Patent Application
20160102025
The present invention is directed to a plasma discharge reactor, and specifically, a plasma discharge reactor designed to provide plasma-catalytic enhanced water that is useful for increasing plant growth and yield.
With increasing populations and decreased crop acreage, providing adequate resources, particularly food, is becoming not only an economic issue, but a moral issue as well. One way to address this issue is by increasing the efficiency of farmlands through increased plant growth and yield. Innovative solutions are needed to address this challenge.
A number of variables affect plant development and growth. One factor, which plays a particularly important role, is water chemical composition. More specifically, water pH and nutrient content, play a crucial role in plant development and growth. Today, soil pH and nutrient content are controlled through the addition of various fertilizers that contain necessary buffers and nutrients. These fertilizers, however, suffer from drawbacks such as slow and unbalanced nutrient delivery, untidy application, and undesired runoff.
Thus, there is a need for improved methods and technologies for the production and delivery of chemically enhanced water to improve crop growth and yield.
It is an aspect of the present invention to provide a water processing system comprising
It is another aspect of the present invention to provide a method of making plasma-catalytic enhanced water comprising
It is yet another aspect of the present invention to provide a method of increasing plant growth or yield comprising producing a plasma-catalytic enhanced water and delivering the plasma-catalytic enhanced water to one or more plants.
These and other aspects of the Invention will be apparent from the detailed description below.
According to various embodiments of the present invention, a system and method are provided for the production of plasma-catalytic enhanced water that may be used for agricultural plant management. The system may include a water source that is fed into a plasma discharge with a gas. The gas preferably comprises nitrogen and oxygen. While in the plasma discharge, the chemical composition of the water is enhanced through plasma-catalytic effects, creating a plasma-catalytic enhanced water. The plasma-catalytic enhanced water then exits the plasma discharge and Is collected in a receiver, which stores the plasma-catalytic enhanced water, or alternatively, the water may be immediately provided for application to one or more plants through a water delivery system. The plasma-catalytic enhanced water made according to various embodiments of the present invention may be used as a feedstock on plants to stimulate growth, reduce water feed requirements, and reduce abiotic and biotic stresses in plants, such as pathogens, bacterium, fungi, and viruses. The system in some embodiments of the invention may be provided as a single mobile water processing unit comprising a water source, an air source, a plasma power supply, a plasma discharge reactor, and a water receiver/delivery system.
The systems and methods according to the present invention allow for the control and delivery of a plasma-catalytic enhanced water feedstock with ideal quantities of pH, nitrate, nitrite, hydrogen peroxide, peroxynitrate, and other hydrogen, oxygen and nitrogen containing compounds, ions, radicals and active species. When oxygen and nitrogen containing gases are supplied to a plasma generator according to the present invention, the plasma discharge generates high concentrations of reactive oxygen and nitrogen species, charged chemical constituents, and UV radiation. The reactive species serve to defend against pathogens, bacterium, fungi, and viruses present in the water. In addition, reactive oxygen and nitrogen species present in the plasma-catalytic enhanced water produced according to the present invention may also reduce pathogen load in the soil when delivered to the root system of plants.
Direct delivery of nitrite and nitrate to a plant root system may obviate the need to regulate soil microflora and reduce the temperature requirements for plant germination and growth. Bacteria are needed to be present in soil to digest ammonia-based fertilizers and produce the nitrate required by the plant. For this reason, soil temperature needs to be appropriate for bacteria survival and growth (˜50 F). Because nitrate may be produced and incorporated in the plasma-catalytic enhanced water made according to the present invention, the nitrate may be delivered directly into the soil, thereby eliminating or reducing the need for bacteria and reducing the temperature requirements for plant germination and growth. The active ionic species provided by plasma treatment will also impact surface interactions with soil, potentially improving water retention between liquid-particle surfaces.
The water processing systems according to various embodiments of the present invention may be provided as a point-of-use system to process onsite water into enhanced water having antimicrobial activity that is better retained by plants and increase growth. The systems and methods according to the present invention may reduce and potentially eliminate the need for fertilizers and improve the rate of germination and nutrient up-take by plant seeds and developing plants. Furthermore, the use of the plasma-catalytic enhanced water made using the systems and methods of the present invention may result in faster germination, improved growth rate, and improved yields. The chemical composition of the plasma-catalytic enhanced water according to various embodiments of the present invention may be obtained by varying plasma parameters such as plasma power, water flow rate, plasma gas flow rate and plasma gas composition, which may provide plasma-catalytic enhanced water with properties suitable for a variety of different applications.
