The segment from WaterOnline Radio features interviews with John Franz, wastewater treatment plant manager for the City of Anacortes, WA, as well as Kevin Grant, a regional sales manager for Aerzen USA.
- How Aerzen aeration blower efficiency is saving a Puget Sound utility an estimated $44,000 per year.
- The energy and O&M gains offered by new blower technology.
- The difference between positive displacement, turbo, and hybrid blowers.
- How to manage air demand to find your efficiency "sweet spot."
Listen To The Podcast:
Here's a sample of the conversation with John Franz:
Water Online Radio: John, there are a lot of organizations that you could have worked with to get more energy-efficient machinery. Why did you go with Aerzen?
John Franz: That's a really good question. At the time we started looking at this project, a very popular way at wastewater treatment plants to achieve this savings was to go with one of the new turbo blowers. The new turbo blowers are very efficient machines, and there are a number of them that have been installed and were operating successfully.
People were really quite happy with them. When we started talking to vendors about how to analyze this and how to select a piece of equipment, we came across Aerzen company, and they had a really new technology that they called the hybrid blower.
That machine, when we examined it and compared it to the turbine blowers, it was just a little bit more efficient than a turbine blower. But more important to us, it had a broader range of operation.
...and with Kevin Grant:
Water Online Radio: Kevin, Aerzen likes to say, “We deliver performance to the power of three.” Talk about that.
Kevin Grant: Traditionally, Aerzen started out being a rotary-load positive displacement blowers, also known as PD blowers, which are generally the workhorse of the industry and traditionally, the technology started back in the 1860s, but we also have the turbo blower that we've introduced into our product line, which is not a positive displacement.
It's like centrifugal technology, and it's a high-speed, high-efficiency unit. Traditionally, in this market, there's things called multi-stage centrifugal. This is a single-stage high-speed. It works off of air oil bearing, so there's no oil in the machine, and uses a permanent magnet motor and an inverter to get to speeds 30,000 to 40,000 rpm.
That's one technology. The PD is the other technology, and then, like I said, Aerzen started developing about 12 years ago a new product they call the hybrid, which was a cross between the single-stage oil-free screw compressors and a PD.
Basically, it combined the efficiency of a screw compressor, but with the economy of our PD blowers. Between the PD, the hybrid, and the turbo, that gives us three different technologies that we can approach any application or any problem. That's where the performance of three comes from.
A biological municipal wastewater treatment plant with a considerably fluctuating discharge quantity can only perform its function with utmost energy efficiency and reliability if the process air consumption of the aeration basin can be adjusted continuously and is fully automated in order to deal with widely fluctuating load quantities. The example of the wastewater treatment plant shows how this is achieved with the use of a speed controlled Aerzen turbo blower.
The sewage treatment plant in Bremervörde was designed to have an overall capacity of 30,000 EGW (population equivalents) and with approx. 29,000 EGW it is now nearly at full capacity. At present, up to 3,000 m³ waste water are fed into the sewage treatment plant every day. However, approx. 1,200 up to approx. 1,500 m³ can be generated by one single production, the quantity fluctuates particularly due to the rest from work on weekends. The amount of wastewater generated by the resident population in the catchment area in the course of the working week with approx. 1,500 m³/day is nearly constant.
View into the blower station of wastewater treatment plant Bremervörde. At the front the AT-turbo blower, behind it two positive displacement blowers Delta Blower, with which process air for the aeration basin (small photo) is generated.
It is obvious that a wastewater treatment system with a wastewater spectrum of 50 up to 100 per cent can only be run with optimal energy utilization when the selected process air generators adjust fully automatically to all the requirements. Sewage work operator Heiko Müller says: “Therefore in November 2010 we realized a new concept for the generation of process air. Currently, one new speed-controlled Aerzen turbo blower as active base load plant covers, by itself, our process air requirements across the entire spectrum.
When so required, we can switch in addition two older model fully automatic positive displacement blowers for generation of the peak load. With this well-tailored distribution of the base load onto an accordingly dimensioned turbo blower and the peak load onto up to two positive displacement blowers we are now operating our process air station particularly energy efficient. The subject ‘energy costs’ is for us extraordinarily important, because for the process air generation we have to spend about 75 per cent of the total energy costs of our wastewater treatment plant.”
