Sweetening Ethanol, Sugar Mix

One of Brazil's largest sugar producers processes its cane crop for consumable sugar and fuel ethanol, while co-generating electric power for internal use and sale to the grid. With fuel markets at current heights, the company's challenge is to increase its throughput capacity and alcohol yield to meet the world's rising demands for ethanol without significant new capital investment.
By Brandon Henning, GE Fanuc September 1, 2008

One of Brazil’s largest sugar producers processes its cane crop for consumable sugar and fuel ethanol, while co-generating electric power for internal use and sale to the grid. With fuel markets at current heights, the company’s challenge is to increase its throughput capacity and alcohol yield to meet the world’s rising demands for ethanol without significant new capital investment. (Given the highly competitive nature of ethanol production in Brazil, the company asked not to be named.)

The biggest incentive for industry expansion is the elevated price for sugar in export markets and the development of flex-fuel car engine technology where alcohol can be used alone or mixed with gasoline in any proportion. Currently in Brazil, 90% of new cars sold have flex-fuel engines and ethanol accounts for about 20% of the vehicle fuel supply. Gasoline in Brazil is typically sold with a blend of 20% ethanol and 80% gasoline, but flex-fuel engines can use a blend of 0% to 100% of either fuel.

Most of Brazil’s ethanol is made from sugar through a yeast-driven fermentation process and distillation. This process requires less energy overall than corn-based ethanol produced in the U.S. As a result, Brazilian ethanol creates 8.2 times more energy than was used to produce it, compared to 1.5 times for comparable corn-based fuel.

Sugarcane is harvested manually or mechanically and shipped to several hundred distilleries around the country in specially-built trucks. The distilleries are typically owned and run by big farms or farm consortia located near the producing fields, mostly in São Paulo state.

At the mill, sugarcane is roller-pressed to extract the juice, leaving behind a fibrous residue called bagasse. The juice is then fermented with yeast, breaking down sucrose into CO 2 and ethanol, which is distilled yielding hydrated ethanol. Burning bagasse produces heat for distillation and drying, and even electricity for use by the plant itself or to be sold to utilities.

Strategic automation

While the business strategy for most sugar producers is to build additional new mills to satisfy growth, this company is very interested in keeping a high level of technology in its current mills to increase existing asset efficiencies. The company believes that improving process automation will reduce downtime while improving quality, consistency, and profitability. Management also wants to be able to track the genealogy of its product from raw materials through scheduled execution of batch processes, as well as monitor and analyze batch efficiencies and variation.

One of the most effective ways for companies to keep costs low is to monitor and tightly control overall equipment effectiveness (OEE). Therefore, the company’s road to enhanced automation started with a pilot of GE Fanuc’s Proficy Plant Applications efficiency module at one site where sugar cane is received and pressed.

This module provides a comprehensive view of key factors including equipment downtime, quantity, and event sequences. When properly applied, it can provide detailed, real-time reporting to support increased production throughput using the same equipment, people, and materials.

The pilot was started at one plant as a test prior to making a decision on when and how to implement at two other sites. As the May-to-November growing and processing season progressed, the new system helped control problematic downtime which raised overall production. Consequently, the pilot quickly expanded to three sites based on those initial results.

As the number of system deployments expanded, so did the implementation depth. Proficy Plant Applications batch execution module was added to the fermentation operation area. This utility helps manage recipes following ISA S88 guidelines to protect intellectual property. The S88 standard defines a common set of models and terminology that describe and define batch manufacturing systems.

In addition to the Plant Applications modules, the company has installed Proficy Portal and Proficy Historian, encompassing 10,000 tags and 30 clients. The expanded system also includes Proficy HMI/SCADA Cimplicity, PACSystems controllers, Series 90-30 PLCs, and Genius blocks are also part of the automation system. Proficy’s open architecture allows these products to interface with the company’s existing ERP systems as needed.

The project has been implemented by a team from system integrator STI Canada and STI do Brasil in several phases. The first phase replaced some management reports and the Quality/Lab features of the existing MES solution with targeted benefits that include controlled downtime and quality control.

Control system migration

Before the company started the pilot, the operating control platform was a custom-developed solution that had been in place for about four years. Management had been disappointed that it did not provide the data speed and availability required, so they decided to look for another MES.

As company managers began to compile a list of business requirements, several quickly emerged as critically important and moved to the top. All agreed that avoiding unplanned downtime was most critical. The plant runs 24/7, and an interruption of even 30 minutes will show up as a significant difference in monthly production. Drilling deeper into performance data, it was clear that the grinder was the area where most downtime problems began. Here the cane is ground and the juice extracted. From there the juice can be used as a feedstock for finished sugar or ethanol.

Deciding how much goes into each process depends on current market conditions for the finished product. Price volatility isn’t usually drastic enough to drive daily or even weekly changes, but production schedulers can change allocations two or three times per production season. Because the company generates income from both processes, it has greater options than competitors who produce only ethanol. The new control system helps support this flexibility, facilitating changes as required to create the most profitable balance.

Ethanol can be very profitable. Sugar is currently the most efficient and cost-effective feedstock for large-scale commercial ethanol production and Brazil has the largest sugar cane crop in the world. With growing global demand, Brazil’s producers have invested heavily in innovative technologies to lower the cost of production. As recently as 1980, it cost producers more than $2.50 to make a gallon of ethanol. Now, thanks to technology improvements, a gallon costs just $0.75, and the search for process improvements should find ways to drive the cost still lower.

But this story isn’t just about ethanol. There are alternatives available on the sugar side as well. Different grades of sugar can be obtained from the same raw material, each with its own market price. Today, the process finishes by mixing all of the grades together in one batch that is then sold based on the percentage of different qualities.

Engineers are working on ways to use the Plant Applications platform to control the production process in a way that will allow separation of the finished product into different silos according to the different grades, which will ultimately allow schedulers to produce specific grades based on market demand.

Maintaining quality

A significant piece of the automation puzzle involves the laboratory portion of the process. At present, most ethanol producers simply keep lab results in spreadsheets as part of a manual quality control program. If a batch tests poorly, it needs to be reprocessed consuming additional production time and cost.

However, after implementing Proficy Plant applications, the company can link production parameters with quality measurements. This increases efficiency and effectiveness of the process, reducing rework.

As the world tries to reduce its dependence on oil, renewable fuels like ethanol are becoming increasingly critical. Commercial success will depend on maintaining efficiency and competitive price levels.

Author Information
Brandon Henning is global food and beverage industry manager, GE Fanuc Intelligent Platforms. Reach him at brandon.henning@ge.com .