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[[file:SantaFeRecoveryBoiler.JPG|thumb|SantaFeRecoveryBoiler]] [[file:Svartlut_76.jpg|thumb|Svartlut 76|left]] [[file:EarlyTomlinsonRB.gif|thumb|EarlyTomlinsonRB]] [[file:Black_liquor_nozzle.JPG|thumb|Black liquor nozzle|left]] [[file:NetheatingvalueBlackLiquor.jpg|thumb|NetheatingvalueBlackLiquor]] [[file:DrySolidsvsYear.jpg|thumb|DrySolidsvsYear]] {{Short description|Industrial boiler used in the pulp and paper industry}}
{{Infobox industrial equipment
{{Infobox boiler
| name = Recovery Boiler
| name = Recovery boiler
| image = [[File:SantaFeRecoveryBoiler.JPG|thumb|A recovery boiler in operation]]
| image =
| caption = A recovery boiler in operation
| caption =
| uses = Recovery of chemicals and energy from black liquor
| classification = Boiler
| industry = Pulp and paper industry
| fuel type = Black liquor
| application = Pulp and paper industry
| inventor = G.H. Tomlinson
| year of invention = 1934
}}
}}


A '''recovery boiler''' is a type of industrial [[boiler]] used in the [[pulp and paper industry]]. Its primary function is to burn [[black liquor]], a byproduct of the [[kraft process]], to generate steam and recover valuable chemicals used in the pulping process. The recovery boiler plays a crucial role in the [[chemical recovery]] cycle of the kraft process, making it an essential component in the production of [[paper]] and [[pulp]].
A '''recovery boiler''' is a crucial component in the [[pulp and paper industry]], used primarily to recover chemicals and energy from [[black liquor]], a byproduct of the [[kraft process]]. The recovery boiler plays a vital role in the chemical recovery cycle, enabling the recycling of chemicals and the generation of steam and electricity.


== History ==
==History==
The recovery boiler was invented by G.H. Tomlinson in 1934. Before its invention, the recovery of chemicals from black liquor was inefficient and hazardous. The introduction of the recovery boiler significantly improved the efficiency and safety of the chemical recovery process, leading to widespread adoption in the pulp and paper industry.
The development of the recovery boiler was a significant advancement in the kraft process, allowing for more efficient chemical recovery and energy production. The first recovery boilers were developed in the early 20th century, with significant improvements in design and efficiency occurring over the decades.


== Operation ==
==Function==
The recovery boiler operates by burning black liquor, which contains organic materials and inorganic chemicals. The combustion process generates heat, which is used to produce steam. This steam can be used for various purposes, including powering [[turbines]] to generate [[electricity]] and providing process heat for the mill.
The primary function of a recovery boiler is to combust black liquor, which contains organic material and inorganic chemicals. The combustion process recovers the inorganic chemicals as a smelt, which is then processed to regenerate the cooking chemicals used in the kraft process.


The inorganic chemicals in the black liquor, primarily sodium compounds, are recovered in the form of a molten smelt. This smelt is then dissolved in water to form [[green liquor]], which is further processed to regenerate the chemicals used in the kraft process.
===Combustion Process===
Black liquor is sprayed into the recovery boiler through specialized nozzles, such as the one shown in [[File:Black_liquor_nozzle.JPG|thumb|A black liquor nozzle]]. The liquor is burned in the furnace, releasing heat that is used to produce steam. This steam can be used to generate electricity or provide process heat for the mill.


== Components ==
===Chemical Recovery===
A typical recovery boiler consists of several key components:
During combustion, the inorganic chemicals in the black liquor are reduced to a molten smelt, which is collected at the bottom of the boiler. This smelt is then dissolved in water to form green liquor, which is further processed to regenerate white liquor, the active cooking chemical in the kraft process.
* '''Furnace''': The main combustion chamber where black liquor is burned.
* '''Superheater''': A set of heat exchangers that increase the temperature of the steam produced in the boiler.
* '''Economizer''': A heat exchanger that preheats the feedwater entering the boiler, improving overall efficiency.
* '''Air system''': Supplies the necessary air for combustion.
* '''Smelt spouts''': Channels through which the molten smelt is discharged from the furnace.


