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My PLC (Programmable Logic Controller) Experience

At work there are still a lot of things to be done. The latest, hottest and interesting job in my list is the PLC (programmable logic controller) upgrading in my plant and control room. For me, this is a very enriching project and an excellent learning experience for me. All these while, I've been monitoring the temperature, flow rate, pressure, utilities, processes, costing, equipments, instrumentations, reports etc., but now I'm going to get myself a little bit familiar with the plant control system. Previously, at university, I don't really fancy process control; and advance control subjects, but now, I'm beginning to be develop some interest in them. However, if I'm not mistaken, the subjects don't really touched a lot of PLC stuffs.

OK, back to the present moment. Every process plant must have their own PLC to run the process or production plant. If not, the plant operators have to switch the pump, flow meter or other instruments manually and that's impossible at this era. It will be very difficult for them to control and monitor a running plant.

Lets see some definitions of PLC. According to Wikipedia: "A PLC is a digital computer used for automation of industrial processes, such as control of machinery on factory assembly lines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result."

A non-technical term to describe a PLC: A PLC is the type of computer that controls machines. The PLC is used to control and troubleshoot machine. The PLC is the brain of the machine. Without it, the machine is dead.

For the past few days, I've been studying the input/output (I/O) arrangements at the control panel. These connect the PLC to sensors and actuators. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. On the actuator side, PLCs operate electric motors, pneumatic or hydraulic cylinders, magnetic relays or solenoids, or analog outputs. The input/output arrangements have external I/O modules attached to a computer network that plugs into the PLC. The I/O points consists of digital input, digital output, analog input and analog output. I checked them and counted how many spare I/O points are available to be used for additional pressure transmitter, RTD, inverter and pump that we're going to install (which is part of some slice of plant upgrading projects).

Hmmm....I guessed, that's enough for some brief introduction on the PLC. I may continue about my PLC adventure in future.

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posted by zaki yamani @ 11:06 PM, , links to this post

From the Chemical Engineer's wife

My husband has been begging me for quite some time already to write a post here in his blog. It’s not that I don’t want to, but I personally think you guys out there prefers to here from him than from me. Out of his mountainous work load, he seems like the busiest men on earth. Despite of him trying his hardest to update, sometimes he can’t catch up. So here I am, writing my two cents worth…..

I am now in my fourth semester of my Chemical Engineering Phd in a local university (Malaysia). It is not the most joyous experience for me. Since I was little, I hate studying. I have to do this one just because my faculty wouldn’t let anybody off without a PhD. What a bugger. However, it is not as heavy as doing my first degree back in England as I don’t have to attend classes or any exams..what a relief. The hardest part is getting myself organized and focused.

My supervisors are both very helpful and they do not force me to do anything. They just let me be independent. I don’t have to see them every week and they don’t even bother if I don’t see them for months…hahaha. There are goods and bads in that. The good part is that you don’t have to work like a horse in meeting their target and you don’t feel pressured. However, the danger is that you will be progressing very slowly. You will not be writing papers (journal, conferences), your experiments went on in a slow pace and you will be jeopardizing you PhD. Therefore, the key is discipline!! No matter what kind of supervisor you have, just discipline yourself and have your own set of targets. If your supervisor is the pushy type of person, just work with him/her and do everything he/she asked for. If your supervisor just let you be, arrange appointments to see them to discuss your targets/progress/plan. They wouldn’t say no, they just want you to work on your own pace. So if you think you are not a highly disciplined person, choose a supervisor that can make you work for it.

The relationship between student and supervisor is often difficult to orchestrate. Some supervisors treat their students as colleagues and friends, others prefer to maintain a formal teacher-pupil relationship. In any case, your PhD supervisor will be an important figure in your life for at least the next three years. Your PhD will inevitably affect the rest of your career, so take some time to consider not just what and where you'd like to research, but who you'd like to work with.

Here are some tips on How to Choose your PhD Supervisor.

1. If you’re doing your PhD in the department where you're doing your first degree or where you are currently lecturing, just ask these questions: Does he know your name? Can you face another three years of his jokes? If you're already calling him 'Uncle Keith' it may be time to move on.

2. If you’re doing your PhD in another institute:

- Approach someone whose work you know from the literature. It's important that there won't be a major clash of interests and personalities.

- Look around the department and assess your potential supervisor's standing. (if you could go)

- Talk to his other students (emails are also ok). Are they relaxed, confident and busy or do they have a glazed expression and a compulsion to look over their shoulders? Have they published single author papers? First author papers? At all?

- Communicate with him through emails. If he always answered your emails between lecture tour of Japan and a conference in Brazil, will you ever see him?

