Total Nitrogen Measurement: Online Nitrogen Analyzers for Petroleum Products
Total nitrogen measurement in refinery and petroleum product streams: chemiluminescence-based online nitrogen analyzers and integrated sulfur-nitrogen process systems.
Measurement methods: Chemiluminescence
What is total nitrogen and why is it measured?
Total nitrogen in petroleum products is the sum of nitrogen present as organic nitrogen compounds in a hydrocarbon stream. In refineries, nitrogen compounds can poison hydroprocessing and cracking catalysts and affect product quality, so knowing the nitrogen content of feed and product streams is important for protecting catalyst life and adjusting process conditions. Because laboratory analyses can take hours, online measurement allows a rapid response to changes.
Where is total nitrogen measured?
- Hydroprocessing and hydrocracker units: In feed and outlet streams.
- Product streams: In diesel, naphtha and other intermediate product lines.
- Quality monitoring together with sulfur: In samples taken from the same sample line.
How is total nitrogen measured?
In total nitrogen measurement, the sample is burned in a high-temperature furnace; nitrogen compounds are converted to nitric oxide (NO) and measured by a chemiluminescence detector: NO reacts with ozone and emits light, and the light intensity is proportional to the amount of nitrogen. Because sulfur is converted to SO₂ in the same combustion step, some combustion-based analyzers measure sulfur and nitrogen from the same sample, so two quality parameters can be monitored on one instrument. The system is designed to include sampling, conditioning, verification (validation) and recovery units.
Choosing a nitrogen analyzer
- Single- or dual-stream sample arrangement
- Low- or high-temperature sample conditions
- Hazardous area classification and cabinet requirement
- Spare kit and consumables plan (1- and 2-year kits)
Total nitrogen measurement with Tetra
Tetra supplies the PAC NSure (ANTEK) sulfur and nitrogen analyzer, and builds distillation and nitrogen analyzers, together with their sample systems, as complete single- or dual-stream systems. Installation, commissioning, calibration and spare parts support are provided in Türkiye by Tetra.
Frequently asked questions
What unit is total nitrogen in petroleum products expressed in?
Total nitrogen is generally reported in mg/kg by mass (ppm by weight). In product streams with very low nitrogen, the result may also be given on the order of µg/kg (ppb). In systems with volumetric sample injection, sample density is used to convert the result to a mass basis.
Which standard methods is total nitrogen measurement based on?
For trace nitrogen in liquid hydrocarbons, ASTM D4629, based on oxidative combustion and chemiluminescence detection, is widely used. For heavy samples with higher nitrogen content, combustion-based methods such as ASTM D5762 are applied. Online analyzer results are periodically compared with these laboratory methods.
What is the difference between total nitrogen and basic nitrogen?
Total nitrogen is the sum of all nitrogen compounds in the sample and is measured by the combustion-chemiluminescence method. Basic nitrogen is the part of these compounds that can be titrated with acid, and it matters separately in catalyst poisoning. The two parameters are measured by different methods and should not be substituted for each other.
How is a chemiluminescence nitrogen analyzer calibrated?
The analyzer is calibrated with standard solutions of known nitrogen content, spanning the measurement range. Changes in combustion conditions, sample injection volume and detector sensitivity can affect the result over time, so regular checks are made with verification standards. The furnace tube, ozone generator and drying components should be included in the maintenance plan.
Products measuring this parameter
Let's choose the right product together
Tell us about your application; we will recommend the right model and configuration for the measuring point, process conditions and regulations.