WO2016203396A1

WO2016203396A1 - Enriching natural gas quality through hydrocarbon gas injection

Info

Publication number: WO2016203396A1
Application number: PCT/IB2016/053539
Authority: WO
Inventors: Shabbir Taherbhai LAKDAWALA; Ali Sameh AL MUTAIRI
Original assignee: Saudi Iron And Steel Company
Priority date: 2015-06-19
Filing date: 2016-06-15
Publication date: 2016-12-22

Abstract

Enriched natural gas mixtures with increased higher heating values and method of making same are disclosed. Further, an apparatus for producing direct reduced iron (DRI) is also disclose.

Description

ENRICHING NATURAL GAS QUALITY THROUGH HYDROCARBON GAS

INJECTION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/182,234, filed June 19, 2015, which is hereby incorporated by reference in its entirety.

BACKGROUND

[0002] Natural gas can be extracted from underground reservoirs and can often comprise various gaseous contaminates such as nitrogen, oxygen, and carbon dioxide. These unwanted gases can be naturally occurring and their concentration can depend on the specific drilling location. In some instances, however, nitrogen contamination can result from processing conditions, for example, nitrogen injected into the reservoir as part of an enhanced oil recovery technique. With the world economy moving towards cleaner energy sources, a 50 percent rise in global natural gas consumption has been projected to occur between 2010 and 2035. [0003] In an effort to increase production yield from natural gas wells, secondary production methods, such as gas injection, can be employed. Various gas injection techniques can boost depleted pressure in a formation. In the gas injection process, a miscible gas, for example, nitrogen, can be introduced into a well; however, the presence of nitrogen in the recovered gas stream can lower the heating value of the natural gas, increase transportation costs (based on unit heating value), and decrease production yield. For example, directed reduced iron (DRI) can be produced from the direct reduction of iron ore by reducing gas produced from natural gas. High nitrogen content in natural gas can affect the DRI formation yield. Thus, the removal of nitrogen from natural gas is of considerable importance, but current techniques for nitrogen removal are relatively expensive and can require a number of additional processing steps.

[0004] Accordingly, there remains a long-term market need for new and improved methods for increasing natural gas heating values and consequently increasing manufacturing yields natural gas. Various systems and methods useful for increasing natural gas heating values and manufacturing yields are described herein. SUMMARY OF THE INVENTION

[0005] In accordance with the purposes of the invention, as embodied and broadly described herein, the invention provides a method comprising: (a) contacting a stream of a substantially pure hydrocarbon gas with a stream of natural gas to form a mixture comprising natural gas and substantially pure hydrocarbon gas; and (b) producing a reducing gas from the mixture upon injection to direct reduction furnace, via Hydrocarbon decomposition.

[0006] In further aspects, the invention also relates to a gas mixture comprising: (a) an amount of natural gas; (b) an effective amount of a substantially pure hydrocarbon, wherein the effective amount is sufficient to produce a predetermined amount of direct reduced iron, wherein the natural gas has a higher heating value of less than about 1,000 BTU/SCF.

[0007] In yet further aspects, the invention also relates to an apparatus for producing a direct reduced iron comprising: (a) a direct reduction furnace; (b) a means for providing a stream of natural gas; (c) a means for providing a stream of substantially pure hydrocarbon; (d) a means for contacting the stream of natural gas and the stream of substantially pure hydrocarbon to form a mixture; (e) a means for producing a reducing gas from the mixture; and (f) a means for introducing the reducing gas into the direct reduction furnace.

[0008] Additional advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the aspects described below. The advantages described below will be realized and attained by means of the chemical compositions, methods, and combinations thereof particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive.

DESCRIPTION OF THE FIGURES

[0009] The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects, and together with the description, serve to explain the principles of the invention.

[0010] FIG. 1 depicts an exemplary natural gas composition (based on volume %) observed in a stream of natural gas during the years 2011- 2013.

[0011] FIG. 2 depicts exemplary fluctuations in natural gas quality expressed as higher heating values (BTU/SCF) observed during the years 2011- 2013.

