Picture Pump Efficiency in Terms of Trees and Cars

When it comes to pumping systems, efficiency must be viewed in terms of measurable savings (kilowatts, horsepower) and taken as a whole-system approach. Organizational buy-in and leadership support are crucial. To help us understand how best to achieve efficiency, Chemical Processing chatted with Dr. Gary Dyson, managing director of global engineering at Hydro. Dyson is responsible for thousands of pump designs carried out on upgrades and new equipment. This is an edited version of that conversation. 

Q: You have written several pieces equating efficiency with reliability. Can we talk a little bit about that?

A: There's only 20% of pumping equipment out there that operates at its best efficiency point. At the best efficiency point, which is really the design point of that equipment, vibration is the lowest, heat generation is controlled and managed, and the equipment should operate most reliably there. But it's not just about the pump, it's also about the system it's in.

So, you can destroy other components of your system by making a pump operate away from the best efficiency point. It may cause you to change the system resistance by closing a valve more, and then the valve cavitates, and that destroys it. So, a system approach is important, and that will get you the most reliable piece of equipment. It's not just the pump, it's the pump in the system.

Q: So, it's essentially that creeping change that can impact this type of efficiencies. And that's surprising, only 20% are running at the best efficiency point. It's a moving target, right?

A: It's a moving target, yeah. What's happened over the years, particularly in the oil and gas industry, a lot of the process industries, when plants were designed and developed, things change over time, but the equipment generally isn't replaced or isn't modified. So as things change in the process and new processes come along, the pumps stay the same. You tend to see pumps push back on their curves away from best efficiency point.

I've seen a lot of equipment, a lot where simple changes to the pump design will warrant brilliant, brilliant process improvement and also let you run the pumps for less time, so saving power. There's an enormous amount of opportunity out there to save power on pumps.

Q: What about maintenance? How does that factor in regarding energy efficiency?

A: Maintenance is important, and every time I go into a plant, I can tell how well-maintained the equipment is just by looking at it. You know when people care about their equipment, and you can see it when you visit the plants. Those plants tend to be more energy efficient. And you know that when you have a piece of equipment that's operating where it's comfortable operating, things that commonly fail last a lot longer, things like bearings and seals last a lot longer when you operate the equipment properly. Maintenance is an important aspect.

I like to think of things holistically. When I think of the lifecycle of the pump, there is the initial cost, which is quite high, but in terms of a percentage of the lifecycle, it's quite low. And then the other things, the recurring things are the power you use to run the pump and the money you spend pulling it out of service, putting it back in service, replacing parts. And though that maintenance side can be quite expensive — particularly if it's unplanned — if you have unplanned maintenance in a very critical process for the revenue of your plant, that's a really big deal.

Q:  I assume, and maybe incorrectly, that the bigger companies can get the maintenance right. What about smaller companies? How do you stress the importance of maintenance?

A: It’s not just the small companies. What tends to happen and what has happened, a lot of plants have been around a long time, 40, 50, 60 years. And that tribal knowledge of the people that have been there has started to dissipate as they've retired, and new people have come in. Record keeping's not that great. And sometimes I think I feel like I'm a detective. I feel like Poirot sometimes because I start to look at the geometry, and I have to work back from the geometry we've got to try and figure out how we got in this situation in the first place, and then figure out what we need to do to change the pump geometry to be in a much better place.

Q: What is the most challenging part of starting these projects?

A: I think buy-in is really important. And I understand it's a difficult conversation for an organization to have because they've got critical pieces of equipment in critical processes that sit directly in the revenue chain. So, if you take a critical piece of equipment out of your revenue chain, you lose a lot of money very quickly. 

But in the longer term, the payback periods are becoming shorter because processes have driven the equipment away from its best efficiency point, and the power savings have become much more realizable because the cost of energy has gone up.

Q: How do you prioritize projects? 

A:  I have a little chart in my head. On the X axis, it's how easy is it to do? Is it easy to hard? And then how much of a savings? Are the savings high or low? Then I look for the things that are on the left-hand axis up, so things that are easy to do where the savings are high. I don't start with the things that are high savings but are hard to do.

I also look at risk. So, what's the appetite for risk? How risky is it to do? Is it going to be right the first time? Is it easy and risky, or is it hard and risky? So, I like to have those two charts in my head and evaluate each potential project on that basis.

Q: You often hear that energy savings initiatives are an investment for the future, but you have shown that this investment pays off rather quickly in the short term. How so?

A: We've had some fantastic projects in the Middle East. I know it's not the most environmentally friendly process in the world, but we are still going to have to deal with oil for the next few decades. So, producing it in the most efficient way is important.

And we took a system view on some pipeline pumps in the Middle East, and these were big high energy pipeline pumps, and we looked at where they were operating versus where they were purchased to operate. They were purchased in the 1980s to do a certain amount of oil shipment. And we looked at where they were operating now, and what we found was that the demand from these pumps had changed, and they were generating far too much pressure, and then they were breaking that pressure down over the control valve.

What we were able to do was rerate and change the impeller and rotor design of that pump in situ. We didn't have to change any of the piping, we could just change the internals of the equipment, and we could make it so that the valve was open and that they pumped against a more open valve. So, we didn't throw away any pressure, that we generated across that valve. We did three pumps, and over those three pumps, we were able to save a $1 million in power consumption a year.

I don't like to do the dollar thing because there's international views of how much power costs, but really it's country specific. What we've started doing is looking at how many trees you would have to plant per year to offset the carbon of that power. And that was 450,000 trees you'd have to plant to offset the carbon we saved. And 70,000 cars you'd have to take off the street if you wanted to offset the carbon.

I like to use those analogies because they give people a good picture of what you have saved. But the great thing is the customer has actually saved a million dollars from his generating capacity that he was previously putting through the pump. So it was a fantastic project.

That was a landmark project for us, and the oil company was brave enough to let us do that project. That filtered down right through the organization — we've done probably another 20 projects in the Middle East, saving millions of dollars. I think we've saved more than $10 million now in terms of power consumption.

In another project, we looked at high-energy equipment. I always like to start with high-energy equipment because the opportunity to save is bigger. We looked at the whole system, and the pump was operated by a fluid coupling. Fluid couplings were used in the Middle East because the electrical grid wasn't that strong, so it was easier to use a fluid coupling between the motor and the pump.

But the big downside of a fluid coupling is when you slow your pump down using the fluid coupling, you don't really reduce the energy. The energy required from the pump goes down, but the energy sort of put into the fluid coupling stays the same, so the efficiency goes away.

We were able to change the internals of the pump so that it could operate at its maximum speed through the fluid coupling. The fluid coupling efficiency went from 60% to 85%. Landmark projects like that really help, and they really help the organization. So we're now moving down to lower opportunities in terms of power, but still, it all adds up to great savings.

Q: Is there anything you want to add?

A: The world is waking up to the environmental opportunity we have in equipment and modifying and changing equipment to consume less power. We've got a new generation coming out of college that is much more attuned to the needs of the environment and cares about it. People want to work for organizations that care about the environment, and so people will look for those positions. So over and above the equipment, I think attraction and retention of people is going to be key to everybody in future. So having an environmental program and a process of reducing your impact on the world is going to be a very important thing.

 For more information, visit https://hydroinc.com