Determination of Trace Water in Liquid Hydrocarbons

Overview

  Liquid hydrocarbons are important chemical raw materials widely used in the production and processing of chemical products such as ethylene, propylene and liquefied petroleum gas. The trace water contained in them will directly affect product quality and the safe operation of production equipment, and may also lead to side reactions in subsequent chemical reactions and catalyst deactivation. Accurate determination of trace water in liquid hydrocarbons is a key link in quality control and safety management of chemical production, and flash vaporization sampling technology is the core pretreatment method to achieve accurate determination of trace water in liquid hydrocarbons.

Experimental Objective

  By determining the trace water content in liquid hydrocarbons, we can accurately judge whether liquid hydrocarbon raw materials meet the purity requirements of the production process, and avoid production problems such as equipment corrosion and reaction inefficiency caused by excessive moisture content. This determination is carried out in accordance with GB/T3727-2003 Determination of Trace Water in Industrial Ethylene and Propylene. The SH201 Flash Vaporization Sampler is specially designed for the pretreatment of liquid hydrocarbon samples, which is perfectly compatible with this national standard method. It can convert liquid hydrocarbons into gaseous samples with isocomposition, constant temperature and constant pressure, providing accurate pretreatment guarantee for trace water determination.

Experimental Samples: Liquid hydrocarbons (ethylene/propylene/liquefied petroleum gas, etc.)

Experimental Instruments

1. SH201 Flash Vaporization Sampler

2. Auxiliary equipment: Karl Fischer Moisture Titrator/Dew Point Meter, sampling cylinder, stainless steel tube/polytetrafluoroethylene tube, analytical balance, etc.

Operating Procedures

1. Place the SH201 Flash Vaporization Sampler in a fume hood, connect the vent port and injection port, and connect the injection port to a Karl Fischer Moisture Titrator/Dew Point Meter with the pipelines as short as possible.

2. Connect the downward outlet of the sampling cylinder to the instrument port and tighten it, fully open the cylinder outlet valve to ensure that the liquid sample directly enters the instrument. At the same time, connect the instrument power supply and ensure good earthing of the ground wire.

3. Turn on the instrument, enter the preheating interface to set the vaporization temperature (≥60℃). After 15 minutes of preheating and temperature constant, adjust the flow rate (1.5-2 L/min for routine analysis) and injection volume (5-15 L, the lower the moisture content, the larger the injection volume) on the parameter setting interface.

4. After the Karl Fischer Moisture Titrator/Dew Point Meter reaches the end point, press the instrument's injection key to start the injection and determination. The instrument will automatically control the flow rate and record the cumulative injection volume.

5. When the set injection volume is reached, the instrument will automatically switch to the vent state. The Karl Fischer Moisture Titrator/Dew Point Meter will complete the determination and display the water content. Input the actual injection volume to calculate the final moisture concentration, and the test report can be printed directly.

6. After the completion of one set of determinations, the next set of parallel determinations can be started directly without turning off the instrument. 5 parallel results are required for routine determinations.

Data Analysis and Result Evaluation

  The trace water content in standard liquid hydrocarbon samples was determined by pretreatment with the SH201 Flash Vaporization Sampler combined with determination by a Karl Fischer Moisture Titrator. The instrument achieves isocompositional vaporization during the vaporization process, without water adsorption, freezing or concentration deviation. The repeatability error of the determination results meets the requirements of the national standard, and the basic error is controlled within ±5%. The measured value of trace water content accurately reflects the actual moisture content of liquid hydrocarbons, which can provide reliable and accurate data support for the quality judgment of liquid hydrocarbon raw materials in chemical production.