Reactor Discharge Steam Control for Lignocellulose Processing
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Solution Overview
Problem
Existing steam explosion processes for lignocellulose materials face challenges in controlling steam usage, maintaining particle size reduction, and reducing maintenance costs due to high wear in blow valves and discharge nozzles.
Innovation Solution
A method and system for processing biomass that decouples thermal treatment from steam explosion, allowing for improved control of steam usage and particle size reduction, while using a pressure sealing screw and a discharge nozzle to reduce wear and maintenance costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a blow valve is used for steam explosion discharge, then particle size reduction is achieved through impact and shear forces, but the valve experiences very high wear and requires frequent maintenance
Solution Approach 1:
The patent extracts the steam explosion function from the blow valve by introducing a separate expansion chamber. The blow valve only performs discharge function while the expansion chamber performs steam explosion function, eliminating the wear problem from the blow valve.
Solution Approach 2:
The discharge system is segmented into two independent components: a blow valve for pressure release and an expansion chamber for steam explosion. This segmentation allows each component to be optimized for its specific function, reducing wear on the blow valve.
2Temperature
If steam is added to the reactor for heating biomass to saturation temperature, then thermal treatment is achieved, but steam usage control becomes difficult and costs increase
Solution Approach 1:
The patent extracts the steam heating function from the main reactor by introducing a separate expansion chamber where steam is added after discharge. This allows independent control of steam quantity for thermal treatment without affecting the main reactor operation.
Solution Approach 2:
The biomass is pre-heated in the main reactor before discharge, and then additional steam is added in the expansion chamber for further thermal treatment. This preliminary heating action reduces the total steam required for the complete thermal treatment process.
3Shape
If pressure is rapidly decreased during discharge from high pressure to ambient, then steam expansion causes material defibration, but the blow valve is exposed to very high wear
Solution Approach 1:
The patent extracts the steam expansion and material defibration function from the blow valve by introducing a separate expansion chamber. The pressure drop occurs in the expansion chamber rather than the blow valve, eliminating wear on the valve while maintaining the desired material breakdown.
Solution Approach 2:
The expansion chamber acts as an intermediary between the high-pressure reactor and ambient environment. It mediates the pressure drop and steam expansion process, protecting the blow valve from direct exposure to harsh conditions while still achieving material defibration.
Data Source
AI summary
A system for processing lignocellulosic materials includes: a pressurization vessel configured to perform hydrothermal treatment of the lignocellulosic materials using saturated or superheated steam; a pressure sealing screw configured to continuously discharge hydrothermally treated lignocellulosic material from the pressurization vessel to a discharge chamber; a control valve configured to add steam to the discharge chamber for pressure control; and a discharge nozzle configured to discharge the lignocellulosic material and steam from the discharge chamber with expansion of steam. The control valve is configured to add the steam to the discharge chamber so as to control a pressure in the discharge chamber to different levels at varying flow rates of the lignocellulosic material and to thereby control a ratio of an amount of steam that escapes through the discharge nozzle to an amount of the lignocellulosic material discharged through the discharge nozzle.