Vanconol^®RF Series Refinery Corrosion Inhibitors Recommended Solutions

(Tianjin Hi-Perferal Advanced Materials Co., Ltd.)

Abstract

Petroleum refining systems serve as the core downstream segment of the oil industry, primarily responsible for converting crude oil from upstream into qualified products such as gasoline, diesel, and lubricating oil through a series of processing steps. These processes include atmospheric/vacuum distillation, fluid catalytic cracking, hydrocracking/hydrotreating, reforming, coking, desulfurization/denitrification, sour water stripping, and other processing units. These systems operate under high-temperature, high-pressure corrosive media environments, particularly in delayed coking and hydrocracking processes where they are susceptible to H₂S-HCl-H₂O corrosion. This leads to thinning of equipment and pipeline walls, valve seal failure, and weld cracking, thereby increasing maintenance costs and the risk of unplanned shutdowns. The Vanconol^®RF refinery corrosion inhibitor series utilizes imidazoline-based active agents with efficient adsorption and multi-component synergistic formulation design to achieve high corrosion inhibition efficiency, good film-forming properties, and stability under various operating conditions.

This recommended solution aims to provide a detailed introduction to the Vanconol®RF refinery corrosion inhibitors from the perspectives of technical mechanism, performance indicators, application scenarios, field verification, and dosing optimization. It offers a compliant, efficient, stable, and implementable integrated solution for corrosion control in low-temperature sections of refining units.

1 Introduction

Corrosion in petroleum refining systems primarily results from the hydrolysis of chlorides present in crude oil (such as NaCl, CaCl₂, MgCl₂, etc.) under high-temperature conditions, generating hydrochloric acid that reacts with metallic components, causing corrosion. Simultaneously, sulfur corrosion and hydrochloric acid corrosion exhibit a synergistic effect, further attacking the equipment metal. Specifically, hydrogen sulfide first reacts with metallic iron to form a fragile and non-dense iron sulfide film, which hydrochloric acid then destroys, releasing hydrogen sulfide and creating a corrosion cycle. Subsequently, hydrochloric acid directly attacks metallic iron, forming water-soluble ferrous chloride, leaving the metal surface continuously exposed and corroded.

As crude oil quality deteriorates with increasing sulfur and acid content, refining units operate under prolonged exposure to high temperature, high pressure, high flow rates, and aggressive corrosive media, presenting significant safety risks such as equipment corrosion perforation and unplanned shutdowns. Carbon steel-based equipment and processes are particularly prone to pitting, uniform corrosion, and under-deposit corrosion. To ensure safe, stable, long-term, full-load, and optimized operation of refining systems, adding effective corrosion inhibitors has become one of the practical solutions to this issue.

The Vanconol®RF series refinery corrosion inhibitors are designed in accordance with standards Q/SHCG110-2017 and Q/SHCG109-2017. They are suitable for overhead systems of atmospheric distillation columns, primary distillation towers, and vacuum distillation towers, as well as low-temperature overhead systems of delayed coking units, fractionators and strippers in hydrogenation units.

2 Vanconol®RF Series Refinery Corrosion Inhibitors Introduction

2.1 Mechanism of Action

The products utilize imidazoline-type corrosion inhibitors as the core active agent. The nitrogen atom on the imidazoline ring possesses strong lone-pair electrons, enabling the formation of stable coordination bonds with metal atoms. Meanwhile, the long-chain alkyl groups in the molecule create a dense hydrophobic protective layer on the metal surface. This unique molecular structure design provides stronger adsorption and film-forming ability, allowing rapid adsorption and self-assembly into a high-density protective film that effectively blocks corrosive media from contacting the metal substrate.

The product employs multi-component synergistic compounding technology to enhance the density of the adsorbed film through the combined action of various active components while achieving comprehensive inhibition of the corrosion process:

Anodic inhibition: Active components form a protective film on anodic sites, inhibiting the anodic dissolution of metal.

Cathodic inhibition: Synergistic components form insoluble deposits on cathodic sites, suppressing the cathodic hydrogen evolution reaction.

Passive film formation: Multi-active components work synergistically to promote the formation of a stable passive film on the metal surface, significantly enhancing protection durability.

Oxygen reduction inhibition: The introduction of surface-active components facilitates uniform spreading of active ingredients on the metal surface, forming a complete coverage layer that effectively suppresses the oxygen reduction process.

2.2 Key Parameters

Table 1 Typical Parameters of Vanconol®RF Series Corrosion Inhibitors

Category	Product Model	Appearance	Density (20°C) (kg/m3)	Kinematic Viscosity (40°C) (mm2/s)	Pour Point (°C)	pH Value (10% solution)	Solubility	Emulsion Tendency
Water-soluble	RF-401	Yellow to yellow-brown uniform liquid	1000.9	2.55	< -22	8.6	Miscible with water in any ratio	None
	RF-401N	Yellow uniform liquid	1000.9	9.17	< -30	11.9	Miscible with water in any ratio	None
	RF-401W	Brown uniform liquid	1004.8	41	< -22	6.8	Miscible with water in any ratio	None
	RF-402	Yellow to yellow-brown transparent uniform liquid	954.6	4.46	< -23	4.9	Miscible with water in any ratio	None
	RF-402W	Brown uniform liquid	989.6	≤80	≤-20	8.49	Miscible with water in any ratio	None
Oil-soluble	RF-403	Yellow uniform liquid	988.8	10.18	< -30	–	Miscible with straight-run gasoline in any ratio	–
	RF-403W	Brown uniform liquid	989.9	39.2	< -30	–	Miscible with straight-run gasoline in any ratio	–

2.3 Typical Application Scenario Performance Description

Table 2 Typical Application Scenario Suitability

Product Model	Typical Application Scenario	Product Application Features
RF-401N	Neutralizing corrosion inhibitor for overhead systems of atmospheric distillation columns, primary distillation towers, and vacuum distillation towers	Fast film formation, low dosage, high corrosion inhibition efficiency
RF-401	Low-temperature water-soluble corrosion inhibitor for overhead systems of fractionators and strippers in delayed coking and hydrogenation units	Fast film formation, low dosage, high corrosion inhibition efficiency
RF-401W
RF-402		Dense and robust film formation, low dosage, high corrosion inhibition efficiency
RF-402W
RF-403	Low-temperature oil-soluble corrosion inhibitor for overhead systems of fractionators and strippers in delayed coking and hydrogenation units	Robust film formation, low dosage, high corrosion inhibition efficiency
RF-403W

Note: The static corrosion inhibition evaluation method for RF-401N follows the standard Q/SHCG109-2017 “Technical Requirements for Neutralizing Corrosion Inhibitors for Crude Oil Distillation Units”. The evaluation methods for other corrosion inhibitors follow the standard Q/SHCG110-2017 “Technical Requirements for Low-Temperature Corrosion Inhibitors for Delayed Coking and Hydrogenation Units”.

3 Field Application Case

Case Background: A refinery experienced excessive salt content after electrical desalting and dewatering due to poor crude oil quality, leading to elevated HCl levels during subsequent atmospheric/vacuum distillation. The monitored Fe ion concentration exceeded 3 mg/L.

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