Reactor with Dynamic Sparger

Abstract

A system and method for a dynamic sparger for generating fine bubbles in a reactor, such as biological and chemical reactors. The sparger system is disposed within the reactor and includes a support plate, a plurality of annular shrouds engaging the support plate, and a sparger disposed within the annular shrouds defining a gap between an inner surface of the annular shroud and an outer surface of a corresponding sparger. Liquid flows through the gap defined between the inner surface of the annular shroud and the outer surface of the sparger. Acceleration of the liquid through the gap shears bubbles on the outer surface of the sparger, generating bubbles or fine bubbles.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 263,507, filed November 3, 2021, the entire contents of which are incorporated herein by reference.

[0002]

[0001] Embodiments described herein generally relate to systems and methods for injecting gas bubbles into liquids. In particular, the systems and methods disclosed herein generally relate to dynamic spargers for generating and injecting gas bubbles or microbubbles into liquid broths in chemical or biological reactors. Additionally, systems and methods are disclosed herein for injecting microbubbles of a gaseous carbon substrate into a bioreactor containing a liquid microbial culture that biologically ferments the carbon substrate to produce useful products, such as ethanol or other chemicals. [Background technology]

[0003] A sparger is a device that injects gas into a liquid. When gas is injected into a liquid through a sparger, gas bubbles are formed in the liquid. Conventional systems that use spargers to generate and inject gas bubbles into liquids during industrial processes are well known. To maximize the conversion of gaseous substrates injected into a liquid into useful fermentation products in a bioreactor, the sparger must increase the gas flow rate through the sparger to generate small bubbles. However, conventional sparger systems cannot achieve the required small bubble size because the sparger bubble size increases with increasing gas flow rate. Therefore, there is a need for a sparger system that can generate fine bubbles at higher gas flow rates in bioreactors and achieve high productivity. Furthermore, conventional "frit and sleeve" sparger systems, which consist of a porous ring (frit) surrounded by a sleeve through which the liquid passes, are typically external to the reactor, resulting in inefficient configurations and a large required footprint.

[0004] The sparger system disclosed herein overcomes the limitations of previous and conventional reactor systems. Specifically, the sparger system and method of injecting a substrate feed gas into the aqueous broth of a reactor, e.g., a bioreactor, disclosed herein achieves small bubble sizes, increased gas flow rates through the sparger, and higher gas and liquid superficial velocities for high reactor / bioreactor productivity. Furthermore, the sparger system disclosed herein, in contrast to conventional systems, is configured entirely within the reactor. Summary of the Invention

[0005] The following presents a simplified summary of various embodiments described herein. This summary is not an extensive overview and is not intended to identify key or critical elements or to delineate the claims. The following summary merely presents some concepts in a simplified form as a prelude to the more detailed description that is presented below.

[0006] To overcome the limitations of the previous systems described above, as well as other limitations that will become apparent upon reading and understanding this specification, embodiments described herein are directed to systems and methods for efficiently injecting gas bubbles into liquids contained within biological and chemical reactors.

[0007] In one embodiment, a system disclosed herein relates to injecting gas bubbles into a liquid. The system can include a support plate, a plurality of annular shrouds engaged with the support plate, and a plurality of spargers disposed within the annular shroud. In some embodiments, the support plate and at least one annular shroud are integrated into a single component. In some embodiments, a gap can be defined between the inner surface of the shroud and the outer surface of the sparger. In some embodiments, the support plate, the annular shroud, and the sparger can be disposed entirely within the reactor. In some embodiments, the sparger has a length of at least 10 cm, and the width of the gap between the inner surface of the shroud and the outer surface of the sparger can be from about 1 mm to about 20 mm. In another embodiment, the support plate, the annular shroud, and the sparger can be disposed at the top or bottom of the reactor. The plurality of spargers can be engaged with a plurality of headers, and the plurality of spargers can be configured to receive a gas supply from the plurality of headers. In some embodiments, the plurality of headers can further include a baffle configured to disperse the fluid containing the liquid and the gas bubbles. In yet another embodiment, the liquid can be at least partially recirculating. In some embodiments, the support plate further comprises a plurality of perforations, and the annular shroud can be positioned within about 20 degrees of the vertical axis of the reactor. In one embodiment, the plurality of support plates can form multiple layers or stages within the reactor, and the plurality of support plates can comprise a plurality of annular shrouds, and the plurality of spargers can be positioned within the plurality of annular shrouds.

[0008] In one embodiment, the reactor may be a bioreactor comprising a liquid growth medium and a substrate comprising at least one C1 carbon source. In some embodiments, a plurality of spargers may be configured to inject bubbles of the substrate into the liquid growth medium. In another embodiment, the bioreactor may include a culture of at least one microorganism in a liquid growth medium, the culture of at least one microorganism capable of anaerobically fermenting the substrate to produce at least one fermentation product.

