WO2014099561A1

WO2014099561A1 - System and method for recycling in an andrussow process

Info

Publication number: WO2014099561A1
Application number: PCT/US2013/074515
Authority: WO
Inventors: Stewart Forsyth; Martin J. Renner; Aiguo Liu; Brent J. STAHLMAN
Original assignee: Invista Technologies S.A R.L.
Priority date: 2012-12-18
Filing date: 2013-12-12
Publication date: 2014-06-26
Also published as: TW201441157A; CN110372008A; CN103864109A; HK1198995A1

Abstract

A method and a system for utilizing waste produced during production of hydrogen cyanide are described herein.

Description

SYSTEM AND METHOD FOR RECYCLING IN AN ANDRUSSOW PROCESS

CROSS-REFERENCE TO RELATED APPLICATION

[001] This application claims the benefit of priority to U.S. Provisional Patent

Application Serial No. 61/738,895 entitled "SYSTEM AND METHOD FOR RECYCLING IN AN ANDRUSSOW PROCESS," filed December 18, 2012, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

[002] The present disclosure is directed to a recycling scheme for the Andrussow process for the production of hydrogen cyanide (HCN) from methane, ammonia, and oxygen.

BACKGROUND

[003] The Andrussow process is used for gas phase production of hydrogen cyanide

(HCN) from methane, ammonia, and oxygen over a platinum-containing catalyst. Ammonia, methane, and oxygen are fed into a reactor and heated to a reaction temperature in the presence of a catalyst that comprises platinum. The methane can be supplied from natural gas, which can be further purified. Hydrocarbons having two carbons, three carbons, or more can be present in natural gas. While air can be used as a source of oxygen, the reaction can also be carried out with oxygen-enriched air or undiluted oxygen (e.g., an oxygen Andrussow process). The reactor off-gas containing HCN can be sent through an ammonia absorption process to remove un- reacted ammonia. This can be accomplished by contacting with an ammonium phosphate solution, phosphoric acid or sulfuric acid to remove the ammonia. From the ammonia absorber the product off-gas can be sent through an HCN absorber where cold water can be added to entrain the HCN. The HCN- water mixture can be sent to a cyanide stripper where HCN can be separated from the water and other materials.

[004] Various aspects of the Andrussow process are described in the following articles:

N.V. Trusov, Effect of Sulfur Compounds and Higher Homologues of Methane on Hydrogen Cyanide Production by the Andrussow Method, Rus. J. of Applied Chemistry, Vol. 74, No. 10, pp. 1693-97 (2001); Clean Development Mechanism (CDM) Executive Board, United Nations Framework Convention on Climate Change (UNFCCC), Clean Development Mechanism Project Design Document Form (CDMPDD), Ver. 3, (Jul. 28, 2006), available online at http://cdm.unfccc.int/Reference/PDDs_Forms/PDDs/PDD brm04_v03_2.pdf Gary R. Maxwell et al., Assuring process safety in the transfer of hydrogen cyanide manufacturing technology, J. of Hazardous Materials, Vol. 142, pp. 677-84 (2007); Eric. L. Crump, U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Economic Impact Analysis For the Proposed Cyanide Manufacturing NESHAP (May 2000), available online at

http://nepis.epa.gov/Exe/ZyPDF. cgi?Dockey=P 100AHG1.PDF, the disclosures of which are incorporated by reference as if reproduced herein.

SUMMARY

[005] The problem of thermal waste and material waste in an Andrussow process is solved or improved by recovering energy from heat generated from the reaction producing HCN and recovering energy from burning the gaseous waste stream. The present disclosure is directed to methods for utilizing waste produced during an Andrussow process (e.g., during an oxygen- enriched or oxygen Andrussow process). The present disclosure also provides systems that can operate during production of hydrogen cyanide and reduce the amount of energy or material that is wasted during an Andrussow process.

[006] Some problems of using oxygen-enriched or substantially pure oxygen feedstreams are readily understood. For example, oxygen-enriched and substantially pure oxygen feedstreams are more expensive than air. Oxygen-enriched and substantially pure oxygen feedstreams can include concentrated oxygen sources and produce waste streams that contain high levels of hydrogen. Thus, added care is used to avoid problems relating to the use of pure oxygen as the gaseous oxygen feed stream. For example, safety concerns, equipment design, equipment maintenance, and operating conditions that are not generally used or needed in an air Andrussow process can be needed for dealing with safety issues raised by combining hydrogen recovery with an oxygen-enriched or oxygen Andrussow process.

[007] Very few oxygen-enriched or oxygen Andrussow manufacturing facilities exist or have been built. In addition to the more readily apparent concerns associated with oxygen- enriched or oxygen Andrussow manufactuiing facilities such as those described above, there are a multitude of additional problems that are not readily or widely understood.

[008] For example, an oxygen-enriched or oxygen Andrussow process is more sensitive to variations in concentration of reactants than in an Andrussow process that employs air. Variations in concentration or flow rate of reactants in an oxygen-enriched or oxygen Andrussow process can cause larger changes in the efficiency of the process than are observed in an air Andrussow process. An oxygen-enriched or oxygen Andrussow process is more sensitive to changes in a heating value (British Thermal Units (BTU)) of the feed gas; small variations in the composition of the feedstream can cause greater temperature fluctuations in the reactor than would be observed for similar feedstream compositions in an air Andrussow process. Local variations in the concentration of reactants traveling past the catalyst can cause temperature variations in the catalyst bed, such as hot spots, which can reduce the life of the catalyst as compared to an air Andrussow process. The presence of about 78 vol% nitrogen in air serves to dilute the gas mixture in an air Andrussow process and can reduce the production of by-products and the need for heightened control of the reaction. The gaseous waste stream of an air

Andrussow process (e.g., the stream after the HCN recovery), has a low heating value such that the stream would need to be supplied with a fuel gas (e.g., natural gas) to complete combustion. Therefore, the air Andrussow process gaseous waste stream is not meaningful as a fuel gas.

[009] Heat transfer from the effluent of an oxygen-enriched or oxygen Andrussow process poses more problems than observed for an air Andrussow process. The effluent from an oxygen-enriched or oxygen Andrussow process is more concentrated than for an air Andrussow process. While cooling such a concentrated effluent is best done quickly to stop reactants from forming by-products, the effluent should not be cooled to the point of HCN condensation because the HCN has a greater propensity for polymerization when condensed.

[010] An oxygen-enriched or oxygen Andrussow process tends to proceed in a more concentrated fashion than an air Andrussow process. As such, an oxygen-enriched or oxygen Andrussow process tends to generate a higher concentration of all products, including byproducts. Hence, the reactor and associated equipment for an oxygen-enriched or oxygen Andrussow process is more susceptible to the build-up of impurities in the system that can more easily be flushed out of the equipment employed in an air Andrussow process. The greater rate of by-product build-up can lead to increased rates of corrosion as well as more frequent shut down and maintenance of various parts of the process. Equipment that can be significantly affected by by-product build-up, corrosion and related problems include, for example, heat recovery system(s), the reactor(s), the ammonia recovery system(s), and the HCN recovery system(s). [Oil] Although the equipment needed for production of an equivalent amount of HCN can be more compact (i.e., smaller) for an oxygen-enriched or oxygen Andrussow process than for an air Andrussow process, many manufacturers would choose to operate an air Andrussow process to avoid the problems associated with an oxygen-enriched or oxygen Andrussow process. The problems associated with combining an oxygen-enriched or oxygen Andrussow process with utilizing waste produced during the oxygen-enriched or oxygen Andrussow process are not well understood and the difficulties are of sufficient magnitude that most manufacturers would not attempt such a combination.

[012] However, the benefits can be surprisingly large. Various examples of the present disclosure can generate energy from waste such as thermal waste and material waste, produced during the production of HCN from an oxygen-enriched or oxygen Andrussow process. For example, co-generation units can be utilized after the reactor and after HCN recovery to generate electricity and heat. The various examples can reduce the cost of producing HCN during an oxygen-enriched or oxygen Andrussow process by recycling the generated heat and electricity back into the process thereby minimizing the amount of externally supplied energy and minimize the amount of material waste. The benefits described with respect to the oxygen-enriched or oxygen Andrussow process were not plausible in an air Andrussow process.

