Nielsen, Karsten (Arendalsvej 96, Silkeborg, DK-8600, DK)
Kjeldsen, Poul (Jeppe Åkjærsvej 33, Ebeltoft, DK-8400, DK)
Nielsen, Karsten (Arendalsvej 96, Silkeborg, DK-8600, DK)
| 1. | A method for scalding slaughtered poultry, by way of example chickens, turkeys, ducks or geese, where the poultry is transported through a scalding tunnel after slaugh tering, preferably suspended at the feet, where the poultry in the scalding tunnel is conveyed successively between rows of nozzles that are adapted to apply scalding agent to the poultry, characterised in that a plurality of different scalding agents are applied, that in a first scalding zone hot water is used as scalding agent, that in suc¬ ceeding scalding zones scalding agents with mutually differing temperatures are ap plied, that in the said succeeding scalding zones warm humid air is used as scalding agent which is at least blown onto specific sub areas of the poultry. |
| 2. | Method according to claim 1, characterised in that the poultry is then conveyed between additional rows of nozzles in an additional scalding zone where warm humid air is blown at least on the remaining sub areas of the poultry. |
| 3. | Method according to claim 12, characterised in that after passing through the firstmentioned scalding zones, the poultry is passed through a primary plucking sta¬ tion, where feathers are plucked from the firstmentioned specific subareas of the poultry, and that the poultry, after passing through the additional scalding zone, is passed through a secondary plucking station where the remaining feathers are plucked from the poultry. |
| 4. | An apparatus for use in the method according to claim 1 and including a largely closed scalding tunnel with a conveyor that runs past a system of nozzles which are arranged to apply scalding agent on the poultry, characterised in that the scalding tunnel includes a first scalding zone with rows of nozzles that are adapted to spray hot water on the poultry, and succeeding scalding zones which are adapted to work with different temperatures of the scalding agent, and which are designed with a system of nozzles that are arranged for blowing warm humid air on specific sub areas of the poultry. |
| 5. | Apparatus according to claim 4, characterised in that the temperature of the scald ing agent in a first of succeeding scalding zones is about 60°C, and that the tempera¬ ture of the scalding agent in a second of the succeeding scalding zones is about 50°C. |
| 6. | Apparatus according to claim 4 and 5, characterised in that after the first of the succeeding scalding zones, it includes a first plucking station which is adapted for plucking feathers from the firstmentioned specific sub areas of the poultry. |
| 7. | Apparatus according to claim 4 and 5, characterised in that after the second of the said succeeding scalding zones, it includes a second plucking station which is adapted for plucking the remaining feathers from the poultry. |
| 8. | Apparatus according to claims 47, characterised in that the system of nozzles in the succeeding scalding zones includes movable and individually controllable nozzles which are adapted to follow the poultry at least over a subdistance of the scalding zones. |
| 9. | Apparatus according to claims 48, characterised in that movable nozzles are de¬ signed in elongated cylindric drums that are rotated about a horizontal axis, so that the discharge openings of the nozzles are moved along the poultry in the direction of con veying of the latter. |
| 10. | Apparatus according to claims 48, characterised in that individually controllable nozzles are designed in elongated cylindric drums which are rotated about an inclining axis, so that the discharge openings of the nozzles are moved in vertical direction as well as in horizontal direction relative to the direction of conveying of the poultry. |
Field of the Invention The present invention concerns a method for scalding slaughtered poultry, by way of example chickens, turkeys, ducks and geese, and of the kind specified in the preamble of claim 1.
The invention also concerns a system for scalding slaughtered poultry according to the method according to the invention.
Background of the Invention In order to scald slaughtered poultry prior to plucking with regard to facilitating the subsequent plucking, it is prior art to convey poultry suspended at the feet through an elongated tank with hot water, possibly combined with injecting air in the scalding vessel through lower nozzles.
By a second prior art method, the poultry is transported successively and suspended at the feet in a conveyor via an inlet sluice through a closed scalding chamber, in which the atmosphere is heated by means of vapour-saturated air which is injected into the chamber and directly upon the poultry. The advantages of applying vapour-saturated air are significant energy savings and a very substantial reduction in dissemination of bacteria, as the poultry are not submerged in a water bath and do not come into direct mutual contact.
Besides, an improved working climate is achieved in the surrounding plucking room as a consequence of a much reduced production of vapour. The poultry is to stay a certain time in the closed scalding chamber, determined by the length and the course of the conveyor belt in the scalding chamber and of its capacity and/or speed. In order to utilise the space in the scalding chamber optimally, the conveyor belt runs in paral¬ lel tracks back and forth inside the scalding chamber in the same or at plural levels.