== Advantages ==
==Energy Production==
The recovery boiler offers several advantages:
The recovery boiler is a significant source of energy for a pulp mill. The heat generated from burning black liquor is used to produce high-pressure steam, which can drive turbines to generate electricity. This process is illustrated in the [[File:NetheatingvalueBlackLiquor.jpg|thumb|Net heating value of black liquor]].
* Efficient recovery of chemicals, reducing the need for fresh chemical inputs.
* Generation of steam and electricity, contributing to the energy needs of the mill.
* Reduction of environmental impact by minimizing waste and emissions.


== Challenges ==
==Environmental Impact==
Despite its advantages, the recovery boiler also presents some challenges:
Recovery boilers help reduce the environmental impact of the kraft process by recycling chemicals and reducing the need for fresh chemical inputs. They also reduce emissions by efficiently burning organic material in black liquor.
* High capital and maintenance costs.
* Potential for severe corrosion and fouling due to the harsh conditions inside the boiler.
* Safety risks associated with handling and processing molten smelt.


== See also ==
==Challenges and Innovations==
Recovery boilers face challenges such as corrosion, fouling, and the need for efficient combustion. Innovations in materials, design, and control systems continue to improve the efficiency and longevity of recovery boilers.
 
==Also see==
* [[Kraft process]]
* [[Kraft process]]
* [[Black liquor]]
* [[Black liquor]]
* [[Pulp and paper industry]]
* [[Pulp mill]]
* [[Chemical recovery]]
* [[Chemical recovery]]
* [[Boiler]]


== Related pages ==
==References==
* [[Kraft process]]
* Smook, G. A. (1992). ''Handbook for Pulp & Paper Technologists''. Angus Wilde Publications.
* [[Black liquor]]
* Adams, T. N., & Frederick, W. J. (1988). ''Kraft Recovery Boiler Physical and Chemical Processes''. American Paper Institute.
* [[Pulp and paper industry]]
 
* [[Chemical recovery]]
{{Pulp and paper industry}}
* [[Boiler]]
{{Industrial equipment}}


[[Category:Boilers]]
[[Category:Pulp and paper industry]]
[[Category:Pulp and paper industry]]
[[Category:Chemical processes]]
[[Category:Industrial equipment]]
[[Category:Industrial equipment]]
{{Boiler-stub}}

Latest revision as of 00:47, 10 December 2024

Template:Infobox industrial equipment

A recovery boiler is a crucial component in the pulp and paper industry, used primarily to recover chemicals and energy from black liquor, a byproduct of the kraft process. The recovery boiler plays a vital role in the chemical recovery cycle, enabling the recycling of chemicals and the generation of steam and electricity.

History[edit]

The development of the recovery boiler was a significant advancement in the kraft process, allowing for more efficient chemical recovery and energy production. The first recovery boilers were developed in the early 20th century, with significant improvements in design and efficiency occurring over the decades.

Function[edit]

The primary function of a recovery boiler is to combust black liquor, which contains organic material and inorganic chemicals. The combustion process recovers the inorganic chemicals as a smelt, which is then processed to regenerate the cooking chemicals used in the kraft process.

Combustion Process[edit]

Black liquor is sprayed into the recovery boiler through specialized nozzles, such as the one shown in

A black liquor nozzle

. The liquor is burned in the furnace, releasing heat that is used to produce steam. This steam can be used to generate electricity or provide process heat for the mill.

Chemical Recovery[edit]

During combustion, the inorganic chemicals in the black liquor are reduced to a molten smelt, which is collected at the bottom of the boiler. This smelt is then dissolved in water to form green liquor, which is further processed to regenerate white liquor, the active cooking chemical in the kraft process.

Energy Production[edit]

The recovery boiler is a significant source of energy for a pulp mill. The heat generated from burning black liquor is used to produce high-pressure steam, which can drive turbines to generate electricity. This process is illustrated in the

File:NetheatingvalueBlackLiquor.jpg
Net heating value of black liquor

.

Environmental Impact[edit]

Recovery boilers help reduce the environmental impact of the kraft process by recycling chemicals and reducing the need for fresh chemical inputs. They also reduce emissions by efficiently burning organic material in black liquor.

Challenges and Innovations[edit]

Recovery boilers face challenges such as corrosion, fouling, and the need for efficient combustion. Innovations in materials, design, and control systems continue to improve the efficiency and longevity of recovery boilers.

Also see[edit]

References[edit]

  • Smook, G. A. (1992). Handbook for Pulp & Paper Technologists. Angus Wilde Publications.
  • Adams, T. N., & Frederick, W. J. (1988). Kraft Recovery Boiler Physical and Chemical Processes. American Paper Institute.

Template:Pulp and paper industry