JPH02504331A - Apparatus for heating conductive flowable media and method of using such apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Apparatus for heating conductive flowable media and method of using such apparatus The present invention provides an apparatus for heating an electrically conductive flowable medium and a method for using such an apparatus. It relates to the method used.

There are many situations where it is necessary to heat a flowable medium to an elevated temperature, e.g. , heating and chemical reactions of food for cooking or sterilization. This is the heating of chemical reactants.

heating a flowable medium by passing an electric current directly in the medium between electrodes is known. The advantage of such direct electrical resistance heating of the medium is that it The heating rate is obtained and, to a first approximation, the heating is at a uniform rate throughout the material. Is Rukoto. This is done by heating the medium by transferring heat from the hot surface. between the medium that forms and is in more direct contact with the surface and the rest of the medium. Heat exchangers, ovens and steam or hot water jackets where temperature gradients are unavoidable between In contrast to container-like heating systems. In obtaining the perfect heating rate , such heating systems can result in overheating of the medium in most contact with the heating surface. There is sex.

However, even in the resistance heating method, it is possible to flow into the heating device, especially onto the heating electrode. The resistance of some flowable materials, especially foodstuffs, as deposits from functional materials accumulate. There is a problem with heating.

GB 2067390B describes a resistance heating device in which: The electrodes are spaced along the length of the pipe to conduct electricity through the flowable medium to be heated. Place the electrode, which is typically cylindrical, and extend laterally through the enlarged section of the pipe. pass through. This means that the electric field strength at the exposed surface of each electrode is the pipe itself to minimize potential field strength discontinuities associated with Substantially all the current flows from the smooth exposed surfaces of the electrodes spaced apart from each other. It is intended to be made to look like this. The surface of the electrode to remove dirt Pies are also suggested for scraping off. The electrode area is small and between the electrodes Since the distance between the two is large, a high voltage is used. Therefore, the high current at the electrode surface Density is used.

The problem of deposits of flowable media on the pipe walls rather than on the electrodes is no longer I won't say it.

The means for reciprocating the electrodes to scrape them off will not be described in detail. , the construction of such devices requires flexible leads that can carry the very high currents required. lines or keep sliding contacts free from contamination and oxidation It is likely to be complex because it is difficult to do so.

Such a system of electrode movement for scraping has a spacing of 1 (more than 1) in its longitudinal direction. Rather, it is a type of resistance heating device in which the electrodes face each other across the flow direction of the fluid. The former type of system cannot be applied to Operating such devices at relatively low voltages and high currents due to advantageous in that one has the option to For reasons of simplicity, it is best to use voltages on the order of a few hundred ports rather than a few thousand ports. It's quite convenient.

The invention therefore provides an apparatus for resistive heating of electrically conductive flowable media, the The apparatus includes pipe means through which such a medium may be arranged to flow. , the pipe means being adapted to provide resistive heating of the flowable medium therein during use. made of or internally aligned with a material that has sufficiently low conductivity to spaced within the pipe means and used with the medium flowing through it. at least two electrodes arranged in electrical contact when used; , and if any, placed there from the flowable material when the flowable medium is heated flowable medium to remove or deflect material that tends to A flowable medium within one or more zones within the pipe means in which heating of the body occurs during use. transfer within the pipe means for use as an electrode on the internal wall surface of the pipe means in contact with the and movable means.

A movable removal means is installed for scraping the contact with the interior of the pipe means. Preferably, the scraper comprises one or more scraping members.

Such a scraper extends from an upstream end of said pipe means and extends from an upstream end of said pipe means. comprising a portion connected to means for producing scraping movement of said scraper within the Ru.

The scraper comprises a plurality of scraping members spaced longitudinally of the pipe means. Such a scraping member may, for example, be in contact with a reciprocatable carrier member. a section extending from the upstream end of the pipe means and extending from the said scraper. It is connected to means for producing reciprocating movement of the member.

For example, the carrier member extends along the pipe means and against an interior wall of the pipe means. , or a rod or equivalent holding a protruding scraping member extending towards it. It may be a means.

- However, the carrier member may be a rod or a rod on which the scraping member is held. or equivalent means, preferably parallel and elongated carrier means; Preferably, at least some of the scraping members are coupled to a pair of longitudinal carrier means. It is preferable to crosslink between the two.

The other scraping member is moved from one longitudinal carrier means to the other longitudinal carrier means. may extend towards, but not necessarily reach, the means of protection, especially in that case As shown, a shield member exists between the opposing electrodes.

If the internal cross-section of the pipe means is rectangular, the set of scraping members may along the length of the carrier member to successively scrape different opposite pairs of walls. It may be arranged along.

However, other shapes of scrapers may be employed; for example, if the pipe hand If the internal cross-section of the step is generally circular, the scraper will provide the necessary scraping action. It may take the form of an auger helix rotatable within the pipe means to produce the .

Such auger helix is connected to a drive member extending from the upstream end of the pipe means. and may be connected to means for producing rotational movement.

Instead, the scraper may include a plurality of brush members, radially extending blades or is adapted to rotate within the pipe means so as to produce the necessary scraping motion. another radially extending member mounted on and extending from the carrier member; The carrier member may be provided for connection with means for producing the necessary movement. It may extend once again from the upstream end of the pipe means.