The systems and methods according to the various embodiments of the present invention utilize a plasma discharge to produce plasma-catalytic enhanced water. An ionized gas is referred to as plasma when its electron density is balanced by that of positive ions and it contains a sufficient amount of electrically charged particles to affect its electrical properties and behavior. Plasma discharges exist in a wide range of conditions, and their particular properties depend on a variety of parameters including pressure, temperature, and density.
Generally, plasma is separated into two main temperature regimes, non-thermal and thermal, either of which may be utilized in the systems of the present invention. Plasma can be separated into multiple regimes as defined by the difference in electron and ion temperatures and the balancing of energy transport processes. The measure of the kinetic energy of a gas constituent, and thereby defining the temperature of the gas and/or its constituents, is the summation of translational, rotational, vibrational and electronic energy. When the mean kinetic energy (temperature) of the ions is equal to the mean kinetic energy (temperature) of the electrons in the plasma, the plasma is said to be in Thermal Equilibrium; if the relationship is valid only on a small scale and not globally, the plasma can be considered to be in Local Thermal Equilibrium. In the case where the mean electron kinetic energy is significantly higher than that possessed by the ions, the plasma is said to be a non-equilibrium plasma. The embodiments of the present invention may form a plasma that can by described by any of these regimes or any combination of plasma regimes. Such energies are achieved via electron-electron collisions and electron collisions with heavy particles, which result in Ionization of the heavy particles. Depending on the frequency of collisions, the energy (and hence temperature) of plasma components (electrons and heavy particles) can be different. As a result, the plasma can exist in a non-equilibrium state.
In non-thermal plasma, electron temperature is highest (usually 10,000K or 1 eV); however, rotational excitation temperature, ion temperature, and heavy particle temperature, or the bulk gas temperature, are all quite low (room temperature). Under such conditions, high energy electrons lead to the formation of active chemical species and radicals, such as atomic oxygen (O) and hydroxyls (OH), and electronically excited oxygen (1O2). It is these plasma-generated radicals and Ions that behave like catalysts, and participate in chain reactions that promote or accelerate reaction pathways. Thermal plasma, however, is often characterized by temperature equilibrium, where the temperature of all energy levels and components are nearly equal. In thermal plasma, the joule heating effect results in high gas temperature. In thermal plasmas, energy is used to heat the entire gas, and temperatures often range from 10,000-100,000K (10-100 electron volts (eV)).
Various types of plasma discharges may be incorporated in the water processing systems according to the present invention. The types of plasma discharges include, but are not limited to, glow discharges, corona discharges, Dielectric Barrier Discharges, arc discharges, gliding arc discharges, microwave discharges, and radio-frequency discharges.
The glow discharge is the most well-known type of non-thermal plasma known to those of skill in the art. It can be described as a self-sustained continuous DC discharge with a cold cathode, which emits electrons as a result of secondary emission. Glow discharge has distinct features such as: a cathode layer (a positive charge space with strong electric field), a positive column (a quasi-neutral plasma with low electric field located between the cathode and anode), and an anode layer (a negative charge space with slightly elevated electric field). A normal glow discharge operates in a current regime of 10−4-0.1 A. Any increase in current above this regime will result in a transition to an abnormal glow discharge. Increasing current further (1 A) will result in a transition to an arc discharge.
The corona discharge is also very well known, manmade and naturally occurring plasma discharge. It can be described as a weakly luminous, non-uniform discharge, which appears at atmospheric pressure near sharp points, edges, and along thin wires. Strong electric field and Ionization along with some luminosity are located near one electrode. The charged particles are then carried by weak electric fields from one electrode to another. Corona discharges can be both positive and negative. Another form of corona discharge is the pulsed corona discharge. Continuous corona discharges are limited by low current and power, which results in more application for materials and gas streams, such as environmental and fuel conversion applications. It is possible to increase power in a corona discharge without transition to the spark regime by using pulse-periodic voltage. Pulsed corona can be relatively powerful (10 kW) and quite luminous. The most typical corona configuration (both pulsed and continuous) is created around a thin wire, which maximizes the active discharge volume. For corona discharges, a non-homogeneous electric field is used to stabilize the discharge via the buildup of space charge around a corona wire or point.
