Reactor for algae cultivation

Abstract

The reactor for dissolving carbon dioxide in algae includes a means for introducing carbon dioxide into a reaction chamber, an inlet spray nozzle configured to spray an algae-containing growth medium into the reaction chamber, and a valve configured to control the outflow of algae. Within the reaction chamber, the carbon dioxide dissolves in the growth medium, causing algae growth. The algae accumulate at the bottom of the reaction chamber, forming an algae column that substantially prevents carbon dioxide from being released into the environment.

Description

[Technical Field]

[0001] The present invention relates to a reactor for dissolving carbon dioxide in a growth medium containing algae. [Background technology]

[0002] Algae farms and bioreactors that produce algae for fuel, biochemicals, and biomass food are considered carbon-negative industries. Because the carbon dioxide absorbed by algae typically comes from the surrounding atmosphere and is converted into carbohydrates and lipids, algae farming can be part of a carbon dioxide sequestration cycle. Literature and industry publications have documented the importance of increasing carbon dioxide levels in photobioreactors and culture raceways to promote algal biomass growth.

[0003] Traditional methods, such as bubbling using a sparger system or a bubbling chamber, are used to dissolve carbon dioxide in the algae culture medium. However, due to the inefficiency of gas-liquid mixing, approximately 90% or more of the carbon dioxide is released into the environment. This release of carbon dioxide into the environment negatively impacts the carbon footprint analysis of a particular algae culture project. Summary of the Invention

[0004] It is therefore an object of the present invention to overcome the problem of carbon dioxide being released into the environment and to provide a reactor suitable for use in dissolving carbon dioxide in algae.

[0005] In one aspect of the present invention, a reactor for cultivating algae is provided, comprising: a means for introducing carbon dioxide into a reaction chamber within the reactor; an inlet spray nozzle located at an upper portion of the reactor and configured to spray a growth medium containing algae into the reaction chamber; and a valve located at the bottom of the reactor and configured to control the outflow of algae, wherein the carbon dioxide dissolves in the growth medium, causing algae growth, which accumulates at the bottom of the reaction chamber, forming an algal column and substantially preventing carbon dioxide from being released into the environment.

[0006] In one embodiment, the reaction chamber is pre-filled with carbon dioxide at a pressure of up to 2 bar before the algae-containing growth medium is introduced into the reaction chamber.

[0007] In one embodiment, the reactor further comprises at least one optical sensor for regulating the height of the algae column within the reaction chamber.

[0008] In one embodiment, the reactor further comprises a pressure regulator disposed in the means for introducing carbon dioxide to regulate the pressure of carbon dioxide within the reaction chamber.

[0009] In one embodiment, the reactor further comprises a pump mounted downstream of the inlet spray nozzle to pump the algae-containing growth medium at a minimal flow rate to form pressurized particles of growth medium that enter the reaction chamber.

[0010] Advantageously, the particulates in the growth media provide additional surface area for carbon dioxide to dissolve and form bicarbonate ions, which are consumed by the algae as building blocks of carbon.

[0011] Preferably, the growth medium further comprises saline.

[0012] In one embodiment, the rate at which carbon dioxide dissolves into bicarbonate ions can be changed by adjusting the pressure of carbon dioxide in the reaction chamber.

[0013] Advantageously, the algae removed from the reactor can be utilized in algae farms or bioreactors for the production of fuels, biochemicals, and biomass food products.

[0014] Advantageously, this reactor consumes 39% to 53% of the carbon dioxide when compared to conventional sparger and bubbling systems and significantly prevents carbon dioxide from leaking to the environment (less than 0.02% loss).

[0015] In one aspect of the present invention, there is provided the use of a reactor for dissolving carbon dioxide in a growth medium containing algae for algae cultivation. [Brief explanation of the drawings]

[0016] It will be convenient to further describe the invention with reference to the accompanying drawings, which illustrate possible configurations of the invention. Other configurations of the invention are possible, and therefore the particularity of the accompanying drawings should not be understood as superseding the generality of the foregoing description of the invention.

[0017] [Figure 1] 1 shows a reactor of the present invention. [Figure 2a] The rate of carbon dioxide consumption by the reactor of the present invention is compared to a conventional bubbling system when fresh water is utilized. [Figure 2b] The bicarbonate production and pH levels of the reactor of the present invention are compared to a conventional bubbling system when fresh water is utilized. [Figure 3a] The carbon dioxide consumption rate by the reactor of the present invention is compared to that by a conventional bubbling system when salt water is utilized. [Figure 3b] The bicarbonate production and pH levels of the reactor of the present invention are compared to a conventional bubbling system when salt water is utilized. DETAILED DESCRIPTION OF THE INVENTION

[0018] Referring to Figure 1, the reactor (100) is a long column equipped with a means for introducing carbon dioxide (102) into a reaction chamber (104), an inlet spray nozzle (106) located at the top of the reactor for spraying the algae-containing growth medium into the reaction chamber, and a valve (108) located at the bottom of the reactor for controlling the exit of algae from the reaction chamber. Preferably, the reactor is a vertically oriented polymer-based column 1-2 meters in height. The reaction chamber is pre-filled with carbon dioxide at a pressure of up to 2 bar prior to introducing the growth medium into the reaction chamber.