[0009] In yet another embodiment, the systems and methods disclosed herein relate to a method for sparging gas bubbles into a liquid, the method including: sparging a gas into a reactor containing the liquid with a plurality of spargers disposed within the reactor and configured to emit gas bubbles; directing a flow of the liquid across an outer surface of the spargers with a plurality of annular shrouds surrounding the plurality of spargers within the reactor; and shearing the gas bubbles on a surface of the plurality of spargers with the flow of the liquid across the outer surface of the spargers. In some embodiments, the method may further include accelerating the flow of the liquid across the outer surface of the spargers with a gap formed between the inner surface of the annular shroud and the outer surface of the spargers. In some embodiments, the accelerated flow of the liquid across the outer surface of the spargers may have a liquid superficial velocity of at least 0.3 m / s, and the accelerated flow of the liquid across the outer surfaces of the plurality of spargers may have a velocity of between about 0.3 m / s and about 10 m / s. In yet another embodiment, the sheared gas bubbles may have a diameter of about 0.2 mm to about 2.0 mm, and the superficial velocity of the gas phase within the vessel may be at least 0.03 m / s. In one embodiment, the superficial velocity of the gas phase within the vessel may be about 0.03 m / s to about 0.1 m / s. In yet another embodiment, the gas bubbles may be bubbles of a substrate within a bioreactor that may contain a liquid growth medium. In another embodiment, a culture of at least one microorganism in a liquid growth medium may aerobically ferment the substrate to produce at least one fermentation product.

[0010] These features, along with many others, are described in more detail below. [Brief explanation of the drawings]

[0011] The embodiments described herein and their advantages can be more fully understood by reference to the following description in consideration of the accompanying drawings, in which like reference numerals indicate like features, and in which:

[0012] [Figure 1] FIG. 1 shows a schematic representation of a dynamic sparger arrangement configured within a reactor, illustrating the downflow mode of liquid and gas bubbles, according to one embodiment of the present disclosure.

[0013] [Figure 2] FIG. 2 shows a schematic of another dynamic sparger arrangement in a reactor, illustrating the upflow mode of liquid and gas bubbles, according to another embodiment of the present disclosure.

[0014] [Figure 3] FIG. 3 shows a schematic diagram of a bioreactor system including one or more dynamic sparger system configurations and their various placements within the bioreactor, according to yet another embodiment of the present disclosure.

[0015] [Figure 4] FIG. 4 schematically illustrates another dynamic sparger configuration within a reactor, showing a horizontally positioned sparge and an upflow mode of liquid and gas bubbles, according to another embodiment of the present disclosure.

[0016] [Figure 5] FIG. 5 shows a schematic of another dynamic sparger arrangement in a reactor, showing horizontally positioned groups of spargers and an upflow mode of liquid and gas bubbles, according to another embodiment of the present disclosure.

[0017] [Figure 6] FIG. 6 shows a schematic representation of the apparatus of FIG. 5 in a top view from point 525 of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] In the following description of various embodiments, reference is made to the accompanying drawings, which form a part hereof, and which show by way of illustration how various embodiments described herein may be practiced. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the described embodiments. The embodiments described herein are capable of other embodiments and of being practiced or carried out in various ways. It is also to be understood that the phraseology and terminology used herein are for purposes of description and should not be regarded as limiting. Rather, the words and terms used herein are to be accorded their broadest interpretation and meaning. The use of "including" and "comprising" and variations thereof is meant to encompass the items listed thereafter and their equivalents, as well as additional items and their equivalents. The use of the terms "attached," "coupled," "engaged," "fluidly engaging," "coupled," "disposed," "configured," "oriented," and similar terms is meant to encompass both direct and indirect mounting, coupling, joining, disposing, and engaging.

[0019] A sparger may comprise a device that introduces gas, injected as bubbles, into a liquid to agitate it or dissolve the gas in the liquid. Examples of spargers include orifice spargers, sintered spargers, and drilled pipe spargers. In certain configurations, perforated pipe spargers may be mounted horizontally. In other embodiments, spargers may be mounted vertically or horizontally. In some embodiments, spargers may be perforated plates or rings, sintered glass, sintered steel, porous rubber pipe, porous metal pipe, porous ceramic or stainless steel pipe, perforated pipe, stainless steel perforated pipe, polymeric perforated pipe, etc. Spargers may be of various grades (porosities) and may have orifices of specific sizes to generate bubbles of specific sizes or ranges of bubble sizes.

[0020] The systems and methods disclosed herein employ a sparger configuration for generating fine bubbles, increasing the gas flow rate through the sparger and increasing the gas superficial velocity and liquid superficial velocity to achieve high reactor productivity. Increased reactor productivity can be achieved by increasing the amount of gas substrate injected into the liquid broth and available for microbial fermentation, and by increasing the specific interfacial area, defined as the total surface area of gas bubbles per unit volume of the reactor. The specific interfacial area is inversely proportional to bubble size and directly proportional to gas holdup, where gas holdup is the volume of gas present per unit volume of fluid in which the bubbles are dispersed. Reducing bubble size by generating fine bubbles increases the specific interfacial area. The increased specific interfacial area improves mass transfer from the gas to the liquid. In embodiments where the reactor is a bioreactor, improved mass transfer from the gas to the liquid ultimately provides an increased amount of substrate gas to the microorganisms for conversion into useful fermentation products, such as ethanol and other chemicals. Examples of systems and methods used to generate bubbles include those described in U.S. Patent No. 9,327,251, incorporated herein by reference in its entirety for all purposes. Higher reactor productivity can also be achieved through higher gas holdup, which is associated with an increase in the overall gas and liquid superficial velocities within the reactor. Increased gas and liquid superficial velocities can be used to break or shear sparger bubbles into the desired fine bubble size. In downward flow operation, the fine bubbles experience a buoyancy force that is less than the drag force exerted by the liquid, creating a downward flow of the overall fluid, carrying the fine bubbles and liquid downward within the reactor. The downward flow of the fluid helps to extend the residence time of the microorganisms in the liquid, extending the time for the microorganisms to convert the fine bubbles of the substrate within the bioreactor into the desired product.