The scraping means associated with the above counteract the tendency of the flowable medium to locate on the scraper. within the medium to assist in preventing the adhesion of material inside the pipe means, so as to may be designed to create a high degree of turbulence in the flowable medium, and they may be designed to create a high degree of turbulence in made of or made of materials that do not adhere or adhere only to a reduced degree. Suitable materials for the surface of such scrapers, which may be coated with For example, silicone rubber or polytetrafluoroethylene.

The scraping member is used to avoid shorting the electrodes and to avoid changing the effective electrode area. , preferably made from an insulating material.

The interior of the pipe means has a polygonal cross-section, for example a rectangular cross-section, and the scraping member and where the electrodes are uniform over the area of any pair of electrodes. provide a plurality of flat surfaces that may be installed to provide a fixed interelectrode distance; is preferable.

Instead of a scraping member contacting the pipe means for removing material therefrom close to the electrode and internal pipe means to create turbulence in the flowable medium; However, generally similar members installed so as to pass through without contacting them are adopted. may be used.

The electrodes form one or more pairs of electrodes, the members of each pair of electrodes having a width of the pipe means. preferably across from each other.

Preferably there are at least three pairs of electrodes.

Connect each of the above three electrode pairs between one phase of the three-phase AC voltage power supply and ground. A means for doing so may be provided.

However, other configurations of connections between electrodes and power sources may be used.

For example, a neutral electrode at the end of the pipe means may be connected between the phases.

However, the edge current density on the electrode is an important factor in the lifetime of the electrode. It can be seen that during use this may limit the maximum flow passed through the electrode, e.g. , in a multistage system in which three pairs of electrodes are arranged successively along the pipe means, Each electrode is connected not only to the opposite electrode in its pair, but also to the next and and/or look at the previous electrode. Adjacent electrodes determine how the electrodes are powered. Depending on the be. If there is a phase difference between successive electrodes, it can contribute substantially to the edge current density. A relatively large potential difference develops between adjacent electrodes. Therefore, one example of pipe means Preferably all electrodes are fed in phase, with the amplitude of the feed to each individual electrode being separate. is preferably controlled such that the gap between the electrode pairs is minimized. Ru.

The device operates with a voltage between the electrode pairs of less than 650 volts, preferably approximately 240 volts. preferably moved.

Preferably, said voltage is a low frequency A(l pressure), preferably approximately 50 cycles. Yes.

The device is 1eI! 0.25dmps to 1.2dmps, more preferred 0.4 dmps to 0.5 dmps per d, for example 0.5 dmps per ci It is preferred to conveniently operate at a current density of dmpS.

The advantage of using relatively low voltages is that electrolytic production of oxygen is less likely to occur. And that is 0 of the oxygen in the food! The oxidation of sulfur in the material being heated probably This tends to impair flavor due to the formation of sulfur dioxide.

Optionally, the length of the electrodes, measured in the direction of contraction of the pipe means, is the length between successive pairs of electrodes. The electrical conductivity of the flowable medium decreases in the direction of flow, thereby increasing the temperature. Despite the rate increase, given equal voltage across each of the above electrode pairs, A relatively uniform current distribution is obtained during use.

When the flowable medium is milk, the percentage length reduction between successive pairs is from 5 to 15%; The optimum change in electrode length, preferably approximately 10%, is the flowable medium. As an example, for milk, 80 The preferred length for heating from °C to 140 °C is 89.80 and 71 cm .

Preferably, each electrode is elongated in the sewing direction of the pipe means.

Each electrode is substantially identical to the interior surface area of the pipe means adjacent to the respective electrode. Preferably, it is embedded in the surface so as to form one plane.

The internal surface of the pipe means is formed by a lining of insulating plastic material. is preferable.

Preferably, the poles are embedded within said plastic material.

The above plastic material is elastically pulled before placing each electrode there. Stretch it out and then attach the electrode so as to form a good seal on its edge. It is preferable to snap it loose, and when assembling the device it should be It is preferable to carry out the stretching described above.

The above means for removing material from the interior of the pipe means does not produce resistive heating during use. so as to remove material from the interior of the pipe means over substantially the entire length of the pipe means. Preferably.

The electrode generally has a surface area exposed for current flow; the surface area is an internal surface area of that portion of said pipe means in which resistive heating occurs during use; Preferably, it is greater than 10% of the area.

Preferably, said total surface area is greater than 30% of said internal surface area.

Preferably, the total surface area is approximately 40% of the internal surface area.

As described above,! The current density at the edge of the pole is the maximum that can be passed through and This may therefore be the limiting factor determining the maximum rate of heating that can be obtained.

However, depending on the shape and location of the electrodes, the maximum current density may extend beyond the edge points. It may be.

Preferably, in the device according to the invention one or more shielding members are included, Each of the above-mentioned shield members is thin with respect to the length of the current path within the device, and the shield portion Current density at one or more parts of the electrode surface to find the highest ifL density in the absence of preferably positioned with respect to each electrode or pair of electrodes so as to reduce and the shield member thereby increases the current carrying capacity of the one or more electrodes. do the work.

