Corrosion-Resistant Steel Reactors for Lactic Acid Production
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Solution Overview
Problem
Conventional reactor materials corrode when used in the production of biodegradable polylactides, leading to equipment failure, contamination of products with metal salts, and reduced economic efficiency due to increased maintenance and contamination issues.
Innovation Solution
Using steel reactors with specific compositions (20-30% Cr, 3-10% Ni, 0.1-5% Mo, 0-0.5% N, and 0-0.1% C) and optional alloying elements like Cu, Mn, Ti, W, or Si to resist corrosion and maintain high purity of biodegradable cyclic diesters and polymers like dilactide and polylactide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional reactor materials are used, then manufacturing cost is reduced, but corrosion resistance deteriorates leading to equipment failure and product contamination
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the steel material. The steel contains 20-30% Cr, 3-10% Ni, 0.1-5% Mo, 0-0.5% N, and 0-0.1% C, with optional alloying elements Cu, Mn, Ti, W, or Si at 0.1-8.0% by weight. This compositional parameter optimization provides both superior corrosion resistance against lactic acid and economic feasibility through controlled material selection.
Solution Approach 2:
The patent employs composite materials by creating a multi-phase steel structure containing both ferritic and austenitic phases. This dual-phase composite microstructure combines the corrosion resistance of ferritic phases with the ductility and structural stability of austenitic phases, achieving enhanced overall performance for reactor applications in lactic acid processing.
2Duration of action of stationary object
If conventional materials are used, then initial equipment cost is reduced, but service life deteriorates due to corrosion
Solution Approach 1:
The patent extends service life through parameter changes in material composition, specifying 20-30% Cr for enhanced passivation layer formation, 3-10% Ni for structural stability, and 0.1-5% Mo for pitting corrosion resistance. These compositional parameters ensure long-term durability in lactic acid environments while maintaining manufacturing feasibility.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating protective alloying elements in advance during material fabrication. The Cr, Ni, and Mo content is pre-configured to form protective passive films on the steel surface before contact with lactic acid, preventing corrosion attacks and extending equipment service life through proactive protection.
3Manufacturing precision
If conventional materials are used, then equipment cost is reduced, but product purity deteriorates due to metal salt contamination
Solution Approach 1:
The patent achieves high product purity through parameter changes in steel composition, specifically limiting carbon content to 0-0.1% and controlling alloy element ranges to minimize metal salt dissolution. The optimized Cr (20-30%), Ni (3-10%), and Mo (0.1-5%) content creates a stable, non-reactive surface that prevents contamination of lactic acid and downstream products.
4Reliability
If corrosion-resistant materials are used, then equipment reliability is improved, but maintenance cost increases
Solution Approach 1:
The patent reduces maintenance cost while maintaining high reliability through optimized parameter ranges in steel composition. The specific Cr (20-30%), Ni (3-10%), and Mo (0.1-5%) content provides sufficient corrosion resistance to minimize equipment failures and maintenance interventions, achieving cost-effective reliability through material science optimization rather than excessive material specification.
Data Source
Figure 1
AI summary
The present invention relates to a method for the production or purification of biodegradable, intramolecular cyclic esters of alpha-hydroxycarboxylic acids, biodegradable alpha-hydroxycarboxylic acids or oligopolymers or polymers thereof, and to biodegradable polyesters that can be produced from said compounds.