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The CRG process

Description

The Cold Recycle Granulation (CRG) process is modernizing the Urea Granulation world. This is state of the art Granulation Technology, where energy saving, low investment costs and high product quality are combined in a ground shaking new layout and a revolutionary production process.

The CRG process is the result of GGT’s extensive R&D efforts in a quest to optimize solid product flows, improve internal circulation within the spray zone and boost cooling capacity.

The CRG process consists of a fluidized bed granulator containing the hydraulic urea sprayers but no cooling section . The granulator is operating at reduced product layer thickness thanks to the patented sprayer layout. Urea plus biuret content of the urea melt to the sprayers is typically 96% but 95% is no problem.

In line with the granulator comes the fluidized bed cooler operating at identical product layer thickness as the granulator.

An air sieve removes an amount of still hot fines in the first section of the cooler.

The remaining product is cooled down to end product temperature in the second section of the cooler operating still at the same reduced product layer thickness. The size of the cooler is reduced by installing water cooled cooling plates in the cooler.

Oversize and remaining fines are screened out at end product temperature. The cold crushed oversize and cold fines are recycled to the granulator together with the hot fines from the air sieve.

Granulator air and cooler air is cleaned in separate low pressure drop wet scrubbers. Dust in the stack is only 20 mg/Nm3 thanks to the patented double temperature scrubbing of the granulator air.

Characteristics and advantages of the CRG process

Low energy consumption thanks to:

  • Reduced product layer thickness resulting in less heating of the fluidization air fan and consequently reduced amount of needed air
  • Hydraulic urea sprayers use reduced amount of atomization air at reduced pressure
  • Low pressure drop scrubbers reduce the power consumption of the exhaust air fan(s)
  • Reduced amount of recovered urea dust combined with lower water content of the urea solution, typically 55% due to low atomization air and higher granulator scrubber temperature

Low investment thanks to:

  • low building height, typically 27m total height
  • low requested building strength, highest load bearing floor is at the granulator bottom at 17m, vibrating screens are located below the granulator
  • reduced granulator and cooler strength because of low fluidization air fan pressure and low scrubber exhaust fan suction pressure
  • bucket elevator capacity is only 30% of standard, lifts only fines and crushed product
  • reduced air ducting, air enters the scrubbers from the top and leaves the scrubbers from the side

Improved product quality thanks to:

  • low product moisture due to the combination of the GGT hydraulic sprayers and GGT sprayer layout
  • low end product dustiness due to slow cooling and highly improved product polishing in the cooler

Alternative cooling options

Cooling plates

Description:

Specially designed to maximize the heat transmission between warm granules and cold cooling water and to minimize the risk of urea deposition on the cooling plates

Advantages:

  • Boosting the cooling capacity of the cooler
  • Optional for grass root plants or as revamp tool

Air Sieve Technology

Description:

Removing a large stream of under-size product from the cooler at a stage where this product is not yet cooled down to end temperature. This stream is re-injected in the granulator as warm seed material.

Advantages:

  • Boosting the cooling capacity of the cooler
  • Optional for grass root plants or as revamp tool
  • Lowering the load to the vibrating screen(s)

Scrubbing Technology

As part of a complete granulation unit project or as a separate service

Characteristics:

  • Horizontal type scrubbers
  • Low pressure drop
  • Special designed scrubber pads that are able to handle huge quantities of scrubbing solution per m²
  • Patented double temperature scrubbing technology

 

 
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