RU2717031C1 - Turbulent mixer-reactor - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: turbulent mixer-reactor for reagent treatment of process flows is intended for formation of stable non-uniform systems of emulsions type and performance of mass-exchange and / or chemical processes and can be used in oil refining and chemical industry. Turbulent mixer-reactor for reagent treatment of process flows includes housing with alternating zones of turbulization of mixture of process flow and insoluble reagent, branch pipe for input of initial process flow, reagent feed branch pipe, treated process flow outlet branch pipe, in alternating turbulization zones of mixture successively use confuser, cylindrical and diffuser elements, wherein number of alternating turbulization zones of mixture N is calculated by equation, reagent feed branch pipe is connected to reagent injection nozzle in confuser element of first mixture turbulence zone, which provides spraying of reagent in form of hollow cone, wherein angle of cone α is equal to or greater than value (180-β), where β is confuser element cone angle.

EFFECT: formation of stable non-uniform system of emulsion type and achievement of required depth of conversion of chemical process.

3 cl, 3 dwg

Description

A turbulent mixer-reactor for the reagent processing of process streams is designed to form stable heterogeneous systems such as emulsions and to conduct mass transfer and / or chemical processes and can be used in the oil refining and chemical industries.

A common stage of chemical-technological processes - the mixing of technological flows - is most difficult to implement in the case of mutually insoluble liquids, for example, petroleum products and alkali to remove sulfur-containing impurities or oil and water to remove inorganic salts. The peculiarity of the processes of mixing process streams with a relatively small number of reagents is that the flowing mass transfer and / or chemical processes should be realized precisely in intensely mixed interacting streams, since during further transportation of the obtained two-phase mixtures through pipelines, they are inevitably separated into phases. The latter leads to a decrease in the interface and, consequently, to a decrease in the rate of the mass transfer and / or chemical process realized in the mixture until its almost complete cessation.

A known mixer containing a pressure and mixing chamber, representing a hollow cylinder, equipped with a discharge pipe of the working agent (water) and a pipe of the component to be mixed (oil), the mixing chamber is made at the outlet in the form of a stilling chamber, while inside the cylinder on the pipe of the component to be mixed and discharge swirling tubes are installed on the working agent’s nozzle for swirling oil and water flows moving towards each other, and the stilling chamber is a set of plates installed cited in the tube at an angle of 45 degrees (patent for invention RU 2189851 C2, IPC B01F 3/04, filed March 23, 2000, published September 27, 2002). The disadvantages of the invention are:

- a constant diameter of the mixer, which does not allow changing the hydrodynamic mode of operation of the device, since due to the input of the working agent (water), the Reynolds number changes slightly and remains constant along the flow;

- the presence of swirls that adversely affect the operation of the mixer, since in the field of centrifugal forces arising from the rotational movement of flows, phase separation will occur, while the dispersible aqueous phase will be discarded to the periphery of the mixer, forming a film of water instead of mixing it with oil;

- the presence of a soothing chamber that reduces the degree of turbulence of the flows and intensifies the deposition of droplets of dispersed water, which impairs mixing.

A turbulent reactor for mixing heterogeneous mixtures is known, including a cylindrical body with nozzles for supplying reagents and alternating coaxial inserts arranged in it in the form of confuser-diffuser elements installed with a step H = 5.6 · D, where H is the installation step of the confuser-diffuser elements, m, D is the diameter of the reactor, m, and the confuser is made subject to the condition l = 0.5 · d, where l is the length of the confuser, m, d is the diameter of the narrowed part of the confuser and diffuser, m (patent for the invention RU 2298430 C1 , IPC B01F 5/00, claimed 30.08.2 005, published May 10, 2007). The disadvantages of the invention are:

- nozzles for supplying reagents, mating with the body in the contact zone of the confuser and diffuser elements without additional impact on the reagent, which prevents the latter from dispersing with the formation of an independent stream in the absence of solubility of the reagent in the main stream entering the center of the reactor;

- an extended diffuser, the length of which is more than five times the length of the confuser part, while in the diffuser there is a decrease in speed and expansion of the flow, leading to a decrease in the intensity of its turbulization.

