A thermal treatment system and method

Abstract

A system and method for the thermal treatment or blanching of food product. The system comprises a horizontally rotatable auger with perforated flights to convey the product from and a supply side to discharge, enveloped by a cylindrical body partially filled with water, guaranteeing entire submersion the product. A first part of the auger is supplied with hot water at first temperature and discharges water from the cylindrical body near the product inlet side of the auger. A second part of the auger is supplied with hot water at a second temperature and discharges water from the cylindrical body near the product outlet side of the auger. It has been found that in this way a compact and cleanable rotary screw type thermal treatment or blanching system is provided, with two successive zones providing optimal process controllability, the ability of low temperature energy reclaim, minimization of the use of fresh make-up water and minimal product damage.

Description

[0001] Title: A thermal treatment system and method

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a thermal treatment system and corresponding method, for example for blanching of food products, such as e.g. fruits, vegetables or potatoes.

[0004] BACKGROUND TO THE INVENTION

[0005] Blanching is a thermal treatment process of food products such as fruits, vegetables or potatoes, whereby the product is subjected to warm water or steam for one or more well defined respective durations to one or more well defined elevated temperatures with the purpose to, for example, inactivate enzymes, modify the product texture, preserve colour, improve flavour or nutritional values or to remove trapped air. The blanching process usually precedes one or more other unit operations, such as cooling and / or cooking and / or freezing and / or frying and / or drying.

[0006] An example of a blanching process of green vegetables is described in EPO 124627. The herein described stepwise blanching process is characterized by a first step of relatively short duration (1 to 30 sec) during which the products are exposed to a relatively high temperature (90 to 100°C), followed by a second step of longer duration (1 to 60 min) with lower temperature (45 to 90°C). Certain products might preferably be exposed to a third blanching step. The combination of these specific steps appears to improve the firmness, texture and / or colour of the products after a certain period of frozen storage, approaching the quality of the fresh raw materials.

[0007] The blanching of potatoes usually serves to deactivate enzymes, leach of sugars and / or improve quality aspects of the final product such as for example swelling power, water solubility, stability during frying, colour and / or digestibility. The temperature of potato blanching processes ranges typically from 70 to 90°C, with a residence time ranging from typically 15 to 35 min. The blanching of potatoes commences with the hydration of cells as the product temperature increases, followed by the melting of crystals, arrangement of starch chains from ordered to disordered and the separation of amylose and amylopectin, the so-called gelatinization process. The blanching process of potatoes is usually followed by a cooling process, whereby the starch chains realign, reorder and form interconnecting hydrogen bonds, the so-called retrogradation process. This process takes typically 15 minutes or longer and is completed when the core temperature of the product has decreased ideally to 12°C. The temperature evolutions and durations of the respective blanching and cooling processes, i.e. the gelatinization and retrogradation processes, can have substantial influence on one or more of the aforementioned quality aspects of the final potato product.

[0008] Industrial blanching processes usually make use of either a belt or a screw to convey the product.

[0009] In case of a belt conveyor, the product is distributed to a certain layer thickness on top of a water permeable conveying belt. Multiple sprayers are mounted inside the blancher above the product and belt to supply water of a certain temperature to the product layer. After passing through the product layer and belt, the water is collected in a water collection tank underneath the belt, after which a part of the collected water is pressurized again by a pump, reheated in a heat exchanger or by direct steam injection and returned to the sprayers. Another part of the water might be drained from the collection tank, to be replaced by a similar amount of fresh make-up water, in order to maintain the concentrations of into the blanching water dissolved matters, such as for example leached of sugars, below a certain maximum. The installation of multiple successive collection tanks, pumps, heaters and sprayers permits to expose the product on the belt to a predefined temperature evolution throughout the blanching process. As described above, such process controllability is in some cases essential to attain optimal product quality. Furthermore, multiple of such successive compartments permits the reuse of drained water from compartments with relatively low concentrations of dissolved matters as make-up of compartments with relatively high concentrations, in order to limit the consumption of fresh make-up water for the blanching process.

[0010] Blanching processes typically require a lot of energy for heating up the entire product mass, from a relatively low supply temperature to a relatively high temperature required for the blanching process. An advantage of belt blanchers is that compartments which require lower blanching temperatures might be heated with excess heat from other processes released at slightly higher temperatures.

[0011] Another advantage of belt blanchers is that products on the belt are not exposed to any mechanical stresses. Such blanchers are therefore especially advantageous for vulnerable products, which are relatively sensitive to mechanical abuse.

[0012] Belt blanchers hence seem to offer certain advantages, particularly in view of process controllability, the ability of low temperature energy reclaim, minimization of the use of fresh make-up water and minimal product damage.

[0013] A disadvantage of belt blanchers is that the periodical cleaning process is relatively complex and labour intensive. Also, belt blanchers typically require a relatively large footprint in the process area.

[0014] Rotary screw blanchers offer advantages over belt blanchers in view of compactness and cleanability. A rotary screw blancher applies a horizontal rotatable auger to convey the product from the entrance side to the outlet of the blancher. The residence time of the product in the blancher is then determined by a combination of the rotational speed of the auger and the pitch of the screw. A rotary screw blancher further comprises a cylindrical body which partially envelops the auger, at least for the lower part. This cylindrical body is partially filled with water, to a level at least exceeding that of the to be blanched product, guaranteeing entire submersion the product. The gaps between the flights of the auger and the enveloping cylindrical body are usually not more than 5 to 10 mm, large enough to provide sufficient clearance for the rotational movement of the auger on the one hand and small enough to prevent product from getting stuck inside the gaps on the other hand.

[0015] Hot water is usually supplied via multiple orifices near the lowest point of the cylindrical body at various locations along the length of the auger. According to US3642495 this method provides an even rate of heat transfer from the water to the product. Also, the upwardly directed flow provides some agitation of the product layer, helping to leach of or wash away sugars from the product surfaces. After passing through the product layer, the water can be discharged laterally with respect to the transport direction of the product, via an overflow at left and right side to discharge compartments at the sides of the cylindrical body. From there, the water can be collected, partially discharged, mixed with fresh make-up water, pressurised, reheated directly by steam or indirectly via a heat exchanger and injected again via the injection nozzles to the blancher. It is also possible that the injected water is transported along with the product towards the product outlet side of the blancher. The water has in that case not necessarily the same longitudinal transport velocity as the product, but usually a higher velocity. In such cases, the water passes the flights of the auger via perforations in the surfaces of these flights. Such higher velocities of the water as compared to that of the product is usually applied for two reasons: The product is entrained along with the water in forward direction rather than being pushed forwardly by the flights of the auger avoiding product damage by contact with the flights. Also, high flow rates of water limit temperature differences inside the blancher, guaranteeing uniform water temperatures throughout the whole thermal treatment process.

[0016] Unlike belt blanchers, screw type blanchers hence consist of single blanching compartment only, with a single temperature level for the entire process heat demand and a single water quality for the whole blanching process. This characteristic aspect of screw blanchers limits their process controllability, the ability of low temperature energy reclaim and the option to discharge and supply water at those parts of the process where most sugars are leached of or dissolved.

[0017] US5752431 describes a screw conveyor consisting of a blancher and two cooling sections in one common cylindrical body. In fact, this screw conveyer consists of three successive zones, each with its own temperature and water supply and discharge. The three successive zone are here separated by two dividing baffle plates, a plate welded transversely inside the cylindrical body separating the water volumes of the three successive zones. The helical flight on the screw conveyer is interrupted before and after these baffle plates. Furthermore means are foreseen to transport the product from one zone to the next zone by lifting the product out of the water near the end of a zone, drop it on an inclined plate above the dividing baffle so that the product slides off the plate towards the beginning of the next zone. In principle, the two cooling sections could also serve as blanching sections, each with their own temperature and water quality, with optional re-use of water drained from one section into another.

