Net Drying Innovation in Aquaculture Servicing

Final Report
Newfoundland Aqua Services Ltd
AIMAP 2012-N02

1.0 Introduction

This document provides a report on the activities that have been undertaken to develop an innovative aquaculture net drying system with assistance provided by the Department of Fisheries and Oceans Aquaculture Innovation and Market Access Program (AIMAP). The activities are outlined and documented; the challenges encountered are identified and discussed; the outcomes to this stage are documented; and an overview of further initiatives planned is provided.

While there is a requirement for additional work to achieve the desired parameters of the net drying process, the work completed and the technology employed through the AIMAP initiative have been extremely valuable to Newfoundland Aqua Services Ltd.

Some background to the initiative will provide perspective.

2.0 Background

Newfoundland Aqua Services Ltd (NAS) has been conducting a pilot project to adapt technologies to establish land-based net washing operations in NL with financial assistance from Atlantic Canada Opportunities Agency (ACOA), AIMAP, and Provincial programming. NAS has been the sole provider of net repair, washing and treatment services to the Coast of Bays finfish aquaculture industry for the past 15 years.

Traditionally and currently, net washing has been conducted on floating barges located in the same marine environment in which the finfish aquaculture is conducted. This poses a biosecurity risk. Other finfish aquaculture jurisdictions have moved these activities to land based sites to mitigate biosecurity risks. NAS has undertaken a review of practices and technologies employed in Norway, Scotland, New Brunswick and British Columbia.

After the cleaning and disinfection process, nets are treated with copper-based antifoulant and then dried before they are ready for use. Previously, NAS relied upon natural air-drying by hanging the nets on large poles out of doors, and the use of electrical fans in a net drying building to 'blow-dry' nets. This arrangement, which is also utilized in some other jurisdictions, is weather dependent, slow and not suitable for the requirements and timing of customers.

NAS investigated drying technologies and has worked closely with two experienced firms - Peter Stette AS of Norway, and Geo-Xergy Systems Inc of Winnipeg. NAS intends to utilize geothermal sourced heat in the drying process.

4.0 Trials and Performance

The installation and operation of the new technology has acted as a trial project to determine how the equipment functions, both as individual components and as an integrated system. The final system will be installed at the new land based facility at Mill Pond. A key piece of this trial has been to determine the adequacy of the Coke Dry Quenching (CDQ) technology, and to assess the need and potential to include the Stette technology in the drying / dehumidification process. Another key element of the trial has been to determine the compatibility and performance of the integrated system.

There have been very significant delays in establishing the equipment and systems, and in the execution of trials. Delays in the supply and delivery of the specialized equipment occurred. As detailed later in this section, delays were also encountered as a result of certain components not being included with equipment delivery and subsequent modifications being required. The initial installation of the CDQ technology commenced in June 2013. The complete installation and initial commissioning were not undertaken until November 2013.

It may be useful to identify some of the challenges and problems that were encountered in establishing the system.

4.1 Challenges and Problems

One of the challenges that is common to many aspects of the developing aquaculture industry in Bay d'Espoir is the lack of ready access to certain specialized skills and trades. In the case of this project, the absence of skilled HVAC and refrigeration tradespeople was a real impediment.

Some of the problems encountered included:

• Omission of key components to system setup. During initial installation of Programmable Logic Controllers (PLC) and heat pump commissioning, it was discovered that starters for the two pumps and the air handling unit on the CDQ side were not installed. These items had to be ordered and installed and caused a delay in the project.
• During the initial commissioning of the CDQ unit and disinfection system it was discovered that some equipment had been installed in the wrong locations and that changes had to be made in order to properly commission these systems. Additionally, this was only determined late in the time frame established for commissioning and the technician had to leave site. NAS then had to make arrangements to position the equipment correctly and then proceed to flush the system and finish the commissioning process.
• NAS made the proper changes to the equipment, however, lacked the knowledge and expertise to perform the flushing procedures. Consequently, NAS hired HVAC Specialties Inc to come onsite to perform flushing procedures and to finish commissioning.
• Failure to start CDQ unit. Temperatures in the net drying room were too low entering the CDQ unit during start up resulting in the CDQ unit not starting. A secondary source of heat was required to prime net drying room in order to have the CDQ unit start working. The solution developed was to integrate two of NAS' existing 6 ton water to air geothermal heat pumps to prime the building prior to starting of the CDQ unit.
• Problems in achieving continuous operation of CDQ unit.
  • Heat pump cutting out on various temperatures on the cooling side;
  • Difference in actual temperatures and program set points causing heat pump to cut out on predefined safety limits;
  • Possible causes were identified: sensors reporting temperatures to PLC controls were not properly placed into fluids in the system.
• Solutions:
  • Temporary: monitor temperatures and system to identify the actual temperature limits creating this scenario and adjust PLC limits to allow CDQ unit to work within those parameters.
  • Permanent: reposition sensors or replace with a different type of temperature sensor.
• Temperature stratification in net drying room:
  • Air temperature within the net drying room was inconsistent, air entering the room from the CDQ unit at the top of the building was around 40 degrees Celsius and temperatures at ground level was 10 degrees Celsius.
    Solution: Installed 6 industrial ceiling fans to draw hot air from the ceiling and distribute down throughout the building volume.
• Failure to operate disinfection system:
  • Once the disinfection side was ready to commission, it was started for a trial and testing. Shortly into the process, problems were identified with the high heat pump. It was unable to generate the high level of heat that it was designed to produce. These high heat pumps were designed to heat water to a temperature of 60 degrees Celsius and it was only able to produce 34 degrees Celsius.
  • After trouble shooting the high heat pumps, it was determined that they were operating correctly, the problem resided with the supply of hot water to this heat pump from the CDQ unit.
  • Running the CDQ system and disinfection system at the same time, the disinfection system would draw all available heat within both systems and still not be able to achieve the high temperatures it was designed to produce.
  • The CDQ system is unable to maintain a sufficient supply of hot water to the high heat pump on the disinfection side.
  • A potential solution has been identified -adding capacity for hot water to the overall system.
• Failure to integrate CDQ system:
  • The integration of the CDQ system with the existing heat pump system and the new disinfection system has been troublesome and less than satisfactory. Potential solutions have been identified, but these need to be implemented and tested. Additional trials are planned and alternative designs and strategies are being considered.

4.2 Positive Results

The positive outcome is that the system does dry the nets, but it has not yet been determined whether the system as configured will provide adequate capacity or perform within the desired parameters.

The net drying results were inconsistent, perhaps not surprisingly in context of the considerable debugging and fine-tuning required.

A limited number of large nets were dried in the trials. The nets were 100 m x
16 m, with 2 1/4 inch mesh. The amount of time required to completely dry the nets was 24 hours; 18 hours; 14 hours and 20 hours.

Trials will be continued in the immediate future to implement planned system improvements. Some of the considerations and planned system improvements include:

• Implementation of ceiling fans to overcome stratification effect of temperatures;
• Adding hot water capacity to the system in order to increase supply of hot water to meet the demands of the CDQ system and disinfection system in order to facilitate both processes operating at the same time;
• Implementation of more and strategically placed fans within the net drying room to better circulate the air within the drying room.
  • Sections of netting that were exposed to a fan blowing air directly at it dried quicker than areas that didn't.
  • Forced air as opposed to passive airflow.
• Design and implementation of a secondary source of heat to pre heat the net drying room prior to starting the CDQ system.

These considerations and planned measures will be evaluated to determine whether they will result in functioning of the system within the desired parameters, or whether the addition of the Stette drying technology will be considered and evaluated.