Various Aseptic UHT Systems
Indirect Plate Sterilizer
UHT systems based on plate heat exchangers are used where the
manufacturer’s primary requirement is a dependable system for
heating liquid products at minimum operating costs. In Fig. 11.1 a
flow diagram illustrates the principle design including some of the
processing parameters.
The system can be built up to a maximum capacity of 25-30,000
l/hour.
Advantages:
• Excellent for low viscosity products
• High regenerative effect and low energy consumption
• High heat transfer area in minimal space
• Easy inspection
scraper• Low hold-up volume
• High degree of flexibility
• Variable capacity
• Large capacity plants
• Relatively low investment
• Low CIP costs
Limitations:
• Limited capability for particulates or fibers
• Exchange of gaskets required periodically
• Unsuitable for high pressure drops
• Some product degradation may occur
Products:
• Milk, flavored milk
• Fermented milk products, drinking yogurt
• Cream, coffee whiteners
• Soy milk
• Baby food
• Juice
• Coffee, tea
• Combination plants for milk, juice, coffee, tea, etc.
Indirect Tubular Sterilizer
UHT systems based on tubular heat exchangers have become
popular in many countries and are typically chosen where large
volumes of commodity products have to be processed at the
lowest possible costs.
In Fig. 12.1 a flow diagram illustrates the principle design
including some of the processing parameters.
Fig. 12.2 shows how the pressure drop affects the maximum
running hours.
In a plate based sterilizer, the increase in pressure drop is limited
to 30-40 percent. This is not a limiting factor in tubular systems,
and 16-20 hours operating time between CIP is possible. It is
also possible to operate with an intermediate cleaning each 20
hours and reduce the full CIP cycles to once a week, which
may increase the capacity by as much as 7-9 percent. Exact
times will depend on particular products and micro-biological
considerations.
Advantages:
• Less vulnerable to fouling, giving long production runs
• High operating pressures are acceptable
• Processes products with fibers and particulates
• Processes high viscosity products
• Low shear characteristics for cream
• Low requirement for gasket material and easy gasket
exchange
• Very robust design
• Low maintenance costs
• Can be designed as a multi-purpose plant
• Easy to operate
Limitations:
• Lower regenerative effect than for plate sterilizers
• Slightly higher investment costs compared with plate
sterilizers
• Higher degree of product degradation
Products:
• Milk, flavored milk
• Fermented milk products, drinking yogurt
• Cream, coffee whiteners
• Whipping cream, ice cream mix
• Evaporated milk, desserts, puddings
• Soy milk
• Coffee, tea
• Juices, juices with pulp
• Salad dressings
• Gravy, sauces, soups
• Combination plants for milk, juice, coffee, tea, etc.
Steam Infusion Sterilizer
UHT systems based on infusion heating are used where the
manufacturer wants to produce a high quality product with as little
heat degradation as possible. Also, flexibility in throughput and
variety in product range speak for an infusion based system.
In Fig. 13.1 a flow diagram illustrates the principle design
including some of the processing parameters.
The system can be supplied from 40 gal./hr. (pilot plant) to
11.624 gal./hr. with a temperature profile as shown in Fig. 13.2.

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