[0018] A disadvantage of this construction is, however, that the transport of product from one section to the next (i.e. the repeated lifting from the product out of the water) is accompanied with a lot of extra product handling, stresses and consequential damaging, which does not occur in single compartment blanchers. Furthermore, the location of the dividing baffles is fixed. Therefore, the flexibility of the described system to accommodate to different products requiring different thermal treatments is limited. After all, the described ‘multi compartment’ system in a common cylindrical body does not have any significant advantages above two or more successive standard ‘single compartment’ rotary screw blanchers or to a belt blancher. SUMMARY OF THE INVENTION

[0019] It is an object to provide an improved thermal treatment system. According to an aspect an aim is to provide a rotary screw type thermal treatment system for the blanching of food products, and / or a method for blanching of food products, that obviates, or at least diminishes the disadvantages mentioned above for rotary screw and belt blanchers. More in general, it is an object to provide a compact and cleanable thermal treatment system and method with optimal process controllability, the ability of low temperature energy reclaim, the minimization of the use of fresh make-up treatment liquid (in particular water) and minimal product damage. Also, an object is to provide optimum food product treatment (leading to improved food product).

[0020] Thereto, according to a first aspect is provided thermal treatment (e.g. blanching) system that is defined by the features of claim 1.

[0021] Advantageously, there is provided a thermal treatment system, comprising a treatment chamber having a product inlet for receiving product to be treated and a product outlet for discharging the product, wherein the treatment chamber includes a horizontal rotatable auger to convey the product in a product flow direction from the product inlet to the product outlet, wherein the treatment chamber has at least one liquid supply port for feeding thermal treatment liquid into the chamber, wherein the treatment chamber has at least one first liquid discharge port for discharging treatment liquid from the chamber, the first discharge port being located upstream with respect to the at least one supply port, viewed relative to said product flow direction, for example near the product inlet, wherein the treatment chamber has at least one second liquid discharge port for discharging treatment liquid from the chamber, the second discharge port being located downstream with respect to the at least one supply port, viewed relative to said product flow direction, for example near the product outlet. It has been found that in this way a compact and cleanable rotary screw type thermal treatment (e.g. blanching) system can be provided. The innovative system configuration can provide two successive treatment zones in the chamber (e.g. a first zone and a second zone), each e.g. providing distinct treatment temperature and liquid quality, which provides optimal process controllability. Also, this can provide the ability of low temperature energy reclaim, as well as minimization of the use of fresh make-up liquid and minimal product damage.

[0022] The auger (in particular the flight of the auger) is preferably uninterrupted, viewed along a longitudinal direction of the chamber, that is: the auger flight preferably extends (continuously) through the successive treatment zones between the product entry and exit (e.g. along the at least one liquid supply port), and preferably does not contain axially spaced-apart auger sections. Also, it follows that preferably the auger does not have multiple lifting flights, and product is not lifted by the auger during transport between the successive treatment zones. Thus it is preferred that the product remains in the treatment liquid (i.e. at and / or below a respective liquid level), and / or in -other words- the product follows a generally horizontal path from the product inlet to the product outlet (and during transport between successive treatment zone), during system operation. In addition, it follows that according to a preferred embodiment the two successive treatment zones are not divided by a baffle (or similar dividing element); or in other words, the two successive treatment zones are in direct treatment liquid contact (allowing product to pass in a submerged manner from a first treatment zone to a second treatment zone or vice-versa).

[0023] The system can include one or more of the following features:

[0024] - a product inlet for receiving fresh product;

[0025] -a horizontal rotatable auger to convey the product from the entrance side to the outlet of the treatment chamber;

[0026] - a product outlet for discharging the treated product; - a drive motor for rotational movement of the auger; a residence time of the product in the chamber is preferably determined by a combination of the rotational speed of the auger and the pitch of the screw;

[0027] - perforations is the flights of the auger; preferably, the arrangement of the flight perforations (e.g. a perforation quantity and hole diameter) is such that it avoids product to be damaged thereby and large enough for a longitudinal liquid flow to pass therethrough without substantial liquid level differences between neighboring compartments of the auger;

[0028] - the treatment chamber can be a cylindrical body which (partially) envelops the auger, at least for the lower part; during operation, the chamber can e.g. be partially filled with treatment liquid, to a the level at least exceeding that of the to be treated (e.g. blanched) product, guaranteeing the entire submersion the product;

[0029] - preferably gaps between flights of the auger and a circumferential inner surface of the treatment chamber (e.g. the cylindrical body enveloping it) are at most 1 cm, for example in the range of 5 to 10 mm, which is large enough to provide sufficient clearance for the rotational movement of the auger on the one hand and small enough to prevent product from getting stuck inside the gaps on the other hand;

[0030] - the at least one supply port can include a number of liquid inlet nozzles, e.g. located near a bottom of the treatment chamber (e.g. the cylindrical body), preferably at various locations along a length of chamber; in that case it is preferred that one common manifold is provided that is connected to each of the supply ports (or nozzles); for example, such a manifold can be provided with or associated with one more manual or automatic valves (e.g. in a common water inlet) for controlling / adjusting liquid flow into the manifold and / or from the manifold to the supply port(s);

[0031] - preferably, one or more manual or automatic valves are provided for controlling liquid flow (e.g. flow rate) to each of the one or more inlet ports; it will be appreciated that such valve means can be provided in some or all of supply lines to the inlet port(s); - a first water discharge from the chamber near a product inlet side of the chamber;

[0032] - a second water discharge from the chamber near a product outlet side of the chamber;

[0033] - a first circulation pump (e.g. first injection pump), pressurizing liquid from the first liquid discharge port to the one or more liquid supply ports (e.g. injection nozzles);

[0034] - a second circulation pump (e.g. second injection pump), pressurizing liquid from the second discharge port to the one or more liquid supply ports;

[0035] - a first heating device, for directly or indirectly heating the liquid received from the first circulation pump to a first temperature setpoint; the first heating device can e.g. be arranged between the first circulation pump and an aforementioned manifold;

[0036] - a second heating device, for directly or indirectly heating the liquid from the second circulation pump to a second temperature setpoint; the second heating device can e.g. be arranged between the second circulation pump and an aforementioned manifold;

[0037] - a first water overflow located near a product inlet side of the treatment chamber;

[0038] - a second water overflow located near a product outlet side of the treatment chamber;

[0039] - a first fresh liquid make-up to the inlet of a said first circulation pump; and / or

[0040] - a second fresh liquid make-up to the inlet of a said second circulation pump.

[0041] According to a preferred embodiment, the treatment liquid is water.

[0042] According to an embodiment, a said first zone is located near a product inlet side of the auger and a said second zone near a product discharge side. According to a preferred embodiment, during operation, the first zone can receive liquid from a first circulation pump, preferably via a manifold, and e.g. a first heating device via one or more first ports of the supply ports (e.g. via first injection nozzles at the bottom of the chamber). Preferably, the second zone can receive liquid from the second circulation pump (also preferably via a manifold) and e.g. a second heating device via one or more second ports of the supply ports (e.g. via second the injection nozzles at the bottom of the chamber). It is preferred that a location of a vertical imaginary interface (boundary) between the first and the second zone is located at a point between the inlet side and outlet side of the auger (i.e. between an axial first and axial second end of the auger), for example at a point where a valve in a common liquid inlet manifold (if any) is closed, whereas other valves in the common water inlet manifold can be open.