[0012] FIG. 3 depicts an exemplary schematic of a natural gas enriching process.

[0013] Additional advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or can be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DETAILED DESCRIPTION [0014] Disclosed herein are materials, compounds, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are products of the disclosed method and compositions. It is to be understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds cannot be explicitly disclosed, each is specifically contemplated and described herein. This concept applies to all aspects of this disclosure including, but not limited to, steps in methods of making and using the disclosed compositions. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific aspect or combination of aspects of the disclosed methods, and that each such combination is specifically contemplated and should be considered disclosed.

1. DEFINITIONS

[0015] In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings:

[0016] As used in the specification and in the claims, the term "comprising" can include the aspects "consisting of and "consisting essentially of." Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In this specification and in the claims, which follow, reference will be made to a number of terms which shall be defined herein. [0017] As used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a hydrocarbon" includes mixtures of two or more hydrocarbons.

[0018] As used herein, the terms "about" and "at or about" mean that the amount or value in question can be the value designated some other value approximately or about the same. It is generally understood that, in one aspect, values recited are nominal values and that there can be a ±10% variation unless otherwise indicated . In another aspect, the term is intended to convey that similar values promote equivalent results or effects recited in the claims. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter, or other quantity or characteristic is "about" or "approximate" whether or not expressly stated to be such. It is understood that where "about" is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise. [0019] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent 'about,' it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independent of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as "about" that particular value in addition to the value itself. For example, if the value " 10" is disclosed, then "about 10" is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0020] The terms "first," "second," "first gas," "second gas," and the like, where used herein, do not denote any order, quantity, or importance, and are used to distinguish one element from another, unless specifically stated otherwise.

[0021] As used herein, the terms "optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0022] References in the specification and concluding claims to parts by weight, of a particular element or component in a composition or article, denote the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight of component Y, X and Y are present at a weight ratio of 2:5, and are present in such a ratio regardless of whether additional components are contained in the compound.

[0023] A weight percent ("wt %") of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included. For example, if a particular element or component in a composition or article is said to have 80% by weight, it is understood that this percentage is relative to a total compositional percentage of 100% by weight.

[0024] A volume percent ("w %" or "volume %") of a component, unless specifically stated to the contrary, is based on the total volume of all components present in the mixture or composition in which the component is included. For example, if a particular element or component in a composition is said to be present in amount about 1 volume %, it is understood that this percentage is relative to a total compositional percentage of 100% by volume.

[0025] As described herein, the terms "substantially pure" or "substantially free of contaminants" can, in various aspects, be used interchangeably and refer to a composition having less than about 10 % by weight, less than about 8 % by weight, less than about 5 % by weight, less than about 1 % by weight, less than about 0.5 % by weight, less than about 0.1 % by weight, less than about 0.05 % by weight, or less than about 0.01 % by weight of the contaminant, based on the total weight of the composition.

[0026] In other aspects, the terms "substantially pure" or "substantially free of contaminants" can refer to a composition having less than about 10 % by volume, less than about 8 % by volume, less than about 5 % by volume, less than about 1 % by volume, less than about 0.5 % by volume, less than about 0.1 % by volume, less than about 0.05 % by volume, or less than about 0.01 % by volume of the contaminant, based on the total volume of the composition. [0027] As used herein, the term "substantially," when used in reference to a composition refers, in various aspects, to a composition having more than about 90 % by weight, more than about 93 % by weight, more than about 95 % by weight, more than about 97 % by weight, more than about 99 % by weight, more than about 99.5 % by weight, or more than about 99.9 % by weight of the stated material based on the total weight of the composition. [0028] In other aspects, the term "substantially," when used in reference to a composition refers to a composition having more than about 90 % by volume, more than about 93 % by volume, more than about 95 % by volume, more than about 97 % by volume, more than about 99 % by volume, more than about 99.5 % by volume, or more than about 99.9 % by volume of the stated material based on the total volume of the composition.

