FIELD OF THE INVENTION

Embodiments of the present invention generally relate to the field of ammonium bicarbonate, and, more particularly, to methods for preparing ammonium bicarbonate.

BACKGROUND OF THE INVENTION

There exists a strong need in the art for innovations that provide novel and inventive concepts pertaining to methods for preparing ammonium bicarbonate, specifically focussed on aspects that are aimed to achieve a carbon neutral chemical industry, and eventually a net-zero-CO2 world. It is well known that current processes use fossil fuels.

Generally, there are various processes known in the prior art literature for preparation of ammonium bicarbonate, which are incorporated herein in their entirety by reference. Certain disclosures provide methods for preparing ammonium bicarbonate with flue gas and devices thereof, wherein the flue gas from industrial or municipal boilers burning coal, natural gas, petroleum or the discharged gas from incinerating biomaterial containing a large amount of pollutants such as CO2, SO2, NOX, and dusts, etc.

In such methods, to reduce the pollution, the flue gas needs to be absorbed and processed before discharging. Currently, the process and utilization of flue gas mainly focuses on desulfurization, denitration and dust removing, while there are relatively less researches on the absorption and utilization of CO2, which is the most predominant ingredient of flue gas. In certain disclosures, the preparation of sodium bicarbonate. One of the patents regarding this technology is Canadian Patent No. 2,032,627, issued Jan. 14, 1997 to Thompson et. al. This reference teaches a process for producing sodium bicarbonateln the methodology, it is clearly stated on page 13, beginning at line 8: " . . . the brine remaining after screening off the solid sodium bicarbonate contains a mixture of unreacted sodium sulfate, ammonium sulfate, ammonium bicarbonate and minor amounts of sodium bicarbonate. This brine is transferred by a pump 36 into a gas recovery boiler 31 where it is heated to a temperature of 95° to 100° C. Under these conditions, the ammonium bicarbonate breaks down and sodium bicarbonate dissolved in the brine reacts with ammonium sulfate to produce sodium sulfate, carbon dioxide and ammonia. Carbon dioxide and ammonia dissolved in the brine boil off, leaving in the solution a mixture composed mostly of sodium and ammonium sulfate. The carbon dioxide and ammonia so regenerated are cooled in a gas cooler 32 and returned to the reactor 21 by a blower 33 after being further cooled in a gas cooler 34. This regeneration step minimizes the amount of carbon dioxide and ammonia used in the process."

However, it is well known that CO2 is currently one kind of greenhouse gas with the largest production globally, and is an important factor for climate warming. The reduction of its discharge has received increasing attention of countries all around the world. How to remove CO2 effectively and economically from industrial exhaust gas, especially from flue gas, becomes an exigent problem. In some countries, the conventional method for producing of ammonium bicarbonate, especially long effective ammonium bicarbonate, may be performed by using coal or natural gas as the raw material, and absorbing the shift conversion gas generated by burning the fuel with ammonia water, wherein when the natural gas is used as the raw material, it should be aided with burning limekiln gas to supplement the shortage of CO2 in the process of ammonia synthesis with natural gas.

It is also well known that anaerobic digestion is a common unit operation employed in the treatment of wastewaters containing organics and nitrogenous compounds including industrial, municipal and agricultural wastewaters. The resulting solid/liquid slurry from an anaerobic digester has a high-solids portion and a low-solids portion.

For example, the digestate produced from dairy wastewater, contains a high- solids portion comprising largely cellulosic solids and a low-solids portion containing concentrations of dissolved carbon dioxide and dissolved ammonia nitrogen as well as salts and both suspended and dissolved organics. The dissolved ammonia nitrogen in the digestate presents significant environmental issues if left untreated, such as, when the digestate is land applied, discharged to a body of water, or sent to a holding pond or lagoon. Potential adverse air and water impacts include: ammonia (toxic to fish, irritating to human eyes and lungs) will be lost both to the air and water; ammonia will be biologically oxidized either in water or soil and chemically oxidized in the air, in either case forming gases that are irritants and can form ozone or greenhouse gases, etc.