EP-Al-I 297 748 describes a method and an apparatus for scalding poultry where, by means of a primary system of nozzles at the bottom of the scalding chamber, saturated steam is injected which is used for producing humid hot air that is sucked out at the top in the scalding chamber and re-injected directly upon the poultry by means of a secondary system of nozzles. Even if saturated steam is used for heating the scalding air, by this method it is possible anyway to work with a low scalding temperature of about 50°C or with a higher scalding temperature of about 6O0C, as the poultry is not at any time subjected to the direct action of saturated steam.
WO 03/088751 also describes a method and an apparatus for scalding slaughtered poultry before plucking thereof, where the poultry suspended at the feet is transported via a sluice device through a scalding chamber, wherein, by injecting steam into the scalding chamber, there is established a precisely controlled heated atmosphere of humid hot air which is recycled and injected directly onto the poultry, and where the scalding period is determined by the length and the course of the conveyor and of its capacity and/or speed, where a scalding chamber with relatively great height is used, and that the conveyor of the scalding chamber with associated secondary nozzles run through two or more levels (storeys).
Object of the Invention On that background, it is the purpose of the invention to indicate a further improved method and a further improved system for scalding slaughtered poultry of the kind specified in the preambles of claim 1 and 4, respectively, and which enable further optimisation of the scalding with the intention of achieving subsequent optimal pluck¬ ing, to avoid unnecessary heat action on the poultry and to attain further reduction of the energy consumption.
Short Description of the Invention The method according to the invention is characterised in that different scalding agents are applied, that in a first scalding zone hot water is used as scalding agent, that in succeeding scalding zones scalding agents with mutually differing temperatures are applied, that in the said succeeding scalding zones warm humid air is used as scalding agent which is at least blown onto specific sub areas of the poultry. In a simple way is hereby achieved possibility of further optimising the scalding, so that optimal pluck¬ ing may occur subsequently without the poultry subjected to unnecessary heat action, and so that a considerable reduction of the required energy consumption is attained simultaneously. With the purpose of achieving the best possible effect of the humid, hot air, it is of great significance that temperature, pressure and amount of scalding agent are cor¬ rectly adjusted for scalding the said specific sub areas of the poultry, so that softening of follicles and the subsequent plucking of feathers from the said specific sub areas of the poultry are also optimised. It is furthermore advantageous that in a first scalding zone, hot water is used to preheat and flush the feathers of the poultry free from dust and fat, so that the follicles may be softened more efficiently by applying scalding agent in the form of warm humid air in the succeeding scalding zones.
The most difficult sub areas on the poultry are - when speaking of plucking feathers - the tail region and top sides of wings, why these areas are to be applied the greatest amount of scalding agent in the form of warm humid air at the highest temperature. On other sub areas of the poultry, it is considerably easier to pluck off the feathers, i.e. follicles in these sub areas do not require so intensive softening. In other words, very substantial amounts of energy may be saved by controlling and optimising the supply and the temperature of the scalding agent to respective sub areas of the poultry.
It is to be mentioned that it may be advantageous that the poultry during its passage through the scalding tunnel is turned relative to the direction of conveying, i.e. so that the wings of the poultry are angularly turned in relation to the direction of transport. Hereby may be achieved that the poultry may hang closer without the wings coming into mutual contact. In other words, the capacity of a scalding tunnel may be increased by angular turning of the wings of the poultry, as the mutual hanger spacing may be reduced thereby. In this connection it is important to point out that due to risk of infec¬ tion, individual poultry must not come into direct contact with other poultry during the passage of the scalding tunnel.
The method according to invention is suitably further modified in that the poultry is then conveyed between additional rows of nozzles blowing warm humid air at least on the remaining sub areas of the poultry. In a simple way is hereby achieved that the sub areas of the poultry, which are the most easy to pluck the feathers from, are also treated most gently by minimising the harmful heat action on respective sub areas of the poultry. The method according to the invention is most suitably further modified in that after passing through the first-mentioned row of nozzles, the poultry is passed through a primary plucking station, where feathers are plucked from the first-mentioned specific sub-areas of the poultry, and that the poultry, after passing through the additional rows of nozzles, is passed through a secondary plucking station where the remaining feath¬ ers are plucked from the poultry.
The invention also concerns an apparatus for use in the method according to the inven- tion and including a largely closed scalding tunnel with a conveyor that runs past a system of nozzles which are arranged to apply scalding agent on the poultry, the appa¬ ratus being characterised in that the scalding tunnel includes a first scalding zone with rows of nozzles that are adapted to spray hot water on the poultry, and succeeding scalding zones which are adapted to work with different temperatures of the scalding agent, and which are designed with a system of nozzles that are arranged for blowing warm humid air on specific sub areas of the poultry.
