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Jet Cooker Liquefaction
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.
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
| Eliminate Steam Hammer | |
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
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
Power Plants & Refineries
Reverse Osmosis
ProSonix DSI Heating Solutions
- Angled Steam Injector is designed for hi viscosity, hi solids and difficult to pump slurries and sludges
- Low pressure drop of typically 1-2 psig
- Precise temperature control to +/- 1°F (-17°C)
- Expanded body allows for insertion of steam diffuser to maintain proper flow velocities thru heater
- Single or multi-stage heating for flow rates from 1 – 10,000 gpm
- High temperature rise up 250°F (121°C) in a single pass
- Standard carbon steel or 316SS. Optional alloys and wear coatings available for erosive or corrosive applications
- Designed to ASME B31.1; optional ASME, CRN or CE/PED certification
Well Suited For
- High solids, high viscosity and difficult to pump slurries
- Slurries with large particulate
- Fibrous slurries such as pulp stock and biomass
- Anaerobic digestion of municipal wastewater biosolids, animal by-products and biogas production
- Mining and mineral processing applications
The ProSonixTM I-Series Direct Steam Injection heater’s unique method of direct steam injection utilises internal steam modulation via an integral pneumatic actuator to accurately deliver the appropriate mass flow of steam for the required heating. This modulating design offers a precise method of steam control through a choked flow control delivery of the steam. 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 is metered to precisely control the heating of the liquid. This produces predictable results based on position of the stem plug. Through a variable-area steam diffuser, steam flow is metered at the point where steam and liquid first contact and mix.
Features & Benefits
- 3-Dimensional steam injector delivers up, down and side to side steam injection pattern to optimise steam mixing and rapid condensation
- Angled diffuser reduces flow disruptions and suitable for fibrous slurries
- Single point steam injector diffuser connection allows for complete fluid pass through clearance with no build-up points for fibrous materials
- Eliminates plugging and fouling from burn and scorch sensitive slurries and sludge’s
- Internally modulated steam injection controls mass flow of steam allowing for smooth and stable operation
- Energy savings as a result of low pressure drop across the PSX DSI heater
- Positional steam inlet allows steam inlet flange to be rotated in 360° for ease of steam piping connection
- Secondary internal steam shut-off (optional) for integral steam shut-off
Boiler Feedwater Heating
Boiler Feedwater Heaters via Direct Steam Injection
Power generating plants utilise steam boilers to produce electricity energy for their operation. These boilers often have feedwater heaters which are an integral part of the plant’s thermodynamic cycle. The presence of the heaters in the cycle improves the thermal efficiency of the power plant by lowering the amount of thermal energy required to generate a given amount of electrical by re-using produced steam in a heat exchanger to heat feedwater prior to the Deaerator.
Issues Associated with Boiler Feedwater Heating
- Heat exchangers are prone to mineral and scale build-up on the internal components. This scale build-up reduces their thermal efficiency and requires costly cleaning and replacement of damaged components
- Mineral and scale build-up can lead to a plugging/fouling issue which increases energy consumption from the condensate pumps
- Replacement of the heat exchangers requires considerable floor space and foundation improvement because of their size, weight and cleaning access requirements
ProSonix Direct Steam Injection Heater Solution
The PSX heater can be installed to heat up the returned condensate with low pressure steam from the turbine. Often times steam temperatures of 600°F (316°C) and feedwater temps of 400°F (204°C) are not uncommon. The key to efficient, safe and predictable steam injection is the use of internally modulated steam control and to inject steam at sonic velocity to achieve choked flow. By achieving choked flow, sonic velocity conditions can be achieved for steam injection. The use of an integral pneumatic actuator allows for sonic velocity steam injection for the PSX Heater to operate in a choked flow manner for good, non-violent mixing. The PSX heater is an internally modulated heater, with a variable position stem plug, that varies the mass flow rate of steam by changing the area in which the steam may pass. This type of modulation allows the full steam pressure to always be present at the point of injection, regardless of plug position.
