A Smarter, Unexpected, Look At Blower Efficiency

Tom McCurdy of Aerzen explains the importance of choosing the right blower technology, and how high-efficiency products and “turbo-mania” have led consumers astray.

Todd Schnick: Good afternoon and welcome back to Water Online Radio, coming to you live from WEFTEC here in New Orleans, Louisiana. I am Todd Schnick, joined by my colleague, Todd Youngblood. Todd, we have a handful with this next fellow.

Todd Youngblood: I am going to talk to the schedulers about putting guys like this in the afternoon.

Todd Schnick: This final stretch has been very very interesting. I am excited to welcome to show Tom McCurdy, who is a Regional Sales Manager of Water Wastewater Treatment for Aerzen. Welcome to the show, Tom.

Tom: Thank you very much. Thanks for having me.

Todd Schnick: Oh, it is our pleasure, Tom. Before we get into it, do take a sec and tell us a little bit about you and your background.

Tom: Okay. Well, I am a mechanical engineer graduated from Rutgers back in 1981.

Todd Schnick: I heard it. 1981.

Tom: Thank you.

Todd Youngblood: 1981. Are you going to tell him when I graduated to make him feel better?

Tom: Common.

Todd Youngblood: ’75, baby.

Tom: Excellent. Excellent. I worked for Ingersoll Rand for a few years and then got into the water treatment field selling for Betz Labs Water Treatment Chemicals, but that is really where I learned all about wastewater.

So my job now with Aerzen as a Regional Manager in the water and wastewater division sort of culminates all my previous experience together with you knowing about the wastewater industry, a little bit about the technology, and certainly knowing about the machinery that we sell.

Todd Schnick: Well, let us go deep on Aerzen. Tell us all about the organization. What do you do? How do you serve your market?

Tom: Aerzen is a company that has been around since 1864.

Todd Schnick: Wow.

Tom: Yeah. We have been in the U.S. for about 30-some years based in Coatesville, Pennsylvania, just outside of Philadelphia.

Todd Youngblood: I grew up in Quakertown.

Tom: Ah. Well, there you go. We provide blowers, primarily low pressure air movers. For WEFTEC’s purposes, it is all for wastewater, for aeration – a number of purposes in a wastewater treatment plant.

Pretty much 60% of a wastewater treatment plant’s electric bill is from the blowers, from the power required for the blowers. So efficiency becomes a very big factor.

Todd Youngblood: That must have some implications in choosing the right kind of technology for that aeration?

Tom: Yeah, absolutely. Absolutely. And you know it is interesting because the turbo blowers, these high-speed turbo blowers that are out in the market –they have probably been out for five years, but there was a turbo-mania out there where it was basically the only alternative to PD blowers, and so much more efficient.

Unfortunately, I think they just ended up getting over applied. They just tried to slot them in everywhere, but yes, efficiency becomes very important. But it becomes even more important to choose the proper technology for the application that you are providing the air for.

Todd Schnick: So it is not more important to have the most efficient technology?

Tom: It is important to have the efficient technology, but it really depends on how that blower is used. For example, there is a process where the blower is used in filter air scour, where the blower air is used to sort of assist the backwash and fluffing up the bed and getting the debris out of the filter media. But those blowers only may be operated for an hour a day, so there really is not much electrical usage for that type of blower. In those cases, you sort of just slot it into the standard PD blower, where you are just going for capital cost.

Whereas, in the other applications: aeration, sludge digestion, post-aeration – anything where it is a continuous process – it becomes very important to factor in the efficiency and the overall life cycle cost, because you are expecting a blower to last 10, 15, 20 years, and the amount that you pay in the capital cost on the front end really pales in comparison to the power cost over its lifespan.

Todd Youngblood: You said, I believe, 60% of energy cost is in the blowers alone?

Tom: That is about right.

Todd Youngblood: Okay, what kind of impact can choosing the right technology have in terms of dollars and cents?

Tom: Well, it can have a big impact. If you talked to a consulting engineer, they would say that blowers are just about one portion of the overall scheme.

There are more efficient diffusers and more efficient overall systems that add to that efficiency, but if you look at the overall impact, for all you changed ou with the blowers themselves, you could conceivably save yourself anywhere from 20 to 30% on your electric bill.

Todd Youngblood: That is a big deal.

Tom: It is a big deal, and the power for those aeration blowers is probably the biggest chunk of a wastewater treatment plant’s overall cost. My understanding with the municipal plant is that the three biggest cost centers are the power required for the aeration air and all the other air in the plant, the sludge disposal, and personnel.

So we are right up there for one of the biggest costs in the plant, so choosing the proper blower technology from an efficiency standpoint and from the appropriate technology standpoint become very important.

Todd Schnick: We talked about efficiency, but what other factors enter into the evaluation?

Tom: Well, when you look at the various processes that are out in a wastewater plant, each one of them has characteristics that either favor or steer you away from the different technologies that are out there – for example, an SBR system, one of these sequencing batch reactor systems, where the water level can vary quite considerably. It is especially true on a sludge digester, where the level can vary all over the place.

If you went in with a turbo blower, you would have to make sure that the high level and the low level, that both correspond to the appropriate pressures there, were on the characteristic curve of that particular turbo.

Whereas with either of the PD technologies out there – the standard rotary low positive displacement blower or the screw compressor – it really just comes down the motor horsepower, because it is a different type of technology.

The turbo technology is the very dynamic technology where it basically grabs the air, flings it out to the edge of the impeller, and that velocity that gets imparted on it turns it into pressure.

Well, doing that is a different process. It is a very efficient process, but it may not factor in with where it is being used. So if you have a turbo blower and you have got a wide range of water depths, you really run the risk of it being misapplied.

Todd Youngblood: I have been thinking in terms of choosing the right technology and I am wondering, is that the right question? Should I be thinking in terms of choosing the right technologies? Should I have different types of technology in one plant perhaps?

Tom: You probably will have different types of technologies in one plant. I had mentioned before, for the air scour blowers, it is very likely just going to be a standard PD blower.

So within a wastewater treatment plan, you will have air scour blowers, you will have aeration blowers, you will have digester blowers, you will have post-aeration blowers, you will have a number of different other blowers.

So to have a mixture of different technologies in the plant is almost a given, but even within one particular application, there is that potential to mix those technologies, but you have to be very careful about that.

The idea of having a turbo blower take the base aeration load of the plant so it can run in its sweet spot is a good thing from a technical standpoint. But in applying that in the plant, you have to take into account what other factors are in play.

The idea of possibly mixing those technologies to use turbo blowers at the base load and maybe a screw compressor to take all the swings is a good idea, but it has to be done carefully so that you do not throw off the operation. Especially on the turbo, which is a little bit more sensitive to pressure fluctuations.

Todd Schnick: Tom, I hate to say it but we are out of time. Before we let you go, how can people get in touch with you and where can they learn more about Aerzen?

Tom: Well, the first and best place would be to go to the Aerzen website, which is www.aerzenusa.com, and you will find a whole list of contacts – my contact information included – and you can download a guide that we have.

We have a Mini-Guide to technology selection, and if you get a hold of myself or my counterpart, we can direct you towards the proper manufacturer’s rep. We have got excellent relationships with those reps; they are well educated on our products. So we can go from there.

Todd Schnick: Tom McCurdy, Regional Sales Manager of Water Wastewater Treatment with Aerzen. It was great to have you. Thank you so much for joining us.

Tom: Thanks for having me.

Todd Schnick: All right. That wraps this segment for Water Online Radio, live from WEFTEC in New Orleans. We will be right back.