[0021] The sparger system disclosed herein can use plates that engage rows of chimney shroud tubes or annular shrouds, and cylindrical spargers that are configured entirely within the reactor. Typically, the inner diameter of the annular shroud may be slightly larger than the outer diameter of the cylindrical sparger configured within the annular shroud. When liquid is pumped into the system, it is forced through a restricted space or gap between the sparger and the annular shroud. As the liquid passes through the gap, it accelerates, increasing the shear rate experienced by the liquid near the surface of the sparger. The increased shear rate reduces the bubble size of gas injected into the liquid from the sparger, creating microbubbles.

[0022] FIG. 1 schematically illustrates a bioreactor system 100 including a reactor 102. The bioreactor system 100 can include any device that can be used in a fermentation process or a chemical conversion treatment. The reactor 102 can be a vessel or container into which one or more gas and liquid streams or streams 101 can be introduced for bubble generation and / or microbubble generation, as well as for subsequent gas-liquid contact, gas absorption, biological or chemical reactions, such as microbial fermentation. The terms "microbial fermentation," "fermentation," or "gas fermentation," etc., can be interpreted as a process that receives one or more gaseous substrates and produces one or more fermentation products through the use of one or more C1-fixing microorganisms. The gaseous substrate can be derived from an industrial process, can be syngas, or any combination thereof. The syngas can be obtained from a reforming, partial oxidation, or gasification process. A "C1-fixing microorganism" is a microorganism or microbe that produces one or more fermentation products from a C1 carbon source. Typically, the microorganisms of the present disclosure are C1-fixing bacteria. A "C1 carbon source" refers to a one-carbon molecule that serves as a partial or sole carbon source for a microorganism. For example, a C1 carbon source can include one or more of CO, CO2, CH4, CH3OH, or CHO2. In one embodiment, a C1 carbon source includes one or both of CO2 and CO2. A fermentation process may include the use of one or more bioreactors. As used herein, the terms "fermentation," "fermentation process," or "fermentation reaction" are intended to encompass both the gaseous substrate growth phase and the product biosynthesis phase. Examples of C1-fixing microorganisms include Moorella, Clostridium, Ruminococcus, Acetobacterium, Eubacterium, Butyribacterium, Oxobacter, Methanosarcina, Desulfotomaculum, Clostridium autoethanogenum, and combinations thereof.In one embodiment, the C1-fixing microorganism is Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei.

[0023] In some embodiments, the liquid 101 is recirculated within the system 100. Fluids disclosed herein may include liquid, gas bubbles, and / or microbubbles. The fermentation broth or liquid 101 may include any mixture of components disclosed herein, such as a nutrient medium and a culture or one or more microorganisms. The fermentation process utilizes the fermentation broth to ferment gas bubbles or microbubbles of a substrate into one or more fermentation products. The bacterial culture may be maintained in an aqueous medium containing sufficient nutrients, vitamins, and / or minerals to allow growth of the microorganisms. The bioreactor system 100 may be comprised of one or more reactors 102 and / or columns or piping arrangements. Suitable bioreactors include, for example, a continuous stirred tank reactor (CSTR), an immobilized cell reactor (ICR), a trickle-bed reactor (TBR), a bubble column, a gas-lift fermentor, a static mixer, a recirculation loop reactor, a membrane reactor, such as a hollow fiber membrane bioreactor (HFM BR), or other vessel or other device suitable for gas-liquid contact.

[0024] The reactor 102 is not limited to any particular embodiment, such as a height-to-diameter ratio, or any particular material, but can be constructed from any material suitable for the process, such as stainless steel or PVC. The reactor 102 may include internal components, such as one or more static mixers common in biological and chemical engineering processes. The reactor 102 may also be configured with external or internal heating or cooling elements, such as a water jacket. The reactor 102 may also be in fluid contact with pumps to circulate or recirculate the liquid, gas bubbles, microbubbles, and / or fluids 101, 101a, and 111 of the system 100. As shown in FIG. 1, the dimensions of the components of the bioreactor system 100 can vary depending on the desired application or process. According to certain embodiments, the diameter of the reactor 102 can be, for example, greater than, greater than, less than, equal to, or any number between about 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, 19.0, 19.5, or about 20.0 meters. According to other embodiments, the length of the reactor 102 may be, for example, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, 19.0, 19.5, 20.5, 21.5, 22.0, 22.5, 23. It can be 0, 23.5, 24.0, 24.5, 25.0, 26.0, 27.0, 28.0, 29.0, 30.0, 31.0, 32.0, 33.0, 34.0, 35.0, 36.0, 37.0, 38.0, 39.0, 40.0, 41.0, 42.0, 43.0, 44.0, 45.0, 46.0, 47.0, 48.0, 49.0, greater than, greater than, less than, equal to, or any number between about 50.0 meters.