Key PSX Heater Direct Steam Injection Benefits
| Eliminate Steam Hammer | |
- Stable operation the internally modulated steam control design of the PSX heater controls the steam mass flow and not the steam pressure, thus eliminating steam hammer and vibration issues
- Lower maintenance due to the PSX heater’s self cleaning design (no scaling or plugging/fouling)
- Low pressure drop across the PSX Heater (typically 1-2 psig) reduce pump integration issues and flow disruptions
- Economical installation as the PSX heater can be installed in the piping with no floor space requirements
- Precise temperature control, typically +/- 1°F (-17°C), allows for a more reliable heating process
- High turndown on both steam and liquid allow for process flexibility and process condition variations
Whitewater Heating
White water is a fine particle slurry used throughout the paper making process. Its name derives from fine fiber particles in the water that give it a milky white appearance. White water drains from the paper stock into a pit below the paper machine and is used for a variety of uses in the paper making process.
White water systems must periodically be cleaned to remove bacterial build up that occurs over time. This process is known as boil-out, in which the white water is raised to near boiling temperatures of around 180°F – 190°F (82°C – 88°C) to kill any bacteria in the system. A caustic solution is sometimes added to shorten the process and increase the effectiveness. The water is held at temperature until all bacteria is killed.
White water systems are typically heated by heating tank contents with steam spargers in the white water chest. Steam Injection Heaters that use a steam pressure reducing valve (PRV) experience a pressure drop in the steam pressure which leads to low velocity steam flow. Low steam velocity leads to poor steam mixing. Externally controlled steam injection heaters may lead to:
| Eliminate Steam Hammer | |
- Ineffective condensation of the steam from the spargers, damaging the chest walls leading to expensive repairs
- Steam escaping from the tanks and venting to atmosphere
- Hot and cold zones to be present in the whitewater chest, leading to variable stock temperatures at the paper machine head box
PSX Heater Solution
A PSX Jet diffuser heater is installed in the white water system to quickly raise the white water temperature to near boiling and then throttle back to maintain the desired temperature.
ProSonix unique method of steam injection utilises an internal steam control to precisely deliver the appropriate mass flow of steam for the required heating. This is achieved via and integral Pneumatic Actuator, and a variable position stem plug in the steam jet diffuser. We do not throttle or regulate steam pressure. This design offers a precise method of steam control through a choked flow control delivery of the steam. Choked flow is the phenomenon of accelerating a vapor to maximum velocity by creating a pressure differential through an engineered nozzle. By establishing choked flow, the steam mass flow can be metered to precisely control the heating of the liquid.
Key Direct Steam Injection Benefits
- Energy savings resulting from faster tank time and reduced heat loss to atmosphere
- Lower maintenance due to the PSX heater’s self cleaning design
- Improved safety due to better steam injection heating methods (elimination of steam hammer)
- Reduced operating costs by reducing costly machine down time
- Faster tank heat up time (~ 6-8 times that of traditional sparging) equals less machine downtime
Green Liquor Heating
Kraft pulp mills produce pulp from wood chips. Within the pulp production, a chemical process produces green liquor. Green liquor is a combination of recovery boiler smelt and dilute white liquor. Dregs are removed and liquor is sent to recausticising tanks to produce white liquor. Flows vary based on the size of the pulp mill and can range from 350-1400 gpm.
Recausticising is a two stage process used to recover chemicals from in the pulp production process. First stage reaction occurs with lime in a highly agitated vessel known as a Slaker at high temperatures 180°F – 215°F (82°C – 102°C). The second stage reaction occurs in a series of agitated tanks known as Causticizers where the reaction is completed.
Process Heating Challenges
Green liquor must be heated prior to the lime addition and temperature plays a key role in the chemical reaction.
