GB2452707A

GB2452707A - An improved steam injector

Info

Publication number: GB2452707A
Application number: GB0717603A
Authority: GB
Inventors: David Norris
Original assignee: DC Norris and Co Engineering Ltd
Current assignee: DC Norris and Co Engineering Ltd
Priority date: 2007-09-10
Filing date: 2007-09-10
Publication date: 2009-03-18
Anticipated expiration: 2027-09-10
Also published as: GB0717603D0; GB2452707B

Abstract

A method of processing flowable food product within a cooking vessel, comprises injecting steam into the vessel by means of an injector 2 including a body having sections 6, 8. The body is provided with an internal chamber 19 to which the steam is supplied. Steam escapes from the chamber by way of an outlet in the form of an annular slot formed when a valve head 13 is displaced relative to the body under pressure of steam. In the region of the slot the body section 6 is so shaped that steam leaving the slot adheres to that surface and promotes circulation of the food product by virtue of the Coanda effect, as well as heating the food product.

Description

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IMPROVEMENTS IN OR RELATING TO THE PROCESSING OF

FLOWABLE FOOD PRODUCTS

This invention relates to the heating and circulating of flowable food products contained in a cooking vessel It s well known to inject steam into a cooking vessel n order to cook or partially cook its contents. A problem with certain known steam injectors is that they generate unacceptable noise, i.e. the so-called "steam hammer" effect. To overcome this problem, patent specification GB No. 2 106 800A ("Giusti") discloses admixing air with the steam before injection into the vessel The injection system described by Giusti is incorporated into the bottom of the vessel which leads to problems when cleaning has to take place. Moreover, a separate arrangement is needed in order to stir the contents of the vessel. Patent specification EP1 549 856 Bi (Pursuit Dynamics") discloses the use of a steam injector in the form of a fluid mover having a straight-through passage into which steam is admitted through an annular slot-like nozzle The steam causes the contents of the vessel to flow through the passage of the flud mover and be heated and recrcu!ated, It s fundamental to the injector disclosed by Pursuit Dynamics that a supersonic shockwave be created within the fluid mover. This leads to the production of noise and may also have an adverse effect on certain constituents of a food product, for example, starches Moreover, the necessity for the food product to pass through a passage of a fluid mover of the type proposed by Pursuit Dynamics in order to cause the product to circulate leads to problems in the processing of certain bulky food products, such as individually quick frozen foods (IQF), because of the constricted nature of the passage. Moreover, certain food products, such as long pasta, may be broken when passing through the fluid mover The present invention seeks to overcome these problems.

Accordingly, the method of processing a flowable food product disclosed hereinafter makes use of an injector provided with an internal chamber to which the steam is supplied. Steam escapes from the chamber by way of an outlet in the form of an annular slot formed when the head of a valve is displaced relative to the injector body under pressure of steam At least in the region of the slot the external surface of the body is so shaped that steam leaving the slot adheres to that surface and promotes circulation of the food product by virtue of the Coanda effect, as well as heating the food product The valve may be arranged to open against spring pressure when steam is admitted to the chamber within the injector body. Means may be provided for restricting the travel of the valve which takes place under the pressure of steam so as to determine the width of the slot which forms when the valve opens The injector may be mounted on a lance which extends into the cooking vessel and through which steam is fed to the injector.

Broadly stated, an injector for use in carrying out the method includes a body provided with an internal chamber to which steam may be supplied, an outlet from the chamber in the form of an annular or part-annular slot disposed at the forward end of the body, the slot being bounded by a lip which diverges progressively from the axis of the slot and extends in the rearward direction relative to the injector body In the drawing Fir,iirp I lliictrt tPrfl IflIQttrr in nr1nr th rfrrri rrhniment of

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in.,.,,. ;,;,-,......,..,... ....-..a LI! P YI P(I'.JI I UI.JFJL..II LU VI Q II Figure 2 is an axial section through the injector, and Figure 3 is a perspective view of the injector, pertly in axial section, Referring to the drawing, a steam injector 2 is mounted on the end of a hollow lance 4 connected to a source of steam. A valve (not shown) is provided to enable the supply of steam to be controlled.

The injector includes a generall, barrel-shaped body 3 of circular cross-section having forward and rearward body sections 6 and 8, respectively The rearward end of body section 6 has a cylindrical boss 6a which is received within a recess of corresponding shape in the forward end of body section 8, the two sections being secured together by screw threaded or other suitable means. An annular groove in the edge of the boss receives the periphery of a disc 10 having an extended centre piece through which extends an axial bore for receiving and locating the stem 12 of a valve head 13. A seal 7 is interposed between the two body sections. The rearward body section 8 encloses a chamber 14. An inlet opening 16 at the rearward end of the body section 8 is provided with a screw-thread 18 to enable the injector to be mounted on the lance. The forward body section 6 encloses a chamber 19 which communicates with the chamber 14 by way of openings 20 in the disc 10. The chamber 19 has a mouth at its forward end which is normally closed by the valve head 13 bearing against the forward extremity of body section 6 where it surrounds the mouth A compression spring 22 is located between the disc 10 and a stop 24 carried by the valve stem 12. Nuts 25 on a screw-threaded extension of the valve stem serve to adjust and fix the position of the stop 24 relative to the rear surface of the disc 10 and to set the gap indicated at 26 between the forward end of the stop 24 and the disc 10.

The size of the gap 26 between the stop and the disc determines the distance through which the valve head 13 travels in the forwards direction when it opens.

When the valve head is in its forward position an annular slot is formed which surrounds the periphery of the valve head The slat is bounded on its radially inner side by the planar peripheral edge portion of the rearward surface of the valve head On its radially outer side the slot is bounded by a convexly curved lip 29 constituted by part of the forward extremity of the body section 6 The outer surface of the lip 29 therefore continuously and progressively recedes and diverges relative to the ax's of tue lu In use, the lance is supported so as to extend into a cooking vessel containing a flowable food product. Steam is supplied to the lance and flows through chamber 14 into chamber 19 where it acts on the valve head 13, displacing it to the left and opening the slot surrounding t where indicated at 27 The curvatures of the lin 29 bounding the outer side of the slot as well as of the surface rearwardly of the lip are such that steam issuing from the open slot flows rearwardly and is caused by the Coanda effect to adhere to the surface of the lip and the surface of the body to the rear of the lip. In consequence a drop in pressure takes place in the region which surrounds the steam injector Food product is drawn into the low pressure region and flows towards the rear of the injector A transfer of heat from the steam to the food product takes place during this process. Circulation of food product within the cooking vessel is thereby promoted and an even heating arid cooking effect achieved.

The pressure of steam supplied to the injector may be determined by trial and error.

By adjusting the gap 26 between the disc 10 and stop 24 it is possible to vary the width of the slot formed when the valve is opened so as to achieve optimum flow conditions through the slot and along the body of the injector in dependence on steam pressure. The width of the slot corresponds to the gap 26. The width of the slot may be determined by trial and error but is thought to be desirably set at less than substantially 1.2 mm, as it has been found that an unacceptable level of noise may be generated with wider slots, depending upon steam pressure. It is believed that an optimum width of the slot is substantially 0.6 mm.

The steam injector disclosed herein has a number of advantages In particular it is able to operate much more quietly than the known systems, in particular in comparison to that disclosed by Pursuit Dynamics Because the slot through which steam is injected into the food product closes when steam pressure falls below the valve opening pressure, there is a reduced risk of internal contamination. Certain food products which cannot be processed using a steam injector of the type disclosed by Pursuit Dynamics (such as IQF products and long pasta) can be readily processed using the system disclosed herein The invention also contemplates that a steam/air mixture may be used in place of pure steam. The use other heated fluids for heating food products is also intended to fall within the scope of the invention.

