ANOTHER first time application for Flo Ice slurry, the rapid cooling of freshly caught salmon in road tankers.
The unique Flow Ice generator, designed and built by Pam Refrigeration in Cape Town, was commissioned in February 2013 for a salmon farm on the coast of Tasmania, an island south of Australia.
The output of three ton / hour of slurry (30% ice concentration) is stored in a bulk storage tank with agitator. From the tank the slurry is pumped into a semi-trailer road tanker. The mass of slurry pumped into the tanker is automatically controlled at the level set on the control panel of the filling system by the driver of the tanker. In summer months, the fill is set at seven ton and varies according to the season.
No blood to contaminate sea
Once charged with slurry, the road tanker is driven onto a barge, which travels to the 50 salmon breeding pens, 32kms from the truck landing. The salmon is automatically harvested from the circular breeding pens and sucked by vacuum pump to the on board-culling machine. The live salmon is first stunned and then culled by a pneumatic hammer, which strikes the head. The dead salmon, with any blood, then passes into the road tanker. All blood from the fish travels with the fish into the tanker as none can be discharged into the sea.
An automatic counter in the line limits the amount of fish into a tanker at 2,500. With a mass of 4,5 to 5kg each, the payload of the tanker averages 19tonne and once filled the barge returns to the coast. After being driven off the barge, the remaining space in the tanker is filled completely with slurry to stabilize the vehicle for the 350km journey to the processing plant.
Two barges, one with a single road tanker and another with two tankers operate during daylight hours of six days per week. Harvesting is restricted to daylight hours because of poor visibility at night. Each tanker averages one to two trips per day total four to six tanker loads per day.
Improved fish quality
Before installing the Flow Ice machines, a mixture of flake water was pumped into the tanker at the processing plant. Being only partially filled and with a slopping solution, the trailer was not very stable on the road and caused the driver unease, especially when having to stop suddenly and the load moved forward. With the Flow Ice system, the back haul from the processing plant is with an empty tanker and when traveling to the plant is completely filled, which adds to vehicle stability on the road.
The Flow Ice machine, packaged in Cape Town, has six ice generators, a Grasso 4.10 reciprocating compressor driven by a 55Kw motor. At -90C suction the package has a refrigerating capacity of 165Kw. A titanium shell and tube heat exchanger cools the incoming seawater from 14 to 00C before entering the ice generator. The change from flake ice to Flow Ice has lowered the fish storage temperature from four to 50C to 00C and the cooling rate is much quicker after culling, because of the fish being fully immersed in the slurry.
The fish company first made contact with Pam Refrigeration when they exhibited at an Australian trade show, and after months of negotiations and tests, the fishing company opted for the Flow Ice system and have already seen many benefits and an improvement of fish quality, because of the rapid cooling.
“The Australian market has shown much interest in our unique Flow Ice generator and more orders are negotiated for fish and other applications,” Evert Potgieter, MD, Pam Refrigeration, Cape Town.