FR2566676A1 - Continuous mixing device - Google Patents

Abstract

Devices for continuous mixing of liquid/liquid, liquid/gas and gas/gas phases enabling a liquid or gaseous substance to be distributed rapidly and uniformly in another liquid or gaseous substance in the form of a very fine dispersion. The principle of the invention lies in the introduction and distribution of the substances to be mixed with other substances by means of distribution nozzles with a solid jet, a solid cone or a hollow cone. The nozzles are housed in a chamber which is made up of two spherical spaces. The substance to which another substance is to be fed enters the lower space and moves towards the upper space through a constriction ring which separates the two spaces. The substances to be injected leave the nozzle at a speed which is much greater than that of the main stream and enter the depth of the lower space, where they are distributed into the reaction mass in the form of very fine droplets. The constriction ring produces an increase in the speed of flow of the reaction mass, and this gives rise to the formation of turbulence which further promotes the quality of mixing. The nozzle can move vertically in relation to the constriction ring; in this way it is possible to vary the constriction section between the two spaces, and this permits variable speed gradients. The most advantageous applications of the invention are in the fields of water and sewage treatment, of addition of auxiliary substances to a reaction mass and wherever mixing operations between liquids, gases and liquids, and between gases need to be performed.

Description

 The present invention relates to devices for continuous mixing of the liquid / liquid, liquid / gaseous and gaseous / gaseous phases, making it possible to rapidly and uniformly distribute a liquid or gaseous substance in another liquid or gaseous substance in the form of a very fine dispersion. .

So far there are two main lines of the mixing technique:
a - Mixing of medium viscous and solid fluid media, using mechanical agitators, the main types of which are represented by propeller agitators, with inclined blades. with pulse against the current. disc, anchor. and by turbines with various achievements.

 b - Mixing liquids and gat using static mixers incorporated in a stream of so-called liquids or gases. Their operating principle is based on the formation of individual layers by means of elements with progressive division of the total current.

 There are mixing processes, accompanied by chemical reactions which must take place within a period of 0.2 to 1 second. for example the supply of an electrolyte to a polyphase aqueous system with the aim of separating these phases by the hydrolysis of said electrolyte. At the same time. it is often necessary to face the requirement to suppress local overconcentrations or subconcentrations in reagents in a reaction mass and to avoid shear forces on the reaction products.

 With mechanical stirrers, it is not possible to obtain the envisaged goals because a) the mixing time depends largely on the speed of recirculation of the reaction mass, b) local over-concentrations or sub-concentrations of individual components are inevitable, and c) because of the high shear forces which are always exerted on the reaction products.

 As for static mixers, these are already better suited to mixing tasks. However, they have the inconvenience, due to the division of the current of the reaction mass into individual nets. to cause further distribution of the residence time, to exert - by the edges of their mixing elements - significant shear forces on the reaction products and to be subjected to the risk of clogging.

 The object of the present invention is to overcome the drawbacks of the prior art, and to propose mixing methods in which the transfers of material and energy are favored.

 The principle of the present invention is based on the introduction and distribution of a liquid or gaseous substance in another liquid or gaseous substance by means of dispensing nozzles with solid cone, solid cane or hollow cane.

The nozzles in question are housed in a sort of chamber which consists of two spheres. an upper sphere and a lower sphere. The liquid or gaseous substance to which another liquid or gaseous substance is to be fed enters the lower sphere and moves towards the upper sphere through a throttling ring which separates the two spheres. The substances to be injected leave the dispensing nozzle with a speed much greater than that of the main stream and consequently penetrate into the depth of the lower sphere where they are finely distributed in the reaction mass in the form of droplets of extremely small size The choke ring causes an increase in the flow rate of the reaction mass, which gives rise to the formation of turbulences which further promote the quality of the mixture. The dispensing nozzle is housed in the upper sphere and can move vertically relative to the choke ring. This possibility of a vertical movement of the central nozzle the flow section between the two spheres which allows variable speed gradients.

