Technical Field

[0001 ] The present invention concerns the use of a static mixer for intensification of mixing and homogenization of the processed medium in flat panel reactors.

[0002] During the scaling up of flat panel reactors, it is necessary to ensure the homogenization of the processed medium. For example, in the case of irradiated photobioreactors, as the thickness of the culture medium layer increases, there may be insufficient illumination of the microalgal cells. In larger volumes of culture medium, thermal gradients and inefficient use of nutrients can occur. A common problem is also the sedimentation of the produced microalgal cells, which are trapped on the transparent surfaces of the flat panel photobioreactor and thus prevent the irradiation of the culture medium layer. These parameters are influenced by the hydrodynamics of the culture medium. Therefore, it is important to ensure sufficient mixing of the culture medium so the all microalgal cells can be irradiated and at the same time the mass transfer is intensified. By intensifying the mixing in the area of the transparent plates, the formation or disruption of the stability of the formed layer of trapped microalgal cells can also be eliminated. ikground Art

[0003] Flat panel reactors are one of the basic representatives of closed systems, which are often used in the chemical or pharmaceutical industry. A typical example of the use of industrial flat panel reactors is in biotechnologies, for example in the production of microalgal biomass, which can be further used in the food, pharmaceutical or cosmetic industries. Flat panel photobioreactors are also used in wastewater treatment systems, or in biorefineries involving the production of biofuels and higher value-added products.

[0004] The principle of the flat panel photobioreactor is to enable sufficient irradiation of microalgae cells and to ensure the supply of nutrients that microalgae need for their growth. Huang J. et al. in his work Novel Flat-plate Photobioreactors for Microalgae Cultivation with Special Mixers to Promote Mixing Along the Light Gradient, Bioresource Technology, 2014, describes the importance of ensuring sufficient mixing of the culture medium in systems for industrial application.

[0005] More intensive mixing and prolongation of the residence time in the irradiated area of the photobioreactor was achieved here by installing baffles which, by their geometry, extend the flow path of the microalgal cells between the inlet and outlet of the flat panel photobioreactor chamber. Degen J. et al. in A Novel Airlift Photobioreactor with Baffles for Improved Light Utilization Through the Flashing Light Effect, Journal of Biotechnology, 2001 , describes the effect of intensification of agitation on biomass production from microalgae. By installing baffles, which are attached in parallel to the transparent surfaces of the flat panel photobioreactor, the culture medium is mixed by the individual baffles. Wang L. et al. in A Novel Flat Plate Algal Bioreactor with Horizontal Baffles: Structural Optimization and Cultivation Performance, Bioresource Technology, 2014, optimized the design of baffles in the transparent chamber of a flat panel photobioreactor to increase biomass production from microalgae.

[0006] Published designs divide the irradiated area of the flat panel photobioreactor into individual chambers, which locally mix the processed culture medium and prolong the residence time.

[0007] Existing designs are relatively expensive and their construction is complex. nmary of the invention:

[0008] Difficulties and problems associated with scaling up of flat panel reactor are eliminated by installing a static mixer in the reactor chamber according to this invention. The static mixer comprises at least one segment formed by two blades located perpendicular to the transparent surface of the flat panel reactor. The blades are rotated at an angle of 30 to 150° to each other. Another blade in segment is inclined at an angle of 30 to 60° to the transparent surface of the flat panel reactor.

[0009] The segments are installed in at least one row. [0010] In a preferred configuration, the static mixer comprises at least two rows of segments in a parallel arrangement and/or comprises at least two rows of segments which are arranged in an inclined configuration at an angle of 5 to 60° to each other.

[001 1 ] The aim of the construction of the static mixer is to intensify the mixing and to homogenize the flow of the processed medium. The geometry of the static mixer is designed to divide the inlet stream of medium into several individual streams that will mix with each other. The geometry is further adapted to create the wake behind the blades of the static mixer. The creation of wakes causes the medium to swirl. Moreover, formed wakes can interact with each other and further intensify the mixing of processed medium.

[0012] The design of the static mixer allows the intensification of mixing in the entire cross-section of the flat panel reactor chamber. At the same time, the static mixer distributes the flow of process medium over the entire cross-section of the chamber, which results in uniform residence times of the process medium in the reactor. The installation of a static mixer in the flat panel reactor chamber has shown a reduction in the time required to homogenize the processed medium.

