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Based on: Industry Standards and Best Practices

Languages: English

Sample Transcript

The fireside of the recovery boiler is where the combustion of the strong black liquor and the chemical recovery processes simultaneously take place. Strong black liquor enters the recovery boiler from the brown stock washers containing 65 to 85% dry solids. The recovery boiler uses strong black liquor as its main fuel and during normal operation functions with black liquor as the only fuel. The cooking chemicals flow out of the recovery boiler as molten salts or smelt and are turned into green liquor in the dissolving tank. This green liquor is sent to the recausticizing process for conversion to white liquor.

Kraft Recovery Boilers - Fireside

Training Time: 32 minutes

The fireside of the recovery boiler is where the combustion of the strong black liquor and the chemical recovery processes simultaneously take place. The gases from the combustion of the black liquor leave the fireside and carry the heat to the heat transfer section of the boiler. The recovered chemicals flow out of the bottom of the boiler fireside and are converted into green liquor. The module describes the operation and components of the fireside of the kraft recovery boiler.

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Training Content + Interactive Quizzes

Smelt is a combination of molten chemicals which flow from the bottom of the boiler into the dissolving tank

Black liquor droplets sprayed into the boiler quickly evaporate and then burn

The flow of water into the boiler and the flow of steam out of the boiler are carefully monitored as a technique for detecting leaks

Learning Objectives

  • Describe what occurs in the fireside of the kraft recovery boiler
  • Describe the components of black liquor
  • Identify and describe the two sections of the kraft recovery boiler
  • Identify and describe the primary process flows
  • Describe the operation of the liquor system
  • Describe the operation of the air system
  • Describe the black liquor combustion process in the fireside
  • Describe the purpose of the auxiliary burners
  • Define "carryover"
  • Identify and describe some of the safety hazards and safe work practices associated with the fireside
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Kraft Recovery Boilers - Fireside FAQs

Where does the organic material in black liquor come from?
The organic material in black liquor is made up predominantly of chemically dissolved lignin, the glue material in wood.

What is "recovered" in a recovery boiler?
Both heat and inorganic cooking chemicals are recovered in the recovery boiler.

How is black liquor introduced into the boiler?
Concentrated black liquor is pumped directly into the firebox of the boiler through multiple nozzles .

What is smelt?
Smelt is a combination of molten inorganic cooking chemicals (primarily sodium carbonate and sodium sulfide) which collects in the bottom of the boiler.

How is smelt removed from the boiler?
Smelt flows out from the bottom of the boiler as a molten liquid. A steam jet breaks the stream into small droplets which then fall into the dissolving tank.

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