Dielectric Barrier Discharge (DBD) is similar to pulsed corona, in that its development was a result of trying to find a solution for avoiding spark formation. In the case of DBD, a dielectric barrier is used to stop current and prevent spark formation. The DBD electrode gap includes one or more dielectric layers, which are located in the current path. Gap distance is typically in the range of 0.1 mm to several centimeters. Some of the dielectric materials that can be used are glass, quartz, and ceramic.
The arc discharge is an ionized channel of gas in what is normally non-conducting medium such as gas. Arc discharges have been used for many industrial and commercial applications including metallurgy, waste disposal, lighting applications, and Ignition systems in vehicles. They are high-current (30 A or above), low-voltage (10-100V) discharges, which have very high gas temperatures (10,000 degrees K and above or 10 eV and above). The high gas temperature is due to the high degree of joule heating from the discharge current. Their initial high temperature also contributes to sustaining high current by influencing the mechanism by which electrons are supplied to the discharge, namely the thermionic and field emission mechanism. Thermionic emission is electron emission from a high temperature metal surface due to the high thermal energy of electrons in the metal. For this process to occur, a combination of high metal surface temperature must be coupled with sufficient external electric field in the cathode vicinity. This permits a large number of electrons to escape the metal surface and provides a high flux of current into the discharge. The high temperature of arc discharges can lead to problems such as evaporation and electrode erosion. These problems can be partially mitigated by actively cooling the electrodes. Unfortunately, arc discharges have the significant drawback of high operational electrical energy cost.
A conventional gliding discharge, traditionally called gliding arc (GA) is an auto-oscillating periodic phenomenon that develops between at least two diverging electrodes submerged in a laminar or turbulent gas flow. First, the discharge self-initiates at the upstream narrowest gap in what is termed the breakdown stage. Then, the discharge forms a plasma column connecting the electrodes of opposite polarity, which is termed the equilibrium stage. This column is dragged by the gas flow towards the diverging downstream section. The discharge length grows with the increase of inter-electrode distance until it reaches a maximum possible value, usually determined by the power supply limit. The non-equilibrium stage starts when the length of the gliding arc exceeds this critical value. Heat losses from the plasma column begin to exceed the energy supplied by the power source, and it is not possible for the discharge to remain in equilibrium. At this point, the plasma rapidly cools and decays. After this point, the discharge extinguishes and momentarily reignites itself at the minimum distance between the electrodes, starting a new cycle.
Microwave discharges have the great advantage of being capable of operation without electrodes. Instead of utilizing a potential difference between electrodes, a microwave discharge is sustained by a high frequency electromagnetic field. Operation without electrodes is often preferred for high temperature applications because it may eliminate the need for complicated electrode cooling. Initiating high frequency plasmas, however, is more challenging than traditional DC plasmas because microwave requires more complex, expensive power supplies along with additional components such as a frequency generator (magnetron head), a circulator, a tuner, a directional coupler, a waveguide. In addition, the plasma must be coupled as a load in the power circuit. In general, this coupling is accomplished via waveguides, where a quartz tube is inserted into the waveguide. The plasma is ignited and confined to the quartz tube. Microwave discharges may exist as both thermal and non-thermal discharges. Thermal microwave plasma discharges operate at atmospheric pressure, while non-thermal microwave operates at low pressure. The thermal properties of microwave plasma will generally increase as pressure is increased.