[0029] As used herein, the terms "heating value" or "specific energy" are used interchangeably and refer to the heating value of specific energy of a fuel measured as the amount of heat produced by the combustion of a unit quantity of the fuel. The gross or higher heating value, or gross specific energy is the amount of heat produced by the complete combustion of a unit quantity of fuel. The gross (higher) heating value (or gross specific energy) is obtained when all products of the combustion are cooled down to the temperature present before combustion and wherein the water vapor formed during combustion is condensed. The net or lower heating value, or net specific energy is obtained by subtracting the latent heat of vaporization of water vapor formed by combustion from the gross or higher heating value (gross specific energy). For the purpose of this disclosure, and unless it is defined otherwise, "heating values" and "specific energy" can refer to gross or higher heating value (or gross specific energy) and/or to net or low heating value (or net specific energy) interchangeably. The heating value can be measured as energy released per unit mass, unit volume, or unit mole of a substance. For mixtures, the heating value can be estimated as a weighted sum.

[0030] As described herein, the term "direct reduced iron" refers to iron produced from direct reduction of iron ore by a reducing gas produced from natural gas, coal, or any other appropriate fuel. In some aspects, the process of reducing the iron ore in solid form by reducing gases is referred to as "direct reduction."

[0031] Moreover, it is to be understood that unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds true for any possible non-express basis for interpretation, including: matters of logic, with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and the number or type of aspects described in the specification.

2. REDUCING GAS MIXTURE AND A METHOD OF MAKING

[0032] The actual composition of natural gas can be dependent on the specific well location and the extraction techniques used to recover it. Natural gas is composed primary of methane, but can also comprise other gases, for example and without limitation, ethane, propane, butane, and heavier hydrocarbons. Naturally occurring small quantities of nitrogen, carbon dioxide, sulfur compounds, and water can also be found in natural gas. [0033] In some aspects, depending on the drilling location, methane can be present in natural gas in an amount from about 85 volume % to about 100 volume %, including exemplary values of about 86 volume %, about 88 volume %, about 90 volume %, about 92 volume %, about 94 volume %, about 96 volume %, about 98 volume %, and about 99 volume %. In other aspects, methane can be present in natural gas in an amount from about 99 volume % to about 100 volume %, including exemplary values of about 99.10 volume %, about 99.15 volume %, about 99.20 volume %, about 99.25 volume %, about 99.30 volume %, about 99.35 volume %, about 99.40 volume %, about 99.45 volume %, about 99.50 volume %, about 99.55 volume %, about 99.60 volume %, about 99.65 volume %, about 99.70 volume %, about 99.75 volume %, about 99.80 volume %, about 99.85 volume %, about 99.90 volume %, about 99.95 volume %, about 99.99 volume %, about 99.995 volume %, and about 99.999 volume %. In still further aspects, methane can be present in any range derived from any two values set forth above. For example and without limitation, methane can present in an amount from about 85 volume % to about 99.99 volume % or between about 99.45 volume % and about 99.999 volume %. [0034] In other aspects, natural gas can comprise from 0 volume % to about 10 volume % of ethane, including exemplary values of about 0.005 volume %, about 0.01 volume %, about 0.04 volume %, about 0.06 volume %, about 0.08 volume %, about 0.1 volume %, about 0.2 volume %, about 0.4 volume %, about 0.6 volume %, about 0.8 volume %, about 1 volume %, about 1.5 volume %, about 2 volume %, about 2.5 volume %, about 3 volume %, about 3.5 volume %, about 4 volume %, about 4.5 volume %, about 5 volume %, about 5.5 volume %, about 6 volume %, about 6.5 volume %, about 7 volume %, about 7.5 volume %, about 8 volume %, about 8.5 volume %, about 9 volume %, and about 9.5 volume %. In still further aspects, ethane can be present in any range derived from any two values set forth above. For example and without limitation, ethane can be present in an amount from about 0.02 volume % to about 9.5 volume % or between about 5 volume % and about 8 volume %.