The electrodes in the device according to the invention can be of virtually any variety, including plate-shaped, cylindrical or spherical. Typically, the area on the electrode where the maximum current density is found depends on the shape of the electrode, the time depends on the nature of the counter electrode, where the electrode defines the current path. The maximum current density is Occurs when the electrode and counter electrode are brought closest to each other, in which case the current path is the closest short, it means that the flowable medium outside the direct path between the electrode and its counterelectrode is When it becomes a current path, it often occurs at the @green electrode. Generally, the shield member is The electrode surface positioned between an electrode and its counterelectrode and otherwise subject to maximum current density Lying on that area of the.

By limiting the current density in these areas with respect to the remaining electrode surface , paradoxically, the t-flow carrying capacity of the device can be increased. The maximum current density is within the permissible range. The average current density can be increased without exceeding the range.

The shielding member is positioned facing the shielded area of the electrode and spaced apart therefrom. It is preferable to extend it by placing it.

The shielding member extends substantially beyond the area of the electrode to be shielded. preferable.

A shielding member overlaps said edge area of the electrode area exposed for current flow. i.e. beyond the edge area outside the electrode area and towards the center of the electrode. Preferably, it extends over a distance.

The distance between the shield member and the distance between the electrode and the counter electrode is 10% to 300%. , preferably overlapping the edge area of the electrode area exposed for current flow.

The shape is from 10% to 100% of the spacing, more preferably from 20% to 100% of the spacing. More preferably up to 50%, for example around 30%.

The shielding member is spaced apart by a distance at least equal to the spacing between the electrodes and their opposing electrodes. preferably by a distance at least twice the said spacing, e.g. at least at least the said spacing. also outward by four times the distance beyond the exposed electrode area for the flow of the IIT current. Preferably, it extends.

The electrodes may be of any shape and have any number of edges or any shape. You may also give an edge.

During use, the shield member rests against the edge of the electrode bounded by the flowable medium. It is preferable that it be provided as follows.

Typically, the or each shield member is substantially between the respective electrode and the counter electrode. Preferably, it is positioned in the upper middle position.

However, the or each of the above-mentioned shield members is may be positioned proximate to each electrode, and optionally associated with the electrode. or for each said shield member, a corresponding shield part for the counter electrode. material may be provided.

Preferably, the or each shield member is a substantially planar member.

-A-wise, the thickness of the shield member in the direction between the electrodes is not H2 field, but it The shielding member, which may be minimized so as not to impede the flow of material through the may have to withstand virtually all voltages applied to the battery, and In addition, it must have sufficient mN strength to withstand the voltage.

The maximum current density at the edge of each electrode should be at least twice the average current density when the device is in use. Below, in some cases it is limited to 1.5 times or less of the average, and in some cases it is limited to 0.65 times. It's okay.

A neutral ring or is the leakage current to the neutral position before the collector electrode is heated and the current reaches the external device. make a branch to This net flow to the neutral device can be virtually eliminated within the device. , where the paired electrodes at the ends of the pipe means of the device are symmetrically opposed A.

C1! When driven by pressure, the electrodes are arranged in opposing pairs along the pipe means. and the shield member overlaps the outside of the counter electrode and the neutral collector electrode or is set by stopping at a certain distance before reaching the ring. The current then around the outer end of the shield member, and rather than the neutral collector. Pass back to the counter electrode. Of the current that reaches the neutral collector electrode, most Everything returns to the opposite pole.

Suitable power sources include, for example, a six-valve rectifier system, a center-neutral single-phase converter, or It may be an inverter that is powered by six sets of power sources.

The advantage of such a construction is that the end capacitance within the pipe means (capacity upstream and downstream of the electrode) amount) can be minimized. Large downstream end capacity only wastes capacity Unfortunately, the minimum hold time can be increased at high temperatures. See you again A smaller, less strictly specified neutral connection may also be employed.

A device is further connected to the downstream end of said pipe means to provide said flowable material by heat exchange. A heat exchanger may be included for cooling the active medium with a flow of coolant.

The apparatus further comprises: downstream of an outflow path for said flowable medium through said heat exchanger; The use of pressure relief valves, which may include pressure relief valves (safety valves) in The superatmospheric pressure maintained in the thermal device is released without boiling, resulting in heating and recooling. The rejected media can be processed at approximately atmospheric pressure during subsequent processing such as backing. You will be able to do it.

The heating produced by a resistive heating device is greater than the heating produced by other forms of heating device. , is found to be much more uniform in nature, but deviations from uniform heating occur. ing. The temperature reached by the material in the heater is a function of the length of time the material is exposed to the electrical current. , depends on the current density.

Liquids and slurries do not move through the pipe at a uniform speed; The degree distribution depends on the flow properties of the material being heated. Some ingredients, especially foods, have very little Heating may be harmful. The effect of non-uniform flow is This is of practical importance when temperature sensitive materials are being heated.

One effect of the above scraper is to create turbulence in the flowable material, thereby creating a uniform Flow rates and even heating have been found to be conducive. Avoid uneven heating The tendency of material to adhere to pipe wall soil due to scraping is often It may be reduced so much that it is not necessary. It also improves the flavor and nutritional value of foods. It no longer hurts. Therefore, without scraping the walls of the electrode and pipe means, It may be of value to produce a high degree of agitation of the flowable medium within the pipe means. Understood.

