Super Air Knives Save 63% Electrical Cost for a Food Manufacturer Drying Trays

A food manufacturing company was looking for a more efficient way to dry polypropylene trays that were filled with food product. With their current operation, they would send already packed and sealed food trays through a washing system that used sterilized water. The trays would then have to be dried prior to bulk packaging. The operators would place the trays side by side on a 24” wide open-mesh stainless steel metal conveyor with two or three trays at a time (depending on the tray dimensions). They contacted EXAIR because they wanted to replace their “old and inefficient system” with something better.

In my discussions, they gave some additional details of the operation and the problems that they were seeing. The dimensions of the trays ranged from 150 to 200mm long by 100 to 150mm wide by 35 to 50mm in height. They were cleaning at a rate of 30 trays per minute through the washing and drying system. The washer was designed to recycle the water to improve “green” operations. But the trays were carrying much of the water outside the machine. Thus, they would have to stop and refill the wash system with fresh water.

After the washing cycle, the drying section began. It consisted of two parts; a sponge roller and a heated chamber that would blow hot air. First the trays would run under the sponge roller to absorb the water from the top of the trays. A feature that they did not like was the continuous adjustment to the sponge roller for the different tray heights. They had to make sure that they had good contact without stopping the movement.

Also, with bulk of the water being on top of the trays, the sponge surface would get saturated. They would have to stop the process to change with a dry foam pad or replace due to wear. After the sponge roller, it would move into a heated chamber to remove the remaining portion of the water from the trays. They used a 11 KW heating system to blow hot air. This part of their system required a lot of electricity to run. They wondered if EXAIR could help streamline their process and reduce energy costs.

They sent a photo of their system, reference above. As described, the trays were moving intermittently through the wash cycle and then into the drying operation. When gaps are present in a process, the Electronic Flow Control, or EFC, becomes a great product for energy efficiency. It is designed to use a photoelectric sensor to detect a part and initiate a timing sequence. Using a solenoid valve, it will turn on the compressed air only when needed. With the drying operation, I suggested that they could remove the sponge roller and heated chamber, and replace them with two Super Air Knives. In conjunction with the EFC, we can decrease energy usage, reduce downtime, and increase savings. Profit margins can be critical in the food industry, and EXAIR has many ways to help.

Electronic Flow Control

To expand a bit more about revitalizing the “old and inefficient system” with EXAIR products, I made some suggestions. I recommended two Stainless Steel Super Air Knife Kits, model 110224SS, to be placed near the end of the conveyor. One Super Air Knife would be positioned above the tray to blow across the top; and one would be positioned below the tray under the mesh conveyor to blow across the bottom.

At a slight blowing angle in a counter-flow direction, the air streams would remove the water from the top and bottom of the tray at the same time. This would create a non-contact “wiping” solution. Now they do not have to worry about parts wearing out due to contact. Another unique feature of the Super Air Knife is the strength of the laminar air stream. It is consistent from 3” (76mm) to 12” (305mm) away from the target. Thus, they can easily set the height of the Super Air Knives to dry all the different trays without adjusting it.

And as an added benefit, the water that was being blown off the trays by the Super Air Knives remained within the washing system. The sterilized water was not being wasted and could be recycled. With the Electronic Flow Control, I recommended the model 9056. It is a user-friendly device with eight different timing sequences. They were able to position the photoelectric sensor near the outlet of the washing system. As soon as the trays were detected, the Super Air Knives would turn on to blow two or three trays at the same time. With the EXAIR products installed, the system went from using 11 KW down to 4 KW, a 63% savings.

EXAIR has helped many customers like this one above. When it comes to energy savings, EXAIR leads the way. With two Super Air Knives and an EFC, we were able to modernized their system; save on water, improve productivity, reduce the overall footprint, and save on their energy usage. If you have a similar application, you can contact an Application Engineer at EXAIR. We will be happy to update your system.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Compressed Air Knives vs. Blower Air Knives, an Application Comparison

A company was needing to dry vegetables after a washing system.  They currently had three blower air knives (as shown in the photo above) to remove the water before packaging.  The issues that they presented to me were in two parts.  They were not able to generate enough force to remove enough water from larger products like cauliflower and broccoli.  And, the heat from the blower system was affecting the appearance of the thinner vegetables like snow peas.  They purchased the blower-style air knives under the belief that they would save money by not using compressed air.  They found out quickly that it was not a true statement especially when it comes to the total cost of ownership.

