Four practical steps to improved sustainability

Industrial sustainability Insights

• The concept of sustainability has changed from profitability toward reducing climate change’s effects as well as becoming energy efficiency. Even so monetary benefits include $16,000 savings per steam trap failure avoided (up to 18% of steam traps fail in a large chemical manufacturing facility per year); LED fixtures save up to 70% in energy, not counting ability to turn off automatically.
• Digital transformation can provide critical tools to develop related key performance indicators (KPIs) to track sustainability programs’ effectiveness.
• Wireless technologies can provide operators more freedom to handle the tasks they need away from the plant floor in some cases. Wireless networks can reduce costs 70% or more.

It was once thought a company was sustainable if it had the capital and resources to continue in business over the long haul and even grow. Now, the meaning of sustainability has expanded to ask if a company’s activities are minimizing the effects of climate change and responsibly using resources. Naturally, the earlier factors still apply, but profitability alone is not as sufficient.  

High on the problem list is unrestrained use of fossil fuels and associated emissions, primarily due to climate change concerns. Other issues extend into a variety of areas, such as excess emissions, poor energy efficiency, and overuse of water and other scarce resources. Companies wanting to make changes often end up confused, trying to understand what is being demanded by stakeholders. How does a facility put “reduce carbon footprint” into practice? How can it measure success, or lack of it? 

Sustainability efforts also deliver bottom-line benefits, such as $16,000 savings per steam trap failure avoided in a large chemical plant, and 70% savings in lighting, among others. 

Four industrial sustainability areas of focus 

Some companies may explore a major process change to move away from hydrocarbon feedstocks, but for now companies should concentrate on improvements in four common areas: 

1. Reducing wasted energy use by steam traps. 
2. Monitoring and reducing emissions from pressure relief valves (PRVs). 
3. Monitoring efficiency and reducing energy use by heat exchangers. 
4. Reducing energy use from facility lighting. 

Improvements in these areas reduce operating costs, while contributing to sustainability programs by: 

• Reducing process waste. 
• Improving process efficiency. 
• Reducing energy consumption and resulting greenhouse gas emissions. 
• Reducing water and air contamination. 
• Improving maintenance efficiency for lower costs and improved equipment availability. 

Sustainability through digital transformation

Running in parallel to sustainability is digital transformation, the strategy of integrating digital capabilities to improve performance. Digital transformation does not improve sustainability by itself, but it provides critical tools to develop related KPIs to track the effectiveness of sustainability programs.  

The first step toward sustainability is determining where the largest improvements can be made. Unfortunately, finding those areas often calls for measurements not used for process control or monitoring. Implementations must start by deploying new sensors to monitor variables related to energy consumption, asset condition, and other factors. This can be problematic because the costs of cabling and system integration often outweighs the cost of sensors. 

Digital transformation technologies change the picture entirely. It is necessary to install sensors on physical assets, but each can communicate via WirelessHART to a host system, so no cables need be installed, dramatically reducing installation costs and time. WirelessHART networks integrate seamlessly with a facility’s larger Wi-Fi and Ethernet networks (Figure 1), so sending data to host systems, such as an asset management system, is simpler and more efficient. 

Figure 1: The ability to deploy WirelessHART devices makes monitoring systems much easier to deploy. Courtesy: Emerson

Preconfigured data analysis tools can collect raw sensor data, process it, and present it to the reliability and maintenance teams via interactive dashboards. This operations technology information also integrates with IT systems, the cloud, and corporate networks. Configuration requirements are minimal, and in most cases, no system integration assistance is necessary. This approach is a basic building block of sustainability programs, and a key technical element. 

Eliminating cabling infrastructure saves enormous volumes of copper, aluminum, steel, plastics and other materials produced from oil feedstocks and mined metals. Considering all the labor for design, transport, installation, and maintenance avoided, WirelessHART networks reduce costs by 70% and more compared to traditional techniques. 

