How to improve the efficiency of your asphalt plant

In this article, N2P Design Engineer Peter Taylor explains several ways to improve the efficiency of your legacy asphalt plant, thereby reducing wastage and costs on diesel, gas and electricity – some involving automation and technology innovations, others not.

Tune your burners

The very first step to improving the efficiency of your asphalt plant is improving the efficiency of your burner, and the very first step to doing that is to tune your burner.

Why? Tuning your burner (calibrating and adjusting it) works exactly the same way as tuning your car – if it’s not properly tuned, you’re going to use a lot more fuel than you’d necessarily need.

How do you know if your burner isn’t tuned properly? Usually, you’ll get a lot of smoke coming out of your exhaust, similar to driving down the road behind a truck. If you’ve got the right amount of tuning, however, your plant will be burning nice and easy, and the smoke will be a lighter yellow colour.

Part of this is to maintain good oil pressure, and clean nozzles. This is a very simple maintenance step that should not be neglected. When you do this, the diesel is atomised very finely – which means it burns efficiently and easily. Exactly what we’re aiming for.

How An Asphalt Plant Works

To create asphalt, you put different-sized materials – anything from 40mm stone to a very find dust
or sand – and combine them with liquid bitumen within a drum.

Most of the raw ingredients get added into the drum by the slinger or cold feed, and a third of the way down the drum is where the bitumen pipe flows into the drum. To make perfect (or usable) asphalt, you want dust and heavy materials to get to the bitumen pipe at the same time. That way all the ingredients are coming together at the same time, in the right proportions – and your mix is in spec. Voila!

However, physics isn’t really on our side here, and dust and fine materials get blown through the drum very quickly, since they are so light … while heavy materials like 40mm stone take longer.

This is where time delays – otherwise known as “start and end delays” – become important, because they change time at which different materials are released into the drum, to ensure that they are coming together at the right time, to create the right mix.

 

Time Delays Minimise Wastage

Without time delays that control when each different material is released into the drum, you’ll end up with a whole lot of dust at the start of each run that’s contaminated and unable to be used again, and you’ll have wastage at the beginning and end of each run where your mix isn’t quite right yet.

What happens to that mix that isn’t quite right? Unfortunately, it usually it gets dumped. Some plants can recycle it, but most don’t, and it gets thrown in a rubbish pile somewhere.  Not only does that have an environmental impact, it has a significant financial impact too.

A tonne of asphalt is sold for $250 to $300, so if you’re losing 2 tonnes every single time you start a machine (that’s a minimal amount) – that’s $500 to $600 worth of waste. And that’s just when you start your machine ONCE or twice a day. Imagine if you start and restart your machine 10X a day (not unknown in the industry). That’s $25K to $30K of wastage in a single day. Ouch! With time delays, you can reduce that wastage significantly.

 

Training operators to do better estimations

In practice the perfect recipe isn’t always easy to achieve without automation or very accurate estimations.

However, if an operator is able to better what they’re doing, and why, then they are far better equipped to make changes and try and improve it; thereby minimising waste and improving your mix all-round. This is where targeted education and training come in.

At N2P Controls, we offer a half day on site training, customised to your business. This training will cover the following with approximate timings:

  • Feeder setup and operation – mechanical (1.5hrs)
  • How to improve their manual estimates (2hrs)
  • Plant operation, including typical safety interlocks (0.5hrs)
  • Plant walkaround (1hrs)

 

Automation of asphalt plant

More and more people are coming to realise the value of automating not just their mixers, but the entire plant.  Automation will ALWAYS be more efficient and accurate than manual operation and even the most educated guesswork.

With automated plant systems you’re going to produce a more consistent mix and less wastage and manage your mix more efficiently. Not only that, but you can test your mix at the touch of a button, leading to better quality control.

 

Our Solution- Introducing the MC404

Our MC404 control module is designed to ensure you make great mix, every time, and has great reporting features to allow you to drive efficiency from your plant.

All our control modules come with full documentation including, PLC code, functional descriptions, process flow diagrams, electrical wiring diagrams, commissioning sheets, and operational manuals so you can be sure your team will understand how to use the technology, removing the “guesswork” from the process. Better still, the reporting that this module provides demonstrates the both the efficiency and profitability gains within the plant.

If you are considering adding automation to your plant, so you can have less wastage and lower costs, a more reliable and consistent mix, and better quality-control, click here to contact us.

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