4 minute read
Plant optimisation for fertiliser manufacturers
Plant optimisation for fertiliser manufacturers
Paul Richardson, Service Center Manager at Sulzer’s Middlesbrough Service Center, looks at how revitalising existing rotating equipment can offer a cost-effective improvement in efficiency and reliability in the manufacturing process for fertilisers and other chemicals.
Advertisement
The equipment used to manufacture fertiliser in the chemical industry operates in a challenging environment, which can cause accelerated wear, reducing efficiency. The need to minimise capital expenditure means that replacement of machinery is not always a viable strategy. Rather than purchase new machinery, it can be more cost-effective to repair or modify existing plant equipment to extend its service life and make it more effective.
PROACTIVE MAINTENANCE
Generally, turbines, compressors and pumps are all subject to a variety of process-driven conditions that contribute to corrosion, erosion, fouling and various other processrelated issues and can be managed through effective maintenance intervention. Rotating equipment that is in direct contact with the process media and under constant attack presents a major challenge. It is possible, however, to reduce degradation to a minimum by selecting the correct protective coating.
In the harshest of operating conditions, solid and/or liquid particles can pass through the equipment causing erosion. This can result in moderate to severe material loss and change aerodynamic efficiencies significantly. If left unattended, it can even affect the critical components’ strength and lead to premature blade/vane wear and failure in service.
In situations where these circumstances exist, and their effect needs to be minimised, specialised coatings can improve protection against fouling and erosion. These can be applied to both stationary and rotating blades as well as diaphragms, guide vanes, rotors and impellers. The exact composition of these coatings can be tailored to specific applications and will include an aluminium base coat for corrosion protection as well as an inorganic sealer and a specialist non-stick final layer.
IMPROVING RELIABILITY
The most effective way of avoiding downtime caused by machinery breakdown is to employ preventative maintenance techniques, such as vibration monitoring, partial discharge analysis and thermal imaging. These procedures can be very useful in monitoring the overall condition of equipment and its remaining lifetime.
Analysing trends can reveal issues that would otherwise not be seen without disassembling the machine. Early indications of issues with bearings, coils, vane clearances or just general performance, allow remedial actions to be planned in during regular maintenance windows.
The advance warning also ensures that all the necessary personnel and parts can be assembled to ensure the most efficient use of time and any external resources that may be required.
REDUCING DOWNTIME
Shutdown periods provide an extended opportunity to carry out maintenance as well as refurbishment and upgrade work. As such, they allow companies to improve the performance and reliability of their equipment without affecting productivity.
However, with many legacy pieces of equipment used in the chemical manufacturing sector, some may no longer have support from the OEMs, which means that alternative solutions need to be found when repairs and upgrades are required. In other cases, OEMs’ lead-times may not meet the needs of the business, and an independent maintenance provider could be the best solution.
In situations where the speed of response is essential to minimise downtime, taking advantage of an experienced maintenance provider’s services and expertise could be the best solution.
CASE STUDY: RAPID REWIND
For example, a CO2 compressor powered by an ageing 1,300 kW high voltage motor had been identified for a complete rewind during a planned shutdown period. Sulzer identified the rewind option as the most cost-effective solution to extend the motor’s reliable service life without impacting productivity.
The project called for a complete rewind to be delivered within a 30-day window, which would require a fast turnaround. Since the OEM drawings were not available, the coils’ dimensions could not be established until the motor arrived in the service centre to be dismantled.
As part of the repair, the coil designers created the necessary drawings that would also deliver improved efficiency and performance for the refurbished motor. In cases such as this, where a motor has been in service for a few decades, the coil insulation will be of a lower specification than the materials used today.
Using class F insulation, which is thinner than the original materials, as well as improved processes, it is possible to increase the copper content of the coils to fill the gap that would otherwise be present. This additional copper also provides an incremental increase in efficiency and helps to reduce the operating temperature of the coils. By improving efficiency, the design modification also helps to reduce annual running costs.
In all, 60 coils were designed, manufactured and installed within the 30-day period. This was a complex operation, and the engineers worked through the night to complete the brazing, taping, varnishing and testing, before the motor was returned to the customer.
EXTENDING AND OPTIMISING LEGACY EQUIPMENT
Modern design and manufacturing techniques, as well as advanced alloys and specialised coatings, can all have a beneficial effect on the expected lifetime of legacy equipment. In situations where either the lead time or the scale of the expenditure for new equipment do not fit the business’ expectations, alternatives, such as retrofit projects, can deliver cost effective solutions within reduced timeframes.
The key to implementing the most effective solution is the experience and expertise of the solution provider. Turnkey projects are best delivered by those with all of the necessary skills and resources in house. For the end-user, a single point of contact that provides a full range of project options and continuous updates on progress ensures the management of any upgrade is efficient and cost-effective.
