Continuous AFEX Biomass Pretreatment with Ammonia Recovery
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Solution Overview
Problem
Current AFEX processes for biomass pretreatment are limited by their batch nature, high energy costs, and inefficient ammonia recovery and recycling, making them less commercially feasible and less effective in increasing the availability of cellulosic and protein materials in biomass.
Innovation Solution
A continuous AFEX process that involves contacting biomass with a swelling agent under elevated pressure to swell the fibers, followed by rapid depressurization in a second vessel to rupture the fibers, with a system for recycling and condensing the vaporized ammonia to reduce energy costs and improve ammonia recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous AFEX process is implemented using extrusion reactors, then the ability to commercially apply the process is improved, but the cost of capital expense and energy costs increases due to distillation processes required for ammonia recovery
Solution Approach 1:
The patent utilizes the phase transition of ammonia from liquid to vapor during rapid depressurization in the second vessel. This phase change enables the swelling agent to vaporize and rupture biomass fibers efficiently, eliminating the need for energy-intensive distillation processes while maintaining continuous operation capability
Solution Approach 2:
The process is divided into two distinct vessels: a first vessel for swelling under pressure and a second vessel for rapid depressurization and fiber rupture. This segmentation allows each vessel to be optimized for its specific function, improving overall efficiency and reducing energy requirements compared to single-vessel designs
2Productivity
If a continuous AFEX process is implemented, then the ability to commercially apply the process is improved, but capital expense increases due to additional equipment required for ammonia recovery and recycling
Solution Approach 1:
The second vessel serves multiple functions: it performs rapid depressurization, enables ammonia vaporization, facilitates fiber rupture, and collects the vaporized swelling agent. This multi-functionality reduces the need for separate equipment, thereby lowering capital expenses while maintaining continuous processing capability
Solution Approach 2:
The system recovers vaporized ammonia from the second vessel and recycles it back to the first vessel for continued use in swelling biomass fibers. This recovery and recycling mechanism reduces the need for additional ammonia input and eliminates the need for complex distillation equipment, lowering both capital expense and operational costs
3Quantity of substance
If rapid depressurization is used to vaporize ammonia and rupture fibers, then the availability of cellulosic material and proteins is improved, but ammonia recovery efficiency decreases without additional separation steps
Solution Approach 1:
The system establishes a feedback loop where vaporized ammonia from the second vessel is collected and recycled back to the first vessel. This continuous recycling ensures high ammonia recovery efficiency while maintaining the rapid depressurization process that ruptures fibers and releases cellulosic materials
Solution Approach 2:
The second vessel acts as an intermediary between the first vessel and the recycled ammonia stream. It facilitates the transition of ammonia from liquid to vapor phase and collects the vapor for recycling, enabling efficient ammonia recovery without requiring complex separation equipment
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
This approach enables efficient and cost-effective continuous treatment of biomass, enhancing the availability of cellulosic materials while reducing energy and capital expenses through efficient ammonia recovery and recycling.
Implementation Method 1
contacting the biomass material and a swelling agent in a first vessel under a pressure at least as great as the vapor pressure of the swelling agent and for a time sufficient to allow the swelling agent to swell fibers within the biomass material
Implementation Method 2
the pressure may be rapidly decreased to a level below the vapor pressure of the ammonia such that the ammonia vaporizes and ruptures the biomass fibers
Implementation Method 3
The vapor stream is then condensed, and used to treat the biomass material before the biomass material enters the first vessel
Data Source
AI summary
A method and apparatus for continuously treating a moist biomass feedstock is disclosed. The method includes treating a biomass feedstock with a swelling agent in a pressurized first vessel, transferring the feedstock to a second vessel at a lower operating pressure than the first vessel such that the biomass fibers rupture. At least portions the swelling agent, and/or the moisture are recycled in the process.