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Oilseed Processing Modernization Opportunities

This paper focusses on some of the basic and also advanced opportunities available to a typical oilseed crusher, primarily on a soybean processor, although many of the concepts discussed are applicable to others in the feed and grains processing industry.

The objectives are to examine some of the cost-reduction opportunities for an existing crushing and refining operation. As the products of these plants are generally sold in the commodity markets, processing plants are generally price-takers as opposed to a price-setter. It is assumed that any modern processor will produce a product of nearly identical quality and quantifiable characteristics, which is the nature of a commodity-based operation. Hence, we will focus on primarily on opportunities to reduce operational costs, although no discussion would be complete without some emphasis on new value-added opportunities. In addition, this paper will touch on some new technologies and market trends that are either already in place or expected to come into force soon.

Opportunities for Cost Reduction
Steam and Process Leaks - as we begin the discussion, we should emphasize the fact that many basic cost-reduction opportunities can be undertaken with little cost. Steam and process leaks are easily identified and in most cases corrected with little effort. For example, while I was recently visiting a major Asian processor, the chief engineer was interested in investing in the latest energy efficient meal desolventizer. This was certainly a good thing and an easily justifiable use of capital. However, when walking through the plant, I noticed several easily correctable problems, including steam leaks, cyclones emitting meal dust, and spilled meal being washed down the drain. Eliminating these losses would have provided as much savings as investing in new equipment, but correcting these maintenance problems was not as fun as considering a new project, so these were neglected. Just a 2 mm steam leak wastes over $1,500 USD per year, and having several of these quickly adds up. Steam trap failures are not as obvious as a leak, but are just as significant in terms of wasting money.

Boiler Efficiency (R)C broilers deserve special mention as opportunities for cost reduction. If the boile is not operating at least 85% efficiency, a lot of your energy cost is wasted. Recovering heat from blowdown and deaerators, and maximizing the amount of condensate recovery are a few more ways to reduce the operating costs. One of the most significant invoices a company receives is the bill from the electric company, and power factor correction and peak load shedding are ways to maximize efficiencies. There are other electrical demand isssues to be aware of, such as sizing a motor closer to the actual job demand. As a typical example, a conveyor with a 6 kw actual load may be supplied with an 11 kw motor. While there is no doubt the extra reserve power is nice, and may be justified in certain cases. However, during normal operations, this motor will now be loaded at about 50% of its rated capacity, resulting in a lowered efficiency and power factor, and will consume substantially more electricity than a properly sized motor.

Insulation (R)C this is another quick-payback opportunity that never seems to become a priority. Conside assigning a young engineering intern to identify heat losses and if the maintenance department doesn¡ãO have time, consider selecting an outside contractor to perform the job. Although this does represent a substantial cash outlay, this is a better option than waiting-payback of insulating of hot equipment usually pays itself back in a matter of months.

Tight control (R)C tight control over process variables is another opportunity for the commodity processor Products are generally sold on trading rule guidelines-of moisture, fiber, protein, fat, and other quantifiable factors. Tightening control over these parameters is one of the largest revenue-enhancing opportunities available to the processor. For example, a 1000 tpd soybean processor that can tighten control over moisture content by 0.1% will enhance the bottom line by nearly $50,000 USD per year. Clearly investing in process control and instant-results lab equipment is one of the quickest ways to enhance profitability.

In summary, many of these cost reduction opportunities are not very exciting or much fun, but are very real. Identifying these opportunities should be one of the first priorities of the processor seeking to enhance their profitability.

Reducing Operating Costs
Assuming that the bulk of the low cost opportunities have been explored, the next step is to look toward the operation, with an eye on capital investments that provide at least a 3-year payback. The preparation is the obvious first starting point, where there has been considerable interest in producing high protein (hypro) meal. The standard soybean operation cannot increase the amount of protein so our options are to take other things away. Generally, this means removing the hulls, which contain about 35% fiber, which increases the meal protein content. While many of the hulls can be removed after the extracted meal is ground (known as tail-end dehulling), the most common approach is to remove the hulls prior to solvent extraction (front-end dehulling). While the traditional approach has been to dry and temper the bean prior to cold aspirating the soybean cracks, the industry has essentially moved toward the various hot dehulling options because of higher efficiencies and lowered operating and installed costs.

The Dehulling System
There are at least 2 variations on the hot dehulling theme. The full hot dehulling system has become the industry standard, suitable for processing a wide variety of beans, including freshly harvested varieties. A recent variant that has enjoyed substantial attention is known as the warm dehulling system. This system takes advantage of the fact that the hulls on imported beans are not as tightly adhered as fresh harvest beans, and can be removed by a less-intensive separation (and hence the term warm dehulling). In addition to the lowered product costs, the hot dehulling systems provide an improved meal quality and a lowered NOL extracted oil loss. If there is no current demand for hypro, the processor can still enjoy improved qualities and lowered operational costs by use of the combined bean dryer and conditioner system.

Extraction Plant Considerations
The extraction plant is the next area of examination. Probably one of the most significant developments in this area has been implementation of the Schmacher DTDC. With this countercurrent flow unit, hexane recovery is maximized using a minimum of direct-contacting steam. Schumacher DTDCs also provide an optimum toast/PDI control as well, allowing the plant to provide a meal with substantially lowered residual hexane content while simultaneously reducing the overtoasting associated with older designs.

Mineral oil absorption systems are also considered a standard on a modern plant. While some older, smaller capacity designs still rely on refrigerated vent condensers for discharge air hexane recovery, the mineral oil system provides much enhanced hexane recovery, and overall plant safety.