[0043] According to a preferred embodiment, during operation, said first treatment zone can mainly serve for heating up the product, from a relatively low inlet temperature to a first, higher temperature. It is preferred that a longitudinal component of a liquid flow direction in the first zone is opposite to the product flow direction (i.e. transport direction) of the product through the treatment chamber (and the respective first zone). This counterflow of liquid and product is beneficial, firstly for efficient heat transfer from the relatively warm liquid to the colder product and secondly to leach of or dissolve sugars from the fresh product surfaces (in case the product surfaces contain sugars).

[0044] The second zone can mainly serve for retaining the product at a more or less constant high, second temperature, for example for blanching the product, for example to gelatinize the starch in potatoes at for example 70 to 90°C (in case the product consists of potatoes).

[0045] A heat demand of the first zone can generally be relatively high as compared to a heat demand of the second zone, but typically requires a lower heat supply temperature in case this high heat demand is supplied indirectly, e.g. via a heat exchanger. A heat demand of the second zone, with can provide a more or less constant product temperature, can be generally lower than the heat demand of the first zone, but can require heat supply at somewhat higher temperature in case of indirect heating of recirculating liquid.

[0046] Preferably a longitudinal component of the liquid flow direction in the second zone is parallel to the flow direction of the product through the chamber and through that zone. Moreover, it is preferred that the longitudinal component of the liquid flow in the second zone is larger than the longitudinal component of the product flow through that zone. This is beneficial for entrainment of the product away from surfaces of flights of the auger, minimizing propulsive forces from auger to product and therefore minimizing stresses to the product and consequential damage.

[0047] According to an embodiment, during operation, a rate at which soluble matters are released from the product surfaces to the treatment liquid (e.g. water), such as by leaching of or dissolving of sugars, can be higher at the start of the treatment process, i.e. in the (counterflow) first zone.

[0048] Preferably a supply of fresh treatment liquid to this first zone and an associated overflow (if any) of liquid from this first zone can be adapted to a possible high initial rate of release of soluble matters from product in the first zone. According to an embodiment, this can be carried out, for example, independently of a fresh supply of liquid to the second zone and overflow (if any) of liquid from of the second zone, in particular in case a flow rate of liquid across a vertical imaginary interface between the first and the second zone is negligible or zero.

[0049] The invention also provides a method for the thermal treatment, for example blanching, of food products such as e.g. vegetables or potatoes, the method for example utilizing a system according to the invention.

[0050] Advantageously, the thermal treatment method includes:

[0051] -feeding treatment liquid into a treatment chamber, containing a rotating horizontal auger, via at least one liquid supply port;

[0052] -feeding product into the treatment chamber via a product inlet; -transporting the product, in a product flow direction, from the product inlet to a product outlet, at least partly by the rotating auger (, and subsequently removing the product from the treatment chamber);

[0053] -discharging treatment liquid upstream of said at least one liquid supply port (i.e. upstream with respect to a product flow / transport direction through the chamber, and during the supply of liquid via said supply port) via at least one first liquid discharge port; and

[0054] -discharging treatment liquid downstream of at least one liquid supply port (i.e. downstream with respect to the product flow / transport direction through the chamber, and during the supply of liquid via said supply port) via at least one second liquid discharge port.

[0055] In this way, above-mentioned advantages can be achieved. According to further embodiments, the method preferably comprises one or more of the following features: submersion of the to be treated product in and transport through the treatment liquid in the treatment chamber during a certain (well defined) treatment time;

[0056] - Whereby this treatment time preferably consists of a first interval and a second interval;

[0057] Whereby during the first interval the product can be exposed to a first liquid circulation (e.g. in an afore-mentioned first treatment zone), for example at a first temperature and a first liquid quality, in counterflow with the main direction of transport (flow direction) of the product;

[0058] Whereby during the second interval the product is exposed to a second liquid circulation (e.g. in an afore -mentioned second treatment zone), for example at a second temperature and a second liquid quality, having a parallel flow to the main direction of transport of the product; The relative duration of the first and second interval as portions of the treatment time can preferably be selected or adjusted, for example it can be more or less freely chosen;

[0059] The first treatment zone is preferably separated from the second treatment zone through a vertical imaginary interface; and / or The liquid flow across this vertical interface, i.e. from the first zone to the second zone or vice versa is preferably negligible or even zero.

[0060] Further advantageous aspects of the invention are described in the dependent claims.

[0061] It will be appreciated that any of the aspects, features and options described in view of a resulting dual zone thermal treatment system apply equally to the method for dual zone thermal treatment system, and vice versa. It will also be clear that any one or more of the above aspects, features and options can be combined.

[0062] BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Non-limiting embodiments of the present invention will now be described in detail with reference to the accompanying drawings in which:

[0064] Figure 1A shows a schematic representation of a typical screw blancher according to the present state of the art, seen from a side (view 1A- lA of Fig. IB);

[0065] Figure IB shows a schematic representation of the screw blancher of Fig. 1A, seen from a front (view IB- IB of Fig. 1A);

[0066] Figure 1C shows a detail of Fig. 1A, of an auger of the system;

[0067] Figure 2A shows a schematic representation of an example of a screw type thermal treatment system according to the present invention, seen from the side (view 2A-2A of Fig. 2B);

[0068] Figure 2B shows a schematic representation of the example of Fig. 2A seen from a front (view 2B-2B of Fig. 2A); Figure 3 shows an example of a typical temperature evolution of a potato blanching process inside the screw blancher from Figure 1; and

[0069] Figure.4 shows an example of a possible temperature evolution of a potato blanching process inside the thermal treatment system from Figure 2.

[0070] DETAILED DESCRIPTION

[0071] In the drawings, similar or corresponding features are denoted by similar or corresponding reference signs. Also, in the following, water is mentioned as treatment liquid, in particular for blanching a foodproduct. The skilled person will appreciate that a different liquid can also be used as treatment liquid.

[0072] Figure 1 (i.e. Figures 1A, IB) shows an illustration of a screw blanching system according to the present state of the art, which has some disadvantages which the present invention seeks to alleviate. The rotary screw blancher 1 applies a horizontal rotatable auger 2 (having a helicoid flight or screw) to convey the product 3 from a product entrance 4 to a product discharge (outlet) 5 of the blancher. The residence time of the product in the blancher is determined by a combination of the rotational speed of the drive motor 6 connected to a shaft 7 of the auger 2 and a pitch 8 of the respective helical screw. The rotary screw blancher further comprises a chamber, in particular a cylindrical body 9, which partially envelops the auger 2, at least for the lower part. Multiple hinged access doors 10 can be located at the top side of the cylindrical body 9 for inspection, service and cleaning of the inner parts of the blancher. The cylindrical body 9 is partially filled with water, to a the level 11 usually slightly (0 to 400 mm) above a centerline 20 of the shaft 7 and at least exceeding that of the level to be blanched product, guaranteeing entire submersion the product in the water volume inside the body. The gap between the flights of the auger and the cylindrical body around it is usually not more than 5 to 10 mm, large enough to provide sufficient clearance for the rotational movement of the auger on the one hand and small enough to prevent product from getting stuck inside the gaps on the other hand. The flights of the auger are foreseen with perforations 12 (see Fig. 1C), allowing the water to pass these flights at a longitudinal velocity different, usually higher, than that of the product.