Larger control range
Already in the more distant past the process air for the aeration basin was generated by means of positive displacement blowers made by Aerzener Maschinenfabrik. These old units were replaced in 1999/2000 by two Aerzen blowers series Delta Blower. One unit covered the requirement, the second one served as redundancy. Both units were already speed controlled, so that they could be adjusted to the fluctuating requirement in a range of between approx. 35 and 50 Hz. However, in their lower performance range the blowers could not cover anymore the even lower load requirement.
Therefore, supplementary units had to be found for Bremervörde’s process air generation requirements. These had to be speed controlled on the one hand and to have a wide performance spectrum on the other. Additionally, if possible they should be able to run 100 % in speed-controlled load-run operation across the entire requirements spectrum.
New Aerzen AT-turbo blowers
In November 2010 a new Aerzen turbo blower type AT 100 – 0.6 (driving power 75 kilowatts) was installed. Since it was commissioned the unit has run 10,700 operating hours (as of February 2012) and consequently ran almost entirely without no-load operation periods around the clock in volume controlled load operation – which proves its optimal design. This unit, with a capacity spectrum of 36 up to 80 m³/min, now serves as base load generator for process air supply of the wastewater treatment plant in Bremervörde.
The two Aerzen positive displacement blowers of the old supply concept can be connected automatically as stand-by units and as peak load generators. As per information from Heiko Müller about 75 per cent of the electrical energy used in the Bremervörde wastewater treatment plant is used for generating process air. Therefore for the new concept the particularly economical handling of electrical energy was an absolute precondition.
Heiko Müller, sewage work operator at Bremervörde "We are convinced that with the present combination with one turbo blower for the base load and two positive displacement blowers for peak load and stand-by, we have realized an ideal and very recommendable concept."
Before making the decision to purchase they had determined that under consideration of the available depth of the basin a discharge pressure of 0.4 bar is sufficient for optimal aeration. Onto this value theimpeller of the blower was customized for the highest possible energy efficiency. Higher pressures up to max. 1.0 bar are possible by using corresponding impellers.
All three units, the new Aerzen ATturbo blower as well as the two approx. 12 year old Aerzen positive displacement blowers series Delta Blower, were installed optimally in a separate building. The supply air enters from the outside. A filter mat prevents dust from penetrating into the unit. Warm exhaust air supported by a fan escapes the room. All the units supply via a busbar in the station directly into the aeration basin. A probe in the basin continuously measures the oxygen content and controls the delivery volume of the process air via the speed of the units. At the end of the treatment process the treated water is discharged into the adjacent river Oste with a purity degree of approx. 95 per cent. “With this concept we meet our requirements optimally and with highest possible energy efficiency. The turbo blower works with its broad performance spectrum as ideal base load unit in spite of our widely fluctuating input quantities between 1,500 and 3,000 m³/day. Depending on the requirements, the Aerzen positive displacement blowers can be connected fully automatically as peak load units”, says Heiko Müller and continues: “With our new concept for generation of process air as per our experience we found an optimal solution with highest possible energy efficiency. Our expenditure on maintenance amounts to just a few minutes a year for changing the filter mats.
The AT-turbo blower at the front generates the base load – the positive displacement Delta Blowers behind generate the peak load.
And the specialists from Aerzen guarantee an optimally adapted overall concept. We are convinced that with the present combination with one turbo blower for the base load and two positive displacement blowers for peak load and stand-by, we realized an ideal and very commendable concept. With this we can supply our biologically working wastewater treatment plant and make it safe to operate, reliable and especially energy efficient with process air.”
Due to a new bearing and shaft design it is possible to increase the maximum admissible differential pressures to 25 bar in the process gas compressors VRa 236 H and VRa 336 H. Thus, with a multi-stage unit discharge pressures of up to 53 bar abs. can be reached.
Considerable cost savings and reductions in space usage are possible as higher pressures with fewer individual compressors and corresponding accessories can now be achieved. Moreover, the new types of the H-variant can ideally be used for pre-compressions. Customers in the chemical, petrochemical and processing technology industries can select the compressor unit optimally for their needs from one of the most extensive ranges available. Particularly in the case of multi-stage applications there are ideal combination possibilities which also offer advantages in volume control. With a total of 20 compressor stages, the Aerzen process gas machines cover intake volume flows of from 550 up to 120,00 cubic metres per hour.