[013] The conversion of ammonia and methane to HCN is an endothermic reaction, but in an Andrussow process the reaction is converted to an exothermic catalytic reaction by using ammonia, methane, oxygen, and a suitable catalyst, such as a Pt-containing catalyst. Producing HCN via the Andrussow process can occur at reaction temperatures greater than 800 °C, for example, about 800 to 2,500 °C or 1,000 to about 1,500 °C. Supplying energy to heat the reactant feed streams to the reaction temperature can be costly. Additionally, if the heat generated by the reaction is not recaptured and converted to energy, the generated heat can be considered thermal waste. Additionally, recovering the heat generated can decrease the temperature of the product stream and prevent components of the product stream from forming by-products. In various examples, the present disclosure can recover a portion of the heat and generate both electricity and heat, which can be recycled back into the process. For example, a co-generation unit can be utilized to generate steam and electricity. Recycling the electricity and heat back into the process can reduce the amount of externally supplied energy, minimize the amount of heat waste, and improve the overall efficiency of the process. [014] In various examples, material waste (e.g., chemical waste) can be produced during the production of HCN. For example, in an oxygen Andrussow process about 40,000 standard cubic feet (set) of waste gas can be produced for 1,000 pounds (lbs) of HCN and 235 BTU/scf can be lost. As discussed herein, as the oxygen percentage in the feed gas increases (e.g., in an oxygen Andrussow process), the hydrogen and other combustible components (such as carbon monoxide increases) such that the gaseous waste stream can be used as a fuel. In various examples, the present disclosure can convert the chemical waste into energy. For example, a co-generation unit can be utilized in a gaseous waste stream from an oxygen or oxygen-enriched Andrussow process and generate heat and electricity. By recovering energy from material waste, the various examples of present disclosure can reduce the amount of material wasted during the production of HCN and can produce HCN more efficiently than other processes (e.g., an air Andrussow process). For example, the various examples can reduce the overall cost of producing hydrogen cyanide by reducing the amount of externally supplied energy and minimize the amount of material waste.

[015] In various examples, the present disclosure provides a method of utilizing waste produced during production of hydrogen cyanide. The method can include burning a gaseous waste stream for primary energy generation, wherein the gaseous waste stream is from a reactor configured to produce hydrogen cyanide, and the gaseous waste stream is substantially free of hydrogen cyanide. The method can include contacting a heat recovery unit with heat for secondary energy generation, where the heat is generated by a reactor during production of the hydrogen cyanide. In various examples, the method can include both burning the gaseous waste stream for primary energy generation and contacting a heat recovery unit with heat for secondary energy generation. The primary or secondary energy generation can include heat transfer, steam generation, electricity generation or a combination thereof.

[016] In various examples, the present disclosure provides a system for producing hydrogen cyanide via the Andrussow process. The system includes a reactor configured for producing hydrogen cyanide from a reaction mixture comprising methane, ammonia and oxygen in the presence of a catalyst comprising platinum, wherein the reactor is also configured to supply the reaction mixture with sufficient oxygen to generate a gaseous waste stream that has at least 59 volume percent hydrogen after removal of ammonia and recovery of hydrogen cyanide. The system can include a first cogeneration unit configured to burn the gaseous waste stream as a fuel for primary energy generation, wherein the gaseous waste stream is substantially free of hydrogen cyanide. The system can include a second cogeneration unit configured to absorb heat from the reactor for secondary energy generation. In various examples, the system can include both the first cogeneration unit and the second cogeneration unit.

[017] In various examples, the present disclosure provides a method. The method can include adjusting a reaction mixture comprising methane, ammonia and oxygen to provide the reaction mixture with sufficient oxygen to generate a gaseous waste stream that has at least 59 volume percent hydrogen in the gaseous waste stream after removal of ammonia and recovery of hydrogen cyanide. The method can further include burning the gaseous waste stream for energy generation.

[018] These and other examples and features of the present methods and devices will be set forth in part in the following Detailed Description. This Summary is intended to provide an overview of the present subject matter, and is not intended to provide an exclusive or exhaustive explanation. The Detailed Description below is included to provide further information about the present systems and methods.

BRIEF DESCRIPTION OF THE FIGURES

[019] In the drawings, which are not necessarily drawn to scale, like numerals describe substantially similar components throughout the several views. The drawings illustrate generally, by way of example, but not by way of limitation, various examples discussed in the present document.

[020] FIG. 1 is a flow diagram of a process for the production of hydrogen cyanide

(HCN) via the Andrussow process, in accordance with various examples.

[021] FIG. 2 is a more detailed flow diagram of a portion from process 11 of FIG. 1, in accordance with various examples.

[022] FIG. 3 is a more detailed flow diagram of a portion of the process of FIG. 1 for the production of HCN, in accordance with various examples.

DETAILED DESCRIPTION

[0001] Reference will now be made in detail to certain claims of the disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that they are not intended to limit the disclosed subject matter to those claims. On the contrary, the disclosed subject matter is intended to cover all alternatives, modifications, and equivalents, which can be included within the scope of the presently disclosed subject matter as defined by the claims. The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific examples in which the invention may be practiced.

[0002] References in the specification to "one example," "an example," etc., indicate that the example described can include a particular feature, structure, or characteristic, but every example may not necessarily include the particular feature, structure, or characteristic.

Moreover, such phrases are not necessarily referring to the same example. Further, when a particular feature, structure, or characteristic is described in connection with an example, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other examples whether or not explicitly described.

[023] The term "about" can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range. When a range or a list of sequential values is given, unless otherwise specified any value within the range or any value between the given sequential values is also disclosed.

[024] The term "air" as used herein refers to a mixture of gases with a composition approximately identical to the native composition of gases taken from the atmosphere, generally at ground level. In some examples, air is taken from the ambient surroundings. Air has a composition that includes approximately 78% nitrogen, 21% oxygen, 1% argon, and 0.04% carbon dioxide, as well as small amounts of other gases.

[025] As used herein, an air Andrussow process uses air as the oxygen-containing feedstream, having approximately 20.95 mol% oxygen.

[026] An oxygen-enriched Andrussow process uses an oxygen-containing feed stream having about 21 mol% oxygen to about 26%, 27%, 28%, 29%, or to about 30 mol% oxygen, such as about 22 mol% oxygen, 23%, 24%, or about 25 mol% oxygen.

[027] As used herein, an oxygen Andrussow process uses an oxygen-containing feed stream having about 26 mol% oxygen, 27%, 28%, 29%), or about 30 mol% oxygen to about 100 mol% oxygen. An oxygen Andrussow process can also use an oxygen-containing feed stream having about 35 mol% oxygen, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or about 100 mol% oxygen.

[028] The term "substantially free" as used herein refers to less than about 1 wt%, less than about 0.5 wt%, and less than about .10 wt%.

[029] This disclosure describes methods and systems for utilizing waste produced during production of hydrogen cyanide (HCN) from an Andrussow process. The methods and systems of the present disclosure can safely solve the problems of wasteful loss of heat and material from an oxygen-enriched or oxygen Andrussow process by use of the methods and systems described herein. The methods and systems can involve burning a gaseous waste stream for the generation of energy. The methods and systems of the present disclosure can also involve generating energy from the heat given off from the reaction for producing HCN. In various examples, the energy generated from waste can be used and recycled back into the process for producing HCN. Thus, the methods and systems of the present disclosure can reduce the amount of energy or material in an Andrussow process that is waste.

[030] During an Andrussow process, reactant gas feedstreams including a gaseous ammonia feedstream, a gaseous methane feedstream and a gaseous oxygen feedstream react to form a product stream that contains hydrogen cyanide and water. As discussed herein, the synthesis of hydrogen cyanide by the Andrussow method (see, for example, Ullmann's

Encyclopedia of Industrial Chemistry, Volume 8, VCH Verlagsgesellschaft, Weinheim, 1987, pp. 161-162) can be carried out in the vapor phase over a catalyst that comprises platinum or platinum alloys, or other metals. Catalysts suitable for carrying out the Andrussow process were discovered and described in the original Andrussow patent, published as U.S. Pat. No. 1,934,838, and elsewhere. In Andrussow' s original work, he disclosed that catalysts can be chosen from oxidation catalysts that are infusible (solid) at the working temperature of around 1000°C; he included platinum, iridium, rhodium, palladium, osmium, gold or silver as catalytically active metals either in pure form or as alloys. He also noted that certain base metals, such as rare earth metals, thorium, uranium, and others, could also be used, such as in the form of infusible oxides or phosphates, and that catalysts could either be formed into nets (screens), or deposited on thermally-resistant solid supports such as silica or alumina.