There is also known a method of desalting gas condensate, which is carried out in a turbulent apparatus of a diffuser-confuser structure, the diffuser-confuser section is a combination of a diffuser, a linear section and a confuser, the apparatus can have several sections, while the prepared gas condensate enters the inlet channel of the first section of the tubular turbulent apparatus a diffuser-confuser structure, and washing water is coaxially introduced into it through a perforated pipe with a closed end end (patent for the invention Ie RU 2473667 C1, IPC C10G 31/08, C10G 33/04, declared December 7, 2011, published January 27, 2013). The disadvantages of the invention are:

- a consistent combination in the confuser-diffuser section of the diffuser, the linear section and the confuser, leading to the lowest flow rates and the least degree of turbulization in the longest linear section of the largest diameter, which affects the quality of mixing;

- the introduction of washing water through a perforated pipe with a closed end end, leading to the supply of an aqueous dispersed phase only to the periphery of the inlet channel without entering the central part of the gas condensate stream due to the blocked end of the pipe.

Closest to the claimed invention is a turbulent mixing reactor, including a cylindrical body with nozzles for supplying reagents, divided along the length of alternating coaxial confuser-diffuser elements, confuser-diffuser elements are made in each section perpendicular to the axis of their material symmetry, in the form of compressed ovals, length the perimeter of the ovals is equal to the perimeter of the cross section of the cylindrical body (patent for invention RU 2626205 C1, IPC B01F 5/00, filed July 4, 2016, published July 24, 2017). The disadvantages of the invention are:

- the complexity of the design of the mixing reactor, requiring pairing confuser-diffuser elements of the oval shape with a cylindrical body;

- pairing the nozzles for supplying reagents with the housing in the contact zone of the confuser and diffuser elements without additional impact on the reagent, which prevents the latter from dispersing with the formation of an independent stream in the absence of solubility in the main stream entering the center of the reactor;

- the location of the zone of least turbulization in a cylindrical section of the housing located between the diffuser and confuser elements, which affects the quality of mixing.

When creating the invention, the task was to develop a turbulent mixer-reactor for the reagent processing of process streams, ensuring the formation of a stable heterogeneous system such as an emulsion and achieving the necessary conversion depth of the chemical process.

The problem is solved due to the fact that in a turbulent mixer-reactor for reagent processing of process streams, which includes a housing with alternating turbulization zones of a mixture of a process stream and an insoluble reagent in it, an inlet of an input of an initial process stream, an inlet of a reagent inlet, an outlet pipe of a processed process stream, in alternating turbulization zones of the mixture, confuser, cylindrical and diffuser elements are sequentially used, while the number of alternating turbo zones lization mixture N is calculated by the equation:

where K is the constant of the reaction rate of the reagent with the component of the process stream, h ^-1 ;

V is the flow rate of the process stream, m ³ / h;

ν - reagent consumption, m ³ / h;

C ₀ is the initial concentration of the component of the process stream that reacts with the reagent,%;

C is the final concentration of the component of the process stream that reacts with the reagent,%;

D is the diameter of the base of the cone of the confuser and diffuser elements, m;

d is the diameter of the cylindrical element, m;

h ₁ , h ₂ and h ₃ - the length of the confuser, cylindrical and diffuser elements, respectively, m;

the reagent inlet pipe is connected to the reagent inlet nozzle in the confuser element of the first turbulization zone of the mixture, which provides spraying of the reagent in the form of a hollow cone, and the cone angle α is equal to or greater than (180-β), where β is the cone angle of the confuser element.

