Challenge
The sulfur unit in a refinery needed back up for its existing odor control system which was no longer handling its load due to particulate clogging.
Solution
We spec’d out three different solutions to their odor issues; the first solution provided was 4k lbs of darco carbon, the second option given was our custom formulated VapoScrubH2S5 in a passive chemical scrubber, and the third option was a sodium hydroxide solution, aka Caustic.
Benefit
VapoScrub™H2S5 yielded the best and most economical option giving a total cost saving of $200,000 over the duration of the project.
Challenge
A petroleum manufacturer contracted Envent to do vapor control on a series of frac tanks being filled with shale oil from a pipeline. There were a total of 30 frac tanks. We were asked to provide vapor control systems for each set of 15 frac tanks.
Solution
The first 15 frac tanks were manifolded together and connected to our ESCRUB™ 1000-P, Single Column Passive Chemical Scrubber filled with our VapoScrub™EX5. The second set of 15 frac tanks were connected to a passive carbon system. Our stand alone passive chemical scrubber filled with VapoScrub™EX5 did magnitude better than a standalone carbon vessel.
Benefit
The cost savings from the price of the solution and from the absorption capacity amounted to a $21,000 savings for our customer.
Port Arthur, Texas, Liquid Ring – High Volume, Vacuum Truck Vapor Control
Challenge
A refinery needed to abate vapors following a super sucker vacuum truck (3000 CFM) containing high concentrations of H2S and residual VOCs.
Solution
The designated unit was our high performance and high flow EVAC 6000. It is a recirculating chemical scrubber with trailing twin 4k carbon vessel.
Benefit
Our high performance scrubber had a higher efficiency and a longer lifetime then our competitors’ scrubber who had previously done this job. The cost savings versus carbon was estimated to be $100,000.
Challenge
An oil pipeline company was clearing 25 miles of 16 in pipe into a crude tank. The oil had an API of 12˚. The company needed the line cleared soon as possible.
Solution
Envent specified the BD-8000.
Benefit
We were able to complete the job with an efficiency of greater than 98% and an estimated cost savings over carbon of $30,000.
Challenge
A refinery contracted Envent to use our EVAC 1000 unit to do temporary odor and vapor control for its sludge processing centrifuge operations.
Solution
We brought out three scrubbers; the first scrubber was a dual GAC passive scrubber, the second was a dual GAC passive scrubber following Diesel sponge oil, and the third was our EVAC 1000, with our custom VapoScrub™EX5 scrubbing solution.
Benefit
With carbon following our VapoScrub™EX5 solution we were able to make the GAC last approximately 3 times longer savings the customer approximately $150,000.
Challenge
Emergency Response Call-out to depressurize a 13 mile long section of 12 inch pipeline containing butadiene. Required to line depressurize from 250 PSIG to 0 PSIG. Envent engineered and was on-site within 2 hours, in the middle of the night.
Solution
Envent engineering team deployed 2 EMECS 42 Units and depressured the line.
Benefit
The project was completed without incident. Envent received commendation from the project manager.
Challenge
An Envent account manager received a call from a customer that prefers the use of internal combustion engines for tank degassing. And though Envent has a fleet of IC Engines, we use them for small tanks and vessels. The customer called to schedule a meeting to discuss using thermal oxidizers for tank degassing.
Solution
The customer indicated a serious incident that had taken place in the facility a few weeks earlier while a degassing company was performing vapor control on a gasoline storage tank. The issues swirled around a flash fire that occurred during the vapor control. Apparently the combination of a warm day, high vapor pressure, a swift breeze, and an open manway led to vapors being pulled from the tank and out into the tank basin. The puddling vapors ignited when a vehicle entering the tank basin passed through the vapors, causing a flash fire back to the tank. The flames continued to leap from the tank manway until extinguished by the fire department. It had been determined that the IC Engine pulling vapors from the tank could not pull fast enough to overcome the environmental conditions. Envent explained to the customer that the mid-sized EMTOS 3500 Thermal Oxidizer has a flow rate that averages seven times the flow rate of a dual IC Engine unit. Had the EMTOS 3500 been used to perform vapor control on the facility tank that caught fire, vapors would not have been released from the tank.