As disclosed in prior art literatures, most often regulations for ammonia release are designed to prevent excess nutrient input to surface waters which may cause eutrophication.

Also, effective treatment technologies are needed for agricultural and industrial waste streams that may release ammonia to the environment. For example, anaerobic digester digestate is often high in ammonia and their sources are required to remove ammonia nitrogen to avoid excessive nitrogen discharges. As disclosed in the prior art references, one well-established technology for treatment of digestate is air stripping which uses hot air and/or steam to strip ammonia from the wastewater creating a liquid stream comprising substantially less dissolved ammonia and a heated gas containing the stripped ammonia. Formation of a solid precipitate containing ammonia, ammonium bicarbonate, and ammonium carbonate, during the air stripping process may foul the air stripping substrates causing operational and maintenance issues and thus is not desired. An increase of the pH of the wastewater shifts the equilibrium for ammonia away from dissolved ionized ammonium and more to ammonia gas. Accordingly, increased removal of the ammonia from digestate using air stripping is commonly achieved with chemical addition. Examples of chemicals used to increase pH include calcium, sodium or magnesium hydroxide. The stripped ammonia is absorbed into an acid solution. The use of acids is highly effective for ammonia recovery and could also be effective in producing a concentrated ammonium salt product using subsequent unit operations. On the other hand, treatment utilizing industrial chemicals to raise pH with a stripping process and for absorption of ammonia, such as, for example, for a treatment system for a dairy waste which produces a nutrient rich solid for use as a fertilizer, has the unavoidable consequence stemming from the use of such chemicals that any reusable end product cannot be certified as an “organic” product. Stripper exhaust gas containing ammonia is sometimes released to the atmosphere although regulations typically require that it is further processed to capture the nitrogen. For example, U.S. Pat. No. 7,811 ,455 (Burke) describes a process for use of biogas rather than air and reclaiming ammonia from stripper exhaust gases in the form of ammonium bicarbonate by blending the CO2 in the digester biogas with the stripper gas and then precipitating and recovering ammonium bicarbonate with the added benefit of lowering CO2 in the biogas. One of the main drawbacks with that process is that the use of chemicals to raise the pH in the stripper precludes certification of the ammonium bicarbonate solids and any solids created from the ammonium bicarbonate solids as “organic” fertilizer. Another drawback is the inefficiency associated with processing large volumes of gas, including precipitation of ammonium bicarbonate in the gas phase.

Other prior art disclosures provide various processes, systems, and methods for treating wastewater wherein it states that high-Ammonia and ammonium containing wastewaters are produced in many industrial and municipal processes. Agriculture is one of the largest sources of these wastewaters, in particular in the form of products from the anaerobic digestion of organic waste. Examples of sources of this waste are animal manure, meat processing, dairy processing, and silage. Ammonia (NH3) that is not captured in a stable chemical form is a potential source of air and water pollution.

Such prior art literature provides a way to remove a substantial portion of the ammonia nitrogen within a liquid wastewater and capture the nitrogen in the form of crystallized ammonium bicarbonate using a series of unit operations operated under specified temperatures and without the use of chemicals to raise pH. The resulting ammonium bicarbonate solid is high in nitrogen content and could be used in combination with other materials to create a nitrogen rich organic fertilizer product. Specific embodiments of said prior art literature discloses at least three components: 1 ) removal of the ammonia from the waste (including without limitation sludges, semi-solids, and solids and liquids) without the use of chemicals at a temperature of at least 80 degrees Celsius thereby converting the ammonia to gaseous form; 2) mixing of the gaseous ammonia with carbon dioxide and water vapor at a temperature of between about 35 and 50 degrees Celsius causing the formation of dissolved ammonium bicarbonate in a liquid condensate and concentrating the dissolved ammonium bicarbonate using reverse osmosis also operating at a temperature of between about 35 and 50 degrees Celsius; and, 3) crystallizing the concentrated dissolved ammonium bicarbonate at a temperature below 35 degrees Celsius such that the reverse osmosis concentrate becomes saturated with dissolved ammonium bicarbonate which depends upon the concentrations of ammonium bicarbonate to form solid ammonium bicarbonate.