In the case where the turbulization zone of the mixture of the process stream and the insoluble reagent in it consists sequentially of confuser, cylindrical and diffuser elements, ceteris paribus, the most intense turbulization of the flow is achieved compared to a cylindrical zone or a zone consisting in series of diffuser, cylindrical and confuser elements. As follows from the results of calculations of the turbulization zone of the mixture with a narrowing diameter of the confuser equal to half the diameter of the expansion of the diffuser and cylinder, the relative intensity of turbulization, considered as the ratio of the Reynolds number in individual elements of the turbulization zone of the mixture (Re _EL ) to the Reynolds number for a cylindrical mixer (Re _C ) , for the claimed invention is more uniform and high. In FIG. 1 shows the dependences of Re _EL / Re _C on the length of the turbulization zone L for a cylindrical mixer (a), the mixer according to the prototype (b) and the claimed invention (c). The combination in the turbulent mixer-reactor of adjacent diffuser and confuser elements of adjacent turbulence zones of the mixture leads to a decrease in the flow velocity in this section compared to the previous and subsequent cylindrical elements and to the transition of part of the kinetic energy of the flow to potential with a sharp increase in pressure, creating a local hydraulic shock within a split second with the crushing of droplets of the dispersed phase, which increases the interface and intensifies mass transfer and / or chemical e processes at the subsequent linear portion.

The developed equation allows you to calculate the number of alternating zones of turbulization of the mixture to ensure a given conversion of the chemical process between the process stream and the reagent, calculated as KONB = (C ₀ -C) / C ₀ , or a decrease in the initial concentration C _{0 of the} component of the process stream that reacts with the reagent to its final concentration C.

The use of a reagent injection nozzle spraying it in the form of a hollow cone ensures that the reagent is injected under pressure into the continuous medium of the process stream in the form of a thin conical film flying out at a right angle with respect to local streams of the continuous medium due to the cone angle α being equal to ( 180-β), or towards the flow of local jets of a continuous medium, if the cone angle α is greater than the value (180-β), due to which the film is crushed into small droplets. If the cone angle α is smaller than (180-β), then the direction of motion of the conical reagent film substantially coincides with the direction of motion of the local jets of the continuous medium, which leads to a weakening of the impact of the film on the continuous medium and the enlargement of the formed droplets of the dispersed phase.

It is advisable in some cases, in particular, during the chemical interaction of the process stream with the reagent, to place the nozzle for introducing the reagent in the confuser elements of several or all zones of turbulization of the mixture, since during the course of the chemical process as the reagent is converted, the speed of the chemical process decreases. Additional input of the reagent into several specific turbulization zones or into each of them will increase the rate of chemical interaction and will reduce the size of the apparatus.

It is also advisable that the reagent injection nozzle provides a spray of the reagent in the form of a hollow cone with a base diameter greater than the diameter of the cylindrical element d and less than the diameter of the base of the cone of the confuser and diffuser elements D, since when the base diameter is less than d, the reagent is introduced only into the axial region of the apparatus, and when the diameter of the base is greater than D part of the conical reagent film withdrawn from the nozzle is converted into a cylindrical film near the wall of the confuser element, which in both cases leads to lower the homogeneity of the formed emulsion.

In figures 2 and 3 presents the basic structure of the first turbulization zone of the mixture of turbulent mixer-reactor and turbulent mixer-reactor as a whole, respectively, using the following notation:

I is the initial process stream;

II - reagent;

III - processed process stream.

1 - pipe input of the original process stream;

2 - case;

3 - confuser element;

4 - a cylindrical element;

5 - diffuser element;

6 - pipe input reagent;

7 - nozzle input reagent;

8 - zone of turbulization of the mixture;

9 - outlet pipe of the processed process stream.

The initial process stream I, for example, gasoline, which must be cleaned of sulfur compounds, enters the body 2 through the input pipe of the source process stream 1, which consists of several alternating zones of turbulization of the mixture 8 (in Fig. 3, case 2 includes six zones of turbulization of the mixture 8) . Each turbulization zone of mixture 8 of length L of the _ZTS consistently consists of a confuser element 3, a cylindrical element 4 and a diffuser element 5, with lengths L _K , L _C and L _D , respectively (Fig. 2).