[0025] In the reactor 102, the gas and liquid phases, e.g., fluid 111, can flow or circulate vertically, including generally downward flow, as shown in Figure 2, or generally upward flow, for example. As shown in the reactor 102 of Figure 1, the gas and liquid phases in fluid 111 can flow generally downward within the reactor 102. The liquid superficial velocity V within the reactor L is expressed by the following formula V L =Q L / A C where Q L is the volumetric flow rate of the liquid (m 3 / s) and A C is the cross-sectional area of the reactor. Therefore, the liquid superficial velocity represents the velocity of the liquid phase when it occupies the entire cross-sectional area of the reactor. For the same liquid flow rate, the gas flow rate can be changed depending on the actual application. The superficial velocity of the gas phase, V G is expressed by the following formula V G =Q G / A C where Q G is the volumetric flow rate (m 3 / s) and A Cis the cross-sectional area of the reactor. Thus, the gas superficial velocity represents the velocity of the gas phase when it occupies the entire cross-sectional area of the reactor. In some embodiments, the superficial velocity of the gas phase within the vessel may be at least 0.03 m / s. In other embodiments, the superficial velocity of the gas phase within the vessel may be from about 0.03 m / s to about 0.1 m / s. In still other embodiments, the superficial velocity of the gas phase within the vessel may be, for example, greater than, less than, equal to, or any value between about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.12, 0.13, 0.14, or any value between about 0.15 m / s. In yet other embodiments, the superficial velocity of the gas phase within the vessel may be, for example, from about 0.03 to 0.06 m / s. In one embodiment, the liquid superficial velocity may be at least about 0.3 m / s. As noted above, increasing the gas and liquid superficial velocities has the beneficial effect of breaking up or shearing the sparger bubbles to the desired fine bubble size.

[0026] The bioreactor system 100 can include at least one sparger 106 for introducing a gaseous substrate, injected as bubbles, into the liquid 101 and for agitating or dissolving the gas within the liquid 101. The sparger 106 can be mounted in a horizontal or vertical position. In some embodiments, the sparger 106 can be an orifice sparger, a sintered sparger, a perforated pipe sparger, a perforated plate or ring, sintered glass, sintered steel, porous rubber pipe, porous metal pipe, porous ceramic or stainless steel pipe, perforated pipe, stainless steel perforated pipe, or a polymeric perforated pipe. The sparger 106 can be of various grades (porosities) and can have orifices of specific sizes to generate bubbles of a specific size. The porosity of the sparger is typically designed to avoid weeping, which occurs when the gas flowing through the pores does not have enough kinetic energy to maintain a liquid head above the sparger pores. The working velocity of the gas through the pores is designed to be significantly faster than the weeping velocity to ensure uniform sparging. The sparger 106 may have a length of, for example, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or any number between about 50 cm. The bioreactor system 100 can be adapted to receive a gaseous substrate comprising a C1 carbon source that is injected as bubbles 103 into the liquid broth 101 by the sparger 106 through the header 108.

[0027] Bioreactor system 100 may include a support plate 104. Support plate 104 may be configured to engage at least one annular shroud 105. The diameter of annular shroud 105 may be larger than the diameter of sparger 106. Thus, sparger 106 may be configured to be disposed within annular shroud 105 that defines a gap or restricted region 107 between an outer wall of sparger 106 and an inner wall of annular shroud 105. In some embodiments, the width of gap 107 is about 1-20 mm. In other embodiments, the width of the gap 107 can be, for example, greater than, greater than, less than, equal to, or any number between about 0.25, 0.50, 0.75, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or greater than, greater than, less than, equal to, or about 50 mm.

[0028] The sparger 106 and annular shroud 105 may be located entirely within the interior of the reactor 102. In some embodiments, the support plate 104, annular shroud 105, and sparger 106 may be located at the top or upper portion of the reactor 102. Locating the support plate 104, annular shroud 105, and sparger 106 at the top of the reactor 102 can have the added benefit of reducing hydrostatic pressure at the top of the reactor 102, facilitating enhanced gas-to-liquid mass transfer rates while reducing energy requirements. In some embodiments, the systems and methods disclosed herein provide a flow path for at least 125 m 3 In another embodiment, the gas-to-liquid mass transfer rate is, for example, about 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, or greater, greater than, less than, equal to, or up to about 200 m / min. 3 / min. Alternatively, the support plate 104, the annular shroud 105, and the sparger 106 may be located at the bottom or lower portion of the reactor 102. In yet other embodiments, the support plate 104, the annular shroud 105, and the sparger 106 may be located in the upper one-third, upper two-thirds, or lower one-third of the reactor 102. In some embodiments, the annular shroud 105 may be fabricated from standard pipe, seamless tubing, welded tubing, custom-made tubing, or a combination thereof. The components of the annular shroud 105 may be bonded or fastened to the support plate 104 by shielded metal arc welding, gas tungsten arc welding, gas metal arc welding, flux-cored arc welding, submerged arc welding, electroslag welding, or may be fabricated by weld-free tube sheet joint field rolling techniques. In another embodiment, silver brazing is avoided to prevent damage to the microorganisms during fermentation. In yet other embodiments, the support plate 104 may include perforations 109 to facilitate removal or evacuation of solid debris. In some embodiments, multiple support plates 104 may form multiple vertical layers within the reactor 102. Each vertical layer of support plates 104 may include multiple annular shrouds 105 and multiple spargers 106. In still other embodiments, the annular shroud 105 may be positioned approximately perpendicular to the support plate 104. In other embodiments, the annular shroud may be positioned at, for example, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or any number between ... greater than, greater than, less than, equal to, or about 30 degrees from the vertical axis of the reactor 102.

