Starch Processing

Ethanol Production

PSX Jet Cookers use ethanol (ethyl alcohol or grain alcohol) that is produced through a liquefaction process whereby a starch is converted to a sugar, which is then converted to an alcohol product and referred to as ethanol. Ethanol production requires a starch (corn, wheat, rye) based feedstock to supply the conversion process. The grain mash must go through a cook process, to raise the slurry’s temperature. In the Primary Liquefaction Stage, slurry is then pumped through a pressurized jet cooker at 221°F (105°C) and held for 5 minutes. The mixture is then cooled by an atmospheric or vacuum flash condenser. After the flash condensation cooling, the mixture is held for 1–2 hours at 180°F – 190°F (82°C –  88°C) to allow the enzymes time to work.

• The Jet Cooker is a critical to evenly hydrolyse and heat the grain mash slurry. The relationship between the Jet Cooker’s steam injector and condensing tube produces a pressure drop to help maximise shear action to improve starch conversion.
• Poor alignment of the steam injector and condensing tube can cause artificially high delta P, pre-mature localised wear, non-uniform shearing action and an increased use of enzymes to compensate.
• The poor alignment of steam injection and condensing tubes lead to overdriving the condensing tube which can reduce starch slurry flow rates through the Jet Cooker and increases energy consumption by placing a higher demand on the slurry pumps.
• Single point condensing tube drive systems lead to premature failure of drive components.

PSX Jet Cooker Solution:

The PSX heater is state of the art Jet Cooking technology. The steam condensing tube has multiple bearing surfaces, thus providing precise alignment with the steam injector which assures radial flow of starch slurry in the Jet Cooker. The unique drive system rotates the condensing tube thus eliminating localised wear.

ProSonix Direct Steam Injection Key Benefits:

• Multiple bearing surfaces assure proper alignment between the condensing tube and steam nozzle thus improved shear action and reduces enzyme consumption
• Industrial drive system eliminates single point drive failure points improving reliability
• Reduced pressure drop improves performance and reduces energy consumption
• Lower maintenance costs with improved drive system reduces internal wear
• Reduced plant air consumption as drive system utilises AC Motor

Download brochure

Corn Wet Mill – Fructose & Corn Syrup

Corn wet milling is the process of separating the corn kernel into starch, protein, germ and fiber in an aqueous medium prior to fermentation. The primary products of wet milling include starch and starch derived products (e.g. high fructose corn syrup and ethanol), corn oil, corn gluten and corn germ. All agricultural crops and residues contain starch, which is a polymer of glucose, a six-carbon sugar. To produce ethanol from grain, the starch portion of the grain is exposed and mixed with water to form a mash. The mash is heated and enzymes are added to convert the starch into glucose.

There are two primary areas where direct steam injection heating can provide value for the Wet Mill process. They are the steeping process and the primary liquefaction or starch cooking process.

Steeping Process

The steeping facilitates the separation of the grain into its many components. In the wet milling process, steeping is the process where the grain is first soaked or ‘steeped’ in water and dilute sulfurous acid for 24-36 hours. Steep tanks may hold from 70.5 to 458 cubic meters (m3) (2,000 to 13,000 bushels) of corn, which is then submerged in a current of dilute sulfurous acid solution at a temperature of about 125°F (52°C). To reach this temperature, hot water is added to the steeping tanks. After steeping, the corn slurry is processed through a series of grinders to separate the corn germ. The remaining fiber, gluten and starch components are further segregated using centrifugal, screen and hydroclonic separators.

PSX Water Heater Advantages

• Internal steam modulation design of the PSX heater controls the steam mass flow and not the steam pressure thus eliminating steam hammer and vibration issues
• Low pressure steam may be used since the steep system operates at low pressure
• Low maintenance due to the PSX heater’s self cleaning design
• Stable operation due to better steam injection heating methods (elimination of steam hammer)
• Precise temperature control allows for a more reliable heating process.+/- 1°F (-17.2°C)
• Reduced pressure drop (typically 1-2 psig) reduces pump energy demand
• Direct mechanical control of the steam injector allows for linear process heating control
• PSX is controlled by the plant PLC/DCS or local controller with no proprietary software required
• Ease of installation as the PSX heater can be installed in the piping requiring no floor space

Primary Liquefaction – Starch Cooking Process

After the steeping and separation process, the starch is physically and chemically prepared for fermentation. The milled grain is mixed with process water, the pH is adjusted to about 5.8, and an alpha-amylase enzyme is added. The grain mash must go through a cook process, to raise the slurry’s temperature. In the Primary Liquefaction Stage, slurry is then heated with a pressurised jet cooker at 221°F – 228°F (105°C – 109°C). The mixture is then cooled by an atmospheric or vacuum flash condenser and then the mixture is held for 1–2 hours at 180–190°F (82°C – 88°C) to allow the enzymes time to work.