As illustrated in the drawings, the slot formed when the valve head 13 is fully forward annular. However tt falls within the scope of the invention for the slot to be part annular or for there to be a puralfty of part annular slots, or for the slot to have other shapes depending on the cross-sectional shape of the body Although the injector body illustrated in the drawings is barrel shaped, ie tapering at both its forward and rearward ends, the rearward end part of the body may instead be of the same diameter throughout its length, so that the body is generally bullet shaped Although the lip is shown in the drawings to curve continuously in the rearwards direction, it faiswithfr the scope of the invenon for the Up to be stepped or otherwise shaped n ci vvay ci IL? ciL,I 1RV II 1C U ICLL.

Claims

1 A method of processing a flowable food product within a cooking vessel, comprising injecting a heated fluid into the vessel by means of an injector including a body provided with an internal chamber to which the fluid is supplied, the fluid escaping from the chamber by way of an outlet in the form of a slot so as to heat the food product, the external surface of the nector body in the region of the slot being so shaped that the fluid leaving the slot +ri +ki+ , i,41r. *ir,rl,-Ir,sl,t.f,rspi r +ke, f,,er4 rrr,d, .r4 ht, ,Ir+, ,t çII I,I LJ 1.1 IIL..)UI Iç1%. C4J I JI �)! I�JL�, �tI �..L1ICLI%.JI �)I LI 1V.J!..J..J p.11 �)�)I.1LL IJ VII L�A fI. -.1 R) U; tne OdIIUd tiict.

2. A method as claimed in claim 1, wherein the slot is annular or part-annular and is defined between a valve head and the injector body, the valve being arranged to open against spring pressure to form the slot when the fluid is admitted to said chamber, the fluid being steam.

3 An injector in or for use in a food processing vessel including a body provided with an internal chamber, means for supplying a heated fluid to the chamber.

a slot communicating with the chamber, the slot being disposed at a forward end of the body and being bounded on its radially outer side by a lip which is extended towards the rear of the body and diverges from the axis of the slot, such that fluid discharging from the slot gives rise to a Coanda effect.

4. An injector as claimed in claim 3, wherein the chamber has a mouth at its forward end and the slot is defined between a valve head and the surface of the injector body bounding the mouth, means being provided for biasing the valve into a closed position, the valve being arranged to open and define the slot when fluid is admitted to said chamber.

5. An injector as claimed in claim 4, wherein the injector body has forward and rearward body sections, a guide for the valve stem being retained between said sections

6. An injector as claimed in claim 4 or claim 5, wherein the valve stem carries a stop located rearwardly of the guide and a compression spring is interposed between the guide and the stop

7 An injector as claimed in claim 5, wherein the rearward body section has an opening to receive a lance.

8. A cooking vessel into which extends a lance connected to a source of steam, a steam injector mounted at the end of the lance, the steam injector including a body provided with an internal chamber having a mouth at the forward end of the body, the mouth opening to the exterior of the body, a valve having a head normally biased to close the mouth and being movable by steam admitted to the chamber to open a slot around the periphery of the valve head, the slot being bounded on the side opposite to the valve head by a convexly curved lip which is extended towards the rear of the body and dinr,-ec en-sm +h,s iw,e, r,f +hc cJrt th i-s,rt,ifs tr rsf fh Irrs hcinn, ur'h fhit II L.III LI 5.s L.I/LIsJ 5JI LIISs.JI'JL, LI L. S..sI.41 VIL5.SI'.., JI LI I. IIJS Sd.,II Ij SJL.III S.I 5S.

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serr oisunaryu irorn ire slot yves rist w L.OdR(Jd eitei 9 A method of processing flowable food product within a cooking vessel substantially as hereinbefore described with reference to the drawings.

10 A steam injector substantially as hereinbefore described with reference to and illustrated in the drawings