In operation, said prior art literatures are not limited to any one specific method or process to remove ammonia nitrogen from the waste but rather include numerous alternatives provided the operating temperatures for the components are followed. Stripping animal manure digestate at a temperature of at least 60 degrees Celsius and preferably at a temperature of at least 80 degrees Celsius, for example, is one way to remove ammonia nitrogen from animal waste creating an exhaust gas containing ammonia gas. Examples of other ways to remove ammonia nitrogen from wastewaters and create an ammonia- containing gas include dryers, and filtration devices with membrane modules and heat sources. However, all of these methods needs the consumption of a lot of energy or fuel resources, and meanwhile it may further increase the discharge of greenhouse gas CO2, deviating from the spirit of environmental protection.

Those of ordinary skills in the art will appreciate that various technical problems are associated with prior art, and accordingly, there remains a need in the art for innovative, novel, efficient solutions for providing a method for preparing ammonium bicarbonate.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the present invention, a method for preparing ammonium bicarbonate in a plant includes, reacting ammonia, Carbon Dioxide and DM water to form Ammonium Carbonate in a carbonation tower; reacting said ammonium carbonate with carbon dioxide in presence of DM water in Bicarbonation towers to form aqueous slurry containing Ammonium Bicarbonate crystals and mother liquor; centrifuging said aqueous slurry separates ammonium bicarbonate crystals from mother liquor; drying said crystals in a rotary drier to obtain the finished product; and, packaging, said finished product.

The embodiments of the present disclosure have several features, no single one of which is solely responsible for their desirable attributes. Without limiting the scope of the present embodiments as expressed by the claims that follow, their more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description”, one will understand how the features of the present embodiments provide advantages, which include providing a method of preparing ammonium bicarbonate.

DESCRIPTION OF THE INVENTION

Various embodiments of the present invention are disclosed herein below, which relate to a method of preparing ammonium bicarbonate. There are various embodiments of the present invention that are disclosed herein below that relate to the method of preparing Ammonium Bicarbonate from carbon dioxide (CO2) and ammonia (NH3). As it is known that CO2 is one of the greenhouse gases with the largest production globally, and is an important factor for climate warming. On the other hand, CO2 is also an important raw material in food and chemical fertilizer industries. Particularly, embodiments of the present invention are aimed at captive utilization of CO2, converting the greenhouse gas into a useful product i.e., Ammonium Bicarbonate, to protect the environment from harmful effects of CO2 when released into the atmosphere.

Those of ordinary skills in the art will appreciate that various embodiments of the present invention can be configured to enable the system of carbon credits, that is imposed on a given product or transaction in order to cause the transacting party or parties to internalize associated carbon emission costs (sometimes referred to as a “carbon footprint”). One well known adverse effect is the role that carbon dioxide emissions have on the Earth's ozone layer, and the resulting contribution to global warming.

With a view to combat the negative consequences resulting from energy utilization, various incentives have been developed to limit the amount of energy that any particular entity can consume. One such type of incentive is known as a “carbon credit”. In essence, an entity such as a manufacturing plant is issued a number of carbon credits that are based upon an amount of energy consumption by that entity, or resulting emissions from such consumption, that is considered to be acceptable. If the entity needs to consume more energy than the amount corresponding to its allotted carbon credits without incurring a penalty, it must acquire additional credits. Conversely, if the entity does not need to use all of its allotted credits, it can transfer them to another entity who is in need of additional credits. To date, the deployment of environmental incentives, such as carbon credits, has been limited in scope, and hence embodiments of the present invention may provide an option to deploy the carbon credit incentives.