Accordingly, in a second principal aspect, the invention provides resistive heating of electrically conductive flowable media. provide an apparatus for such a medium to flow therethrough; comprising a pipe means which can be arranged, the pipe means being capable of resisting the flowable medium during use; Made from materials with sufficiently low IT properties so that anti-heating is provided therein, or or internally in line with it and further spaced within and through the pipe means. at least two electrodes arranged in use to be in electrical contact with the medium flowing therethrough; , providing a substantially uniform pipe passage time for all flowable materials. and means for creating agitation or turbulence of the flowable material so as to cause the flowable material to flow.

In such a case (the soldering means may be a fixed flow current transformer, but it may be a moving one ( More preferably it is a strip member, for example a scraping member as described above.

Such agitation means generally move the material from the wall of the pipe means to the center of the pipe means. should be designed to distract and mix well.

As mentioned above, temperature control is quite important when heating food.

The device according to the invention therefore serves as a means for measuring the flow rate of said flowable material. , means for measuring the temperature of said flowable material entering said pipe means; and said control means responsive to the flow rate and temperature measurements and for regulating the passage of the heating current; Measurement of the outlet temperature at which said flowable material is heated within said pipe means Preferably, the control means is further responsive to the outlet temperature and controls the current flow. provides for the passage of

The heating energy provided by the inlet temperature and flow rate is first adjusted, and then the The outlet temperature in the feedback loop can be used to further define the performance. This allows temperature to be more tightly controlled, both in terms of uniformity and absolute levels. I found out. In resistance heaters, the temperature control requirement is Much more important than conventional heaters controlled by heat exchange.

Preferably, said control means are microprocessor control means.

The present invention provides for the passage of a flowable medium through the pipe means of the inventive apparatus as described above. passing the flowable medium between the electrodes to heat the flowable medium; passing an electric current through the flowable medium.

The heating device described above is suitable for packaging machines that can receive the fluid medium directly from the device. A heat exchanger connected directly to the machine or provided to cool the flowable medium. receiving the cooled flowable medium through the exchanger and packaging the flowable medium in the desired manner; It may be coupled to a packaging machine that can.

A device for preheating the flowable medium is installed upstream of the resistance heating device according to the invention. If the flowable medium that may be mixed is a food that requires cooking, the food is For further heating, for example for sterilization, a resistance heating device according to the invention is used. May be partially cooked before being introduced.

The invention will be further explained by the following invention of preferred embodiments with reference to the accompanying drawings. explained and illustrated.

FIG. 1 is a schematic diagram of a device according to the invention installed as part of a food sterilization device; It is.

2 is a front sectional view of the resistance heating device of FIG. 1. FIG.

3 is a front sectional view of the pipe means of the apparatus of FIG. 2; FIG.

FIG. 4 is a sectional view taken along line rV-mV in FIG. 3.

FIG. 5 is a sectional view taken along line 2--2 in FIG.

FIG. 6 is a corresponding portion on the line Vl--Vl of FIG.

7 is a cross-sectional view of the heat exchanger of the apparatus of FIG. 1; FIG.

FIG. 8 is a schematic side view of a second embodiment of a heating device according to the invention.

Figure 9 shows the central element of the apparatus of Figure 8 without details of the electrical connections to the electrodes. Simple 1 through! It is a cross section.

FIG. 10 is a cross-sectional view taken along line xx-xx in FIG. 9.

FIG. 11 shows the example shown in FIGS. 8 and 9 showing electrical connections for - electrodes. FIG. 3 is a plan view of the element.

FIG. 12 is a longitudinal sectional view taken along the line ■-■ in FIG. 11.

FIG. 13 is a longitudinal section through the inlet end region of the device of FIGS. 8 to 12; Ru.

FIG. 14 is a longitudinal section through the outlet end region of the device of FIGS. 8 to 13; Ru.

FIG. 15 is a computer simulation of the equal distribution of the devices shown in FIGS. 8 to 14. It is a tion.

Figure 16 shows Figures 8-8 in use with the center electrode pair switched off. 14 is a computer simulation of the equal distribution of the device of FIG. 14.

As shown in Figure 1, the device for sterilizing spillable food is a first food holding tank having an inlet 2 for the pressurized atmosphere and an inlet 3 for the pressurized atmosphere; 1, this device may be equipped with a similar inlet 5 for food and a pre-pressure gas inlet 5. A separate food holding tank 4 may be provided, having an inlet 6.

The food holding tanks 1 and 4 are connected via a switching valve 7, which will be described in more detail below. It may be connected to the inlet of the resistance heating device 8 of the present invention.

The heating device has pipe means and an inlet lO for flowable food and sterilization. A tube 9 is provided with an outlet end 11 for the food to be consumed.

The outlet end 11 of the heating device Wt8 is provided with a liquid coolant, which will be explained in more detail below. is connected to an inlet 13 for the flow of water and a heating coil 15 in the food holding tank 4. , and an outlet 14 for the flow of coolant.

The food outlet from the heat exchanger 12 is connected to the outlet 17 for the food to be connected to the packaging machine. and an inlet 18 for pressurizing gas.

The resistance heating device according to the invention is illustrated in more detail in FIGS. 2 to 6. . The apparatus consists of pipes assembled in a manner best seen with reference to FIG. A tube 9 having a rectangular cross section is provided.

