US-20260123635-A1 - SPIRAL CONVEYOR THERMAL PROCESSING SYSTEM

US20260123635A1US 20260123635 A1US20260123635 A1US 20260123635A1US-20260123635-A1

Abstract

The conveyor belt ( 24 ) of an oven system and apparatus ( 20 ) is configured into ascending and descending spiral stacks ( 26 ) and ( 28 ) to define a central cylindrical channel ( 62 ). A pair of upper and lower fans ( 130 ) and ( 132 ) are positioned within the central cylindrical channel ( 62 ) to circulate thermal processing fluid in upper and lower circuits vertically through the spiral stacks and also laterally toward the inlet of the fans ( 130 ) and ( 132 ) to set up upper and lower thermal processing zones in the spiral stacks and circulation routes for the cooking medium through the spiral stacks.

Inventors

Owen Eugene Morey
Ramesh M. Gunawardena

Assignees

JBT MAREL CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251106

Claims (20)

1 . A thermal processing apparatus, comprising: (a) a thermal processing chamber having an inlet and an outlet; (b) a spiral conveyor configured in at least one spiral stack within the thermal processing chamber, the spiral stack defining a central channel relative to the stack, the conveyor entering the thermal processing chamber via the chamber inlet and exiting the thermal processing chamber via the chamber outlet; and (c) a pair of spaced-apart circulation fans disposed within the central channel of the spiral conveyor stack comprising an upper fan located within the central channel at an elevation below the top of the spiral stack and a lower fan located within the central channel at an elevation above the bottom of the spiral stack, the upper fan operating to direct thermal processing medium to flow upwards through and out the central channel and the lower fan operating to direct the thermal processing medium downwards through and out the central channel; (d) a thermal processing medium supply for supplying thermal processing medium to the thermal processing chamber, the thermal processing medium supply comprises a heat exchanger positioned within the central channel of the at least one spiral stack; and (e) the thermal processing chamber is configured to route the thermal processing medium flowing upwardly through and out the central channel of the spiral stack laterally across the top of the spiral conveyor and then directly back downwardly through the spiral stack across the width of the spiral stack without encountering a restriction to the flow of the thermal processing medium from an apparatus to thermally process the thermal processing medium, and to route the thermal processing medium flowing downwardly through and out the central channel of the spiral stack laterally across the bottom of the spiral conveyor and then directly back upwardly through the spiral stack across the width of the spiral stack without encountering a restriction to the flow of the thermal processing medium from an apparatus to thermally process the thermal processing medium such that the thermal processing medium flowing downwardly through the spiral stack meets the thermal processing medium flowing upwardly through the spiral stack and causes said downwardly and upwardly flowing thermal processing medium to flow inwardly toward and into the central channel to complete upper and lower circulation paths of the thermal processing medium.
2 . (canceled)
3 . The thermal processing apparatus according to claim 1 , wherein the distance separating the circulation fans can be varied.
4 . The thermal processing apparatus according to claim 1 , wherein the elevation of the circulation fans relative to the spiral stack can be adjusted.
5 . The thermal processing apparatus according to claim 1 , further comprising a mezzanine disposed between the circulation fans.
6 . The thermal processing apparatus according to claim 1 , wherein the circulation fans comprise propellers.
7 . The thermal processing apparatus according to claim 6 , wherein the propeller of the upper fan has an opposite pitch to the propeller of the lower fan.
8 . The thermal processing apparatus according to claim 6 , wherein the circulation fans are coupled together.
9 - 13 . (canceled)
14 . The thermal processing apparatus according to claim 1 , wherein the spiral conveyor is configured in at least two spiral stacks within the thermal processing chamber.
15 . (canceled)
16 . The thermal processing apparatus according to claim 1 , wherein the thermal processing medium discharged by the thermal processing medium supply to the thermal processing chamber is heated air.
17 . The thermal processing apparatus according to claim 16 , wherein the heated air is supplied to the inlet of the circulation fans.
18 . (canceled)
19 . The thermal processing apparatus according to claim 1 , further comprising an ambient air supply.
20 . The thermal processing apparatus according to claim 1 , further comprising an exhaust system to exhaust the thermal processing medium from the thermal processing chamber.
21 . The thermal processing apparatus according to claim 1 , further comprising a control system to control the supply of thermal processing medium to the thermal processing chamber and to control the operation of the circulation fans.
22 - 39 . (canceled)
40 . The thermal processing apparatus according to claim 1 , wherein the thermal processing chamber is configured to direct the thermal processing medium flowing downwardly through the spiral stack toward the central channel at an intermediate elevation of the spiral stack and direct the thermal processing medium flowing upwardly through the spiral stack toward the central channel at an intermediate elevation of the spiral stack.
