What can Elevators and Escalators tell us about "Variance"
Published in People
Published in People
Published in On the Job
If we look at the DNA of the people from EPC world, we will find there are two types. There are people who love drawings, schedules and networks and there are others who love their hard hats and safety shoes.
After completion of all the tasks involved in the overhaul, the pump cartridge was finally assembled and inserted in its barrel casing, centered and aligned. The design of this pump was so precise that the acceptable interference, clearance, centering and alignment tolerances were in the range of one thousandth of an inch. The width of human hair falls in this range.
I have some interesting observations during many project experience. One of these is that important mile stone activates at project sites eventually spill over to late evenings when the energy levels are at the lowest. On one such late evening, before coupling this pump, the lube oil system was started and was kept running for some time to see everything was fine. One of our technicians was instructed to start manual rotation of the pump. The pump rotor was freely rotating without much of problem. But the fitment of the rotor must have made the manual hand rotation of the pump rotor a little hard for the technician who became tired and requested another technician to take over the task. During the transition, the rotor must have briefly come to a standstill before the next technician took over. Panic took over the entire group when the second technician could not restart the rotation. I had a shock of my life, when he said, “Sir - ye pump nahi ghoom raha hai” (“Sir - this pump wont rotate”). We tried for some time with all our energy, but did not apply more force trying to rotate the pump. We thought we might damage something in the pump if we do that.
We all sat down trying to think – what next? But we could not imagine anything new. We were physically tired but mentally getting prepared to restart working to dismantle the pump again. However, wisdom prevailed on us, and we called up our Maintenance Head Mr. P.R.Wadia and told him about the status of the pump and how it got jammed during manual operation. I looked at my watch before we called his number. It was 11.30 PM. Mr.Wadia promptly took the call and said very coolly, “Couple the pump and give it a kick start”. We all looked at each other. In any case the pump has to be dismantled if there was any fitment or other problems. So why not give it a kick and see if it frees up? We did not do any risk benefit analysis at that point of time. We were just waiting to follow instruction only - like a bunch of robots. So, we coupled the pump to the motor and then took name of God and gave a start command to the motor. Without any observable problems, the pump started and was operating smoothly. Relived and relaxed, we went home and had a peaceful night of sleep. This was 1998.
Fast forward 17 years to 2015. In my assignment as Project Head of Jhabua Power Ltd., one of my engineers working in Boiler called me up one evening. He said, they were supposed to take trial run of ID Fan. Since, this trial run was being conducted after a long gap several months after erection of fan, it was agreed with EPC contractor to manually rotate the fan to see if the fan is free and then start it. Even after lot of effort the fan did not move manually. I knew it was my turn to return the favor and learning. I told him to go ahead and give it a kick start. Although I was confident that there was no problem with the fan, I was eagerly waiting for a return call from Bhupinder. And then Bhupinder called me back and told me that the fan was operating smoothly.
I looked up to the sky and thanked Mr. Wadia.
That is where he lives now.
What a “first boss” he was.
Published in On the Job
Here are four relays and an ice cube.
The four relays shown above are called ice cube relays because they look like ice cubes. But what does a relay actually “relay” and why is it so called?
These are narration of actual on the job experiences. Someday, someone, at some project, did something that was memorable to you. That someone could be you or your friend or your boss or your supervisor or any one on the job at the site or office. Was it a call beyond the duty that was taken? Passion, dedication, pride to do something better are the central theme.
Published in On the Job
If we look at the DNA of the people from EPC world, we will find there are two types. There are people who love drawings, schedules and networks and there are others who love their hard hats and safety shoes.
After completion of all the tasks involved in the overhaul, the pump cartridge was finally assembled and inserted in its barrel casing, centered and aligned. The design of this pump was so precise that the acceptable interference, clearance, centering and alignment tolerances were in the range of one thousandth of an inch. The width of human hair falls in this range.
I have some interesting observations during many project experience. One of these is that important mile stone activates at project sites eventually spill over to late evenings when the energy levels are at the lowest. On one such late evening, before coupling this pump, the lube oil system was started and was kept running for some time to see everything was fine. One of our technicians was instructed to start manual rotation of the pump. The pump rotor was freely rotating without much of problem. But the fitment of the rotor must have made the manual hand rotation of the pump rotor a little hard for the technician who became tired and requested another technician to take over the task. During the transition, the rotor must have briefly come to a standstill before the next technician took over. Panic took over the entire group when the second technician could not restart the rotation. I had a shock of my life, when he said, “Sir - ye pump nahi ghoom raha hai” (“Sir - this pump wont rotate”). We tried for some time with all our energy, but did not apply more force trying to rotate the pump. We thought we might damage something in the pump if we do that.