One of the new process gas compressors with a view of its inner workings
Practically all gases are compressed, if contaminated, polymerised, supplied with liquids or with low molecular weight. In the case of single-stage compression, differential pressures of between 7.12 and now also 25 bar but also vacuums smaller Pe up to 0.9 bar can be realized.
The Aerzen Process Gas Compressors consist of an extensive modular system which can fulfill many different requirements using special and individually designed units. Building regulations and specifications of various industrial branches and inspection companies such as API or works standards are considered customer-specific. For adaptation to many different situations, process gas rotors can be selected in steel or stainless steel and housed in a nodular iron, steel or stainless steel casting.
The Aerzen modular system offers carbon labyrinth as well as oil-and gas-purged mechanical seals for the sealing of the conveying chamber, which can be selected without modification of the housing design. The same applies to most of the different driving methods. Whether direct drive, drive via an intermediate gear, or by electric motors or by steam turbines, the application of proven components ensures maximum possible safety and reliability.
The successful process gas compressors VRa of Aerzener Maschinenfabrik GmbH have been extended by new sizes. The innovative types VRa 236 H and VRa 336 H supplement the compressor series in the lower volume flow range of from 750 to 2,800 cubic
metres per hour.
Three main blower technologies are condsidered for waste water treatment applications:
- High-Speed Turbo Blowers
- Hybrid Blowers (Rotary Lobe Compressors)
- Positive Displacement Blowers
To determine the best one for a WWTP application, Water Online conducted a radio show featuring Tom McCurdy from Aerzen USA to get the latest insights and approaches to choosing the best technology.
Now Aerzen has all three technologies and is the only one who is actually combining them together to get even more energy efficiency in waste water applications.
Listen to the radio show and then download the Engineer's Mini-Guide To Blower Technlogy Selection.
Turbo Blowers. Positive Displacement Blowers. Hybrid Rotary Lobe Blowers. Which one should you choose for your wastewater treatement application? How much energy can you really save? Who can you trust to give you an objective answer? The best place to start is by downloading the Engineer's Mini-Guide To Blower Technology Selection.
In the mini-guide there is a quick, five step process that will lead you to the best technology for your needs.
- Step One: Takes you through a brief "Life Cycle Evaluation"
- Step Two: A look at Pressure Differential
- Step Three: Duty Variables
- Step Four: Right Sizing Of Individual Blowers
- Step Five: Representative Energy Use Calculations
A simple table is presented at the end of the guide for you to add-in specific information for your application. There is contact information listed if you need to speak to an Application Specialist for assistance as well.
This quick - two page pdf makes it easy and effective to determine which blower technology you should consider. Turbo Blowers. Hybrid Blowers. PD blowers.
Want to get even more energy efficiency? Talk to an Application Specialist about COMBINING a Hybrid Blower with a Turbo Blower.
The Aerzen iAir Remote Monitoring System (RMS) is a comprehensive monitor that can be attached to any blower or compressor to capture real-time activities and conditions. Based on industrial cellular technology, the RMS can function in any location with cellphone coverage for both indoor and outdoor applications. The system is easily installed and linked directly to your cell phone for up-to-the-minute condition reports and notifications. This allows for peace of mind and troubleshooting when you are not accessible to the equipment.
Perfect for independent installations with no on-site maintenance personnel.List of applications:
Remote terminals for Cement processing
Critical blower or compressor installations
High value equipment performance monitoring
Root cause analysis & system
Note: Unit is not rated for use in hazardous zones.
Monitor operational data and parameters:
Inlet & discharge pressure/ temperatures
Oil level, pressure & temperatures
System pressure, RPM & overall vibration
Electric load and more
Equipment monitoring and full reporting analysis from any location
The iAir Remote System reviews the actual usage of the equipment and sends alerts and reminders via text or email directly to the user. Log on anytime for a real-time report to make maintenance and emergencies more manageable.
Call A Remote Monitoring Specialist To Discuss Your Application: 877-673-0499
Shipping damage is the top number one issue followed by scheduling and only then cost. It is amazing how much freight gets damaged per year. This is particularly true for new blower packages that are shipped via LTL (Less than truckload) and so called common carrier. Although deemed the most cost effective – expediting and broker companies managed to push the cost down - it is the most difficult way to get machinery to a job site undamaged. Because freight must be consolidated in the carrier’s main hubs the equipment must be moved often. The mostly heavy and odd shaped freight with uneven weight distribution is moved with fork trucks that are significantly undersized. Making things worse is the fact that logistics is a business model where people make Cents on a Dollar and thus the time freight spends in non value adding moving around within terminals is kept to an absolute minimum causing fork lift drivers to drive fast and furious. Freight gets shoved around, stacked (when it should not be) and dropped rapidly (giving drop-shipment a different meaning). The result is that sound enclosures, castings, instrumentation etc gets damaged significantly before it even makes it to the final destination.
