Zero-Emissions Refinery for Stillage Recovery
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Solution Overview
Problem
Current methods for handling raw stillage streams in alcohol distillation processes result in significant air emissions and water contamination, with existing thermal oxidizers generating additional environmental and energy problems.
Innovation Solution
A closed-loop energy refinery and purification system that eliminates the need for thermal oxidizers, achieving zero emissions by synergistically processing raw stillage to produce clean water, renewable natural gas, and other valuable by-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If thermal oxidizers are used to treat off-gas from stillage processing, then VOCs are destroyed, but air contamination and energy consumption increase
Solution Approach 1:
The patent converts the harmful VOC stream into a beneficial fuel source by using it as feedstock for anaerobic digestion, which produces methane for energy generation. This eliminates the need for thermal oxidizers while converting the harmful waste stream into a useful resource, thereby destroying VOCs without generating air contamination or requiring additional energy input
Solution Approach 2:
The patent extracts and separates the liquid stillage stream before it can be converted to harmful VOCs through evaporation. By using decanter centrifuges to separate solids from liquids and then directing the liquid stream to anaerobic digestion, the system prevents VOC formation at the source while capturing organic compounds for beneficial use
2Object-affected harmful factors
If thermal oxidizers are used to combust waste vapor stream, then off-gas is treated, but CO2, NOx, and SOx emissions are generated
Solution Approach 1:
The patent converts the waste vapor stream into a beneficial fuel source by using it as feedstock for anaerobic digestion, which produces methane for energy generation. This eliminates the need for combustion-based treatment that generates CO2, NOx, and SOx emissions, while still achieving off-gas treatment through biological conversion
3Use of energy by moving object
If digester produces anaerobic generated gas stream, then methane is produced for heating, but uncollected CH4 and contaminates are sent to TO requiring additional fuel
Solution Approach 1:
The patent implements a self-sustaining system where the anaerobic digester produces methane that is used to heat the digester itself and power the facility. The system captures and utilizes all produced gas, eliminating the need for external thermal oxidizers and additional fuel inputs. The digester serves its own energy needs, creating a closed-loop system that minimizes energy loss
4Productivity
If open type environment processing is used, then stillage separation is achieved, but water discharge contamination occurs
Solution Approach 1:
The patent converts the contaminated water discharge into a beneficial resource by using it as feedstock for algae cultivation. The nutrients in the stillage water promote algae growth, which is then harvested and used as additional feedstock for anaerobic digestion. This eliminates water discharge contamination while enhancing productivity through additional methane production
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 system effectively recovers clean water and valuable by-products while eliminating air emissions and water discharge, enhancing the efficiency and effectiveness of the separation process and creating a self-sustaining facility at net zero emissions.
Implementation Method 1
decanter centrifuge liquid solid separation
Implementation Method 2
anaerobic digester converting the liquid stillage stream into a methane rich stream
Implementation Method 3
TOs use natural gas to combust a lean waste vapor stream
Data Source
AI summary
In producing ethanol suitable for alcoholic beverages or fuels, the separation of stillage involves a complicated treatment system necessary to meet stringent air emissions standards and effluent discharge limits. High water content of stillage creates a difficult process mass flow balance configuration resulting in a large power demand and footprint. The present invention simplifies the production and usage of valuable stillage by-products and reduces net energy consumption and emissions to zero with a novel system and method involving a step sequence of: a solid liquid separation; at least one digester arrangement; a closed gas separation system; algae grow nutrient up-take system; a nutrient separation system; an ultra-filtration water system enabling the off-take by-products to be used by the system and an off-take market for the by-products and its purified water. All produced by-products including carbon dioxide (CO2) and methane (CH4) are used in the system or exported as products.