The tube 9 may be metal, provided with an insulating internal lining plate 20. Equipped with good upper and lower plates 19. As can be seen from Fig. 2, the electrode 21 are embedded in the inner surface of the lining 20.

above the plate 19, the lining 20 and the electrodes 21 if present; The lower assembly is spaced apart by insulating spacer wall members 22. that are the laterally extending upper portions between the laterally extending end portions of the plate 19. and a metal wall member 23 having a lower flange. Porto 24 is Aligned holes in plate 19 are used to hold the assembled parts together in a sealing relationship. It passes through the opening and the flange of the wall member 23.

The exemplary heating device is spaced along its length as best shown in FIG. Includes three pairs of spaced apart electrodes 21, each pole 21 located within the interior surface of the insulating liner 2o. Embedded in the pipe, the internal surface of the pipe is smooth and uninterrupted.

The connection between the power source and the electrode 21 is made by connecting the electrode to the contact plate 37, which is connected from the power source. This is done through an opening 35 in the wall 19 through which the connecting contact member 36 passes.

Each of the three pairs of electrodes shown may be connected between ground and one phase of a three-phase power supply. (The 3-phase power supply is conventional 440 volts, as is standard in the UK.) , 50Hz 3-phase mains power supply, or as standard in other countries. may be equivalent mains supplies, different phases but equal voltages, therefore is applied across the electrodes of each layer.

As shown, the electrodes are all the same length.

If the conductivity of the liquid or other flowable material being processed increases with temperature, More current tends to flow between pairs of electrodes located downstream than between pairs of electrodes located further upstream.

This is due to the fact that the length of the electrode decreases as it goes downstream. t flow consumption can be averaged.

The loft 25 is such that the pipe 9 extends axially and is best shown in FIGS. 2, 5 and 6. A plurality of scraping members 26 and 27 are held. Each scraping member each of the central boss 28, the pair of radially extending arms 19, and the pipe 9; A pair of blades of insulating material adapted to sweep the entire exposed surface area of the wall It consists of a member 30. In the scraping member 26, the radial arm 29 is horizontally , and the blade edge extends vertically. In the scraping member 27, the radial direction The arm extends vertically and the scraping member edge extends horizontally.

Other forms of scraper may be employed, resulting from the force acting on the scraper. Minimizes deflection of itself, prevents material from clogging, and transfers material to the edge of pipe means Preferably, the design incorporates means for directing it from the center to the center.

A rod 25 is attached to the pipe 9 from the upstream end of the pipe 9. 10 through a bushing 31 in the wall. As can be seen in Figure 1, the rod 25 is , here a motor-driven flanges connected eccentrically by a rod 33 to its end. Means for producing reciprocating movement of the mouth 7d, schematically illustrated as a wheel 32 connected to. The distance over which the rod 25 is reciprocated during use is the continuous distance within the pipe 9. overlaps with the area swept by the scraper 27 and likewise the continuous scraper 2 The area swept by 7 must also be such that it overlaps with the first electrode. The total internal length of the pipe from the most upstream down to the most downstream end of the final electrode is therefore It must then be cleared by a scraper acting on all four walls.

The rod 25 is introduced into the device from the upstream end of the heating pipe 9, so that the bush 31 It is not critical to maintain a perfect sterile seal at all times, since The slightest contaminants that may enter the system along the 2nd line are already in the material. This is because the bacterial contaminants that exist in the area and must be sterilized differ only by prefecture. .

This device includes an inlet thermocouple 38, an outlet thermocouple 39, and a control unit ( a flow monitor 40, such as a Doppler flow measurement device, connected to a flow meter (not shown). where the signals from the inlet thermocouple and flow monitor reflect the energy in the heater. Used to obtain the exit signal that defines the voltage application to the electrodes to define the human power It will be done. The signal obtained from the outlet thermocouple 39 is utilized in a feedback loop. , used to refine the temperature control carried out by the control means.

The heat exchangers illustrated in FIGS. 1 and 7 include counters in the path for the coolant fluid. Provides a path for the food to be sterilized through which electrical current is passed. The heat exchanger is split plate 8 , each of whose plates 34 extend from one end of the shell 38 to the other adjacent end. extending to one end and leaving a gap at the other end between the end of plate 34 and shell 38 , each plate 34 is connected to the preceding plate so as to work down the stack of plates. Starting from different ends of the shells 38, the plates extend from the inlet 13 to the outlet 1. 4, providing a tortuous path for the coolant fluid. Space between plates 34 The path for the food to be sterilized within each layer between the plates 34 is and through the space between the ends of the plate 34 and the shell 38. It is provided by a tube configured to pass from one layer to the next. Chew The tube extends through each layer in succession to the outlet from the heat exchanger for the food to be pasteurized. Creates a full flow path through the heat exchanger.

The device according to the invention described above can be used in various ways. heat up quickly or quickly A food product such as milk that needs to be cooled to a temperature is introduced into a holding tank 1 and an inlet 3 Pressurized to a pressure of e.g. 5 atmospheres by air or nitrogen introduced through the The milk may then flow through tube 9 due to the direct path of the current through the milk. is heated when it passes through. The milk then has its outlet in the holding tank shown. can be connected directly to the packaging machine via a pressure reducing valve. The product is then packaged directly into a carton, for example.

For ingredients such as flowable, highly enriched products such as pet food, the product and then simply heated to a higher temperature for the step surface.

This can be achieved by passing the food product into the holding tank 4. There, Canada The warmed coolant coming from the heat exchanger 12 passes through the heating coil 15. heated. The product passes through the switching valve 7 to be introduced into the inlet of the heating device 8 The heating device 8 may be pre-cooked by this heating before heating, and then the heating device 8 is used for heat sterilization. It is specially used to further raise the temperature of food.

