One Refinery, One Life: The Energy Difference Between Liquefied Petroleum Gas and Associated Petroleum Gas

One Refinery, One Life: The Energy Difference Between Liquefied Petroleum Gas and Associated Petroleum Gas

Associated Petroleum Gas & Liquefied Petroleum Gas

In the world of petroleum, it's not just black liquid that flows. Born alongside crude oil are two seemingly similar yet fundamentally different gases—Liquefied Petroleum Gas (LPG) and Associated Petroleum Gas (APG).

Liquefied Petroleum Gas (LPG) and Associated Petroleum Gas (APG) share the same petroleum industrial origins, yet exhibit significant differences in formation mechanisms, composition structures, and application domains.

Understanding these distinctions aids in selecting more suitable gas sources for energy utilization, power generation, and clean fuel applications.

Source Differences: Same Origin, Different Paths

Though both originate from petroleum systems, LPG and associated gas emerge at distinct points in the industrial chain.

LPG primarily arises during refining or natural gas processing. When crude oil undergoes fractionation, cracking, or hydrocarbon removal, light hydrocarbons like propane and butane are separated. Compression liquefies these into storable, transportable fuel gas suitable for commercialization.

In contrast, associated petroleum gas is more primitive. Coexisting with crude oil in underground reservoirs, it is released during crude extraction. Its composition is primarily methane, with minor amounts of ethane, propane, and impurity gases. As the earliest encountered “natural gas form” in oilfields, it is often flared onsite or vented due to characteristics like dispersed distribution, significant pressure fluctuations, and high impurity levels. With the rise of clean energy concepts, an increasing number of oilfields are establishing associated gas recovery and power generation systems.

Differences in Chemical Composition and Properties: Composition Determines Character

Liquefied petroleum gas (LPG) is primarily composed of propane (C₃H₈) and butane (C₄H₁₀). Its heavier molecular structure yields high energy density, allowing it to easily liquefy under pressure at ambient temperatures. This property makes it exceptionally flexible for storage and transportation, making it an ideal fuel for household gas appliances, industrial boilers, and small generator sets. When ignited, it produces a stable flame with high calorific value and complete combustion—truly “gentle in nature yet powerful in effect.”

Associated petroleum gas, however, has a composition closer to natural gas, primarily consisting of methane (CH₄) supplemented by ethane, propane, and trace inert gases. It is lighter, disperses rapidly, and has a lower energy density, making it difficult to liquefy at ambient temperatures. It requires high-pressure or cryogenic storage. For this reason, associated gas is better suited for direct utilization at the extraction site—such as for power generation or gas injection recovery—rather than long-distance transportation.

It can be said that propane and butane endow liquefied petroleum gas (LPG) with “concentrated energy,” while methane gives associated gas its “light, clean” nature. Both can burn and produce light, yet they exhibit distinctly different characteristics in terms of temperature, density, and applications.

Liquefied Petroleum Gas: Flexible and Efficient Clean Energy

LPG's application in power generation is gaining increasing favor due to its “flexible, clean, and stable” characteristics.

First, it offers outstanding combustion performance. Primarily composed of propane and butane, LPG boasts high calorific value, complete combustion, and excellent ignition properties. It enables rapid engine startup and high thermal efficiency. Simultaneously, its emissions of carbon dioxide, nitrogen oxides, and particulate matter are significantly lower than diesel or heavy oil, making it a quintessential clean fuel.

Second, it offers convenient storage and transportation with flexible supply. LPG can be stored at ambient temperatures through pressurized liquefaction, offering high energy density and compact footprint. This makes it ideal for independent power supply in areas without natural gas pipelines. Whether in mountainous regions, islands, industrial parks, or temporary construction sites, rapid deployment is achievable via tanked storage systems.

More importantly, LPG power generation contributes to energy diversification and low-carbon transition, providing reliable support for energy systems.

Jiangsu Kelinyuan

Kelinyuan gas generator sets demonstrate significant advantages in system integration, including flexible design, efficient operation, and easy maintenance. When handling LPG with varying compositions, the combustion control system can be adjusted based on gas composition data. This significantly enhances combustion efficiency and power output while reducing emissions and extending equipment lifespan.

For instance, when propane content is high, nozzles and burners are adjusted to accommodate the high-calorific fuel, ensuring complete combustion and preventing waste. When butane content is high, air supply is increased to ensure thorough butane combustion, minimizing emissions of unburned hydrocarbons.

To address customer needs, our team conducted on-site verification of LPG power generation efficiency. Results demonstrate stable electricity generation exceeding 6 kWh per cubic meter of LPG, showcasing outstanding performance. This data aligns closely with our years of operational experience and experimental database results, fully validating our mature technical capabilities in LPG power system design, gas combustion control, and energy efficiency management. Leveraging extensive project experience and experimental validation, we provide efficient, reliable end-to-end LPG power generation solutions tailored to diverse gas source conditions and load requirements.