[0035] In yet further aspects, natural gas can comprise from 0 volume % to about 5 volume % of propane, including exemplary values of about 0.0001 volume %, about 0.0005 volume %, about 0.001 volume %, about 0.005 volume %, about 0.01 volume %, about 0.04 volume %, about 0.06 volume %, about 0.08 volume %, about 0.1 volume %, about 0.2 volume %, about 0.4 volume %, about 0.6 volume %, about 0.8 volume %, about 1 volume %, about 1.5 volume %, about 2 volume %, about 2.5 volume %, about 3 volume %, about 3.5 volume %, about 4 volume %, and about 4.5 volume %. In still further aspects, propane can be present in any range derived from any two values set forth above. For example and without limitation, propane can be present in an amount from about 0.0005 volume % to about 2.5 volume % or between about 1 volume % and about 4.5 volume %.

[0036] In some aspects, natural gas can also comprise butane in an amount from 0 volume % to about 2 volume %, including exemplary values of about 0.0001 volume %, about 0.0005 volume %, about 0.001 volume %, about 0.005 volume %, about 0.01 volume %, about 0.04 volume %, about 0.06 volume %, about 0.08 volume %, about 0.1 volume %, about 0.2 volume %, about 0.4 volume %, about 0.6 volume %, about 0.8 volume %, about 1 volume %, and about 1.5 volume %. In still further aspects, butane can be present in any range derived from any two values set forth above. For example and without limitation, butane can be present in an amount from about 0.0005 volume % to about 1.5 volume % or between about 0.3 volume % and about 1 volume %.

[0037] In some aspects, natural gas can also comprise pentane in an amount from 0 volume % to about 2 volume %, including exemplary values of about 0.0001 volume %, about 0.0005 volume %, about 0.001 volume %, about 0.005 volume %, about 0.01 volume %, about 0.04 volume %, about 0.06 volume %, about 0.08 volume %, about 0.1 volume %, about 0.2 volume %, about 0.4 volume %, about 0.6 volume %, about 0.8 volume %, about 1 volume %, and about 1.5 volume %. In still further aspects, pentane can be present in any range derived from any two values set forth above. For example and without limitation, pentane can be present in an amount from about 0.0005 volume % to about 1.5 volume % or between about 0.1 volume % and about 1 volume %.

[0038] In some aspects nitrogen can be naturally present in natural gas. In other aspects, nitrogen present in natural gas is a result of gas injection performed to increase natural gas extraction. In some aspects, nitrogen can be present in an amount from 0 to about 9 volume %, including exemplary values of about 0.0001 volume %, about 0.0005 volume %, about 0.001 volume %, about 0.005 volume %, about 0.01 volume %, about 0.04 volume %, about 0.06 volume %, about 0.08 volume %, about 0.1 volume %, about 0.2 volume %, about 0.4 volume %, about 0.6 volume %, about 0.8 volume %, about 1 volume %, about 1.5 volume %, about 2 volume %, about 2.5 volume %, about 3 volume %, about 3.5 volume %, about 4 volume %, about 4.5 volume %, about 5 volume %, about 5.5 volume %, about 6 volume %, about 6.5 volume %, about 7 volume %, about 7.5 volume %, about 8 volume %, and about 8.5 volume %. In still further aspects, nitrogen can be present in any range derived from any two values set forth above. For example and without limitation, nitrogen can be present in an amount from about 0.0005 volume % to about 7 volume % or between about 7 volume % and about 8.5 volume %.

[0039] FIG.1 demonstrates fluctuations in a natural gas composition measured over time in one exemplary well location . It can be seen that the amount of nitrogen (curve 3, FIG.l) in the natural gas increased significantly over the last five years. It can be also seen that natural gas produced at this location also contains carbon dioxide (curve 2, FIG.l).

[0040] In some aspects, the presence of nitrogen in an amount from about 0.0001 volume % to about 9 volume % can result in a significant decrease of higher heating values of natural gas. In some aspects, the higher heating value of the produced natural gas can be in the range from about 850 BTU/SCF to about 1, 100 BTU/SCF, including exemplary values of about 860 BTU/SCF, about 870 BTU/SCF, about 880 BTU/SCF, about 890 BTU/SCF, about 900 BTU/SCF, about 910 BTU/SCF, about 920 BTU/SCF, about 930 BTU/SCF, about 940 BTU/SCF, about 950 BTU/SCF, about 960 BTU/SCF, about 970 BTU/SCF, about 980 BTU/SCF, about 990 BTU/SCF, about 1,000 BTU/SCF, about 1,020 BTU/SCF, about 1,040 BTU/SCF, about 1,060 BTU/SCF, and about 1,080 BTU/SCF. In still further aspects, the higher heating value of the produced natural gas can be in any range derived from any two values set forth above. For example and without limitation, the higher heating value of the produced natural gas can be from about 850 BTU/SCF to about 1,000 BTU/SCF or between about 930 BTU/SCF and about 990 BTU/SCF.