[0073] Hot water is usually supplied through multiple inlet ports, e.g. orifices / nozzles 14, near the lowest point of the cylindrical body 9 at various locations along the length of the auger, to provide an even rate of heat transfer from the water to the product. Also, the upwardly directed flow provides some agitation of the product layer, helping to leach of or wash away sugars from the product surfaces. After passing through the product layer, the water can be discharged laterally, with respect to the transport direction of the product, via an overflow (which can serve as a water discharge port) to discharge compartments at the sides (not shown here). From there, the water can be collected, partially discharged, mixed with fresh make-up water, pressurised, reheated directly by steam or indirectly via a heat exchanger and injected again through the nozzles 14 to the blancher.

[0074] It is also possible that the injected water is transported along with the product towards the product outlet 5 of the blancher, where it is collected in a water discharge pocket 31 (which can also serve as a water discharge port). The water has in that case not necessarily the same longitudinal transport velocity as the product, but usually higher. The water then passes the flights of the auger via perforations 12 in the surfaces of the flights. The higher velocity of the water as compared to that of the product is usually applied for a combination of two reasons: The product is entrained along with the water in forward direction rather than being pushed forwardly by the flights of the auger avoiding product damage by contact with the perforated surfaces. Also, high flow rates of water limit temperature differences inside the blancher, guaranteeing uniform water temperatures throughout the whole process. The blanched product is discharged through the product outlet opening 5 to, for example, a dewatering screw 15, wherein the product is conveyed upwardly by an auger 116 with drive motor 17 to a discharge opening 18 for the blanched product 19. A rotational speed of the auger 116 can be controlled by the drive motor 17 to adapt the discharge capacity of the auger 116 to the product supply rate from the blancher via the discharge opening 5. The product might also be discharged from the blancher by other known means, not shown here, such as for example a Ferris wheel.

[0075] The temperature of the thermal treatment process, i.e. of the water volume inside the blanching compartment, is kept at the desired value of typically 70 to 90°C by injecting hot water of typically 75 to 95°C to the body 9 through the multiple injection nozzles 14. The flow rate per nozzle can be adjusted by valves 21 in the supply line of each nozzle. The to be injected water is suppled by a circulation pump 22 and is brought to the mentioned setpoint temperature of typically 75 to 95°C by a heater 23, which can provide thermal energy to the to be injected water directly, for example from injected steam, or indirectly, via a heat exchanger. The amount of thermal energy supplied to the to be injected water is controlled by a temperature transmitter 24 inside the to be injected water stream at a location downstream of the heater 23 and a control valve 25 for adjustment of the thermal energy supply to the heater 23. An outlet side of the heater 23 can be connected to a manifold 26 which distributes the to be injected water to the respective inlet nozzles 14. The concentration of dissolved substances such as dissolved or leached of sugars is maintained below a maximum value by a supply 27 of fresh (e.g. clean) water to the blancher, for example at the inlet of the pump, and the discharge of water from the blancher body for example via one or more overflow pockets 28 which are connected to one or more drain outlet pipes 29 to one or more water drains 30.

[0076] It is also possible that multiple pumps 22 are installed, some of which take water from the product inlet side of the auger and injecting the water after reheating near the product outlet side of the auger while others take water from the product outlet side of the auger and inject the water after reheating near the product inlet side of the auger. Unlike belt blanchers, screw type blanchers typically operate a more or less constant temperature level throughout the entire length of the auger 2, from product supply to the product discharge, with water temperature differences preferably less than about 5 to 10 degrees to guarantee a correct temperature treatment along the entire process. These differences are maintained within said tolerances by injecting and discharging sufficiently high water flow rates via the circulation pump(s) 22. The same applies for the water quality (i.e. concentrations of from the product into the water dissolved matters) within the conveying screw, which for these high flow rates is more or less equal across the whole length of the auger. As explained above, this aspect of screw blanchers limits their process controllability, the ability of low temperature energy reclaim and the option to discharge and supply water at those parts of the process where most sugars are leached of or dissolved.

[0077] Figure 2 (i.e. Figures 2A, 2B) shows an example of a rotary screw type thermal treatment system 32 (and corresponding method), in this example for the blanching of food products, that obviates, or at least diminishes the disadvantages mentioned above for rotary screw and belt blanchers. More in general, it is an object to provide a compact and cleanable thermal treatment system and method with optimal flexible process controllability, the ability of low temperature energy reclaim, minimization of the use of fresh make-up water and minimal product damage.

[0078] The embodiment according to Figure 2 contains several items with similar names and functions as in the embodiment of Figure 1. These similar items are indicated by the same reference numerals. The following explanation of the working principle of the embodiment according to Figure 2 is substantially limited to the differences with Figure 1 for conciseness.

[0079] In particular, Figure 2 shows a thermal treatment system 32, comprising a treatment chamber 9 having a product inlet 4 for receiving product to be treated and a product outlet 5 for discharging the product. The treatment chamber 9 includes a (single) horizontal rotatable auger 2 to convey the product in a product flow (transport) direction X from the product inlet 4 to the product outlet 5. As follows from the drawing, the product flow direction X is generally in parallel with an axis of rotation of the auger 2.

[0080] As follows from the drawings, the auger’s flight is uninterrupted, viewed along a longitudinal direction of the chamber (i.e. the cylindrical body 9), that is: the respective auger flight preferably extends continuously from the product entrance 4 to the product discharge 5, and preferably does not contain axially spaced-apart (separate) auger sections. It follows that during operation, product can be fed along a substantially uninterrupted, substantially straight direction (e.g. a substantially horizontal direction) from the product entrance 4 to the product discharge 5 of the chamber, the product remaining (substantially submerged) in the treatment liquid (and not being lifted to a vertical level that is above a level of the treatment liquid in the chamber).

[0081] In particular, as will explained below in more detail, the system is preferably configured to provide at least two successive treatment zones (i.e. a first treatment zone 43 and a second treatment zone 44), which can be separated by an imaginary zone interface 45. The uninterrupted auger’s flight can penetrate (i.e. pass, cross, extend through) the imaginary zone interface 45, as follows from the exemplary drawings, to provide submerged product transfer (between the respective zones 43, 44) through the zone interface 45.

[0082] The treatment chamber 9 has at least one liquid supply port 36, 37 (for example a number of first ports 36 and a number of second ports 37) for feeding thermal treatment liquid (e.g. water) into the chamber. A longitudinal position of each of the liquid supply port(s) 36, 37 can be at a relatively close distance from an axial center of the auger 2, but that is not required. Herein, the term longitudinal’ can be defined as being in parallel with the axis of rotation of the auger 2 (i.e. in parallel with a center line of the chamber 9).

[0083] The treatment chamber 9 also has at least one first liquid discharge port 33, 41 for discharging treatment liquid from the chamber 9, each first discharge port being located upstream with respect to the at least one supply port 36, 37, viewed relative to said product flow direction X, for example near the product inlet 4. The liquid discharge port(s) can include e.g. a discharge pocket 33 and / or a first overflow 41 (see above).

[0084] Further, the treatment chamber 9 has at least one second liquid discharge port 31, 28 for discharging treatment liquid from the chamber 9, each second discharge port 31, 28 being located downstream with respect to the at least one supply port 36, 37, viewed relative to said product flow direction, for example near the product outlet 5. The second liquid discharge port(s) can e.g. include one or more water discharge connections / outlets 16 and / or a respective discharge pocket 31 of the chamber 9 and / or an overflow pocket 28.

[0085] It is preferred that the horizontal rotatable auger 2 has perforated flights (as in Fig. 1C, showing the auger perforations 12 in a respective front view), allowing passage of the liquid through the flights during operation.

[0086] For example, each liquid supply port 36, 37 can include or be provided by at least one respective injection nozzle for injecting treatment liquid into the chamber 9. Each nozzle can extend opposite a flight of the auger 2, for example below the auger 2.

[0087] The treatment chamber 9 is preferably configured to be partially filled with thermal treatment liquid for providing entire submersion of product to be treated, wherein the treatment chamber 9 preferably includes a cylindrical body which partially envelops the auger 2, at least for a lower part.

[0088] In particular, the system includes a plurality of spaced-apart liquid supply ports 36, 37 extending along the treatment chamber 9, between the product inlet 4 and product outlet 5, wherein the liquid supply ports 36, 37 are located for example in or near a bottom of the chamber 9, for example at various locations along the length of the chamber 9.

[0089] For example, the system can include a common manifold 26 for supplying liquid to each of the liquid supply ports 36, 37.

[0090] The manifold 26 is preferably divided in separate manifold sections associated with different liquid supply ports 36, 37, in particular such that no direct liquid transport is possible between the sections of the manifold 26. The manifold 26 can include a number of valves 46, 47 for controlling flow to or from different sections of the manifold 26, and / or for dividing the manifold into several sections. For example, the manifold can include a (central) valve 46 dividing the manifold in two separate manifold sections. Also, each of the manifold sections can include one or more respective section valves 47 for dividing those sections further. The present example has three manifold valves 46, 47 (providing four manifold sections), it will be appreciated that more or less manifold valves (and manifold sections) are also feasible.

[0091] According to an embodiment, a first section of the manifold 26 can be coupled to a first liquid discharge port 33 (in particular the discharge pocket 33) for receiving discharged liquid therefrom, wherein a second section of the manifold 26 can be coupled to a second liquid discharge port 31 (in particular a respective discharge pocket 31) for receiving discharged liquid therefrom.

[0092] The system can include heating means 38, 23, for example at least a first heater 38 and a second heater 23, for heating liquid that is fed to at least a first port 36 of the of liquid supply ports (e.g. via said manifold 26) to a first treatment temperature and for heating liquid that is fed to at least a second port 37 of the of liquid supply ports to a second treatment temperature, the second treatment temperature being higher than the first treatment temperature. For example, during operation, the liquid supplied to the first section of the manifold 26 can be heated to a certain first temperature by the first heater 38 and the liquid supplied to the second section of the manifold 26 can be heated to a certain second (different) temperature by the second heater 23.

[0093] Similarly, the system can include including first pumping means 34 (e.g. a pump), connected to a fluid discharge line / connection 35 of a first liquid discharge pocket the chamber 9, for pumping liquid to at least a first port 36 of the of liquid supply ports (at a respective first flow rate). The fluid discharge connection 35 can e.g. provide part of a respective first water discharge port of the system.

[0094] The system can include second pumping means 22, connected to a fluid discharge line / connection 16 of a second liquid discharge pocket 31 of the chamber 9, for pumping liquid from the chamber to at least a second port 37 of the of liquid supply ports (at a respective second flow rate, for example a second flow rate that differs from the first flow rate).

[0095] For example, during operation, treatment liquid can be supplied to the first section of the manifold 26 and is pressurized to a certain first flowrate by the first pump 34, and whereby the liquid can be supplied to the second section of the manifold 26 and is pressurized to a certain second flowrate by the second pump 22.

[0096] Preferably, the system includes at least three liquid supply ports 36, 37, being located at mutually different longitudinal chamber positions. The present example includes at least two first liquid supply ports 36 (at two different longitudinal positions) and two second liquid supply ports 37 (located downstream of the first supply ports 36 and also at two different longitudinal positions). Subsequent (neighboring) liquid supply ports 36, 37 can be spaced-apart longitudinally over various distances (for example in the range of 20-100 cm), depending e.g. on the size of the chamber 9 and a desired range of setting a position of an imaginary zone interface 45 (see below).

[0097] Preferably, flow control means (e.g. valves) 21, 46, 47 are provided for controlling liquid flow to each of the plurality of liquid supply ports 36, 37, for example such that a longitudinal position of liquid supply into the chamber 9 can be selected or adjusted (and such that a longitudinal position of the imaginary zone interface 45 can be adjusted). The valves 46, 47 of the manifold 26 can e.g. provide (at least part of) such flow control means. Also, valves 21 of supply lines between the manifold 26 and downstream liquid supply ports 36, 37 can provide (at least part of) the flow control means.

[0098] For example, the control means 21, 46, 47 can be operated (e.g. set to a first flow control state) for blocking flow to an upstream first liquid supply port 36 while allowing flow to the other first liquid supply port(s) 36 located downstream with respect to the blocked first liquid supply port. Also, the control means 21, 46, 47 can be used for blocking flow to an upstream second liquid supply port 37 while allowing flow to the other second liquid supply port(s) 37 located downstream with respect to the blocked second liquid supply port. In this way, a (horizontal) length of a corresponding first treatment zone 43 in the chamber 9 can be expanded whereas a (horizontal) length of the second treatment zone 44 can be limited (and a virtual zone interface 45 can be shifted correspondingly). Also, in this way, treatment intervals / times concerning the two zones 43,44 can be adjusted.

[0099] Similarly, the control means 21, 46, 47 can be operated (e.g. set to a second flow control state) for allowing flow to an upstream first liquid supply port 36 while blocking flow to the other first liquid supply port(s) 36 located downstream with respect to the former first liquid supply port. Also, the control means 21, 46, 47 can be used for allowing flow to an upstream second liquid supply port 37 while blocking flow to the other second liquid supply port(s) 37 located downstream thereof. Thus, the length of the first treatment zone 43 can be limited whereas the length of the second treatment zone 44 can be expanded (a virtual zone interface 45 shifting correspondingly).

[0100] It will be appreciated that the control means 21, 46, 47 can be adjusted in various (different) ways, depending on the arrangement and number of respective liquid supply ports 36, 37, in particular for setting zone lengths of the treatment zones 43, 44. For example, the control means 21, 46, 47 can be set to a state wherein all first supply ports 36 and all second supply ports 37 simultaneously supply (e.g. inject) liquid into the treatment chamber 9.

[0101] According to an embodiment, the system is configured such that the treatment chamber 9 is divided into a first treatment zone (area) 43 and a (downstream, adjacent) second treatment zone (area) 44, the horizontal auger 2 extending through both zones 43, 44. Each zone is preferably associated with at least one individual liquid supply port 36, 37 as well as a respective individual liquid discharge port 33, 41, 31, 28. During operation treatment liquid is preferably transported in counterflow with a main longitudinal product transport direction in the first zone 43 and in parallel direction with the main product transport direction in the second zone 44.

[0102] Operation of the system can include a thermal treatment method, for example a blanching method, wherein the method includes:

[0103] -feeding treatment liquid e.g. water, fresh (clean) water, potable water into a treatment chamber 9, containing a rotating horizontal auger 2, via at least one liquid supply port 36, 37;

[0104] -feeding product into the treatment chamber 9 via a product inlet 4;

[0105] -transporting the product, in a product flow direction, from the product inlet 4 to a product outlet 5, at least partly by the rotating auger 2;

[0106] -discharging treatment liquid downstream of said at least one liquid supply port 36, 37 via at least one first liquid discharge port 33, 41; and -discharging treatment liquid upstream of at least one liquid supply port 36, 37 via at least one second liquid discharge port 31, 28.