[0013] By installing the segments of the static mixers, the flowing medium is homogenized in the entire chamber of the flat panel reactor. With the help of the designed geometry of the static mixer, the processed medium is more intensively mixed.

[0014] Local increase of the flow velocity occurs due to the inclined geometry of the blades of the static mixer. Moreover, the inlet stream of processed medium is divided into individual streams which are mixed with each other in the entire volume of processed medium. The blades of the static mixer allow the formation of wakes in the area behind the blades, which causes the swirling of processed medium and further intensify the mixing conditions.

Brief of the [0015] The invention itself will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.

Fig. 1 a shows a front view, Fig. 1 b a plan view, and Fig. 1 c a side view of a segment of a static mixer.

Fig. 2 is a perspective view of a segment of a static mixer.

Fig. 3a shows the flow streamlines behind the blades perpendicular to the wall of the flat panel reactor. Fig. 3b shows the flow streamlines behind the blades inclined at an angle to the flat panel reactor wall.

Fig. 4a shows a plan view of a static mixer formed by segments arranged in a row which is installed in a flat panel reactor chamber.

Fig. 4b shows a parallel configuration of rows of segments in partial section in a plan view, and Fig. 4c show the rows of segments in partial section in a perspective view.

Fig. 5a and Fig. 5b show the location of rows of static mixers in mutually rotated configurations in a plan view.

Fig. 6a shows a comparison of the streamlines in the empty chamber of the flat panel reactor and in the chamber with one set of static mixers. Fig. 6b shows the distribution of the flow velocity in an empty chamber and in a chamber with one set of static mixers installed.

Detailed description of the preferred embodiments:

[0016] A static mixer in a flat panel reactor chamber according to the present invention comprises at least one segment formed by two blades 1 located perpendicular to the transparent wall of the flat panel reactor, which are rotated at an angle of 90° to each other, another blade 2 inclined at an angle of 45° to the transparent wall of the flat panel reactor.

[0017] A pair of blades 1 perpendicular to the wall of the flat panel reactor direct the flow of the processed medium to the side of the flat panel reactor chamber. By changing the flow direction, the flow of the processed medium is merged with the flow, which is directed by another blades 2 inclined at an angle to the wall of the flat panel reactor.

[0018] By reducing the flow cross-section between the blades 1, and the flow cross-section between the blades 2 and the wall of the flat panel reactor, a local increase in the flow rate occurs. Behind the blades 1 and the blades 2 of the static mixer, the formation of wake occurs, which results in the formation of vortices and the associated intensification of mixing.

[0019] Fig. 3a shows the flow streamlines behind the blades 1 perpendicular to the wall of the flat panel reactor. Fig. 3b shows the flow streamlines behind the blades 2 inclined at an angle to the wall of the flat panel reactor.

[0020] In another embodiment, the individual segments are arranged into rows 3, which are subsequently installed in the flat panel reactor chamber according to Fig. 4a. The parallel arrangement 4 of rows 3 of segments of the static mixer is shown in Fig. 4b in partial section in plan view, and in Fig. 4c in partial section in perspective view. According to the requirements for mixing intensity and flow homogenization, it is possible to choose the mutual distance of parallel installed rows 3 of static mixers or their mutual inclination. According to the configuration of inflow of the processed medium into the chamber of the flat panel reactor, it is possible to install rows 3 of static mixers in mutually inclined configurations 5 according to plan view shown in Fig. 5a and Fig. 5b.

[0021 ] Fig. 6a shows a comparison of the streamlines in the empty chamber 6 of the flat panel reactor and in the chamber 6 with one row 3 of static mixers. In the empty chamber 6, a circulation loop is formed, which results in an uneven retention time of the processed medium in the chamber 6 of the flat panel reactor and the formation of dead zones. In the chamber 6 with one row 3 of static mixers installed, the flow is stable and completely homogenized in the entire cross-section of the reactor chamber 6. Fig. 6b shows the distribution of the flow velocity in the empty chamber 6 and in the chamber 6 with one row 3 of installed static mixer. From the comparison, it is possible to observe a more homogenous distribution of the flow velocity in the chamber 6 with one row 3 of static mixer installed. Industrial Applicability

[0022] The static mixer can be usable especially for the intensification of mixing and homogenization of the processed medium in flat panel reactors.