[0041] FIG.2 demonstrates the changes in the higher heating value of natural gas produced at an exemplary well location. As illustrated in FIGS. l and 2, the higher heating value of natural gas produced at this exemplary well location decreased significantly with increasing nitrogen content.

[0042] The higher heating value of natural gas is an important parameter that can be used to measure efficiency and the cost of many industrial processes. In various exemplary aspects, natural gas can be used in the iron making industry. In one aspect, natural gas can be used in direct iron production. In these exemplary aspects, oxygen is removed from iron by a reducing gas. In one aspect, the reducing gas used in the process can be generated from natural gas. In some aspects, the reducing gas comprises a mixture of hydrogen and carbon monoxide that can act as a reducing agent. The reducing agent reduces the iron ore in a solid form forming a direct reduced iron or DRI.

[0043] The energy consumed in a natural gas based DRI production process depends on the higher heating values of the natural gas and can be in the range of about 10 to about 11.5 MMBTU/MT. In some aspects, about 40-50 % of the total energy can be utilized for the reduction of oxygen and carbon addition in a DRI process. In some aspects, about 40-50 % of the total energy can be utilized for the reduction of metal in a DRI process. In other aspects, about 15-25 % of the total energy can be utilized to drive thermal kinetics of the reduction reaction. In yet other aspects, about 25- 40 % of the total energy can be utilized in a reformer for reforming and the thermal kinetics associated with a reforming process. It should be understood that an increase in the higher heating value of natural gas can result in a higher production yield of DRI.

[0044] In various aspects described herein, the higher heating value of natural gas can be increased without utilizing expensive nitrogen separation techniques or the introduction of any additional processing step to remove nitrogen from the natural gas stream. In one aspect, the higher heating value can be increased using a method comprising contacting a stream of substantially pure hydrocarbon gas with a stream of natural gas to form a mixture comprising natural gas and the substantially pure hydrocarbon gas. In another aspect, the mixture comprising natural gas and the substantially pure hydrocarbon gas can be further utilized by producing a reducing gas from the mixture. In some aspects, the reducing gas produced from the mixture can be further utilized to produce a direct reduced iron (DRI). FIG. 3 shows exemplary schematics of the method 100 described herein. The stream of natural gas 102 is provided from any available source. The stream of substantially pure hydrocarbon 104 is injected into the stream of natural gas 102 at an injection point 106 to form a mixture of natural gas and substantially pure hydrocarbon gas 110. Any excess or unused hydrocarbon gas can continue in a separate stream 108. In some aspects, the mixed gas supply 110 can be further utilized to produce a reducing gas.

[0045] In some aspects, production of the reducing gas comprises reforming the mixture comprising natural gas and substantially pure hydrocarbon gas. In one aspect, the reforming process comprises forming hydrogen and elemental carbon via cracking of hydrocarbons present in the mixture of natural gas and substantially pure hydrocarbon gas. In one aspect, the reforming process comprises forming hydrogen and carbon monoxide via cracking of hydrocarbons present in the mixture of natural gas and substantially pure hydrocarbon gas. In some aspects, reforming the mixture can occur in a furnace configured to produce DRIs. In another aspect, the reforming process comprises the catalytic decomposition of hydrocarbons present in the mixture over a catalyst. In yet another aspect, the catalyst can comprise nascent iron present in the furnace. In a further aspect, a catalyst, if used, can comprise Fe⁺² that is a product of the iron reduction.

