivided support for me. It is good to have a partner who is also in the same chemical engineering field. She understood what I'm doing and at the same time provided me precious input and ideas.
Also, my other colleague in the lab... All of you are great...haha...especially Emm2020...who has been next door to me in the lab...Let's finish this together!!!
p/s: Sorry if this post is not of any benefit to you guys. I just need to vent off some tense in me.
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While many of the fossil fuels continue to be in short demand in every corner of the world, people including governments and individuals concerned with the environment are starting to make the rest of us more aware, that these supplies will simply be gone at some point.
Many concerned people and numerous governments are looking for ways to utilize renewable energy and how this source of energy really will work most effectively.
Fossil fuels are also responsible for many of the biggest problems with the environment.
There have been many studies that link the state of the environment with the use of fossil fuels. Global warming is one of the biggest problems we are facing and both human and animals are impacted by changing weather patterns. The earth is getting hotter and this is being experienced in many places. Wild weather like hurricanes and severe droughts are among the serious consequences of global warming.
You can find a great deal of education in the movie 'An Inconvenient Truth' on the damage that global warming is causing. Normally you can find this video at any video /DVD rental location or movie download. This movie is a great surprise and you may find that this can change the way you live, because hopefully you will appreciate that a green power source must be something that we all will eventually need to incorporate into your own homes.
Right now there are many small changes you can make that can really add up.
A big advantage of most renewable energy sources is that they help to reduce the carbon footprint that each of us is leaving. Solar power, geothermal energy and wind power are some examples of how we can use clean energy sources, and this can help us to be on the leading edge of this growing movement.
Jobs in the United States are created when more people use alternative power sources and these are jobs that are unlikely to leave the US. Many of the positions available for these jobs will have a great pay base as well as benefits.
There are tax credits that are being provided and this is a major benefit provided to help people begin using green energy. This and other incentive programs are starting to make it easier for many more people to afford renewable energy programs. Some of the tax cuts give the consumer up to 30 percent of their solar installation and this is valuable for both commercial and residential consumers.
When alternative energy is affordable for all, more consumers will make this change in their home and begin using green energy technology, to help lessen the impact of global warming. Those who use renewable energy are likely to spread the word about living a greener life and this can help entire communities.
An environmentally sound community can help and guide others on how to be the most efficient in daily life. Getting guides and policies in place can help other people find and stick to a green power system that will cut down on pollution and serious environmental damage to our planet.
You can start with National Geographic. They provide a great guide called the "Green Guide". It contains solid information that someone can use to live their best green life. If your city is not already listed in this guide -- get your city listed.
People could write for quite some time about the advantages of renewable energy. However, you may also want to know about some disadvantages of renewable energy. The major disadvantage is of course the cost of any alternative power source. It is still too much of an expense for many consumers. So many are waiting for the costs to lower, because the $20,000 needed for a PV solar system means it's probably not available for many consumers.
This article is contributed by Alice Shaw. He is an ardent promoter of green living and environmental protection. If you are itching to learn more about alternative energy, you are welcome to visit his site: http://ardentgreenliving.com. You will get more green energy info.
To guess post in this blog, please contact me. You are welcome to do so to share ideas, information, experience and others related to chemical engineering industry. I look forward to receive your article... :)
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Just to share some info / news that was delivered to my mailbox by PlantServices.com. It's actually a webminar (web seminar) that you can enjoy from the comfort of your home / office to learn about how to profit from ultrasound steam system inspection.
From the brief information provided, it mentioned how we can use ultrasound to inspect steam traps and valves which are very critical and important in a processing plant. I remembered how crucial the steam traps were when i was working in a production plant before. Whenever some steam traps fail to function and when the boiler unintentionally sent us wet steam, our vacuum pressure will drop and hence disrupt our product quality. We were forced to regularly monitor all steam traps in our 7 storey plant and maintain a checklist. Once in a while, i personally checked some of the steam traps using my bare hands.
I guess that's enough for my rambling. What I wanted to highlight here is actually the webminar organized by Plantservices.com. If you want to learn about it register yourself for the program. I don't think I can make it there due to other commitments. Read the rest of the information....
Sponsored by: UE Systems Content type: Webcast Date: Thursday, September 25, 2008 Time: 12 PM ET/9 AM PT Length: 60 minutes
This tutorial will demonstrate how to conduct an ultrasound steam trap and valve survey. Viewers will learn the basics of ultrasound technology followed by details, including sound samples of various steam traps in good and in failure conditions. Strategies for effective trap and valve survey preparation and methods of recording, analyzing and reporting results will be included, as well as how effective steam trap inspections help conserve energy and increase profitability!
Featured Speaker: Douglas Waetjen - UE Systems, Inc. Mr. Waetjen has been involved with ultrasound technology since 1986. He has lectured about the technology worldwide, written numerous technical articles, and has been instrumental in the program implementation of ultrasound for hundreds of companies. Mr. Waetjen is an active member of the Society for Maintenance and Reliability Professionals (SMRP) and is chairman of the Supplier Relations Committee for this organization. As a certified Level III, Mr. Waetjen teaches Ultrasound Level I and Level II courses. In addition to his efforts to educate and lecture, Mr. Waetjen is the director of worldwide sales for UE Systems, Inc.
In actuator valve engineering and design, it is essential for engineers, designers, and manufacturers to fully understand the aspects and processes of using this particular product that would eventually help build effective engineering designs in a safe and efficient manner.
One of the most significant products of the company would be the actuators. To make this technical term simpler, an actuator is a device that transforms or converts energy into motion. Also applied as a force, an actuator usually is a mechanical apparatus that takes energy, normally constructed by liquid, air, or electricity, and converts that into a specific kind of motion. This motion can relate to anything from clamping, blocking, to ejecting. These actuators are normally used in industrial applications or in manufacturing, and may also be used in different objects such as motors, switches, valves, and pumps.
From all the actuators available in the market, the most common type would be the ones that are powered by the air, also known as the air cylinder or the pneumatic cylinder. These air cylinders are air tight, usually made out of metal, which uses the energy of compressed air in order to move a piston. In addition, air cylinders are usually used in assembly processes and in manufacturing. On the other hand, grippers, normally used in robotics, use actuators powered by compressed air in order to work similar to the human touch.
Electricity or hydraulics can be a source of power for actuators. Much like there are air cylinders, there are also electric cylinders and hydraulic cylinders where the cylinder converts electricity or hydraulics into motion, and hydraulic cylinders are often used in several types of automobiles. Most of the actuators available have more than one type of power source. For example, solenoid valves can have the ability to be powered by both electricity and air. Electricity powers the solenoid, and the solenoid, powered by air, actuates the valve. Another option for this would be that the solenoid can be powered by both electricity and the hydraulics.
Whether in a linear motion, a rotary motion, or in an oscillatory motion, actuators can still be used, that is if they can create the motion with only one direction, in a circular motion, or in an opposite direction at normal intervals. Hydraulic and air cylinders can also be classified as single acting, which means that the energy source that justifies the movement in one direction, and that a certain spring is used for the other direction. Having these interchanged, these cylinders can act as double as an acting cylinder, which means that the energy is used in two different directions. Even if actuators are usually explained in terms of mechanical implements, muscles are often given as an example of an actuator. Energy, which is created by eating carbohydrates, is converted by the muscle, which in this case would be the actuator, and transform it into motion, such as playing basketball.
The above article was authored by Christel Lumabas who is part of MEA Inc. team. MEA Inc is a world leading organization that is composed of designers, engineers and manufacturers of valves and actuator including butterfly valve, valve actuators, diverter valve, linear actuator, hydraulic check valve and electric actuator for mechanical and electrical automation systems worldwide. For more information check out http://www.meaincorporated.com.
For better comprehension, I include some photos to better illustrate the actuators:
Actuator Diagram - photo adopted from Spirax Sarco
Actuator (topside) connected to one piece ball valve - Image adopted from Randex.
Similar to the latter image, this actuator (topside) is also connected to a one piece ball valve - Image adopted from Ferret.
I just received an interesting email (thanks Mr. Ray for forwarding it to me) mentioning about a special "Volume Potable Water and Power Production" product. It is believed that this product will be of interest to World Vision as it provides clean potable water as a by-product of electrical power generation, both of which are core fundamentals to health issues for the developing world. I believe, a lot more parties will be interested with such a brilliant revolutionary product like this.
