Tip #10 For Better Chemical Engineering: Pumps

Pumps play a very important roll in any engineer and especially for chemical engineers. Knowing how to operate and maintain a pump as well as read a pump curve play a key roll in running a plant or any process. There are 2 main types of pumps centrifugal (Kinetic), and positive displacement pump.

There are two main categories of pumps - kinetic and positive displacement. Almost all pumps fall into one of these two categories. The main difference between kinetic and positive displacement pumps lies in the method of fluid transfer. A kinetic pump imparts velocity energy to the fluid, which is converted to pressure energy upon exiting the pump casing. A positive displacement pump moves a fixed volume of fluid within the pump casing by applying a force to moveable boundaries containing the fluid volume.

Kinetic pumps can be further divided into two categories of pumps – centrifugal and special effect. Special effect pumps include jet pumps, reversible centrifugal, gas lift, electromagnetic and hydraulic ram. Special effect pumps are not commonly used relative to centrifugal pumps, so they will not be covered in this course.

Positive displacement pumps are also divided into two major pump categories – reciprocating and rotary. Reciprocating pumps transfer a volume of fluid by a crankshaft, eccentric cam or an alternating fluid pressure acting on a piston, plunger or a diaphragm in a reciprocating motion. Rotary pumps operate by transferring a volume of fluid in cavities located between rotating and stationary components inside the pump casing. The relative features of reciprocating and rotary pumps, as well as centrifugal pumps, will be covered in this course.

Capacity

The wide variety of centrifugal pumps manufactured offer a relatively large range of available capacities. Radial-flow and mixed flow pumps are used for low to medium capacity applications. For high capacity applications, axial-flow pumps are capable of delivering flow rates in excess of 100,000 gpm. Centrifugal pumps are not stable at low flow rates, although there are special low-flow centrifugal pumps available that can deliver flow rates less than 10 gpm. However, for extreme low-flow applications ( Reciprocating and rotary pumps are capable of capacities ranging from low to medium, with flow rates peaking at 10,000+ gpm. In theory, reciprocating pumps can be manufactured to deliver more capacity, but they become prohibitively large and expensive at high flow rates. Both reciprocating and rotary pumps are capable of delivering product at extremely low flow rates (fractions of a gpm), making them particularly suitable for many chemical injection applications.

Pressure

Centrifugal pumps and rotary pumps are best suited for low to medium pressure applications. Reciprocating pumps are usually specified for high pressure service, with capabilities exceeding 100,000 psi. Multi-stage centrifugal pumps can deliver at pressures of 6,000+ psi and may be the most economical choice at this pressure in high capacity applications. But, in most applications exceeding 1,000 psig, reciprocating pumps are more suitable, particularly in low to medium capacity service. Both reciprocating and rotary pumps will continually increase pressure when pumping against a closed discharge to the extent allowed by the driver’s horsepower. This can result in overpressure of the pump or piping components, so it is necessary to install a relief valve on the discharge of the pump capable of discharging the full capacity of the pump. A centrifugal pump’s pressure rise is limited to the shut-off pressure on the pump curve, which is always less than the design pressure of the pump (and the piping system if properly designed). A relief valve is only needed if no other measures are provided to detect low flow conditions and shut down the pump to prevent damage. The relief valve need only be sized to pass the minimum flow rate required to maintain stable flow and prevent excessive temperature rise.

Smooth or Pulsating Flow

Centrifugal pumps and most rotary pumps provide smooth, non-pulsating flow, while reciprocating pumps produce a pulsating flow. A pulsating flow may require special design considerations in the piping system. If the pump is not located near the suction source, then acceleration head can contribute to low NPSHA problems, which may require the installation of a suction stabilizer. A pulsation dampener may need to be installed in the discharge piping to reduce pressure surges resulting from the pulsating flow.

