How Blower Technology Can Help Meet The Ambitions Of The Circular Economy

Saverio Mattucci, Product and Markets Manager for Low Pressure Solutions at Robuschi, considers how to improve the total cost of ownership for blower technology in the wastewater treatment sector, in light of the wider move towards the circular economy.

The wastewater treatment industry and the principles of the circular economy go hand-in-hand. A key reason for transitioning to a circular economy is to help businesses reduce consumption of limited resources, to levels that can help offset increasing demand for these.

The move towards the circular economy means customers will be given far more information about the whole life costs and environmental impact of goods and services.

Therefore, for a wastewater treatment plant looking to implement the circular economy more holistically at a site, the ability to reduce the total cost of ownership of machinery and equipment should be a key concern.

Blowers are a key piece of equipment for aeration in the wastewater industry, which is a critical and energy-intensive process for this sector. Low-pressure blowers supply process air to aeration tanks, which are activated by the oxygen delivered as part of process air.

Mixing the sludge with oxygen increases its gas yield and reduces its retention time in the tank. If a site’s blowers cannot deliver the required air to the aeration tank, then the treatment process will fail.

Taking stock of costs

Aeration uses a considerable amount of energy, so it is crucial to match the type of blower specified to the size of the plant and its varying conditions, in order to deliver a good return on investment. Over-specifying is unnecessary and can be costly in the long run.

When traditionally investing in blower technology, operators have tended to be more concerned about the initial capital cost of a system. While this may be an important factor in the decision-making process, it should not be the sole one.

When investing in blower technology, operators should consider the upfront capital cost of the unit, the on-going energy costs, maintenance and servicing costs, and the cost of spare parts and repairs.

Taking control

While there are many control systems available for blower technology, it is generally recommended that a lower-pressure blower is connected to a programmable logic controller (PLC) system, which enables the blower to react to site demands, several times every single second.

Previously, if air demand slowed down at a site, then it could take two to three minutes for a blower to respond accordingly. Should this happen several times an hour, then a lot of potential energy is going to waste.

The latest PLC technology has been designed to react almost instantaneously, as site demands change. The quicker units are able to react, then the more money it is possible to save.

Under pressure

Eliminating downstream pressure losses is another key concern, which essentially comes down to regular and thorough maintenance. If a tank is losing pressure downstream, then the blower will be having to work harder to produce more process air – typically at a higher pressure to compensate for the pressure it is already losing.

Furthermore, as a blower will be operating at a low pressure to begin with, they cannot afford the inefficiencies that arise from downstream pressure loss. This might be due to a broken pipe or damaged diffuser, but whatever the reason may be, a comprehensive maintenance strategy will help ensure this risk is managed.

A genuine opportunity

It is also critical to consider the spare parts that will be used for a blower system. Non-genuine spare parts are typically cheaper than a manufacturer’s original parts and, when trying to cut back on costs, it can often be tempting to opt for these.

Nevertheless, it is widely accepted that using non-genuine parts can be detrimental to a blower’s overall performance and can have a negative impact on a machine’s efficiency and energy consumption.

In some cases, the wrong spare part can cause real damage. This can potentially result in the system failing completely. The outcome? Not only an expensive repair bill, but costly unexpected downtime too.

In addition, by replacing these with a non-genuine alternative, there can be no guarantee that the manufacturer’s warranty will be upheld.

In contrast, genuine parts will have been manufactured to meet the same standards as the blower that they are intended for. So, they will have passed the manufacturer’s stringent testing regimes, in a quality-controlled environment, to ensure a system continues to operate reliably.

Real-world results

One site that is working towards the ambitions of the circular economy is the Kinnegar wastewater treatment plant in Belfast. Operated by Charles Brand, a leading provider of tailored water and wastewater solutions, the site requires blowers to aerate its sequencing batch reactors and treat wastewater.

The company previously used five 132 kW oversized blowers for the aeration process. These units were 16 years old and required increased maintenance to keep them in good working order. Faced with escalating costs, Charles Brand identified that savings could be made by upgrading its aeration system using advances in blower technology.

The solution was to replace three of the 132 kW units with 75 kW Robuschi Robox Energy screw blowers, which offered a payback period of three years.

The Robuschi Robox Energy screw blower combines a screw compressor with a permanent magnet motor, allowing for pressure up to 1000 mbar(g) and capacity up to 2,600m³/h.

Its internal compressor, combined with an efficient permanent magnet motor, is directly fitted to the conductor shaft to prevent loss of power from the belt drive.

Charles Brand is also able to monitor the operation of the entire unit via an intelligent HMI control panel. This can be remotely connected, meaning performance can be monitored anytime, anywhere, and help inform predictive maintenance.

The screw blower requires 30% less space than comparable units and comes complete with an integrated variable frequency drive (VFD). The units were installed in simple ‘plug-and-play’ fashion – operators only needed to connect the piping, electrical power line and control panel to the system.

The result? The new blowers are capable of achieving cost savings of up to approximately £5,000 a year, making them ideal for the energy-intensive wastewater treatment sector.

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