Doxford Power Ltd. (DPL), a company based in UK, produces a 10MWe power station equipment or power stations complete on a supply or BOO (Build, Own and Operate) basis. These power stations are significantly different to current (fossil and alternative) power stations in that their primary fuel is derived from two sources, Biomass (Jatropha Curcas, Rapeseed, Palm oil etc) or waste (household or industrial). With that, the product has no reliance on fossil fuels, the chance for a developing country to meet its current and future energy demands from domestic agribusiness and a waste management solution which can be run in parallel to the agribusiness which can utilize what is normally sent to landfill sites as EfW (energy for waste).
DPL owns and utilizes a second technology called a Powereau Unit which drives considerable efficiencies into standard heat engines (generators and gas turbines) and also the DPL power units. A by-product of this intercooler technology is water, and it produce lots of it. A 10MWe power station will require approximately 25,000 tonnes of biomass oil per month but will produce as a by-product in excess of 100,000 tonnes of water per month and more in humid conditions. This water alone justifies the fuel source.
Fuel Source
The DPL 10MWe power plant can utilize Jatropha Curcas plantations to supply 100% renewable and sustainable fuel supply. The berry crop has the oil removed via crushing and filtration with the waste being made into briquettes for domestic heating and cooking use (thus avoiding cutting further trees) One key issue here is sustainable employment. One DPL power plant will require 2000 hectares of land on average to run every year if Jatropha Curcas is the crop of choice. This provides employment at usually a higher standard than current farmers receive of one job per hectare.
The core infrastructure resources for world health are water and power. This DPL power plant provides both of these and whats more, it can commercially reduce current power production costs.
It seems that this is a superb product and the company has began the business development for it. I understand that the marketing material for this product is being processed now. Hence, what you are seeing (from the power point slide presentation) is the core management marketing pre-graphic designers and is not the final professional presentation yet. The product will only be available from April 2008 onwards.
I tried to get further in depth information from the company's website; Doxfordpower.com, however, it could not be opened. I hope the problem can be rectified and interested parties can refer to it for more information.
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 f
Answers & 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.
...Finally we came out with a very risky idea but can solve the problem faster. We have to maintain a slight vacuum inside the buffer tank just to hold the oil from pouring out of the leaking hole. We must attain the right balance i.e. to avoid oil from coming out of the vessel so that welding can be done; and to avoid spark from entering the vessel to avoid fire. We gathered enough manpower to execute and monitor the job.
The welding job runs smooth. Due to lack of time, we could not conduct air or steam test to really ensure that the welded portion is properly sealed. With that in mind, the fitters must properly weld the leaking section. They welded a few layers to ensure there’ll be no leaking at all.
While the welding job is in progress on the ground floor, another big vessel on the first floor was externally caught on fire. Smoke rushed out from underneath the insulation and we can see fire coming out of it as well. We swiftly grabbed the fire hose and spray water towards the fire.
It was the insulation wool that was actually burning. The big vessel has some hidden leak and when the plant breaks vacuum, oil came out of it. Combination of oil, high temperature and air triggered the fire as the flash point was reached. That was not the first time. It had happened several times during plant start up or stoppage. Luckily, we managed to put off the fire. However, we continued spraying water to cool down the hot insulation wool. We also poured few pails of low concentrated caustic to encapsulate all leaked oil (hydrocarbon molecules) in the insulation wool.
As soon as the situation on the first floor was under control, the welding job on the ground floor was also completed. Everything looked fine and the plant is ready to start. The vacuum system was slowly established and crude oil is pumped into the plant. After I was really satisfied with the overall situation, I left the plant, relieved that we have identified the prime pumping problem that haunted us all these while. It was already dark and I was very exhausted.
That was the problem # 2 that recently occurred in the plant. I shall continue with problem # 1 followed with problem # 3 in few days time. Oh yea, the photos are not actual events of what occurred in the plant.
From my previous post, I stated about having three problems in the plant while starting and stopping it. I'm going to share our experience on problem # 2 first. I'll post problem # 1 in a few days time. There's no particular reason for me to post about problem # 2 first instead of problem # 1. I just think problem # 2 is more interesting and I learned a lot from it.