Here is a brand new unit that was literally “drop shipped” – it fell off the lift truck during the off loading process at the job site.
FTL (Full truck load) shipments do not fare much better. Here the truckers often get completely carried away by putting the tie down straps way too tight on the sound enclosure roofs resulting in dented and crushed panels. Some leave with promising that they will tarp the freight when they get the next best change. You guessed right, this more often than not does not happen at all – now there may be rain and road water in places where this would normally never get to and now creates a major start up issue. Inexperienced drivers hit bridges and trees with the new equipment and some manage to completely drop the machines off the trailer.
Here the straps are being put on way too tight.
Here is a unit with “tree damage” – the unit was struck by a tree inroute to the site.
Addressing these issues cost a lot of money and most of all – time. You will not be able to use the blower or compressor for a while now that key components must be fixed. While most freight companies are pretty good about financial compensation, it still puts the burden on you the customer to make sure to either not take damaged freight off the truck, but at an absolute minimum make mention on the bill of lading that there is a problem with the freight. This helps alleviate the debate with the carrier later and speeds up the damage claim. Scheduling the pick up at our facility or even just making sure the correct truck shows up (needing a drop deck trailer when a regular one shows up makes for interesting calls) is often beset with issues. One example had a trucker show up no fewer than 5 days late because he had other drop offs to make. Is this worth the money that you thought you could save?
Best choice would be to let Aerzen handle the freight. Sure, sometimes this is more expensive, but we have aligned ourselves with people that will make sure your freight gets to the job site in the great shape you expected. The worst case had a good OEM of ours insist that his broker be used with the result that the very same blower packages were damaged twice and needed to make the trip toFloridathree times of which the last trip was with our house carrier. This is another life lesson of pay-me-now-or-pay-me-later.
Got a comment? Please drop me a note.
The majority of all operating manuals provide the equipment user with a time based plan when to change the machine’s oil. This interval is typically designed to protect the oil and subsequently the machine from breaking down prematurely in most if not all operating conditions. So far so good. This comes with a price tag as the machine needs to be properly shut down and locked / tagged out. Besides of the obvious cost for the lubricant you also incur labor and potential production down time cost. For most of the smaller machines requiring less than a gallon of oil for each change it may not make sense to go with a condition based lubricant change. Experts fix what needs fixing and this applies here also. For larger quantities it may make much more sense to go with an oil condition based oil change schedule.
First ponder what constitutes a “larger machine” for you. Prioritize by amount of oil and how crucial the machine is to your plant. Then pick an oil analysis company or diagnostic tool that will provide you with a fast oil analysis result. Best are systems that provide an online access with e-mail notification when there are samples that need attention. If the lubricant is still ok, why would you change it? This helps saving time, labor and oil and thus you can do your part to help conserve resources.
Here are test requirements that the analysis should bring to the table:
- Viscosity at 40C
- Viscosity at 100C
- Water content
- ISO cleanliness grade
- Particle count
One company that offers such a service is ALS Stavely at www.alsstavelylabs.com . Important to any analysis is that there be at least twice a year samples taken. Quarterly and for really crucial pieces of equipment perhaps even monthly trending may be warranted. Assuming viscosity, cleanliness, water and oxidation values are still acceptable there is no need to change the lubricant. Going from a time based to a condition based oil change interval is not only great for your budget, but also for the environment. It helps stretch our precious resources too.
Got a comment? Please drop me a note.
Plant air is a known energy sink and you may not think of a shop air compressor as an area that can be made more sustainable. At Aerzen’s LEED certified facility in Coatesville we initially were not able to improve upon old concepts at first either. During the course of the last three years we were able to make significant changes to reduce its environmental impact. Adding an electronic controller, variable speed drive, remote monitoring and recycling waste heat did a fantastic job reducing the carbon foot print of the compressed air system. They are simple ideas that you can implement in one way shape or form. Your bottom line may be affected by this more than you think.
This is a view into the sound enclosure of the Aerzen compressor package.