At the entrance to the first turbulization zone of the mixture (Fig. 2), the initial process stream I is mixed with a stream of reagent II, for example, an aqueous solution of sodium hydroxide introduced into the housing 2 through the nozzle of the input of the reagent 6 using the nozzle of the input of reagent 7. The aqueous solution of sodium hydroxide under the pressure is ejected from the injection nozzle of the reagent 7 in the form of a conical film, which striking against the turbulized local jets of the continuous medium of the initial process stream I is crushed into separate jets and drops forming a mixture with the initial technological by stream I, forming a constantly mixing emulsion of gasoline and an aqueous solution of alkali with a developed interface. In this case, sodium hydroxide reacts with hydrogen sulfide and mercaptans:

2NaOH + H ₂ S → Na ₂ S + 2H ₂ O,

NaOH + H ₂ S → NaHS + H ₂ O,

NaOH + RSH → RSNa + H ₂ O,

to obtain water-soluble reaction products, passing into an aqueous solution of alkali.

The reaction mixture passes sequentially through a series of turbulization zones of mixture 8 with the highest degree of turbulence of the emulsion, which prevents its separation into continuous gasoline and water phases in cylindrical elements 4, which together constitute more than 90% of the total length of the turbulent mixer-reactor, and in the sections formed by the conjugate diffuser elements 5 and confuser elements 3 of the adjacent turbulization zones of the mixture 8 due to hydroblows during the conversion of part of the kinetic energy of the flow into potential additional Noe fragmentation reagent droplets.

In the present use of a turbulent mixer-reactor, an additional reagent is provided to accelerate the reaction into the fifth turbulent zone of mixture 8 along the initial process stream (Fig. 3). The reaction mixture that has reacted to the required depth of gasoline purification in the form of a processed process stream III is discharged from the housing 1 through the outlet pipe of the processed process stream 9.

Thus, the claimed invention solves the problem of developing a turbulent mixer-reactor for the reagent processing of process streams, ensuring the formation of a stable heterogeneous system such as an emulsion and achieving the necessary conversion depth of the chemical process.

Claims (13)

1. A turbulent mixer-reactor for the reagent processing of process streams, comprising a housing with alternating turbulization zones of the mixture of the process stream and the insoluble reagent in it, a pipe for introducing an initial process stream, a pipe for introducing a reagent, a pipe for outputting a processed process stream, characterized in that in alternating zones turbulization mixture consistently use confuser, cylindrical and diffuser elements, while the number of alternating zones of turbulization of the mixture N calculated yut by the equation:

where K is the constant of the reaction rate of the reagent with the component of the process stream, h ^-1 ; V is the flow rate of the process stream, m ³ / h; ν - reagent consumption, m ³ / h; C ₀ is the initial concentration of the component of the process stream that reacts with the reagent,%; C is the final concentration of the component of the process stream that reacts with the reagent,%; D is the diameter of the base of the cone of the confuser and diffuser elements, m; d is the diameter of the cylindrical element, m; h ₁ , h ₂ and h ₃ - the length of the confuser, cylindrical and diffuser elements, respectively, m; the reagent inlet pipe is connected to the reagent inlet nozzle in the confuser element of the first turbulization zone of the mixture, which provides spraying of the reagent in the form of a hollow cone, and the cone angle α is equal to or greater than (180-β), where β is the cone angle of the confuser element. 2. The mixer-reactor according to claim 1, characterized in that the nozzle for introducing the reagent is placed in the confuser elements of several or all zones of turbulization of the mixture. 3. The mixer-reactor according to claim 1, characterized in that the reagent injection nozzle provides a spray of the reagent in the form of a hollow cone with a base diameter greater than the diameter of the cylindrical element d and less than the diameter of the base of the cone of the confuser and diffuser elements D.

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