Modular system for producing ammonium hydroxide of variable concentration on-site

Abstract

A system and method for generating aqueous ammonia of variable concentration from water and any existing anhydrous ammonia source. The system is modular and safe, can be powered by almost any electrical source, can produce varying volumes of output aqueous ammonia without a prohibitive loss of efficiency, and can produce varying concentrations of output solution.

Description

MODULAR SYSTEM FOR PRODUCING AMMONIUM HYDROXIDE OF VARIABLE CONCENTRATION ONSITECross Reference to Related Applications

[0001] This application claims priority and the benefit of US Provisional Patent Application Serial No. 63 / 564,692, entitled "MODULAR SYSTEM FOR PRODUCING AMMONIUM HYDROXIDE OF VARIABLE CONCENTRATION ON-SITE" filed on March 13, 2024, the disclosure of which is incorporated herein by reference in its entirety.Background

[0002] The field of this disclosure is the production of ammonium hydroxide (aqueous ammonia).

[0003] Ammonia is an important component of many fertilizers (among its many uses in commercial, industrial and other applications). Anhydrous ammonia (NH3) has many applications, but cannot be used in greenhouses. There are also general safety concerns with the production, transportation and on-site storage of NH3, as it is a toxic substance. Aqueous ammonia is therefore preferred to NH3in some applications.

[0004] The production of aqueous ammonia currently requires a large facility, producing large quantities of aqueous ammonia. These facilities, owing to their size, require large-scale water supplies and energy sources (typically natural gas). The output solution must then be transported and stored near the place of use, and the large-scale system doesn't allow for straightforward and rapid changes in the concentration of the output ammonia. A system which could produce aqueous ammonia in-situ, with the ability to easily and rapidly change the concentration of the output aqueous ammonia (effectively, changing the concentration of nitrogen content in the solution) would allow a production system to be situated near where the solution is needed (without needing the solution to be transported), and would permit the output of the system to be tailored to changing needs.

[0005] There is a desire for a system which can produce variable concentrations of ammonium hydroxide on-site.Summary

[0006] A system and method for generating aqueous ammonia of variable concentration from water and any existing anhydrous ammonia source. The system is modular and safe, can be powered by almost any electrical source, can produce varying volumes of output aqueous ammonia without a prohibitive loss of efficiency, and can produce varying concentrations of output solution.Brief Description of the Drawings

[0007] FIG. 1 is a piping and instrumentation diagram (P&ID) for an exemplary modular system for producing ammonium hydroxide.

[0008] FIG. 2A is a perspective view of an exemplary modular system for producing ammonium hydroxide.

[0009] FIG. 2B is a top view of an exemplary modular system for producing ammonium hydroxide.

[0010] FIG. 2C is a front view of an exemplary modular system for producing ammonium hydroxide.

[0011] FIG. 2D is a right side view of an exemplary modular system for producing ammonium hydroxide.

[0012] FIG. 3 is a datasheet for an exemplary diffuser used to diffuse the anhydrous ammonia in the reactor.Detailed Description

[0013] It is the object of this disclosure to provide a system and method for the generation of ammonium hydroxide from anhydrous ammonia and water. The system essentially implements a chemical reactor to produce ammonium hydroxide from anhydrous ammonia and water according to the reaction NH3+ H2O NH4OH.

[0014] The output solution's concentration of ammonia may be varied from as low as 0.5% concentration (typical for household cleaning solutions) up to 30%. The system can rapidly change its output concentration, stabilizing at almost any new concentration in under 15 minutes. The variability of the output is important, as different crops and methods of fertilizing may require different concentrations of aqueous ammonia.

[0015] By using much less electrical power than large-scale aqueous ammonia plants (lending it to using solar or other green electrical generation systems), taking only NH3, N2and H2O as its inputs,recycling its generated heat, and providing aqueous ammonia at the point of use (i.e. not requiring long- haul transportation), this system is a far more environmentally friendly aqueous ammonia generation system than any other, and therefore may be considered to be producing "green aqueous ammonia". Note that N2is needed for purging the system, but is not an input to the desired chemical reaction.

[0016] The embodiment shown in the drawings is one size, and the sizing and layout of this embodiment should not be considered limiting on the invention itself. Larger embodiments are also contemplated, including systems that produce 1500 kg or more per day of aqueous ammonia. Intermediate system sizings are also contemplated. Those skilled in the art will understand from this disclosure how to create these other embodiments.

[0017] The exemplary system discussed here may be conceptualized as consisting of several interconnected subsystems: sources for the required chemical components, a power source, the main reaction system, a cooling system for the main reaction, a heating system for the anhydrous ammonia, a feedback control system to vary the output solution concentration, a cleaning / purging system to remove constituents and solution from the various elements of these systems, storage of the reaction's output solution, and an overall control system. Each of these is discussed below.