The apparatus according to the invention is suitably designed so that the temperature of the scalding agent in a first of succeeding scalding zones is about 6O0C, and that the temperature of the scalding agent in a second of the succeeding scalding zones is about 50°C.
With the intention of minimising the required heat action on the poultry and for the best possible utilisation of the gentle, though purposeful softening of the specific sub areas of the poultry, the apparatus according to the invention may advantageously be designed so that after the first of the succeeding scalding zones, it includes a first plucking station which is adapted for plucking feathers from the first-mentioned spe¬ cific sub areas of the poultry.
With the purpose of optimising also the plucking of feathers from the remaining sub areas of the poultry, the apparatus according to the invention may advantageously be designed so that after the second of the said succeeding scalding zones, it includes a second plucking station which is adapted for plucking the remaining feathers from the poultry. With the intention of optimising supply of the scalding agent to specific sub areas of the poultry, the apparatus according to the invention may suitably be designed so that the system of nozzles includes movable and individually controllable nozzles which are adapted to follow the poultry at least over a sub-distance of the scalding zones.
The apparatus according to the invention may furthermore advantageously be de¬ signed so that the movable nozzles are designed in elongated cylindrical drums that are rotated about a horizontal axis, so that preferably helical discharge openings of the nozzles are moved along the poultry in the direction of conveying of the latter.
As a supplement, the apparatus according to the invention may furthermore be de¬ signed so that the individually controllable nozzles are designed in elongated cylindri¬ cal drums which are rotated about an inclining axis, so that preferably helical dis- charge openings of the nozzles are moved in vertical direction as well as in horizontal direction relative to the direction of conveying of the poultry.
Short Description of the Drawing The invention is explained more closely in the following with reference to the draw- ing, on which:
Fig. 1 shows a vertical section through a scalding chamber known from the above mentioned EP-Al-I 297 748;
Fig. 2 shows a horizontal side view and a vertical section through a second scalding chamber known from the above mentioned WO 03/088751 ;
Fig. 3 shows a longitudinal section through an embodiment of a scalding tunnel according to the invention;
Fig. 4 shows an elementary sketch in perspective view of an embodiment of a blower arrangement with common manifold for distributing the humid warm scalding air to several nozzle sections of a scalding tunnel according to the invention; Fig. 5 shows a elementary sketch of in perspective view of an embodiment of a noz¬ zle arrangement with two rotating elongated helical discharge or nozzle open¬ ing according to the invention;
Fig. 6 shows an embodiment of a flow diagram of a primary steam system by a scalding tunnel according of the invention;
Fig. 7 shows an embodiment of a flow diagram for a secondary steam system ac¬ cording to the invention;
Fig. 8 shows an embodiment of a flow diagram of a manifold system for controlling and distributing the scalding means in the form of humid warm air for a scalding tunnel according to the invention;
Fig. 9 shows an embodiment of a flow diagram for a primary and a secondary water distributing system for a scalding tunnel according to the invention;
Fig. 10 shows two views of an alternative embodiment of elongated pivotable slotted nozzles for controlled application of scalding agent to specific sub areas of the poultry, e.g. the tail region, during its passage through a scalding tunnel according to the invention; and
Fig. 11 shows a horizontal section through a preferred embodiment of a scalding tun¬ nel according to the invention; and
Fig. 12 shows a vertical section through the preferred scalding tunnel shown in Fig. 11.
Detailed Description of the Invention The apparatus or scalding tunnel 10 according to the invention includes, as it appears from Figs. 3 and 4, centrifugal blowers 14 which are built into the ceiling of the scald¬ ing tunnel 10, that is which have horizontal ventilator wings driven by vertically dis¬ posed motors 16, which is different from the prior art scalding chambers or scalding tunnels 2 shown in Figs. 1 and 2, where centrifugal blowers 5 are mounted separately upon the scalding chamber or the scalding tunnel 2.
The apparatus or the scalding tunnel 10 according to the invention also uses the same heating principle for the scalding agent, which is shown in Figs. 1 and 2, as the scald- ing means in the form of warm humid air is produced by injecting vapour-saturated steam in a lower part of the scalding tunnel 10 by means of a primary system of noz¬ zles. Subsequently, the warm humid scalding air is evacuated by means of the cen¬ trifugal blowers 14 which then re-inject the scalding air directly onto the poultry which passes through the scalding tunnel 10 suspended by the legs by means of hang- ers in a conveyor track 12.
