Buffer Function

Hydrogen consumption varies as hydrotreaters adjust feed rates, reactors cycle, or fuel cells modulate load. Without buffering, pressure swings force compressors or generators to start-stop frequently, wasting energy and shortening equipment life. Buffer vessels provide volume cushion that dampens these variations, storing gas during low demand and releasing during peaks.

Vessel Sizing

Capacity typically provides 10-30 minutes of average consumption at operating pressure. Larger volumes reduce compressor cycling more but cost additional capital and plot space. Horizontal or vertical configuration depends on site layout. Operating pressure matches distribution system, commonly 150-450 psig for refineries, up to 900 psig for some applications.

Material Requirements

Carbon steel works for most hydrogen service when properly selected to avoid hydrogen embrittlement. Material specifications follow API 941 guidelines. Killed, fine-grain steels resist cracking. Welding procedures control residual stress. Some high-pressure applications use chrome-moly alloys.

Applications

Refinery hydrogen distribution buffering multiple hydrotreating units, hydrogen plant outlet surge capacity, fuel cell system pressure regulation, hydrogenation reactor feed stabilization, and any hydrogen network with variable demand. Serves flow rates from 1,000 to 500,000 SCFH.

Control Integration

Pressure transmitters monitor vessel pressure controlling compressor operation. Start-stop setpoints reduce cycling while keeping pressure within acceptable range. Integration with hydrogen balance systems optimizes production versus consumption. Simple passive buffering needs no active control during normal operation.

System Benefits

Compressor runtime extends when starts reduce from hourly to every few hours or shifts. Energy costs drop as motors avoid startup surges. Pressure stability improves process control in downstream units. Maintenance intervals lengthen with less mechanical cycling.

Safety Considerations

Hydrogen service requires careful attention to material selection, welding quality, and leak prevention. Relief valves sized for worst-case scenarios including fire exposure. Installation follows spacing requirements for flammable gas storage. Gas detection monitors for leaks.

Design Standards

Construction per ASME Section VIII with materials meeting API 941 hydrogen service requirements. Welding per AWS with procedures qualified for hydrogen. Hydrostatic testing validates integrity. Non-destructive examination per code requirements.

Installation

Vessels mount on foundation or structural supports. Piping design minimizes pressure drop. Isolation valves allow maintenance without system shutdown. Proper grounding and bonding throughout. Installation meets electrical area classification for hydrogen.

ERGIL hydrogen buffer vessels stabilize distribution pressure while cutting compressor cycling and energy costs in refinery and industrial hydrogen systems.