[0107] In particular, treatment liquid can be fed to the afore-mentioned first port at a first treatment temperature, wherein treatment liquid is fed to the afore-mentioned second port at a second treatment temperature, the second treatment temperature for example being higher (or lower) than the first treatment temperature.

[0108] During operation, flow to the plurality of liquid supply ports 36, 37 can be controlled, in particular for selecting or changing a longitudinal position of liquid supply into the chamber 9, for example by opening one or more ports at a first longitudinal position and closing one or more ports at one or more other longitudinal positions.

[0109] For example, treatment liquid can be fed to a first port 36 at a first flow rate, wherein treatment liquid is fed to a second port 37 at a second flow rate, wherein the first flow rate and the second flow rate are independently controlled during operation. It is preferred that a first treatment process of the product, for example a heating process, takes place in a first zone 43 in counterflow with the treatment liquid, whereby a second treatment process of the product takes place in a second zone 44 wherein the treatment liquid flows in the same direction as the product flow direction, the first zone 43 and second zone 44 being traversed by the rotating auger 2.

[0110] Preferably, a liquid flow rate across an imaginary interface 45 between the first zone 43 and second zone 44 can be negligible (i.e. substantially or close to zero) as compared to each of liquid flow rates through the zones 43, 44 (to the respective discharge ports) and / or compared to each of liquid flow rates through the supply ports. For example, during operation, a liquid flow rate (m3 / h) through the imaginary interface 45 can be smaller than 10% of a flow rate of liquid supplied to the first supply port(s) 36, and preferably at most about 5% or 1% of a flow rate of liquid supplied to the first supply port(s) 36.

[0111] For example the method can comprise the submersion of the product in and transport through the treatment liquid (through the subsequent treatment zones 43, 44) in the chamber 9 during a certain predefined treatment time, whereby this treatment time consists of a first interval (corresponding to treatment in the first zone 43) and a second interval (corresponding to treatment in the second zone 44). During the first interval the product is exposed to a first liquid circulation (i.e. liquid flow), for example at a first temperature and a first liquid quality, the first liquid circulation W 1 being in counterflow with a main direction of transport X of the product through the chamber 9. During the subsequent second interval the product is exposed to a second liquid circulation (flow) W2, for example at a second temperature (that can be different from said first temperature) and for example a second liquid quality (that can be different to said first liquid quality), the second liquid circulation (i.e. flow) W2 being parallel to the main direction of transport X of the product through the chamber 9. In particular, as follows from the above and as will be appreciated by the skilled person, said liquid quality is associated with concentrations of from the product into the water dissolved matters, i.e. contamination, the contamination in particular being dissolved product matter (such as for example dissolved or leached of sugars). It follows that the first liquid quality can be associated with liquid having a first amount of contamination (e.g. a first concentration of dissolved product matter), and the second liquid quality can be associated with liquid having a second amount of contamination (e.g. a second concentration of dissolved product matter), wherein the first amount of contamination (significantly) differs from the second amount of contamination.

[0112] The relative duration of the first and second interval as portions of an overall treatment time can preferably be selected or adjusted or more or less freely chosen, in particular by changing the lengths of the zones 43, 44 by changing the longitudinal position of the zone interface 45 (which can be achieved by setting said control means 11 to a suitable flow control state, as has been described above).

[0113] More particularly, the embodiment 32 according to Figure 2 preferably contains:

[0114] - a first water discharge pocket 33 from the cylindrical body 9 near the product inlet 4, wherein the first water discharge pocket 33 can provide at least part of said first (upstream) discharge port;

[0115] - a second water discharge pocket 31 from the cylindrical body 9 near the product discharge opening 5, which second discharge pocket 31 can provide at least part of the second (downstream) discharge port;

[0116] - a first circulation pump 34, for pumping or pressurizing water received from one or more first water discharge connection(s) 35 of the first discharge pocket 33 to a first set of injection nozzles 36 (i.e. first supply ports);

[0117] - a second circulation pump 22, pressurizing water received from one or more second water discharge connections 16 of the second discharge pocket 31 to a second set of injection nozzles 37 (i.e. second supply ports); - a first heating device 38, which is preferably configured for directly or indirectly heating the water from the first injection pump 34 to a first temperature setpoint TT1 39 by means of a control valve TCI 40, a water discharge of the heater 38 being connected to a first end of the common water inlet manifold 26;

[0118] - a second heating device 23, which is preferably configured for directly or indirectly heating the water from the second injection pump 22 to a second temperature setpoint TT2 24, a water discharge of the heater 23 being connected to a second end of the common water inlet manifold 26;

[0119] - one or more first water overflow pockets 41 located near the product inlet 4 of the conveying screw 2;

[0120] - one or more second water overflow pockets 28 located near the product discharge 5 of the conveying screw 2;

[0121] - a first fresh water make-up (i.e. liquid supply) 42, for example to the inlet of the first circulation pump 34;

[0122] - a second fresh water make-up (i.e. liquid supply) 27, for example to the inlet of the second circulation pump 22.

[0123] As follows from the above, two successive zones are distinguished in the body 9, denoted as The first zone 43 and the second zone 44, each preferably with distinct water supply temperature TT1 and TT2 and e.g. distinct concentrations of dissolved matters or leached of sugars into the water during operation. The first zone 43 is located near the product inlet side 4 of the auger 2 and the second zone 44 , near the product discharge 5 of the auger 2. During use, the first zone 43 receives water from the first pump 34 and first heating device 38 via at least oneof the first injection nozzles 36 near the bottom of the cylindrical body 9. The second zone 44 receives water from the second pump 22 and second heating device 23 via at least one of the second injection nozzles 37 at the bottom of the cylindrical body. The location of said vertical imaginary interface 45 between the first zone 43 and the second zone 44 is preferably located at some point between the inlet side and outlet side of the screw conveyer 2, and is adjustable as is mentioned above. The exemplary drawing shows the position of the imaginary zone interface 45 at an imaginary vertical intersection located at the point where an optional valve 46 in the common water inlet manifold 26 is closed, the other valves 47 in the common water inlet manifold e.g. being open; naturally, different positions are feasible depending on the manifold arrangement, control means 11 settings and the-like.

[0124] According to an embodiment, the first zone 43 can mainly serve for heating up the product, from a relatively low product inlet temperature to a first, higher temperature controlled e.g. by setpoint TT1 of control valve 40. The longitudinal component of the water flow direction is in the first zone 43 opposite to that of the product transport direction, which enhances heat transfer from the relatively warm water to the colder incoming product, which is beneficial especially in the first zone 43 where the energy demand for heating up the initially relatively cold product is relatively high. The counterflow in the first zone 43 is also beneficial e.g. to efficiently leach of or dissolve sugars from the fresh incoming product surfaces. The second zone 44 can mainly serve for retaining the product at a more or less constant high, second temperature, determined by setpoint TT2 which is controlled by control valve 25, for example for blanching the product and particularly in case of potatoes to gelatinize the starch in the potatoes, at a temperature of for example 70 to 90°C.

[0125] The product heating rate in the first zone 43 can generally depend on various the product characteristics, such as thickness, thermal conductivity and specific heat capacity. Also, some products might require a specific temperature evolution, as described earlier.

