WATER & WASTE TREATMENT INDUSTRY FOCUS THE FIVE HIDDEN CAUSES OF CHP SHUTDOWN


James Thompson, managing director of Gen-C, explains how a live monitoring system can protect your CHP engine from the five most common hidden causes of engine shutdown…


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ombined heat and power (CHP) gas engines are one of the most expensive


pieces of equipment on an anaerobic digestion (AD) plant. They are also one of the most important, as a CHP engine unable to generate electricity means an immediate loss of income for the operator. Despite this, many AD operators in the water industry take a hands-off approach to maintaining their CHP; either relying on expensive locked-in service contracts that only cover mechanical issues or waiting for a problem to occur before taking action. Today’s latest CHP engines are finely


tuned, sophisticated pieces of kit that operate with precise tolerances. Correctly maintained, they will perform reliably for years to come; but leave them unchecked and you run the risk of underperformance, hard shutdowns and even catastrophic failure – all of which will reduce the volume of electricity being generated and, ultimately, an operator’s bottom line. Compare it to the airline industry: would


you trust an airline that only repairs its planes after they’ve broken? Or would you choose to fly with the carrier that constantly monitors its aircraft and takes pre-emptive action to protect its planes and passengers? Operators that can monitor their engine’s performance in real time, and review and compare data across a range of parameters, will be in the best position to prevent issues from happening. This is equally important for those with


an engine service contract. Despite costing thousands of pounds each month, such contracts only extend to the mechanical function of the engine itself. If an engine shutdown is attributed to an external factor, such as a gas issue, the contract is invalid. Not only will the operator then be forced to pay for the issue to be rectified by a third party, they can also find themselves being billed by their service provider for an out-of-warranty call out. To identify and correct issues before they


start affecting your engine’s performance, we recommend installing live engine monitoring. The IGS-LOG software, which comes as standard with the Motortech open access control panel favoured by today’s operators, enables water companies to understand what constitutes normal operation for their engine and spot any downward trends or anomalies before they affect its smooth operation. Giving operators full control over their engine, it


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gas pressure and noting any drops, water companies can better identify the cause of any unexpected shutdown and take preventative action to protect their CHP. 2. Gas quality Sewage feedstock is notoriously variable;


inputs can differ both regionally and seasonally, producing biogas of varying quality. Such changes will affect an engine’s performance, particularly if harmful contaminants such as H2S are allowed to build up. By monitoring the gas composition, operators can spot any corresponding trends in engine performance and alter their feedstock as necessary before their CHP becomes adversely affected.


James Thompson, managing director, Gen-C


The IGS-LOG live monitoring system tracks up to 25 key engine parameters


monitors up to 25 parameters, including the following five common hidden causes of engine shutdown. 1. Gas pressure Momentary drops in gas pressure, or


waning gas pressure over time, can result in a hard shutdown. Many operators become used to their engine cutting out as often as 10 or 12 times a day and simply restart it and carry on. But the long-term damage this causes to the engine can be irreparable. Potential causes of drops in gas pressure include flaring or a blockage in the gas line or filter. By monitoring the


Live engine monitoring enables water companies to understand what constitutes normal operation for their engine, and spot any downward trends or anomalies before they affect operation


3. Emissions Monitoring emissions is not just a case


of meeting the relevant criteria, it’s also a sure-fire way of determining the overall health of an AD plant and spotting any issues that have the potential to damage your CHP engine. The ComAp IGS-LOG provides 24/7 emission analysis, enabling an operator to fine-tune their engine. This allows water companies to see if their engine is running rich or lean – a rich engine will be running hot and wasting energy, while a lean engine runs the risk of misfiring – and take the necessary steps to address any issues before they present a serious risk. 4. Water pressure Another common cause of a hard engine


shutdown is a change in water pressure. While an operator would certainly notice the resulting interruption to their CHP’s performance, they would be unable to prove it was caused by water pressure and stop it from recurring unless the pressure was being monitored. Constant analysis of water pressure therefore helps to avoid the peaks and troughs that can result in performance issues and promotes smooth and reliable operation. 5. Kilovolts Finally, live kilovolt monitoring can


protect your CHP from long-term damage caused by ignition. An increase in kilovolts indicates a deterioration in spark plug performance, as the spark has to work harder to ‘jump’ the gap to create the initial spark. While it’s common for operators to gap and clean their spark plugs when they change the oil, this could be too late. An operator will often become used to hearing a tiny jump when their engine starts and dismiss it as a quirk of their engine, without realising that this noise is actually the sound of the engine misfiring. Live monitoring will highlight a rise in kilovolts or erratic KV readings, warning of a potential issue with the ignition system or spark plugs and prompting pre-emptive action to protect the CHP.


The Motortech open access control panel comes with the IGS-LOG as standard


GEN-C E: james.thompson@gen-c.co.uk www.gen-c.co.uk


PROCESS & CONTROL | SEPTEMBER 2020 27


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