[0029] As shown in FIG. 1 , liquid broth 101 enters the top of reactor 102. A gas substrate is injected into liquid 101 within reactor 102 by sparger 106, which is connected to gas supply / header 108. At least a portion of the flow of liquid 101 is directed across the exterior surface of sparger 106. In some embodiments, substantially all of the flow of liquid 101 is directed across the exterior surface of sparger 106. As liquid 101 is forced into gap 107 defined by annular shroud 105 and the exterior wall of sparger 106, the liquid accelerates as it travels the vertical length of sparger 106 and annular shroud 105. The accelerated liquid 101a shears the injected gas bubbles on the surface of sparger 106, breaking the injected gas bubbles into fine bubbles 103. The sheared fine bubbles 103 may have a diameter of about 0.2 to about 2.0 mm. According to another embodiment, the diameter of the microbubbles may be, for example, about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.10, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.19, 2.20, 2.21, 2.22, 2.23, 2.24, 2.25, 2.26, 2.27, 2.28, 2.29, 2.30, 2.31, 2.32, 2.33, 2.34, 2.35, 2.36, 2.37, 2.38, 2.39, 2.40, 2.41, 2.42, 2.43, 2.44, 2.45, 2.46, 2.47, The distance can be any number between 5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, greater than, greater than, less than, equal to, or about 5.0 mm. The accelerated flow of liquid 101a across the exterior surface of sparger 106 may have a velocity of at least 0.3 m / s. In another embodiment, the accelerated flow of liquid 101a across the exterior surface of sparger 106 may have a velocity of about 0.3 to about 10 m / s.In other embodiments, the accelerated flow of liquid 101a across the exterior surface of sparger 106 may have a liquid superficial velocity of, for example, about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or greater, greater than, less than, equal to, or any number between about 30 m / s.

[0030] According to other embodiments, the sparger 106 may be located at the bottom of the reactor 102 or in the middle of the reactor 102. According to another embodiment, the sparger 106 may be positioned horizontally. According to yet another embodiment, the sparger 106 may be located in multiple locations throughout the reactor 102, including the top, middle, and bottom of the reactor 102. According to yet another embodiment, the sparger 106 may be a ring sparger or a perforated pipe sparger. According to one embodiment, individual spargers 106 and headers 108 may be configured as modular components to facilitate reactor structure and / or component replacement, general maintenance, cleaning, or to enable a scalable reactor system depending on requirements. According to other embodiments, multiple spargers 106 and headers 108 may be stacked within the reactor 102. In yet other embodiments, the sparger 106 may be configured to extend vertically below the header 108, or the sparger 106 may be configured to extend vertically above the header 108. According to another embodiment, a single stage or stack of headers 108 may comprise any number of individual headers 108, for example, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or more, greater than, less than, equal to, or between about 20. In some embodiments, the headers 108 may be configured as annular gas feeds. In yet another embodiment, one or more fluid distributors (not shown) may be used to distribute the fluid flow 111 throughout the reactor 102. In one embodiment, the fluid distributor is positioned near the fluid outlet of the gap 107. The fluid distributor may be an impermeable plate, vane, or trough. The fluid distributor may be attached to the end of the sparger 106 and extend below the sparger 106 and at least partially across the area below the gap 107.

[0031] FIG. 2 illustrates another configuration of the sparger system of FIG. 1. As shown in FIG. 2, liquid 201 and fluid 211, having both gas and liquid phases, can flow or circulate in a generally vertically upward direction within the loop reactor system. A support plate 204 is contained within the reactor. Again, support plate 204 can be configured to engage at least one annular shroud 205. The diameter of the annular shroud 205 can be larger than the diameter of the sparger 206. Thus, the sparger 206 can be configured to be disposed within the annular shroud 205, defining a gap or restricted region 207 between the outer wall of the sparger 206 and the inner wall of the annular shroud 205. The sparger 206 can be fluidly engaged with a header 208 through an extension 213 extending therefrom. The header 208 can be configured to receive a gaseous substrate injected into the liquid broth 201 by the sparger 206. The liquid broth 201 can enter the reactor from the bottom. At least a portion 201a of the liquid 201 is directed across the outer surface of the sparger 206. In some embodiments, substantially all of the flow of the liquid 201 is directed across the outer surface of the sparger 206. When the liquid 201 is forced into the gap 207 defined by the annular shroud 205 and the outer wall of the sparger 206, the liquid 201 accelerates as it moves vertically upward through the gap 207. The accelerated liquid 201a shears the injected gas bubbles on the outer surface of the sparger 206, generating microbubbles 203. A vertical extension 213 extending from the header 208 can include baffles 215 configured to redirect or deflect the flow of the fluid 211 to prevent dead zones of stagnant fluid. The support plate 204 can also include holes or perforations 217 for drainage and circulation of stagnant fluid areas. In one embodiment, the annular shroud may be positioned within a guide (not shown) to control its alignment with the concentric sparger.

[0032] As shown in FIG. 2, locating the header 208 above the sparger 206 is advantageous because this configuration does not impede the upward flow of liquid and gas bubbles. Furthermore, system components, including the sparger 106, may be modular, facilitating the construction, maintenance, and replacement of components within the system. In some embodiments, the header 208 may be permanently installed within the reactor, and the sparger 106 may then be attached to the vertical extension 213 and / or the header 208. The sparger 206 and vertical extension 213 may be a series of individual parts / components that are easily transported and inserted into the reactor vessel and individually coupled to the vessel. Similar to the system shown in FIG. 1, the system shown in FIG. 2 may include multiple headers 208, and multiple support plates 204 may form multiple vertical layers within the reactor. Each vertical layer of support plates 204 may include multiple annular shrouds 205 and multiple spargers 206 in fluid engagement with the multiple vertical extensions 213 and the header 208. In some embodiments, the reaction vessel contains, for example, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 20, 21, 22 Any number of vertical layers of support plates may be provided, such as 6, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or more, greater than, less than, equal to, or between about 100.In some embodiments, each vertical layer may have a thickness of, for example, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 ,60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 1 18, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 1, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, or greater, greater than, less than, equal to, or between about 200 spargers and / or annular shrouds. Again, such sparger configurations may be used in reactor systems 100 and 200 described in both Figures 1 and 2.