The types of sustainability projects described below reduce energy consumption, improve efficiency, reduce emissions, and/or reduce process waste, often delivering multiple benefits simultaneously. Some projects extend equipment life through more effective maintenance, which also improves safety and reduces environmental and other incidents. 

1. Steam traps—wasted energy

Once steam has done its work, it condenses back into water. A steam trap separates drains the liquid condensate from live steam lines, and this decreases overall energy efficiency, but is needed to protect equipment.  

A steam trap is a valve that opens and closes automatically to release condensate. All designs therefore have some moving parts and a seating surface. Unfortunately, scale in the lines can break free and come to rest in problematic spots, such as valve seats or mechanisms. Traditionally, annual audits are conducted on steam trap systems and generally classify trap condition by diagnosis: 

• Visible steam leak: Major mechanical failure directly wasting steam 
• Blow-through: Continuously releasing steam directly into the drain, wasting steam 
• Cold: Stuck closed with no condensate release, resulting in a back-up of condensate that reduces steam quality and can cause damaging water hammer events 
• Working: Effectively removing condensate.

A recent study suggests 18% of steam traps in a large chemical manufacturing facility fail each year, resulting in wasted energy costs of up to $16,000 per failed trap. Given that steam is a significant energy budget item for most plants, reducing this waste can be a quick win for sustainability programs. 

Most steam traps do not release condensate continuously. Under normal conditions and if sized correctly, steam traps open intermittently and discharge condensate in slugs. This action transmits noise through the adjacent piping. An acoustic transmitter mounted nearby (Figure 2) hears the cycling, and an algorithm learns its characteristic activity. Each device sends data via WirelessHART to a central analysis platform, where operators monitor how all steam traps equipped with acoustic transmitters are performing. 

Figure 2: Emerson’s Rosemount 708 Wireless Acoustic Transmitter provides visibility into steam trap operation and condition by analyzing ultrasonic noise signatures. Courtesy: Emerson

Dashboards indicate which steam traps are working correctly, and which are in a failure mode. The software estimates lost energy and resulting costs at any time. Maintenance personnel see which steam traps need attention and plan accordingly.  

2. Pressure relief valves—process loss

Pressurized systems must have a mechanism to let internal pressure escape before it becomes a dangerous condition, typically a PRV. Monitoring the condition and activity of PRVs should be a part of normal plant operation, but there are no mechanisms within a typical PRV capable of sending information to an automation system.  

Monitoring a PRV borrows from traditional maintenance techniques: listening. An acoustic monitoring device, the same as used with steam traps, mounts directly on a pipe adjacent to a PRV. It captures ultrasonic frequency sounds made by the fluid passing through the valve seat, which is transmitted through the metal.  

When a PRV opens, releasing liquid, gas, or a mixture of both, the acoustic monitor reports any resulting noise to the automation system. Once system pressure is relieved, the valve should close and seal itself again, and the noise will cease. Data from the acoustic monitor reports the time the discharge began and ended via a graphic dashboard (Figure 3), while giving some indication of how serious the discharge was based on noise amplitude. 

Figure 2: Emerson’s Rosemount 708 Wireless Acoustic Transmitter provides visibility into steam trap operation and condition by analyzing ultrasonic noise signatures. Courtesy: Emerson

Without PRV monitoring, operators are not aware of a release unless and until they notice increased flow to flares or relief systems. Their first response is to determine where the source is using knowledge and experience with the process, for example by looking at where the process is at higher pressures. When PRVs are monitored, operators can reduce response times because the sensors direct the operators to where the event has occurred. This contributes to reducing the duration, number and amount of emissions, one of the key goals of sustainability programs. 

