Black liquor recovery

Through the use of lab tests implemented by the pulp and paper companies in the United States and Canada it was determined that all but one manual technique were both unrepeatable and inaccurate. During some years ago the operators of black liquor recovery boilers have been able to take advantage of the latest teehnology to inspect the wall thickness of the near drum generator tubes. The technology utilises immersion ultrasound and automated computer... 

Black Liquor Recovery Boilers Many special boiler designs have been developed around the world for the pulp and paper industry, including black liquor recovery boilers. 

Various permutations of the black liquor recovery boiler design are used to combust soda liquors in the soda pulping process and alkaline earth liquors and ammonium liquor (red liquor) in the sulfite pulping process. 

Black Liquor Recovery Boiler Explosion List"... 

Black liquor Recovery furnaces for krali and soda-pulping processes 5-7... 

Yields of 50% and reduced energy consumption have been achieved by a history of innovation. Such innovation has included the Tomlinson black liquor recovery boiler, the Kamyr continuous digester and associated diffusion washer, multiple-effect evaporators, and low-odor concentrators. Economic advantages also have been gained by the development of systems for recovering extractives such as tall oil, fatty acids, and resin from the pulping liquor for sale as naval stores. Future innovations may focus on the lime kiln and other related systems. 

Black liquor recovery furnace fume Venturi and cyclonic spray 1.75 0.620... 

Fontes, Costa, and Azevedo [79] used 300 pm diameter Type R thermocouple in an alumina sheath with an external diameter of 4 mm and placed inside a 3 m or 5 m long water-cooled stainless steel probe to measure gas temperatures in a black liquor recovery boiler. Calculations showed the "true" temperature in the regions of highest temperature did not exceed measurements by more than 8%. Measurements were made at multiple elevations, multiple locations at each elevation, and at multiple insertion depths into the boiler. A traversing mechanism was used to insert the probe, which was checked frequently for deposition of black liquor particles and sulfate deposits. The temperatures ranged from approximately 700°C to 1000°C. 

With a few exceptions, coatings and linings are not used on the water and steam sides. In an EPRI project, about 50 turbine blade coatings have been evaluated, but none of these are being routinely applied. To reduce steam side oxidation in reheaters and superheaters, chromizing and chromating have been developed but these treatments are also not routinely applied. There is little use of composite materials with the exception of condenser tube sheets, which could be made of explosively clad stainless steel or titanium on carbon steel, and of the surfaces in the primary cycles of nuclear units where carbon or low alloy steels are protected by weld-deposited stainless steels. In pulp mill black liquor recovery boilers, stainless steel clad boiler tubes are often used. 

This paper presents some of the opportunities CFD offers when applied to analyse different combustion systems. Practical examples presented are ash deposition predictions on heat exchanger surfaces and walls in a bubbling fluidised bed furnace and detailed nitrogen oxide emission predictions for the same furnace type. Furthermore, the extension of a standard model using process specific data is presented for the fuel conversion process in a black liquor recovery furnace. 

Starting from an earlier work by Frederick and Hupa (1993) a new simplified black liquor droplet model is developed to replace the standard droplet model in CFD simulations of black liquor recovery furnaces. Liquor specific input data obtained from single droplet experiments is incorporated into the new droplet model. The model is implemented in a commercial CFD code and simulations in an environment that represents well the experimental setup of the single droplet furnace are performed (Figure 3). This way, model expressions for droplet swelling during devolatilisation and carbon release curves during devolatilisation and char carbon conversion can be validated. After this validation procedure the model can be used for full scale recovery furnace simulations. 

A methodology based on the minimisation of Gibbs free energy has been successfully adopted to describe the chemical composition of an industrial black liquor recovery boiler smelt. Moreover, the chemical composition reported in the literature from other industrial sources could also be satisfactorily reproduced using this technique. 

Hue gas from kratt black-liquor recovery furnace, sodium sulfate, sodium carbonate, sulfur dioxide, sulfur trioxide, hydrogen sulfide, methyl mercaptan, water, organic oxidation compounds, sodium compounds as sodium sulfate 10 Ib/min (venturi... 

---