Biomass Slurry Liquefaction via Flash Cooling and Depressurization
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Solution Overview
Problem
Hydrothermal liquefaction of biomass slurries faces challenges in efficiently pumping and separating bio-oils from reaction solutions due to high temperatures and pressures, as well as the formation of emulsions and the need for effective carbon dioxide release.
Innovation Solution
The process involves maintaining a biomass slurry solution at temperatures above 300°C and pressures of at least 2000 psig, followed by cooling and depressurization to release carbon dioxide and form a bio-oil foam, which is then filtered and separated using a system with a heated reaction zone in continuous fluid communication with a flash cooling/depressurization zone and a foam/liquid separation system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If biomass slurry is pumped through process systems at high temperature and pressure, then hydrothermal liquefaction can proceed, but pumping efficiency decreases and equipment complexity increases
Solution Approach 1:
The patent changes the physical state parameters of the biomass slurry by heating it to supercritical conditions (above 374°C and 221 bar), transforming it from a pumpable liquid slurry into a supercritical fluid that flows more easily through the reaction system, thereby reducing pumping complexity while maintaining high productivity
Solution Approach 2:
The patent applies preliminary heating and pressurization to convert the biomass slurry into a supercritical state before it enters the reaction zone. This preliminary action eliminates the need for complex high-temperature pumping equipment by performing the phase transformation upstream, simplifying the overall system while preserving bio-oil production efficiency
2Productivity
If biomass slurry is processed at high temperature and pressure, then reaction efficiency improves, but separation of bio-oil from reaction solution becomes more difficult
Solution Approach 1:
The patent utilizes phase transition by rapidly cooling and depressurizing the reaction mixture after the hydrothermal liquefaction reaction. This causes the supercritical fluid to transition back to liquid phase, triggering spontaneous phase separation where bio-oil, water, and gases separate into distinct layers, making separation easy despite high reaction efficiency
Solution Approach 2:
The patent employs segmentation by allowing the reaction mixture to separate into multiple distinct phases (bio-oil phase, aqueous phase, gas phase, and solid residue) after cooling. This natural phase segmentation occurs in the separation vessel, automatically dividing the complex reaction mixture into separable components without requiring complex separation equipment
3Stability of the object's composition
If carbon dioxide is retained in solution at high pressure, then reaction conditions are maintained, but emulsion formation increases and complicates separation
Solution Approach 1:
The patent extracts carbon dioxide from the reaction mixture by depressurizing the system after the reaction. As pressure drops, dissolved CO2 comes out of solution and forms a separate gas phase, removing it from the liquid mixture and preventing emulsion formation while maintaining reaction stability during the high-pressure reaction phase
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 allows for efficient bio-oil production with a mass yield ranging from 25 to 40 wt% on a dry ash-free biomass basis, effectively overcoming the challenges of pumping and separation while minimizing emulsion formation and optimizing carbon dioxide release.
Implementation Method 1
depressurizing the solution to release carbon dioxide from the solution and form at least part of a bio-oil foam
Implementation Method 2
cooling the solution to a temperature of less than 150° C.; and depressurizing the solution to release carbon dioxide from the solution and form at least part of a bio-oil foam
Implementation Method 3
a heated biomass slurry reaction zone maintained above 300° C. and at least 2000 psig
Implementation Method 4
a flash cooling/depressurization zone maintained below 150° C. and about atmospheric pressure
Data Source
AI summary
Liquefaction processes are provided that can include: providing a biomass slurry solution having a temperature of at least 300° C. at a pressure of at least 2000 psig; cooling the solution to a temperature of less than 150° C.; and depressurizing the solution to release carbon dioxide from the solution and form at least part of a bio-oil foam. Liquefaction processes are also provided that can include: filtering the biomass slurry to remove particulates; and cooling and depressurizing the filtered solution to form the bio-oil foam. Liquefaction systems are provided that can include: a heated biomass slurry reaction zone maintained above 300° C. and at least 2000 psig and in continuous fluid communication with a flash cooling/depressurization zone maintained below 150° C. and between about 125 psig and about atmospheric pressure. Liquefaction systems are also provided that can include a foam/liquid separation system. Liquefaction process intermediate compositions are provided that can include a bio-oil foam phase separated from an aqueous biomass solids solution.