Radio frequency (RF) discharges share many similar properties with microwave discharges. RF discharges operate without electrodes (only in the 0.1 to 100 MHz region) and can exist in both thermal and non-thermal regimes that are pressure dependent. Thermal plasma generation is provided via inductively coupled plasma (“ICP”) at atmospheric pressure. In this case, high frequency current passes through a solenoid coil, providing a magnetic field. This allows for the formation of a vortex electric field, which sustains the RF ICP discharge. Again, expensive power supplies and additional components may be required, and the plasma should be coupled as a load with an RF generator. Effectiveness of coupling the electromagnetic field to the plasma discharge is desirable because the plasma is sustained by the energy absorbed by the field. Poor coupling will result in low efficiency of the power supply. At low pressures, RF plasma can exist in a strongly non-equilibrium regime. In this regime, the capacitively coupled plasma (CCP) can be utilized. RF CCP operates with higher electric fields. As a result, RF CCP discharges are more non-thermal than ICP and can generate non-thermal plasma at moderate to high pressures.
Referring now to
The water source included in various embodiments of the present invention may be one of any number of water sources including, but not limited to, tap water, spring water, deionized, or distilled water. Water sources commonly used in the agriculture industry are the preferred sources of water for the system and methods according to the present invention. Depending on the application and location, delivery of the water may require extra equipment to transmit the water to the system or from the system. A water pump may provide the pressure necessary to pump the water into the plasma discharge. As understood by one of skill in the art, the pump should be scaled to meet the requirements associated with the volume of water needed for a given application.
The gas used to form the plasma discharge in the system according to the present invention includes oxygen and nitrogen. Air is the preferred gas for discharge formation. The gas may be provided to the system via multiple sources using equipment known to those of skill in the art, such as an air compressor, for example. A compressor may provide the condensed gas flow necessary to create the plasma discharge. Once the discharge is established, the compressed gas provides the supply of nitrogen and oxygen that will react to form a variety of Ions, radicals, compounds, and excited species. The compressor may be used to control flow rate to provide an optimal balance of chemical reactions and plasma discharge.
In order to provide the optimal balance of chemical reactions with the plasma discharge, the systems according to various embodiments of the present invention may also include an additive addition stage. The additives may include, but are not limited to, any noble gas, oxygen, nitrogen, gaseous H2O, fertilizer based gases containing potassium-, nitrogen-, or phosphorus-containing compounds, liquid H2O, H2O2 and fertilizer based liquids containing potassium-, nitrogen-, or phosphorus-containing compounds, and solids such as fertilizer based containing potassium-, nitrogen-, or phosphorus-containing compounds. These additives may be added, for example, before the plasma discharge as additives to the Input gas or additives to the Input water, directly in the plasma discharge region, directly in the post plasma discharge region, or directly to the produced water. The ratio of the input air and water to the additives may be modified depending on the desired plasma-chemical reactions, as well as the type and amount of compounds in the enhanced water composition, thereby allowing a user to tailor the system for a specific application.
In order to initiate, maintain, and control a plasma discharge, a plasma power supply is provided in the system according to the present invention. The plasma power supply provides the breakdown voltage needed to initiate a plasma discharge. Furthermore, the plasma power supply may regulate the current or power of the discharge, which permits stable operation at the settings for a particular discharge. Power supplies are unique to the discharge that they are sustaining. The types of power supplies that may be incorporated in the system of the present invention include, but are not limited to, line connected, reactance modulated supplies, any switching power supply, including both hard and soft switched schemes. The embodiments of the present invention may also incorporate any of the aforementioned topologies in combination with or without rectification. As explained above, the plasma discharge may be one of any number of discharges including, but not limited to, spark, arc, transferred arc, corona, DBD, gliding arc, microwave, radio-frequency, and glow discharge. A preferred plasma power supply should be capable of controlling the output current during operation. This can be accomplished with line reactors, resonant power supplies or PWM (Pulse Width Modulation) techniques, such as phase-shift, resonant, or hard switched modulators. If the supply current is not controlled through resonance, the power supply should use a defined reactance in either the primary or secondary circuit. The preferred embodiment utilizes a hard switched H-bridge, PWM topology. The power supply must also supply sufficient voltage to initiate the plasma. This can be accomplished by a pulsed, high-voltage power supply that is diode “ORed” into the circuit, or by means of resonant charging. In the preferred embodiment, resonant charging is used to initiate the plasma.