The heat extracted by heat exchange B12 is not introduced into the device 8 within the same factory. May be used for other food processing operations such as different food products.

Equipment should be cleaned and sterilized regularly. Such cleaning and disinfection operations In this type of resistance heating equipment, it is customary to rinse it with clean water. It is said that heating cannot be restarted within the tube 9 unless the conductive medium fills the tube 9. This poses a problem. Therefore, following the sterilization process, the device may be exposed to sodium hydroxide or Pipe 9 is filled with a conductive solution such as sodium chloride solution and after the start of resistance heating The introduction of the material to be treated through the inlet 10 of the solution gradually displaces the solution. Preferably, this minimizes wastage of flowable material during machine startup.

As shown, the scraping blade member 30 displaces the flow of liquid within the pipe means. It is slanted in the direction, widening towards the end. Tilt the scraping blade member 30 in the opposite direction. The flow of material brings the scraping blade into close contact with the pipe means. In this way, the flow of material acts against the scraping blade member and within the pipe. More turbulence may be created by creating a deflection in the A further advantage of this construction is that the rod 25 is under tension when it is most loaded. Therefore, the resistance force against buckling load is smaller.

Providing a scraper that acts on the entire internal surface of the pipe to be heated will ensure that the material cooling them when trying to prevent them from sticking to the walls of the pipes (e.g. (as previously proposed in Specification No. 2068200B) is not necessary. Taste. This is also one of the advantages of the exemplary embodiment. Cooling of the pipe wall is naturally This is because it is inconsistent with the general purpose of thermal devices and wastes energy.

The angular cross-section of the pipe 9 allows it to be assembled from flat parts and its For 1. inspections and inspections not possible using traditional circular pipe-based systems. and allows for disassembly for thorough cleaning.

Relatively safe low voltage by using large electrodes running longitudinally of the pipe , thus allowing the use of cheaper and simpler construction methods.

A second embodiment of the resistance heating device according to the invention is shown in FIGS. 8 to 14. , pipe means 109 assembled from five main elements connected by flanges (eighth (see figure). These elements include an inlet end element 201, a first, a second and a second 3 heating elements 202, 203, 204 as well as outlet end element 205. this The structure of these elements is shown in more detail in later figures. It can be seen in Figure 8. In other words, the pipe means 109 has an inlet 110 and an outlet 111.

FIG. 9 shows the middle one 203 of the three heating elements in cross section, the other two are the same It is something. Each has a rectangular cross section as shown in FIG. a pair that abuts the edges of the spacer wall member 123 and is separated by them; facing exterior wall members 119 . These wall members of the pipe means aluminum A sealing gasket is provided, preferably a sealing gasket, in which the spacer wall member 123 comes into contact with the wall member 119. Directly inside the wall member 119 is a spacer wall. Insulating spacing lining plate 122 lying directly inside member 123 More spaced insulating lining plates 120 are provided. electrode 12 1 appears to be embedded in the inner surface of each of the lining plates 120. In addition, each surface is flush with the boundary surface of each lining plate 120. It's on the surface. Bolts 124 passing through openings in wall members 119 and 123 a spacing lining plate 122 so as to seal the inner chamber body of the pumping means; In contrast, it acts to compress the lining plate 120. to improve sealing a groove running longitudinally along each edge of the spacing lining plate 122; 206 is provided.

As seen in the cross section, a set of four parallel rods 12 placed at the corners of a rectangle 5 extends from the inlet end to pipe means 109.

Four rods are installed in the outer plate 207 of the inlet end of the pipe means. (FIG. 13), the single rod 208 is separated from the rod 125 and the plate 2 07 and extends parallel to it.

The rod 125 is arranged so that it can be reciprocated by the movement of the rod 208. It enters the pipe means through a bush in the end plate of the pipe means.

A carrier 209 holding a scraping blade 210 is mounted on each of the rods 125. Supported at even intervals. Carriage 2Q9 generally receives respective rods 125. The hole has a diameter such that each scraping blade 210 is installed. It is spherical with a protruding neck. The scraping blade 210 scrapes the paper in the direction of flow. 109, scraped off the wall with built-in electrodes, and left a space there. Provided for alternating scraping of walls.

The length of the wand 1250 cage's reciprocating motion depends on the scraping brake acting on a particular wall. The working area of the door 210 is such that the internal area of the pipe means within the heating area is left scraped. It is enough to overlap so that

A cage of four rods 125 may be used to hold the scraping blade. The blade is pressed against the wall for scraping and has a natural spring action. It will be done.

Intermediately between the counter electrodes 121 and at regular intervals along the pipe means, the insulating shield members 2 11 are provided. Four such shield members are provided. The first one is , an inlet end element 201 overlapping the upstream portion of the electrode of the first heating element 201 Extends from within. The second one overlaps the upstream end of the electrode of the second heating element 202 , extending from a position overlapping the downstream end of the electrode of the first heating element. the third one The second heating element 203 overlaps the upstream end of the electrode of the third heating element 203. It extends from the overlapping portion of the downstream end of the electrode 02. The last one is inside the exit element 204 Extending from the overlapping portion of the downstream end of the electrode of the final heating element 203 to. each shield The members are arranged in opposing longitudinal directions within the interior surface of the spacing lining plate 122. It is a relatively thin plate of insulating plastic material bridging between grooves that run in the middle. uk As more fully disclosed in patent application no. 8809750.6, the shield portion The purpose of the material is to reduce the tendency for current density to increase at the upstream and downstream edges of the electrode. The second is to reduce the current path at and around the edges of the electrodes. the result, The current density at these edges is substantially higher, as in the absence of the shielding member. The electrode can be run at a higher average current density than is possible when .

