The FT94LT comprises a three stage heat exchanger complete with the services, controls and instrumentation required to operate
the system. The heat exchanger and control panel are mounted on top of a stainless steel table with feed pump and all services and
electrical cabinet located below.
The tubular heat exchanger design uses ten concentric 316 stainless steel tubes for product preheating (two tubes), final heating (four tubes)
and cooling (four tubes). In all cases the product passes down the inner tube and the heating/cooling medium passes through the annulus in
a counter current direction. As with all Armfield systems, it comes with hygienic fittings throughout as standard; it is easy to clean and very
flexible in use.
For the main heating, steam is applied to the service side of the heating section using an electro-pneumatic steam control valve. The product
temperature is measured at the end of the heat exchanger (or holding tube). This value is used by a Proportional, Integral and Derivative (PID)
control algorithm (implemented in the Programmable Logic Controller (PLC)), to control the steam regulating valve, hence ensuring the user
defined set point is maintained.
In order to provide a gentle preheat action, steam at sub-atmospheric pressure (and hence low temperature) is applied to the service side of
the preheat section. In this way, steam temperatures at or significantly below 100°C can be produced, and low differentials between steam
temperature and product temperature are achieved. Stable preheat temperatures of 60°C or less are feasible. Control of the steam pressure/
temperature is achieved by a manual steam control valve, and automatic PID control is an available option.
Cooling water is applied to the cooling section of the product heat exchanger via a rotameter. For applications requiring chilled exit
temperature, the system can be configured to use two initial cooling tubes using city water, and two final cooling tubes using a source
of chilled water (Armfield can provide a recirculating water chiller if required).
The system is PLC controlled, with a high resolution TFT 8”colour touch screen panel making it extremely user-friendly to configure and monitor
processing parameters. The operator is prompted at every stage whenever intervention is required.
All operation functions are controlled from this panel, including configuration and mode of operation (sterilisation, process or Clean In Place).
Different sets of processing parameters can be edited, stored and quickly recalled using the menu capability of the system.
32 distinct storage locationss included as standard.
Similarly, the ancillary items, such as the homogeniser and sterile filler, are also controlled from this panel. The system can be quickly and
easily interfaced to other free-standing Armfield process items such as a mixing vessel, a chiller or a sterile filling system.