WO2008060218A1

WO2008060218A1 - Adjustable steam injector

Info

Publication number: WO2008060218A1
Application number: PCT/SE2007/000995
Authority: WO
Inventors: Roland Ringström
Original assignee: Tetra Laval Holdings & Finance Sa
Priority date: 2006-11-13
Filing date: 2007-11-12
Publication date: 2008-05-22
Also published as: SE0602408L; SE530567C2

Abstract

The present invention relates to an adjustable steam injector (1) of the type which has an injector housing (2) with an inlet (3) for product which is to be heated and an outlet (4) for the heated product. The injector housing (2) also has an inlet (5) for steam. The injector (1) also includes an injector body (6) displaceable in the injector housing (2) and having, in its one end, a centre pin (8). Around the centre pin (8) there are disposed concentric gaps (9, 10) for product and steam, respectively. The centre pin (8) is formed so that it has a number of grooves (12) accommodated on its circumferential surface. The grooves (12) are turned towards the one end of the centre pin (8).

Description

ADJUSTABLE STEAM INJECTOR

TECHNICAL FIELD

The present invention relates to an adjustable steam injector comprising an injector housing with an inlet for a product, an outlet for the product, as well as a steam inlet, the injector further including an injector body displaceable in the injector housing, the injector body having, in its one end, a centre pin around which are disposed concentric gaps for steam and product, respectively.

BACKGROUND ART

As regards the heat treatment of liquid or pumpable foods, use may be made of steam in order, in a rapid and efficient manner, to heat the food product. One of the methods employed for introducing steam directly into the product is to use an injector. Depending upon the temperature to which it is desired to heat the product, it is possible to obtain a pasteurised or an aseptic product, or alternatively a product having an extended shelf-life in cold storage. The commonest practice is to heat the product which, for example, may be dairy produce, juices, viscous liquid food products or the like, to a temperature at which there is obtained a total extermination of harmful microorganisms. This affords a food product which keeps stable on storage at room temperature. No unbroken refrigerated chain for storage is needed, which may be an advantage above all in third world countries.

Direct heating of the product by introducing steam into the product realises a rapid and efficient heating. This rapid method entails that it is possible to reduce the treatment time, which in total gives a reduced thermal effect on the product, and a product will be obtained which maintains a high standard of quality, above all in terms of flavour.

There are available on the market a large number of injectors which all display similar construction, with an inlet for the product to be treated and an outlet for the ready-treated product. The injector further has an inlet for steam under high pressure which, through various arrangements involving gaps or ducts, is caused to converge with the product and warm it to the desired temperature. Depending upon the design and construction of the injector, with gaps or ducts, it may be suitable for products of different viscosities.

Swedish Patent Specification SE 367 121 discloses a so-called annular gap injector, where concentric gaps for steam and product are disposed about a centre pin. Annular gap injectors are known for their operational reliability since fouling of the product is not a serious problem. On the other hand, as regards viscous products, the annular gap injectors may give a poorer admixture of steam in the product, since there will be a stratification of steam and product in the injector outlet.

An injector for viscous products is described in Swedish Patent Specification SE 517 823. This injector displays an inner product pipe surrounded by a thick- walled pipe with a large number of ducts through which steam is fed to the product. However, this injector has proved to be less suitable for products which are particularly prone to fouling, such as ice-cream mix, high fat content cream, puddings, children's food or the like.

OBJECTS OF THE INVENTION

One object of the present invention is to realise an injector whose design and construction enjoys the advantages of the annular gap injector as regards fouling, but which results in an improved mixing of product and steam, in particular for viscous products.

SOLUTION

This and other objects have been attained according to the present invention in that the steam injector of the type described by way of introduction has been given the characterising feature that the centre pin has a number of grooves accommodated in its circumferential surface, the grooves being rotated towards the one end of the centre pin.

Preferred embodiments of the present invention have further been given the characterising features as set forth in the appended subclaims. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

One preferred embodiment of the present invention will now be described in greater detail hereinbelow, with reference to the accompanying Drawings. In the accompanying Drawings: Fig. 1 shows, partly in section, a side elevation of an injector according to the present invention;

Fig. 2 shows a part of Fig. 1 with two different adjustment positions, shown in magnification;

Fig. 3 shows a cross section of a groove; Fig. 4 shows a side elevation of the centre pin with the angle of rotation of the grooves; and

Fig. 5 shows a top plan view of the centre pin with the distribution angle of the grooves.

The Drawings show only those parts essential to an understanding of the present invention, and the positioning of the injector in a heat treatment plant, which is well-known to a person skilled in the art, has been omitted.

DESCRIPTION OF PREFERRED EMBODIMENT

Fig. 1 shows a steam injector 1 according to the present invention. The steam injector 1 comprises a closed injector housing 2 of substantially tubular appearance.

The injector housing 2 displays an inlet 3 for a product which is to be heat treated in the injector 1, as well as an outlet 4 for the heat treated product. The injector housing 2 also has an inlet 5 for steam. The injector housing 2 is suitably manufactured from stainless steel so that it is suitable for use together with foods and so that it is easy to wash in an efficient manner.

Inside the injector housing 2, there is disposed an injector body 6 which is displaceable in the longitudinal direction of the injector housing 2. In the one end 7 of the injector body 6, there is disposed some form of regulator device (not shown).

The regulator device may be manual or automatic and, by displacing the injector body 6, it is thus possible to adjust the capacity of the injector 1.