[0018] Referring to FIG. 1, these various subsystems and their interconnections may be seen. FIG. 1 is a piping and instrumentation diagram (P&ID) for an exemplary system, but other setups, components and configurations may be envisioned. Many control, regulation and backpressure valves are shown on FIG. 1 for use as control and safety components; these are included as best-practice safety and control measures, but may be substituted for other safety or control systems, or omitted if safety codes and practices allow. The implementation of safety mechanisms is known to those skilled in the art. It will also be understood that while a centralized control and measurement system is shown here, it may be feasible to implement this system with only partially automated control, with some of the control and measurement components implemented as independent valves or gauges - once again, those skilled in the art will understand which elements may be thus substituted. Finally, those skilled in the art will understand when one valve type (such as a ball valve) may be substituted for another type (such as a needle valve), and what the functionality, safety and system longevity ramifications of such a change might be.

[0019] In FIG. 1, 100-series components relate to the anhydrous ammonia lines, 200-series components relate to the nitrogen (N2) purge lines, 300-series components relate to water lines, 400- series components relate to intermediate NH4OH product mix lines, 500-series components relate tocoolant lines, 600-series components relate to mix recycling lines, and 700-series components relate to the output NH4OH aqueous ammonia solution.Chemical Sources

[0020] The chemical sources are shown on the left. These required chemicals and compounds are nitrogen (N2) 800, water (H2O) 801 and anhydrous ammonia (NH3) 802. Note that N2is a system input, but is used for purging the system after use, or in the case of emergency; it is not an input to the system contributing to the desired chemical reaction.

[0021] Nitrogen gas (N2) is used to purge and clean the overall system. Preferably UHP (Ultra-High Purity) nitrogen (typically at a purity of 99.999% pure) is used to purge and clean the system, as a safety measure (particularly as anhydrous ammonia is toxic). Preferably, the nitrogen source is pressurized at 1.5 to 2 bar, just above atmospheric pressure. As shown in FIG. 1, the nitrogen first passes through a backpressure valve 200, and is then piped to the output solution storage tank 700, with a separate branch feeding to the anhydrous ammonia source line as well as to the reactor 350. Each of these branches has control valves 210, 202 to only permit N2to flow when needed, as well as measurement gauges.

[0022] Water is used to dilute the anhydrous ammonia and create the aqueous ammonia solution. Preferably deionized or softened water is used, to reduce impurity build-up within the pipes of the system, but tap water may also be used. The water source 801 replenishes the water stored in the water storage tank 300. From the tank, a pump 803 pumps the water to the reactor 350. A supply feedback line, through valve 302, allows the water to return to the tank if necessary. Another valve, 308, allows the water to flow directly to the output tank.

[0023] Anhydrous ammonia is used to produce the aqueous ammonia, by diluting it with water in the reactor. The anhydrous ammonia is stored in a pressurized tank 802, preferably at 5 - 7 bar pressure. When the anhydrous ammonia leaves the tank 802 (controlled by valve 101), the drop in pressure, to preferably 1 bar pressure, causes the ammonia to cool rapidly. To prevent the anhydrous ammonia from freezing, it must pass through a heating element which, in this exemplary implementation, is a heat exchanger 120, but which may be any kind of heating element or subsystem which prevents the anhydrous ammonia from freezing. After passing through another control valve 109 and a bleeding valve 110, the anhydrous ammonia enters the reactor 350 and passes into the diffusor 804 inside the reactor, from where it is dispersed within the reactor. The output of the reactor passes through heat exchanger 430 and into output solution storage tank 700. The main system output 805 is from where the aqueous ammonia may be obtained.

[0024] The anhydrous ammonia may be produced off-site and brought to the site in a tank, or may be produced on-site. The presently disclosed system's anhydrous ammonia input tank 802 may be substituted for an input directly or indirectly connected to the output of the anhydrous ammonia generation system disclosed in US20220388855A1, the disclosure of which is incorporated herein by reference in its entirety.Power Source

[0025] The power source for the system may be any electrical source capable of supplying the power needs of the system, such as solar, geothermal, wind or grid power. The total electrical power needed by the system depends on the final embodiment, but in most cases will be between 5 kW and 6kW. The power source is used to power pumps, gauges, measurement equipment, valves, the control system, and any other aspect of the system which requires electrical power. The reaction itself does not require electrical power to occur.The Reactor

[0026] The reactor 350 is preferably a tank which allows for passive or active mixing of the water and anhydrous ammonia. Preferably, it comprises at least one nozzle 806 for water intake, a diffusor 804 for anhydrous ammonia intake, a reaction chamber 807, a purging input line 808, a solution output line 809, a feedback input line 810, a cooling subsystem 811 and a pressure relief valve 812.

[0027] The nozzle 806 is preferably a full-cone spray nozzle. In the exemplary system, multiple nozzles 806 are indicated. These nozzles may have a 60°, 90° or some other spray angle. Preferably, the nozzles 806 are made of stainless steel, and are sized to have an optimal spray size which allows for a reasonable pump size and causes acceptable mixing. The nozzles 806 spray water into the reaction chamber 807 and connect directly to the water line entering the reactor 350. The direction of spray may be straight into the reaction chamber, or the nozzles may be angled to cause the water spray to hit the side of the reaction chamber or a diffusion element within the chamber.

[0028] The diffusor 804 for anhydrous ammonia functions to diffuse the anhydrous ammonia into the aqueous ammonia solution. An exemplary diffusor is shown in FIG 3.

[0029] The reaction chamber 807 is a container, preferably made of stainless steel, which allows the reaction to take place. Optionally, the chamber may have interior features, such as irregular or sloping walls or internal diffusion elements such as baffles, which may cause turbulence to speed the mixing of the water, anhydrous ammonia and solution already present in the reactor. Optionally, a poweredmechanical mixing mechanism may be present within the chamber to speed the mixing. Optionally the reactor may feature a separate chamber for the reacted materials.

[0030] The purging input line is an inlet for the nitrogen gas into the chamber, which gas is used to purge the system before service or reuse.

[0031] The solution output line is an outlet for the mixed aqueous ammonia solution. The solution leaves the chamber through a valve 403, and is pumped into two lines: a heating line for the anhydrous ammonia (discussed below) passing through valve 421, and the primary output line, passing through valve 404. The primary output line passes through a static mixer 420, which is needed to ensure a consistent concentration mix between the output of the reactor 350 and the return line from the heat exchanger 120, as the concentration from the reactor may be changing. Following the mixer 420, the output solution passes into the heat exchanger 430 for final cooling (discussed below), and then to the output NH4OH storage tank 700. Prior to entering the tank, the line features a sample point 431 and branches off to a feedback line (discussed below).

[0032] The reactor's feedback input line allows a controlled amount of aqueous ammonia to re-enter the reactor 350, passing through valves 600 and 603. This feedback mechanism allows the concentration of the output aqueous ammonia to be constantly and rapidly changed.

[0033] The reactor's cooling subsystem serves to cool the reactor, as the reaction of water and anhydrous ammonia is exothermic and produces considerable heat. Any effective cooling system may be used. The exemplary system shown in FIG. 1 uses glycol and an external chiller (connected to chiller input 808 and chiller output 809) to cool the reactor. The same cooling system connects to the heat exchanger 430 for the final cooling of the output aqueous ammonia solution.

[0034] Pressure breathing valve 355 maintains the pressure inside the reactor close to atmospheric pressure, preventing high pressure or vacuum during operation.

[0035] The reaction is self-limiting, and while the reactor is preferably designed to operate at a temperature of 120°C, it is unlikely that the heat from the reaction could cause this temperature to be reached.

[0036] As shown in FIG. 1, a number of meters measure aspects such as temperature and flow in the reactor, to ensure that the reaction remains controlled.Heating System for the Anhydrous Ammonia

[0037] The anhydrous ammonia is preferably stored at 5-7 bar pressure in the tank 802. Upon leaving the tank 802, the pressure drops to approximately 1 bar, causing a rapid drop in temperature in the anhydrous ammonia. Heat exchanger 120 is used to heat the anhydrous ammonia to prevent it from freezing. The heat for this thermal exchange comes from a branch line of output solution from the reactor. The hot output solution is cooled by the anhydrous ammonia, while the anhydrous ammonia is heated. The output solution is returned to the output line through static mixer 420.Output Solution Concentration Feedback Control System

[0038] The output solution feeds back into the reactor 350 after it is cooled in heat exchanger 430, in order to allow the concentration to be changed quickly.Cleaning / Purging System

[0039] Anhydrous ammonia is a toxic substance. Therefore, it is important for the system to be cleared of anhydrous ammonia for cleaning or maintenance. The nitrogen gas (N2) lines shown in FIG. 1 allow for the rapid and easy purging of the anhydrous ammonia line, the reactor and the storage tank. The N2is admitted into the various lines from supply 800 for purging through controlled valves.Output Storage

[0040] The output storage tank 700 allows for local storage of the aqueous ammonia produced by the system. A pump 710 connects the output of the tank 700 to the main system output, as well as to a feedback line which returns aqueous ammonia from the tank back into the reactor. Preferably, a pressure breathing valve 705 is present as a safety measure. Unlike anhydrous ammonia, aqueous ammonia is not corrosive for plastic, so the storage tank may be made of lower-cost materials.Control System

[0041] A control system may be used to measure, control and report on aspects of the system. In FIG. 1, an exemplary control panel 850 with human-machine interface (HMI) and programmable logic controller (PLC) is shown. A standard user interface may be used to view and modify the programming of the control system. Many measurement meters may be connected to the control system, and the control system may control many of the valves - preferably, the controlled meters and valves should be as per FIG. 1. However, it may be possible to place some of the manual gauges and valves under control systemcontrol, or to conversely make some of the controlled meters and valves manual and stand-alone. Startup and shutdown valve sequencing may be automated by the control system. The control system senses internal states and controls the amount of aqueous ammonia flowing in its feedback loops, so that the output concentration may be kept at exactly the required level.Startup

[0042] At system startup, the system is first purged with nitrogen gas to clean out any impurities. Following the purge, the system is started with only water (i.e., no anhydrous ammonia - valve 101 remains closed) until the heating, cooling, mixing and control systems are stable. At this point, aqueous ammonia from the reactor 350 is circulated until stability is reached again, and only at this point is anhydrous ammonia introduced. Once the decided concentration is reached, the solution is pumped to the storage tank 700 while new solution is being produced and recirculated in and to the reactor.Embodiment of the Invention

[0043] FIG. 2A, 2B, 2C and 2D show several views of an embodiment of the system. The system itself is designed to fit within a 10' long shipping container with dimensions of Length X Width X Height. The reactor is preferably a cylinder 6-12" in diameter and 24" in height. The components may be affixed to a frame 851 for stability. The large anhydrous ammonia cylinder 802 is shown on the front of the frame. The smaller cylinder, the reactor 350, is shown in the center of the front face of the panel, while the output tank 700 is shown behind the main frame. Preferably, the system is housed in an enclosure with gas and leak detection, and appropriate ventilation, louvres and / or fans.Alternate Embodiments

[0044] An embodiment of the invention may use passive or active diffusion methods within the reactor to cause turbulence within the reactor, as discussed above.

[0045] An embodiment of the invention may use the heat generated by the reaction for a variety of uses, including electrical generation, battery charging or other uses requiring a heat source.

[0046] An embodiment of the invention may use its own PLC and user interface, while another embodiment may share the PLC, user interface, or both, with the anhydrous ammonia production system disclosed in US20220388855A1, entitled MODULAR, TRANSPORTABLE CLEAN HYDROGEN-AMMONIA MAKER and hereby incorporated by reference, if both systems are deployed at the same site.

[0047] A system for producing aqueous ammonia from anhydrous ammonia as shown in FIG. 1 - FIG. 2D. The system wherein the concentration of the produced aqueous ammonia may be changed. The system of claim 1 further configured to be on a mobile platform.

[0048] While some embodiments or aspects of the present disclosure may be implemented in fully functioning mechanical, chemical, electrical and electrical-mechanical systems, other embodiments may be considered.

[0049] The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and / or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is required for proper operation of the method that is being described, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

[0050] The specific embodiments described above have been shown by way of example and understood is that these embodiments may be susceptible to various modifications and alternative forms. Further understood is that the claims are not intended to be limited to the forms disclosed, but to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure. While the foregoing written description of the system enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The system should therefore not be limited by the above-described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the system. Thus, the present disclosure is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0051] Information as herein shown and described in detail is fully capable of attaining the abovedescribed object of the present disclosure, the presently preferred embodiment of the present disclosure, and is, thus, representative of the subject matter which is broadly contemplated by the present disclosure. The scope of the present disclosure fully encompasses other embodiments which may become obvious to those skilled in the art, and is to be limited, accordingly, by nothing other than the appended claims, wherein any reference to an element being made in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." All structural and functional equivalents to the elements of the above-described preferred embodiment and additional embodiments as regarded bythose of ordinary skill in the art are hereby expressly incorporated by reference and are intended to be encompassed by the present claims.

[0052] Moreover, no requirement exists for a system or method to address each problem sought to be resolved by the present disclosure, for such to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. However, various changes and modifications in form, material, workpiece, and fabrication material detail may be made, without departing from the spirit and scope of the present disclosure, as set forth in the appended claims, as may be apparent to those of ordinary skill in the art, are also encompassed by the present disclosure.

Claims

ClaimsWhat is claimed is:

1. A system for producing aqueous ammonia from anhydrous ammonia.

2. The system of claim 1, wherein the concentration of the produced aqueous ammonia may be changed.

3. The system of claim 1 further configured to be on a mobile platform.

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