[031] In subsequent development work, platinum-containing catalysts have been selected due to their efficacy and to the heat resistance of the metal even in gauze or net form. For example, a platinum-rhodium alloy can be used as the catalyst, which can be in the form of a metal gauze or screen such as a woven or knitted gauze sheet, or can be disposed on a support structure. In an example, the woven or knitted gauze sheet can form a mesh-like structure having a size from 20-80 mesh, e.g., having openings with a size from about 0.18 mm to about 0.85 mm. A catalyst can comprise from about 85 wt% to about 90 wt% platinum (Pt) and from about 10 wt% to about 15 wt% rhodium (Rh). A platinum-rhodium catalyst can also comprise small amounts of metal impurities, such as iron (Fe), palladium (Pd), iridium (Ir), ruthenium (Ru), and other metals. The impurity metals can be present in trace amounts, such as about 10 ppm or less.

[032] A broad spectrum of possible embodiments of the Andrussow method is described in German Patent 549,055. In one example, a catalyst comprising a plurality of fme- mesh gauzes of Pt with 10% rhodium disposed in series is used at temperatures of about 800 to 2,500° C, 1,000 to 1,500° C, or about 980 to 1050° C. For example, the catalyst can be a commercially-available catalyst, such as a Pt-Rh catalyst gauze available from Johnson Matthey Pic, London, UK, or a Pt-Rh catalyst gauze available from Heraeus Precious Metals GmbH & Co., Hanau, Germany.

[033] Andrussow processes can be performed using a variety of sources for the gaseous oxygen feedstream. For example, the gaseous oxygen feedstream can be pure oxygen, mixtures of oxygen with inert gases, as well as mixtures of air and oxygen. In general, a greater percentage of oxygen in the gaseous oxygen feedstream will give rise to a greater percentage of hydrogen in the gaseous waste stream. For example, an Andrussow process that employs a gaseous oxygen feedstream that is substantially pure oxygen can yield a gaseous waste stream with as much as 70-80 vol % hydrogen. However, an Andrussow process that employs air as its gaseous oxygen feedstream has substantially less hydrogen in its gaseous waste stream, for example, as little as 15-18 vol%. As discussed herein, the gaseous waste stream of an air Andrussow process that has not been supplemented with fuel gas is not generally useful as a fuel gas. Hence, burning the gaseous waste stream to generate energy in an oxygen-enriched or substantially pure oxygen Andrusso process having more than 55 vol % of oxygen in the oxygen feed stream may be more economically attractive than burning the gaseous waste stream in an air Andrussow process. For example, the gaseous waste stream from an air Andrussow process will need to be supplemented with a fuel gas in order to include enough fuel to be useful for energy generation (e.g., via a cogeneration unit). [034] As used herein, an air Andrussow process uses air as the oxygen-containing feedstream, having approximately 20.95 vol% oxygen. An oxygen-enriched Andrussow process uses an oxygen-containing feed stream having about 21 vol% oxygen to about 26%, 27%, 28%, 29%, or to about 30 vol% oxygen, such as about 22 vol% oxygen, 23%, 24%, or about 25 vol% oxygen.

[035] An oxygen Andrussow process uses an oxygen-containing feed stream having about 26 vol% oxygen, 27%, 28%, 29%, or about 30 vol% oxygen to about 100 vol% oxygen. An oxygen Andrussow process can also use an oxygen-containing feed stream having about 35 vol% oxygen, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or about 100 vol% oxygen.

[036] In various examples, the oxygen-containing feedstream in an oxygen-enriched

Andrussow process, or in an oxygen Andrussow process with an oxygen-containing feedstream having less than 100 vol% oxygen, can be generated by mixing air with oxygen, by mixing oxygen with any suitable gas or combination of gases, or by removing one or more gases from an oxygen-containing gas composition such as air.

[037] FIG. 1 is a flow diagram of a process 11 for the production of hydrogen cyanide

(HCN) via the Andrussow process, in accordance with various examples. In the example process 11, a HCN synthesis system 8 includes one or more unit operations configured to produce HCN. In various examples, the HCN synthesis system 8 is supplied with an ammonia (N¾) stream 2, a methane (CH₄) stream 4, and an oxygen stream 6 (which includes oxygen gas (0₂)). The three feed streams 2, 4, 6, are mixed and reacted in a plurality of reactors to be converted to hydrogen cyanide and water in the presence of a suitable catalyst according to Equation 1 :

2 N¾ + 2 CH₄ + 3 0₂→2 HCN + 6 H₂0 [1]

[038] The resulting product stream 10 from the HCN synthesis system 8 can be fed into a thermal waste utilization system 12 (discussed in further detail in FIG. 2). The reaction of Equation 1 for producing HCN using the Andrussow process is exothermic and generates heat. If the heat is not recaptured, the generated heat can be considered thermal waste. Additionally, by removing the heat from the product stream 10, the process 11 can minimize the amount of byproduct formation. The thermal waste utilization system 12 can include one or more unit operations configured to utilize the thermal waste and generate energy. In various examples, the energy generated by the thermal waste utilization system 12 can include heat transfer, steam generation, electricity generation or a combination thereof. In one example, the thermal waste utilization system 12 generates steam. The generated steam can be used to recuperatively preheat one or more of the reactant feed streams, for example, streams 2, 4, and 6, which can reduce the amount of externally supplied heat that elevates the temperature of the feed streams 2, 4, and 6 to the reaction temperature. In one example, the thermal waste utilization system 12 generates electricity. The generated electricity can be used to supplement the electricity needs of the process 11 for producing HCN.

[039] After heat has been removed from product stream 10, a resulting reduced- temperature product stream 14 can be fed into an ammonia recovery system 16. The

composition of stream 14 and stream 10 are substantially the same, but stream 14 has a lower temperature than stream 10. The ammonia recovery system 16 can include one or more unit operations configured to recover unreacted NH₃. Ammonia can be recovered by NH₃ absorption via contacting with one or more of phosphoric acid (H₃P0₄), sulfuric acid (H₂S0₄), and an ammonium phosphate solution, that can absorb NH₃ from the product stream 10. In the example shown in FIG. 1, a phosphoric acid stream 18 is added to the ammonia recovery system 16 to absorb NH₃. In the case of an H₃P0₄ solution, ammonia can be removed from the resulting ammonium phosphate solution using one or more strippers to separate the NH₃ from the H₃P0₄. The N¾ can be recycled back to the NH₃ feed stream 2 via an NH₃ recycle stream 20. The H₃P0₄ and other waste can be purged as a wastewater stream 22, while an NH₃-stripped HCN stream 24 can be fed to an HCN recovery system 30.

[040] The HCN recovery system 30 can include one or more unit operations configured to separate and purify HCN from the NH₃-stripped HCN stream 24. As a result of the HCN recover system 30, a purified HCN product stream 32 is produced. The HCN recovery system 30 can also produce a gaseous waste stream 34 and a wastewater stream 28. Wastewater stream 28 from the HCN recovery system 30 can be fed into wastewater treatment system 26. Waste water treatment system 26 can further process wastewater streams 22, 28, for example, by further treatment, storage, or disposal. Prior to being fed to the waste water treatment system 26, either or both of wastewater streams 22 and 28 can be processed to recover additional ammonia, which can be recycled back to the ammonia recovery system 16.

[041] In various examples, process 11 can include a material waste utilization system 36 that generates energy from waste. The gaseous waste stream 34 can include a variety of gases including hydrogen, unreacted methane, carbon dioxide, carbon monoxide, water, nitrogen, a variety of organonitriles, and trace amounts of HCN. Flaring the gaseous waste stream 34 is wasteful and creates material waste.

1042 ] In various examples, the gaseous waste stream 34 can be fed to a material waste utilization system 36, an H₂ recovery system 38, a flare 42, or combinations thereof. In various examples, the gaseous waste stream 34 can be diverted, in whole or in part, from the material waste utilization system 38 and to the H₂ recovery system 38 and/or the flare 42. In various examples, the gaseous waste stream 34 can be divided between the material waste utilization system 36, the H₂ recovery system 38, and the flare 42.

