Instrumentation, Control Systems Contribute to Sustainability

Process controls underlie effective water, energy saving strategies in ethanol production.
By Leigh Parnell | May 14, 2013

The concept of sustainability has been around for decades, though only recently felt on a large scale. Many companies are showing that environmentally friendly and economically sound are not mutually exclusive concepts.

Siemens AG has estimated that its products and services have enabled its customers to substantially reduce their greenhouse gas emissions. In 2011, Siemens helped its customers reduce annual CO2 emissions by about 320 million tons, an amount equal to the total annual CO2 emissions of Berlin, Delhi, Hong Kong, Istanbul, London, New York, Singapore and Tokyo combined.

There is much discussion in the media today about green business, sustainable initiatives, and the like. But it can be difficult to decipher how these issues are being played out at the individual and community level. The good news is: sustainable business practices are happening in villages, towns and cities around the globe.

Take Havelock, Ontario, for example. This small central-eastern Ontario community is home to Kawartha Ethanol Inc., a midsize ethanol producer. Kawartha Ethanol began operations in 2010, and has a production capacity of 80 MMly (21 MMgy)—enough to fill more than 1.4 million average-size vehicle gas tanks. The company’s aim is to operate in the most sustainable way possible. How it achieves that goal, bringing sustainable business to small-town Ontario, is a story that both Kawartha Ethanol and Siemens are proud to tell.

From Grain to Greener Gasoline
Fuel-grade ethanol, which is 99 percent pure alcohol, has a number of important properties that make it an excellent automotive additive. It is clean-burning and has a high percentage of oxygen (35 percent), which means fuel combustion is more efficient. When used in vehicles, ethanol decreases carbon monoxide emissions by up to 30 percent, according to the Canadian Renewable Fuels Association. Ethanol is not in itself a complete solution to global warming but, with an average daily consumption of 88.6 million barrels of oil around the world, as reported by the International Energy Agency in 2012, this type of greenhouse gas reduction is an important step on the path to sustainability.

So, how do Kawartha Ethanol’s production processes contribute to a greener environment? The primary focus is in three areas: reducing water usage, reclaiming heat and saving energy. Control systems and multiple analytical devices play a significant role in these sustainability solutions.

Water Usage Reductions
While it takes 1,851 gallons of fresh water to produce a single barrel of crude oil, most ethanol plants can reuse about one-third of the total water they consume says the CRFA. At Kawartha Ethanol, plant designers have gone above and beyond this in their water reuse initiatives.

The plant has four containment areas surrounding its chemical storage vessels and another two surrounding its fuel storage tanks. These concrete barriers prevent chemicals from leaching into groundwater in the event of a spill. Since these areas are outside, they naturally collect rainwater. None of this water goes to waste. Pumps move rainwater back into the ethanol process, at the stage where corn is mixed with water to make a slurry. Reusing this water from the containment areas is a water-saving solution created by Kawartha Ethanol—and an effective one at that.

Containment areas, of course, serve to prevent damage from accidental spills. In addition, if a spill occurred in the containment area, any rainwater that had been gathered would be contaminated and could become unusable for the mixing stage of the ethanol process. Kawartha Ethanol has implemented a number of safety measures to prevent spills in these areas. The plant uses digital pressure transmitters for continuous level monitoring on its chemical storage vessels. These transmitters monitor the hydrostatic pressure in the vessels and convert the measurements to level readings. Vibrating point level switches are used as backup for the facility’s continuous systems, providing overfill protection for the chemical vessels and throughout the production process. To monitor recirculated water, as well as other material moving from process to process, Kawartha Ethanol uses a number of flowmeters combined with transmitters.

Heat Reclamation
During the manufacturing process, temperature and pressure control is crucial to ensuring a quality final product and a safe working environment. Throughout ethanol production, temperature measurement is most important to operators.

Kawartha Ethanol uses product-to-product heat exchangers to redistribute thermal energy throughout the plant. Heat exchangers circulate high-temperature liquids or slurries with low temperatures, without mixing these materials.

Following are three examples of where heat exchangers are used in the process:

• In hydrolysis, enzymes break down the corn mash into simple sugars, creating a great deal of heat. The mash must be cooled from 85 to 41 degrees Celsius (185 to 106 degrees Fahrenheit ) before moving to the fermentation stage. Cooling waters circulate in order to lower mash temperatures to within the optimal range. This process can reclaim more than 40 C of heat without using extra energy to cool the mash.

• After distillation, centrifuges separate the whole stillage into cake and liquid, which is then concentrated through a series of evaporators that use waste heat from distillation. The two products are then recombined to form distillers grains.

• In the energy center, flash steam is created in the boiler condensate system, where liquid moves from a high-pressure to lower-pressure areas. Instead of using energy to heat process water for use during ethanol production, heat exchangers circulate water with flash steam.

Temperature and pressure control instruments play an important role in these heat reclamation systems. Kawartha employs temperature transmitters to monitor the mash cooler, making sure that the slurry enters the fermentation stage at the correct temperature.

The pressure created during the ethanol process also needs to be closely monitored. Pressure transmitters measure areas such as the boiler condensate system. Because too much pressure can be dangerous, these devices are equipped with safety functions and advanced diagnostics to ensure accuracy. Valve positioners accompany all of the temperature and pressure transmitters in the facility and provide intelligent diagnostics.

Energy Savings
Ensuring that no heat is lost in transport is another important initiative for plant designers at Kawartha Ethanol. Customized insulation wraps are secured around pipes and vessels containing heated material. If operators ever need access to instruments, they can easily unwrap the insulation, perform any needed maintenance and then rewrap it.

All of the process instruments monitoring these pipes and vessels at Kawartha are connected through a Profibus network, sending information to a distributed control system (DCS); Kawartha uses Siemen’s Simatic PCS 7 system. In the control room, operators can see immediately if a piece of equipment requires maintenance, and respond quickly. The system provides high-performance engineering tools, with features such as alarm management, process safety and asset management. As Bill Harris, electrical supervisor at Kawartha Ethanol sums up, “Our process includes hundreds of Siemens instruments measuring flow, level, pressure, and temperature—all feeding back to a centralized DCS system via the Profibus network. We rely on the accuracy and dependability of this system to ensure that we operate efficiently and safely.”

Support for Sustainability
Two decades ago in his book, “The Ecology of Commerce: A Declaration of Sustainability,”  Paul Hawken declared: “Leave the world better than you found it; take no more than you need; try not to harm the environment; make amends if you do.”

These words echo the drive behind the sustainability initiatives currently in place at Kawartha Ethanol. If anything, the need for greener practices in industry has only increased over the past two decades, and will not soon disappear. Siemens process instruments play an important role in helping companies like Kawartha Ethanol operate their plants efficiently, by providing operators with precise process information.

Recently named one of Canada’s Greenest Employers for 2012, Siemens Canada demonstrates its corporate values as well as its products are aligned with sustainable practices. Striving to “leave the world better than they found it,” Kawartha Ethanol and Siemens prove that green business is indeed possible, both in small towns and on a global scale.

Author: Leigh Parnell
Sensors and Communication Manager, Siemens Canada
905-315-6933
leigh.parnell@siemens.com

 

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