Thursday, July 5, 2012

Container Shipping to LNG Bulk Carriers - Everyone Needs to be Pumped Up

Old Maintenance Techniques Cost Money Says Colfax
Shipping News Feature

WORLDWIDE – When it comes to vessel maintenance the phrase ‘if it ain’t broke don’t fix it’ was long the watchword for engineers everywhere but now one company at least is trying to change attitudes to one of the vital components which every decent sized ship, from container vessel to LNG bulk carrier, needs to continue a voyage uninterrupted. With a view to upgrade the efficiency of those everyday but essential items, fluid pumps, such as those used for ballast water and cooling in the ocean shipping sector, Colfax Fluid Handling has come up with a concept they call Allmind.

As the name suggests the concept, developed from a single leakage control device, has become an intelligent condition monitoring and variable speed control unit which will protect a pump, maximise its efficiency, lower energy usage and reduce maintenance and spare parts costs. The condition monitoring module has the ability to maximise system availability by providing component-specific information. This measurement of the health of a pump by routine monitoring and analysis of data helps avoid unplanned downtime.

Colfax says that despite the best intentions of shore-side superintendents, under constant pressure to reduce operational expenses and equipment downtime, the best pump systems are at risk due to a lack of diagnostic information and sophisticated control systems. The shortage of experienced crew and out-dated attitudes to pump operation undermine management attempts further, and the result is needlessly high operation and maintenance costs, increased downtime and frustration for all involved.

Colfax calculates that energy costs account for 85% of the total cost of ownership for ballast and cooling pumps, which they say demonstrates the importance of assessing total cost of ownership rather than basing purchasing decisions purely on initial cost. This means that upgrading should take this factor into account and, says Colfax, this necessitates keeping abreast of technology and, as is often the case with pumps, recognising when old practices must make way for the new to achieve greater operational efficiency and profitability. Christian Martin, Director, Product Management Commercial Marine at Colfax, says:

“Allmind is a modular system using the right number of sensors to monitor the critical characteristics of each specific pump. If a ship’s system or processes change, you can easily modify or expand the modules as needed. This modular approach is also ideal for retrofitting of existing systems. We have the technology to reduce the energy consumed in pumping operations by up to 50 per cent simply by enabling variable speed operation. Add intelligent diagnostics and reliability goes up and maintenance costs go down – dramatically.”

Allmind is designed to detect early phases of damage to mechanical seals through continuous leakage monitoring and its vibration analysis module monitors mechanical oscillations and continuously compares them to threshold values, thus detecting imbalance and thwarting any operational damage. The vibration analysis module also monitors bearing condition. Allmind analyzes oscillation changes and signals bearing wear at a very early stage and is capable of detecting unusual levels of motor load. Traditionally, fixed speed operation using throttle valves has been the norm for pump operation for most ships. As process demands change, the control valves are used to regulate process parameters. However, this practice changes the frictional losses in the system and as a result changes the system performance curve. Rather than the pump being controlled to adapt to changing conditions, the system is being adjusted to achieve the required process demand.

This type of process control can often lead to pumps being operated at flows outside of the operational limits (part load or overload) resulting in poor asset reliability, unsafe operating conditions and higher energy and maintenance costs due to unnecessary high hydraulic loads and high impact to bearings.

Traditionally most vessel borne machinery is designed at speeds and levels to comply with worst-case scenarios. This results in larger dimensioned systems and increased energy consumption of which in most cases, is unnecessary. For example, a ship’s cooling system when operating in the Caribbean, must perform sufficiently to meet the maximum cooling demand of high fresh water temperatures caused by multiple pieces of machinery operating concurrently. Full speed operation of pumps and coolers are necessary at this time. But such a situation depending on ship location seldom, if ever, occurs.

Now with slower steaming often the vogue, plus a hardening of attitudes toward high maintenance costs in a time of austerity, Colfax says there are substantial potential savings for ships that were designed for high speed, such as container ships previously sailing between 24 – 28 knots. Mr Martin continues:

“The majority of a pump’s lifetime and vessel requirements are much lower than the system design point. Reducing pump motor speed grants major cost saving advantages. In the days when sailing speed was a priority, system components were sized accordingly. Today, many of these vessels (main engines) operate on much lower and more energy efficient speeds, but the cooling water pumps may still run at full speed. Allmind keeps all pumps running at optimal speeds and loads, thus minimizing total energy use."