[0046] In some aspects, reforming of the mixture of natural gas and substantially pure hydrocarbon results in the formation of hydrogen gas and carbon. In other aspects, carbon formed during the reforming process can react with iron to form ferric carbides. Without being bound by a specific theory, it is hypothesized that ferric carbide formation can further boost direct reduced iron carbon content. In still further aspects, direct reduced iron with increased carbon content in the bound form can be further utilized in various steel processes.

[0047] In some aspects, the stream of substantially pure hydrocarbon gas can comprise at least one of ethane, propane, and/or butane. In one aspect, the stream of substantially pure hydrocarbon gas comprises ethane. In yet another aspect, the stream of substantially pure hydrocarbon gas comprises propane. In a yet further aspect, the stream of substantially pure hydrocarbon gas comprises butane. In certain aspects, the stream of substantially pure hydrocarbon comprises a mixture of substantially pure ethane and propane.

[0048] In some aspects, the stream of substantially pure hydrocarbon can comprise some amounts of hydrocarbons that are different from the substantially pure hydrocarbon gas. In one exemplary aspect, wherein the stream of substantially pure hydrocarbon comprises propane, the stream can also comprise ethane, butane, or a combination thereof. In yet another exemplary aspect, ethane, butane, or a combination thereof can be present in propane in an amount up to about 10 volume % of the total volume of the stream of substantially pure hydrocarbon gas, including exemplary values up to about 1 volume %, up to about 2 volume %, up to about 3 volume %, up to about 4 volume %, up to about 5 volume %, up to about 6 volume %, up to about 7 volume %, up to about 8 volume %, and up to about 9 volume %. In other aspects, ethane can be present in any proportion to butane, wherein the combination of ethane and butane is up to about 10 volume % the total volume of the stream of substantially pure hydrocarbon gas.

[0049] In other exemplary aspects, wherein the stream of substantially pure hydrocarbon comprises butane, the stream can also comprise ethane, propane, or a combination thereof. In yet another exemplary aspect, ethane, propane, or a combination thereof can be present in butane in an amount up to about 10 volume % of the total volume of the stream of substantially pure hydrocarbon gas, including exemplary values up to about 1 volume %, up to about 2 volume %, up to about 3 volume %, up to about 4 volume %, up to about 5 volume %, up to about 6 volume %, up to about 7 volume %, up to about 8 volume %, and up to about 9 volume %. In other aspects, ethane can be present in any proportion to propane, wherein the combination of ethane and butane is up to about 10 volume % the total volume of the stream of substantially pure hydrocarbon gas.

[0050] In some aspects, the stream of substantially pure hydrocarbon gas has a higher heating value of in the range from at least about 1,000 BTU/SCF to about 3,500 BTU/SCF, including exemplary values of about 1,100 BTU/SCF, about 1,200 BTU/SCF, about 1,300 BTU/SCF, about 1,400 BTU/SCF, about 1,500 BTU/SCF, about 1,600 BTU/SCF, about 1,700 BTU/SCF, about 1,800 BTU/SCF, about 1,900 BTU/SCF, about 2,000 BTU/SCF, about 2,100 BTU/SCF, about 2,200 BTU/SCF, about 2,300 BTU/SCF, about 2,400 BTU/SCF, about 2,500 BTU/SCF, about 2,600 BTU/SCF, about 2,700 BTU/SCF, about 2,800 BTU/SCF, about 2,900 BTU/SCF, about 3,000 BTU/SCF, about 3, 100 BTU/SCF, about 3,200 BTU/SCF, about 3,300 BTU/SCF, and about 3,400 BTU/SCF. In still further aspects, the higher heating value of the stream of substantially pure hydrocarbon gas can be in any range derived from any two values set forth above. For example and without limitation, the higher heating value of the stream of substantially pure hydrocarbon gas can be at least 1,000 BTU/SCF, from about 1,500 BTU/SCF to about 3,000 BTU/SCF or between about 1,700 BTU/SCF and about 3,200 BTU/SCF.

