Revised and extended by Nick May

Transcription

1 Guideline no. 69 Guidelines for operation of continuous cookers for in-pack heat processing of foods (Reel and spiral retorts/hydrostatic retorts and pasteurisation tunnels) Revised and extended by Nick May 2012 ISBN: Station Road, Chipping Campden, Gloucestershire, GL55 6LD, UK Tel: +44(0) Fax: +44(0) Information emanating from this company is given after the exercise of all reasonable care and skill in its compilation, preparation and issue, but is provided without liability in its application and use. Legislation changes frequently. It is essential to confirm that legislation cited in this publication and current at the time of printing, is still in force before acting upon it. The information contained in this publication must not be reproduced without permission from the Publications Manager.

2 CONTENTS Page no. 1. INTRODUCTION TO THE PRINCIPLES OF HEAT PRESERVATION AND THE NEED FOR PROCESS CONTROL 1 2. GENERAL REQUIREMENTS Plant layout Steam supply to cookers Steam supply to coolers Cooling water Cooker water Instrumentation General Temperature measurement Temperature recorder controllers Pressure indicators Process timing Level control and indication Training of cooker operators and supervisors Process validation Temperature measurement inside production machines Spore reduction methods Thermal process evaluation using simulators Process deviations Safe guarding personnel and equipment Recording data Temperature drops in preheat zones Temperature drops in hold zones Temperature drops in cooling zones Stoppages Segregation of containers Informing relevant technical and management staff Deciding disposal of stock REEL AND SPIRAL COOKERS Introduction Introduction to operation of reel and spiral cooker/coolers General description Arrangement of shells Internal construction of shells 21 - iii -

3 3.3.3 Mode of agitation Speed of can rotation Plant description Reel Spiral Trough In-feed Rotary valves Atmospheric preheater shells Pressure steam steriliser shells Atmospheric cooker shells Over pressure steriliser shells Pressure cooler shells Atmospheric cooler shells Drive mechanisms Operating conditions Start up - preliminaries Start up - services Start up - recorder controllers Start up - plant checks Bringing up - process cooker shell Cooler shell - make ready for use Reel checks Measurement of cook time Instrumentation requirements specific to reel and spiral cookers Temperature measurement Temperature recorder controllers Pressure indicators Process timing Level control and indication Handling process deviations in reel and spiral cooker/coolers Validation of can rotation HYDROSTATIC COOKERS The basic principles of hydrostatic cookers Description of system Feed and discharge stations Pre-heating leg Water seal section Steam chamber Pre-cooling leg 50 - iv -

4 4.2.6 Cooling section Drying section Operating conditions Venting (saturated steam systems) Water and condensate level control Temperature Time Instrumentation specific to hydrostatic cookers Temperature Pressure Sight glasses Process timers / time in steam Handling of process deviations in hydrostatic cookers PASTEURISING TUNNELS Introduction to operation of pasteurisation tunnels General description Internal construction Modes of heating Modes of loading Modes of agitation Plant description Belt construction and maintenance Infeed/outfeed Zone segregation Drive mechanisms Pre-heat/precool zones Operating conditions Start up - preliminaries Bringing up the tunnel Measurement of cook time Instrumentation specific to pasteurisation tunnels Temperature measurement Temperature recorder controllers Process timing Water flow rates Level control and indication Handling process deviations in pasteurisation tunnels System hygiene REFERENCES 68 - v -

5 LIST OF FIGURES Figure 1: Figure 2: Figure 3: Figure 4: Figure 5a: Figure 5b: Figure 6a: Figure 6b: Figure 7: Figure 8: Figure 9: Figure 10: Figure 11: Figure 12: Figure 13 Figure 14 Figure 15: Figure 16: Figure 17: Figure 18: Figure 19: Full diameter reel and spiral cooker simulators Hydrostat simulator A reel and spiral retort system (5 shell) Typical shell arrangements Schematic of transfer valve operation principle Molenaar's "soft" in feed Schematic of transfer valve operation principle Schematic of clearance of cans between rails Dual feed system Schematic showing the zone of fast axial rotation (FAR) in a reel and spiral shell Schematic of seals on a transfer valve Ellab can rotation counter mounted in a can Can rotation data (total count v time) Schematic diagram of hydrostatic cooker (single pass) Schematic diagram of hydrostatic cooker (multi pass with combined steam and water chamber ) Schematic diagram of hydrostatic cooker with separated steam chamber Example heating profile from a hydrostatic cooker Schematics of the main heating principles of tunnel pasteurisers Engineering drawing of a sprayed water tunnel pasteuriser (Molenaar) A water immersion pasteurisation tunnel with planetary motion for processing cartons Typical belt arrangement and dead plate - vi -