It can be seen that the shielding member covers approximately 70% of the area of the electrode.

In the area where the lining plate 122 holds the shield member 211, When the scraping blade 210 is arranged to scrape the inner surface of the plate, the The scraping blade 210 is interrupted to accommodate the presence of the shield member 211. Ru. In other areas, the scraping blades are bridged between pairs of carrier members 209. There is.

Lining plates 121 and 122 are made of polyether sulfone or polyester. Made of moisture-resistant, food-approved plastic material, such as ether ether ketone. is preferred, and the electrode is of a coating known in the art, such as Eltic EC610 coating. It is preferably titanium coated with a suitable electrode coating such as The electrode and the wall in which it is received should be In the illustrative embodiment, it is problematic to provide a joint with the lining plate. The sheet 120 is configured to receive the electrode 121 while in the vertically stretched state. is machined and then loosened against the edge of the electrode, so that the The difference in thermal expansion between the poles and the lining plate then causes the inside of the lining plate 120 to The elastic stress is adjusted by varying the elastic stress and thus the edge of the electrode and the lining plate 1 The opportunity to open the gap between 20 and 20 minutes can be avoided.

This is achieved by the method best described with reference to Figures 11 and 12. will be accomplished. As shown in FIG. 12, the wall member 119 of the pipe means A pair of abutment members 212 are provided at the ends, which are placed on the inner surface of the wall member 119. There is. At opposite ends of the wall member 119, a pair of screw-adjustable abutment members 213 are attached to the wall member 119. An adjustment screw 214 is provided at the end of the material 119 connected to an adjustment screw 214 extending through the flange. Ru. The lining plate 120 has a A recess is provided in the wall member 119, and the lining plate is disposed in contact with the wall member 119. After that, the abutment part 213 elastically holds the lining plate 120 in the direction of flow of the device. It is tightened with a screw on the outside so that it can be pulled. The opening for receiving the pole 121 is The electrodes 136 and stacks are then machined within the lining plate 120. The lining plate 12 has holes for receiving a plurality of electrodes on which the electrodes 213 are installed. A hole is drilled inside 0. The electrode is then attached to the stud 21 held by the electrode 121. 3 and the stud 213 is insulated by an insulating collar. It is fixed with a nut on the outside of the wall member 119. This connects the electrode to the flat against the inner surface of the holding plate 120.

The adjustment screw 214 of the movable abutment 213 is then loosened, thereby The ends of the poles 121 and the electrodes in the lining plate 120 (the ends of the recesses and As the elastic stress within the lining plate 120 is released, the joint between the made to close.

The inlet end element of the pipe means 109 shown in FIG. Consists of a circular end plate 215 and a circular external wall 214 through which a bushing 125 is passed. Has an outer metal casing. The downstream end of wall 214 is connected to the first heating element 202. PTFE 216 within the 0 cylindrical wall 214 which is a flanged skirt at the upstream end. blocks are provided.

The downstream end element 204 shown in FIG. 14 generally includes rods 125 that mirror the end element. It has the same structure, except for the course that does not pass through the plate.

The outlet tube 217 extends from the end plate of the end element 204 and is in an electrically insulating relationship. It is flanged to the inlet tube 21B of the cooling device.

Power to the device is provided by a 6-pulse rectifier system or by a central neutral single phase transformer or takes the form of an inverter powered by a 6-phase electric filter. They are pipe hands The electrodes on one side of the stage are powered by a power supply symmetrical to the neutral point, which may be individually amplitude controlled. The neutral collector electrode is provided with a connector terminal 219. The downstream end element 205 is configured by the end face of the downstream end element 205. The most downstream of the shield member 211 that extends into the end element 205 to overlap the downstream edge of the last pair of electrodes and It is clear from FIG. 14 that the short circuit of the sex point collector electrodes is stopped.

Heating control in a flowable product heater is achieved by applying a voltage to one or more pairs of electrodes. This can be achieved by changing the amplitude of

For control purposes, one or more pairs of electrodes may be switched off momentarily.

Also, when there is a potential difference, the current flow from adjacent electrodes on the same side of the pipe means On the other hand, only a thin piece of the electrode is scraped off, and the electrode part where the material is exposed is exposed to a high electrical load. If there is a potential danger, the position of the scraping member can be sensed and the resulting hand to momentarily cut off the power at potential critical points to protect the electrodes. It can include steps.

The effects of using the above-mentioned shield member are illustrated in FIGS. 15 and 16, and they are , a plot of equipotentials produced by a computer simulation.

FIG. 15 shows that in normal use there is virtually no current between the electrodes on the same side of the pipe means. does not flow, and the ratio of the maximum current density at any electrode to the average current density is approximately 1.5, which means that the average current density is too high and the edge current density is too high. This means that it can be much higher than in the presence of a shield that never becomes Ru.

