13, May 2020 / rebound

Accelerating IQF Tunnel and Spiral Freezer Output in Food Production

Frozen food is produced using continuous freezers, like IQF (Individual Quick Freeze) tunnel or spiral freezers, that enable rapid freezing and subsequent quality preservation. And whether its prepared chicken wings, pizzas, strawberries or peas, the freezing process always looks similar: product is conveyed into an insulated enclosure where cold air removes heat from the product and refrigerant removes heat from the air.   

These freezers, while more or less identical on an architecture-level, are each sized specifically for the target application. Manufacturers use product type, temperature and target production rates to inform heat transfer requirements. These objectives then allow engineers to calculate the freezer size, evaporator coil surface area, air velocities and defrost frequency. The resulting installation is a continuous freezer that will meet the food producer’s needs. Unfortunately, there are two fundamental limitations all continuous freezers experience, regardless of design or application, that prevent producers from making critical, market-related operating strategy changes and instead lead to production bottlenecks.

Why are IQF and Spiral freezers a significant production line bottleneck?

Rigidity: Frozen food producers are locked into to a rigid freezer design the day it’s manufactured. It may be installed and operate well at design conditions, but it’s unable to adapt to intentional, or unintentional, production line changes. For instance, a producer may want to increase production output, change to a product with longer freeze times or simply manage the transient heat loads of a temperamental oven. In all three cases, the producer is stuck.

Moisture:  The production efficiency of most continuous freezers is reduced due to frost build up on evaporator coils. As the circulating air absorbs moisture from the product and deposits it on the frosting coils, effectively insulating them, the capacity of the refrigeration system falls. Poor heat transfer slows the freezing process leading to decreased production rates.

Non-ideal, but available solutions that alleviate some of this pain.

New Freezer:  Often dismissed due to the extended downtime required, a food producer can continue replacing their IQF or spiral freezers. Associated costs would include A) the new freezer, B) any required engine room upgrades and C) the cost of a 4 to 6 week production disruption.

Sequential Defrost: Modern continuous freezers often have the option to include sequential hot gas defrost. This process sends hot gas through the evaporator coils, one evaporator at a time, to melt the frost. While effective, it comes at the cost of either A) additional Capex due to additional evaporators required to meet production targets or B) a reduction in production because one evaporator will be out of operation. This process also introduces an additional heat load to the freezer that must be removed by the refrigeration system.

Add-on Desiccant System: Moisture can be controlled by add-on desiccant systems such as liquid desiccant or desiccant wheel technologies. These additions help control relative humidity, but also introduce an additional heat load to the freezer that must also be removed by the refrigeration system. The capital investment versus the value add is a non-starter from an ROI perspective.

Engine Room Expansion: Maintaining proper freezer temperatures, while managing high product heat loads, frost build up, heat from sequential defrost or heat from an add-on desiccant system, will require additional engine room capacity. Without a low temperature booster compressor and any associated high-pressure compression needs, the refrigeration system can’t provide the proper suction temperatures.

Why every IQF or spiral freezer owner must consider IcePoint capacity to accelerate production, immediately.

IcePoint is a revolutionary refrigeration technology that increases continuous freezer production by up to 20%, while avoiding:

  • freezer replacements
  • costly add-on desiccant systems
  • engine room expansions
  • additional ammonia use

Agility: IcePoint converts rigid IQF and spiral freezers into agile freezing assets. Integrated via an air handler, IcePoint generates and deploys a -40°F brine refrigerant that removes both sensible and latent heat from the freezer air, ensuring target air temperatures and moisture levels are always achieved. The ability to ramp a 28 TR system up to 140 TR of -40°F capacity, without efficiency penalty, enables IcePoint to adjust operating schemes to match production line needs.

Dehumidification: While sensible heat removal is the primary driver of freeze times, moisture-related issues such as reduced heat transfer efficiency, downtime and increased labor costs greatly affect profitability. IcePoint’s brine refrigerant manages moisture levels by drawing moisture directly into liquid solution without introducing additional heat loads. Product-specific moisture levels can be targeted to remove excess water without over-drying food or impeding heat transfer.

Food Safety: IcePoint helps avoid soft product by adapting to manage heat and moisture transients on the production line. IcePoint’s brine refrigerant is also naturally antiseptic. With a water activity of 0.7, the potassium acetate brine draws moisture from both air and any bacteria.

Revenue Generation: Increasing throughput by up to 20% has an enormous impact on profitability. Depending on product and freezer size, a single IcePoint system integrated into a single freezer can increase earnings anywhere from $2M to $4M, annually by adapting to meet transient sensible and latent heat loads.

Taking Back The Control.

Converting rigid continuous freezers into agile assets using IcePoint puts control back in the hands of operators. There is tremendous pressure on operations personnel to increase production, yet there are fundamental techno-economic constraints preventing them from meeting these expectations. It’s an impossible ask that can’t be solved economically with existing market technologies. Implementing IcePoint allows frozen food producers to avoid multi-million dollar infrastructure expansions that just trade one rigid system for another, and instead provides them with an agile, risk-free retrofit solution to safely boost production and profitability.