Problem # 2 – Inconsistent pump flow
The pumps below a buffer tank could not deliver the required flow rate that they are supposed to. The flow rate was extremely slow and the discharge pressure was not consistent at all. The pressure went crazy up and down from 0.5 to 5 bars. We tried to adjust and play around with the pump in order to get the desired flow rate.
Slow flow rate means lower throughput, hence lower production. In actual, if we keep on running with the low flow rate, production will be 50% less. We could not afford that to prolong. We have heavy shipment ahead and we need to immediately rectify the pump problem.
There were all together 3 pumps in a row of similar motor kW and pumping capability. Initially we thought all three pumps were having some problem (or the same problem). We asked the maintenance fitters to check, service and replace the mechanical seals. We checked the pump pressure and found it was OK because the discharge line pressure can go up to 4 – 6 bar. There’s no way the pump is having a problem.
Then we thought it was Net Positive Suction Head (NPSH) problem. We increase the level of oil inside the buffer tank so that the NPSH will increase. That didn’t work either. The flow rate was still low and the discharge pressures were inconsistent.
By this time, we suspected the pumps were experiencing serious air-lock. Air-lock is a situation where the pump could not pump efficiently and effectively due to some disturbance from air turbulence inside the pump suction line. The pump discharge line pressure inconsistency might be due to the air-lock problem. The question now is where the air is coming from? We decided to thoroughly check the pump suction line to search for any hole/leak (which air may easily enter because the tank is operating under vacuum). We removed the insulations covering the suction line, checking and inspected it, but still we could not see or detect any leak (because the tank and pipe was under vacuum, which means oil would not pour/come out from the leak due to vacuum holding it). Time was running fast but we have not yet settled the problem. We began feeling the pressure coming from our superior/management.
After almost one day running low, we made a more drastic and radical move. We hold the plant and braked vacuum – stopped production. We waited for a while. At first, we noticed nothing. The pump suction pipeline looked fine. After 15 minutes, we were caught by surprised on what we saw! Droplets of oil came out from the tank insulation. At first, it was little, but then there were more and more oil pouring out. This confirmed that there is a leak somewhere underneath the tank insulation. We cautiously removed a small portion of insulation covering the tank where the oil came out (because the oil and the surface was extremely hot (260oC)).
After successfully removing the insulation, we saw oil pouring out from the welding joint between the tank and the pipeline. We looked at each other, wandering how we are going to resolve the already identified problem. We cannot simply weld the leaking point because there traces of vacuum was still inside the tank and system. If the maintenance fitter welds the leak point, we fear spark may enter the tank (and system) and trigger fire inside the tank, pipeline and other vessels. At the same time, it is impossible to weld the leak point because oil was coming out from the tank. Should we drain the balance oil in the buffer tank? If yes, that would cost a lot of time, estimated half a day. Just imagine the downtime we already faced and add up another half a day for repair work and starting up the plant again. We have to think of a better and faster way to weld the leaking point.
Finally we came out with a very risky idea but can solve the problem faster. We have to maintain a slight vacuum inside the buffer tank just to hold the oil from pouring out from the leaking hold.
Everybody enjoys having a happy hour meal at the most famous franchise fast food restaurant - "Mcdonalds" and that includes me. In fact, I just had a nice dinner with my family 2 days ago in Mcdonalds Jaya Jusco Johor Bahru. As I googled about processing plant, I found this very interesting short video on how the meat for their famous burgers are processed. It is amazing to learn about their hourly quality control (QC) to ensure that the meat is tasty and juicy before packing it. The cleanliness factor is also strictly taken into consideration. After neatly, safely and cleanly wrapping the boxes (which contains the meat), they're distributed throughout the States.
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."
My respond/answer;
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...
I subscribe to a lot of chemical engineering ezine/newsletter and other stuff like equipment/machine processing (to enhance my knowledge - Nowadays knowledge is money!!!). One of them is Genemco (a site dedicated providing information and selling food processing equipment).
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You can subscribe to the newsletter from the Genemco site. Check it out.
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!
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boiler in make up water or as air is sucked into the system. Dissolved oxygen is extremely corrosive to your tubes and localized pits will form, ultimately resulting in premature tube failure. Maintain a 20 to 40 ppm residual of sulfite in your boiler water.
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