The heating effect is greatest when the equipotentials are closest, therefore the heating effect is It can be seen that it is highest along the central axis of the heater. fL movable material along central axis current distribution results in more uniform heating because the current can flow as fast as possible there is a possibility. Furthermore, the positioning of the shield along the central axis is itself This tends to reduce the flow rate along the center of the heating means, again ensuring uniform heating. Help the sea urchin.

Figure 16 shows an example of the situation that occurs instantaneously when the current is switched off at the center electrode. Show. The plot shows the current flowing between the upstream and downstream electrodes and the center pair of electrodes. Indicates that the current is not too high and also that the maximum current at the upstream and downstream pair of electrodes Ensure that the current density does not become too high even under these conditions in proportion to the average current density. Also shown.

Both plots show that there is virtually no flow of current into the neutral electrode at the end of the pipe means .

The advantages of the scraping system described with reference to Figures 8 to 14 are that Obstacles to the flow of the means are reduced compared to the mechanisms illustrated in FIGS. 1 to 7. It is also reduced. This is a relatively long arm that extends perpendicular to the flow direction. This is because the existence of Flowing material may become clogged, resulting in risk of overheating. This design is superior in that it avoids areas where The scraping member has a long support. Because of the holding rod, it is built into contact with the surface to be scraped with light force. It also functions as a spring.

The scraping element acts on all these areas of the pipe means boundary area where heating occurs. do. The design also ensures that the interior of the pipe means is exposed to the flowable medium being heated. and is not scraped as in end element 204, the flow is accelerated and It tends to prevent adhesion to parts.

The device design of Figures 8-14 is suitable for heating flowable materials of different conductivities. such as to facilitate adjustment of the equipment for treatment. Hold the shield member vertically The exemplary system can be used to shift or mask the electrodes to different degrees. by removing the shield members and replacing them with shield members of different lengths. and may be heated in the pipe means with any power based on any current limitations on the power supply. It is possible to vary the minimum or maximum resistivity of the flowable material.

Although the invention has been illustrated by the description of specific embodiments, it is contemplated that many modifications may be made within the scope of the invention. and it should be recognized that changes are possible.

Mi Procedural amendment (formality) January 19, 1990

Claims (11)

[Claims] 1. Apparatus for resistive heating of an electrically conductive flowable medium, the apparatus comprising: pipe means (9) which can be arranged to flow through the pipe means (9); ) has a sufficiently low conductivity so that resistive heating of the flowable medium is provided there during use. made from or internally aligned with electrically conductive materials (20, 21) and, furthermore, in use with the medium spaced within the pipe means and flowing through it. comprising at least two electrodes (21) arranged in electrical contact, the device comprising: electrodes, and the tendency, if any, to adhere thereto from flowable materials when heated. Heating a flowable medium so as to remove or deflect some material therefrom in contact with a flowable medium in one or more zones within the pipe means that occur during use. movable within said pipe means, such as for use on internal wall surfaces of said pipe means; resistively applying a conductive flowable medium characterized in that it comprises means (25, 26, 27); A device for heating. 2. The movable removal means is a scraper, which scrapes the contact with the interior of the pipe means. Claim comprising one or more scraping members (26, 27) installed for removing The device according to item 1. 3. The scraper is attached vertically to the pipe means connected to the reciprocatable carrier member (25). A plurality of scraping members (26, 27) are provided at intervals in the direction, a part of which is , extending from the upstream end of the pipe means and for reciprocating said scraping member. 3. Device according to claim 2, connected to means (32, 33) of. 4. a reciprocatable carrier member comprising a cage of elongated carrier means (125); At least some scraping members (21 4. The device of claim 3, comprising: 0). 5. Said means for removing material from the interior of the pipe means is capable of resistive heating during use. The preceding claims are made to operate over substantially the entire resulting length. The device described in any of the above. 6. Said electrodes (21) form one or more electrode pairs, the members of each pair of electrodes being mutually across the pipe means and facing the width thereof, as claimed in any of the preceding claims. equipment. 7. Each electrode (21) is substantially identical to the area of said surface adjacent to the respective electrode. embedded within the internal surface of the pipe means so as to be in one plane. 6. The device according to 6. 8. All of the electrodes are exposed for current flow over 30% of the internal surface area. Apparatus as claimed in any of the preceding claims, having a surface area presented. 9. The pipe means is straight and of hollow rectangular cross section, and the internal surface of the pipe means A device according to any of the preceding claims, wherein the is substantially flat. 10. A movable removal means is installed for scraping the contact with the inside of the pipe means. , and the transit time through the pipe means for all flowable materials is substantially Stir the flowable material or stir it in a turbulent manner to ensure a uniform flow. A device according to any of the preceding claims, which is a creper. 11. Apparatus for resistive heating of an electrically conductive flowable medium, the apparatus comprising: a pipe means (9) which can be arranged to extend therethrough; , conductivity low enough so that, during use, resistive heating of the flowable medium is imparted therein. (20, 21) or internally aligned therewith. and further spaced within the pipe means and in use electrically connected to the medium flowing through it. at least two electrodes arranged to touch each other, the device The flow rate is such that the transit time through the pipe means for the functional material is substantially uniform. including means (25, 26, 27) for stirring or creating turbulence of possible materials; Apparatus for resistive heating of an electrically conductive flowable medium, characterized in that: