Continuous cooking enzymatically degraded native starch sorts in semi-automated or automated modes. The degrading agent is the enzyme α-amylase. The starch solutions prepared this way are suitable for usage as surface applications in size or film presses

Performance groups: EKK500,EKK1000,EKK2000
Performance range: 350 – 2 200 kg/hr
Slurry concentration: 22 to 30 %
Outlet concentration: 10 to 18 %
Power input: 4 to 12 kW

Function brief description

Powder starch is dosed by means of precise worm dosing device into a slurry tank where it is mixed with water and slurry is formed. The slurry concentration depends on the starch sort and use. The enzyme is pumped into the slurry tank in an exact ratio to starch. Starch slurry is continuously pumped by means of screw pump into a static mixer where saturated steam is injected to preheat slurry and to achieve proper conversion dynamics. The coking mixer is followed by a converter where native starch is degraded for a preset time at a precisely set temperature. The degradation is finished in a cooking tube following the mixer. The cooking temperature is kept on the required value depending on the starch sort by means of control circuit. 

The machinery design and safety comply with the EU and EAC industrial standards.

The cooking tube is followed by another static mixer bringing diluting/cooling water into the cooked starch solution. The outlet concentration is controlled by means of dilution water quantity. Its throughput is controlled by control circuit. Starch diluted into a required outlet concentration and cooled down to 60 to 95°C enters the storage tank and it is ready for further use If diluting water cannot cope with cooling cooked starch below 100°C an expander aiding cooling starch is installed between the cooker outlet and the storage tank. The process is identical for all the starch sorts. The enzyme dose controls the cooked starch final viscosity.

Cooker main parts

• Powder starch source – a hopper intetrated in a support frame or certain type of a lowor high-volume silo for higher starch demand (the silo accessories are designed separately for particular applications)
• Precise worm dosing device with a drive and arms preventing arising cavities
• Precise enzyme dosing pump of a diaphragm type with internal diagnostics
• Cooling box for storing a can with enzyme
• Slurry tank with a high-performance agitator
• System controlling water throughput into the slurry tank-depends on the cooker type
• Slurry pump with performance control -depends on the cooker type
• Slurry filter screening coarse mechanical impurities
• Static mixer for steam injection to preheat slurry entering the converter
• Circuit for automatic preheating cooking temperature control
• Converter with a slow-running agitator
• Converter pump with a performance control depending on the cooker type
• Cooking tube
• Static mixer for dilution/cooling water input
• Circuit for an automatic/manual dilution /cooling water throughput control
• Set of measuring & control elements
• Electric switchboard (wherever required)
• Support frame

Cooker concept

K compact – slurry unit installed in the frame together with the cooking part

O separate – slurry unit installed separately from the cooking part

Control system

– none – the cooker is controlled by means of an external control system

S Simatic – the cooker is controlled by means of an external control system

Filling slurry tank with water

A automatic – water throughput into the slurry tanks is controlled by an automatic control valve system

P float – water throughput into the slurry tank is controlled by a float valve

Slurry throughput control

F frequency converter – the slurry pump is controlled by a frequency converter

– the slurry pump without a performance control

Back pressure control

A  automatic – the cooking tube pressure is controlled by an automatic control valve

M manual – the cooking tube pressure is controlled by a manual valve

Dilution control

A automatic – the dilution water flow through the cooking tube is controlled by an automatic control valve

Flushing

P – water for quick flushing is connected to the slurry pump suction side

– flushing cooker enabled by water connected to the slurry tank

Cooker performance control

A  automatic – the cooker works with a performance proportional control

–  the cooker works with a constant performance in an on/off mode

Starch hopper

N  – a starch hopper installed in the support frame is part of the cooker

–  no hopper,the starch source is a silo

Software

The EKK cookers are delivered including SW enabling a fully automated cooker operation in predefined steps – sequences. The sequences enable cooking and flushing automated modes at reproducible values before and after finishing the cooking process, including a precise control of enzyme dosing, conversion time and temperature, cooking/enzyme deactivation temperature. The cooker can be switched into a manual mode and the operation can be carried out by means of control board installed on the switchboard front door. 
During the cooker operation the cooking process conditions like media parameters, functions and statuses of particular cooker key elements and control circuit statuses are monitored; if any parameter deviates from a control range an alarm message is generated and saved in anal arm bank.
The cooker performance is usually controlled depending on the cooked starch storage tank level height either in an on/off mode (the cooker works with a constant performance, starts on the bottom level and stops after reaching the top level) or it works with a variable performance depending on the storage tank level fall speed.

In special cases, when the cooker is part of a large process unit, it may be delivered without a control system and SW. Then it is controlled from a paper machine priority system.

Technical data

Starch sort: native 
Starch origin: potato, corn, wheat, tapioca
Starch source: hopper integrated in the cooker support frame 3 (volume 100 to 400 dm ) 3 medium or large volume silo (volume 5 to 150 m )
Starch packing: paper sacks 25 to 40 kg “Big-Bags” 600 or 1 000 kg road tanker, starch stored in a high-capacity silo
Starch dosing: precise worm dosing device with arms preventing arising cavities driven by an electric motor with a gear and arms driven by a final gear. 
Enzyme dosing: precise dosing pump with performance control and flow measuring
Conversion time: 20 minutes
Cooking time: 2 minutes for all starch sorts
Heating medium: saturated steam 4 to 5 bar abs
Preheating temperature: approx. 80 to 85°C depending on the enzyme sort
Heating temperature: 125 to 145°C depending on the starch sort (the enzyme is also inactivated in the cooking phase)
Water: fresh or treated without mechanical impurities, minimum pressure 3.5 bar
Instrument air: dew point -20°C, pressure 5 bar
Performance change speed: dQ = 5 kg/min or a ramp change

The converter design

The converter design respects the performance requirements which are put on the cooker. They influence the converter volume so that the conversion time is 20 minutes, no matter how the performance is high. The requirements on the ratio between the minimum and maximum cooker performance influence the converter shape.

For the cookers working in narrow capacity ranges a cylindrical converter with bottom filling is designed. For cookers working in the capacity range of approx. 0.7 to 1, a cylindrical converter with a top filling is designed.

For cookers working in the capacity range of approx. 0.5 to 1, a conical converter with a top filling is designed.