1043] In various examples, the material waste utilization system 38 can be configured to burn the gaseous waste stream 34 and generate energy. The energy generated can include electricity generation, steam generation, heat transfer and combinations thereof. In an embodiment(s), where electricity is generated, the generated electricity can be used to supplement the external supply of electricity for the production of HCN. In various examples, the material waste utilization system 38 can capture a portion of the heat generated from burning the gaseous waste stream 34 and be recycled to preheat the feed stream reactants.

[044] The H₂ recovery system 38 can be configured to recover hydrogen from the gaseous waste stream 34. The recovered H₂ 40 can be stored or further processed. For example, the recovered ¾ 40 can be employed for hydrogenation. As discussed herein, a portion of the gaseous waste stream 34 can be sent to the flare 42. The flare 42 can be used to destroy any excess gases produced. However, the various examples minimize flaring and thereby minimize the material waste produced during the production of HCN, as discussed herein.

[045] FIG. 2 is a more detailed flow diagram of portion 46 from process 11 of FIG. 1, in accordance with various examples. As shown in FIG. 2, only one reactor 66 is illustrated for simplicity. However, a plurality of reactors 66 can be connected in series and used to produce HCN. The reactor 66 can include a catalyst bed. The catalyst bed can comprises a catalyst material that is capable of catalyzing Reaction 1, such as a catalyst comprising platinum (Pt). In an embodiment, the catalyst bed comprises a platinum and rhodium (Rh) catalyst, such as a catalyst comprising about 85 wt% to about 95 wt% Pt and about 5 wt% to about 15 wt% Rh, such as 85/15 Pt/Rh, 90/10, or 95/5 Pt/Rh. The catalyst of the catalyst bed can also comprise small amounts of metal impurities, such as iron (Fe), palladium (Pd), iridium (Ir), ruthenium (Ru), and other metals. The impurity metals can be present in trace amounts, such as about 10 parts per million (ppm) or less.

[046] The catalyst bed can be formed with the catalyst, such as the Pt-Rh catalyst described above, on a support structure, such as a woven or knitted gauze sheet, a corrugated catalyst structure, or a supported catalyst structure. In an example, the woven or knitted gauze sheet can form a mesh-like structure having a size from 20-80 mesh, e.g., having openings with a size from about 0.18 mm to about 0.85 mm. The amount of catalyst that is present in the catalyst bed can depend on the feed rate of the reaction mixture 64 being feed to the reactor 66. In an embodiment, the mass of catalyst in the catalyst bed is from about 0.4 grams (g) to about 0.6 g per feed rate, in pounds per hour, of the reaction mixture being fed to the reactor 66. The catalyst of the catalyst bed can be a commercially-available catalyst, such as a Pt-Rh catalyst gauze available from Johnson Matthey Pic, London, UK, or a Pt-Rh catalyst gauze available from Heraeus Precious Metals GmbH & Co., Hanau, GERMANY.

[047] The HCN synthesis system 8 (illustrated in FIG. 1) can include operations for preparing each feed stream, e.g., the N¾ stream 2, the CH₄ stream 4, and the oxygen stream 6, to be at desired conditions in order to effectuate reaction according to Equation 1 and to produce HCN. For example, the NH₃ feed stream 2, which can be fed as a liquid, can be vaporized by an ammonia vaporizer 56 that can vaporize the liquid N¾ stream 2 into an NH₃ vapor stream 58. The NH₃ vapor stream 58 can be further heated in an NH₃ super heater 54 to form a superheated NH₃ vapor 60.

[048] In various examples, the CH₄ stream 4 can be provided as a hydrocarbon feed comprising natural gas, biogas, substantially pure methane or mixtures thereof. In one embodiment, the CH₄ stream 4 is in the form of a natural gas feed. The composition of the natural gas feed can be a majority CH with small percentages of other hydrocarbons. In an embodiment, the natural gas feed 4 can be about 90 wt% to about 97 wt% CH₄, about 3 wt% to about 10 wt% ethane (C₂H₆), about 0 wt% to about 5 wt% propane (C₃H₈), about 0 wt% to about 1 wt% butane (C₄H₁₀, either in the form of isobutene, n-butane or a combination thereof), and trace amounts of higher hydrocarbons and other gases. The natural gas feed can also be purified to comprise a more pure source of methane. In an embodiment, a purified natural gas feed can comprise about 99.9% CH₄ and less than about 0.1 wt% other hydrocarbons (which are primarily ethane). The natural gas feed can be heated by a gas heater 52. [049] The oxygen stream 6 can be pressurized, such as with a compressor 50 (e.g., an air compressor). The oxygen stream 6 can be provided as an oxygen-rich or substantially pure oxygen feeds stream. For example, such an oxygen stream 6 can contain at least about 25 vol% oxygen, at least about 30 vol% oxygen, at least about 40 vol% oxygen, at least about 50 vol% oxygen, at least about 60 vol% oxygen, at least about 70vol % oxygen, at least about 80 vol% oxygen, at least about 90 vol% oxygen, at least about 95% oxygen, at least about 98% oxygen. Substantially pure oxygen can also be employed as the oxygen stream 6.

[050] The three feed streams 2, 4, 6, can be combined in preheater 62, where the preheater 62 can assist in heating the reaction mixture to the reaction temperature. In various examples, the preheater 62 can include a gas mixer that is configured to form a reaction mixture feed stream 64 comprising gaseous ammonia, methane, and oxygen gas. In various examples, preheater 62 may contact one or more of the three feed streams 2, 4, and 6, before forming the reaction mixture feed stream 64, with heat (e.g., steam 72) that is generated from a cogeneration unit 74 using thermal waste from the reactor 66. As illustrated in process 11, the feed streams 2, 4, 6 are combined prior to entering the reactor 66. In some examples, the mixing can occur within a mixing zone of the reactor 66 before entering a reactor zone of reactor 66. In some examples, a portion of the product stream 10 leaving the reactor 66 can be recovered in a storage tank 68 and sent back to the preheater 62 by a stream 69.

[051] As discussed herein, a portion of the heat possessed by the product stream 10 leaving the reactor 66 can be recovered and recycled. In various examples, the heat waste utilization system 12 can include the cogeneration unit 74 that includes a boiler 70 and a generator 78 (e.g., a heat-activated generator) configured to generate both electricity and heat. The product stream 10 can enter the boiler 70 and the heat energy contained in the product stream 10 can be used to create steam. For example, the generated heat of the product stream 10 can be contacted with the water to make steam.

10521 As discussed herein, the preheater 62 may receive a portion of the steam 72 generated from boiler 70 to heat the feed streams 2, 4, 6. As illustrated in FIG. 2, the three feed streams 2, 4, 6 are mixed and heated within the preheater 62. The preheater 62 can reduce the amount of externally supplied energy to heat the feed streams to the reaction temperature, as compared to a process that does not include the preheater 62. [053] The cogeneration unit 74 of the heat waste utilization system 12 can include a generator 78 (e.g., a heat-activated generator) configured to generate electricity from the heat generated by the boiler 70. A portion of the steam 76 can be fed to the generator 78 to generate electricity. The electricity can be used in the process 11 for producing HCN, which reducing the amount of externally supplied energy.

[054] In various examples, the product stream 10 from the reactor 66 can have a first temperature. After the product stream 10 has passed through the co-generation unit 74, the reduced temperature product stream 14 can have a second temperature, where the second temperature is less than the first temperature. In various examples, the first temperature can be about 1000 °C to about 1300 °C and the second temperature of the reduced temperature product stream 14 can be about 450 °C to about 240 °C . As discussed herein, the cogeneration unit 74 can quickly absorb the heat and reduce the heat of the product stream 10 to minimize byproducts.

[055] As illustrated in FIG.2, a single boiler 70 and generator 78 is used to generate steam and electricity. In some examples, another boiler (not shown) can be used to remove additional heat from the reduced temperature product stream 14 prior to entering the ammonia recovery system 16. For example, the reduced temperature product stream 14 can enter an additional boiler that could create additional steam that can be recirculated back into the process. In various examples, heat generation may be more advantageous than electricity. In that example, the boiler 70 can be utilized without the generator 78 to product steam.

