Biomass Cooling via Flash Evaporation and Detoxification
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Solution Overview
Problem
Current biomass treatment methods face challenges in cooling thermally treated biomass to the optimum enzymatic activity temperature range of 40-60°C without dilution, managing pH adjustment, and reducing toxic compounds like carboxylic acids and furfural, which hinder enzymatic hydrolysis and fermentation processes.
Innovation Solution
A method involving a pressurized reactor where biomass is hydrolyzed with partially condensed steam, discharged by steam explosion into a blow tank maintaining pressure above atmospheric, diluted, and then cooled in a flash tank to produce a cooled aqueous slurry, with latent heat recovery and pressure management to optimize enzymatic treatment, avoiding coolant dilution and toxic compound retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If biomass is cooled by mixing with cold coolant water, then cooling efficiency is improved, but slurry dilution occurs below optimal concentration
Solution Approach 1:
The patent utilizes evaporative cooling where water evaporates from the hot biomass slurry, absorbing heat and cooling the mixture without adding external coolant. This phase transition approach achieves efficient cooling while maintaining slurry concentration, avoiding the dilution problem associated with mixing cold liquid coolant.
2Temperature
If biomass is cooled by mixing with cold coolant water, then cooling efficiency is improved, but operational cost increases due to dilution liquid removal
Solution Approach 1:
Evaporative cooling utilizes the latent heat of vaporization to remove heat from the slurry. The evaporation process itself is the cooling mechanism, eliminating the need for large volumes of coolant that would require energy-intensive separation and removal downstream, thereby reducing operational costs.
3Temperature
If biomass is discharged to atmospheric pressure blow tank, then cooling occurs, but toxic compounds remain in the slurry
Solution Approach 1:
The patent employs a vacuum flash tank that operates at reduced pressure to facilitate rapid evaporation and stripping of toxic compounds such as furfural and carboxylic acids from the biomass slurry. The vacuum conditions enhance the removal of these harmful volatiles, effectively extracting them from the liquid phase and reducing their concentration in the treated slurry.
Solution Approach 2:
The vacuum flash tank utilizes rapid phase transition where water and dissolved toxic compounds evaporate instantly under reduced pressure. This flash evaporation process efficiently separates and removes toxic compounds from the slurry while achieving rapid cooling, addressing both cooling and detoxification requirements simultaneously.
4Productivity
If pH is adjusted to optimal range for enzymatic activity, then enzymatic hydrolysis efficiency is improved, but additional processing steps are required
Solution Approach 1:
The vacuum flash tank process performs preliminary pH adjustment and detoxification simultaneously during the cooling phase. By removing toxic compounds that interfere with enzymatic activity and adjusting pH conditions during the flash evaporation process, the system prepares the slurry for optimal enzymatic hydrolysis without requiring separate, additional processing steps.
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 method efficiently cools biomass to optimal enzymatic activity temperatures, reduces toxic compound concentrations, and recovers energy, enhancing enzymatic hydrolysis efficiency and reducing operational costs while maintaining environmental sustainability.
Implementation Method 1
pre-hydrolyze biomass sugars in a reactor in which hemicellulose sugar is dissolved from biomass at elevated temperature and pressure
Implementation Method 2
The temperature in the reactor is typically around 200° C. and the pressure is in the range 15 to 20 bar
Implementation Method 3
the absolute pressure is maintained above atmospheric pressure to facilitate recovery of secondary heat as low-pressure steam
Implementation Method 4
The hydrolyzed biomass is further cooled and detoxified by flash evaporation for further treatment
Implementation Method 5
water and other volatile compounds evaporate to equilibrium to the pressure prevailing in the blow tank
Implementation Method 6
recovering the latent heat from the first vaporous aqueous stream withdrawn from the blow tank
Data Source
AI summary
The present invention relates to an improved method and device for treating biomass in which thermally treated biomass is discharged from a pressurized reactor and introduced into a blow tank and then a flash tank, wherein the absolute pressure in the blow tank is maintained above atmospheric pressure and the absolute pressure in the flash tank is maintained below atmospheric pressure. The slurry of biomass separated in the flash tank is then enzymatically treated. The heat from the thermally treated biomass is recovered from the latent heat of a vaporous aqueous stream withdrawn from the blow tank.