One common problem is incomplete resealing. If the seat is damaged or particulates lodge in the valve, it may not close completely, leaving it perpetually “simmering,” releasing product to the unit’s pollution control systems, or in the worst case directly to the atmosphere. When this happens, it may take hours or days for operators to realize there is a problem, and then pinpoint where it is happening in a complex system. An acoustic monitor hears the simmering, even if it is very minor, eliminating maintenance guesswork and facilitating more effective repair efforts. 

3. Heat exchangers—inefficient energy use

The transfer capacity of any heat exchanger gets degraded by a universal problem: fouling. Particulates carried by the fluid streams deposit on internal surfaces, and heat conductivity declines in proportion to the deposit type and thickness. Fouling from either side of the exchanger, and potentially both, reduces heat transfer rates, and therefore efficiency. Determining efficiency depends on measuring a list of critical variables:  

• Process fluid temperature differential (inlet compared with outlet) and flow 
• Transfer fluid temperature differential and flow (for liquid-to-liquid designs) 
• Cooling air temperature and flow (for air-cooled designs). 

With these measurements, it is possible to determine how much heat is being transferred, and therefore overall efficiency. If instruments for these basic measurements are not already part of the installation, they should be added. However, WirelessHART-based transmitters are available for all heat exchanger measurement applications: 

• Temperature instruments can be added to the process fluid and transfer fluid pipes without any penetrations. These sensors read through the pipe wall (Figure 4) and measure the interior fluid temperature accurately, regardless of ambient conditions. 
• With conventional temperature sensors, a single transmitter sends data from up to four sensors on one wireless signal. 
• Reading differential pressure (DP) across the process fluid inlet and outlet determines when fouling is beginning to accumulate, or if there is a tube leak. 

Figure 4: Emerson’s Rosemount X-well technology reads the temperature inside a pipe while staying outside the pipe, and it sends data via WirelessHART. Courtesy: Emerson

Data generated by these instruments goes to analytics applications purpose-built for heat exchangers, making these software tools easy to install, configure, and use. Algorithms look for conditions such as fouling by calculating efficiency and monitoring for deviations from baseline conditions, and results are displayed on preconfigured dashboards. The system identifies abnormal situations and sends alarms when certain conditions are met, such as a when fouling crosses a threshold.  

4. Lighting—avoiding wasted energy

Wasting power by lighting unoccupied areas often happens on an enormous scale at many process manufacturing facilities where lights stay on continuously, regardless of activity or time of day. In some cases, this stems from old metal-halide high-intensity discharge (HID) lamps, often deployed in hazardous areas and never turned off. When this waste is multiplied across hundreds, or even thousands of fixtures, the amount of power consumed is enormous. 

Facilities can reduce energy consumption and maintenance needs, while enhancing safety in harsh and hazardous locations, by replacing existing lights with new smart LED fixtures. These require up to 70% less energy than HID fixtures for equivalent light output, but they can save much more energy because they turn on and off when not needed, governed by motion detectors (Figure 5), timers and ambient light detectors. These fixtures communicate via WirelessHART, so they can be activated remotely, report periods when they are on and send diagnostic information on their condition to maintenance. 

Figure 5: Many plants waste energy by leaving lights on continuously. LED luminaires are more efficient than HID lights, and each fixture can be controlled individually to save energy. Courtesy: Emerson

Data can be collected and analyzed just like any other smart field device, showing exactly how much power is being consumed for lighting, along with its impact on sustainability metrics over a historical period. This approach has a side benefit of also providing a rough picture of activity within a facility, particularly at night, as lights respond to people moving around. 

Steps to sustainability

The projects described here deliver benefits because they use technologies—such as WirelessHART, pervasive sensing and data analytics solutions—to deliver results that positively impact all company stakeholders, surrounding communities and the global environment. These types of projects also increase overall profitability, so they are often self-supporting, easing implementation.   

Shane Hale is global director of business development, Emerson Automation Solutions. Edited by Chris Vavra, web content manager, Control Engineering, CFE Media and Technology, cvavra@cfemedia.com.   

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Keywords: sustainability, process manufacturing 

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