One improvement that anyone can make right from the time to look for a new compressor system is to choose a continuous duty rotary screw compressor over a conventional piston compressor. The reason is that you have to quite oversize a piston compressor since they typically are not intended to be run continuously. Also, the piston compressor usually requires a higher discharge pressure to make the best use of the two-point pressure control and / or a bigger air tank. Both of the measures contribute to less run time per hour for the piston compressor and yet this uses more energy than a rotary screw compressor that can continuously operate at a lower pressure.
The 15 year old oil flooded single stage Aerzen rotary screw compressor VMXa0937R had initially been designed for a simple 2 point load-unload compressed air system with a single speed belt drive and a 25 horsepower motor. It was set up with a long minimum run time setting and a digital switch and relay type control panel. Throughout most of its life it seemingly operated all day, and it was never shut off after business hours and the weekends. Using an Aerzen AS200 compressor controller we were able to reduce the minimum and after-hour run time. With a so called weekly operating schedule program it was possible to enter the daily time frames where the compressor was expected to be online. This reduced the operating time significantly because even though our company’s compressed air system’s leakage rate is well below the industry benchmark of 10%, it would have still meant for the compressor to run multiple times overnight or the weekend. Ideally, we could install a smaller compressor that would then be able to operate at a better overall efficiency, because it would operate at a higher RPM. Running a bigger compressor than necessary at a low speed causes for the motor and compressor to run at lower electric and volumetric efficiency.
The next thing we installed was an Aerzen iAir Remote Control monitoring system. This is a system that connects to the controller via industrial cell phone technology and is connected to the central server allowing accessing and trending of the compressor operating parameters. We found out that the compressor capacity was much larger than practical. This led to the installation of a constant speed – constant torque variable speed drive. We were able to reduce the speed to about ½ from max speed and were still able to maintain and never drop below nominal system pressure. This offered a phenomenal power reduction.
In the final step we thought that we could make use of the heat energy that comes off of the oil cooling system. An oil flooded rotary screw compressor puts the gross majority of the heat stemming from the compression process into the lubricant. This heat is removed by air cooled oil coolers and can present issues with the removal of this heat out of a compressor room. Here we installed one oil cooler with fan in our production area away from the compressor room. This allows us using the heat to help heating the production area in the winter months. By ways of using oil system diverter valves we can also put the hot oil through another cooler that is installed on the outside wall of the building. This makes sure we can operate in the summer without having to cool the compressor room, or to put additional heat into the building.
Please see the link below for the quick video showing the key elements for the upgrades.
Challenge yourself by asking how your compressed air system may be improved upon. There is a large amount of energy potential that is currently wasted and thus pulls straight from your bottom line – the power bill often gets overlooked. Please drop me a note in case you have comments, suggestions or questions.
In order to properly size a blower system with a vacuum pump, there are five main requirements to consider:
How fast the customer would like to get to a base pressure in their vacuum chamber?
After they load the chamber, they then have to evacuate it down to certain pressure. This must be accomplished within a given time because, time is money, especially in manufacturing environment.
How to handle the gas load when we get to the base pressure?.
In most cases the roughing system is big enough to handle the gas-load, however this needs to be confirmed.
Examples of applications:
Vacuum coating – may have a flow of reactive gases
Making computer chips to solar panels
How deep a vacuum do they need to get to – what is the base pressure?
What is the rate of in-leakage going to be?
Do we have to overcome out-gassing from the chamber or the product?
The biggest problem that comes up time and again is how far away from the process the pumps are going to be located. In high vacuum applications the pressure drops are very significant. We have to evaluate the line size and diameter as well as if it is possible to get the pumps closer to the chamber to spend less money on the vacuum.
Another key area for sizing the blowers is a matter of modeling the thermodynamics of compression and making sure we avoid a thermal overload situation in the blowers. Rough vacuum systems are the most vulnerable to overheating in the range around 10 torr. Often times we are sizing blower systems for people who already have a primary vacuum pump selected. Sometimes we are selecting the correct size for maximum efficiency and type of pump with respect to process considerations such as condensable vapors or sensitivity to having oil molecules contaminating the product.
Solutions range from various oil sealed types of vacuum pumps to completely dry or liquid ring systems.
To learn more about proper blower sizing visit our website – www.aerzenusa.com or send me an email with your application question.
Vacuum Technology Specialist