SNoK AB Deploys Logix-Based PlantPAx Solution to Save Energy in HVAC

SNoK AB Deploys Solution to Save Energy in HVAC

Challenge

  • Development of non 'black box' solution that removes many of the issues faced by traditional HVAC solutions while saving up to 25% in energy costs

Solutions

Results

  • Up to 25% energy consumption reduction
  • Payback typically within two years
  • Less reliance on sensitive humidity sensors
  • Removal of pressure issues relating to ambient/external air mixtures
  • Control solution visible to operator – no need to employ specialist engineers

Background

 

SNoK AB, short for Skoglund, Nilsson och Kennedy, comprises a trio of experienced engineers and founding partners who offer a combined total of more than 70 years experience in industrial automation.

SNoK AB provides its customers with a structured approach to automation.

Rather than wait for a completed process design before taking the first steps in automation design, SNoK AB likes to adopt a different approach. Its experience in process, cooling systems, biogas production, HVAC and more, means that it can assist at a much earlier stage of the process system design.

Indeed, it is this earlier injection of SNoK's expertise that has lead it to develop a solution for the control of pharmaceutical HVAC, chiller/freezer systems and climate monitoring installations.

These solutions, which deploy Rockwell Automation hardware and software, not only save significant amounts of energy, but also offer far more precise control of critical environmental conditions.

These solutions, which deploy Rockwell Automation hardware and software, not only save significant amounts of energy, but also offer far more precise control of critical environmental conditions.

Challenge

With environmental control being so important in the pharmaceutical industry, HVAC systems often rely on 'tried and trusted' black-box-driven solutions that have been deployed the world over.

The problem is that these solutions utilise a very dated approach to environmental control – one that is not only difficult to regulate and control, but also particularly costly to run.

HVAC systems are large consumers of energy and provide controlled media to pharmaceutical applications.

Most HVAC systems are delivered with pre-configured control systems, which rarely provide energy efficient or application-specific performance.

"Control of temperature and humidity in a pharmaceutical plant is of paramount importance," explains Liam Kennedy co-founder and Manager of Control Systems at SNoK AB,"with many solutions involving energy-intensive cooling and re-heating. Many customers want to maximize their energy efficiency while also having access to the entire process and parameters, something that existing black box solutions simply do not allow to any satisfactory level."

In a typical HVAC solution for a pharmaceutical plant, when the external temperature is cold the plant draws air in and heats it; when it is warm, it draws air in, cools it and then reheats to remove the moisture.

As you can imagine this is an incredibly energy intensive process, however the industry likes this approach, as the air in and out is constant.

It is of course possible to reuse a portion of the air coming out of the plant and re-circulate it – something that would result in significantly less energy consumption – but pressure control is difficult and it is hard to maintain the positive-pressure differentials required by sterile manufacturing areas.

"Our solution allows them to do both," Kennedy explains. "We allow users to use the re-circulated air and combine it with the external supply while at the same time keep the pressure constant, thereby presenting no risk to manufacturing.

In a typical HVAC solution for a pharmaceutical plant, when the external temperature is cold the plant draws air in and heats it; when it is warm, it draws air in, cools it and then reheats to remove the moisture.

"The cheapest way to heat or cool a building is to reuse the air," he continues, "but you have to vary the amount you use due to the humidity, therefore a combination of outside and inside air must be used."

A traditional mainstream economizer will measure the outside air and will make a decision based on its humidity and temperature.

If it is too humid or too warm, it will put the plant on full recirculation. If it is cold or dry enough outside, it will let air come through and heat it up... using lots of energy.

The choice is full recirculation or full outside air.

"Another issue these traditional approaches face is that humidity sensors don't work well above 90% humidity," Kennedy tells us "This unreliability is what prompts the switchover from outside to re-circulated air. Operators have to use all or nothing because sensors are so unreliable."

Solution

"When we supply air we know that we need to supply a specific temperature and humidity, but we only look at the temperature of the outside air," Kennedy elaborates.

