Industry insight: Five smart ways to increase engine efficiency on AD plants

The UK’s anaerobic digestion industry has experienced rapid growth over the past 10 years, with a total of 648 plants now in operation.

Despite the recent increase in biomethane facilities, most of the biogas produced from anaerobic digestion (AD) is used to generate electricity and heat, making the combined heat and power (CHP) engines that convert biogas into usable energy a vital piece of equipment.

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But with many of these engines now at least five years old, what is the impact when they fail or underperform? And is there any alternative to either costly engine replacements or expensive service contracts?

Here are my five smart upgrades that can transform any gas engine into a more efficient and profitable piece of kit.

Install an open-access control panel

Many service providers use a ‘closed’ control panel as a means to coerce the owner into a restrictive service contract. This means that you are potentially looking at your engine being down for days whenever there’s a problem while you wait for the service provider to despatch an engineer to your site ” often at an additional cost to you.

By upgrading to an intelligent, open access control panel, an operator can remotely take control of their own engine via their laptop, phone or tablet; instantly assess how their engine is performing; control their engine’s running parameters, adjusting them to match the biogas composition; and restart their engine themselves within seconds ” without even needing to be on site.

Fit a flexible fuel mixer

If an engine runs too lean it can backfire, resulting in exhaust damage, vibrations and instability, and causing parts to wear out more quickly. If it runs too rich, then too much fuel will be used, the engine can overheat, and there is a risk of parts burning out.

A flexible and fast-acting mixer enables an engine to handle variations in gas volumes and composition.

This is especially important for biogas plants treating food waste, as this is a constantly changing product. These air/gas mixers comprise a range of flow bodies to suit every feedstock type, based on a plant’s individual gas composition. If the composition alters significantly, the flow body can be changed as required, ensuring the perfect fuel mix every time.

Use an ignition controller with pulse technology

If your engine shudders during the ignition phase, replacing the controller with one using pulse technology will deliver more reliable ignition and prolong the life of your equipment.

This creates thousands of tiny pulses, the intensity and duration of which can be programmed according to the plant’s demands, and which will remain the same throughout the lifetime of the ignition controller.

Switch to a smart knocking control system

A ‘knocking’ sound usually signals that the gas is igniting too early. A sophisticated, intelligent knocking control system can detect this and automatically alter the ignition timing point. If knocking still occurs, it will then reduce the load of the engine or even shut it down, preventing catastrophic engine failure.

Specify a high-temperature speed control

The throttle actuator responsible for speed control is usually located close to the intercooler ” a part of the engine which is particularly hot. Proximity to a heat source can cause this component to deteriorate more rapidly, often leading to poor performance or failure. To counteract this, look to utilise specialist high-temperature throttle actuators, which help to prolong operational life. They also comprise an integrated throttle body which contains fewer moving parts by being directly connected to the throttle. Not only does this make for more accurate control of speed, it also incurs less wear and tear.

Take pre-emptive action. Every day that an AD plant isn’t generating electricity is a day it’s losing money, so don’t wait for your engine to fail before taking action. By scheduling an engine upgrade to coincide with any planned maintenance shutdown, operators can benefit from increased engine availability, more reliable performance, longer-lasting components and greater electrical output.

About the author

James Thompson is managing director of independent CHP parts and service provider Gen-C.

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