Variable or Constant Flow

Centrifugal pumps operate on a variable-flow, variable-head curve. As the discharge pressure decreases, the pump delivers a higher flow rate. At any given speed, reciprocating and rotary pumps operate at a constant flow rate regardless of the discharge pressure. There are specific applications that require either constant flow or variable flow. Metering pumps rely on a constant flow at varying pressures, which makes reciprocating pumps and rotary pumps suitable for this application. Piston pumps used for metering will often use an adjustable stroke length to allow the operator to vary the flow rate to meet the system requirements. Centrifugal pumps are favored where process conditions often require varying flow rates. For example, a level control valve must throttle the flow rate from a vessel to maintain a constant level in the vessel. A centrifugal pump is well suited to handle this process condition, whereas a positive displacement pump would either require a continuous recycle to suction or a variable speed driver to accommodate the variable flow.

Self-priming

Reciprocating and rotary pumps are self-priming. This is an important consideration where a prime cannot be maintained on the pump. Centrifugal pumps are not inherently self-priming, although some manufacturers do specially design self-priming units. External priming sources, such as an eductor or vacuum pump can also be employed.

Costs and Space Considerations

In an overlap region where the conditions are suitable to use a centrifugal, reciprocating or a rotary pump, the following rules generally apply: The reciprocating pump will generally have higher initial capital costs and will require more space relative to the centrifugal pump or the rotary pump. The reciprocating pump will generally have higher maintenance costs relative to the centrifugal pump or the rotary pump. The centrifugal pump will generally have higher annual power consumption costs relative to the reciprocating pump or the rotary pump because of lower efficiencies. Of course, there are many exceptions. These are just general guidelines. A pump that is selected for an application outside of its optimum operating parameters will almost certainly not follow these rules. For example, a rotary pump operating in a high pressure, abrasive-slurry service would probably have higher maintenance costs than a properly selected reciprocating pump. The close running clearances (particularly for high pressure service) required in the rotary pump would likely result in premature wear and frequent maintenance.

Fluid Handling

Centrifugal pumps are suitable for transferring a variety of fluids ranging from clean, clear non-abrasive fluids to abrasive-slurries. However, a centrifugal pump is not the best choice for pumping highly viscous fluids due to dramatic drops in efficiency at high viscosities. Centrifugal pumps are not normally specified for viscosities higher than about 4,000 SSU. Centrifugal pumps are also not well suited to pumping entrained air. Most centrifugal pumps can handle up to about 2% entrained gas and specially-designed pumps can handle up to about 10%.

Reciprocating pumps are well suited for transferring clear, non-abrasive fluids, as well as abrasive slurries. In fact, the relatively low velocities of moving parts within a reciprocating pump make it particularly resistant to erosion in abrasive-slurry applications, provided that the pump is properly designed for the service. Reciprocating pumps maintain high efficiencies when pumping highly viscous fluids and can easily handle 50% and higher volumes of entrained gas.

Rotary pumps can also handle high viscosity fluids and high volumes of entrained gas. In fact, many rotary pumps operate at their best efficiency at higher viscosities. However, rotary pumps are not well suited for pumping corrosive fluids or fluids with abrasive solids because of close clearances between rotating and static pump components.

Summary

The comparisons between different pump categories presented in this course are general. The information is intended to familiarize the student with some of the basic differences between centrifugal, reciprocating and rotary pumps. However, there are many different subcategories of pumps within these broad categories and there are many regions of overlap where multiple types of pumps in the same category and even in different categories would be suitable. Since every pump application is unique, each of the factors that influence the pump selection must be considered in detail.

