Triazine H₂S Scavenger: Direct Injection vs Contactor Tower

Direct injection sprays triazine H2S scavenger straight into the gas or liquid stream (via a quill, atomizer, fog nozzle or static mixer), relying on in-line contact time. A contactor tower routes sour gas up through a column of liquid triazine so the H2S dissolves and reacts. The tower gives much longer contact time and higher removal efficiency; direct injection is simpler and lower-CAPEX.

A contactor tower is more efficient — removal can reach roughly 80% of theoretical scavenger capacity because of the extended gas–liquid contact, so it consumes less chemical per unit of H2S removed. Direct injection is typically less efficient (often around 40%) because contact time is limited, meaning more chemical is used to hit the same outlet spec.

Use direct injection when you need a low-CAPEX, fast-to-deploy solution, have adequate line length/residence time for reaction, or are treating a pipeline or liquid stream. It is also preferred offshore or on skids where the size and weight of a contactor tower and its storage tanks are impractical.

Maximize contact by using proper atomization (quills, fog nozzles), a static mixer downstream of the injection point, correct injection location, and enough residence time before the next separation step. Matching the right triazine grade and injection rate to the H2S load also improves scavenging and avoids over-treatment.

Both work in towers. MEA triazine 78% is the high-active workhorse for many gas and liquid duties. MMA triazine 40% is favoured where its more soluble reaction by-products reduce solids/scaling in the tower and downstream — useful for continuous, long-run or higher-temperature service. See our MEA vs MMA comparison for selection guidance.

Often yes. Because a tower removes more H2S per litre of scavenger, chemical consumption (a major OPEX line) drops significantly versus direct injection at the same outlet spec — frequently offsetting the higher upfront equipment cost over time. The trade-off is footprint, weight and maintenance (solids management).