Price versus TCO? A long-term cost analysis model for the wastewater treatment industry

With the average lifecycle of a Water treatment plant counted in decades, it is important to take considerations when selecting blower equipment to perform cost-efficiently throughout its service life.

All too often, the selection process focuses on the initial price tag, with less importance placed on the ongoing operating and maintenance costs.

Some studies suggest that the initial price can represent less that 10 per cent of the total lifetime costs for industrial equipment, with energy costs and maintenance representing at least five times more than the upfront costs. When considering new capital investment, it is important to be able to compare and evaluate all facets of the equipment or system proposed against any other solutions being considered to reach a true conclusion on overall ownership costs.

Total cost of ownership – at a glance

The aim of TCO is to place a single value on the complete lifecycle of a capital purchase. In the wastewater industry, this must take into account every phase of ownership, from the initial purchase tag, to the on-going energy costs, maintenance, repair and servicing costs.

Why this is so important for water treatment?

The energy used for aeration in a wastewater treatment plant typically accounts for between 50-60 per cent of the site’s total energy consumption and in some instances, can be as high as 70 per cent.

Low-pressure blowers supply process air to aeration tanks, which are activated by the oxygen delivered as part of process air.

So, blowers are a key piece of equipment for aeration in the wastewater industry, which is a critical and energy-intensive process for this sector.

It is crucial to investigate some of the considerations when selecting blower equipment to perform cost-efficiently throughout its service life.

What are the factors that contribute to best-in-class TCO

??Purchase cost – The initial cost.

??Operating costs including the cost of installation and commissioning and the energy required to power the equipment.

??Maintenance and service – The cost of routine preventative or predictive maintenance, alongside reactive emergency repairs, and the cost of genuine spare parts - The cost of downtime

??Equipment longevity affecting its renewal time.

What are three key factors to take into account before choosing a blower equipment investment?

Step 1 - Capital investment cost

When purchasing a new blower, the technology chosen must be based on the precise application demands and operating parameters.

Before focusing on the technology, the following areas should be considered as part of the specification process, to ensure the type of blower has been sized correctly to suit the plant and its varying conditions:

? Minimum and maximum air pressures

? The compressed air flow required by the system

? The blower’s overall energy consumption

Capital investment should also take into account any costs for designing, installing and commissioning the system, including any electrical or mechanical infrastructure set up requirements.

Step 2 - Operating costs for energy-savings

It is essential to minimise energy consumption as much as possible.

In order to achieve an energy-efficient solution, you need to consider:

??The speed regulation, with the use of variable speed drives and invertors, as well as sophisticated control systems, to match air flow to plant demand. With process demands for air fluctuating constantly in aeration application a blower’s ability to increase and decrease air flow rates is vital.

??The possibility to minimize pressure drops, as this can affect operating pressure.

Step 3 - Maintenance costs for having Lifetime system performance

The final piece of the TCO equation is the cost of servicing and maintaining the installation.

Some key considerations to help minimize these costs are:

??Invest in machinery that is, by its design low maintenance or can be serviced easily

??Choose genuine spare parts and lubricants for ensuring that performance is not compromised.

??Consider oil-free options.

??Manage pipework leaks, which can contribute to as much as 20 to 30 per cent in wasted energy.

??Follow the manufacturer’s required maintenance schedule

Which aeration technologies should be chosen according to these key factors?

There is a wide choice of blower technologies on the market. With numerous types of blower technology available, this needs careful consideration.

For the wastewater treatment and especially for the biological aeration process, Robuschi is a leading supplier of:

??Positive displacement rotary lobe blowers,

??Screw blowers,

??Turbo blowers, with centrifugal compression.

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With these technologies in its product portfolio and many years of experience, Robuschi is able to make a technology comparison taking into account all key success factors for this application.

The TCO result between these three different technologies can be summarized in this diagram:

Regarding Capital investment, the latest, dynamic high-speed turbo blowers with centrifugal compression are typically the most expensive blower option, but with this bigger price tag comes higher levels of efficiency. A pressure rise is achieved by adding kinetic energy to a continuous flow of air through the rotor or impeller, for superior energy performance. A high-speed motor coupled directly to the impeller means that there is also no gearbox and therefore no mechanical friction losses for improved efficiency.

Regarding operating costs, Turbo blowers feature a high-speed motor and drive to reach high rotational speeds, with the advantage of a variable frequency drive to adjust speed easily. The impeller uses air foil bearings, which generate a completely contactless transmission when the turbo blower is running. This eliminates any mechanical efficiency losses, as well as ensuring no oil is needed in the system’s air end, all contributing to high energy and environmental performance.

Regarding maintenance, Turbo centrifugal blowers are well suited to medium or large air flows at a wastewater treatment part.

With no oil and the contactless transmission, maintenance demands are reduced significantly – also contributing to excellent longevity.

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Convinced? And for you? Which technology seems to be the most suitable for aeration in water treatment plants? Hurry up, contact our sales representatives! https://ow.ly/qASa50NXoEq