man in blue with helmet

Edition 02/2018

Article and compact news


Efficiency gains through modelling

Wastewater technology

It is the activation process which accounts for the lion‘s share of the electricity used in the treatment of wastewater. In energy studies, it is worth taking a closer look at the processes, especially in this case. Armin Meister, and his engineering office, rely on dynamic modelling methods from system theory for the analysis and optimisation of existing systems in wastewater treatment plants. With this structured approach, the physics engineer at the wastewater treatment plant in Bingen has succeeded in significantly reducing the energy requirement through conceptual changes, and the use of modern hybrid blowers from AERZEN. At the same time, the plant‘s elimination performance has increased dramatically. 

The biggest leverage is process improvement

The blower technology can be operated on site via a touch panel.

Pushing processes and the environment forward through modelling: for the wastewater treatment plant in Bingen, which has been designed to cater for a population equivalent of 80,000, this far-reaching approach has led to a considerable improvement and stabilisation of the cleaning performance. The energy savings in the area of activating sludge are divided between conceptual improvements, and the use of better machine technology. “Besides staff costs and maintenance costs, energy costs and discharge values also determine our operating costs,” says Meister. Lower discharge values mean a reduction in the wastewater levies which have to be paid to the national government. Investments therefore pay off twice.

The optimised processes require careful technical design, so that systems can be run as continuously as possible at the optimal load point with the aid of a fast and dense network of sensors. Meister investigated load curves spanning several years, and based on this he designed the modelling. The modelling forms the basis for defining future requirements for the compressor stations. “This made it possible to select the most suitable assembly in terms of energy consumption and overall cost-effectiveness, while ensuring the appropriate technical requirements for wastewater treatment and the necessary redundancy.” This led to the selection of AERZEN rotary lobe compressor, type Delta Hybrid. Here, two air conveying processes are combined in one machine: Root’s principle as full pressure compression for low pressure, and the screw compressor principle with internal compression for higher pressure. Calculations show that the rotary lobe compressor requires up to 15 percent less power than conventional compressors for absolutely oil-free air conveying.

Operation at optimal load point

New meets old: the old-fashioned blowers now serve as redundancy and standby for peak loads.

Four Delta Hybrid machines are required, which cover almost 90 percent of all operating cases, so that the older and less energy-efficient assemblies are only used for rare high-load or redundancy events. In view of the optimal load points, the rotary lobe compressors with graduated capacities and correspondingly adapted motor sizes are used for two independent compressed air systems.

The largest Delta Hybrid rotary lobe compressor, type D62S, with 110 kW motor rating and 1,000 mbar maximum differential pressure, supplies up to 3,500 cubic metres per hour. The D36S, D24S and D12S models are smaller dimensioned and deliver 2,150, 1,390 and 690 cubic metres per hour with motor ratings of 75, 55 and 30 kW respectively. The two smaller assemblies are installed in the engine house, which also houses the older machinery. The two large Delta Hybrid machines are located outdoors. A simple roof protects them from the weather.

Robust design for outdoor use

Two Delta Hybrid machines are placed under a protective roof outside the wastewater treatment plant.

The decision to install the two Delta Hybrid, types D62S and D36S, outdoors, was made for two reasons: not enough available space and inadequate ventilation in the engine house. The Joule-Thomson effect, which occurs during air compression, means that the compressed gas mixture heats up, as the molecules move closer together due to the higher pressure. An increase of 100 millibars results in a temperature delta of +10 degrees centigrade. This increases the required compression effort due to reduced air density and lower oxygen content of the intake air. Installed outdoors, the Delta Hybrid machines can dissipate heat losses much more effectively into the environment and in turn suck in air that is not thermally preloaded.

This correlation has the same effect on energy efficiency as the use of technology tailored to performance. One aspect to consider at this point: the operation of the rotary lobe compressors with a frequency inverter for demand-oriented and thus economical speed control of the drive motor. The four sizes of the Delta Hybrid with their scaled motor rating also make it possible to operate the load points most frequently occurring with optimal efficiency. In addition, the high adjustment range of the Delta Hybrid machines ensures that there are large areas of overlap between the assemblies. These areas are necessary, in order to ensure optimal adjustment of all operating points and stable compliance with the control specifications, even in case of continuous load changes of the system. This is particularly important as the activator basins of the Bingen wastewater treatment plant are not divided into fixed zones for ammonium degradation and nitrification. Rather, the areas of the different biodegradation processes can be variably adapted to the contamination loads by connecting the basin zones and the precise air control of the surface ventilators mounted on the basin floor. 