We all sat down trying to think – what next? But we could not imagine anything new. We were physically tired but mentally getting prepared to restart working to dismantle the pump again. However, wisdom prevailed on us, and we called up our Maintenance Head Mr. P.R.Wadia and told him about the status of the pump and how it got jammed during manual operation. I looked at my watch before we called his number. It was 11.30 PM. Mr.Wadia promptly took the call and said very coolly, “Couple the pump and give it a kick start”. We all looked at each other. In any case the pump has to be dismantled if there was any fitment or other problems. So why not give it a kick and see if it frees up? We did not do any risk benefit analysis at that point of time. We were just waiting to follow instruction only - like a bunch of robots. So, we coupled the pump to the motor and then took name of God and gave a start command to the motor. Without any observable problems, the pump started and was operating smoothly. Relived and relaxed, we went home and had a peaceful night of sleep. This was 1998.
Fast forward 17 years to 2015. In my assignment as Project Head of Jhabua Power Ltd., one of my engineers working in Boiler called me up one evening. He said, they were supposed to take trial run of ID Fan. Since, this trial run was being conducted after a long gap several months after erection of fan, it was agreed with EPC contractor to manually rotate the fan to see if the fan is free and then start it. Even after lot of effort the fan did not move manually. I knew it was my turn to return the favor and learning. I told him to go ahead and give it a kick start. Although I was confident that there was no problem with the fan, I was eagerly waiting for a return call from Bhupinder. And then Bhupinder called me back and told me that the fan was operating smoothly.
I looked up to the sky and thanked Mr. Wadia.
That is where he lives now.
What a “first boss” he was.
Published in On the Job
Here are four relays and an ice cube.
The four relays shown above are called ice cube relays because they look like ice cubes. But what does a relay actually “relay” and why is it so called?
Published in On the Job
Engineering Design usually has a very definitive approach and one has to work through a given input conditions for an intended output utilising calculated/predicted performance/behaviour of individual equipment and systems. But commissioning is always a challenging and thrilling task as we try to match the behaviour of actual equipment and systems at the site with predicted design values under different environmental conditions as well as uncertainties in the process of equipment manufacture.
This is purely about people; about everyday heroes. This could be technical and at the same time human. Description of Managing a difficult situation or feeling that is common under stressful situations at project sites. Wisdom from Technicians, mechanics, electricians, welders can make excellent narratives. Funny misunderstandings, cultural musings with foreigners, languages differences, etc.
Published in People
Published in People
More often we hear engineering and construction feats that technical staff at project sites achieve under extreme and challenging conditions. Acquiring land required for the project, and managing the expectations and aspirations of local people and land oustees is a challenge that is faced by and left to HR department (erstwhile P&A dept. of the hey days). Heroic stories of personal risk-taking beyond the call of duty from the early phases of project life are neither popular nor shared widely. Here is a story that I was involved first hand as a young executive in NTPC, which left a lasting impression on me.
Published in People
When we have hands on real life experience about how certain things work, we can go to great lengths to demonstrate what we know so that others can learn and take correct decisions. But it needs fearless fortitude to uphold what you believe in - when it means putting your career and sometimes your own life at risk.
These are your one liners, that life has given you. You remember them because someone explained you something complex or even simple very well and them summed up it for you so well that it is still there in your memory. If related to technology it will be wonderful. But that is not necessary. The background and the situation are the key ingredients. Simple situations seen from a different angle by wise people.
Published in Pearls of Wisdom
Today is Teachers day. Here are some memories of a great teacher.
Some of the most wonderful gifts that God sends our way are the people we come across in our working career. And if such a person happened to be your boss, the experience is memorable and life changing. When I met him, it was as if I stumbled upon the best teacher life could offer after twenty-one years of working life.
Published in Pearls of Wisdom
The human mind, it is said is a bundle of ideas. Everyday ideas, big and small come and hit us. We put them through different filters. What we do with them decides what we become in life.
We consider some as too big for us.
We consider some as too small us.
Some we think are not workable.
Some we do not attempt because others have failed at them.
We think some will only work for us if ......
We think some will not work for us because ........ So on and so fourth.
