How can we remove rust and maintain a hydrogenation reactor? How can we extend its service life?

How do you remove rust and maintain a hydrogenation reactor? How can you extend its service life?

A hydrogenation reactor is a commonly used reaction vessel in chemical production. With prolonged use, its surface will inevitably suffer some degree of wear and tear. Whenever the surface is corroded by certain chemicals, it is typically coated with an anti-corrosion layer. Therefore, after use, we must also take good care of this anti-corrosion layer.

In addition to factors such as coating type, coating quality, and construction environment, the service life of anti-corrosion coatings for hydrogenation reactors is influenced by surface treatment, accounting for approximately 50%. Therefore, it is essential to strictly adhere to the specifications for anti-corrosion coatings on hydrogenation reactor surfaces and continuously explore and summarize effective surface treatment methods. Among these, there are four primary treatment methods:

Method 1: Acid Pickling

Generally, chemical and electrolytic methods are used for pickling. Chemical pickling is primarily employed for corrosion prevention and can remove scale, rust, and old coatings. It is sometimes also used as a post-processing step following sandblasting to remove rust. Although chemical cleaning can produce a clean and rough surface, the resulting anchor profile is relatively shallow, making it prone to environmental contamination.

Method 2: Rust Removal by Spraying (or Blasting)

Blasting (or polishing) rust removal involves a high-power motor driving blasting (or polishing) blades to rotate at high speed, causing abrasive materials such as steel grit, steel shot, wire segments, and minerals to be blasted (or polished) onto the surface of the hydrogenation reactor under the action of centrifugal force. This process not only removes rust, oxides, and dirt but also achieves the uniform roughness required for the reactor surface through the intense impact and friction of the abrasive materials.

Method 3: Cleaning

Solvents and emulsifiers are used to clean steel surfaces, removing oil, grease, dust, lubricants, and similar organic substances. However, they cannot remove rust, scale, flux, or other such contaminants. Therefore, on the steel surfaces of hydrogenation reactors, they serve only as an auxiliary tool in corrosion prevention production.

Method 4: Rust Removal with Tools

The steel surfaces of reaction vessels are primarily polished using tools such as wire brushes to remove loose or flaking oxide scales, rust, welding slag, and other contaminants. Manual tools can achieve a Sa2-level surface preparation, while power tools can reach the Sa3 level. However, if the steel surface of a hydrogenation reactor is covered with firmly adhered oxide scales, the cleaning effect of these tools will be unsatisfactory and will fail to meet the required anchor profile depth for corrosion protection work.

When using a hydrogenation reactor, there are generally specific requirements for the installation environment, such as ventilation and lighting conditions. Therefore, hydrogenation reactors must be installed and used in designated locations. Tips for extending the service life of a hydrogenation reactor include:

1. When the hydrogenation reactor comes into contact with different media, it is essential to first determine whether the medium will corrode the main material. For rapid reactions that generate large amounts of gas or involve flammable and explosive chemical reactions at high temperatures, as well as for media under ultra-high pressure, ultra-high temperature, or containing fluoride ions, chloride ions, and other such substances, custom designs are required. Such media can cause severe corrosion of stainless steel.

2. When loading the reaction medium, do not exceed 2/3 of the liquid level in the laboratory reactor.

3. If an abnormal sound is detected inside the isolation sleeve during operation, shut down the machine to relieve pressure and check whether there are any abnormalities in the stirring system. Regularly inspect the swing of the stirring shaft. If the swing is excessive, immediately replace the bearing or sliding sleeve.

4. Each time the device is powered on, all buttons will be in their initial state, so users need to develop a good habit: After each use, turn the knob back to a small position to prevent excessive current surges when the device is next turned on, which could cause significant damage to the controller.

5. Under no circumstances is it permitted to disassemble equipment under pressure during work or at the end of work. It is strictly forbidden to operate the kettle beyond its specified pressure and temperature limits.

6. After the controller’s power is turned on, even if switches for heating, stirring, and other functions remain off, the output terminals on the rear panel of the controller will still be energized. Therefore, during operation, you must not unplug or touch any connectors.

7. Once the final reaction temperature has been determined, the temperature setpoint must not be changed during the heating process to avoid significant overshoot in temperature.

8. When cleaning, pay special attention to prevent water or other liquids from entering the heating furnace, as this could damage the furnace’s wiring. If you are using a water jacket to heat thermal oil, be sure not to add water or any other liquid into the water jacket’s thermal oil, and regularly check the oil level in the thermal oil.

9. When the hydrogenation reactor is not used for an extended period, clean both the inside and outside of the reactor with a soft cloth, ensuring that there is no water or other substances present. Store the reactor in a clean, dry, and non-corrosive environment.