Super Air Knife drying fruits and vegetables

When comparing the EXAIR Super Air Knife to a blower-type air knife, there are many features that should be reviewed.  For the customer above, they used an 18” (457mm) wide conveying system to wash more than twenty different fruits and vegetables.  So, they needed versatility to dry the different types of products.  With the Super Air Knife, we have a simple way to adjust the force by changing the inlet air pressure.  So, we can blow air at a light breeze for the snow peas to a very strong force to dry the cauliflower and broccoli.  With the engineered design of the Super Air Knife, we can achieve a 40:1 amplification ratio.  That means for every 1 part of compressed air, we are able to entrain 40 parts of ambient air.  This unique feature allows for the Super Air Knife to be very efficient with your compressed air as well as keeping the blowing air at ambient temperatures.  The design of a blower system allows the air to become hot, turbulent, and limited in force.  As noted in the photo above, they had to use three blower knives to try to remove the liquid water.  With the Super Air Knife, I recommended just one air knife to do the job.  They decided to try an EXAIR model 110218SS 18″ Stainless Steel Super Air Knife Kit to see if their concept of “saving money” with the blower-type air knife was valid.

To better explain the concept, I divided the comparisons into different categories.  You can decide if the Super Air Knife would be a better product than the blower-type air knife.  It sure was for the customer above.

  1. Initial Cost:
    1. Blower System – They are an expensive product when you have to include a blower, ducting, and a knife. To have any flexibility, a control panel with a VFD will be needed.  A capital expenditure is typical for a complete system.
    2. Super Air Knife – It is a fraction of the cost. With their system above, we were roughly 1/10 the cost.  A capital expense would not be required for ordering a Super Air Knife to remove the water.
  2. Maintenance:
    1. Blower System – The intake filter has to be changed periodically as well as the motor and belt has to be checked as a preventive maintenance. Being that the blower motor is a mechanical device, the bearings and belts will wear and have to be replaced.  Without proper maintenance, things can break prematurely.  Loss of production will cost you much money.
    2. Super Air Knife – They do not have any moving parts to wear out. Only compressed air is needed to operate.  The maintenance requirement is to change the compressed air filter once a year.
  3. Compressed air usage:
    1. Blower System – This device does not need any compressed air to work, but it does use an electric motor. For this customer, they had a 7.5KW blower motor.  With the inherent design of blower-type air knives, they have a reduced blowing force and turbulent air flow.  This combination required the maximum power output on the 7.5KW blower motor.
    2. Super Air Knife –With their unique design, it has one of the highest efficiencies in the market place. It can entrain 40 parts of ambient “free” air with every 1 part of compressed air.  With laminar flow and the power of compressed air, the Super Air Knives can be used at a much lower air pressure.  To compare with the electric blower motor above, the Super Air Knives would use 10KW of compressor power to operate at the highest force rating.  So, at lower air pressures, the blower motor and compressor requirement will be very similar.
  4. Noise:
    1. Blower System – With the turbulent air flow, the blower units are very loud. If operators are working near the system, they would need PPE for hearing protection, or elect to purchase (for even more money) a sound enclosure which some of the blower manufacturers offer.
    2. Super Air Knife – These units are very quiet. Even at a higher pressure, the sound level is only 72 dBA at 100 PSIG (6.9 Bar).  This level is well below the maximum noise exposure for hearing safety as marked in OSHA 29CFR 1910.95(a).
  5. Installation:
    1. Blower System –Just to begin, the installers will have to run electrical wires, controls, and ducting. The foot print is large and will need space to install.  They will have to drill holes in the floor to hold the blower in place, and perhaps build an attenuation chamber.  This can take days with no production to start operating.  And time is money.
    2. Super Air Knife –They are compact and do not take up much space. They mount easily into a system.  You can run a plastic tube or rubber hose to the Super Air Knife from a compressed air source.  If you use the Universal Mounting Kit, they will only need a 1/2″ hole for attaching.  Even if a fabricator has to make a bracket to fit into their system, the timing is in hours not days.
  6. Heat:
    1. Blower System – Besides being quite loud, blower systems get very hot as a function of the operation. While this may be sold as a benefit for some applications, it is considered a significant drawback for drying fruits and vegetables. The air can reach a target temperature of 180°F (82°C).
    2. Super Air Knife – The advantage for the Super Air Knife is the amplification ratio. The total volume of air that comes from it is 40 parts ambient and 1 part compressed air. So, the temperature of the airflow is going to be the same as the ambient environment surrounding the Super Air Knife.

The total cost of ownership is quite clear when you look at loss of output, loss of product, and breakdown of equipment.  After reviewing the information above, it was easy for them to try the model 110218SS Stainless Steel Super Air Knife Kit.  When they replaced the blower-type air knives, the customer did share some information with me.

First, they were amazed at the ease of installation and the compact design.  The customer also mentioned the amount of force that could be created by the Super Air Knife.  They were able to increase and decrease the required force to remove the liquid water from all the different fruits and vegetables.  This gave them the flexibility that they were looking for in their process.  And of course, the maintenance time and cost were eliminated.

Compressed air can be expensive, but if you use EXAIR products, you can use the compressed air very efficiently.  You do not have to sacrifice other areas within the total cost of ownership.  If you have a similar application, you can contact an Application Engineer at EXAIR.  We will be happy to discuss the benefits of using the EXAIR Super Air Knives over a blower-type air knife.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb