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Case Studies

HRSG Trouble Shoot Long Time Waveform Data

At the request of the Station Engineering Manager we were requested to come up with a way of recording vibration from the lower portion of the Gas Turbine Boiler HRSG expansion manifold. The HRSG’s are exhibiting vibration at all times whilst in operation however the amplitude of vibration appeared to be noticeably higher when the unit load reduces to 600MW or below.
A number of different methods were suggested but the simplest and cheapest way of getting some results in the short term was to use the site’s own vibration data collector. The Commtest vb7 has an advanced data collection feature called ‘Long Time Waveform’ which essentially collects a continuous stream of vibration data over a pre determined time frame or can be stopped according to user preference. These vibration streams can also be configured to look over a wide range of specified frequencies and can be converted to three unit preferences for displacement, velocity or acceleration.
As the vibration inherent in this system was expected to be very low frequency the collection parameter defined was a 0-50Hz displacement reading. The changes in unit load were expected to occur overnight so the vb7 was left collecting data from 15:05 on 3rd August and was manually stopped at around 08:15 on 4th August on HRSG 11.
The data obtained during this time is shown on the summary screen shot below. 

vb7 Screen Capture








As can be seen two periods of increased vibration were noted, the second being 2hrs 6mins into the run highlighted with the cursor. These increases did tie into unit load changes during the night.

The data was downloaded into the software for further analysis. Detailed examination of the data is shown below.

Long Time Waveform #1
Long Time Waveform #2

Plot No.1 & 2.

Shows an example of the amplitude of vibration under constant high load conditions which from this data appears to be consistent. As can be seen the peak to peak amplitudes are around 4.3mm. The lower part of this graph shows a partial FFT (Fast Fourier Transform to frequency) of the time data highlighted by the green box. The normal oscillation of the HRSG is shown to be 6.1Hz. The plot below shows a zoomed in version of the above graph. As can be seen from this graph the frequency remains consistent but the amplitude is inconsistent, this is due to the resonant response of the structure. 

Thermal Imaging In The Food Industry

In the food industry, it is essential to carefully control the temperature of perishable goods throughout production, transportation, storage and sales.

Repeated warnings about illnesses due to tainted and improperly cooked foods highlight the need for tighter process control. Because this almost always involves a human factor, food processors need tools that automate crucial operations in a way that helps minimise human error while holding down costs.

Thermal imaging cameras are such a tool. Analogue video outputs can be viewed on video monitors, and digital temperature data, including MPEG4 video outputs, can be routed to a computer via Ethernet.

The main elements doing non-contact temperature measurements in the food processing industry are a thermal imaging camera and associated software.

They act as “smart” non-contact sensors to perform 100% inspections, measuring the temperature of equipment, refrigerated products, and cooked foods as they exit the cooking process.

Thermal imaging cameras are easy to use, small, and can be positioned almost anywhere as needed. They can also be used to inspect package sealing, and improve efficiency in other food processing operations.

An IR temperature measurement and thermographic image are used to locate undercooked chicken tenders and stop the line so undercooked ones can be removed.

Pictured alongside: An IR temperature measurement and thermographic image are used to locate undercooked chicken tenders and stop the line so undercooked ones can be removed.

FLIR thermal imaging cameras have firmware and communication interfaces that enable their use in automated process control.

Third-party software makes it easy to incorporate these tools into automated machine vision systems without the need for extensive custom-written control code.

The use of thermal imaging cameras in food processing is growing for applications such as:
- Oven baked goods
- Microwave cooked meats
- Microwave drying of parboiled rice and other grains
- Inspecting ovens for proper temperature
- Proper filling of frozen meal package compartments
- Checking integrity of cellophane seals over microwave meals
- Inspecting box flap glue of overwrap cartons
- Monitoring refrigerator and freezer compartments

Thermography for quality assistance and product safety

Thermal imaging is first and foremost a quality assurance (QA) tool. Controlling the quality and safety of cooked meat products is an excellent use of this technology.

A permanently mounted thermal imaging camera can record the temperature of, for example, chicken tenders as they exit a continuous conveyor oven.

The objective is to make sure they are done enough but not over-cooked and dried out. Reduced moisture content also represents yield loss on a weight basis.

Thermal imaging cameras can also be used for inspection on microwave precooking lines. Besides improving product quality and safety, overall throughput can be increased. An additional benefit is reduced energy costs.

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vbOnline™ condition monitoring system set to challenge market

Everyone agrees that remote access to predictive maintenance systems can conveniently increase plant machinery uptime, and increase overall businesses profitability. So why then are only 37% of condition-based monitoring systems connected online?
With ever tightening manufacturing processes and costly time-based maintenance programs, ensuring the functional reliability of critical plant and equipment is a considerable responsibility.
Used as part of a predictive maintenance program, online condition-based monitoring systems can provide increased convenience, and help reduce lost production and overall cost of maintenance.
Until now the required investment for these systems has been out of the reach of many. This is about to change with the launch of Commtest's new vbOnline™ system.