Benefit
Because thermal oxidizers flow so much better, vapors that would normally overload an IC Engine and be sent back to the tank can be routed straight to the thermal oxidizer. The EMTOS systems are specifically designed not to circulate vapors back to the source; be it a tank or vacuum truck or aeration basin. Envent’s thermal oxidizers and carbon scrubber systems receive and process all vapors the first time around. The customer stated one of his reasons for resisting using a thermal oxidizer for so long was due to the size of the equipment. The Envent account manager explained that for an IC Engine system to achieve the same flow rate, seven IC Engine units would be needed, therefore taking up much more room than one EMTOS 3500.
Challenge
One of Envent’s national customers contacted an Envent branch location regarding the need for a copy of Envent’s tank degas procedure “As soon as you can.” The customer indicated that a serious incident had occurred a few days earlier at one of their local petroleum processing facilities. Envent sent the tank degas procedure. For the purposes of hazard communication, the customer sent a copy of the safety bulletin and urged Envent to share with all employees. The safety bulletin indicated a tank cleaning and degassing company had been contracted to degas and clean a Gasoline storage tank. During degas the contractor had experienced a series of several small explosions inside the facility tank. The explosions were described as sounding like someone knocking on the side of the tank. After several “knocks” the degassing operation was shut down and the area evacuated. Investigators discovered the floating roof had torn away from several of the landing legs and the roof had partially collapsed.
Solution
In the following weeks and after a thorough investigation, it had become apparent the cause behind the mysterious knocking sound during degas. The tank cleaning division of the contracted company had submitted a fixed price tank cleaning bid and was pressing the degassing division to expedite their scope of the project. What resulted was a decision to water wash the tank while the vapor space was at or near 100% LEL. The jet of water shooting into the tank caused static discharge and thusly, detonation of gasoline vapors that had combined with oxygen drawn into the tank by the degas equipment. Essentially, the water became the spark plug in a very large, very powerful internal combustion engine; the floating roof acting as the engines piston. Since the close of the investigation, the customer has incorporated Envent’s degassing procedure into its project bid requests and master tank cleaning and degassing sequence. That procedure and sequence specifies no water washing until tank vapor space is tested and confirmed to be below 50% LEL. The customer has also understands the importance of keeping tank cleaning and tank degassing as two completely separate scopes of work.
Benefit
Having one company provide both services creates a conflict of interest where checks and balances are compromised. Among several other vapor service lines, Envent degasses tanks. Being a tank degassing specialist, Envent does not dilute its attention to detail in an effort to capture more work scope and therefore more project revenue. Envent has not, does not, and will not clean tanks. Leave tank cleaning to the experts. Leave tank degassing to Envent.
Challenge
A customer came to Envent with an invitation to bid on an upcoming tank degas project. It was stated that facility storage tank 395 was to be degassed, cleaned, and then demolished. The external floating roof tank had been in slop oil service. By the time of bidding, the tank had been decommissioned for several years. The tank was approximately 100′ in diameter and 40′ shell height. Since the roof had landed on its legs a few years earlier, the customer was sure vapors were minimal. The logic being the vapor pressure would have pushed past the roof seals over time, venting the contents to atmosphere. Envent prepared a proposal that considered the customer’s assertion the tank would need minimal degassing. Also included was an additional degas duration that took into account a realistic duration given the release of vapors likely released when the sludge inside the tank was stirred. Envent’s expertise in tank degassing over the past 25 years provides the customer a vast library of scenarios and typical outcomes. Also included was a very important notice to the customer that Envent would not begin degas procedures until it was positively confirmed and proven no pyrophoric material was present. Envent includes this message on all proposals for tanks of this type due to the unknown nature of “Slop” and the explosive risks.