[0126] According to an embodiment, the length of the first zone 43 and the second zone 44 can be adapted to the specific characteristics or demands of the product, by selecting which of the valves 46, 47 in manifold 26 are to be closed, the others being open, and / or by adjusting the flow line control valves 21 (as is mentioned above). Herewith, the position of the interface 45 is translated along the length of the screw conveyor 2. According to a preferred embodiment, the temperatures of the respective the first zone 43 and the second zone 44 can subsequently freely be adapted by the independent temperature controls 40, 25 per zone. The energy demand of the first zone 43 is generally relatively high as compared to that of the second zone 44, but typically requires a lower heat supply temperature TT1 in the case where the energy is supplied indirectly to the recirculating water, via a heat exchanger. The energy demand of the second zone 44, with more or less constant product temperature, is generally lower than that of the first zone 43, but usually requires heat supply at a somewhat higher temperature TT2 in case of indirect heating of the recirculating water. The longitudinal component of the water flow direction is in the second zone 44 parallel to that of the product, though usually of larger magnitude than that of the product. This is beneficial for entrainment of the product away from the perforated surfaces of the flights of the auger 2, minimizing propulsive forces from the auger to the product and therefore minimizing damage.

[0127] According to an embodiment, and depending on the type of product that is processed, the rate at which soluble matters are released by the product to the water, such as leaching of or dissolving of sugars, will probably be the highest at the start of the blanching process, i.e. in the first zone 43. The supply of fresh water to this zone via fresh water supply 42 and the associated overflow of water from this zone 43 via the respective discharge pocket(s) 41 can preferably be chosen independently from that of the second zone 44, also because the flow rate of water across the vertical imaginary interface 45 between the first zone 43 and the second zone 44 can be negligible or zero, by balancing the volume flow rate of water supply and discharge to and from respectively the first zone 43 and the second zone 44.

[0128] It has been found that in this way a compact and cleanable rotary screw type thermal treatment or blanching system is provided, with two successive zones each 43, 44, preferably with a different water supply temperature and e.g. a different water quality, which can be chosen independently and therefore provides optimal process controllability, the ability of low temperature energy reclaim, minimization of the use of fresh make-up water and minimal product damage.

[0129] Figure 3 shows an example of a typical temperature evolution of a blanching process in an embodiment 1 according to the present state of the art, for example as shown Figure 1. In this example, 10,000 kg / h of potato slices with 10 mm thickness are supplied to the blancher at a temperature of 20°C and are blanched for a duration of 25 minutes in the embodiment 1 of Figure 1. Flowrate of pump 22 is in this example 115 m3 / h, injected equally through 4 nozzles 14 at a temperature of 78°C. The product reaches a temperature of 74°C after 25 min blanching, which requires about 527 kW thermal energy for heating the product by the recirculation water, in this example excluding thermal losses of the blancher, energy to heat up fresh make-up water and pump energy. The return temperature of the recirculating water from the blancher to the heater 23 is about 74°C. If energy for the blanching process is supplied indirectly via heat exchanger 23, then the temperature level of the heating medium should be at least as high as 83°C, with about 79°C outlet temperature from the heater, assuming 5 degrees temperature difference between the hot medium and cold medium through heat exchanger 23.

[0130] Figure 4 shows an example of a typical temperature evolution of a heat treatment process according to an embodiment of the present invention, in this example a blanching process in the embodiment 32 from Figure 2, with two successive zones 43, 44. The flowrate of pump 34 of the first zone 43 is 35 m3 / h and that of pump 22 in the second zone 44 is also 35 m3 / h. The water to the first zone 43 is injected through nozzles 36 at a temperature TT1 of 70°C. The water to the second zone 44 is injected through nozzles 37 at a temperature TT2 of 75°C. According to Figure 4 the product is heated in the first zone 43 to 69°C, which requires 478 kW thermal energy (again excluding thermal losses, heating of make-up water and pump energy) for the first zone 43, with about 58°C return temperature of the water via water outlet 35 and pump 34 to heat exchanger 38. The average product temperature at the end of the second zone 44 is 74°C, hence the same as for the embodiment 1 and Figure 3. This requires 49 kW thermal energy for the second zone 44. The total energy demand of the first zone 43 and the second zone 44 is hence the same as that for the example of Figure 3, 527 kW, but the second zone 44 requires herein a negligible amount as compared to the first zone 43.

[0131] The energy demand of the blanching process according to an example of the present invention is hence mainly determined by that of the first zone 43. If the energy for the first zone 43 is supplied indirectly via heat exchanger 38, with setpoint TT1 of 70°C, then the temperature level of the heating medium should be at least as high as 75°C, with 63°C outlet temperature from the heater 38, again assuming 5 degrees temperature difference between the hot medium and cold medium through heat exchanger 38. The temperature level of the majority of the heating process is hence reduced by at least 8 degrees as compared to a similar thermal process according the present state of the art, which is beneficial for energy recuperation. The water circulation flow rate has also reduced, from 115 m3 / h for the present state of the art to 2 x 35 = 70 m3 / h for the new embodiment, which saves pump energy and reduces costs for the water supply and discharge equipment. Moreover, the water supply flow rate to the first zone 43 and the second zone 44 can be chosen independently and can therefore be adjusted to the rate of dissolution of matters from the product to the water, minimizing the total water consumption and discharge of the blanching process.

[0132] Herein, the invention is described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein, without departing from the scope of the invention as is defined in the claims.

[0133] The two pumps 34 and 22 may for example be combined to a single pump, and heat exchangers 38 and 23 to a single heat exchanger, still preserving the majority of the advantages of the present invention over the present state of the art. The amount of injection nozzles 36, 37 that inject water to respectively the first zone 43 and the second zone 44 might also be different than shown in Figure 2, without departing from the essential characteristics from the present invention. It is also possible that the closed valve 46 in the manifold 26 is replaced by a closed pipe piece and that the open valves 47 are replaced by an open pipe pieces, whereby each of the pipe pieces can be mounted at any location in the manifold 26, in order to adapt relative potion of nozzles 36 belonging to the first zone 43 and nozzles 37 belonging to the second zone 44. For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, alternative embodiments having combinations of all or some of the features described in these separate embodiments are also envisaged.

[0134] However, other modifications, variations, and alternatives are also possible. The specifications, drawings and examples are, accordingly, to be regarded in an illustrative sense rather than in a restrictive sense.

[0135] For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

[0136] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘at least one’, and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to an advantage.

[0137] Also, as follows from the above, a relative lengths of the screw conveyor attributed to the first counterflow zone and second in-line flow zone can preferably be adjusted, for example by opening or closing valves in a respective water supply manifold. Besides, it is preferred that an aforementioned first zone is separated from the respective second zone through a vertical imaginary interface, wherein e.g. water flow across this vertical interface, i.e. from the first zone to the second zone or vice versa is negligible as compared to the water transport flow rates through the respective zones.

[0138] Further, it will be clear that the system can include a process controller (known per se) for controlling operation of various system components (such as setting / adjusting valves to certain valve states, setting / adjusting heaters to certain liquid heating states, setting / adjusting pumping means to certain liquid pumping states, setting / adjusting motor speeds, and the-like). Control of system components by e.g. a central process controller and using e.g. suitable communication lines and / or control signals (and e.g. process monitoring sensor signals), is known per se.