Published in Pearls of Wisdom
In NTPC, a large number of measures were introduced right from the inception to ensure the welfare and growth of not only employees but also their family members. Such efforts included energizing Ladies Welfare Organizations, sports competitions for children of employees, coaching facilities for competitive exams for children besides making available good educational facilities at projects. We innovated substantially, with involvement of employees, their families and the HR executives in the field and based on the feedback and appraisals took a lot of initiatives to update the services that were being provided.
Many times lessons learnt from small things and simple events are profound and act as a beacon for the rest of our life. Many times it may be about how something must not be done as against smartness of ready wit that can make the most drama in life. You learnt the trick for many years and one day a small incidence turned your opinion upside down. Why? That will make a wonderful narrative. Such stories are contagious. Readers will be compelled and encouraged to respond, comment and may even write.
Published in Lessons for Life
This story is from my experience while I was working at the Auriya Gas Power Project (AuGPP) of NTPC. I remember this story vividly; like it happened yesterday.
When this incident took place I was posted in the HR (erstwhile known as P&A) department and was looking after Administration. During those early formative years, the project was my learning ground. Being at the initial stage i.e construction, the project was a hub of activities. I was simultaneously involved in many complex and hectic activities, dealing with administration, security related issues, liaising with State Government Authorities and interaction with local people, etc.
Published in Lessons for Life
The weekend drew near. 6 pm to be precise, on a fine Friday evening, with a light gentle rain splattering on my window at the AT&T Office in Tech Mahindra. Possibly about 20 degrees centigrade if I guessed right. Perfectly fine , I thought to myself . “Ideal weather to stop work “, my inner voice told me. “Absolutely” ! , I told my inner voice, heartily agreeing to these brilliant suggestions.
For experts, this one is going to be the most difficult. Because in the long years that we become experts, we almost forgot the perspective of simplicity. We forgot the questions that were in our mind when you were young, novice, like a newbie. Somewhere, someone, something, cleared those dreadful questions that normal people don't ask experts. If you remember those questions and who, how, what, when, which book, which movie helped in making you an expert, write about it here. Be very worry some of the language because the terms that you use may not mean anything to domain outsiders.
Published in Technology
What surrounds what in “Surround Sound”, and why is it so called?
Why a typical surround sound system is called a “5.1 system” ?
A little bit of history of “sound recording and reproduction” will help to build a context to answer these questions meaningfully. Here it is. The method of recording sound and reproduction evolved between 1920 to 1945. At around 1950, two things were achieved.
During those days listening to quality musical performances was only possible live – you had to be there at the performance. For a long time AM Radio stations reached out to millions by replaying recorded sound of such performances. Radios of those days, had one small speaker. Since all sound (instruments and the voice of the vocalist) come from this speaker only, this mode of listening was called “monaural” – meaning “one sound”.
Published in Technology
There are times when life puts a wall in front of us, when no medicines work, when all available tools are of no use, when all that we know is irrelevant, when none of our experience comes in handy. At moments like these, all that goes on in our mind translates in to one simple question - Now what? This simple but profound question stirs our emotions, baffles our intelligence, makes us helpless, forces us to reboot and relearn and leaves us with memories for a life time. Times when we came to face this question are the turning points in our lives. They shape our lives, build our characters and make us who we are.
But those are also the moments when innovation triggers in some corner of the human brain. New concepts, new instruments, and new methods evolve. The initial spark of imagination in the mind of one passionate and fearless individual appears absurd at first but slowly gets refined and gains acceptance. Over the years it spreads to impact everything - companies, industries, communities, societies and even countries. Thus the old appears irrelevant and often incorrect and gives way to new.
The life cycle of large infrastructure projects is no different. They also go through this inevitable process of evolution. When major components of large projects cannot be interfaced correctly to work properly because wrong components have been delivered at project site, this question comes back to hunt everyone - Now what?
Whenever items delivered to a project are incompatible, site Field and Commissioning engineers take on the challenge. If possible and acceptable, they try to modify the interface in such way that the item can be used without extensive rework and modification to avoid costly reorder. But once in a while the sheer physical size of a component is so large that it is just not possible to carry out any physical modification whatsoever in any manner because suitable interface changes are just not possible. This is exactly what happened at one NTPC power station, where during the commissioning of the generator transformer it was found out that the generator bus ducts were of wrong design. This story describes what the impacts were and what was done at site to resolve the problem to go ahead with the project.
Large utility generators like those of 500 MW capacity, have three bus ducts, one for each phase that connect the generator to the generator transformer. These are aluminum tubes of about a meter and half in diameter, more than a few centimeters thick with an aluminum conductor centrally supported by insulators. These tubes come in pre-fabricated transportable spools and are welded together at site. When the spools are welded together as designed, the bus duct takes the shape it is intended to and connects the generator, generator transformer and the unit auxiliary transformers in a pre designed manner.