[056] The heat waste utilization system 12 can be employed in an air Andrussow process, an enriched-oxygen Andrussow process, and an oxygen Andrussow process. However, it may be more advantageous to utilize the heat waste utilization system 12 in an enriched- oxygen or an oxygen Andrussow process due to the increased concentration of combustible components. Thus, the risk of igniting the product stream 12 or producing by-products in the product stream are reduced.

[057] FIG. 3 is a more detailed flow diagram of portion 48 of the process of FIG. 1 for the production of HCN, in accordance with various examples. As discussed herein, after the removal of ammonia in the HCN recovery system 30 (illustrated in FIG. 1), the NH₃-stripped HCN stream 24 enter the HCN recovery system 30. The HCN recovery system 30 can contact stream 24 with water to entrain the HCN. The HCN- water mixture can be sent to a cyanide stripper where excess waste is removed from the liquid. In addition, the HCN-water mixture may also be sent through a fractionator to concentrate the HCN. The HCN product stream 32 can be stored in tanks or used directly for synthesis of other compounds.

[058] After removal of ammonia and hydrogen cyanide from an Andrussow product stream 10 (as illustrated in FIG. 1), a gaseous waste stream 34 remains that contains a variety of gases including hydrogen, unreacted methane, carbon dioxide, carbon monoxide, water, nitrogen, a variety of organonitriles, and trace amounts of HCN. The gaseous waste stream 34 should not have any detectable ammonia present. The amounts of these gases in the gaseous waste stream 34 can vary depending upon Andrussow reaction conditions. Variables that can affect the composition of the gaseous waste stream 34 include the amount of oxygen in the Andrussow reaction, the ratios of methane to ammonia, the temperature of the reactor, the catalyst effectiveness, flow rates into and through an Andrussow reactor, and the like. For example, when pure oxygen is used as a reactant in an Andrussow process and reaction conditions generally optimized, up to about 75 vol % hydrogen can be present in the gaseous waste stream, but when air is employed as a source of oxygen for the Andrussow reaction, only about 1.5 vol% hydrogen may be present in the waste product stream.

[059] The gaseous waste stream 34 can advantageously contain lower amounts of nitrogen than are present in air. For example, the gaseous waste stream 34 can contain less than about 60% nitrogen, less than about 50% nitrogen, less than about 40% nitrogen, less than about 30% nitrogen, less than about 20%, or less than about 10%.

[060] As discussed herein, an Andrussow process having an oxygen stream 6 (as illustrated in FIG. 1) that contains more than 55 vol % oxygen can produce a gaseous waste stream 34 having a heat value that enables the gaseous waste stream 34 to be burned at a temperature that can generate steam without supplementing the gaseous waste stream 34 with fuel gas. Therefore, the methods and systems disclosed herein can be particularly advantageous when the gaseous waste stream 34 includes energy rich components, such as hydrogen and carbon monoxide, that have a heat value of greater than 182 BTU/scf . For example, the methods and systems of the present disclosure can generate energy (e.g., heat and electricity) by utilizing the energy-rich components of the gaseous waste stream 34. In an example, the gaseous waste stream 34 can include about 78 vol% hydrogen and 11 vol% carbon monoxide when pure oxygen is used as the oxygen stream 6. In general, the gaseous waste stream 34 will contain only residual amounts of HCN. Removal of HCN is typically substantially complete not only so that valuable HCN is not lost to the waste water, but also for health and environmental concerns, and because significant amounts of HCN can complicate processing of the waste water.

[061] The material waste utilization system 36 can include a cogeneration unit 90. In one example, cogeneration unit 90 can include a boiler 80 and a generator 82 (e.g., an electrical generator) configured to burn the waste effluent and generate energy (e.g., heat and electricity). Other cogeneration units can be employed. In some examples, the material waste utilization system 36 can also include a water extraction unit (not shown) configured to remove liquid water from the gaseous waste stream 34 before the gaseous waste stream 34 is burned as fuel in the cogeneration unit 90.

[062] The cogeneration unit 90 can receive and burn the gaseous waste stream 34 as fuel to produce thermal energy. For example, the boiler 80 can receive and burn the gaseous waste stream 34. The heat generated from the combustion of the gaseous waste stream 34 can be contacted with water to generate heat (e.g., steam). A portion of the steam 88 can be recirculated back into the process. A portion of the steam 92 can be fed to the generator 82 to generate electricity from the thermal energy. The generator 82 can transform thermal energy into rotational energy that can produce electricity. The electricity can be used in the process 11 for producing HCN.

[063] The material waste utilization system 36 can include one or more detectors 84 configured to quantify levels of hydrogen cyanide, methane, hydrogen, carbon monoxide or a combination thereof in the gaseous waste stream 34. The material waste utilization system 36 can also include a diverter 86 to channel the gaseous waste stream 34 between the material waste utilization system 36, a hydrogen recovery system 38, and a flaring system 42. The detector 84 can monitor for energy rich components such as hydrogen and carbon monoxide. In various examples, the diverter 86 can divert the gaseous waste stream 34 from the cogeneration unit 90 when a hydrogen concentration is below a threshold value. For example, when the concentration of hydrogen is equal to or less than about 55 vol% of the gaseous waste stream 34 the diverter 86 can divert the gaseous waste stream from the cogeneration unit 90. In an example where the hydrogen concentration is equal to or less than 55 vol%, the gaseous waste stream 34 does not have a heat value that can generate steam without the addition of supplemental fuel gas. Thus, the diverter 86 can channel the gaseous waste stream 34 to the hydrogen recovery system 38 and/or the flare 42. In some examples, the diverter 86 can split the gaseous waste stream 34 such that a portion enters the cogeneration unit 90, the hydrogen recovery 38, and the flare 42, while the amount sent to the flare can be minimized.

[064] In one example where the material waste utilization system 70 is employed, the oxygen stream 6 can include more than 55 vol% oxygen. In further examples where the material waste utilization system 70 is employed, the oxygen stream 6 includes at least 65 vol % oxygen to about 100 % vol oxygen. As discussed herein, the oxygen stream 6 that includes more than 55 vol% oxygen can generate a gaseous waste stream 34 that has a heat value great enough to generate steam when burned, without supplementing the gaseous waste stream 34 with fuel gases.

[065] Various factors can determine whether the entire or a portion of the gaseous waste stream 34 is sent to the cogeneration unit 90, the hydrogen recovery 38, and or the flare 42. For example, a hydrogen demand can determine whether a portion of the gaseous waste stream 34 is sent to the hydrogen recovery 38. For example, at a minimum the portion of the gaseous waste stream 34 that is sent to the hydrogen recovery 34 should be enough to satisfy the hydrogen demand. In other examples, more of the gaseous waste stream 34 can be sent to the hydrogen recovery 38 and the recovered hydrogen can be stored. Other factors may include the cost of hydrogen, steam and electricity. For example, a cost analysis of the hydrogen recovery 38 versus the cogeneration 90 can be compared.

[066] In examples employing a flare 42, a minimum flow to the flare 42 is needed. The methods and systems of the present disclosure can minimize any amount beyond the minimum flow needed. For example, a majority of the gaseous waste stream 34 is preferentially sent to the hydrogen recovery 38, the cogeneration unit, or combinations thereof. Thus, the present methods and systems can reduce material waste by either converting the material waste into energy (e.g., heat and/or electricity) or recovering a portion of the material. In other examples, the gaseous waste stream 34 can be used as a pilot gas (not shown). Pilot gases do not require a very high heat value since it is only used to sustain a flame.

[067] In an example, a portion or the entire gaseous waste stream 34 can be channeled to the hydrogen recovery system 38. The recovered hydrogen stream 98 can be stored for future processing or sale, sent to additional hydrogen processing units, recycled to a point upstream or downstream, used to supplement a flare 42, hydro genations reactions, or combinations thereof, as discussed further below. However, if the gaseous waste stream 34 has less than about 40 vol % hydrogen, the hydrogen recovery system 42 may not be economical.

EXAMPLES

[068] The present disclosure can be better understood by reference to the following examples which are offered by way of illustration. The present disclosure is not limited to the examples given herein.

Comparative Example 1: Comparison Air and Oxygen Andrussow Process Waste Gas

Compositions

[069] This Example illustrates that an Andrussow process that uses a highly enriched source of oxygen generally produces a waste stream with higher hydrogen content than one that employs air as an oxygen source.