At the other end of the injector body 6, there is placed a centre pin 8. The centre pin 8 and the injector housing 2 are designed so that concentric gaps are formed around the centre pin 8, of which at least one gap 9 is intended for product and at least one gap 10 is intended for steam. As a result of the adjustability of the injector body 6, it is possible to regulate the gap 9 for the product flow, as shown in Fig. 2A and 2B. Both the centre pin 8 and the injector body 6 are suitably manufactured from stainless steel, so that they are suitable for use with foods and so that they are easy to wash in an efficient manner.

The centre pin 8 is, according to the invention, formed so that the first part 11 most proximal the injector body 2 is conical in such a manner that the diameter dimension of the centre pin 8 increases in relation to the diameter dimension of the injector body 6. Moreover, on this first part 11 of the centre pin a number of grooves 12 start which are milled in the circumferential surface of the centre pin 8.

The second part 13 of the centre pin 8 is straight, and on this part 13 the grooves 12 continue, partly as straight grooves, i.e. they are axially directed. On the other hand, the grooves 12 begin to turn on this part 13. The grooves 12 are turned through 30-40° and preferably 35° in relation to the longitudinal direction of the injector body 2 and the centre pin 8. This turning is shown in Fig.4 as the angle a.

The third part 14 of the centre pin 8 is once again conical with reducing diameter from the diameter of the straight, second part 13. The grooves 12 continue with the same turn throughout the entire circumferential surface of the third part 14. The grooves 12 are, in the preferred embodiment, between 5 and 30 in number, preferably 20 in number, uniformly distributed over the centre pin 8. The number of grooves 12 depends upon capacity and the width of the grooves 12. The preferred number of grooves 12 gives a distribution angle of 18°, which is shown in

Fig. 5 by means of the angle β. The number of grooves 12 may be varied and may be more or fewer than 20 in number. Another number of grooves 12 than in the preferred embodiment would naturally give a different distribution angle.

The grooves 12 have a width of 0.5-5 mm and a depth of 0.8-3.5 mm. The grooves preferably display a square, or alternatively rectangular cross section, but other types of cross section may also be employed. In the preferred embodiment, the grooves 12 have a square cross section with a width and depth of 3.5 mm. In the one end of the centre pin 8, there is disposed a guide cone 15. The guide cone 15 is placed in the outlet 4 for the heat-treated product. The purpose of the guide cone 15 is to control the mixing of product and steam out through the outlet 4. The product which enters into the injector 1 through the product inlet 3 may be a relatively viscous product, such as ice-cream mix, high fat content cream, puddings, soups, children's food or the like. The injector 1 may naturally also be employed for less viscous products.

The product which passes in through the inlet 3, into the injector housing 2, will, when it passes the first part 11 of the centre pin 8, be throttled in its flow which will assist in urging the product into the grooves 12 which start on this first part 11. The product then follows the centre pin 8 and the gap 9. As a result of the formation of the centre pin 8 and the turning of the grooves 12, an acceleration of the product will be obtained at the same time as the product is more formed as jets, rather than as a concentric column which is the case in conventional annular gap injectors.

The product jets converge with the steam which enters via the inlet 6 and then passes the gap 10. Given that the viscous product is finely divided into jets, an improved mixing will be obtained of product and steam which departs from the injector 1 through the outlet 4. With a centre pin 8 formed according to the present invention, stratification of product and steam will be avoided which could otherwise occur when use is made of a conventional annular gap injector for viscous products. The grooves 12 and their design also afford advantages as regards washing of the injector 1, since the washing liquid will be at a higher speed and be better distributed when it passes the centre pin 8. As a result of the efficient mixing of product and steam, there will be obtained a uniform and efficient heating of the product to the desired temperature. Since annular gap injectors do not give rise to serious fouling of product, there will at the same time be obtained long operational time, in particular for products showing a ready tendency to fouling, such as dairy produce of high viscosity or similar products.

As will have been apparent from the foregoing description, the present invention realises an adjustable steam injector which displays the advantages of conventional annular gap injectors as far as fouling is concerned, which thus affords long operational times. At the same time, the design of the injector gives an efficient mixing of product and steam so that there will be obtained a reliable and uniform heating of the product in the injector. The heating will be well defined and there will be obtained the desired bacteriological extermination.

Claims

WHAT IS CLAIMED IS:

1. An adjustable steam injector (1) comprising an injector housing (2) with an inlet (3) for a product, an outlet (4) for the product, as well as a steam inlet (5), the injector (1) further including an injector body (6) displaceable in the injector housing (2), said injector body (6) having, in its one end, a centre pin (8) around which are disposed concentric gaps (9, 10) for product and steam, respectively, characterised in that the centre pin (8) has a number of grooves (12) accommodated in its circumferential surface, the grooves (12) being turned towards the one end of the centre pin (8).

2. The adjustable steam injector as claimed in Claim 1, characterised in that the grooves (12) are between 5 and 30 in number.

3. The adjustable steam injector as claimed in Claim 2, characterised in that the grooves (12) are 20 in number.

4. The adjustable steam injector as claimed in Claim 1, characterised in that the centre pin (8) consists of three parts (11, 13, 14) of which the first part (11) is conical, the second part (13) is straight and the third part (14) is conical.

5. The adjustable steam injector as claimed in Claim 4, characterised in that the grooves (12) begin as axial grooves (12) on the first part (11), on the second part (13) the grooves (12) are first axial thereafter turned and, on the third part (14) the grooves (12) continue with the same turning throughout the entire third part (14).

6. The adjustable steam injector as claimed in any of the preceding Claims, characterised in that the grooves (12) have a width of 0.5-5 mm and a depth of 0.8-3.5 mm.

7. The adjustable steam injector as claimed in Claim 6, characterised in that the grooves (12) have a square cross section with a width and a depth of 3.5 mm.