[0033] According to other embodiments, the sparger 206 may be located at the bottom of the reactor or in the middle of the reactor. According to another embodiment, the sparger 206 may be positioned horizontally. According to yet another embodiment, the sparger 206 may be located in multiple locations throughout the reactor, including the top, middle, and bottom of the reactor. According to yet another embodiment, the sparger 206 may be a ring sparger or a perforated pipe sparger. According to one embodiment, individual spargers 206 and headers 208 may be configured as modular components to facilitate reactor structure and / or component replacement, general maintenance, cleaning, or to enable a scalable reactor system depending on requirements. According to other embodiments, multiple spargers 206 and headers 208 may be stacked within the reactor. In yet other embodiments, the sparger 206 may be configured to extend vertically below the header 208, or the sparger 206 may be configured to extend vertically above the header 208. According to alternative embodiments, a single stage or stack of headers 208 may comprise any number of individual headers 208, for example, from about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or more, greater than, less than, equal to, or between about 20. In some embodiments, the headers 208 may be configured as an annular gas supply.

[0034] FIG. 3 illustrates a loop bioreactor system 300 and method incorporating the sparger shroud system disclosed herein. Liquid broth circulating within reactor 304 is injected with a gas substrate by one or both of sparger shroud assemblies 316 and 306. Exemplary details of a suitable sparger shroud assembly are illustrated in FIGS. 1 and 2. In one embodiment, at least a portion of the flow of liquid broth 301 entering riser section 302 of reactor 304 is forced through a gap defined by the annular shroud and the outer wall of the sparger of sparger shroud assembly 316. Liquid broth 301 accelerates as it moves through the gap defined by the sparger and the annular shroud of sparger shroud assembly 316. The accelerated liquid broth 301 shears the injected gas bubbles on the surface of the sparger, thereby generating microbubbles. The resulting fluid 311, containing the liquid broth and microbubbles, flows upward through the riser section 302 of the reactor 304, exiting the riser section 302 and entering the separation section 308. At least a portion of the fluid 311 exits the separation section 308 and enters the downcomer 312. At this point, the fluid 311 may be depleted of the gas substrate, forming a gas substrate-depleted liquid broth 321. Optionally, the downcomer 312 may include at least one sparger shroud assembly 306, as disclosed herein. The sparger shroud assembly 306, located within the downcomer 312, may inject microbubbles of the gas substrate into the substrate-depleted liquid broth 321 to provide additional substrate for the microorganisms therein and prolong their survival. The bioreactor system 300 may include a pump 314 to circulate the liquid broth 301, the fluid 311, and the substrate-depleted liquid broth 321 throughout the bioreactor system 300.

[0035] As shown in FIG. 4 , liquid broth 401 enters the bottom of reactor 402. A gas substrate is injected into liquid 401 within reactor 402 by sparger 406, which connects to gas supply / header 408. At least a portion of the flow of liquid 401 is directed across the exterior surface of sparger 406. In some embodiments, substantially all of the flow of liquid 401 is directed across the exterior surface of sparger 406. In other embodiments, a portion of liquid flow 401 bypasses the exterior surface of sparger 406 through passageway 403. As liquid 401 is forced into gap 407 defined by annular shroud 405 and the exterior wall of sparger 406, the liquid accelerates as it moves around the periphery of horizontally positioned sparger 406 and annular shroud 405 or across a vertical plane. The accelerated liquid 401a shears the injected gas bubbles on the surface of sparger 406, breaking the injected gas bubbles into fine bubbles 409. The sheared microbubbles 409 may have a diameter of about 0.2 to about 2.0 mm. According to another embodiment, the diameter of the microbubbles may be, for example, about 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.1, 2.2, 2.4, 2.5, 2.6 ...7, 2.8, 2.9, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7 The diameter of the microbubble-laden fluid 401a may be any number between 5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or greater than, greater than, less than, equal to, or about 5.0 mm. The flow of the microbubble-laden fluid continues in an upflow mode 420. The accelerated flow of the liquid 401a across the exterior surface of the sparger 406 may have a velocity of at least 0.3 m / s. In another embodiment, the accelerated flow of liquid 401a across the exterior surface of sparger 406 may have a velocity of about 0.3 to about 10 m / s.In other embodiments, the accelerated flow of liquid 401a across the exterior surface of sparger 406 may have a liquid superficial velocity of, for example, about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or greater, greater than, less than, equal to, or any number between about 30 m / s.

[0036] According to other embodiments, the sparger 406 may be located at the bottom of the reactor 402 or in the middle of the reactor 402. FIG. 4 illustrates an embodiment in which the sparger 406 is positioned horizontally. According to yet another embodiment, the sparger 406 may be located in multiple locations throughout the reactor 402, including at the top, middle, and bottom of the reactor 402. According to yet another embodiment, the sparger 406 may be a ring sparger or a perforated pipe sparger. According to one embodiment, individual spargers 406 and headers 408 may be configured as modular components to facilitate reactor structure and / or component replacement, general maintenance, cleaning, or to enable a scalable reactor system depending on requirements. According to other embodiments, multiple stages of spargers 406 and headers 408 may be stacked within the reactor 402. In yet other embodiments, the sparger 406 may be configured to extend horizontally across the cross section of the reactor 402. According to another embodiment, a single stage or stack of headers 408 may include any number of individual headers 408 or vertical extensions 413, for example, from about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or more, greater than, less than, equal to, or between about 20. In some embodiments, the headers 408 may be configured as an annular gas supply.