In accordance with an embodiment of the present invention, the ammonia is obtained from the ammonia storage tank and carbon dioxide from the CO2 storage tank, installed in proximity to the main industrial plant, the present invention includes two paths, first the creation of ammonium carbonate and then the final product i.e, Ammonium Bicarbonate, the first using condensation to convert gaseous ammonia, CO2 and water vapor to a liquid solution containing ammonium carbonate and followed by filtration and the second to form concentrated dissolved ammonium bicarbonate. In use, the method is characterised in that wherein carbon dioxide is sourced from steam reforming of hydrocarbon.

In accordance with the embodiment of present invention, the process, method, and a system for the production of a nitrogen rich fertilizer from an ammonia (NH3) and carbon dioxide (CO2) using a process, method and/or system that comprises the preparation of dissolved ammonium bicarbonate using separation, followed by crystallization of concentrated ammonium bicarbonate, all at controlled operating temperatures.

In accordance with the embodiment of the present invention, the method of preparing Ammonium Bicarbonate in an Industrial plant is a two-step process that includes the first step of reacting ammonia (NH3), carbon Dioxide (CO2) and DM water to form Ammonium Carbonate in a carbonation tower; then reacting the ammonium carbonate with carbon dioxide in presence of DM water in a bcarbonation tower to form aqueous slurry containing Ammonium Bicarbonate crystals and mother liquor; the aqueous slurry is centrifuged that separates Ammonium Bicarbonate crystals from mother liquor; crystals are then dried in a rotary drier to obtain the finished product which is further packaged. In use, the Ammonium Bicarbonate produced in the process is used as chemical/nitrogen fertilizer. In operation, carbon dioxide is sourced from steam reforming of hydrocarbon, and wherein steam is provided to said drying section by using a hot air transmitter and a steam pressure transmitter with a control valve.

In accordance with an embodiment of the present invention, the first step of preparing Ammonium Bicarbonate by reacting ammonia (NH3), Carbon Dioxide (CO2) and DM water to form Ammonium Carbonate in a carbonation tower, is a continuous process and runs round the clock.

In accordance with an embodiment of the present invention, the industrial plant used in preparation of Ammonium Bicarbonate is a grassroot green field plant that comprises storage of raw material and end product facilities having carbonation tower, bicarbonation tower, centrifuge, mother liquor tank, venturi scrubbers, drying section, product bunker and bagging section. Moreover, the offshore utilities like steam, DM Water, Cooling Water, Instrument air and DG set for backup power for the plant are installed within the complex to cater to process demand. In operation, plant capacity is fixed as per the minimum processing capability of the system and then scaled up to make use of all surplus CO2.

In accordance with the embodiment of present invention, the ammonium bicarbonate synthesizing industrial plant comprises: a) a carbonation tower, which is a counter flow reacting section for concentrated ammonia, water and carbon dioxide, wherein the carbonation tower receives ammonia from the ammonia storage tank, and generates ammonium carbonate. b) a bicarbonate tower, which is a counter flow reacting apparatus for ammonium bicarbonate, water and carbon dioxide, the resultant being the aqueous slurry containing Ammonium Bicarbonate crystals and mother liquor. c) a separating system, comprising a thickener and a centrifuge, wherein the aqueous slurry containing ammonium bicarbonate crystals along with mother liquor is discharged into the centrifuge via slurry pumps, disposed in the proximity of the separating system. The discharge from the slurry pumps is led out with reduced pressure, fed first into the thickener, and then separated by the centrifuge to generate the final product of ammonium bicarbonate crystals. The centrifuge separates the mother liquor from the ammonium bicarbonate crystals. The mother liquor separated in the process is discharged into a mother liquor storage tank and passes through vent scrubbers. On the other hand, the Ammonium Bicarbonate crystals further discharged in a drying section at the bottom of the separating system led out with reduced pressure into the drying section. d) a drying section, the Ammonium Bicarbonate crystals obtained by separating the mother liquor in the separation system are dried in a rotary dryer in the drying section wherein the drying hot air, dries the crystals and produces the final product, i.e, Ammonium Bicarbonate. e) a dust removing apparatus, disposed in the drying section wherein the dust of salt escaping from the rotary dryer is separated and recovered in a cyclone separator wherein the residual dust along with air from cyclone separator is passed through a wet venturi scrubber for complete recovery of salt from outgoing air to atmosphere. f) a product bunker, the final product obtained is stored in the product bunker. The final product is then passed to the bagging section for packaging. g) a bagging section, wherein the final product obtained is then packaged in 25 kg of packaging.

In accordance with an embodiment of the present invention, the ammonia is obtained from an ammonia storage tank and carbon dioxide from a CO2 storage tank for the preparation of Ammonium Bicarbonate.

In accordance with an embodiment of the present invention, the second step of reacting Ammonium Carbonate with carbon Dioxide in the presence of DM water takes place in a Bicarbonation towers of the industrial plant, to form an aqueous slurry containing Ammonium Bicarbonate crystals and mother liquor. In use, this solution is kept in an aqueous state with excess water. In accordance with an embodiment of the present invention, in the second step, the conversion efficiency to Ammonium Bicarbonate crystals is about 25-40 % under strict temperature control.

In accordance with an embodiment of the present invention, the aqueous slurry is centrifuged, separating ammonium bicarbonate crystals from mother liquor. Subsequently, Ammonium Bicarbonate crystals are then dried in a rotary dryer to obtain the finished product which is further packaged in 25 kg packs in the bagging section of the industrial plant.

In accordance with an embodiment of the present invention, dust of salt escaping from the rotary dryer in the drying section of the industrial plant, is separated and recovered in a cyclone separator wherein the residual dust along with air from cyclone separator is passed through a wet venturi scrubber for complete recovery of salt from outgoing air to atmosphere.

In accordance with an embodiment of the present invention, the industrial plant used for the preparation of Ammonium bicarbonate is designed to produce 25 MT/Day to 60 MT/Day.

In accordance with an embodiment of the present invention, for all purposes during the process, only DM Water is used since the product is food grade and can't be contaminated with foreign ingredients. In use, the method is prepared in grass root green field plant further comprising the main plant with carbonation tower, bicarbonation tower, a plurality of slurry pumps, drying section, product bunker, end product in bagging section, and, storage of raw material. Also, the finished product is packed in 25 kgs packs in said bagging and storing section of said grassroot green field plant that further includes a product bunker before said bagging and storing section having a product temperature transmitter. As disclosed herein, this method uses only DM water that takes part in the process reaction through a plurality of vent scrubbers. Furthermore, the present method is a continuous process and runs round the clock. As further disclosed, the ammonia is obtained from an ammonia storage tank and carbon dioxide from a CO2 storage tank. For this invention, carbon dioxide is obtained from various sources that otherwise cause environmental damage.

Those of ordinary skills in the art will appreciate that the CO2 is stored in CO2 storage tanks and various embodiments of the instant invention are aimed at providing environment friendly aspects, such as reducing the CO2 adverse effects that are caused to the environment.

The embodiments of the present invention are aimed at disclosing new conversion technologies are allowing the energy-hungry chemical reactions to proceed more efficiently. Renewable sources such as solar and wind can increasingly supply that energy at a competitive cost without the carbon penalty. And solutions to the capture problem may be forthcoming if governments follow the recommendations of the Intergovernmental Panel on Climate Change (IPCC) and mandate carbon capture and storage — grabbing the CO2 coming out of power plants and other industries, and locking it away underground. But rather than simply burying it, companies could defray the cost of capture by putting the gas to productive use (see Nature 526, 306-307; 2015).

Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. The terms "comprising," "including," 'having," and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term "or" is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term "or" means one, some, or all of the elements in the list.

While there has been shown and described the preferred embodiment of the instant invention it is to be appreciated that the invention may be embodied otherwise than is herein specifically shown and described and that, within said embodiment, certain changes may be made in the form and arrangement of the parts without departing from the underlying ideas or principles of this invention as set forth in the Claims appended herewith. Therefore, the appended claims are to be construed to cover all equivalents falling within the true scope and spirit of the invention.