"If you know the return air humidity, you can work out the humidity of the outside air using basic air/temperature/humidity relationships.

This removes the reliance on unreliable external sensors.

"We control the system based on the humidity in the supply (air going into the plant) and return (from the plant) air only," he continues.

"By continually regulating the mix of return air with outside air we can create the right temperature and humidity requirements, reducing energy consumption and avoiding pressure drops.

Put simply, if the air entering the plant gets a bit damp, we will gradually take more and more air from the return or outside to get the conditions we want. Because we are using maximum return air – we are consuming far less energy."

At the heart of the solutions developed by SNoK AB, are Allen-Bradley ControlLogix and CompactLogix Programmable Automation Controllers (PAC) from Rockwell Automation.

At the heart of the solutions developed by SNoK AB, are Allen-Bradley ControlLogix and CompactLogix Programmable Automation Controllers (PAC) from Rockwell Automation.

The PACs are coupled to the rest of the system via Allen-Bradley Point I/O. Primary drive for the fan motors is delivered by Allen-Bradley PowerFlex 753 drives and local HMI is provided by Allen-Bradley PanelView Plus, and SCADA by FactoryTalk View SE, delivering an entirely visible control process based on PlantPAx control modules and faceplates for ease of programming.

The final part of the equation is the use of Stratix 8000 switches for interfacing with the process network. "I see an enormous benefit in the use of Stratix switches," Kennedy explains.

"In some jobs a lot of time can be wasted configuring Ethernet switches.

Automation solutions place demands on Ethernet networks that are 'not normal' and if the switch is not geared up to these demands then you have to 'play' with the protocols.

Stratix switches, on the other hand, allow you to define the type of connection (i.e. high-priority-traffic automation) and the switch will automatically dedicate the necessary bandwidth.

You simply configure the switch and just leave it – it's wonderful. I have never had any problems. I know that when I plug everything in, it will just work. The use of standard Ethernet cables also simplifies the whole business."

Results

The solution we have developed has the potential to save 20 to 25% saving in energy," Kennedy elaborates, "but the exact figure will depend on the environmental conditions.

However we are confident in predicting at least 15% savings over the year, and in a wet summer it could be as much as 25%. We are also confident that the system will pay for itself in less than two years."

The solution presents users with a number of key advantages, including the removal of the 'black box' approach.

"The entire HVAC control solution is exposed to the user," Kennedy explains. "We leveraged modules from the Rockwell Automation PlantPAx process control solution to develop the process control system.

We don't try to hide our solutions using closed technology, this is open... non black box, there is no hiding; the customer can see all of it. We will also share the code and standard modules.

Users can then go to any consultants or Rockwell Automation directly, who will support them if they decide to move to another supplier."

Other benefits of the system include a full and detailed alarm supervision solution which offers immediate identification of warning levels or failure, there are no vague summated alarms.

The system is also highly tunable to application-specific requirements and is ideal for GxP environments. SNoK AB also uses high-quality industrial controls and offers a worldwide 20-year spare parts guarantee.

SNoK AB has also developed a chiller/freezer system and a climate-monitoring solution for Pharmaceutical Storage.

All three solutions use common technology, which is entirely Rockwell Automation based and can be monitored using FactoryTalk Historian SE to provide access to trending and historical data upon which process decisions can be made and FactoryTalk VantagePoint EMI, which delivers this data to the user and displays it in easy-to-understand formats while providing the ability to dig even deeper.

Listen. Think. Solve., Allen-Bradley, ControlLogix, CompactLogix Point I/O, PowerFlex, FactoryTalk View SE, PanelView Plus, PlantPAx, FactoryTalk Historian SE and FactoryTalk
VantagePoint are trademarks of Rockwell Automation, Inc.
Trademarks not belonging to Rockwell Automation are property of their respective companies.

The results mentioned above are specific to SNoK AB’s use of Rockwell Automation products and services in conjunction with other products. Specific results may vary for other customers.

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