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Quotes - Engineering - SalesLiquid egg
The caustic heater that keeps an egg pasteurizer running
Liquid egg is pasteurized gently, around 140°F for whole egg and a little lower for white, because albumen begins to coagulate not far above that. The same sensitivity is what fouls the line. Egg protein denatures on the hot plates of the pasteurizer's heating section and sets into a film within hours, and the regeneration section downstream collects it too. Egg plants therefore wash the pasteurizer every 4–8 hours of production, far more often than a dairy pasteurizer, and the CIP heater is sized by how fast it can turn the tank around between runs, not by one long nightly wash.
The chemistry is a protein wash: sodium hydroxide at 1.5% and 160–165°F for 20–30 minutes lifts the denatured albumen, and because egg carries phosphate and the water carries calcium, an acid step at 1% phosphoric and 130°F runs on most cycles to clear the mineral the caustic exposes. The loop is treated as sanitary, with tri-clamp connections and a drainable layout, and sanitize water is held at 180°F at the return.
A 1,000-gallon caustic tank that comes back from a wash at 120°F has to be at 165°F again in about 15 minutes to meet the next cycle. That is roughly 1.5 MBtu/h, and it recurs several times a shift.
A warm 1,000-gallon tank back to 165°F in 15 minutes, repeatedly
Egg lines never heat the caustic from cold during production; they reheat a tank that lost 45°F to the last wash. The heater is sized for that 1.5 MBtu/h recovery and for the duty cycle, so it runs more hours a day than most CIP heaters.
The circuit: albumen film, phosphate scale, every few hours
Denatured egg protein is a tenacious soil because it bonds to the stainless as it sets and traps fat and mineral beneath it. Caustic at 1.5% and 165°F swells and peptizes the film; below 155°F the wash runs long and the plates still show a haze under the light. The soil comes back to the CIP tank in solution and as fine flocs, and the tank loop pump carries both into the heater, where the hottest surface in the loop is the shell side.
Egg yolk adds phospholipid and calcium phosphate, so the acid step is nearly as regular as the caustic. Phosphoric at 1% and 130°F for 10–15 minutes keeps the heating section clear. Nitric is uncommon in egg plants, and when it is used the heater's solution-side gasket should be FKM rather than EPDM.
The heater: a sanitary U-tube built to cycle
A U-tube shell-and-tube with steam inside the tubes and caustic on the shell side is the right construction for an egg plant tank loop. The U-bundle expands freely as the heater goes from idle to 165°F and back a dozen times a day, the protein film forms on the shell side where the bundle can be pulled to clear it, and steam at 50 psig in the tubes gives 298°F and a compact bundle for 1.5 MBtu/h. Shell, bundle and heads are 316L with tri-clamp connections, a low-point drain and a 32 Ra solution side where the plant's program asks for it.
Because the duty cycle is so frequent, the steam control valve and trap see more operations in a month than a brewery heater sees in a year. Specify them for modulating service, and let us know the lowest tank temperature the schedule ever produces so the valve can turn down to a hold without hunting.
What to send for an egg line heater
An egg plant quote hinges on turnaround. Tell us how long the tank has between washes and what temperature it comes back at, and the rest of the sizing follows.
- Caustic tank gallons, return temperature after a wash and time to the next cycle
- Caustic strength and the wash temperature your program specifies
- Acid used, strength and how often it runs
- Tank loop pump flow in gpm
- Steam pressure at the CIP room
- Finish, drainability and 3-A requirements for the loop
- Full heater or a replacement bundle for the one you have
Call and talk it through with an engineer: 1-805-484-2992
Liquid egg questions
Check the temperature at the pasteurizer, not at the tank. If caustic leaves the tank at 165°F and reaches the plates at 150°F, the heater is keeping the tank warm but not making up what the line and the cold regeneration section absorb during the wash. A heater sized for the recirculating loss as well as the heat-up fixes it; so does raising the set point 5°F.
Because an egg line washes during the shift, between pasteurizer runs, and every minute the tank spends heating is a minute the pasteurizer is not running product. A 1,000-gallon tank reheated 45°F in 15 minutes needs about 1.5 MBtu/h; the same tank over 60 minutes needs a quarter of that but costs 45 minutes of production several times a day.
The heater never touches egg, so most inspectors accept it as utility equiptment in 316L with tri-clamp ends and a drainable shell. Some egg plants run their programs as if the CIP loop were product contact, and then we build the solution side to 32 Ra with a 3-A symbol on the heads. Ask your inspector first; it is a build choice, not a redesign.
Not a U-tube. The bundle floats on one end and takes the expansion of every heat-up without stressing a tubesheet joint, and there are no gaskets in the steam path to fatigue. The parts that feel the cycles are the control valve, trap and the solution-side head gasket, which we specify for the duty. Plan on inspecting the gasket when the bundle is pulled for protein film.
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