Aquaculture Technology Implementation

Final Report

Newfoundland Aqua Service Ltd

AIMAP 2011-N03

Summary

The results of this initiative are very positive for Newfoundland Aqua Service Ltd (NAS). The major benefits that have been demonstrated include a greater efficiency for the overall operation. The time required to treat (or dip) a net has been reduced, and the time required to remove excess antifoulant from the treated net has been dramatically reduced by the impregnator. This process used to take anywhere from 6 to 16 hours, depending on the size of the net. The entire process now takes between two and three hours and is considerably less labor-intensive.

Another significant benefit of this technology is the reduction of wasted antifoulant on and around the equipment and in handling. The process is considerably more contained with this new technology and the spillage and dripping of antifoulant product have been drastically reduced.

Some operational issues were identified and addressed. Primarily mechanical issues related to the airlock and the impeller housing were satisfactorily addressed. These and other issues are documented thoroughly in this report.

Thanks to the AIMAP program for the support of the acquisition of this technology. It has enhanced the operational effectiveness and has introduced state-of-the-art technology to our company and industry operation.

Advantages:

• Improved dipping times
  • The impregnator has dramatically reduced the time between when the net has been dipped to when it actually can be hung to dry.
  • Before the impregnator became operational, NAS staff would have to submerse a net in a tank full of antifoulant called the dip tank. Using an overhead crane and slings, the net would be lifted and placed into the dip tank. After allowing the net to soak for an hour or so to become fully saturated with antifoulant, it would be taken out of the tank by the overhead crane and it would be left hooked up to the overhead crane directly above the dip tank to allow all excess antifoulant to drain and be recaptured back into the tank.
    • Depending on the size of the net and/or the demand to dip nets, a net could be above the dip tank for a duration of 6 to 16 hours. Normally, a net would be dipped towards days end so that it could be left above the dip tank until the following morning to be hung to dry.
  • After the installation of the impregnator, the need to leave a net hanging directly over the dip tank to recapture excess antifoulant was eliminated.
    • This is because the impregnator has two main processes when treating a net with antifoulant. There is an impregnating process and a drying process.
    • Prior to the impregnating process, dip is first transferred from the dip tank into the impregnator tank. Once completed, the impregnating process is started. During this process, antifoulant is transferred back and forth the impregnator tank and impregnator bag. The antifoulant is squeezed through the net in a vacuum like environment. This process usually takes an hour, however, this may vary depending on the size quantity of nets being dipped at a time.
    • Once the impregnator has completed its impregnating process, it goes directly into its drying process. During this process, all excess antifoulant is vacuumed out of the impregnator bag and is stored in the impregnator tank. There is no back and forth transfer of antifoulant during this process. This process usually takes an hour as well, and like the impregnating process, time can vary depending on the size and quantity of nets being treated.
    • Once both the impregnating and drying process has been completed, the operator then transfers all excess antifoulant removed during the drying process from the impregnator tank back into the dip tank.
    • On average, the entire process from start to finish can run between 2 to 3 hours, with the net ready to hang immediately.
  • The impregnator easily reduces the amount of time it takes to dip a net from anywhere from 4 to 16 hours simply because of its drying process whereby excess antifoulant is removed and therefore eliminates the need to leave it hanging above the dip tank. The recapturing of the excess antifoulant was the bottleneck in the entire dipping process and has been eliminated with the addition of the impregnator.
• Less labor intensive
  • Once the impregnator is loaded and the antifoulant has been transferred from the dip tank into tile impregnator tank, it can be started and the operator can step away until the impregnator is finished.
  • Using the old system of dipping nets, the person dipping the nets would have to stay near the dip tank to make sure it was submersed. Sometimes the person would have to physically pour dip over, the top of the nets, place weight on top of the net to get it to go down into the tank and also use the crane to roll larger nets in the dip tank top ensure that the net was fully covered in antifoulant.
• Reduction of our "Copper Footprint"
  • As mentioned earlier, the process of dipping a net using the impregnator decreases the amount of time it takes to dip a net and have it ready to be hung to dry. The reason is because of the drying process that the impregnator uses. It has a drying process where all excess antifoulant is removed from the net.
  • With the excess removed, it decreases the amount of antifoulant that could be potentially spread throughout our facility as it is moved from the dipping area into the drying area.
    • Using the old, method of dipping nets, even thou the net maybe left hanging over the dip tank to drain the excess, not all the excess would be removed.
    • There is accumulation of dip inside hoses used to protect rope loops at certain points of the net on certain customer's nets. The impregnator is able to remove the dip inside these hoses during the drying process.
  • At times, the demand for dipping is great; therefore, we don't have the luxury of letting a net, hang above the dip tank for any great amount of time to catch the excess because another net has to be dipped.

Operational Problems:

1. Airlock - On two separate occasions, midway through the process of dipping a net, the impregnator became stuck in the impregnating process.
   • During the impregnating process, the impregnator transfers dip from the impregnator tank into the impregnator bag. The dip enters the bag from the top lid. Once completed, it proceeds to vacuum out all the air and antifoulant through the bottom of the bag. All the air and antifoulant is pulled down through all the netting for a programmed time set up by the operator.
   • Once the impregnating cycle is finished the time required to vacuum out all the air and antifoulant, it goes into a relief stage whereby the vacuum is stopped and air is let back into the impregnator bag to begin the next cycle for impregnating. This relief cycle is programmed by the operator as well. Somewhere between the impregnating cycle and relief cycle, the system became airlocked, and the impregnator could not start another round of impregnating.
   • Solution: Use the system to manually bleed the impregnator bag and resume the dipping process.
2. Impeller housing - On two separate occasions, the impeller housing had to be taken apart and cleared of debris that had lodged inside.
   • Inside the impeller housing there is located a couple impellers that help create a seal by using water to enable the impregnator to perform its vacuuming functions.
   • Somewhere in the process, maybe transferring dip from the dip tank to the impregnator tank, some hardened dip that had settled on the bottom of the dip tank was sucked up in the process.
   • As a result, that hardened dip was injected into the impregnator bag and then sucked out of the bottom during the impregnating process and it ended up lodging in the impeller housing causing it not to work properly.
   • Solution: Take apart impeller housing and clean it up.
   • The new smaller dip tank was placed inside the old dip tank to allow for quick and easy set up of the old process of dipping nets in the event that the impregnator is down and out for any great length in time to allow production to continue.
     
     
3. Cracks and dents in impregnator tank - After using the impregnator for about six months, we noticed that dents and some cracks had appeared on the impregnator tank. This was noticed when one of the cracks started to leak some antifoulant.
   • This may be the result of poor manufacturing in combination with pressure exerted on the system during the impregnating process.
   • Contacted the manufacturer to see what can be done.
   • Solution: Weld cracks

Solution continued - new dip tank

• The old dip tank was too big (9' x 8' x 4') for use with the impregnator. In the beginning we used the same tank that we dipped nets into as the reservoir for our new impregnator.
• This was done so that if the impregnator had encountered problems whereby it would be out of commission for any great length of time, we could revert to our old method of dipping to keep up with our dipping demands.
  • The fill pipe that was inserted into the old dip tank that would transfer dip into the impregnator that was not put down to the bottom of the dip tank. Therefore, a lot of dip had to be kept in the dip tank to be able to run the impregnator a couple times to dip a couple nets without the need to have to fill the dip tank up with antifoulant on too regular of a basis.
• The antifoulant in the old tank was always agitated by a mixing motor and the action of dipping a net. At times, depending on the size of the net and how much antifouant was in the dip tank, a net would have to be rolled in the dip tank to ensure it was completely dipped. However, with the impregnator, there was no agitation from rolling nets. Basically, there was too much dip for the mixing motor to keep agitated and therefore some of the copper in the antifoulant began to settle on the bottom and become hardened.
• This hardened copper is what got dislodged from the bottom of the dip tank and transferred, into the impregnator that went on to cause the problems in the impeller housing.
• Therefore, we decided to construct a new dip tank about half the size (roughly 4' x 4'x 7') and a different shape bottom to discourage the settling. Also, the mixing motor would work better having to agitate less antifoulant.

Summary:

Overall, NAS is very pleased with the new impregnator technology. It works very effectively and ensures good coverage of the nets and does the job in a timely and environmentally sound fashion.