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Quotes - Engineering - SalesMixer vessel
A CIP heater for the emulsion mixer vessel
An emulsion mixer vessel is a jacketed tank with a high-shear rotor-stator head in the bottom, a slow anchor or scraper sweep on the wall, baffles, and a vacuum dome with a sight glass and spray nozzles. Every one of those parts holds product when the batch is dropped. The rotor-stator head is the worst: the stator slots are a few millimeters wide, the emulsion in them is sheared hot and then cooled in place, and the oil phase that separates out sets into a wax plug that no spray device will reach. It is removed by recirculating hot caustic through the head with the rotor turning, which makes the shear head part of the CIP circuit and the mixer vessel a two-path circuit: spray device to the wall, pumped flow through the head.
Both paths need the same solution at the same temperature, so there is one CIP tank and one heater. The wall path is a spray device at 50–75 gpm; the head path is the circuit pump pushing 40–60 gpm through the rotor-stator and back. Together they draw 100–130 gpm from a CIP supply tank of about 1,000 gallons, and the caustic has to arrive at 170°F because the wax in the stator slots does not move until it does. This is a tank-recirculation heater sized for a fast warm-up and then for the loss through a vessel wall that is itself water-jacketed and cold.
The stator slots decide the temperature, the jacket decides the hold
A 1,000-gallon caustic tank taken from 70 to 170°F in 25 minutes is roughly 2 MBtu/h. A mixer vessel with a cold jacket then draws heat out of the wash for the whole 40 minutes, so the heater keeps working after the tank is hot.
What the mixer circuit runs at
Caustic at 2% with a surfactant, 170°F at the vessel, 40 minutes of recirculation with the shear head turning at low speed so the slots are flushed from both sides. A cosmetics plant adds the booster from its own detergent program; the heater does not care, but the plant's gaskets might, so the caustic set point is rarely pushed above 175°F. The acid step is phosphoric at 0.5–1% and 130°F on a weekly or batch-change schedule, and the rinse is softened water at 120–140°F.
The jacket is the sizing trap. A mixer vessel is jacketed for heating and cooling the batch, and when CIP starts the jacket may still hold cold tower water. A 316L wall with 50°F water on the other side pulls heat out of 170°F caustic at a steady rate for the whole wash, and a heater that was sized only to warm the CIP tank will see the vessel run 10°F below set point. Plants that can drain or warm the jacket before CIP should; the heater is sized as if they do not.
The heater for a two-path vessel
A U-tube shell-and-tube with steam in the tubes and the caustic in a 316L shell, on the CIP tank recirculation loop. For a 1,000-gallon tank brought from 70 to 170°F in 25 minutes the duty is roughly 2 MBtu/h, and we add the jacket loss on top before fixing the surface. On 50 psig steam, condensing at 298°F, the approach above 170°F is well over 120°F and the bundle is short; at 15 psig the same duty takes more surface and a larger valve, so we ask for the pressure at the heater, not the boiler.
The solution side fouls with the saponified wax that drops out when the tank cools, so the bundle is removable and the shell carries a fouling allowance of 0.001–0.002. EPDM head gasket, 150 psig at 250°F on the shell, 3/4-inch tubes for a compact bundle. Where the plant brushes rather than pulls, a straight-tube unit with removable heads is the alternative, but on wax we would rather pull the bundle and soak it than brush a cold slot.
What a mixer vessel heater quote needs
The vessel drawing tells us most of it; the jacket and the shear head tell us the rest.
- Vessel volume, jacket service, and whether the jacket is drained for CIP
- Spray device gpm and shear-head circuit gpm
- CIP tank volume and warm-up time
- Caustic strength, booster, and set point at the vessel
- Steam pressure at the heater inlet
- Connection style and finish on the CIP loop
Call and talk it through with an engineer: 1-805-484-2992
Emulsion vessel questions
It adds a second flow path and raises the temperature the plant has to hold. A spray device alone cleans a wall at 160°F, but the rotor-stator slots hold emulsion that has set, and that wax moves only at 170°F with caustic and surfactant. The extra 40–60 gpm through the head raises the circuit flow, which adds to the tank loop the heater sits on and to the loss it has to replace.
Look at the jacket. If it still holds cooling water from the batch, the vessel wall is a heat exchanger working against you, and 10°F across a 40-minute wash is a typical loss. Drain or isolate the jacket before CIP, or warm it with the jacket's own heating service, and the return climbs. If you can not, the heater needs the extra duty designed in, which is what we do when told.
It can warm the wash in the vessel, but it cannot hold a recirculating CIP tank at temperature, and it does nothing for the shear head path or the supply line. The caustic has to arrive at the spray device hot, which means the heater belongs on the CIP tank loop. Using the jacket as a helper, warming the vessel wall before the wash begins, is a sound way to cut the loss the heater must cover.
Not on this side of the tubes. The caustic is in the shell, outside the tubes, so the tube diameter affects the steam side, which stays clean. The fouling surface is the outside of the bundle, and that is cleaned by pulling the bundle and soaking it, not by passing anything through the tubes. We use 1-inch tube where a plant asks for it, at the cost of a slightly longer bundle.
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