[070] A 4 inch internal diameter stainless steel reactor with ceramic insulation lining inside is used for pilot scale test. Forty sheets of 90 wt% Pt/10 wt% Rh 40 mesh gauze from Johnson Matthey (USA) are loaded as catalyst bed. Perforated alumina tile is used for catalyst sheet support. The total flow rate is set at 2532 SCFH (standard cubic foot per hour). Hydrogen cyanide is produced via two separate Andrussow processes. One process is an oxygen

Andrussow process that employs a gaseous reaction mixture that includes 35 vol% methane, 38 vol% ammonia and 27 vol% substantially pure oxygen. A second process is an air Andrussow process employs about 17 vol% methane, 19 vol% ammonia and 64 vol% air. A platinum- containing catalyst is used for both processes.

[071] Ammonia is separately removed from each of the product streams in a process involving absorption into an ammonium phosphate stream. Hydrogen cyanide is then removed from the ammonia-depleted product stream in a process involving acidified water, thereby separately generating a hydrogen cyanide product and a gaseous waste stream for each of the processes.

[072] The composition of the gaseous waste streams from the oxygen and air processes, after ammonia and HCN removal are shown below in Table 1. Table 1: Gaseous Waste Stream Composition

[073] As illustrated, an Andrussow process that employs highly enriched oxygen as a source of the oxygen-containing feedstream generates significantly more hydrogen than an Andrussow process that employs air as a source of the oxygen-containing feedstream.

Comparative Example 2: Waste Generated During an Oxygen Andrussow Process

[074] This Example can illustrate the amount of waste generated during production of hydrogen cyanide.

[075] Hydrogen cyanide is produced via an Andrussow process from a gaseous reaction mixture that includes 35 vol% methane, 38 vol% ammonia and 27 vol% substantially pure oxygen, in the presence of a platinum catalyst. The methane feed stream, the ammonia feed stream, and the oxygen feed stream are fed into a reactor containing a platinum catalyst. A 4 inch internal diameter stainless steel reactor with ceramic insulation lining inside is used for pilot scale test. Forty sheets of 90 wt% Pt/10 wt% Rh 40 mesh gauze from Johnson Matthey (USA) are loaded as catalyst bed. Perforated alumina tile is used for catalyst sheet support. Total flow rate is set at 2532 SCFH (standard cubic foot per hour). 1076) As the reaction proceeds a gaseous waste stream is continually produced that contains hydrogen cyanide, unreacted ammonia, waste gases and other products. After removal of the hydrogen cyanide and the unreacted ammonia, a gaseous waste stream that is free of hydrogen cyanide can contain a mixture of gases such as hydrogen, unreacted methane, carbon dioxide, carbon monoxide, water, nitrogen, a variety of organonitriles, and trace amounts of HCN, and therefore includes energy-rich gases such as hydrogen, methane and carbon monoxide. In the example, the gaseous waste stream can be sent to flare to thoroughly dispose of the components of the gaseous waste stream. In this example, approximately 40,000 scf of waste gas is produced for 1,000 lbs HCN. Additionally, 258 BTU/scf is lost after the HCN recovery.

Example 1 : Hydrogen Content in the Gaseous Waste Stream

[077] This Example illustrates how the hydrogen content of the gaseous waste stream varies in Andrussow processes using reactant oxygen-containing feedstreams with different amounts of oxygen.

[078] Hydrogen cyanide is produced via a series of separate Andrussow processes performed as described for Comparative Example 1. However, each process is performed using a different reactant oxygen-containing feedstream, where the content of oxygen in the feedstream is varied between about 20.9 vol% to about 100 vol% oxygen, as shown in Table 2.

[079] Ammonia is separately removed from each of the product streams in a process involving absorption into an ammonium phosphate stream. Hydrogen cyanide is then removed from the ammonia-depleted product stream in a process involving acidified water, thereby separately generating a hydrogen cyanide product and a gaseous waste stream for each of the processes.

[080] The composition of the gaseous waste streams from Andrussow processes run with oxygen-containing feedstreams having different oxygen contents are shown below in Table 2. Table 2:

Waste Gas Stream BTU Value as Oxygen Percentage Increases

[081] In table 2, the waste gas stream refers to the volume percent of Hydrogen in the waste stream after ammonia and HCN have been removed. Additionally, "valuable" refers to whether the waste gas stream is capable of being used as a fuel gas (e.g., combustion) to generate steam without the addition of natural gas. [082] Example 2: Oxygen Andrussow Process Utilizing an Energy Recapturing

System

[083] This Example illustrates the configuration of an energy recapturing system that includes a heat waste utilization system and a material waste utilization system operating during production of hydrogen cyanide via an oxygen Andrussow Process.

[084] A 4 inch internal diameter stainless steel reactor with ceramic insulation lining inside is used for pilot scale test. Forty sheets of 90 wt% Pt / 10 wt% Rh 40 mesh with from Johnson Matthey (USA) are loaded as catalyst bed. Perforated alumina tile is used for catalyst sheet support. The total flow rate is set at 2532 SCFH (standard cubic foot per hour). Hydrogen cyanide is produced via an Andrussow process from a gaseous reaction mixture that includes 35 vol% methane, 38 vol% ammonia and 27 vol% substantially pure oxygen, in the presence of a platinum-containing catalyst. The product stream is contacted with a cogeneration unit and generates electricity and steam. A portion of the steam can be recirculated back to preheat feedstreams of the reaction mixture to minimize an amount of externally supplied heat.

Additionally the electricity can be recirculated back into the process and minimize the amount of externally supplied electricity.

[085] As the reaction proceeds a gaseous waste stream is continually produced that contains hydrogen cyanide, unreacted ammonia, waste gases and other products. After removal of the ammonia and hydrogen cyanide a gaseous waste stream is generated. In this example, amount sent to the flare is minimized. Additionally, the gaseous waste stream has a heat value of greater than 258 BTU/scf and be sent to a cogeneration unit of a material waste utilization system. In this example, approximately 258 BTU/scf is recovered in the gaseous waste stream after the HCN recovery. During optimal operating conditions, such energy capturing units such as the heat waste utilization system and the material waste utilization system can generate greater than 100 % of the energy required for the manufacture of hydrogen cyanide by the process described.

[086] The above Detailed Description is intended to be illustrative, and not restrictive.

For example, the above-described examples (or one or more elements thereof) can be used in combination with each other. Other examples can be used, such as by one of ordinary skill in the art upon reviewing the above description. Also, various features or elements can be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter can lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[087] In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls.

[088] In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of "at least one" or "one or more." In this document, the term "or" is used to refer to a nonexclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In this document, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "including" and "comprising" are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

[089] Method examples described herein can be machine or computer-implemented, at least in part. Some examples can include a computer-readable medium or machine-readable medium encoded with instmctions operable to configure an electronic device to perform methods or method steps as described in the above examples. An implementation of such methods or method steps can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, in an example, the code can be tangibly stored on one or more volatile, non-transitory, or non- volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like. [090] The Abstract is provided to comply with 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

[091] Although the invention has been described with reference to exemplary examples, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

[092] Specific enumerated statements [1] to [31] provided below are for illustration purposes only, and do not otherwise limit the scope of the disclosed subject matter, as defined by the claims. These enumerated statements encompass all combinations, sub-combinations, and multiply referenced (e.g., multiply dependent) combinations described therein.

Statements

[093] [1.] A method of utilizing waste produced during production of hydrogen cyanide via the Andrussow process comprising:

(a) burning a gaseous waste stream for primary energy generation, wherein the gaseous waste stream is from a reactor configured to produce hydrogen cyanide, and the gaseous waste stream is substantially free of hydrogen cyanide;

(b) contacting a heat recovery unit with heat for secondary energy generation, where the heat is generated by a reactor during production of the hydrogen cyanide; or

(c) a combination thereof.

[094] [2.] The method of statement [1], wherein the primary or secondary energy generation comprises heat transfer, steam generation, electricity generation or a combination thereof.

[095] [3.] The method of statement [1] or [2], wherein the primary or secondary energy generation is steam generation and electricity generation.