The main GT at the project comprised of three single-phase transformer units (connected externally through the generator bus duct) to act as a three phase transformer. On the generator side, the low voltage windings of the three single-phase units are connected as a "delta". For forming a delta on the LV winding, each bus duct coming out of the generator is split into two smaller ducts. R&Y go to the first transformer, Y&B go to the second and B&R to the third transformer. On the grid side, the high voltage windings of the three single-phase units connect as "star". This particular connection creates a phase angle difference of 30 degrees between the HV and LV of the GT. Keeping this phase shift in view, the unit auxiliary transformers are so designed that this phase shift is compensated.
Published in Technology
In our first story, we have seen the evolution of pumps. In the second, we have learnt how centrifugal pump infuses energy into the fluid through the impeller. Besides, there are positive displacement pumps, which also impart energy into the fluid through physical movement of the liquid mass. So how do we decide which type of pump is best suited for a hydraulic system design? Let’s take a glimpse at the classification of pumps and understand the basic working philosophy of each type.
Broad classification of pumps based on working principle can be seen in Figure 1 below –
Figure 1 - Broad Classification of Pumps
A. Rotodynamic
Leading by the term, rotodynamic pumps work on the philosophy of continuously adding kinetic energy to the working fluid through a rotating device i.e., the impeller. The category has been further divided into three (3) sub-categories based on impeller construction vis-à-vis the direction of fluid flow exiting the impeller. Figure 2 below provides typical sectional view and characteristics of these categories of impellers.
Figure 2 – Typical impeller construction & characteristics in Rotodynamic Pumps
• The Radial Vane or Centrifugal type
Impellers under this category will force the fluid to exit the impeller in the radial direction by the influence of centrifugal force while the fluid enters the impeller eye in the axial direction. The discharge fluid gets collected at the pump volute casing and guided to the discharge. Please refer to Figure 3a. Technically, this type of pumps has low Specific Speed and is useful for developing high discharge head and can handle the relatively lower quantity of fluid. Impellers can be open / semi-open or shrouded type depending on the process fluid characteristics. Refer to typical sectional details of the pumps in Figure 3b, 3c & 3d below for clarity.
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Fig 3a – Working Principle of a centrifugal pump
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Fig 3b – Cut away view of a centrifugal pump
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Fig 3c - Sectional view of a double suction pump |
Fig 3d - Typical view of multistage centrifugal pump |
• Mixed Flow type
Impellers under this category and Francis type force the fluid to exit the impeller in an angular direction as can be seen in Figure 4a. Pumps with mixed flow type impellers have medium Specific Speed as can be seen in Figure 2 and is useful for developing medium discharge head. It can handle comparatively higher flow than a centrifugal unit. Typical view of open and closed type mixed flow impellers and sectional view of single stage mixed flow pumps are shown in Figures 4b & 4c below.
Figure 4a – Typical Mixed Flow Pump working principle
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Figure 4b – Typical Mixed Flow Impeller construction
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Figure 4c – Typical Mixed Flow pump construction
• Axial Flow type
Impellers under this category are sometimes denoted as turbine type and are designed to push the fluid in the axial direction as can be seen in Figure 5a. Pumps with axial flow type impellers can handle large fluid volume as compared to other two categories and develop low discharge head. The impeller is characterized by the highest band of specific speed as can be seen in Figure 2. Typical impeller construction and sectional view of axial flow pumps are indicated in Figure 5b.
Figure 5a – Typical Axial Flow Impeller & pump construction
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Figure 5b – Typical view of Axial Flow Impeller & pump cross-section
Rotodynamic impellers have been further developed through researches by the pioneers in the pump industry to satisfy various process needs, handle dirty water & slurry as well as for pumping fluids other than water. For handling slurry or waste water containing solids, semi-open or open type non-clogging impellers are used. Typical view of these impellers can be seen in Figure 6.
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Figure 6 – Typical view of closed, semi-open and open type Impellers
B. Positive Displacement Type
As the name implies, this category of pumps physically pushes the fluid from suction to discharge. Positive Displacement Pump has an expanding cavity at the suction side and a decreasing cavity on the discharge side. Liquid flows into the pumps due to fall in pressure as the cavity on the suction side expands and the flows out of the discharge as the cavity collapses. Volume flow through the pump is constant in each cycle of operation.
Positive displacement pumps are classified into two main categories based on working principle.