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Metso Logo
Metso Case Study
Metso Minerals, based in Matamata New Zealand, designs and manufactures up to 23 tonne Barmac (Vertical Shaft Impacter) VSI crushers that can pulverise between 10 and 2080 tonnes of rocks per hour into bite-sized smithereens.
With such formidable force the slightest structural imbalance can cause almost as much damage to the machine itself, as it does to the rocks it punishes. While maintenance is critical and repairs are inevitable, Metso design engineers are discovering the advantage of using Commtest VB 2000 to fine-tune prototypes and minimise wear and tear on machinery. In just three years since they incorporated the Commtest vibration analyser system into their test programme, Metso Minerals have more than justified their investment. They have been able to achieve, and pass onto their customers, significant product design enhancements that increase performance and reliability, and reduce costs all round.

Rock On Rock For Crushing Results
Invented in New Zealand the Barmac VSI is globally unique due to its power-saving crushing process. Unlike other types of crusher, which use metallic parts to crush rocks, the Barmac uses rocks fed into the machine to crush others through high velocity impact. Rocks entering the rotating rotor are hurled at high speeds into the chamber and smashed against other rocks falling through the machine. Adjusting the rotor speed controls the size and shape of the reduced product desired for the application.

The Barmac has found a home in many niche applications offering lower power consumption, up to 50% less wear and tear to metal parts, and increased product throughput by up to 30% over other technology.

The machines are used in over 3000 quarrying and mineral processing sites worldwide. Customers include aggregate and sand processing plants, industrial mineral sites from cement clinker to diamond mines, to waste and recycling sites.

In such critical and dangerous environments reliability and productivity is key, and customers can ill afford to have any component of their business out of operation and in need of costly repair. Therefore, a constant challenge for Metso design engineers is building a crusher that can withstand the rock-pounding abuse, is easy to maintain, cost-effective to produce and operate, and requires minimal downtime.

Using Vibration Analysis To Avoid Resonance Damage
The design of Metso machines has advanced considerably over the years and they are now used in more applications and run at a wider range of speeds than ever before.

"We used to employ consultants to perform vibration tests on new prototypes as well as on problematic machines. But this was proving a costly exercise and didn't allow the flexibility or convenience of experimenting with and analysing a variety of tests for detailed design and modification," said David Kenny, R&D Engineer at Metso Minerals.

"We started doing our own tests three years ago after an incident where we were baffled as to what had caused a cracked shaft on one of our machines. We were amazed when a consultant established the fault straightaway using Commtest's vibration analysis equipment in a bump test. He found that, at a certain speed, the resonance - or natural frequency - of the machine was the root cause of the problem. The solution was to adjust the rotor speed above or below its natural frequency, and we had no more problems."

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vbOnline™ Integrated with Bently Nevada Condition Monitoring System in ambitious project

Commtest's permanent condition monitoring vbOnline® system has been successfully integrated with a Bently NevadaTM 3500 system in a recent collaborative project.vbOnline

Enersur-Suez Energy Peru is a 130MW hydroelectric plant. As the largest energy provider in Peru, Enersur also provides a substantial amount of energy to neighboring Brazil. The company wanted to add vibration analysis of their hydro generators to their protection system. Installing a permanent online system would ensure scheduled readings were regularly monitored and analyzed.

The machinery being monitored is among some of the most remote in the world, located high up in the Andes mountain range near the edge of the jungle district. After flying into Lima, Commtest's Customer Success Engineer Shane Smith and local channel partner Marco Ortiz drove 300km up the steep and often winding road. "Altitude sickness was a problem," says Smith "but the mountains were incredible". The facility's inherent lack of accessibility was a key driver in the decision to install a system that could remotely monitor Ensersur's machinery and transmit the data off-site.

Two 32 channel vbOnline systems were set up to take 39 readings from buffered outputs of a Bently Nevada 3500 rack. These signals correspond to 18 radial proximity probes, 6 axial probes, 3 keyphasor® and 12 airgap sensors. All sensors were pre-installed in three hydro generators of 44.5MW each.

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Must Read Guidebooks

Booklet: Thermal imaging guidebook for industrial applications

Numerous industries worldwide have discovered the advantage of incorporating infrared cameras in their industrial processes and programs. This booklet is an in-depth guide for these industrial applications.

Booklet: Thermal imaging guidebook for building applications

Thermal imaging cameras are powerful and non invasive tools for monitoring and diagnosing the condition of buildings. Energy losses, missing insulations, air leaks, moisture and many other building related problems become immediately and clearly visible on a thermal image.

Booklet: Thermal imaging guidebook for automation applications

Automated IR (infrared) radiation imaging offers the potential for improving a host of industrial production applications, including process monitoring and control, quality assurance, asset management, and machine condition monitoring.

Booklet: Thermal imaging guidebook for gas detection applications

Infrared cameras can also play a major role in helping to decrease environmental damage. They are successfully used for detecting insufficient insulation in buildings, identified as one of the highest opportunity areas for decreasing the greenhouse effect, as well as detecting environmentally dangerous gas leaks.

Booklet: Thermal imaging guidebook for R&D Professionals

Although infrared radiation (IR) is not detectable by the human eye, an IR camera can convert it to a visual image that depicts thermal variations across an object or scene.


Proviso Systems Ltd provide condition monitoring and predictive maintenance solutions to the UK market.

Contact us today to discover more about how we can help you improve your asset reliability and availability.

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