gas oil analysis

Introduction

Diesel fuel is one of the most widely used fuels in various industries and diesel engines, with its quality and composition having a direct impact on equipment performance, engine efficiency, and emission levels. Diesel fuel analysis is a process in which the physical and chemical properties of this fuel, including density, viscosity, sulfur content, boiling and pour points, and hydrocarbon composition, are examined. The purpose of this analysis is to evaluate the quality of diesel fuel, ensure its compliance with international standards, and optimize its use under different conditions. Conducting these tests helps guarantee engine performance, reduce emissions, and ensure efficient fuel consumption. This article explores various aspects of diesel fuel analysis and its significance in improving efficiency and minimizing environmental impacts.

It is worth noting that Kian Petroleum Company does not provide any services related to the supply or transportation of diesel fuel.

Diesel Fuel Analysis

Density at 15°C

The density at 15°C in diesel fuel analysis refers to the mass per unit volume of the fuel at the reference temperature of 15°C and is expressed in kilograms per cubic meter (kg/m³) or grams per cubic centimeter (g/cm³). The temperature of 15°C is chosen as the international standard for measuring the density of fuels.

The density of diesel fuel at 15°C should range between 820 and 860 kg/m³. This range indicates a proper balance between light and heavy hydrocarbons in the fuel. Density provides information about the quality of the fuel, the energy content per unit volume, and the efficiency and emission levels of the engine. Higher density may result in greater energy output but also increased emissions, while lower density could lead to reduced power and fuel efficiency.

Distilled Volume

The distilled volume in diesel fuel analysis indicates the percentage of fuel that evaporates at specific temperatures. This parameter provides detailed information about the hydrocarbon composition of the fuel and determines its quality, combustion performance, and compliance with diesel engine standards. By analyzing the distilled volume, the behavior of the fuel under different conditions can be assessed, and its composition can be optimized to improve efficiency, reduce emissions, and prevent deposit formation.

Reason for Selecting Specific Temperatures:

The temperature of 150°C represents the light components of the fuel, which affect quick engine startup and performance in cold conditions. The temperature of 300°C is used to analyze mid-range components that are responsible for the primary energy output of the fuel. The temperature of 375°C reflects the distillation of heavier components, which influence deposits, emissions, and long-term engine performance. These temperatures are chosen based on international standards to cover the complete range of hydrocarbons present in diesel fuel, allowing for a comprehensive evaluation of its behavior.

F.B.P (Final Boiling Point)

F.B.P, or Final Boiling Point, refers to the highest temperature at which the last distillable components of a fuel (such as diesel) are vaporized during the distillation process. This parameter is commonly measured in fuel distillation analysis and indicates the presence of heavier components in the fuel.

Sulfur Total

Sulfur Total represents the total sulfur content in diesel fuel, usually expressed in milligrams per kilogram (ppm) or as a mass percentage. This parameter reflects the fuel's quality and its impact on the environment and engine performance. High sulfur content can lead to the formation of pollutant gases like SO₂ during combustion, which contributes to air pollution and damages emission-reducing systems like catalytic filters. Modern standards allow only minimal sulfur levels in fuels to reduce emissions and improve the performance of diesel engines.

Viscosity Kinematic

In diesel fuel analysis, kinematic viscosity is a measure of a liquid's resistance to flow, indicating the rate at which it moves under the influence of gravity. It is calculated as the ratio of dynamic viscosity to the liquid's density and is typically expressed in square millimeters per second (mm²/s) or centistokes (cSt). Kinematic viscosity is highly significant in diesel fuel as it affects lubrication, fuel flow within the engine system, and combustion efficiency. Very low viscosity can lead to reduced lubrication, while high viscosity can slow fuel flow and decrease engine performance. This parameter is temperature-dependent and is usually measured to evaluate fuel performance under various environmental conditions.

Cloud Point

The cloud point is the temperature at which hydrocarbon fuels like diesel begin to form wax-like crystals (paraffin) that appear as cloudiness or "haze" in the fuel. This phenomenon typically occurs at low temperatures and depends on the paraffinic content of the fuel. The cloud point is an important indicator of fuel performance in cold weather, as temperatures below this point may cause the formed crystals to clog filters and reduce fuel flow in the engine system. Therefore, knowing the cloud point is essential for selecting the appropriate fuel for cold climatic conditions.

Pour Point

The pour point is the lowest temperature at which a liquid, such as diesel or lubricants, can still flow. Below this temperature, the liquid becomes so thick and viscous that it is no longer able to move. This property is crucial for assessing fuel performance in cold conditions, particularly in colder regions. The pour point helps in designing fuel delivery systems and preventing issues caused by fuel blockages at low temperatures.

Cetane Index

The Cetane Index is a measure used to estimate the combustion quality of diesel fuel without the need for complex laboratory testing. It is calculated using mathematical formulas based on the physical properties of the fuel, such as density and average boiling point. The Cetane Index indirectly indicates the fuel's ability to ignite quickly and efficiently in diesel engines and is typically used when direct measurement of the Cetane Number is not feasible.

In the analysis of high-quality diesel fuel, the Cetane Index should usually be above 45. Fuels with a lower Cetane Index may exhibit poorer performance in diesel engines, such as incomplete combustion or higher emissions. Generally, a Cetane Index above 50 is considered indicative of high-quality fuel.

Difference Between Cetane Index and Cetane Number

Both the Cetane Index and Cetane Number relate to the combustion quality of diesel fuel, but they are determined differently. The Cetane Number is measured through practical laboratory tests using a standard engine and provides a precise measure of the fuel's ignition quality. In contrast, the Cetane Index is a calculated estimate derived from the physical properties of the fuel and is less accurate than the Cetane Number. Thus, the Cetane Number is an experimental and laboratory-based metric, while the Cetane Index is an approximate and computational method.