Vanconol^®RF Series Recommended Corrosion Inhibitor Solutions for Refining Processes

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

Abstract

Petroleum refining systems represent the core downstream sector of the oil industry, responsible for converting crude oil into finished products such as gasoline, diesel, and lubricants through a series of processing steps. These systems include atmospheric/vacuum distillation, fluid catalytic cracking, hydrocracking/hydrotreating, reforming, coking, desulfurization/denitrification, and sour water stripping. Under high-temperature, high-pressure corrosive environments, especially during delayed coking and hydrocracking, equipment is susceptible to H₂S-HCl-H₂O corrosion, leading to wall thinning, valve seal failure, weld cracking, increased maintenance costs, and unplanned shutdowns. The Vanconol^®RF series of refining corrosion inhibitors employs imidazoline-based active agents with efficient adsorption and multi-component synergistic formulation design, delivering high corrosion inhibition efficiency, good film-forming properties, and stability under varying operating conditions.

This recommended solution aims to provide a comprehensive introduction to the Vanconol®RF series of refining corrosion inhibitors, covering technical mechanism, performance indicators, application scenarios, field validation, and dosing optimization. It offers a compliant, efficient, stable, and implementable integrated solution for low-temperature corrosion control in refining facilities.

1 Introduction

Corrosion in petroleum refining systems primarily results from the hydrolysis of chlorides present in crude oil (e.g., NaCl, CaCl₂, MgCl₂) at high temperatures, producing hydrochloric acid that reacts with metallic components. Simultaneously, sulfur corrosion and hydrochloric acid corrosion act synergistically: hydrogen sulfide reacts with iron to form a fragile, non-protective ferrous sulfide film, which is then destroyed by hydrochloric acid, releasing hydrogen sulfide again and creating a corrosive cycle. The hydrochloric acid directly attacks the metal, forming water-soluble ferrous chloride, leaving the metal surface continuously exposed.

As crude oil quality deteriorates with higher sulfur and acid content, refining units operate under prolonged exposure to high temperature, high pressure, high flow rates, and aggressive corrosive media, posing significant safety risks such as equipment perforation and unplanned shutdowns. Components made primarily of carbon steel are particularly susceptible to pitting, uniform corrosion, and under-deposit corrosion. To ensure safe, stable, long-term, full-capacity, and optimized operation of refining systems, the addition of effective corrosion inhibitors has become a viable solution.

The Vanconol®RF series of refining corrosion inhibitors is designed in accordance with Q/SHCG110-2017 and Q/SHCG109-2017 standards, and is suitable for use in the overhead systems of atmospheric towers, primary towers, and vacuum towers, as well as in low-temperature environments such as delayed coker fractionators and hydroprocessing unit stripper overhead systems.

2 Vanconol®RF Series Refining Corrosion Inhibitors Introduction

2.1 Mechanism of Action

The product uses imidazoline-based corrosion inhibitors as the core active agent. The nitrogen atom on the imidazoline ring possesses strong lone-pair electrons, enabling stable coordination with metal atoms. Additionally, the long-chain alkyl groups in the molecule form a dense hydrophobic protective layer on the metal surface. This unique molecular structure design provides enhanced adsorption and film-forming capability, allowing rapid adsorption and self-assembly into a high-density protective film that effectively isolates the metal substrate from corrosive media.

The product employs a multi-component synergistic compounding technology, leveraging the synergy of various active components to enhance the density of the inhibitor adsorption film while comprehensively suppressing the corrosion process:

Anodic inhibition: The active component forms a protective film on the anodic region, inhibiting the anodic dissolution process of the metal;

Cathodic inhibition: The synergistic component forms an insoluble deposit on the cathodic region, inhibiting the cathodic hydrogen evolution reaction;

Passivation film formation: The multi-active components work together to promote the formation of a stable passivation film on the metal surface, significantly enhancing protective durability;

Oxygen reduction inhibition: The introduction of surface-active agents helps the active components uniformly spread on the metal surface, forming a complete coverage layer that effectively inhibits the oxygen reduction process.

2.2 Key Parameters

Table 1 Typical Parameter Information for Vanconol®RF Series Corrosion Inhibitors

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

2.3 Performance Description for Typical Application Scenarios

Table 2 Applicability for Typical Application Scenarios

Product Model	Typical Application Scenario	Product Application Features
RF-401N	Neutralizing corrosion inhibitor for overhead systems of atmospheric towers, primary towers, and vacuum towers	Rapid film formation, low dosage, high corrosion inhibition efficiency
RF-401	Water-soluble low-temperature corrosion inhibitor for overhead systems of fractionators and strippers in delayed coking and hydroprocessing units	Rapid 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	Oil-soluble low-temperature corrosion inhibitor for overhead systems of fractionators and strippers in delayed coking and hydroprocessing units	Robust film formation, low dosage, high corrosion inhibition efficiency
RF-403W

Note: Static corrosion inhibition evaluation for RF-401N follows Q/SHCG109-2017 “Technical Requirements for Neutralizing Corrosion Inhibitors in Crude Oil Distillation Units”. Evaluation for other corrosion inhibitors follows Q/SHCG110-2017 “Technical Requirements for Low-Temperature Corrosion Inhibitors in Delayed Coking and Hydroprocessing Units”.

3 Field Application Case

Background: A refinery experienced salt content exceeding limits after electrical desalting and dehydration due to poor crude oil quality, leading to elevated HCl concentration during atmospheric/vacuum distillation, with Fe ion levels exceeding 3 mg/L.

Product Selection: Corrosion inhibitor performance was evaluated per Q/SHCG110-2017 “Technical Requirements for Low-Temperature Corrosion Inhibitors in Delayed Coking and Hydroprocessing Units” by observing corrosion of 20# carbon steel substrate in field water. Results are shown below:

<table border="1" cellpadding="3" cellspacing="0" style="border-collapse: