Sizing Liquid Ring H2 Compressor Recycle Valve ·

Table of Contents

Problem background #

A water liquid ring compressor has arrived to process \(\sim 1100 \ \text{Nm}^3\text{/hr} \ \text{H}_2\). The problem is that its recycle valve is manual & during startup or shutdown of a plant operator has to be in close proximity to this compressor doing the manual labour. Production of \(\text{H}_2\) is summarised below:

stateDiagram-v2 Electrolyser --> VentValve VentValve --> Cooler Cooler --> Condensate : gravity flow Cooler --> PCV_alve% PCV_alve% --> Compressor : long piping Compressor --> BufferTank : 400mbarG BufferTank --> RecycleV_alve% RecycleV_alve% --> Compressor

Electrolyser main pressure control valve is placed after cooler to reduce vapour load (condensate is removed beforehand)
Valve receives low temperature but higher density gas thus lesser volumetric flowrate is processed by valve
Will reduce CAPEX of percentage valve

Calculations via SMath #

Source file is uploaded hereCalculation Results

Sanity check via vendor #

These are very close results we achieved using Blackmonk Engineering Ltd. calculator

Practical considerations #

Vendor brochure must be studied to get valve’s %Opening range that covers our needs. An Equal% valve was selected henceforth
During calculations a test for gas choke flow must be carried out
During calculations gas compressibility factor must be accounted for. Its negligible for \(\text{H}_2\) but significant for \(\text{Cl}_2\)
Warning! The ring (or the piston) in this compressor is made of water. Too much low inlet pressure can cause vaporisation of this ring within compressor leading to severe vibration & metal damage. Thus recycle valve rating must be done at different but permissible suction pressures