[096] [4.] The method of any one of statements [l]-[3], further comprising prior to burning the gaseous waste stream, adjusting a reaction mixture comprising methane, ammonia and oxygen to provide a reaction mixture with sufficient oxygen to generate at least about 59 volume percent hydrogen in the gaseous waste stream after removal of ammonia and recovery of hydrogen cyanide.

[097] [5.] The method of statement [4], wherein the sufficient oxygen is supplied as an oxygen-containing feedstream comprising more than 55 volume percent oxygen. [098] [6.] The method of any one of statements [l]-[5], wherein the gaseous waste stream comprises about 60 volume percent oxygen to about 78 volume percent oxygen and about 10 volume percent carbon monoxide to about 15 volume percent carbon monoxide.

[099] [7.] The method of any one of statements [l]-[6], wherein the gaseous waste stream comprises less than about 50 volume percent nitrogen.

[0100] [8.] The method of any one of statements [l]-[7], wherein the gaseous waste stream comprises a heat value of greater than 182 British Thermal Unit per square cubic feet (BTU/sci).

[0101] [9.] The method of any one of statements [l]-[8], wherein the gaseous waste stream comprises a heat value of about 205 BTU/scf to about 260 BTU/scf.

[01 2] [10.] The method of any one of statements [l]-[9], wherein the gaseous waste stream is not supplemented with a fuel gas.

[0103] [11.] The method of any one of statements [1]-[10], wherein burning the gaseous waste stream includes contacting the gaseous waste stream with a first cogeneration unit.

[0104] [12.] The method of statement [11], wherein the first cogeneration unit comprises a first boiler and an electrical generator, the first boiler configured to generate steam and the electrical generator configured to generate electricity.

[0105] [13.] The method of any one of statements [1]-[12], wherein the heat recovery unit is a second cogeneration unit.

[0106] [14.] The method of statement [13], wherein the second cogeneration unit includes a second boiler and a heat-activated generator, the second boiler configured to generate steam and the heat-activated generator configured to generate electricity.

[0107] [15.] The method of statement [13], wherein contacting the heat recovery unit with heat further includes contacting a product stream from the reactor with the second cogeneration unit, wherein the product stream has a first temperature prior to contacting the second cogeneration unit and the product stream has a second temperature after contacting the second cogeneration unit, the first temperature great than the second temperature.

[0108] [16.] The method of any one of statements [1]-[15], wherein the hydrogen cyanide is produced in a reaction mixture of methane, ammonia and oxygen in the presence of a catalyst comprising platinum, wherein the reaction mixture has more than about 55 volume percent oxygen. [0109] [17.] The method of statement [16], wherein the methane is provided in a methane- containing hydrocarbon feed.

[0110] [18.] The method of statement [16] or [17], wherein the methane is provided as a hydrocarbon feed comprising natural gas, biogas, substantially pure methane or mixtures thereof.

[0111] [19.] The method of any one of statements [16]-[18], wherein the methane is provided as natural gas.

[0112] [20.] The method of any one of statements [16]-[l 9], wherein the methane is provided as substantially pure methane.

[0113] [21.] The method of any one of statements [16]-[20], wherein the oxygen is provided as an enriched-oxygen feed, a substantially pure oxygen feed, or any combination thereof.

[0114] [22.] The method of any one of statements [1]-[21], wherein ammonia has been substantially removed from the gaseous waste stream.

[0115] [23.] The method of any one of statements [l]-[22], wherein water has been

substantially removed from the gaseous waste stream.

[0116] [24.] The method of any one of statements [l]-[23], wherein the gaseous waste stream comprises hydrogen, methane or mixtures thereof.

[0117] [25.] A system for producing hydrogen cyanide via the Andrussow process, comprising:

(a) a reactor configured for producing hydrogen cyanide from a reaction mixture comprising methane, ammonia and oxygen in the presence of a catalyst comprising platinum, wherein the reactor is also configured to supply the reaction mixture with sufficient oxygen to generate a gaseous waste stream that has at least 59 hydrogen after removal of ammonia and recovery of hydrogen cyanide;

(b) a first cogeneration unit configured to burn the gaseous waste stream as a fuel for primary energy generation, wherein the gaseous waste stream is substantially free of hydrogen cyanide; and/or

(c) a second cogeneration unit configured to absorb heat from the reactor for secondary energy generation.

[0118] [26.] The system of statement [25], wherein the sufficient oxygen is supplied as an oxygen-containing feedstream comprising more than 55 volume percent oxygen. [0119] [27.] The system of any of statements [25] or [26], wherein the gaseous waste stream comprises about 60 volume percent oxygen to about 78 volume percent oxygen and about 10 volume percent carbon monoxide to about 15 volume percent carbon monoxide.

[0120] [28.] The system of any one of statements [25]-[27], wherein the gaseous waste stream comprises less than about 50 volume percent nitrogen.

[0121] [29.] The system of any one of statements [25]-[28], wherein the gaseous waste stream comprises a heat value of greater than 182 BTU/scf.

[0122] [30.] The system of any one of statements [25]-[29], wherein the gaseous waste stream comprises a heat value of about 205 BTU/scf to about 260 BTU/scf.

[0123] [31.] The system of any one of statements [25]-[30], wherein the gaseous waste stream is not supplemented with a fuel gas.

[0124] [32.] The system of any one of statements [25]-[31], further comprising:

(d) a first heat transfer system configured to absorb heat from the first cogeneration unit and recycle the heat; and/or

(e) a second heat transfer system configured to absorb heat from the second cogeneration unit and recycle the heat to warm at least one of the methane, ammonia and oxygen fed into the reactor.

[0125] [33.] The system of any one of statements [25]-[32], further comprising a detector for quantifying levels of hydrogen cyanide, methane, hydrogen, carbon monoxide or a combination thereof in the gaseous waste stream.

[0126] [34.] The system of statement [33], further comprising a valve operably linked to the detector, wherein the valve is configured divert the gaseous waste stream from the first cogeneration unit when a hydrogen concentration below a threshold value is detected in the gaseous waste stream.

[0127] [35.] The system of statement [33], further comprising a valve operably linked to the detector, wherein the valve is configured to divert the gaseous waste stream from the first cogeneration unit when a set value of combustible components is below a threshold value.

[0128] [36.] The system of statement [35], wherein the threshold value is based on a heat content value of the gaseous waste stream.

[0129] [37.] The system of statement [33], wherein the methane is a hydrocarbon feed comprising natural gas, syngas, biogas, substantially pure methane or mixtures thereof. [0130] [38]. The system of statement [33], wherein the methane is natural gas.

[0131] [39.] The system of statement [33], wherein the methane is substantially pure methane.

10132] [40]. The system of statement [33], wherein the oxygen is provided an enriched-oxygen feed, a substantially pure oxygen feed, or any combination thereof.

[0133] [41.] The system of any one of statements [25]-[40], wherein ammonia has been substantially removed from the gaseous waste stream.

[0134] [42.] The system of any of statements [25]-[41], wherein water has been substantially removed from the gaseous waste stream.

[0135] [43.] The system of any one of statements [25]-[42], wherein the waste effluent comprises hydrogen, methane or mixtures thereof.

[0136] [44.] A method, comprising:

(a) adjusting a reaction mixture comprising methane, ammonia and oxygen to provide the reaction mixture with sufficient oxygen to generate a gaseous waste stream that has at least 59 volume percent hydrogen in the gaseous waste stream after removal of ammonia and recovery of hydrogen cyanide; and

(b) burning the gaseous waste stream for energy generation.

[0137] [45.] The method of statement [44], wherein the energy generation comprises steam generation, electricity generation, or a combination thereof.

[0138] [46.] The method of statement [44], wherein the energy generation comprises steam generation and electricity generation via a cogeneration unit.

[0139] [47.] The method of any one of statements [44]-[46], wherein the sufficient oxygen is supplied as an oxygen-containing feedstream comprising more than 55 volume percent oxygen.

[0140] [48.] The method of any one of statements [44]-[47], wherein the gaseous waste stream comprises about 59 volume percent hydrogen to about 78 volume percent hydrogen, about 12 volume percent carbon monoxide to about 15 volume percent carbon monoxide, about 0.7 volume percent carbon dioxide to about 1.5 volume percent carbon dioxide, about 3 volume percent nitrogen to about 5 volume percent nitrogen, about 1 volume percent methane to about 2.0 volume percent methane, about 0.01 volume percent organonitriles to about 0.1 volume percent organonitriles, about 0.01 volume percent HCN to about 0.05 volume percent HCN, about 3 volume percent water to about 5 volume percent water, and combinations thereof. [0141] [49.] The method of any one of statements [44]-[48], wherein the gaseous waste stream comprises less than about 50 volume percent nitrogen.