14 Engineering Challenges The World Must Face

Engineers from around the world will hold discussions at The University of Texas at El Paso to address critical problems affecting the planet.
The National Academy of Engineering has called engineers to action by identifying the 14 “Grand Challenges” that need to be solved in order to improve quality of life and health, create a sustainable future and increase renewable energy.
UTEP will host “Building Partnerships and Pathways to Address Engineering Grand Challenges Conference” Feb. 8-10 at Union Building East, third floor, Tomás Rivera Conference Center. More than 80 research and government institutions from the United States, Europe, Latin America and Canada will participate.
The three-day conference will focus on finding innovative solutions to challenges that face our society.
The 14 “Grand Challenges” include:
Providing access to clean water
Preventing nuclear terror
Engineering better medicines
Advancing health informatics – Developing better health information systems to improve medical visits, counter pandemics and biological or chemical attacks.
Making solar energy economical
Developing carbon sequestration methods -- capturing and storing excess carbon dioxide to prevent global warming
Securing cyberspace
Reverse-engineering the brain – engineers are trying to create computers capable of emulating human intelligence.
Managing the nitrogen cycle – Engineers can help restore balance to the nitrogen cycle with better fertilization technologies and by capturing and recycling waste. Controlling the impact of agriculture on the global cycle of nitrogen is a growing challenge for sustainable development.
Providing energy from fusion – Fusion is the energy source for the sun. Human-engineered fusion has been demonstrated on a small scale. The challenge is to scale up the process to commercial proportions, in an efficient, economical, and environmentally benign way.
Restoring and improving urban infrastructure
Engineering the tools of scientific discovery
Enhancing virtual reality -- Virtual reality is an illusory environment, engineered to give users the impression of being somewhere they are not. It can be used for training, treatment, and communication.
Advancing personalized learning -- Instruction can be individualized based on learning styles, speeds, and interests to make learning more reliable.
The mission of the conference is to enhance student interest in engineering and science, and emphasize the critical role engineers play in solving issues impacting our planet.
The event is open to the public. To register, log on to engineering.utep.edu/grandchallenges Free registration ends Jan. 31. Registration will reopen on site Feb. 8 at a cost of $125 per person.
Keynote speakers will include:
- Victor Mendez, administrator of the Federal Highway Administration. A graduate of UTEP, Mendez received a Bachelor of Science degree in civil engineering in 1980. He earned a Master of Business Administration degree from Arizona State University. He previously served as Director of the Arizona Department of Transportation.
- Ray Orbach, director of the Energy Institute at The University of Texas at Austin. Orbach received his Bachelor of Science degree in physics from the California Institute of Technology in 1956. He received his Ph.D. in physics from the University of California, Berkeley. He was previously the U.S. Department of Energy's first undersecretary for science.
- Semahat S. Demir, director of the Biomedical Engineering Program at the National Science Foundation. Demir has led, developed and/or participated in 15 NSF and interagency funding programs. She is a fellow of the American Institute of Medical and Biomedical Engineers (AIMBE) and has received 55 professional awards and honors.
Researchers from different disciplines, industries and institutions of higher education will engage in discussions, share best practices for successfully establishing partnerships and identify what is needed to overcome obstacles to creating alliances among universities, industries and national laboratories.
“With a tremendous effort by the members of the organizing committee, we have been able to attract some of the brightest minds in the world in the areas of energy, urban infrastructure and biomedical technology to UTEP for this conference” said Richard Schoephoerster, dean for the College of Engineering.
The goal is to identify opportunities for synergetic research and strategic partnerships among research universities, Minority Serving Institutions (MSIs) and industry; to identify the actions needed to create a culture of collaboration that facilitates the formation of research partnerships; and to showcase the capabilities of faculty from MSIs.
“The recommendations coming as a result of the discussions over the three-day event will set the stage for research and development into these pressing societal needs, and UTEP will be positioned as a major participant in those efforts,” Schoephoerster said.
“This is entirely in line with our effort to become a Tier One research institution, and with our efforts to create opportunities for our students to contribute to a diverse engineering workforce,” he added.
The event is sponsored by the National Science Foundation with additional support from industry sponsors Freeport-McMoRan Copper & Gold, Lockheed Martin, Shell and Boeing.
Source: The University of Texas at El Paso
http://engineering.nitews.com/110e2

Tip #9 Of Better Chemical Engineering: Calculation

I must say in my short time of being an engineer is that you need to be able to do quick calculations. And, by that I mean quick multiplications and back of the envelope calculations. These calculations will help show that you are smart and quick and can come to a conclusion quickly. Also you will always be able to back up any solutions you come to on the job with a quick calculation or some sort of similar derivation. Also being able to calculation rough derivations to prove you understand what is going on and what needs to be done to fix it. That is all. Know your calculations!