[0019] A pump installed downstream of the inlet spray nozzle continuously pumps the algae-containing growth medium into the inlet spray nozzle at a minimum flow rate, forming atomized particles of growth medium that drip and collect in the reaction chamber, where they are mixed with the high-pressure carbon dioxide. Preferably, the flow rate of growth medium into the reaction chamber is 0.85 lpm.

[0020] Mixing within the reaction chamber begins at the inlet spray nozzle, where gaseous CO2 is forced to dissolve into the growth media particles using pressure as a driving force. Mixing continues within the chamber based on the contact area between the collected media and the pressurized CO2. The media particles increase the surface area for carbon dioxide to dissolve and form bicarbonate ions. The bicarbonate ions dissolved in the media are consumed by the algae as building blocks of carbon.

[0021] The algae accumulate at the bottom of the reaction chamber, forming an algae column. To ensure proper mixing with the carbon dioxide, the algae column must occupy 20-50% of the reaction chamber. Furthermore, the algae column essentially prevents carbon dioxide from escaping through a valve and being released into the environment. The valve opens and closes based on the pressure and water level of the algae column within the reaction chamber. The algae removed from the reactor can be utilized in algae cultivation farms and bioreactors to produce fuel, biochemicals, and biomass food.

[0022] The reactor further includes at least one optical sensor for adjusting the height of the algae column in the reaction chamber, and a pressure regulator is disposed in the carbon dioxide introduction means to adjust the carbon dioxide pressure in the reaction chamber, thereby affecting the rate of carbon dioxide dissolution.

[0023] Figures 2a and 2b show experimental results for the efficiency of the reactor (supplied with freshwater) in dissolving carbon dioxide into bicarbonate ions compared to a conventional bubbling system. At carbon dioxide supply pressures below 0.25 bar, the reactor consumes less carbon dioxide (44% more than the bubbling system). At carbon dioxide supply pressures between 0.5 and 0.7 bar, the reactor consumes more carbon dioxide than the bubbling system, consuming only 36% less carbon dioxide to produce the same concentration of bicarbonate ions (Figure 2b). At a carbon dioxide supply pressure of 1 bar, the reactor is more efficient than the bubbling system, consuming only 44% less carbon dioxide to produce a similar concentration of bicarbonate ions.

[0024] Figures 3a and 3b show experimental results for the efficiency of the reactor (fed with saltwater) in dissolving carbon dioxide into bicarbonate ions compared to a conventional bubbling system. At carbon dioxide supply pressures of 0.5-0.7 bar, the reactor is more efficient compared to the bubbling system, consuming only 39% of the carbon dioxide while producing 76% more bicarbonate ions (Figure 3b). At a carbon dioxide supply pressure of 1 bar, the reactor is more efficient compared to the bubbling system, consuming only 53% more carbon dioxide to produce a similar concentration of bicarbonate ions (Figure 3b).

[0025] Salt water was primarily used as the growth medium for the selected algal strains versus freshwater as a standard of comparison.

[0026] The reactor of the present invention consumes 39% to 53% less carbon dioxide than conventional sparger and bubbling systems and can substantially prevent carbon dioxide from leaking to the environment (loss of less than 0.02%). [Explanation of symbols]

[0027] 100 Reactors 102 Carbon dioxide 104 Reaction Chamber 106 Inlet spray nozzle 108 Valve

Claims

1. A reactor (100) for cultivating algae, comprising: a means for introducing carbon dioxide (102) into a reaction chamber (104) within the reactor; an inlet spray nozzle (106) positioned at the top of the reactor and configured to spray algae-containing growth medium into the reaction chamber; a valve (108) located at the bottom of the reactor and configured to control the outflow of algae; Equipped with A reactor (100) for culturing algae, in which carbon dioxide dissolves in the growth medium, causing algae to grow, and the algae accumulate at the bottom of the reaction chamber to form an algae column, substantially preventing carbon dioxide from being released into the environment.

2. 10. The reactor of claim 1, wherein the reaction chamber is pre-filled with carbon dioxide at a pressure of up to 2 bar.

3. 10. The reactor of claim 1, further comprising at least one optical sensor for adjusting the height of the algae column within the reaction chamber.

4. 10. The reactor of claim 1, further comprising a pressure regulator disposed in said means for introducing carbon dioxide to regulate the pressure of carbon dioxide within said reaction chamber.

5. 10. The reactor of claim 1, further comprising a pump mounted downstream of the inlet spray nozzle to pump algae-containing growth media at a minimal flow rate to form small pressurized growth media particles that enter the reaction chamber.

6. 10. The reactor of claim 1, wherein the growth medium further comprises saline.

7. 2. The reactor of claim 1, wherein the rate at which carbon dioxide dissolves into bicarbonate ions is changed by adjusting the pressure of carbon dioxide in the reaction chamber.

8. 10. Use of the reactor of claim 1 for dissolving carbon dioxide in a growth medium containing algae for algae cultivation.

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