Two-Stage Drying Process for Distillery Stillage
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Solution Overview
Problem
Current drying processes for wet cake and condensed thick stillage from starch-based ethanol distilleries, particularly those using broken or boiled rice, face inefficiencies and nutritional value degradation due to high temperature requirements and limited capacity utilization, resulting in unsuitable DDGS for animal feed, especially in regions lacking natural gas and with specific challenges in handling viscous CTS.
Innovation Solution
A two-stage drying process utilizing a steam tube rotary dryer followed by a spin flash dryer/pin mill type flash dryer to dry wet cake and condensed thick stillage at lower temperatures, achieving the desired moisture content and nutritional quality of DDGS without requiring natural gas, and allowing full utilization of CTS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single stage rotary dryer is used to dry wet cake and condensed thick stillage, then the drying capacity is sufficient, but the product temperature becomes too high which degrades nutritional value
Solution Approach 1:
The drying process is divided into two distinct stages: a first stage rotary dryer for bulk water removal, followed by a second stage flash dryer for final moisture reduction. This segmentation allows each stage to operate at optimized temperatures, with the first stage handling high moisture content at moderate temperatures and the second stage completing drying at lower temperatures to preserve nutritional value.
Solution Approach 2:
The first stage dryer acts as an intermediary that pre-dries the wet cake and CTS mixture before it enters the second stage flash dryer. This intermediate processing step reduces the moisture burden on the final drying stage, enabling it to operate at lower temperatures while still achieving the target moisture content.
2Productivity
If high temperature drying is used to achieve desired moisture content, then drying speed increases, but nutritional components such as protein, fat, minerals and vitamins are degraded
Solution Approach 1:
The drying process is divided into two distinct stages: a first stage rotary dryer for bulk water removal, followed by a second stage flash dryer for final moisture reduction. This segmentation allows each stage to operate at optimized temperatures, with the first stage handling high moisture content at moderate temperatures and the second stage completing drying at lower temperatures to preserve nutritional value.
Solution Approach 2:
The process changes the temperature parameter across different drying stages. The first stage operates at moderate temperatures suitable for bulk water removal, while the second stage operates at lower temperatures (below 100°C) to achieve final moisture content while preserving heat-sensitive nutritional components like vitamins and amino acids.
3Adaptability or versatility
If region lacks natural gas infrastructure, then alternative energy sources are required, but drying process becomes less efficient and more costly
Solution Approach 1:
The drying system is designed to be fuel-agnostic, accepting multiple energy sources including biomass-derived steam, biogas, or electricity. The first stage rotary dryer and second stage flash dryer can both operate with steam heating, which can be generated from various sources including biomass combustion or waste heat recovery, making the system adaptable to regions without natural gas infrastructure while maintaining energy efficiency.
Solution Approach 2:
The system can utilize waste heat from the ethanol distillation process or biomass waste from the distillery as energy sources for drying. This self-service approach converts local waste resources into useful energy, eliminating the need for external natural gas infrastructure while maintaining energy efficiency and reducing operational costs.
4Ease of manufacture
If condensed thick stillage is not fully utilized, then transportation and storage logistics are simplified, but valuable nutritive components are wasted
Solution Approach 1:
The process merges wet cake and condensed thick stillage into a single blended feed product (DDGS) that combines the advantages of both streams. This integration allows full utilization of CTS nutritive components while producing a homogeneous final product with consistent quality and moisture content, eliminating the need for separate handling and storage of different byproducts.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process maintains nutritional value and achieves the desired 10-12% moisture content in DDGS, enhancing its quality and digestibility as an animal feed supplement, while being energy-efficient and cost-effective, allowing for full utilization of CTS and eliminating the need for additional fibrous matrices or additives.
Implementation Method 1
a mixture of wet cake and the condensed thick stillage is dried at lower product temperature by first drying in steam tube rotary dryer
Implementation Method 2
drying in steam tube rotary dryer
Implementation Method 3
further dried using spin flash dryer/pin mill type flash dryer to obtain the dry DDGS with required 10-12% moisture content
Data Source
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AI summary
The present invention relates to an improved process for the drying of wet cake and condensed thick stillage in a grain based distillery particularly obtained from Broken Rice as feed substrate, using two stage drying. The two stage drying includes steam tube bundle rotary drying followed by spin flash dryer/ pin mill type Attritor flash drying. The Dried Distillers Grain Soluble so obtained has particle size of 600-2000 microns substantially free from large agglomerates and 10-12% moisture content suitable for animal feed supplement/fish feed. The present invention also relates to the dryer/ equipments wherein the process of the invention may be carried out.