Solution
A few days after bidding was closed, Envent followed up with the customer on the proposal submitted. The customer informed the account manager that Envent’s proposal seemed excessive in its duration and that no pyrophorics were present. Again, the logic being this tank has been venting to atmosphere for a few years. If pyrophorics were present the tank would have overheated years ago. “All I need to do is satisfy a requirement to degas.” Envent was not awarded the tank 395 degas project due to price. About two weeks after the award of the project, local news outlets ran a breaking story of an explosion and fire at a local petroleum processing facility. Photos on the news showed the shell of tank 395 partially caved in and smoke billowing from inside. Aerial photos showed the tank roof lying flat on the ground about 20′ from the tank. The ensuing investigation determined that incomplete degassing and a pyrophoric reaction inside the tank had caused an explosion that launched the floating roof several feet into the air. Except for a few cuts, bruises, and rattled nerves, thankfully nobody was injured! Envent has always asked about the possible presence of pyrophoric material. Hindsight is always 20/20, but the customer would agree, Envent’s precautions were valid and warranted.
Benefits
Envent brings experience to the project site. With experience comes the knowledge to ask the right questions. In this case, asking about the presence of pyrophoric material was one aspect. The follow-up on the answer is just as important. If the answer in “No” to pyrophorics, can you prove it is “No” with a lab sample and analysis? If the customer does not provide the information needed to safely perform the degas, should you still proceed? Why ask for the information if you’re going ahead anyway? Another benefit of experience is being knowledgeable enough to enforce safety boundaries. Just because a customer provides a Purchase Order that does not mean your degassing provider should do the work at any cost. Certainly not the cost of equipment or facility damage, or worse…
West Coast Refinery, Vapor Control on Arabian Crude Tank
A refinery company on the West Coast needed to de-inventory a tank of Arabian Crude with unexpectedly high hydrogen sulfide levels. After receiving multiple odor complaints from within the refinery and one odor complaint from the public, the client knew they needed to resolve the issue immediately. Depending on the conditions of the hazardous release, the AQMD (Air Quality Management District) has daily fines ranging from $1000 to $1,000,000.
Solution
To control the hydrogen sulfide vapors during the de-inventorying process, Envent deployed two ESCRUB-1000’s (Envent Scrubber) in series: 1000 SCFM recirculating scrubbers. Following the two ESCRUB-1000’s in series, the EMTOS-3500 (Envent Mobile Thermal Oxidation System) destroyed the other off-gas constituents.
Benefit
Due to Envent’s immediate mobilization for the project, the client saved at least $100,000.
Challenge
A refinery wished for a bullet tank of Ammonia to be degassed. Due to limited space availability equipment that provided a small footprint was needed. The tank also needed to be degassed as quickly as possible so an inspection and repairs could be made.
Solution
Envent was able to provide an ESCRUB 1200. The liquid recirculating scrubber was able to take over 10,000 ppm of ammonia down to 0 ppm. The Envent designed packing material and proven liquid media was able to cost effectively reduce the ammonia concentration while limiting media changeout.
Benefits
The refinery was able to do critical lifts in the area without any odors that would have stopped operations. Envent was able to degas the bullet tank without any infraction of the degassing permits for the facility.
Challenge
A sour water tank high in H2S needed vapor control provided during a turnaround while maintenance was done in the surrounding area. The H2S concentration was as high as 500,000ppm during parts of refinery operations. The H2S needed to be reduced to a safe level while the vapors were treated and vented to atmosphere.
Solution
Vapors from the tank were routed to a liquid recirculating scrubber, which reduced the H2S concentration to an acceptable limit to where the vapors could be sent to a thermal oxidizer. Envent monitored the inlet and outlet of the liquid scrubber to ensure efficient reduction of the H2S. When liquid break through was approached, the media was changed out to guarantee the thermal oxidizer was always combusting vapors that were below the threshold of EPA mandated levels of H2S combustion.
Benefits
Envent was able to successfully reduce the H2S emissions in the area so a turnaround could continue. Also, Envent was able to adjust to severe cold conditions and prevent solidification of the liquid media. This prevented costly delays while maintaining safe turnaround operations, eliminated odors and kept the customer in compliance.