- Sparging also has a tendency to create ‘hot spots’ in the slaker or causticisers, resulting in uneven reactions within the vessel. This can cause incomplete regeneration, chemical carryover or excessive reaction times. Sparging can also exaggerate dust formation from the vessel during operation producing maintenance issues
- Heat exchangers are subject to damage as green liquor is corrosive at elevated temperatures. Stainless steel welds, in particular, are susceptible to stress corrosion which can lead to shorted heat exchanger life and cross contamination between the steam and liquor
- Eductor style steam injectors with limited turndown (2:1) are prone to steam cavitation and accelerated wear
A PSX heater can be installed in-line upstream of the slaker. The PSX heater assures high velocity steam injection for rapid and complete condensation of the steam via our internally modulated steam injection design. Our Radial Multi-port Jet Diffuser assures uniform heating of the liquor. This results in a more uniform causticising reaction, thus reducing lime costs, and allowing better control of the process. The end result will be higher quality white liquor for use in the digesters and reduced operating costs. The PSX heater can also be supplied in appropriate metallurgy to address the thermal cracking that can occur when heating green liquor.
Key ProSonix Heater Benefits
- Fewer process upsets and reduced steam vibration from more efficient internally modulated steam injection
- High liquid turndown up to 10:1 to match the mill’s operating conditions
- Precise temperature control of +/- 1°F (-17°C) produces a higher quality liquor with less carry over
- Lower production costs from more efficient slaker operation and lower lime feed costs
- Reduced maintenance costs and downtime with appropriate metallurgy and elimination of steam cavitation
Wet End Starch Cooking
Wet end starch – Starch added at the wet end to the paper slurry can help increase the sheet strength. The starch will also act as binder for various additives and fillers such as Alum, Calcium carbonate and TiO2. When properly cooked, starch swells and its viscosity increases. Wet end starch is produced to give it a cationic charge. This allows the cooked starch natural adhesion properties to create a bond with the paper fibers. By connecting the fibers and additives in small ‘clumps’, leaving relatively clean water in between (flocculation), faster drainage of water leading to increased wire and machine speeds.
Size press starch – Many paper processes utilise a surface treatment known as sizing. Typically this is accomplished by applying a thin layer of starch during the drying of the paper in a section of the paper machine known as the size press. The function of the surface size treatment is to fill the voids in the paper sheet so any printing inks will sit on top the paper instead of penetrating into the sheet. Sized paper produces a clearer image when printed, than does un-sized, and allows for printing speeds through the printing press.
Issues Associated with Starch Cooking
- Poor slurry make-down and batch cooking of starch experiences clumping of starch molecules. This can lead to uncooked starch granules being sent to the headbox, where they either plug the wire or drop into the white water system
- Inconsistent starch viscosity can lead to build up on machine components. This starch buildup may eventually fall back onto the sheet, causing quality problems. If uncooked starch is present at the size press, it may cook on the sheet in the dryer section causing picks and tears in the sheet
- Batch cooking of starch in tanks can lead to inconsistent viscosity and batch to batch quality issues
PSX Jet Cooker Key Benefits
- More consistent starch viscosities
- Inline starch cooking allows for better response to process changes such as solids (%) changes
- OptiShearTM design allows for higher solids concentrations of starch slurry to be cooked
- Adjustable condensing tube position allows for pressure drop adjustments to be made
- Jet Cooker design promotes better mixing of steam and starch slurry for better cookout
- Reduced starch consumption reduces costs. Better drainage reduces maintenance, lower white water contamination and improved product quality
- Reduces localised wear issues associated with traditional Jet Cookers
PSX Jet Cooker Solution
The PSX Jet Cooker is specifically designed for cooking starch slurries. The unique internal design of the Jet Cooker allows wet end starch slurry to be cooked at higher concentrations (6-10%) and higher temperatures of 220°F – 260°F (104°C – 127°C). Size press starch slurry can also be cooked at higher concentrations (up to 35% solids) and higher temperatures of 220°F – 320°F (104°C – 160°C). The PSX Jet Cooker design promotes a very thorough mixing of the steam and starch slurry, effectively cooking all of the starch instantly. The turbulent mixing affect breaks up clumps that would pass through other steam heating devices or batch processes. This helps to ensure that the starch entering the headbox is completely cooked and extremely consistent in viscosity and temperature.