 The attached figure shows an embodiment of the said invention. The current enters the mixer by flowing from the tubing 1 and continues its path through the sphere 2 of the chamber. It then crosses the throttle ring 3 and undergoes an increase in the speed of flow here. The sphere 4 contains the dispensing nozzle 5. The reaction mass leaves the mixer by way of the tube 6.

 The details of the present invention, its advantages and characteristics, will be better understood on reading the following examples of practical application.

Example i:
Neutralization of acidic or alkaline waters.

 The water to be neutralized is brought to the mixer.

Here, the neutralizing reagent is injected into the stream of water to be neutralized. Depending on the degree of acidity or alkalinity, and consequently depending on the amount of reagent to be added, the nozzle is raised or lowered in order to obtain the optimal speed gradient for the reaction in question. The uniform and rapid distribution of the reagent through a well-defined section of the current promotes the reaction rate. This has the consequence that the distance to be traveled by the reaction mass until final neutralization is obtained is very short, which makes possible a sensitive and exact regulation of the pH without appreciable oscillations in the regulation circuit. According to the operational conditions and the parameters present. you can use a full cone, solid cone or hollow cone nozzle. If a heat of neutralization is released during the reaction, the mixer will be equipped with a cooling device, either in the form a double jacket, either in the form of cooling fins, etc.

Example 2:
Preparation of micro-emulsions for work
metals.

 In the preparation of said microemulsions, it is important to avoid the local formation of emulsions of the water in 1 oil type which can occur by a slow and unbalanced mixing. The mother solution, by its distribution in the form of very fine particles due to the atomizing effect of the nozzle of the present mixer, is immediately distributed through a well-defined section of the water stream. This phenomenon favors the final emulsion of the mother solution and increases the stability of the emulsion.

Example 3:
Mixture of fuel additives.

 To improve the quality of fuels. it is essential to add extreme pressure additives, antioxidants, etc. This addition is considerably facilitated by the use of a chaste of mixers described here.

Example 4:
Breakage of used metalworking emulsions.

 In the treatment of industrial waste water. the breaking of used emulsions is a particularly painful problem. This breaking is most often carried out using aqueous solutions of metal salts. However. to obtain an efficient breaking, it is necessary to mix these solutions with the spent emulsion in a time of less than one second in order to pocket the premature formation of hydroxides which are not effective for the destabilization of the system. Indeed, no mixing method known to date gives satisfactory results. The present invention. on the contrary, offers a valid means for this purpose. By the appropriate choice of the speed of the jet leaving the nozzle and the flow speed of the emulsion to be broken. the mixing time can be reduced to O. i second. This has the consequence of allowing the intermediate hydrolysis products to exert their destabilizing activity on the emulsifying system, which results in the separation of the aqueous and oily phases.

 Other areas of application.

 Other fields of application of the present invention, by way of example, are: the treatment of drinking water.

the addition of propane to a diesel fuel in order to improve the ignition properties, the equalization of temperatures between heat transfer oils, the mixture of liquid dyes, etc. In short.

the present invention is of economic and technical value wherever mixtures between liquids. between gases and liquids, or between different gases will be carried out.

Claims (5)

 1. Device for continuous mixing of liquid / liquid phases. liquids. carbonated. this device characterized by the distribution of a substance in another substance in a rapid and uniform manner using nozzles at and full. with solid cone. or hollow cone.  2. Mixing device according to claim 1, characterized in that the dispensing nozzles can be moved in the axial direction relative to the liquid or gaseous flow to vary the speed gradients.  3. Mixing device according to claims i and 2 characterized in that the distribution nozzles are housed in a chamber which consists of two spherical spaces, an upper space and a lower space and whose intersection lines form a ring of strangulation between the two spaces.  4. Mixing device according to claims 1, 2 and 3. characterized in that the movement of the dispensing nozzle controls the flow section between the two spherical spaces which allows variable speed gradients.  5. Mixing device according to claims 1.2. 3 and 4. characterized in that the throttle ring causes an increase in the flow rate of the reaction mass, which gives rise to the formation of turbulences which promote the quality of the mixture.