Agitating – Having specified feed means – By suction
Reexamination Certificate
2000-05-31
2001-10-09
Soohoo, Tony G. (Department: 1723)
Agitating
Having specified feed means
By suction
C137S003000, C366S144000, C366S172100, C366S177100
Reexamination Certificate
active
06299343
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to methods of heating and/or homogenizing of liquid products in a steam-liquid injector. By liquid products (hereinafter: products) are meant liquids with different degrees of viscosity, with or without solid particles (solid phase) dispersed in them. By a steam-liquid injector is meant an injector which uses steam as a process medium and liquid as injected medium.
The prior art methods of heating and/or homogenizing of products in a steam-liquid injector include the following steps:
feeding steam and a product into a mixing chamber—through a steam nozzle and a product nozzle accordingly;
forming in the mixing chamber a two-phase steam-liquid flow by mixing the product with steam;
compressing the two-phase steam-liquid flow and condensing steam in the product.
Examples of the use of this method and devices based thereon can be found in the following patents:
[1] WO 89/10184, also published as EP 0399041, describes an emulsifier based on a passive steam-liquid injector;
[2] SU 1472052 describes a method of liquid foodstuff heating in a steam-liquid injector;
[3] SU 1281761 describes a water-heating steam-liquid injector.
[4] SU 1507299 describes a pasteurization method for a liquid whole milk substitute in a passive supersonic steam-liquid injector,
[5] U.S. Pat. No. 5,205,648 and [6] U.S. Pat. No. 5,275,486 <<Method and Device for Acting upon Fluids by Means of a Shock Wave>> describe, as an instance of application, heating and homogenizing of liquid foodstuffs in a steam-liquid injector, wherein product and steam are fed to the mixing chamber at a subsonic speed, creating a two-phase steam-liquid mixture; in the process the mixture is first sped up to the sonic and then to a supersonic speed and, due to a shock wave, transformed into a single-phase liquid flow traveling at a subsonic speed.
[7] U.S. Pat. No. 5,544,961 <<Two-Phase Supersonic Flow System>> describes, as an instance of application, heating and homogenizing of liquid foodstuffs in a steam-liquid injector, with product fed to the mixing chamber at a subsonic speed and steam fed at a supersonic speed, creating a two-phase steam-liquid mixture traveling at a supersonic speed; in the process the two-phase steam-liquid flow, due to a shock wave, is transformed into a single-phase liquid flow traveling at a subsonic speed.
[7] U.S. Pat. No. 5,544,961 <<Two-Phase Supersonic Flow System>> describes, as an instance of application, heating and homogenizing of liquid foodstuffs in a steam-liquid injector, with product fed to the mixing chamber at a subsonic speed and steam fed at a supersonic speed, creating two-phase steam-liquid mixture traveling at a supersonic speed; in the process the two-phase steam-liquid flow, due to a shock wave, is transformed into a single-phase liquid flow traveling at a subsonic speed.
Some distinctive features of the method and device suggested by the above patent provide for a more stable operation of the injector, a higher shock wave and a higher degree of sterility and homogeneity of the product.
From the points of the essence of the present invention, the number of common features and the objects in view, its closest prototype is the method and device described in an article [8] under the title <<The Principle and the Use of a New Multifunction Direct Steam Technology (Ultrasonic Device) in Food and Dairy Industry>> by M. Rogenhofer, E. Hauss and V. Fissenko, published in <<Magazine for Food and Dairy Industry>> # 13/114, Mar. 25, 1993).
[8] [M. Rogenhofer, E. Hauss, V. Fisenko <<Aufbau und Wizkungsweise einer neuen multifunktionalen Uberschall-Direktdampf-Technologie (Transsonic-Gerat) fur den Milch-und-Lebensmittelbereich>>].
According to the authors of the above article, the injector described in their article was based on U.S. Pat. No. 5,205,648 [5] and U.S. Pat. No. 5,275,486 [6].
Based on testing operating conditions given in the article, it can be presumed that under some regimes (according to steam pressures forward of the injector and inside the mixing chamber) the steam was fed to the mixing chamber at a supersonic speed. In other words, in such cases the injector operated according to U.S. Pat No. 5,544,961 [7]. This enables us to consider the results according to several patents simultaneously.
The test data reported in the above article demonstrate that the required homogenizing standards have not been achieved whereas the pasteurization quality corresponds to that achieved on conventional equipment at an appropriate temperature. From FIG.
5
and information contained in the article [8], it can be seen that the stability of the injector's operation decreases sharply with the increase in the injection index, i.e. with reduction of the product's temperature difference between the inlet and the outlet of the injector. In all the above analogs and prototypes all the essential features, both of methods and devices, are related to conditions of steam feeding to the mixing chamber, proportions between the dimensions of the steam nozzle channel and the mixing chamber, and the effect of these parameters on the injector's operation. The device's longitudinal section given in FIG.
2
. in the article.[8] and description of its operation demonstrate that the product nozzle's critical section area is sufficiently large to allow a relatively low speed of product at the point where it is mixed with The steam. The fact that the device works as a passive injector suggests a low speed of product. Likewise, in other designs or design and calculation instructions for injectors no importance is attached to the flow speed in the mixing area. For instance: [9] Y.Y. Sokolov and N. M. Zinger, <<Stream Devices>>, Moscow, <<Energhia>>, 1970, pp. 234-251.
The stability of the injector's operation, especially at the moment of start and in transient condition, remains one of the main problems of the prior art injector systems.
Accordingly, they require highly skilled maintenance staff especially start up men. As a result, the injectors are perceived as unreliable and unpredictable devices which restricts their application despite their many advantages
OBJECTS AND SUMMARY OF THE INVENTION
The aim of the present invention is to improve the quality of products processed by the injector Quality attribute of foodstuffs and pharmaceutical products, for instance, are sterility, homogeneity, reduced thermal melting of proteins, conservation of vitamins, biological activity, etc. The other aims of the present invention include: increasing the stability of the injector's operation, increasing its injection index and regulating the intensity of the shock wave.
The stated aim can be achieved by the following method:
steam and liquid product are fed into the mixing chamber of the injector through a steam nozzle and a product nozzle correspondingly, in said chamber, two-phase steam-liquid flow is formed by mixing the product with steam; this flow is subjected to compression causing condensation of the steam in the product; the product is accelerated at entry to the mixing chamber to a maximum permissible speed matching processing operating conditions while not exceeding the speed at which the static pressure of the flow matches the saturation pressure at an input temperature of the product, the maximum speed, according to the liquid flow speed curve in the injector channel before steam feeding, being observed at the output cross-sectional area of the product nozzle.
The above operation sequence relates to the general case. The preferred options of embodiment of the suggested method are as follows:
steam is fed to the mixing chamber at the sonic or a supersonic speed;
steam is fed to the mixing chamber with temperature equal to or lower than final product heating temper
Blank Rome Comisky & McCauley LLP
Soohoo Tony G.
Tivon Co.
LandOfFree
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