[0037] As further shown in FIG. 4 , locating the header 408 above the sparger 406 is advantageous because this configuration does not impede the upward flow of liquid and gas bubbles. In FIG. 4 , the sparger 406 is positioned horizontally within the reactor 402. Furthermore, system components, including the sparger 406, may be modular, facilitating the construction, maintenance, and replacement of components within the system. In some embodiments, the header 408 may be permanently installed within the reactor or may have a vertical extension 413. The sparger 406, header 408, and vertical extension 413 may be a series of individual parts / components that are easily transported and inserted into the reactor vessel and individually coupled to the vessel. The system shown in FIG. 4 may include multiple headers 408 and multiple spargers 406 that can form multiple layers within and along the vertical direction of the reactor. Each layer may include multiple annular shrouds 405 and multiple spargers 406 in fluid engagement with the multiple vertical extensions 413 and the header 408. In certain embodiments, the reaction vessel may contain, for example, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 , 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or more, greater than, less than, equal to, or between about 100 vertical layers of spargers, annular shrouds, and header sets.In some embodiments, each vertical layer may have a thickness of, for example, about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 ,60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 1 18, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166 16, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, or greater than, greater than, less than, equal to, or between about 200. Again, such sparger configurations may be used in reactor systems 400, 500, and 600 described in Figures 4, 5, and 6.

[0038] According to other embodiments, the sparger 406 may be located at the bottom of the reactor or in the middle of the reactor. According to FIG. 4, the sparger 406 is positioned horizontally. According to yet another embodiment, the sparger 406 may be located in multiple locations throughout the reactor, including at the top, middle, and bottom of the reactor. According to yet another embodiment, the sparger 406 may be a ring sparger or a perforated pipe sparger. According to one embodiment, individual spargers 406 and headers 408 may be configured as modular components to facilitate reactor structure and / or component replacement, general maintenance, cleaning, or to enable a scalable reactor system depending on requirements. According to other embodiments, multiple stages of spargers 406 and headers 408 may be stacked within the reactor. According to alternative embodiments, a single stage or stack of headers 408 may comprise any number of individual headers 408, for example, from about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or more, greater than, less than, equal to, or between about 20. In some embodiments, the headers 408 may be configured as an annular gas supply.

[0039] FIG. 5, a side view, and FIG. 6, a top view of FIG. 5, illustrate an embodiment in which multiple spargers 506 are disposed within the same annular shroud 505. Disposing multiple spargers 506 within the same annular shroud 505 reduces piping and header or manifold connections. Similar to FIG. 4, liquid broth 501 enters the bottom of reactor 502. Gas substrate is injected into liquid 501 within reactor 502 by sparger 506, which connects to gas supply / header 508. At least a portion of the flow of liquid 501 is directed across the exterior surface of sparger 506. In some embodiments, substantially all of the flow of liquid 501 is directed across the exterior surface of sparger 506. In other embodiments, a portion of liquid flow 501 bypasses the exterior surface of sparger 506 through passageway 503. As liquid 501 is forced into gap 507 defined by the outer wall of annular shroud 505 and sparger 506, the liquid accelerates as it moves around the horizontally disposed sparger 506 and annular shroud 505 or across a vertical plane. The accelerated liquid 501a shears the injected gas bubbles on the surface of sparger 506, breaking them down into fine bubbles 509, as described above. Figures 5 and 6 show three spargers 506 positioned within a single annular shroud 505. The number of spargers positioned within a single annular shroud can vary from about 2 to about 10.

[0040] While the present disclosure has been described in several specific embodiments, many additional modifications and variations will be apparent to those skilled in the art. It is therefore to be understood that the present disclosure can be practiced otherwise than as specifically described without departing from the scope and spirit of the present disclosure. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive. The scope of the present disclosure should therefore be determined not by the illustrated embodiments, but by the appended claims and their equivalents. Embodiment

[0041] Embodiment 1: 1. A sparger system for injecting gas bubbles into a liquid, comprising: A support plate; a plurality of annular shrouds engaging the support plate; a plurality of spargers disposed within the annular shroud, the plurality of spargers defining gaps between an inner surface of the annular shroud and an outer surface of a corresponding sparger; A sparger system in which a support plate, an annular shroud, and a sparger are disposed inside the reactor.

[0042] Embodiment 2: 2. The system of embodiment 1, wherein the support plate and the annular shroud are integrated into a single component.

[0043] Embodiment 3: 3. The system of embodiment 1 or 2, wherein the two or more spargers are disposed within a single annular shroud.

[0044] Embodiment 4: 4. The system of any one of embodiments 1-3, wherein the sparger has a length of at least 10 cm.

[0045] Embodiment 5: 5. The system of any one of embodiments 1 to 4, wherein the gap is from about 1 mm to about 20 mm.

[0046] Embodiment 6: 6. The system of any one of embodiments 1-5, wherein the support plate, annular shroud, and sparger are located at the top or bottom of the reactor.

[0047] Embodiment 7: 7. The system of any one of embodiments 1-6, wherein the multiple spargers are configured to engage the multiple headers, and the multiple spargers are configured to receive gas feed from the multiple headers.

[0048] Embodiment 8: 8. The system of any one of embodiments 1 to 7, wherein the multiple headers further comprise baffles configured to disperse fluid containing liquid and air bubbles.