The areas into which air can be brought, and in what quantity, can be adjusted as required by means of control valves. There is a sliding pressure control system, so that valves, that are closed too far, do not cause the back pressure in the supply pipe to rise. This is based on the optimal interaction of volume flow, flap position and pressure. “Throttles, which are closed too far simply waste energy. 100 millibar more pressure means 20 percent more energy consumption,” the planner explains. “When it comes to improving the quality of a plant, precise, stable control methods, which are tuned to the speed of the coupled processes, are indispensable,” he adds. 
In Bingen, a multi-stage control process operates in the background with pressure control as the leading variable for the compressor adjustment, and with a delay time of about half a minute. The control of the oxygen concentration in activation zones with settling times of about 10 to 15 minutes, which act on the control valves in the compressed air supply, is time decoupled from this. Their position ensures continuous adjustment of the system pressure and thus triggers the above mentioned sliding pressure control.

Compact news

Aerzen USA continues to grow: new office in Atlanta

Following the expansions of the headquarters in Coatesville/Pennsylvania and the opening of a new sales office in Houston/Texas in 2017, Aerzen USA has now opened up in the southeast of the United States: in May 2018, the AERZEN subsidiary inaugurated a new location in Atlanta/Georgia. The new building covers almost 2,000 square metres of production and storage space, as well as an area of 260 square metres for offices. “We are pleased that we are now closer to our customers in the southeast of the USA,” emphasises Tony Morris, Managing Director, Aerzen USA. “The new facilities will allow us to serve important markets more flexibly and efficiently,” he adds.

The space in Atlanta is available for rental machines, spare parts warehouses, assembly, repair and maintenance of assemblies, as well as state-of-the-art test procedures. The new offices are used primarily for sales, and there is space available to accommodate more employees in the future. The site is expected to be fully operational in the autumn of 2018.

AERZEN China at the IE Expo 2018

Aerzen China had a strong presence at the IE Expo 2018, held in Shanghai from 3-5 May, which attracted more than 60,000 visitors from over 60 countries. At Asia‘s leading trade fair for environmental technology, the company presented itself with the motto: Performance3 - The Next Generation.

At the AERZEN booth, prospective customers could gather information about Aerzen Turbo AT300-0.8, Delta Hybrid D62S, D17L and AERsmart by means of sectional models. The team welcomed not only visitors from China, but also customers from Singapore, Malaysia and Thailand. Chuck Lim, Vice President Aerzen Asia Pacific, also participated in the IE Expo. First Environmental Protection Net conducted an interview with Sam Hoo, General Manager Aerzen China, on 3 May about the innovative AERZEN technology, and this was transmitted online.

The conclusion: the three trade fair days were very positive for AERZEN’s brand awareness and have confirmed the position of the company as a leader in the environmental market. Aerzen China is already looking forward to IE Expo 2019.

Determining savings potential online

With a right-sized machine configuration based on highly developed AERZEN technologies, the company offers maximum savings potential for all plant operators in waste water treatment. AERZEN customers can now easily test how efficient the aeration in their blower station really is with the performance calculator on the AERZEN website. All you have to do is enter your current number of machines, the volume flow and the differential pressure, and you will immediately receive an initial result as to the level of potential savings that can be achieved. You will also be shown what your individual machine configuration would look like with the technologies in question in order to achieve the savings potential.

Since each plant has individual requirements, AERZEN provides the customers with a tailored design based on the AERZEN Perfomance³ product portfolio - consisting of positive displacement blowers, turbo blowers and rotary lobe compressors.

Performance Calculator

Visit from IBAR to AERZEN

On 19th April 2018, a delegation from IBAR, the Upper Austrian sewage works operator association visited AERZEN. The guests were duly informed about the product range and visited the company offices. The visit to AERZEN took place following a suggestion from the Managing Director of AERZEN Austria, Martin Barger, who had made a special presentation at an IBAR meeting last winter. Martin Barger was also present at the head office in AERZEN, in order to welcome our guests, together with Markus Leidinger, applications specialist in wastewater technology.

At the start of their visit, Barger presented the history and product range of AERZEN to the sewage works operators. After this, Leidinger engaged with a compelling presentation about the application and combination possibilities of the different blower types. A factory tour was the next item on the programme. Product manager Ricardo Wehrbein and sales engineer Thomas Kuhn led the guests in groups through the company and presented each individual processing step for the blowers. Josef Ortner, Chairman of IBAR, thanked Barger and the management of AERZEN.

Remko Knol, the new CEO of Aerzen Nederland

On July 1st 2018, Remko Knol became the new Chief Executive Officer (CEO) of Aerzen Nederland B.V., based in Dui-ven near Arnhem. He is thus responsible for the business operations and strategy in the Netherlands. “We are very pleased that Remko Knol has joined our management team. He has a lot of process know-how and knows a lot about the development of production processes, as well as the application of AERZEN solutions,” says Siert Wiersema, Deputy Managing Director Aerzen Nederland.

Knol, who studied mechanical engineering and holds a master‘s degree in general management, can look back on 15 years of experience as a sales manager and managing director in the international technology environment. He has worked for Siemens Power Generation and Siemens Water Technologies, among others. For the past six years, Knol had served as Managing Director of Frames Separation Technologies B.V., Netherlands. The company designs and supplies process plants for the separation of oil, gas and water, as well as the treatment of production water.