[0051] In some aspects, the methods described herein are directed to increasing the higher heating value of natural gas. In one aspect, the substantially pure hydrocarbon gas is contacted with the stream of natural gas to increase the higher heating value of the natural gas. In another aspect, an effective amount of substantially pure hydrocarbon gas contacted with the stream of natural gas is equal to an amount of substantially pure hydrocarbon gas needed to bring a higher heating value of the mixture to at least about 1,000 BTU/SCF. In other aspects, an effective amount of substantially pure hydrocarbon gas contacted with the stream of natural gas is equal to an amount of substantially pure hydrocarbon gas needed to bring a higher heating value of the mixture to at least about 1,000 BTU/SCF to about 2,000 BUT/SCF, including exemplary values of about 1, 100 BTU/SCF, about 1,200 BTU/SCF, about 1,300 BTU/SCF, about 1,400 BTU/SCF, about 1,500 BTU/SCF, about 1,600 BTU/SCF, about 1,700 BTU/SCF, about 1,800 BTU/SCF and about 1,900 BTU/SCF. In still further aspects, an effective amount of substantially pure hydrocarbon gas contacted with the stream of natural gas a can be in any range derived from any two values set forth above. One of ordinary skill in the art, in possession of this disclosure, would be able to determine an effective amount of substantially pure hydrocarbon gas.

[0052] In some aspects, the gas mixture formed as a result of contacting a stream of substantially pure hydrocarbon with a stream of natural gas can have a higher heating value of at least about 1,000 BTU/SCF. In another aspects, the gas mixture formed as a result of contacting a stream of substantially pure hydrocarbon with a stream of natural gas can have a higher heating value of at least about 1,000 BTU/SCF to about 2,000 BUT/SCF, including exemplary values of about 1, 100 BTU/SCF, about 1,200 BTU/SCF, about 1,300 BTU/SCF, about 1,400 BTU/SCF, about 1,500 BTU/SCF, about 1,600 BTU/SCF, about 1,700 BTU/SCF, about 1,800 BTU/SCF and about 1,900 BTU/SCF. In still further aspects, an amount of substantially pure hydrocarbon gas contacted with the stream of natural gas can be in any range derived from any two values set forth above.

[0053] In some other aspects, the stream of substantially pure hydrocarbon can be provided in an excess amount. In yet another aspect, the excess amount of the substantially pure hydrocarbon can be further utilized in any process known to someone skilled in the art.

[0054] In yet further aspects, the gas mixture formed by the invention method can comprise one or more of methane, ethane, propane, butane, pentane, carbon dioxide, or nitrogen.

[0055] In some aspects, the gas mixture of the current invention can be utilized in the direct reduction of iron. In yet other aspects, an effective amount of substantially pure hydrocarbon gas contacted with the stream of natural gas is effective to an amount off substantially pure hydrocarbon gas needed to increase a direct reduced iron yield about 5 to about 10 % when compared to a direct reduced iron yield produced without contacting the substantially pure hydrocarbons with natural gas, including exemplary values of about 5. 2 %, about 5.5 %, about 5.8%, about 6 %, about 6.2 %, about 6.5 %, about 6.8 %, about 7 %, about 7.2 %, about 7.5 %, about 7.8 %, about 8 %, about 8.2 %, about 8.5 %, about 8.8 %, about 9 %, about 9.2 %, about 9.5 %, and about 9.8 %. In still further aspects, the increase in a direct reduced iron yield can be in any range derived from any two values set forth above. For example and without limitation, the increase in a direct reduced iron yield can be about 5 % to about 8 %, or about 7 % to about 10 % when compared to a direct reduced iron yield produced without contacting the substantially pure hydrocarbons with natural gas. 3. APPARATUS

[0056] In certain aspects, disclosed herein is an apparatus for producing a direct reduced iron, the apparatus comprising: (a) a direct reduction furnace and (b) at least one mixing and/or proportioning valve to form a mixture from the stream of natural gas and the stream of substantially pure hydrocarbon.