[0049] Embodiment 9: 9. The system of embodiment 8, wherein the liquid is at least partially a recirculating liquid.

[0050] Embodiment 10: 10. The system of any one of embodiments 1 to 9, wherein the support plate further comprises a plurality of perforations.

[0051] Embodiment 11: 11. The system of any one of embodiments 1-10, wherein the annular shroud is positioned within about 20 degrees of the vertical axis of the reactor.

[0052] Embodiment 12: 12. The system of any one of embodiments 1-11, further comprising at least one additional support plate arranged to form multiple vertical layers within the reactor interior, the at least one additional support plate engaging the multiple annular shrouds.

[0053] Embodiment 13: 13. The system of any one of embodiments 1 to 12, wherein the reactor is a bioreactor.

[0054] Embodiment 14: the reactor is a bioreactor, a liquid growth medium; a substrate comprising at least one C1 carbon source, wherein a plurality of spargers are configured to inject bubbles of the substrate into a liquid growth medium; 13. The system of any one of embodiments 1-12, wherein the system is a bioreactor comprising: a culture of at least one microorganism in a liquid growth medium, wherein the culture of the at least one microorganism anaerobically ferments a substrate to produce at least one fermentation product.

[0055] Embodiment 15: 1. A method for sparging gas bubbles into a liquid, comprising: sparging a gas into a reactor containing a liquid with a plurality of spargers disposed within the reactor and configured to emit gas bubbles; directing the flow of liquid across an exterior surface of the spargers with a plurality of annular shrouds surrounding the plurality of spargers within the reactor; shearing the gas bubbles at the surface of the plurality of spargers by flowing liquid across the exterior surfaces of the spargers.

[0056] Embodiment 16: 16. The method of embodiment 15, further comprising accelerating the flow of liquid across the outer surface of the sparger by a gap formed between the inner surface of the annular shroud and the outer surface of the sparger.

[0057] Embodiment 17: 17. The method of embodiment 15 or 16, wherein the accelerated flow of liquid across the exterior surface of the sparger has a liquid superficial velocity of at least 0.3 m / s.

[0058] Embodiment 18: 18. The method of any one of embodiments 15-17, wherein the accelerated flow of liquid across the exterior surfaces of the plurality of spargers has a velocity of from about 0.3 m / s to about 10 m / s.

[0059] Embodiment 19: 19. The method of any one of embodiments 15-18, wherein the sheared bubbles have a diameter of about 0.2 mm to about 2.0 mm.

[0060] Embodiment 20: 20. The method of any one of embodiments 15 to 19, wherein the superficial velocity of the gas phase in the vessel is at least 0.03 m / s.

[0061] Embodiment 21: 20. The method of any one of embodiments 15 to 19, wherein the superficial velocity of the gas phase in the vessel is from about 0.03 m / s to about 0.1 m / s.

[0062] Embodiment 22: 22. The method of any one of embodiments 15-21, wherein the bubbles are bubbles of a substrate in a bioreactor containing a liquid growth medium, and a culture of at least one microorganism in the liquid growth medium aerobically fermenting the substrate to produce at least one fermentation product.

Claims

1. 1. A sparger system for injecting gas bubbles into a liquid, comprising: A support plate; a plurality of annular shrouds engaging the support plate; a plurality of spargers disposed within the annular shroud, the plurality of spargers defining gaps between an inner surface of the annular shroud and an outer surface of a corresponding sparger; a plurality of headers engaging said plurality of spargers; Equipped with the support plate, the annular shroud, and the sparger are disposed within a reactor; the plurality of spargers are configured to receive gas supply from the plurality of headers; The plurality of headers or vertical extensions extending from the plurality of headers further comprise baffles configured to disperse fluid including liquid and gas bubbles.

2. The system of claim 1 , wherein the support plate and the annular shroud are integrated into a single component.

3. The system described in claim 1, wherein two or more of the plurality of spargers are positioned within a single annular shroud of the plurality of annular shrouds.

4. 10. The system of claim 1, wherein the sparger has a length of at least 10 cm.

5. The system of claim 1 , wherein the gap is between 1 mm and 20 mm.

6. 10. The system of claim 1, wherein the support plate, the annular shroud, and the sparger are located at the top or bottom of the reactor.

7. The system of claim 1 , wherein the liquid is at least partially a recirculating liquid.

8. The system of claim 1 , wherein the support plate further comprises a plurality of perforations.

9. 10. The system of claim 1, wherein the annular shroud is positioned within 20 degrees of a vertical axis of the reactor.

10. A sparger system for injecting gas bubbles into a liquid, comprising: A support plate; a plurality of annular shrouds engaging the support plate; a plurality of spargers disposed within the annular shroud, the plurality of spargers defining gaps between an inner surface of the annular shroud and an outer surface of a corresponding sparger; Equipped with the support plate, the annular shroud, and the sparger are disposed within a reactor; The system further comprises at least one additional support plate arranged to form a plurality of vertical layers within the interior of the reactor, the at least one additional support plate engaging the plurality of annular shrouds.

11. The system of claim 1 , wherein the reactor is a bioreactor.

12. The reactor is a bioreactor, a liquid growth medium; a substrate comprising at least one C1 carbon source, wherein the plurality of spargers are configured to inject bubbles of the substrate into the liquid growth medium; 10. The system of claim 1, wherein the system is a bioreactor comprising: a culture of at least one microorganism in a liquid growth medium, the culture of at least one microorganism anaerobically fermenting the substrate to produce at least one fermentation product.

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