Claims

Claims1. A thermal treatment system, comprising a treatment chamber (9) having a product inlet (4) for receiving product to be treated and a product outlet (5) for discharging the product, wherein the treatment chamber (9) includes a horizontal rotatable auger (2) to convey the product in a product flow direction (X) from the product inlet (4) to the product outlet (5), wherein the treatment chamber (9) has at least one liquid supply port (36, 37) for feeding thermal treatment liquid into the chamber, wherein the treatment chamber (9) has at least one first liquid discharge port (33, 41) for discharging treatment liquid from the chamber (9), the first discharge port being located upstream with respect to the at least one supply port (36, 37), viewed relative to said product flow direction (X), for example near the product inlet (4), wherein the treatment chamber (9) has at least one second liquid discharge port (31, 28) for discharging treatment liquid from the chamber, the second discharge port (31, 28) being located downstream with respect to the at least one supply port (36, 37), viewed relative to said product flow direction (X), for example near the product outlet (5), wherein the auger (2) is preferably uninterrupted, viewed along a longitudinal direction of the chamber (9), wherein the system is preferably configured such that the product can remain entirely submergedin treatment liquid during transport through the chamber (9) from the product inlet (4) to the product outlet (5).

2. A thermal treatment system according to claim 1, wherein each liquid supply port (36, 37) includes at least one injection nozzle for injecting treatment liquid into the chamber (9), the nozzle extending opposite a flight of the auger (2), for example below the auger (2).

3. A thermal treatment system according to claim 1 or 2, wherein the horizontal rotatable auger (2) has a perforated flight.4 A thermal treatment system according to any of the preceding claims, wherein the treatment chamber (9) is configured to be partially filled with thermal treatment liquid for providing entire submersion of product to be treated, wherein the treatment chamber (9) preferably includes a cylindrical body which partially envelops the auger (2), at least for a lower part.

5. A thermal treatment system according to any of the preceding claims, including a plurality of spaced-apart liquid supply ports (36, 37) extending along the treatment chamber (9), between the product inlet (4) and product outlet (5), wherein the liquid supply ports (36, 37) are located for example in or near a bottom of the chamber (9), for example at various locations along the length of the chamber (9).

6. A thermal treatment system according to claim 5, including a common manifold (26) for supplying liquid to each of the liquid supply ports (36, 37), wherein the manifold (26) is preferably divided in separate manifold sections associated with different liquid supply ports (36, 37), in particular such that no direct liquid transport is possible between the sections of the manifold (26).

7. A thermal treatment system according to claim 6, wherein a first section of the manifold (26) is coupled to the first liquid discharge port (33) for receiving discharged liquid therefrom, wherein a second section of the manifold (26) is coupled to the second liquid discharge port (31) for receiving discharged liquid therefrom.

8. A thermal treatment system according to any of the claims 5-7, including heating means (38, 23), for example at least a first heater (38) and a second heater (23), for heating liquid that is fed to at least a first port (36) of the of liquid supply ports to a first treatment temperature and for heating liquid that is fed to at least a second port (37) of the of liquid supply ports to a second treatment temperature, the second treatment temperature being higher than the first treatment temperature.

9. A thermal treatment system according to any of claims 5-8, including pumping means (34, 22), for pumping liquid to at least a first port (36) of the of liquid supply ports at a first flow rate and for pumping liquid to at least a second port (37) of the of liquid supply ports at a second flow rate, for example a second flow rate that differs from the first flow rate.

10. A thermal treatment system according any of claims 5-9, including flow control means (21, 46, 47) for controlling flow to each of the plurality of liquid supply ports (36, 37), for example such that a longitudinal position of liquid supply into the chamber (9) can be selected or adjusted.

11. A thermal treatment system according any of the preceding claims, wherein the system is configured such that the treatment chamber (9) is divided into a first treatment zone (43) and second treatment zone (44), the horizontal auger (2) extending through both zones, in particular such that the auger (2) can pass product between the first treatment zone (43) and second treatment zone (44) in a submerged manner, each treatment zone being associated with at least one individual liquid supply port (36,37) as well as a respective individual liquid discharge port (33, 41), whereby during operation treatment liquid is preferably transported in counterflow with a main longitudinal product transport direction in the first zone (43) and in parallel direction with the main product transport direction in the second zone (44).

12. The system according to claim 11, wherein a location of a vertical imaginary interface (45) between the first treatment zone (43) and the second treatment zone (44) is located at a point between an inlet side and an outlet side of the auger (2), wherein a flight of the auger (2) penetrates the imaginary interface between the first treatment zone (43) and the second treatment zone (44).

13. A thermal treatment method, for example a blanching method, utilizing the system according to any of the preceding claims, wherein the method includes:-feeding treatment liquid into the treatment chamber (9), containing the rotating horizontal auger (2), via the at least one liquid supply port (36, 37);-feeding product into the treatment chamber (9) via the product inlet (4); -transporting the product, in a product flow direction, from the product inlet (4) to the product outlet (5), at least partly by the rotating auger (2);-discharging treatment liquid upstream of said at least one liquid supply port (36, 37) via the at least one first liquid discharge port (33, 41); and discharging treatment liquid downstream of at least one liquid supply port (36, 37) via the at least one second liquid discharge port (31, 28).

14. The thermal treatment method according to claim 13 in combination with at least claim 5, wherein treatment liquid is fed to a first port (36) of the at least one liquid supply port at a first treatment temperature, wherein treatment liquid is fed to a second port (37) of the at least one liquid supply port at a second treatment temperature, the second treatment temperature being different from, e.g. higher or lower than, the first treatment temperature.

15. The thermal treatment method according to claim 13 or 14 in combination with at least claim 5, including controlling flow to the plurality of liquid supply ports (36, 37), in particular for selecting or changing a longitudinal position of liquid supply into the chamber (9), for example by opening one or more ports at a first longitudinal position and closing one or more ports at one or more other longitudinal positions.

16. The thermal treatment method according to any of claims 13-15 in combination with at least claim 5, wherein treatment liquid is fed to a first port (36) of the at least one liquid supply port at a first flow rate, wherein treatment liquid is fed to a second port of the at least one liquid supply port at a second flow rate, wherein the first flow rate and the second flow rate are independently controlled.

17. The thermal treatment method according to any of claims 13-16, whereby a first treatment process of the product, for example a heating process, takes place in a first zone (43) in counterflow with the treatmentliquid, whereby a second treatment process of the product takes place in a second zone (44) wherein the treatment liquid flows in the same direction as the product flow direction, the first zone (43) and second zone (44) being traversed by the rotating auger (2).

18. The thermal treatment method according to claim 17, whereby a liquid flow rate across an imaginary interface (45) between the first zone (43) and second zone (44) is negligible as compared to each of liquid flow rates through the zones (43, 44) and / or compared to each of liquid flow rates through the supply ports (36, 37).

19. The thermal treatment method according to any of claims 13-18, wherein water, for example fresh water, is supplied to the at least one supply port (36, 37) as treatment liquid.

20. The thermal treatment method according to any of claims 13-19, comprising the submersion of the product in and transport through the treatment liquid in the chamber (9) during a certain predefined treatment time, whereby this treatment time consists of a first interval and a second interval, whereby during the first interval the product is exposed to a first liquid circulation (W 1), at a first temperature and a first liquid quality, in counterflow with a main direction of transport of the product through the chamber (9), and whereby during the second interval the product is exposed to a second liquid circulation (W2), at a second temperature and a second liquid quality, parallel to the main direction of transport of the product through the chamber, whereby the relative duration of the first and second interval as portions of an overall treatment time can preferably be selected or adjusted or more or less freely chosen, wherein in particular said first and second liquid quality is associated with concentrations of from the product into the treatment liquid dissolved matters.

21. The method according to any of claims 13-20, wherein the product remains entirely submerged in the treatment liquid during its transport from the product inlet (4) to the product outlet (5).

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