The conveyor 12 runs through a first scalding section 16 of the scalding tunnel 10 shown in Fig. 3 in three mutually parallel tracks 18 that run between a system of noz¬ zles arranged to blow warm humid air directly on specific sub areas of the poultry be- fore it is conveyed through a primary plucking station 20, where feathers are plucked off from at least the said specific sub areas of the poultry. These sub areas may e.g. consist of the tail region of the poultry and top sides of wings, where follicles are most difficult to soften with the object of mechanised plucking of feathers. Then the poultry is continued on the conveyor track 12 through a second scalding section 22 in which the poultry, also in mutually parallel tracks, passes between a second system of noz¬ zles which are arranged to blow warm humid air on the remaining parts of the poultry, which then passes yet a plucking station (not shown) where the remaining feathers are plucked by machine.
Fig. 4 shows how the centrifugal blowers 14 are built into the ceiling of the scalding tunnel 10, and how four centrifugal blowers 14 via a common manifold 24 supply a very large number of not shown injection nozzles.
Fig. 5 shows an embodiment of a special nozzle arrangement 26 with two rotating elongated cylindrical drums 28 with helical discharge or nozzle openings 30. Accord¬ ing to need, the nozzle arrangement 26 may be mounted horizontally in relation to the direction of movement of the poultry through the scalding tunnel 10, i.e. so that the discharge or nozzle openings 30 follow the poultry by rotating the drums 28 and blows scalding agent upon the poultry over a length determined by the length of the nozzle arrangement 26.
Alternatively, the nozzle arrangement 26 may be mounted at an oblique angle in rela¬ tion to the vertical or the horizontal so that the nozzle opening 30 may be moved both in horizontal and in vertical direction compared with the direction of movement of the poultry during its passage past the nozzle arrangement 26.
Fig. 6 shows a flow diagram for the primary steam system, where steam is let in at BO.00 and passes a filter B2.00, a flowmeter (steam volume) OB3.00. Downwards, a condensate separator B9.00 is arranged. The primary steam flow passes a pressure control valve B5.00, where after the steam is divided into two main streams with each their motor-operated valve B8.00/Z8.00, from where the steam is conducted to each their nozzle group B 15.00/Zl 5.00 which is also shown in Fig. Between the pressure control valve B5.00 and a T-branch to the motor-operated valve B8.00/Z8.00 there is provided a branch from the primary steam flow, so that high-pressure steam may be conducted to respective tunnel sections with the purpose of controlling the tempera¬ ture of the scalding agent via branches B13.00/Z13.00, as well as steam may be drawn off via a separate branch B14.00 for optional separate scalding of the feet of the poul¬ try.
Fig. 8 shows a flow diagram for two manifold systems for distributing controlled scalding agent in the form of warm humid air to each their section B and Z of scalding tunnel 10, where admixing of extra water via the valve groups B25.00/Z25.00 (Fig. 9) and each their hose branch may be effected directly down into the tangentially ar- ranged discharge pipes which are directly connected with the injecting nozzles, and which each additionally comprise the motor-operated valves B31.00-31.07/Z31.00- 31.07 that are each controlled via control wires from common terminal strips B3O.OO/Z3O.OO (only the control wires from terminal strip B30.00 to B31.00-31.07 are shown at the bottom of Fig. 8).
B40.00/Z40.00 are temperature sensors that measure the temperature in respective sections of scalding tunnel 10. B41.00/Z41.00 are temperature sensors showing the actual temperatures of scalding agent, while B42.00/Z42.00 are humidity sensors showing the actual humidity of the scalding agent. Fig. 9 shows an embodiment of a flow diagram of a primary and secondary water dis¬ tribution system, where B20.02 is a water pump supplying water at 4-8 bar, where B22.00/Z22.00 are solenoid valves for each their group B24.00/Z24.00 of water atom- ising nozzles for respective sections of scalding tunnel 10. The water atomising noz¬ zles are disposed on the tunnel wall above the steam nozzles and serve to regulate the actual humidity of the warm scalding air.
Fig. 10 shows two views of an alternative embodiment of elongated pivotable slotted nozzles for controlled supply of scalding agent to specific sub areas of the poultry, e.g. its tail region, during its passage through a scalding tunnel according to the invention.
The preferred embodiment of a scalding tunnel 32 shown in Figs. 11 and 12 includes a first scalding zone 34 provided with a system of nozzles 36 which is adapted to spray hot water (52-6O0C) on the poultry with the intention of preheating and flushing the plumage free from dust and fat so that the softening of the follicles of the poultry be¬ comes more efficient in the succeeding scalding zones, where warm humid air is used for softening follicles of specific sub areas of the poultry.
With the intention of optimising energy saving, the warm flushing water is collected at the bottom of the scalding tunnel 32, so that it may be reused together with the con¬ densate from the subsequent nozzles supplying warm humid air on specific sub areas of the poultry.
In that connection, it is important to point out that no risk of infection occurs by using and reusing warm water for spraying on the poultry, as this occurs before the plucking, i.e. before follicles are exposed.
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