Tip #8: Stay Current

Another problem I have noticed with many engineers is that they do not stay current. Here are a few quick easy ways to stay current:
-Read Scientific Journals
-Reread old material from school
-Buy at least one handbook for what you are doing (e.g. Albright's Chemical Engineering Handbook)
-Keep update on what is going on in the world (e.g. Digg's science section)
-Take online courses or go back to school
-Read free online courses (MIT's website)

There are many more ways to stay current and as I come across them I will spread the word!

Tip #7: Find The Job

Here is a quick run over on how I found my job:
-Craigslist: This is the best resource to get your resume out to multiple areas. All craigslist requires is one resume that can be across multiple cities. There are also so many different companies now using Craigslist to reach a potential worker. Responding to these ads had the highest reply rate for me. I believe this is because it takes a more personal approach to reply to Craigslist ads. Make sure to always respond to the information in the ad in your initial email.
-Indeed: www.indeed.com is the singles greatest search engine and resource for finding a job. Indeed will constantly search all of the other job sites and email you updates how ever frequently you want. I used this site to constantly keep update on new job postings.

When replying to a job post:
-Make sure to tailor your resume to the job listing.
-Make the initial email short and to the point. Make sure to respond to the job list.
-Do not use a generic response or email.

Tip #6: Green Engineering

One big aspect of being an engineer and especially and chemical engineer is what can you do for the environment. Every process that a chemical engineer works with, tries to optimize or create MUST be environmentally friendly. A chemical engineer must work with his company to develop practices, products and services that have a minimal (or hopefully positive) impacts on the environment. Also, green chemical engineering refers to the application of impact minimization principles to chemical processes. There are increasing demands for chemical processes that are inherently safer, environmentally sound, economical, and flexible enough to withstand market changes. Engineers of green chemical processes redesign current industrial and laboratory methods in order to adhere to the principles of green chemistry, including:

—waste minimization
-water minimization
—reduction or elimination of hazardous or toxic solvents and compounds
—renewable, recyclable, or recycled materials
—increased energy efficiency of processes
—increased use of catalysis to reduce materials
—increased use of biodegradable materials

Right now, being a "green" engineer mostly involves green house gases or carbon sequestering. There are quiet a few companies that are working on new processes to turn green house gases into usable products. These "green" companies are creating the next bubble and will continue to be a big part of the economy. As these "green" companies finalize their process and get more government funding there will be a high demand for "green" engineers. So becoming a "green" engineer will both be good for the environment and make you a high-demand engineer!

Tip #5: Data

Data is the one of the most important part of being a chemical engineer. I cannot emphasize enough the importance of quality of data. Many data sources such as books, on the Internet or in scientific journals are inaccurate or simply wrong. This can be due to problems with experiments, errors in processing measurements, misuse of extrapolation or estimation techniques, or something as simple as a copying error. For a chemical engineer to be a responsible engineer (which they must be!) the goal is not to just get a number but get a reliable and repeatable number. Obtaining reliable physical and chemical property data requires evaluation of data. This involves expert evaluation of experimental techniques (including sample purity), consistency tests, comparisons among multiple data sets and multiple measurements for the same substance, and other factors such as trends within chemical families.

In order to be a better chemical engineer, the engineer must be responsible and make sure to get reliable data that is both accurate and repeatable.

Tip #4: Process Engineering

I can admit that I am no expert on Process Engineering, but I can give you a little insight into what I have learned so far:
-Understand the medium (liquid, gas, solid or mixture) you are working with.
-If the process is a know process read all the literature!
-If the process is a new process read any process literature related to the process.
-Reread your Process Engineering book.
-Ask questions.
-Do a refresher course on any important equations and constants that will be used in your process.
-Understand the P&ID.
-Recreate the P&ID so you will unerstand where everything is coming from and what it goes.
-Material Balances. They are key! Know what goes in and what comes out.
-Run simulations.
-Track data
-Track trends
-Does the data makes sense? Compare to simulation.

Here is a website I have found helpful
http://www.cheresources.com/process_engineering.shtml

Well that is all I can think of for now. More to come as I learn!