Previous first generation jet cookers suffered from various issues:

• Poor alignment of the steam injector and condensing tube force the system to run at artificially high pressure drops (delta P), causing premature localised wear, non-uniform shearing action and an increased use of enzymes to compensate
• The poor alignment of steam injection and condensing tube leads to over driving the condensing tube which can reduce starch slurry flow rates through the Jet Cooker and increase energy consumption by placing a higher demand on the slurry pumps
• Single point condensing tube drive systems lead to premature failure of drive components

PSX Jet Cooker Key Benefits:

• Multiple bearing surfaces provides precise alignment between steam injector and condensing tube to promote radial slurry flow which assures uniform and radial flow of the starch slurry
• Improved jet cooking performance. The PSXJet Cooker is designed for ethanol and starch process applications, where optimisation of the pressure drop results in improved starch cook-out performance and a reduction in enzyme costs. The uniform alignment between the Condensing Tube and Steam Injector for more uniform flow and eliminates the need for over driving the combining tube to compensate for misalignment
• Reduced maintenance by eliminating the single point bolt stud connection which is a common failure point in other Jet Cookers
• No proprietary software or controls required. The system can be operated directly from the plant DCS/PLC
• No plant air consumption as the drive system utilises an AC motor
• Positional steam inlet allows the steam inlet to rotate 360° to meet the incoming steam piping regardless of the slurry inlet and discharge positions for ease of installation

Download brochure

Jet Cooker Starch Liquefaction

The OptiShear Jet Cooker is designed for starch cooking, wet mill processing of starch, ethanol production, as well as fructose and alcohol production. ProSonix unique method of direct steam injection utilises internal steam modulation via an integral Pneumatic Actuator and variable position steam plug, to accurately meter the mass flow of steam, through choked flow conditions. Choked flow is the phenomenon of accelerating a vapor to maximum velocity by creating a pressure differential through an engineered opening. By establishing choked flow, the steam mass flow can be metered to precisely control the heating of the liquid. This produces predictable results based on the position of the steam plug. Through a variable-area steam diffuser, steam flow is metered at the point where steam and liquid first contact and mix.

• Starch slurry processing is designed for starch slurries with solids concentration of up to 40%
• The OptiShear is well suited for all types of starch such as corn, potato, wheat, rice, and cassava or tapioca
• High velocity steam and turbulent mixing injection via internally modulated steam control and variable position steam plug for vibration free operation
• Precise temperature control of +/- 1°F (-17.2°C) for reliable heating performance
• The OptiShear can be installed in any orientation and requires no floor space for installation
• Automatic or manual operation simplifies process integration
• Can be installed in any orientation. High temperature rise up 250°F (121°C) in a single pass
• Materials of construction. Standard carbon steel or 316SS with optional wear coatings available for erosive slurry conditions
• Standard ANSI class connections (NPT threaded or RFF flanged) for 150 psig steam, with optional 300 psig available. Design standards- designed to ASME

Adjustable Slurry Gap Optimizes Starch & Steam Mixing, Reducing Enzyme Use

In starch cooking, proper agitation or “shear” is required to optimize the thermal effect of the steam on the starch particles. The OptiShear Jet Cooker is equipped with an adjustable Condensing Tube (CT). The adjustable CT can be positioned to vary the gap relative to the steam nozzle, creating a narrow slurry gap. This narrow gap between the CT & steam nozzle optimizes the steam exposure to the thin ribbon of starch slurry as it enters the CT. By changing the position of the CT relative to the face of the steam nozzle, back pressure inside of the OptiShear can be optimized to reduce uncooked starch and enzyme usage.

Radial Slurry Flow

In the OptiShear design, the condensing tube and steam nozzle interface is truly coaxial, ensuring the starch slurry gap is uniform throughout the full 360° flow path. The tube rests on multiple bearing surfaces so there is no movement of the tube relative to the injector except to adjust the gap.

Advanced Drive System

The tube movement in the ProSonix heater to adjust the starch gap is accomplished using a threaded engagement. The tube is rotated and an external thread moves the tube towards or away from the injector (nozzle). Moving the tube in this way changes the orientation of the tube inside the heater, causing any wear spots of the tube to move as well. This has the beneficial effect of evening out the wear of the internal parts, extending their operating life.

Download brochure