What is a Vapor Recovery System, and how does a Vapor Recovery System Work?
In the downstream segment of oil and gas operations, it is essential to remove all harmful vapors with all the toxic and explosive properties from gasoline and many other fuel types before the products are sold.
Vapor recovery is particularly important as hydrocarbon storage containers may be inclined to leaks via safety valves and hatches as the internal vapor pressure builds up over time.
Table of Contents
What is Vapor Recovery System?
Vapor recovery is the simple process of eliminating harmful vapor and fluid contaminants from crude products to and prevent the release of toxic pollutants into the environment and to improve the purity. In chemical processing industries vapor removal is done to recover all the unwanted vapors from storage units and to keep the chemicals safe and pure for transport.
Is Vapor Removal Mandatory?
In several countries, the specifications of vapor removal are enacted by environmental protection authorities, mandated by law, and binding on all producers and operators involved in the processing and storage of natural gas, petroleum, and petrochemical products.
In the United States of America, The EPA commands all the operators to extract vapor removal to regulate harmful air emissions in hydrocarbon storage facilities, natural gas processing plants, and natural gas wells under the New Source Performance Standard 40 CFR, Sub-part OOOO, Part 60, also known as the ‘Quad O.’
Under this new regulation, operators must remove at least 95% of vapors produced in hydrocarbon storage units. The new standard places have increased demand on gas and oil management to devise sustainable ways to decrease vapor pressure in tanks and prevent costly emission releases. One of the most powerful and effective systems for vapor removal is the vapor removal unit (VRU).
What is a VRU?
A Vapor Recovery Unit (VRU) is a set-up designed to eliminate unwanted vapors present in crude oil or distillate tanks and allowing several operators to comply with prevailing emission regulations.
VRU systems can be employed in a various range of chemical industries with many variants available. For example, a vapor recovery system for large storage tanks can be especially used to recover vent gas from crude oil and easily distillate tanks at storage facilities.
Vapor Recovery System – How It Works
VRUs are mechanically driven and are powered by a gas engine or an electric motor entirely depending on what’s available.
The working principle of VRU is primarily based on the Ideal gas law, i.e. (PV = nRT or pressure x volume = gas mass x temperature x gas constant). In essence, when you compress your process gas into a lesser volume, the pressure of the gas increases.
The typical VRU consists of four principal components:
- Gas Compressor
- Variable Frequency Drives (VFDs)
- Scrubber
- Switching device
1. Gas compressor
Many types of vapor recovery compressor package may be used especially for vapor removal including, rotary sliding vane, flooded rotary screw, and reciprocating piston compressors or any model which uses the principle of positive displacement.
2. Variable Frequency Drives (VFDs)
The Variable Frequency Drives (VFD) is an electromechanical driver system whose major function is to modify the speed of the compressor depending on the rate of flow of gas into the VRU.
3. Scrubber
The scrubber is an essential device used to remove fluid impurities from a natural gas flow stream. Scrubbers and fuel gas conditioning systems are an important addition to VRUs for distillate tanks with high BTU vent gas and dealing with vapors in crude oil.
4. Switching Device
The switching mechanism in a VRU identifies changes in pressure inside the tanks and instantly activates the compressor. The major function of the switching device is to start and stop the operation automatically depending on the condition of the pressure inside the tank.
How Does a Vapor Recovery Unit Work?
The major function of a VRU system is to eliminate the vapors that collect inside sealed hydrocarbon tanks. The machine does this effectively by suction and gas compression.
The vapor recovery procedure involves the following steps:
- The rotary screw gas compressor insert liquid molecules into the scrubber
- The scrubber eliminates the debris, water vapor, and unwanted fluids from the tank.
- The recovered vapor is eventually pumped into gas lines while the trapped liquids are channeled directly to the pipelines.
Conclusion
With Vapor Recovery Unit (VRU), industries can recover air pollutants and other vent gas safely, ensuring compliance with emission regulations.
SAVAS Vapor Recovery Systems are good and ideal vapor recovery solutions for the petrochemical and petroleum industries. The technology make use of the best membranes in the industry to treat several range of vapors in hydrocarbon and chemical storage units.