Hopefully this would be useful for those planning to do their PhD. Good Luck…

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posted by zura @ 11:02 AM, , links to this post

3 Blogs You Need to Check Out

Since I began this blog in August 2006, I did not notice other blogs related or dedicated to chemical and process engineering. That time, I started the blog with the name "Chemical Engineering World". After slightly more than one year, I'm glad there are more blogs related to chemical and process engineering. It's a good sign for the sharing of chemical and process engineering knowledge and experiences. A lot of students, young engineers and practicing engineers can benefit from these blogs.

Here, I would like to share 3 blogs that discusses about chemical and process engineering which are Chemical and Process Technology, Chemical and Process Engineering and Chemical Professionals.

The first blog is Chemical and Process Technology which is owned by Joe Wong, a practicing engineer in the Engineering, Procurement and Construction (EPC) industry in Kuala Lumpur, Malaysia. His blog is packed with useful facts and information related to the chemical engineering industry. If you want to learn more, check out this blog which is saturated with great pure engineering and technical stuffs. To make sure I don't miss any the post, I subscribe to this blog content.

The second blog Chemical and Process Engineering is owned and maintained by a final year dynamic and motivated chemical and process engineering student from Sri Lanka, Thushara. The blog is lighter in chemical engineering content and is an easy reading. Sometimes, he chip in some other useful informations outside engineering. I like reading his blog very much. I think I'm his second subscriber.

The third blog is Chemical Professionals which is owned by a very experience process technologist from India. He has more than 13 years of experiences of energy conservation, technology improvements, process scheme development, technology transfer and much more. I just discovered this blog few weeks ago, and since then I regularly visited this blog to catch up with other chemical engineering knowledge and informations.

If you are reading or notice other blogs related to chemical and process engineering, please inform or share it with us. It's good to share informations and experiences for the benefit of all chemical/process and related engineers. It's good to have a common community, a community of chemical/process engineers...

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posted by zaki yamani @ 6:51 PM, , links to this post

What I Get After My 5 Days Break

Yesterday, I began work after the 5 days break. It was a paradoxical emotion getting back to work while the festive season is still alive. It felt like the break was not enough. Would it be better if I can stretch my annual leaves to next Sunday. That would be a cool 9 days break for me. Well, I just have to face the fact that my annual leaves and public holidays are just 5 days. I have a number of responsibilities at work that requires me to get back to work early. One of the plant is stopped due to lack of raw material/crude oil and we are forced to take the opportunity to do some maintenance job.

Preparing a 5 days daily production reports after the break was not a speedy one as usual. It took me longer hours to prepare the report due to some changes in production planning. Having an annual management review meeting after lunch yesterday did not help me to reduced my job load. In fact, I received additional tasks and reports to be prepared within 48 hours. Up till now, I haven't completed the report yet. Well, I have to rush for it after this.

I also have to prepare for tomorrows maintenance coordination meeting. Wow..., there are really a lots of meeting here and there. With the plant stoppage and maintenance going on which have to monitored from time to time, I tried my best to manage and coordinate as good as I could. It's really a challenge for me to handle a lot of the projects, tasks and other jobs all at one time. Luckily, I'm still OK. We have good executives and supervisors to assists us executing the jobs. So far the plant operators and fitters are doing fine although manpower are still limited and lacking due to some of them are still on their annual leaves (remember, it's the festive season...).

I appreciate all of these as a good training experience for me. I hope other junior engineers/going to be engineers anywhere can be confident and strong enough to face any situations when they're really tested up to the maximum . They must be mentally tough and able to lead and keep track with the expectation from their superior. Anybody want to share their experiences...?

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posted by zaki yamani @ 11:08 PM, , links to this post

My 5 Days Break

I'm going to celebrate Hari Raya Eidulfitri Festive season a day after tomorrow. It's a big day for me and my family and the rest of the Muslims around the globe. We'll be traveling to my wife's hometown which is about 300+ km from our home. I'm taking a 2 days annual leaves + 3 days public holidays. That's a total of 5 days and I'll try my best to really enjoy this break. I don' want to be interrupted by phone calls from the plant/my work place. I don't want to think about the plant. I just want to relax my mind for a while. I want some peace...

My plant will still be running this coming festive season. Luckily my senior colleague is there to take care of this very important plant. He have been guiding, mentoring and supporting me all this while and I really appreciate it. I'm learning a lot from him (and his precious experiences).

On normal days, as a process engineer, I have to take care of the plant 24/7. That means to be alert and know what is going on in the plant at all time. I'm answerable on everything and anything that is happening to the plant. It's a really big and huge fast moving plant that we cannot afford any error. If not, the downtime will be very costly and I'll have difficult time explaining it to my superiors.