[0142] [50.] The method of any one of statements [44]-[49], wherein the gaseous waste stream comprises a heat value of greater than 182 BTU/scf.

[0143] [51.] The method of any one of statements [44] -[50], wherein the gaseous waste stream comprises a heat value of about 205 BTU/scf to about 260 BTU/scf.

[0144] [52.] The method of any one of statements [44] -[51], wherein the gaseous waste stream is not supplemented with a fuel gas.

Claims

CLAIMS What is claimed is:

1. A method of utilizing waste produced during production of hydrogen cyanide via the Andrussow process comprising:

(c) a combination thereof.

2. The method of claim 1, wherein the primary or secondary energy generation comprises heat transfer, steam generation, electricity generation or a combination thereof.

3. The method of claim 1 or 2, wherein the primary or secondary energy generation is steam generation and electricity generation.

4. The method of any one of claims 1-3, further comprising:

prior to burning the gaseous waste stream, adjusting a reaction mixture comprising methane, ammonia and oxygen to provide a reaction mixture with sufficient oxygen to generate at least about 59 volume percent hydrogen in the gaseous waste stream after removal of ammonia and recovery of hydrogen cyanide.

5. The method of claim 4, wherein the sufficient oxygen is supplied as an oxygen- containing feedstream comprising more than 55 volume percent oxygen.

6. The method of any one of claims 1-5, wherein the gaseous waste stream comprises about 60 volume percent oxygen to about 78 volume percent oxygen and about 10 volume percent carbon monoxide to about 15 volume percent carbon monoxide.

7. The method of any one of claims 1-6, wherein the gaseous waste stream comprises less than about 50 volume percent nitrogen.

8. The method of any one of claims 1-7, wherein the gaseous waste stream comprises a heat value of greater than 182 British Thermal Unit per square cubic foot (BTU/scf).

9. The method of any one of claims 1-8, wherein the gaseous waste stream comprises a heat value of about 205 BTU/scf to about 260 BTU/scf.

10. The method of any one of claims 1-9, wherein the gaseous waste stream is not supplemented with a fuel gas.

11. The method of any one of claims 1-10, wherein burning the gaseous waste stream includes contacting the gaseous waste stream with a first cogeneration unit.

12. The method of claim 11, wherein the first cogeneration unit comprises a first boiler and an electrical generator, the first boiler configured to generate steam and the electrical generator configured to generate electricity.

13. The method of any one of claims 1-12, wherein the heat recovery unit is a second cogeneration unit.

14. The method of claim 13, wherein the second cogeneration unit includes a second boiler and a heat-activated generator, the second boiler configured to generate steam and the heat- activated generator configured to generate electricity.

15. The method of claim 13 , wherein contacting the heat recovery unit with heat further includes:

contacting a product stream from the reactor with the second cogeneration unit, wherein the product stream has a first temperature prior to contacting the second cogeneration unit and the product stream has a second temperature after contacting the second cogeneration unit, the first temperature great than the second temperature.

16. The method of any one of claims 1-15, wherein the hydrogen cyanide is produced in a reaction mixture of methane, ammonia and oxygen in the presence of a catalyst comprising platinum, wherein the reaction mixture has more than about 55 volume percent oxygen.

17. The method of claim 16, wherein the methane is provided in a methane-containing hydrocarbon feed.

18. The method of claim 16 or 17, wherein the methane is provided as a hydrocarbon feed comprising natural gas, biogas, substantially pure methane or mixtures thereof.

19. The method of any one of claims 16-18, wherein the methane is provided as natural gas.

20. The method of any one of claims 16-19, wherein the methane is provided as substantially pure methane.

21. The method of any one of claims 16-20, wherein the oxygen is provided as an enriched- oxygen feed, a substantially pure oxygen feed, or any combination thereof.

22. The method of any one of claims 1-21, wherein ammonia has been substantially removed from the gaseous waste stream.

23. The method of any one of claims 1 -22, wherein water has been substantially removed from the gaseous waste stream.

24. The method of any one of claims 1-23, wherein the gaseous waste stream comprises hydrogen, methane or mixtures thereof.

25. A system for producing hydrogen cyanide via the Andrussow process, comprising:

26. The system of claim 25, wherein the sufficient oxygen is supplied as an oxygen- containing feedstream comprising more than 55 volume percent oxygen.

27. The system of any of claims 25 or 26, wherein the gaseous waste stream comprises about 60 volume percent oxygen to about 78 volume percent oxygen and about 10 volume percent carbon monoxide to about 15 volume percent carbon monoxide.

28. The system of any one of claims 25-27, wherein the gaseous waste stream comprises less than about 50 volume percent nitrogen.

29. The system of any one of claims 25-28, wherein the gaseous waste stream comprises a heat value of greater than 182 BTU/scf.

30. The system of any one of claims 25-29, wherein the gaseous waste stream comprises a heat value of about 205 BTU/scf to about 260 BTU/scf.

31. The system of any one of claims 25-30, wherein the gaseous waste stream is not supplemented with a fuel gas.

32. The system of any one of claims 25-31, further comprising:

33. The system of any one of claims 25-32, further comprising a detector for quantifying levels of hydrogen cyanide, methane, hydrogen, carbon monoxide or a combination thereof in the gaseous waste stream.

34. The system of claim 33, further comprising a valve operably linked to the detector, wherein the valve is configured divert the gaseous waste stream from the first cogeneration unit when a hydrogen concentration below a threshold value is detected in the gaseous waste stream.

35. The system of claim 33, further comprising a valve operably linked to the detector, wherein the valve is configured to divert the gaseous waste stream from the first cogeneration unit when a set value of combustible components is below a threshold value.

36. The system of claim 35, wherein the threshold value is based on a heat content value of the gaseous waste stream,

37. The system of claim 33, wherein the methane is a hydrocarbon feed comprising natural gas, syngas, biogas, substantially pure methane or mixtures thereof

38. The system of claim 33, wherein the methane is natural gas.

39. The system of claim 33, wherein the methane is substantially pure methane.

40. The system of claim 33, wherein the oxygen is provided an enriched-oxygen feed, a substantially pure oxygen feed, or any combination thereof.

41. The system of any one of claims 25-40, wherein ammonia has been substantially removed from the gaseous waste stream.

42. The system of any of claims 25-41 , wherein water has been substantially removed from the gaseous waste stream.

43. The system of any one of claims 25-42, wherein the waste effluent comprises hydrogen, methane or mixtures thereof.

44. A method, comprising:

(b) burning the gaseous waste stream for energy generation.

45. The method of claim 44, wherein the energy generation comprises steam generation, electricity generation, or a combination thereof.

46. The method of claim 44, wherein the energy generation comprises steam generation and electricity generation via a cogeneration unit.

47. The method of any one of claims 44-46, wherein the sufficient oxygen is supplied as an oxygen-containing feedstream comprising more than 55 volume percent oxygen.

48. The method of any one of claims 44-47, wherein the gaseous waste stream comprises about 59 volume percent hydrogen to about 78 volume percent hydrogen, about 12 volume percent carbon monoxide to about 15 volume percent carbon monoxide, about 0.7 volume percent carbon dioxide to about 1.5 volume percent carbon dioxide, about 3 volume percent nitrogen to about 5 volume percent nitrogen, about 1 volume percent methane to about 2.0 volume percent methane, about 0.01 volume percent organonitriles to about 0.1 volume percent organonitriles, about 0.01 volume percent HCN to about 0.05 volume percent HCN, about 3 volume percent water to about 5 volume percent water, and combinations thereof.

49. The method of any one of claims 44-48, wherein the gaseous waste stream comprises less than about 50 volume percent nitrogen.

50. The method of any one of claims 44-49, wherein the gaseous waste stream comprises a heat value of greater than 182 BTU/scf.

51. The method of any one of claims 44-50, wherein the gaseous waste stream comprises a heat value of about 205 BTU/scf to about 260 BTU/scf.

52. The method of any one of claims 44-51, wherein the gaseous waste stream is not supplemented with a fuel gas.