• Rotary
A rotary pump traps fluid between a rotating element and the closed casing at the suction side and transports the fluid along with the rotary element until it gets discharged at the outlet due to space constraint. It is normally a fixed volume machine and maintains a constant & uniform flow across all discharge pressures. Single or multiple rotor elements can be used in a rotary pump design, as can be seen in the following section. Major distinctive type rotary pump designs are -
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Figure 7 – Typical working view of Gear Pump and construction
Pumping activity is achieved by teeth of two rotating gears meshing each other fitted in an enclosed casing. Liquid trapped between the casing and the gear slots at the suction is carried by the teeth and discharges at the pump outlet. The meshing of teeth of two gears at center prohibits liquid backflow from the suction to discharge side. Both the gears are driven by a common driver.
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Figure 8 – Typical view of Twin Lobe pump & cross-section
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Figure 9a – Typical view of sliding vane pump & cross-section
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Figure 9b – Typical view of Flexible vane pump
In the case of flexible vane design, vanes collapse to reduce the trapped volume as they approach closer to casing near discharge point to force the liquid to come out of the pump. Please see Figure 9b.
Figure 10a – Typical Archimedean single screw pump
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Figure 10b – Typical view of Twin Screw Pump & cross-section
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Figure 11 – Typical cross-sectional view of a Progressive Cavity Pump
• Reciprocating
As the name implies, to and fro motion of a moving element is used for pumping the fluid. In a reciprocating pump, the liquid is drawn into the cylinder through the suction valve as the piston or plunger moves away from suction point creating a vacuum in the cylinder. Reaching the other end, piston reverses its motion due to crankshaft arrangement and the trapped liquid is discharged through the outlet valve under positive pressure due to a reduction in trapped volume while the suction valve remains closed. See Figure 12. The discharge from a reciprocating pump is therefore pulsating and the discharge volume is fairly constant for a specific pump size and drive speed irrespective of the discharge pressure. The operation of the pump is also independent of the rotational direction of the drive when compared to a rotary or rotodynamic unit.
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Figure 12 – Working Principle of a Reciprocating Piston Type Pump
Reciprocating Type Pumps have been further categorized based on their reciprocating mechanism as can be seen below -
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Figure 13a – Working Principle of a Reciprocating Piston Type Pump
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Single Acting | Double Acting |
Figure 13b – Working Principle of single and double acting Reciprocating Piston Type Pump
The piston or plunger type pumps can be single or double acting type as can be seen in Figure 13b. In a double acting system, two sets of suction and discharge valves are used, one set at each end of the cylinder so that while piston moves from left to right, the left side of the cylinder is in suction mode and right side goes in discharge mode. The situation reverses as the piston moves from right to left.
Figure 14a – Working Principle of a Diaphragm Pump
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Figure 14b – Working of a Diaphragm Pump using hydraulic device
Metering Pumps or the Controlled Volume Pumps are basically a modified version of the diaphragm pump, wherein the stroke or the frequency of the plunger movement is regulated using a stroke control mechanism or a variable frequency drive. Figure 15a below shows how a micrometer adjuster is used to regulate the stroke length of the plunger and thereby discharge volume. Figure 15b shows a cut-away view of the metering pump.
Figure 15a – Working of a Metering Pump using hydraulic
Figure 15b – Cut away view of a Metering Pump
I believe it has been an enjoying session for a beginner to understand pump types and their working principle. Further details may be studied in various literature published on the subject.
In our next story, we will talk about performance characteristics of pumps and their behavior in a hydraulic system. Stay Tuned !
We humans are emotional beings. People, things, places, associations, sometimes leave a lasting impression in our hearts and mind. This section is devoted to those.
Published in Nostalgia
Sometimes in life, you hear from someone a story from his childhood without him knowing the kind of role you played in the making of the story.
During a recent visit to a site, almost 20 years after the glorious project days, while passing around the beautiful fountain in front of the township gate of NTPC's Talcher Kaniha Project in Odisha, the driver of the car narrated his childhood memory of an incident. The incident has become a story of the past. People involved in that fateful incident are now faithful old employees of the company. Although many people might have forgotten the story, there are others like our driver, whose words triggered open a floodgate of vivid memories. We smiled at each other while showing our Identity (ID) cards to the security guards for entry to the township on our way to the Guest House. I closed my eyes and the old incident replayed like a movie in front of me.
Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Aenean lacinia bibendum nulla sed consectetur.
Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Aenean lacinia bibendum nulla sed consectetur.