ERG (Air Pollution Control) Ltd announces the sale of another V-texTM to a global pharmaceutical manufacturing site in Ireland. This gas scrubber joins more than twenty other V-texTM scrubbers and strippers currently operating successfully in the Irish pharmaceutical industry.

The production of drugs in sealed pressurised batch reactors presents a unique challenge for gas cleaning equipment, as the gas flowrate varies dramatically as the reactor is vented down. It is critical these off-gases are cleaned to high efficiency as they can be contaminated with noxious gases, aerosols and particulates. Unlike other traditional packed tower or venturi scrubbers, the V-texTM excels under these variable conditions.

As the diagram shows, re-circulated scrubbing liquor is injected into a cylindrical V-texTM chamber via a unique opposed-jet nozzle which creates a fine spray across the scrubber chamber. The pressurised off-gases are fed tangentially into the V-texTM creating a vortex. The liquor droplets pass rapidly through the vortex creating intense gas-liquid contact absorbing and neutralising the soluble contamination, and simultaneously capturing any entrained particulates and aerosols.

The extraordinary feature about the V-texTM is that as the gas flowrate varies the mass transfer efficiency remains constant, making the V-texTM a self-regulating absorption technology for variable gas flows.

This is because the path length the gas travels in the vortex remains constant, irrespective of the change in gas flowrate and the consequential change in residence time of the gas in the scrubbing chamber. It is this vortex path length together with the density of sprayed liquor which dominates and dictates the efficiency of removal of contamination. Therefore gas flowrate changes have minimal effect on performance. This is radically different to other scrubbers, which can usually only operate effectively over a narrow flowrate range, and makes the V-texTM uniquely suited for treating vent down gases from pressurised reactors.

Another benefit of the V-texTM scrubber is that it can operate with viscous scrubbing liquors without reduction in performance or risk of blockage. For example, there are V-texTM scrubbers operating efficiently in the pharmaceutical and chemical industries using 20% caustic solution as the scrubbing liquor, contaminated with up to 10% suspended solids. For batch operations when gas cleaning is only needed during venting down of reactors it makes sense to use a batch filled scrubber. The advantage of a batch filled V-texTM scrubber with its unique opposed-jet nozzle and empty chamber design is that it can operate reliably with high concentration liquors, so liquor change out and effluent disposal are minimised.

For this recent project in Ireland the GRP PED-rated V-texTM scrubber is lined with a PTFE derivative material which protects the vessel against corrosion from the cocktail of VOC contamination and the high levels of acidity present in the vent down gases.

ERG’s V-texTM product manager, Terry Dumbrell says “Pharmaceutical clients who use V-texTM scrubbers for the treatment of pressurised batch reactor off-gases are universally delighted with the technology. We think there is no other technology to match it for this type of application”.