Effects of compositional variables on fouling behavior of thin stillage

Zheng, Yingying

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https://hdl.handle.net/2142/46601 Copy

Description

Title

Effects of compositional variables on fouling behavior of thin stillage

Author(s)

Zheng, Yingying

Issue Date

2014-01-16T17:55:46Z

Director of Research (if dissertation) or Advisor (if thesis)

Rausch, Kent D.

Department of Study

Engineering Administration

Discipline

Agricultural & Biological Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Corn processing
• thin stillage fouling
• ethanol processing

Abstract

In the US, ethanol is produced primarily from corn. There are two major commercial processes: corn wet milling (CWM) and dry grind corn (DGC). The DGC industry has grown and made 86% of corn ethanol by the end of 2008. During DGC processing, after distillation, the remaining nonfermentable material known as whole stillage is centrifuged to produce two processing streams; wet cake (30 to 35% solids) and thin stillage (5 to 10% solids). Thin stillage is concentrated to 25 to 30% solids in multi effect evaporators. The presence of fouling in evaporators can increase energy consumption as well as capital and labor costs. Limited studies have been conducted on fouling of corn ethanol processing. An annular fouling probe was used to evaluate compositional variables on fouling behavior of DGC thin stillage. The objectives of this study were to evaluate effects of starch and sucrose solids in fouling of thin stillage evaporators and to assess effects of wet cake in fouling of thin stillage evaporators. Four 100 L batches of thin stillage were collected from a dry grind plant and total solids concentrations were measured. Thin stillage was diluted with tap water so thin stillage plus starch or sucrose was 7% total solids. Fisher’s least significant difference method was used to detect differences among treatments for maximum fouling resistance and fouling rates after 25, 60, 120, 150 and 300 min (P < 0.5). Adding 2% starch to thin stillage increased fouling rates compared with adding 2% sucrose or thin stillage alone. The treatment with additional sucrose showed similar fouling behavior compared to raw thin stillage with 7% total solids. Batches of thin stillage (60 L) were collected to investigate effects of wet cake solids on fouling behavior. Adding 2% wet cake to thin stillage increased the fouling rates compared to thin stillage with 7% total solids. Fouling resistances increased with starch addition, as well as with wet cake addition, at equal total solids contents. Insoluble starch addition had larger effects than soluble sucrose addition. Sucrose alone did not cause increased rapid fouling.

Graduation Semester

2013-12

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http://hdl.handle.net/2142/46601

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Copyright 2013 Yingying Zheng

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