Comprehensive model of alkali-salt deposition in recovery boilers.Application: Engineers and designers can use this model to understand problems with fouling and plugging and can help determine how to gain improvements in recovery boiler Recovery boiler is the part of Kraft process of pulping where chemicals for white liquor are recovered and reformed from black liquor. In the process lignin of the wood, bound in black liquor at this phase, is burned and heat generated. operations and design. Deposit formation in recovery boilers is a major cause of boiler plugging and lost productivity in the pulp and paper industry The global pulp and paper industry is dominated by North American (United States, Canada), northern European (Finland, Sweden) and East Asian countries (such as Japan). Australasia and Latin America also have significant pulp and paper industries. , inorganic material that is generated in the furnace and entrained by the combustion gases as particles and vapors deposits on surfaces of the boiler. Deposit formation in the convection pass represents one of the major limitations of both the operation and design of the boiler. Ash deposition rates and properties have been quantitatively measured in laboratory experiments and in situ In place. When something is "in situ," it is in its original location. for black liquor Black liquor is a byproduct of the Kraft process, (also known as Kraft pulping or sulfate process) during the production of paper pulp. Wood is decomposed into cellulose fibers (from which paper is made), hemicellulose and lignin fragments. . Full-scale measurements have also characterized particle sizes at various locations in the convection pass of the recovery boiler. The authors demonstrate the relevance of recent measurements on boiler operation. Algorithms for alkali-salt deposition were implemented into a three-dimensional numerical model of a recovery boiler. The model includes: 1. Mechanisms for particle formation and chemistry 2. Particle deposition and adhesion 3. Deposit thermal properties. These algorithms are fully coupled with models for turbulent flow, black liquor combustion, and heat transfer in the boiler. Model predictions are presented for particle deposition in the convection pass of a commercial recovery boiler. The distributions of gas velocity and gas temperature have a considerable effect on particle deposition on tube banks, deposit temperature, and absorption heat flux. Modeling can be used qualitatively to elucidate e·lu·ci·date v. e·lu·ci·dat·ed, e·lu·ci·dat·ing, e·lu·ci·dates v.tr. To make clear or plain, especially by explanation; clarify. v.intr. To give an explanation that serves to clarify. problems with fouling and plugging, leading to more effective use of convection surfaces and sootblowing. With greater validation, the model will be a useful engineering tool for anticipating ash behavior with changes in fuel composition, operating conditions, and design. Wessel is an advisory engineer with the Functional Technology and Computational Analysis Group, Babcock & Wilcox, Barberton, Ohio Barberton is a city in Summit County, Ohio, United States. The population was 27,899 at the 2000 census. It is part of the Akron metropolitan area and has the ZIP code 44203. Geography Barberton is located at (41.015805, -81. , USA; Baxter is a professor of chemical engineering at Brigham Young University Brigham Young University, at Provo, Utah; Latter-Day Saints; coeducational; opened as an academy in 1875 and became a university in 1903. It is noted for its law and business schools. , Prove, Utah, USA. Email Wessel at rawessel@babcock.com or Baxter at larry_baxter@byu.edu |
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