Microwave ashing for determination of inorganic content in Crude Oil

Microwave Ashing for Determination of Inorganic Content in Crude Oil

Ashing of crude oil samples provides fundamental information about the quality of the product such as the amount of particulate emission to expect upon combustion.

The typically low inorganic content of crude oils requires large samples which then require long times for ashing and create a significant amount of fumes and odours in the lab.

This process is particularly well suited to microwave ashing which is significantly faster than using a conventional muffle furnace, allows the use of large sample sizes and effectively minimises exposure of users to fumes and potentially harmful vapours.

Ash-forming material in crude oil

Knowledge of the amount of ash-forming material present in crude oil product can provide information about whether the product is suitable for the use in a specific application. Mineral content can result from oil or water-soluble metallic compounds that can have an adverse effect on the petroleum refining process and may be directly related to particulate emission. The ashing of crude oil samples is then a fundamental test to provide information about the quality of the product.

Ash content of crude oil is usually very low and as such it is important to work with enough oil in order for the sample to be representative of the crude oil being tested. Large sample volumes can be problematic as they require long ashing times and generate a lot of fumes. Traditional tools, like electric muffle furnaces, have their own limitations – long ashing times, slow cooling and high power consumption for example. The PYRO microwave ashing system offers a superior design with an extremely well ventilated muffle which speeds up oxidation and minimises exposure of users to potentially harmful chemicals.

Goal of ashing

The goal of ashing is complete destruction of the organic species to leave only the mineral content behind. This mineral material may either be weighed directly to determine ash % or may be digested for subsequent analysis by ICP-OES or ICP-MS. The process then requires complete oxidation of the carbon present and hence the air flow through the muffle becomes critical in order achieve a comprehensive ashing in a short time.

Traditional muffle furnaces are typically sealed to avoid the loss of hot air which would effectively cool the furnace. The movement of air inside these muffles is then quite limited which results in a slow oxidation and hence long ashing times.

Microwave ashing uses a silicon carbide plate which absorbs microwave energy very efficiently to allow extremely fast heating. The microwave cavity and muffle block of the PYRO are effectively aspirated using a venturi system which uses a powered fan to drive air flow through the muffle, simultaneously removing fumes and odours as well as dramatically increasing the speed of oxidation.

Fast and safe procedure

The Milestone PYRO microwave ashing system incorporates all of the benefits of a microwave system working with specialised fast heating/cooling crucibles which makes the ashing procedure fast, easy, effective and completely safe.

This application report compares data for ashing of crude oil samples and shows that the PYRO can achieve the performance of traditional muffle furnaces in a fraction of the time.

Recommended application reports:

  • ASTM D5630 Standard Test Method For Ash Content In Thermoplastics (High Throughput)
  • ASTM D5630 Standard Test Method For Ash Content In Thermoplastics (Ultra Fast)
  • Microwave Sulfated Ashing Procedure Of Pharmaceutical Samples
  • Test Method For Ash Content Determination In Crude Oil Sample
  • Microwave Ashing Procedure For Determination Of Inorganic Ash In Food Samples

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