The topology of the power supply is best understood as a constant current source as the plasma voltage is a dependent effect of many other inputs. Preferably, this supply should be capable of producing variable output current so that the supply can be matched to the operational demands of different arrangements of feedstock input (working gas, gas volume, aerosol droplet size, the chemical composition of feedstock, etc.) and plasma chemistry products. The supply also must have sufficient voltage to initiate plasmas in all desired reactor geometries and the capability to control the current so that thermal equilibrium plasma generation is minimized. In a preferred embodiment, a plasma power supply will produce up to 15 kV initiation pulses, more preferably 6 to 10 kV, and be controllable up to 15 A, more preferably 2 to 10 A, and produce current with better than 10% regulation. The output may be pulsating DC, steady-state DC, or AC, preferably steady-state DC.
In a preferred embodiment of the present invention, the water processing system comprises a hybrid plasma discharge. The hybrid plasma discharge may include two simultaneous plasma discharges, such as a gliding arc discharge and a corona discharge, which provide optimal conditions for production of plasma-catalytic enhanced water for the agriculture industry. For agricultural applications, the plasma discharge should cause the following chemical reactions:
It has been found that the above chemical reactions may be easily induced by hybridizing two different plasma discharges. While not wishing to be bound to theory, it is believed that different plasma discharges are more efficient at stimulating specific plasma-chemical reactions. In the case of producing enhanced water for agricultural applications, this hybridization takes the form of one discharge optimized for production of NO and NOx and another discharge optimized for the production of ozone, hydroxyl, and peroxynitrate. While these discharges could take many forms, the preferred plasma discharges included in the hybrid plasma discharge are (1) a gliding arc discharge, and (2) a corona discharge. A schematic of the preferred design for reactor providing the hybrid plasma discharge is provided in
As explained above, the conventional gliding arc starts as an electrical breakdown in a narrow gap between two diverging electrodes in a gas flow. When the electric field in this gap reaches approximately 3 kV/mm in air, the air in the gap becomes ionized and is said to have “broken down.” The output voltage of the power supply causes a rapid increase plasma current until the plasma enters a negative resistance regime. In this regime, increasing current will cause the plasma voltage to decrease. If the gas flow is strong enough, it forces the arc to move along the diverging electrodes and to elongate. By forcing the arc to elongate, the arc is cooled through conductive and convective mechanisms and through black body radiation as the surface area increases. Cooling the arc causes the plasma voltage to rise. If the power supply is configured for constant current, the output current of the power supply rises to maintain the current and thereby allows the plasma voltage to increase. If the power supply is configured for constant arc power, the current is increased by increasing the output voltage. Maximum power is delivered at the point where the product of the current and voltage is maximized. The plasma will be extinguished when the power supply can no longer supply enough current or power to maintain the plasma channel gas temperature and thereby its conductivity. At that point, the power supply output voltage must rapidly rise to the breakdown voltage of the initial gap, thus restarting the cycle.
As a result of the above mentioned qualities, the gliding arc exists in both thermal and non-thermal regimes, which contribute to unique plasma chemistry and is ideal for providing NO and NOx in the hybrid plasma discharge. For example, the gliding arc may provide NO and NOx through both thermal and non-thermal pathways as follows:
N2+O2→2NO
N2+e−→2N+e−,
O2+e−→2O+e−,
N+O→NO.
This formation occurs in the higher temperature zone of the hybrid discharge (white dashed line in
Gliding arc discharges may also produce NO3−, NO2−, OH−, O3, H2O2, peroxynitrate, and other oxygen and nitrogen containing radicals and active species, when a discharge utilizes nitrogen, oxygen and water as media. In the embodiment in
Corona discharges have low specific power and concomitantly low bulk gas temperatures. High concentrations of ozone in a corona discharge may be achieved with increased residence time of gas in the discharge zone. A large pulsed corona volume also leads to effective convective gas mixing in the plasma discharge and high heat transfer to the walls of the plasma discharge chamber. As a result, the system does not overheat, and the stability of the synthesized ozone is preserved. Therefore, the corona discharge may comprise the primary ozone generating portion of the hybrid plasma discharge, while also contributing hydroxyl, and other oxygen and nitrogen containing radicals and active species. For example, the corona discharge can exist in the low temperature zone of the hybrid plasma discharge (light-gray dotted line in
O+O2+M→O3+M,
H2O+e−→H+OH*+2e−
In the embodiment in
2NO2+O3→N2O5+O2
N2O5+H2O→2HNO3
NO+OH+M→HNO2+M
NO2+OH+M→HNO3+M
The embodiment also includes optional air and/or water addition through nozzle 4, which can stimulate further plasma-chemical reactions. The HV and ground portions of the system may be separated with dielectrics.
The plasma reactor according to various embodiments of the present invention may include electrodes may from one or more of a variety of metals. Preferably, the metal or metal alloy is selected, so that it is suitable for contact with water and may provide material specific benefits depending the Intended application. Specific examples include, but are not limited to:
In order to inject water in the plasma discharge, the systems according to embodiments of the present invention may utilize a nozzle. The nozzle is preferably an atomizing nozzle to supply the water in the form of water droplets, which exhibit very high surface area, into the plasma reactor. Types of nozzles may include, but are not limited to, an ultrasonic atomizer, Plain-orifice nozzle, Shaped-orifice nozzle, Surface-impingement single-fluid nozzle, Pressure-swirl single-fluid spray nozzle, Compound nozzle, Internal-mix two-fluid nozzles, and External-mix two-fluid nozzles. The nozzle may be selected based a number of variable including, but not limited to, the scale of water production and the desired water surface area in the plasma zones. The nozzle should also be configured to direct the spray through the plasma zone of the reactor. If the spray angle of the nozzle is too large, the water may be directed towards the side walls of the electrodes in the plasma reactor. This will allow the water to avoid treatment by cascading along the Inner surfaces of the reactor and around the plasma zone. It is preferred that a spray angle is selected such that at least half of the flow rate of water passes through the plasma zone, more preferably substantially all of the water should pass through the plasma zone of the reactor.
In various embodiments of the present invention, water and/or gas may be injected tangentially, axially, or both tangentially and axially in the plasma reactor, relative to the orientation of the HV and/or ground electrode. In the preferred embodiment of the invention, the water and gas may be injected tangentially, axially or both tangentially and axially to the gliding arc, corona, or to both the gliding arc and corona in any order or iteration. Water is preferably introduced in a manner that maximizes surface area contact with the plasma discharge and the gas, preferably air, is preferably introduced in a manner that maximizes air velocity.
In one embodiment, the water may be introduced axially through a nozzle and treated by corona discharge, followed by treatment in the gliding arc discharge where air may be injected tangentially to form a vortex, followed by exhausting of the treated products out of the plasma reactor. In another embodiment, the water may be introduced axially through a nozzle, treated by gliding arc where air is injected tangentially to form a vortex, followed by treatment of the products by corona discharge, followed by exhausting of the treated products out of the plasma reactor. In yet another embodiment, air and water may be injected tangentially into the gliding arc discharge, followed by treatment of the products by corona discharge, followed by exhausting of the final products out of the plasma reactor. In yet another embodiment, air and water may be injected tangentially, an additional air supply may be injected axially, and the air and water may be simultaneously treated by gliding arc discharge and gliding corona discharge followed by exhausting of the final products out of the plasma reactor.
A system according to the present invention may also be provided in the form of a mobile plasma-catalytic enhanced water production unit. An illustration and photograph are provided in
The plasma-catalytic enhanced water generated using the systems and methods of the present invention preferably have a chemical composition that provides the ideal soil pH and nutrient composition for plant water feedstock. Soil pH plays a crucial role in the development and yield of plants. For example, a pH of 6.5 is recommended for most home gardens because most plants thrive in a pH of about 6.0 to 7.0 (slightly acidic to neutral) range. Some plants (blueberries, azaleas) prefer more strongly acidic soil, while a few plants (ferns, asparagus) do best in soil that is neutral to slightly alkaline. Examples of plant pH preferences include:
The degree of treatment using the systems of according to the present invention may be achieved through controlling the enthalpy. Specific energy input (SEI), also known as enthalpy, characterizes the relative energy into a media. In this case, the media is a flow of water and air and can be calculated:
In this equation, P is the power of the plasma discharge [kW, kilowatts], which is provided by the plasma power supply. Furthermore, Q is the flow rate of the media. For the present invention, Q will be the flow rate of air, Qa, and the flow rate of water, Qw, and is expressed as kWh/m3 and kWh/gallon, respectively. Enthalpy of the plasma stream is preferably maintained at the lowest level necessary to obtain a desired composition. If the production of plasma-catalytic enhanced water must be scaled up, the plasma stream enthalpy and water flow rate can be increased proportionally to maintain the same ratios and consistent enhanced water composition.
Nitrates and nitrites are beneficial for plant growth. The concentration of nitrates and nitrites in the plasma-catalytic enhanced water may be controlled by the systems according to the present invention by modifying the composition of the reactants (water and gas) and the enthalpy of the system. Addition of water to the plasma gas may also result in the generation of reactive oxygen species, such as, but not limited to, hydroxyl radicals and hydrogen peroxide. These species are unstable and will exist in water for a relatively short time. Water containing these reactive oxygen species will maintain antimicrobial, antifungal, and antiviral properties while these species remain active. The concentration of these species may also be controlled by changing input composition and enthalpy of the system.
For example, if the plasma-catalytic enhanced water contains an unacceptably high concentration of nitrates and nitrites, the gas delivered to generate the plasma may be modified by increasing the nitrogen to oxygen ratio and/or treated using a more thermal discharge. If the plasma-catalytic enhanced water contains an unacceptably high concentration of H2O2 or dissolved ozone and Insufficient nitrates and nitrites, the composition of the gas input may be modified by lowering the nitrogen to oxygen ratio and/or treated with a less thermal discharge. In certain embodiments of the present invention, a single system may include both a more thermal plasma discharge and a less thermal plasma discharge to both balance and further enhance the water composition.
Once the plasma-catalytic enhanced water is produced, it may be stored or provided to an immediate delivery system. If the application of Interest requires only long lived nitrogen containing species, the plasma-catalytic enhanced water may be stored for extended durations and used when desired. If short lived reactive species are desired, like H2O2 or dissolved ozone, the plasma-catalytic enhanced water should be immediately fed to a delivery system for application. In either case, the product should be distributed to agricultural products as necessary to achieve the desired product growth and yield.
In order that the invention may be more fully understood, the following Examples are provided by way of Illustration only.
A brief investigation was conducted to determine the quantity of plasma generated species in water over time. A gliding arc plasma discharge was used to treat 30 mL/min of water with an air flow rate of about 75 L/min at an average current of 200 mA, a voltage of 1.5 kV, and 300 W. The plasma-catalytic enhanced water was tested immediately and subsequent hours for the following parameters:
TN: Total Nitrogen (N) in water
TP: Total Phosphorus (P) in water
TK: Total Potassium (K) in water
H2O2: Hydrogen Peroxide
NO3−: Nitrate
NO2−: Nitrite
TH: Calcium & Magnesium Carbonates
O3: Ozone
pH
Alkalinity
1. N—P—K
Nitrogen, Phosphorus, and Potassium are the three primary nutrients found in fertilizers. They are the soil macronutrients and fertilizer companies attempt to balance and control them. Each plant prefers a specific balance of nitrogen (N), phosphorus (P), and potassium (K), and depending on the region, the nutrients will already be available, sometimes in excess, in that region's soil.
2. Total Nitrogen
The metric “total nitrogen” is used commonly in agricultural and wastewater industries to account for nitrogen compounds that are likely to be found. It accounts for the sum of ammonia-N, organic N, nitrate and nitrite. For plants, nitrogen is important for growth. It promotes lengthening of trunks and increases foliage and fruits. It is most commonly absorbed by plants in the form of nitrate NO3−. Excess nitrogen can weaken a plant's structure creating an unbalanced relationship between the green parts and the wooden parts. Plants also become less resistant to diseases when soil contains too much nitrogen.
3. Total Phosphorus
Phosphorus is important for energy regulation in plant cells, which will affect the quality of seeds and the formation of buds and roots. Without enough phosphorus, plants cannot grow as fast and will produce less and/or smaller fruits. Phosphorus is taken up by plants quite slowly as it is commonly found in an organic form and must be decomposed to be useful to plants. As soil pH decreases, phosphorus will be less available to plants because it will tend to react with metals like aluminum and iron in the soil.