There are many opportunities for excess heat recovery and transfer in the extraction system as well. Mineral oil interchangers, oil to miscella exchangers, vapor contactors, and oil and/or waste water to boiler feedwater exchangers provide very positive economic benefits and these applications should be fully explored.

Improved Refinery Operations
With continuing energy and environmental concerns, refineries have received a great deal of attention toward improving operations. For example, the traditional neutralization system has long depended upon a single, or even double, washing step to remove the soaps from the once-refined oil. New technology has been introduced to eliminate the washing step eliminating oil loss, capital and operating costs of the washing system, and the costs associated with wash water treatment and disposal. The traditional 2-filter bleaching system has been enhanced by addition of a 3rd, pre-bleaching filter, reducing the amount of clay used (and oil lost) by about 30%. The deodorizer, which is one of the most energy intensive operations of the entire crushing system, has enjoyed enhanced heat recovery options. New generations of vacuum systems, which traditionally require 8 kg of steam for every 1 kg of stripping steam are now used extensively to reduce not only energy costs, but also reduce the amount of effluent ¡ã¡Þdirty¡ã¡À water that the typical refinery must deal wit

Deodorizer System
One of the most significant advancements to the deodorizer system has been development of the various generations of packed column systems. These units generally consist of a high temperature, low residence time packed column stripping section where the volatiles are flashed in a matter of seconds followed by a somewhat lowered temperature heat bleaching section to allow for effective heat bleaching. This design provides an excellent quality finished product while minimizing utility costs and oil losses. As the high temperature exposure time is limited, packed column units minimize the amount of trans-fatty acids generated during processing. Recent packed column designs are equipped with a double shell, eliminating air contact and fire concerns.

Packed column strippers also lend themselves well when retrofitting existing tray type deodorizers. In a typical application, a stripping section is added, with the existing tray unit converted to a heat bleacher. In addition to providing a superior quality oil and reduced operating cost, this approach also allows for a substantial system capacity increase-often exceeding 50% of the original design.

Recent Technological Developments
Now that we¡ãOve examined some of the ¡ã¡Þbasic¡ã¡À technology improvements that have generally b well integrated into many plants, the next step would be to look toward some of the recent developments that early adaptors have integrated into their operations. We begin with the extraction system, where 3 relatively new systems have experienced substantial success. The first is the zero effluent discharge, or ZED system. In a typical extraction plant, about 50-100 lpm of high BOD wastewater is discharged to a waste treatment system. The ZED system eliminates about 90% of this discharge, with the remaining 10% introduced into the meal, providing a closed-loop evaporation/condensing system for this otherwise wastewater. In addition to essentially eliminating the water discharge, this system also reduces the amount of makeup water that is provided to the plant.

Another innovation is the vapor/solvent interchanger, which replaces the traditional vapor contactor. With this unit, fresh hexane is heated by waste gasses, reducing the load on the solvent/water separator tank and providing a more effective manner for maximizing heat recovery. The third development of great interest is the vapor solvent recovery, or VSR, tray, which is integrated into the DTDC, located immediately under the live steam sparging tray. This system recovers otherwise lost steam vapors and traces of hexane, and can reduce the overall extraction plant steam requirements by as much as 15%.

Recovery System
Refineries have also benefited by some new developments as well. One very interesting developing has been the fatty acid recovery systems developed for seed oils refining operations. During normal processing a low value ¡ã¡Þacid oil¡ã¡À product is produced, which is sold mostly as technical grade fa This system is capable of separating out and distilling the high value fatty acids, which typically represent about half of the acid oil volume, leaving the low value ¡ã¡Þblack oil¡ã¡À available for sale as fe fat. Dual temperature deodorizing systems are also of substantial interest. The distillate generated as a co-product of deodorizing contains valuable tocopherols and sterols, and rather than produce a single relatively low value blended product, these systems are capable of removing the higher value materials as a separate product. Bleaching clay oil recovery is another example of new technology to cure an old problem. Spent clay has been historically treated as a troublesome waste, often classified as a hazardous material because of its tendency for spontaneous combustion. By separating and recovering the neutral oil, the clay can be treated as an inert material, and sometimes reused for certain oils.

Value-added Alternatives
Companies such as Crown are continually developing new value-added alternatives, and there are several new innovations out on the horizon. Biodiesel is certainly a growth opportunity and is seen as one of the developing markets for soybean and rapeseed oil. However, economics do not favor production of biodiesel at this time, and the industry is dependent upon government mandates and subsidies, which can change at any time. Edible soy products are growing in popularity especially in Asia, and the prospects for soy protein concentrate (SPC) and soy protein isolate (SPI) are becoming increasingly attractive. One exciting development, with the first commercial operating just now being built in the US, is the use of supercritical fluids (especially carbon dioxide) to extract oil from soybeans. This technology holds several promises, including an all-natural and efficient extraction process, extremely high quality oil produced, and very limited denaturing of the soybean protein. While the economics will probably never allow complete replacement of solvent extraction, this technology will shine for edible and organic soy product markets.

Conclusion
The nature of our business is generally that of a price taker, so the goal is to become the most cost effective producer of quality commodity products. To that end, first take a critical look at existing operations to discover low cost opportunities for reducing costs. The next logical step is to consider the ¡ã¡Þbasic¡ã¡À plant improvements, such as efficient DTDCs, deodorizers, etc. After these have be fully considered, investigate the more cutting edge options, such as the VSR tray and fatty acid systems that early adaptors are currently utilizing. Finally, stay current in the industry as new value- added and evolving technologies are introduced.

Tags · Oilseed · Processing · Modernization · Feedstuffs

17.02.2008. 09:33