41 . A thermal processing apparatus, comprising: (a) a thermal processing chamber having an inlet and an outlet; (b) a spiral conveyor configured in at least one upright spiral stack within the thermal processing chamber, the spiral stack defining a central channel relative to the stack around which the spiral stack travels, the conveyor entering the thermal processing chamber via the chamber inlet and exiting the thermal processing chamber via the chamber outlet; (c) a pair of spaced apart circulation fans both disposed within the central channel of the spiral stack, comprising an upper fan located at an elevation below the top of the spiral stack and a lower fan located at an elevation above the bottom of the spiral stack, the fans operating to direct thermal processing medium relative to the spiral stack, wherein the upper circulation fan directs the thermal processing medium to flow upwards through and out the central channel and the lower circulation fan directs the thermal processing medium downwards through and out the central channel; (d) a thermal processing medium supply for discharging thermal processing medium into the thermal processing chamber, the thermal processing medium supply comprises a heat exchanger positioned within the central channel of the at least one spiral stack; and (e) further comprising thermal processing medium flow direction means to route the thermal processing medium flowing upwardly through and out the central channel of the spiral stack and then laterally across the top of the spiral conveyor and then directly back downwardly through the spiral stack without any physical impediment to the flow of the thermal processing medium caused by an apparatus for thermally processing the thermal processing medium, and to route the thermal processing medium flowing downwardly through and out the central channel of the spiral stack and then laterally across the bottom of the spiral conveyor and then directly upwardly into and through the spiral stack without any physical impediment to the flow of the thermal processing medium caused by an apparatus for thermally processing the thermal processing medium such that the thermal processing medium flowing downwardly through the spiral stack meets the thermal processing medium flowing upwardly through the spiral stack and causes said downwardly and upwardly flowing thermal processing medium to flow inwardly toward and into the central channel to complete upper and lower circulation paths of the thermal processing medium.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of U.S. patent application Ser. No. 15/418,519, filed Jan. 27, 2017 (now U.S. Pat. No. 12,465,052), the entire contents of which are incorporated herein by reference. BACKGROUND Spiral conveyor-based thermal processing systems include a cooking surface or a cooling/freezing surface in the form of a pervious conveyor belt for conveying workpieces, including food, through a thermal processing chamber in a spiral or helical path. If the workpiece is being cooked or otherwise heated, a heat source, such as steam, air, or mixtures thereof, is provided within or adjacent the cooking chamber for cooking the workpieces. Correspondingly, if thermal processing is in the form of cooling or freezing, then a source of cooling medium is provided either within the cooling/freezing chamber or adjacent thereto. An advantage of thermal processing systems utilizing spiral conveyor belts is that a relatively long processing path can be achieved with a small footprint. For example, a 600-foot-long thermal processing conveyor belt in a spiral configuration can be contained within a 20-foot×20-foot×20-foot housing. However, spiral stack conveyor thermal processing systems do have inherent drawbacks from a linear oven of a comparable length. In a linear oven, the upper and lower surfaces of the products are exposed to being efficiently impinged upon by the thermal processing medium. However, in a spiral oven, the workpiece is not as directly accessible to the thermal processing medium since the work products are arranged in stacked layers, thus requiring less direct thermal processing methods than direct impingement of the thermal processing medium onto the food product. In one spiral stack conveyor, a fan system is used to direct the flow of the thermal processing medium in the form of 100% steam or air or a mixture of steam and air vertically through the annulus of the spiral conveyor, either in the upward or downward direction, as well as to some extent horizontally across the layers of the spiral stack. One difficulty in this type of thermal processing medium flow arrangement is to achieve uniform thermal processing across the conveyor since typically the food product is arranged in multiple lanes with variable spacing along the conveyor. When the conveyor belt is in straight configuration, the food products can be fairly uniformly spaced across and along the conveyor. However, when the conveyor curves into a spiral, the food products on the inside of the conveyor become relatively closer together, whereas the food products on the outside of the conveyor become relatively further apart. As such, the food products on the inside of the conveyor tend to receive less thermal processing medium per food product relative to the food products located on the outside of the conveyor. As such, attempts have been made to direct at least some of the thermal processing medium across the levels or flights or tiers of the conveyor, typically from the outside toward the center of the spiral. Other techniques that have been employed in an effort to more uniformly thermally treat food products in a spiral stack conveyor include reversing the direction of flow of the thermal treatment medium while the food product is moving along the spiral conveyor. For example, during part of the processing cycle, the thermal processing medium may be directed upwardly through the annulus of the spiral, and then later in the cooking process, the direction of flow of the thermal processing medium may be reversed to flow from the top of the conveyor stack down. Another effort in achieving more uniform thermal processing is to employ baffles or mezzanines around and/or within the center of the spiral conveyor to control the direction of the thermal processing medium flow through the spiral stack. In this regard, fixed inner mezzanines have been positioned with the center of the spiral stack to essentially divide the spiral stack into two different thermal processing zones. For example, a first thermal processing zone may be at a higher pressure, and a second thermal processing zone may be at a lower pressure. The heat transfer between the thermal processing medium and the workpiece primarily occurs either by condensation heat transfer or convection heat transfer. In a cooking situation, condensation heat transfer is more efficient when the surface temperature of the workpiece is below the dew point temperature of the cooking medium, for example, steam or a steam-air mixture. Convection heat transfer is typically used to finish when the temperature of the workpiece rises above the dew point temperature and also to develop color and to brown the workpiece. A further effort to achieve more uniform and effective thermal treatment of food products is to employ tubes or nozzles that extend laterally between layers or tiers of the spiral stack, and thereby direct the thermal processing medium downwa