4. Total Potassium
Potassium affects plant quality and is often absorbed at an increased rate in the early stages of growth. It is also important for regulating energy as it is required for photosynthesis, water regulation, etc. Potassium requirements, however, vary heavily on the plant. Optimizing potassium availability is also soil-type dependent. Furthermore, potassium optimization of potassium may be difficult because it may displace other nutrients in the soil. For example, K2O may be prevalent in warmer, slightly acidic soil, but may cause the displacement of other ions that are likely to be present like calcium or aluminum.
5. pH and Alkalinity
The pH is a measure of the presence of the hydrogen ion (H+). Each plant has a unique preference of pH range, as explained above, in order to increase its growth potential. In the area of agriculture, pH is useful as an indicator for what nutrients and microorganisms are available in the soil environment. Manipulating the pH can affect these factors. For plants, a pH of 6.5-7 is considered neutral and optimal for most crops; a pH of 6 is slightly acidic; a pH of 5 is strongly acidic. Alkalinity is the measure of the capacity to neutralize acids. The plasma-catalytic enhanced water made according to the present invention is acidic, and therefore, has low alkalinity and will not neutralize other acids.
6. Nitrate
Nitrate is a polyatomic ion with the molecular formula NO3− and a molecular mass of 62.0049 g/mol. The air generated plasma will produce high concentrations of NO3− that will increase over time, as other compounds in the plasma-catalytic enhanced water decomposes.
7. Nitrite
Nitrite is an ion, which has the chemical formula NO2−. The air generated plasma will produce some NO2−, however it is a short-lived species that will decrease over time.
8. Hydrogen Peroxide
Hydrogen peroxide has the formula H2O2. It is used by gardeners. Rainwater naturally contains small quantities of it. Its use is gaining popularity among marijuana growers. There is evidence for use of H2O2 for soil remediation. H2O2 oxidizes organic matter and is a primary mechanism to control infections, fungal growth, etc. The air generated plasma will produce some hydrogen peroxide in water, but it is one of the short-lived species. It most likely reacts with nitrite to form nitrate and nitric acid over time.
9. Total Hardness
Total hardness measures the presence of Ca2+ as CaCO3.
Table 1 provides the concentrations of plasma generated species in the enhanced water obtained from a gliding arc discharge, as well as other parameters, over a 36 hour period.
Several runs were performed varying water and air flow rate, current, and voltage for a system using a gliding arc discharge. The pH and nitrate concentration in the plasma-catalytic enhanced water was immediately tested during each run.
From the data used to generate
A power analysis of a system including a gliding arc discharge according to an embodiment of the present invention was performed. An oscilloscope was used to monitor the current and voltage of the plasma discharge for two settings. In the first setting, a 10 ml/min water and 24 L/mln air flow rate was used with an average power input of 222 W. In the second setting, a 24 ml/min water and 10 L/min air flow rate was used with an average power input of 1.22 kW. The current and volts over a 50 ms period using the first setting was recorded, and the data set plotted in
High power deposition indicates that an arc is struck at a relatively high voltage level, and the resulting high current creates a very low resistance current channel through gas. When the power supply output capacitance voltage has been drained and the arc can no longer be sustained, the plasma is extinguished and the power supply output begins charging to the breakdown level. All of the energy has been expended on vaporizing electrodes and heating gas. In
Arc formation takes place in tens of nanoseconds. There is no physical means to throttle this process. The current will rise to the limit allowed by system inductance and plasma resistance, therefore the difference in behavior between
Furthermore, the change in pH scales with air velocity. Increasing velocity would have the tendency to lower the pressure in the plasma discharge. At lower pressures, it should be easier to ignite a plasma, but the data shows increasing rather than decreasing voltage. However, at the higher air velocities, the water transitions from droplets to an aerosol, which is the desired operational mode. This data suggests that when designing a plasma power supply and discharge reactor, total power input is less critical than water surface area and maximizing the interaction between the plasma discharge and water surface.
An image comparing the Cannabis Sativa grown utilizing plasma catalytic enhanced water and without utilizing plasma catalytic enhanced water is provided in
While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the Invention.
The present application claims priority to U.S. Provisional Application 62/063,191 filed on Oct. 13, 2014, the entire contents of which are incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62063191 | Oct 2014 | US |
