Inert balls in reactor

What are the inert balls in a reactor? What are their functions? Where are they used?

Inert balls in reactors are spherical components that do not participate in the main reactions within the reactor (such as chemical reactions, catalytic reactions, etc.), have stable chemical properties, and possess high-temperature resistance, corrosion resistance, or certain thermal conductivity. Their core functions include: filling the gaps in the catalyst bed within the reactor to prevent excessive wear or pulverization of catalyst particles due to vibration and impact; evenly distributing reaction materials and heat to prevent uneven reactions caused by local material accumulation and to suppress local overheating, thereby enhancing the thermal safety of the reactor; in fixed-bed reactors, the proportion and position of inert balls can be adjusted to optimize fluid flow patterns (such as reducing channeling and short-circuiting), ensuring reaction efficiency and product quality. Inert balls are mainly used in the catalyst beds of fixed-bed reactors (mixed with or layered with catalysts), transition zones at the reactor’s inlet and outlet (protecting catalysts from direct gas flow erosion), and high-temperature reaction systems (such as catalytic cracking and ammonia synthesis reactors), serving as important auxiliary components for maintaining stable reactor operation and extending catalyst life.

What are the quality standards for testing inert ceramic balls?

The quality standards for inert ceramic balls should be formulated around the four core requirements of “chemical stability, physical properties, appearance and shape, and application compatibility”. Different industries (such as petrochemical, coal chemical, environmental catalysis, etc.) and application scenarios (such as high-temperature reactions, corrosive systems) will add specific indicators on this basis. The following are the general and key quality inspection standards, clearly listed by category:

1. Chemical Performance Standards(Core: Anti-corrosion, Non-reactivity)
2. Chemical Composition Requirements: The content of main components (such as alumina, silicon carbide, cordierite, etc.) must comply with product specifications, and the content of impurities (such as Fe₂O₃, Na₂O, K₂O, etc.) must be ≤ the specified limit (typically Fe₂O₃ ≤ 0.5%, Na₂O + K₂O ≤ 0.3%), to prevent impurities from undergoing side reactions with reaction materials or affecting the activity of the catalyst.
3. Corrosion Resistance: After being immersed in the designated reaction medium (such as acids, bases, organic solvents) at the specified temperature (such as 200 – 1000°C) for the specified time (such as 24 – 72 hours), the mass loss rate must be ≤ 0.5%, and there should be no obvious dissolved substances (detected by ICP or chemical titration).
4. Chemical Inertness: Under working conditions, it does not undergo chemical reactions with the main reaction materials and catalysts in the reactor, and there is no adsorption, catalysis or decomposition of materials (verified through simulation of reaction conditions).

1. Physical Performance Standards(Core: High Temperature Resistance, Wear Resistance, Mechanical Stability)
2. High Temperature Resistance:

The maximum operating temperature should match the reactor conditions (e.g., for ordinary inert ceramic balls ≥ 1200°C, high-temperature type ≥ 1600°C);

Thermal stability: After a “heating-cooling” cycle (e.g., from room temperature to 800°C for 2 hours, then rapid cooling to room temperature), there should be no cracking or peeling, and the volume change rate should be ≤ 0.2%.

2. Mechanical Strength:

Compressive strength: There are clear requirements based on different ball diameters (e.g., for φ10mm balls ≥ 80MPa, φ25mm balls ≥ 60MPa), and no obvious plastic deformation should occur during the test.

III. Appearance and Dimension Standards (Core: Adapt to Bed Layer, Avoid Fluid Skew Flow)

1. Appearance Quality:

The surface should be smooth, free of obvious cracks, depressions, missing corners, burrs, and visible impurity spots;

There should be no hollow or delamination (verified by tapping and listening or non-destructive testing);

2. Dimension Deviation:

The deviation of the ball diameter must meet the tolerance requirements (for example, when the nominal diameter is φ5-50mm, the deviation ≤ ±0.5mm);

Roundness: The difference between the maximum and minimum diameters of the same ball should be ≤ 0.3mm to ensure uniform bed layer gaps during filling.