MEA Triazine Dosing Calculator & Guidelines for H2S Scavenging

The reaction between MEA Triazine (hexahydro-1,3,5-tris(2-hydroxyethyl)-s-triazine) and hydrogen sulfide proceeds with a theoretical stoichiometry of 1 mole of triazine reacting with up to 3 moles of H2S. The molecular weight of MEA Triazine is approximately 219 g/mol, and the molecular weight of H2S is 34 g/mol. At 78% active concentration and a density of approximately 1.08 kg/L, one litre of MEA Triazine 78% contains roughly 0.84 kg of active triazine — corresponding to about 3.84 millimoles of triazine. Theoretically, this can neutralise up to 11.5 millimoles (0.39 g) of H2S. Working through the arithmetic, the theoretical minimum consumption is approximately 2.6 litres of MEA Triazine 78% per kilogram of H2S removed. However, in real-world applications, the full 1:3 stoichiometric ratio is rarely achieved because of incomplete gas-liquid contact, competing reactions with CO2 and organic acids, and kinetic limitations at lower temperatures.

In practice, operators typically apply an excess factor of 2x to 4x above the stoichiometric minimum. This translates to a practical consumption of approximately 3.2 litres of MEA Triazine 78% per kilogram of H2S removed under good contact conditions, rising to 5–10 litres per kilogram in less favourable systems. The key factors that increase chemical consumption beyond stoichiometric include: H2S concentration (higher concentrations improve reaction efficiency), gas or liquid flow rate (higher velocities reduce contact time), temperature (reaction kinetics slow below 15 degrees Celsius), contact time and mixing efficiency (static mixers and contact towers improve utilisation), and water cut in oil systems (water is needed as a reaction medium for gas-phase scavenging). A useful rule of thumb for budgeting: assume 3.2 L of MEA Triazine 78% per kg of H2S in well-designed continuous injection systems with adequate contact time, and 5–6 L/kg in direct pipeline injection without a contact vessel.

Continuous injection is the standard approach for ongoing H2S removal in pipelines, gas processing, and production facilities. A chemical metering pump delivers triazine at a controlled rate, typically proportional to the measured H2S load. The injection point should be upstream of a mixing device — a static mixer, venturi, or contact tower — to maximise gas-liquid contact. Batch treatment is used for treating contained volumes such as storage tanks, produced water holding tanks, and during well-testing operations. A calculated volume of triazine is added to the system, agitated or circulated, and allowed to react over a contact period of 30 minutes to several hours depending on H2S loading and temperature. Batch treatment typically requires a higher excess factor (3–4x stoichiometric) because contact efficiency is lower than in continuous systems. For continuous injection, the dosing rate in litres per hour can be calculated as: Dose (L/hr) = H2S load (kg/hr) multiplied by the consumption factor (L/kg). The H2S load is derived from the gas flow rate and H2S concentration. Our technical team can assist with dosing calculations for your specific operating conditions.

Effective monitoring is essential to ensure H2S is reduced to target levels without excessive chemical consumption. The most common monitoring methods are: Gastec detector tubes provide a quick, low-cost spot measurement of H2S in gas streams. They are widely used for field verification at wellheads and pipeline outlets. Online H2S analysers (electrochemical or tunable diode laser) provide continuous real-time measurement and can be integrated with dosing pump controls for automatic rate adjustment. Stain-tube methods (Draeger, Gastec) are used for liquid-phase H2S measurement in produced water and treated fluids. Best practice is to monitor H2S concentration at the outlet of the contact system and adjust the dosing rate to maintain the target H2S level with the minimum practical excess. Tracking chemical consumption per kilogram of H2S removed over time helps identify changes in system efficiency and optimise costs. If consumption rises above the expected range, check for changes in H2S loading, temperature drops, or equipment issues such as dosing pump malfunction or plugged injection quills.