HCl Adiabatic Absorption System

HCl Adiabatic Absorption System

Efficient Conversion of HCl Gas into Hydrochloric Acid

The HCl Adiabatic Absorption System is a specialized process unit designed to economically absorb hydrogen chloride (HCl) gas into water, producing hydrochloric acid solutions of 30–31% concentration under normal operating conditions.

This system is widely adopted where HCl gas is generated as a by-product and direct venting is prohibited due to environmental and safety regulations.

Unlike isothermal systems, adiabatic absorption operates without external heat input, relying on controlled heat generation within the absorption column for efficient mass transfer.

Process Working Principle

• HCl gas enters the absorption column from the bottom
• Fresh water is sprayed from the top of the column
• Gas and liquid flow counter-currently through multiple packed sections
• The absorption reaction is exothermic
• Heat generated causes approximately 30% of water to vaporize
• Water vapor and non-condensables rise to the column head
• A top condenser recovers vapors and returns condensate
• A bottom cooler dissipates heat before acid storage
• Hydrochloric acid is collected at the bottom at 45–50°C

For stable operation, gas loading should not fall below 50% of design capacity.

Key System Characteristics

• Adiabatic operation (no external heating)
• High absorption efficiency
• Continuous operation capability
• Minimal utility consumption
• Excellent environmental compliance
• Robust performance with mixed gas streams (air, moisture, non-condensables)

Salient Features

• Production of 30–31% hydrochloric acid
• Packed column design for high gas–liquid contact
• Efficient heat removal using condenser and cooler
• Handles air, water vapor, and non-condensable gases
• Corrosion-resistant construction
• Low operating and maintenance cost
• Safe containment of hazardous HCl gas
• Suitable for pilot and industrial scale

Construction & Materials

• Borosilicate Glass 3.3 (wetted parts)
• PTFE seals and gaskets
• High-efficiency structured or random packing
• Corrosion-resistant support structure
• Glass condenser and acid cooler
• Flanged connections for easy maintenance

Technical Specifications

Unit Model	Packed Column Size	Condenser HTA (m²)	HCl Gas Capacity
HCL3	80 mm × 3 m	0.35 × 2	10 kg/hr
HCL4	100 mm × 4 m	0.5 × 2	20 kg/hr
HCL6	150 mm × 4 m	1.5 × 2	60 kg/hr
HCL9	225 mm × 4.5 m	2.5 × 2	150 kg/hr
HCL12	300 mm × 4.5 m	4.0 × 2	300 kg/hr