Types of Vapor Recovery Units

In the oil and gas industry, Vapor Recovery Units (VRUs) play a vital role in capturing hydrocarbon vapors that would otherwise be lost. While both rotary screw and reciprocating compressors are used, the choice of VRU technology depends heavily on site-specific factors, especially vapor flow rates and pressure stability.

1. Rotary Screw VRUs

Rotary screw VRUs are ideal for operations where vapor volumes fluctuate significantly. These units are well-suited for capturing vapors from production tanks or gathering systems due to their efficient capacity control and ability to adapt to changing flow demands.

Key Features:

• Continuous Compression: Rotary screw VRUs excel with rapid speed adjustments, allowing precise control over vapor volumes, including down to zero flow when needed.
• Thermal Regulation: Units are designed to operate above the dew point of hydrocarbons, maintaining vapor in a stable state to ensure reliable operation and machine longevity.
• Compact Design: Rotary screw VRUs generally offer a smaller footprint, making them easier to integrate into diverse site layouts.

How they work:

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2. Reciprocating Compressors/VRUs

Reciprocating compressors/VRUs are known for their ability to handle high-pressure applications, making them a viable choice in certain scenarios within the oil and gas industry. These compressors utilize pistons for staged compression, which helps manage temperature rise by cooling the gas between each stage. This design supports higher discharge pressures compared to some other compressor types, and the staged process is particularly useful in applications where consistent, stable vapor flows are present.

Key Features:

• Staged Compression: The multi-stage design allows for effective handling of higher discharge pressures, with each stage cooling the gas before further compression.
• Stable Operation: Well-suited for applications where vapor volumes and pressures remain steady, providing reliable performance in stable environments.
• Large Capacity: Reciprocating compressors are typically designed to handle larger-scale operations and are widely used in setups requiring significant pressure management.

While reciprocating compressors may have a larger physical footprint, they are versatile in high-pressure applications and remain an effective option for operations that benefit from staged compression and stable vapor flow.

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VRUs Tailored to Site Needs

1. Low-Volume Vapor Recovery Units

Application: Designed for marginal wells or small gas-gathering systems with lower vapor volumes rather than pressures.

How They Work: These units are engineered for single-stage compression with rapid adjustability to meet the demands of smaller, remote sites efficiently.

2. High-Volume Vapor Recovery Units

Application: Suitable for larger operations with significant vapor outputs. While “high-pressure” is subjective, these units handle large volumes efficiently, often feeding gas into pipelines at higher pressures.

How They Work: Similar to low-volume units but built on a larger scale to accommodate greater throughput.

3. High-Pressure Vapor Recovery Units

Application: High-pressure VRUs (Vapor Recovery Units) are essential for large gas processing facilities or production sites that need to manage significant vapor emissions, especially when discharging gas into pipelines or delivery points above 300 psi.

How They Work:

• Pressure Management: High-pressure recovery is focused on the delivery point pressure, meaning the VRU must be equipped with the right machinery to boost gas into pipelines at elevated pressures. For pressures beyond the capability of screw compressors—typically above 300 psi—a multi-stage reciprocating compressor can boost gas to even higher pressures effectively.
• Staged Compression Process: Often, our systems integrate both screw and reciprocating compressors. The screw compressors handle the initial VRU work, discharging into a reciprocating (recip) unit that boosts the gas to high pressure. This two-stage process allows for efficient high-pressure recovery from multiple well sources. In many cases, the reciprocating compressors pull gas from the entire field, lowering it to around 100 psi, before directing it into pipelines that may exceed 1000 psi.
• Specialized High-Pressure Applications: While high-pressure VRUs are rare, they can manage extreme conditions when required. For example, our units have handled inlet pressures of 175 psi, discharging at around 1200 psi, ideal for volatile gases with high demands. This level of operation can result in visual effects like frosting over pressure vessels due to the Joule-Thomson effect, demonstrating the unit's ability to manage extreme pressures and volatile gas effectively.
• Environmental Impact: High-pressure VRUs reduce greenhouse gas emissions by capturing and repurposing flare gas, which is crucial in minimizing the environmental impact of large-scale production sites.
• Separation: These systems separate liquid hydrocarbons and process the remaining gas, maximizing both environmental and operational benefits.

4. Flare Gas Vapor Recovery Units

Application: Specifically targets gases typically flared off, aiming to reduce emissions and improve resource utilization.

How They Work: Multi-stage compression is applied when necessary, especially in scenarios where gases are recovered from various flash sources. This setup allows efficient management of vapor volumes and enables the re-use or sale of captured gas.

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Choosing the Right VRU for Your Operation

Selecting the right vapor recovery unit (VRU) involves evaluating key operational needs and site characteristics. Here are some factors to consider when choosing the most effective VRU for your operation:

• Vapor Volume and Flow Consistency: For sites with lower vapor volumes and consistent flows, smaller VRUs, often with single-stage compression, are well-suited to capture vapors efficiently. In contrast, sites with fluctuating or high vapor volumes, such as large production facilities, benefit from rotary screw VRUs. These units adapt quickly to changing flow rates, ensuring effective vapor recovery.
• Operational Scale and Setup: For temporary or small-scale operations, portable VRUs offer an effective, flexible solution. Larger, conventional VRUs are ideal for permanent installations at facilities with high production levels, where vapor recovery is continuous and requires higher throughput capacity.
• Environmental Compliance: In regions with strict emissions regulations, VRUs designed to capture flare gas can help operators reduce greenhouse gas emissions by capturing vapors that would otherwise be flared. These units contribute to environmental compliance and improve the sustainability profile of the operation.
• Economic and Performance Considerations: When evaluating VRUs, it’s essential to consider both initial investment and long-term benefits. Screw compressor VRUs offer efficient operation and durability in high-BTU environments, providing reliable vapor recovery over time. Operators should weigh the upfront cost of the VRU against the value of reduced emissions, regulatory compliance, and potential revenue from recovered gas.

Why Choose Flogistix for Your Vapor Recovery Needs?

At Flogistix, we offer a range of vapor recovery units tailored to meet the specific needs of your oil and gas operation.

• Comprehensive Solutions: From low-pressure to high-pressure VRUs, including portable units, we have systems that meet your site’s unique demands.
• Advanced Technology: Our VRUs use the latest technology to ensure compliance with environmental regulations while maximizing hydrocarbon recovery.
• Proven Results: Flogistix systems are designed to recover the highest possible volume of hydrocarbons, transforming emissions into profit.

Don’t let valuable hydrocarbons escape. Contact Flogistix today to learn how our vapor recovery solutions can help you reduce emissions, increase profitability, and meet regulatory requirements.