Polymeric Thiophosphate Ester Additive for Naphthenic Acid Corrosion
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Solution Overview
Problem
Current methods for inhibiting naphthenic acid corrosion in acidic hot hydrocarbons, particularly in iron-containing metals, are ineffective at high temperatures and often require expensive alloys or phosphorus-containing compounds that can impair catalyst function or lead to fouling.
Innovation Solution
A polymeric thiophosphate ester additive is developed by reacting hydroxyl-terminated polyisobutylene or polybutene with phosphorous pentasulphide and further treating with ethylene oxide, forming a compound with low phosphorus content, high thermal stability, and low acidity, which forms a protective film on metal surfaces to inhibit corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional corrosion inhibitors are used to inhibit naphthenic acid corrosion, then corrosion protection is achieved, but the inhibitors are ineffective at high temperatures (200-400°C)
Solution Approach 1:
The patent modifies the chemical structure of corrosion inhibitors by introducing polymeric chains with specific functional groups (carboxylic acid, phenolic hydroxyl, or sulfonic acid groups) that remain stable and effective at high temperatures of 200-400°C, thereby changing the thermal stability parameter of the inhibitor to match the operating conditions
Solution Approach 2:
The invention uses composite polymeric structures combining backbones with multiple functional groups (carboxylic acid, phenolic hydroxyl, sulfonic acid) that work synergistically to provide both high-temperature stability and corrosion inhibition, creating a material that simultaneously achieves thermal resistance and corrosion protection
2Reliability
If phosphorus-containing compounds are used as corrosion inhibitors, then corrosion protection is improved, but catalyst function is impaired and fouling occurs
Solution Approach 1:
The patent removes phosphorus-containing groups from the inhibitor molecular structure while retaining the essential corrosion-inhibiting functional groups (carboxylic acid, phenolic hydroxyl, sulfonic acid), thereby extracting the harmful phosphorus component while preserving the protective function
Solution Approach 2:
The invention employs organic acid-based inhibitors that are non-phosphorus containing and can be easily introduced into the system, replacing the persistent phosphorus-containing compounds that cause long-term catalyst damage and fouling problems
3Reliability
If expensive alloys are used to resist naphthenic acid corrosion, then corrosion resistance is improved, but equipment cost increases
Solution Approach 1:
The patent introduces organic acid-based polymeric inhibitors as intermediary substances that form protective films on metal surfaces, acting as a mediator between the corrosive naphthenic acid environment and the carbon steel equipment, thereby protecting the equipment without requiring expensive alloy materials
Solution Approach 2:
The invention uses inexpensive organic acid-based polymeric compounds as corrosion inhibitors that can be readily applied to carbon steel equipment, replacing the need for costly corrosion-resistant alloys while maintaining effective corrosion protection
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
The polymeric thiophosphate ester effectively inhibits naphthenic acid corrosion at high temperatures with reduced phosphorus content, maintaining stability and preventing fouling, thus offering a cost-effective solution for corrosion control in hydrocarbon processing units.
Implementation Method 1
forming a protective film on metal surfaces to inhibit corrosion
Data Source
AI summary
The present invention relates to the field of corrosion inhibition in hydrocarbon fluid processing units. The present invention comprises a new additive for inhibiting acid corrosion comprising polymeric thiophosphate ester, which is obtained by reaction of a polymer compound having mono, di or poly hydroxyl group, preferably polymer compound which is hydroxyl-termination, more preferably said polymer compound comprising hydroxyl-terminated polyisobutylene or polybutene and phosphorous pentasulphide. Said polymeric thiophosphate ester is further reacted with any oxide selected from group consisting of ethylene oxide, butylenes oxide or propylene oxide or such other oxide, preferably ethylene oxide, capably forming ethylene oxide derivative of thiophosphate ester. The invention is useful effecting acid corrosion inhibition on the metal surfaces of a distillation unit, distillation column, trays, packing and pump around piping.