Challenge
A chemical plant in Texas required a 24,000 barrel tank to be degassed during, and following a tank cleaning. The degassing was performed under a nitrogen blanket, with an outside tank cleaning company water washing the tank. The customer’s main concern was to keep the pressure in the tank constant, while maintaining a steady flow of nitrogen into the tank. Tank pressure had been a previous issue for the customer in the past with a different degassing company. The customer wished to keep the pressure within 2” WC of the current pressure.

Solution
Due to the high levels and fluctuations of benzene, the Envent engineers decided to use a thermal oxidizer routed directly to the flame arrestor on the tank. Constant communication was kept between the control room, and Envent personnel throughout the degas to keep the pressure equalized. Envent provided benzene readings to the control room every two hours, per the customer’s request. The benzene concentration was relatively high during the agitation of the tank, about 700 ppm, but dropped significantly after the tank cleaning company had finished. Envent provided a reading of 0 ppm to the control room, which was confirmed by the customer’s lab.

Benefit
To the delight of the customer, Envent was successfully able to degas the benzene tank with a nitrogen blanket during the three days of tank cleaning. With a 24 hour manned watch, the thermal oxidizer outperformed previous competitors, and gave a final benzene reading of zero ppm. Through constant communication with the customer, Envent was able to safely meet the strict requirements set forth by the customer. Envent was also able to save the customer money by significantly reducing costs by shortening the duration of the project.

Degassing Tanks under a Nitrogen Blanket Not a Problem for EMTOS

Challenge

A refinery in Pennsylvania was in the process of re-commissioning a 12-inch propane pipeline when a leak was detected. The compromised section spanned approximately 16 miles between two stations and contained over 12,000 barrels of liquid propane. Due to the high vapor pressure and flammability of propane, the product needed to be safely combusted and removed as quickly as possible to prevent environmental and safety risks.

Solution

Envent Corporation responded with a custom-engineered vapor control solution using:

• Two 200-gallon/hour propane vaporizers to convert liquid propane into gas

• A 20 MMBTU/hr Envent Mobile Thermal Oxidizer (EMTOS) to achieve complete vapor destruction with >99.9% Destruction Removal Efficiency (DRE)

• A dual-use approach: vaporized propane was used both as combustion fuel and as the process vapor for destruction, maximizing thermal efficiency

This mobile degassing strategy enabled the pipeline to be depressurized four times faster than traditional methods, significantly reducing downtime.

Benefit

By utilizing Envent’s thermal oxidizer system—which includes a detonation arrestor and complies with stringent safety standards—the pipeline was safely degassed and brought to atmospheric pressure without the risks associated with mobile flaring.

Key project benefits included:

• Enhanced safety through engineered vapor combustion and flame arrestor protection

• Faster project completion, minimizing downtime and production loss

• Full regulatory compliance with federal and state air quality standards

• Safe, efficient, and environmentally responsible management of high-BTU propane vapors

This project illustrates Envent’s capabilities in pipeline vapor control, zero emission pipeline services, and thermal oxidation for high-risk hydrocarbons—delivering expert solutions when safety and speed matter most.

By using the vapors in two ways, the time to depressure the pipeline was completed 4 times as fast.

Challenge
A tank farm customer requested Envent be onsite for an unscheduled tank refill within 4 hours. The fill rate was to be 2500 barrels/hour of gasoline. The tank size was 250,000 barrel tank with a slotted gauge vapor connection point.

Solution
Envent was able to mobilize an Emtos 2500 thermal oxidizer within the hour. Envent was onsite within two hours and set up and ready to process vapors within the 4 hour time frame. The thermal oxidizer captured and destroyed greater than 99.9% of all vapors displaced by the refilling of the gasoline tank.

Benefit
The tank farm was able to complete the tank refill on schedule with no down time. Envent was able to respond to the emergency quickly and safely, which saved the customer thousands of dollars in down time.

Envent was able to respond to the emergency quickly and safely, which saved the customer thousands of dollars in down time.

Challenge
A pipeline company in Northern California needed to blow down their natural gas pipeline for repairs and inspection. The 18” line was initially depressured to the minimum possible pressure, which still left 90 PSI of natural gas. Also, the zero-liquid condition could not be determined prior to operation.

Solution
Envent efficiently mobilized a high pressure separator and a thermal oxidizer to blow down the pipeline within a short period of time. After destructing the remaining gas in the line with the EMTOS unit, four volume line sweeps were performed to leave the piping free of residual gas. After the blow-down, the customer could reroute the interconnecting piping, hydrotest the new portion and recharge the lines back up to 400 PSI.

Benefits
Due to Envent’s sound planning and efficient engineering approach, the pipeline company could finish their modification on schedule and safely in environmental compliance of the local air board. A great saving was achieved when the downtime was reduced by Envent operations.

Four volume line sweeps were performed to leave the piping free of residual gas.