To be frank, I have to say that at all time, my mind will be focusing on the plant. While driving, going to sleep, taking bath, having dinner, outing with family, somehow, I'll think about what's happening in the plant. Is the plant OK? What if the oil quality is off spec? Is the flow rate maintained? Is the oil product sent to the correct tank? Is the vacuum pump OK? Are we getting the required process temperature? Is the steam supply enough? All these linger in my mind. Sometimes, in order to sleep peacefully, I'll call the plant and ensure everything is silky smooth before resting and going to sleep.

On a daily basis, my supervisors will call me (and my senior colleague) every early morning at 5.30 AM and report to us about the plant progress. Therefore, when we arrive at work, we are well aware of the plant overnight situation and performance. If there are problems, the shift supervisor or shift leader will call us even though it is 2.45 AM or 4.13 AM in the morning (and we are in deep sleep with sweet dreams).

Well, now that I have the 5 days break - that means my mind is also free. I'll just relax and give my mind some break which it definitely deserve.

Ops....don't forget to check out the new Chemical-Engineering-Forum.com.

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posted by zaki yamani @ 10:38 PM, , links to this post

Disappointing New Plate Heat Exchanger Is Now OK...

This post is the continuation of the "Disappointing New Plate Heat Exchanger” post.

After installing and using the new plate heat exchanger (PHE), we could not get the flow rate and temperature. This was really a problem because we were expecting the new PHE to perform excellently.

The PHE seems to be leaking although we have tightened it from 540mm to 529mm. The minimum length we can go according to the design is 506mm. But that is applicable after running the PHE after certain duration of time, not tightening it while it’s still new.

I called the PHE supplier and asked what’s wrong with the PHE? What should we do? Should we tightened it some more? The leaking is only at the end plate. Should we dismantle and check the end plate? Maybe the gasket is not evenly glued on the end plate? Maybe the gasket is damage or distorted!

The technical engineer came the following day and we performed an air test to show him the leaking points. He noticed the leaking point and agreed to dismantle the PHE to check what it wrong.

After dismantling the PHE, we found out that one plate is not arranged correctly. That was very surprising and it was not supposed to happen for a branded and reliable heat exchanger from Germany. Soon we found out that the heat exchanger was actually fixed locally by the supplier’s principal and not by the manufacturer in Germany.

The technical manager then guided our maintenance fitters to fix back the plate heat exchanger. Carefully they checked the plate’s arrangement. Diversion plates, flow pates and end plates must be in correct order. We don’t want to repeat the same mistake. If not, we are just going to waste our time and energy.

After completed fixing the PHE, we conducted air test and hold the pressure at 2 bars. We used soap liquid to check for any possible leakages. The pressure maintained for nearly one hour and that was good sign that the plate heat exchanger is not leaking.

We then gradually used the PHE and finally we get the desired temperature and flow rate. I’m so happy and glad that the new PHE is working perfectly as we plan. Now, we are focusing on other improvement and maintenance job such as cleaning in place (CIP), insulation, spare pipeline, and others. We’re taking it one by one.

Moral of the story:

1. Don’t expect a product or service to be perfect. Hope it to be perfect! If not, trouble shoot as soon as possible.

2. Be extra careful while arranging and dealing with plate heat exchanger. Once your arrangement is wrong, the entire effort is a waste.

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posted by zaki yamani @ 12:39 AM, , links to this post

Some Updates + Picture of the Day

I apologize for not updating according to the frequency I'm supposed to. I was really busy at work, packed with family events and gathering, and attached with some religious commitment in this fasting month (for Muslim).

I also owe you guys the updates on the "Disappointing New Plate Heat Exchanger" story that I posted 2 weeks ago. I'm working on the post and I shall get you guys updated by this week.

At work, the job seems never ends. Today, an internal audit took place for my plant. In brief, I can say the audit went fine and no non-conformance (NC) was charged. We only have one observation which was not really a big deal. However, from the audit, I learned a lot of new things. For me, all audit process is unique and will always give me new experiences.

As far as the plant is concerned, last week everything was silky smooth. We met daily production target capacity and produced on-spec quality. However, by the end of the week, something went wrong which made the flow rate slower. We have predicted this and we are working on some solution for it. Can you guess what made the flow rate slower? Well, have fun guessing...

The photo below is not really related to the story above or to my current job scope. I found this photo while browsing the net and I thought it's worth sharing with you guys. To tell you the truth, I'm not sure which platform and where the location is. It must be a really terrifying and scary moment if we are on that platform. Anybody have a clue where, when and which platform is this?

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posted by zaki yamani @ 11:25 PM, , links to this post

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!

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