Tip #3: The Resume

Here are some tips I have picked up so far. A resume is one of the key elements of success in being an engineer and landing your dream job.in an engineering job search. An effective resume must grab the attention of the reader quickly.

Background
The good engineers are good at getting the basics of their projects and experience down on paper. However, most engineers are not as good at showcasing their talents on paper. I will provide you with 10 tips from my experiences to help you make your engineering resume get you the interview you want.

Format
There are two big differences for formatting: Chronological versus Combination. With chronological, everything is set up in reverse time order. Combination is a balance between skills, achievements, and employment history. I prefer combination because it allows the resume to highlight projects that define the work you have done.

Objective vs. Summary
I believe you should always write an objective even if the company does not ask for one. With the objective you can show the company that you understand what the job is asking for and that you want it. Some people believe that instead of objective, you should provide the reader with a brief summary which touches on the requirements of the kind of job you are applying to and how your skills and experience meet those requested by that position.

Put the most important information first
In most cases, your previous work experience will be the most important part of the resume, so put it at the top. When describing your experience or skills, list the the ones most relevant to the position you are applying to.

Add a Project List
Depending on your engineering specialty and years of experience, you may find that a dozen or more key projects might have to be included on your resume. I haven't done this yet, but many people are talking about how this will help your resume.

Use Power (Buzz ) Words
Buzz words are scanned for nowadays by some companies to separate those worthy of human contact from those that will be shredded. The computer is fed a list of words that it should look for on any given resume. The resumes with the correct buzz words are passed onto the human resource department. Thus, a great strategy that is extremely important is finding these power words or verbs that match the level of position you want. To achieve this, you must tailor your resume to every position you apply for.

Make absolutely sure your document is error free
An error in a resume can often be the killer between two closely matched candidates.

Find a balance between wordiness and lack of detail
Employers need to know the details about your work history and engineering experience, but they don’t need to know everything.

PDF vs. Word Format
I always sent my resume out as PDF file unless the company specifically asked for a Word Document. I did this because I assumed that my resume would be viewed on a computer screen rather than on a piece of paper. PDF files look more professional and if the interviewer needs to see a hard copy your resume can still be printed out.

Think “accomplishments” rather than “job duties”
What made you stand out from the crowd with your previous experiences? How did you come up with a way to do things better, more efficiently, or for less cost? This type of thinking will put your resume at the top of the list.

Sell the Benefits of Your Skills
Sell what you can bring to the company and what makes you stand out.

Keep it positive
A resume is just a way to sell your to the company. Remember to always focus on what the company wants, people who can contribute, have a positive attitude, are enthusiastic, and have successfully performed similar job skills in the past.

There you go. I hope my tips will help you land that dream interview!

Tip #2: Know the Process

This is very important because you are an engineer and you need to know the details of the processes you will be working on. First thing you need to learn is a P&ID program. This will allow you to create a P&ID (piping and instrument diagram) of the process or a flow diagram of the process you will be working on. I currently use Microsoft Visio and I would recommend it to anyone. The best way to learn a P&ID program is just to pick it up and learn it. I learned myself by creating a P&ID of a unit operation for the plant I was working at. I traced the lines and noted everything in the process (lines , pumps, valves, heat exchangers, tanks and other important units) in a notebook and then I took to recreating it in the P&ID program.

Creating the P&ID will help you understand the process. Once you know the process you can begin to work on improving the process and then you will be on your way to be being a better engineer.

Tip #1: Practicality

I will start off with a quick tip that I learned very quickly. If it is not practical no one will ever want it! So every time you come up with an idea make sure it is practical! I cannot stress this enough that so many times I have run into new ideas or concepts that on paper or theory look and sound wonderful but in the end have no real practical use.

So when conceptualizing anything always think first: Is this practical? Will it improve on anything in a practical way? Can this actually work in the real world?

This is just a quick tip. Don't forget!

Welcome!

Hello All!

This is going to be my blog/tips/whatever for chemical engineers. I have noticed through my time as chemical engineer that there is not much out there for us. So I thought, why not put together a blog of my experiences and tips I learn on the way. This will pretty much be an experience/trips for chemical engineers. I hope I can be of some help to others and will also help me!