[0057] In one aspect and without limitation, the direct reduction furnace can comprise any furnace known in the art capable of directly reducing iron. In another aspect, the direct reduction furnace can comprise a blast furnace (BF), an electric arc furnace (EAF), or a combination thereof. In other aspects, a stream of natural gas can be provided using conventional piping and delivery equipment common in the industry. In another aspect, one or more of a mixer, flow controller, atmosphere controller, pressure controller, temperature controller, or a combination thereof can optionally be utilized to control the flow of the natural gas stream, the substantially pure hydrocarbon gas stream, or both streams.

[0058] In other aspects, the apparatus can further comprise one or more of a catalyst, mixer, furnace, temperature controller, pressure controller, flow controller, composition controller, outlet for introducing and removing components, outlet for precipitated components, and/or any combinations or equivalents thereof, for producing a reducing gas from the mixture of natural gas and substantially pure hydrocarbon gas.

[0059] In certain aspects, disclosed herein is an apparatus for producing a direct reduced iron, the apparatus comprising: (a) a direct reduction furnace; (b) a means for providing a stream of natural gas; (c) a means for providing a stream of substantially pure hydrocarbon; d) a means for contacting the stream of natural gas and the stream of substantially pure hydrocarbon to form a mixture; (e) a means for producing reducing gas from the mixture; and (f) a means for introducing the reducing gas into the direct reduction furnace.

[0060] In one aspect and without limitation, the direct reduction furnace can comprise any furnace known in the art capable of directly reducing iron. In another aspect, the direct reduction furnace can comprise a blast furnace (BF), an electric arc furnace (EAF), or a combination thereof. In other aspects, a means for providing a stream of natural gas can comprise any means available in the industry, including but not limited to pipes, tubes, containers, or any combinations thereof.

[0061] In yet another aspect, the means for providing a stream of natural gas can be equipped with accessories allowing the efficient delivery of a stream of natural gas, for example and without limitation, a means for providing a stream of natural gas can be equipped with mixers, flow controllers, atmosphere controllers, pressure controllers, temperature controllers, , or any combinations thereof. [0062] In certain aspects, a means for providing a stream of a substantially pure hydrocarbon can comprise any means available in the industry, including but not limited to pipes, tubes, containers, or any combinations thereof. In yet another aspect, the means for providing a stream of a substantially pure hydrocarbon gas can be equipped with accessories allowing the efficient delivery of a stream of natural gas, for example and without limitation, the means for providing a stream of a substantially pure hydrocarbon can be equipped with mixers, flow controllers, atmosphere controllers, pressure controllers, temperature controllers, or any combinations thereof.

[0063] In some aspects, the apparatus described herein comprises a means for contacting the stream of natural gas and the stream of a substantially pure hydrocarbon to form a mixture. In other aspects, the means for contacting can comprise but are not limited to pipes, tubes, containers, chambers, or any combination or equivalent of. In yet another aspect, the means for contacting can further comprise mixers, temperature controllers, gas controllers, flow controllers, composition controllers, expanders, reducers, or any combinations or equivalents thereof. [0064] In certain aspects, the apparatus can further comprise a means for producing a reducing gas from the mixture. In some aspects, the means for producing the reducing gas can comprise catalysts, mixers, furnaces, temperature controllers, pressure controllers, flow controllers, composition controllers, outlets for introducing and removing components, outlets for precipitation of possible components, or any combinations or equivalents thereof. [0065] In some aspects, the apparatus can further comprise a means for introducing the reducing gas into the direct reduction furnace. In other aspects, the means for introducing the reducing gas into the direct reduction furnace can comprise, but are not limited to, pipes, tubes, containers, chambers, or any combination or equivalent of. In yet other aspects, the means for introducing the reducing gas into the direct reduction furnace can further comprise mixers, temperature controllers, gas controllers, flow controllers, composition controllers, expanders, reducers, or any combinations or equivalents thereof.

[0066] In yet in another aspect, described herein is an apparatus comprising a direct reduction furnace, a line configured for providing a stream of natural gas, a line configured for providing a stream of substantially pure hydrocarbon; a chamber configured for contacting the stream of natural gas and the stream of substantially pure hydrocarbon to form a mixture; a chamber configured for producing a reducing gas from the mixture; and a line for introducing the reducing gas into the direct reduction furnace. In some aspects, the term "a line configured for" can be defined by pipes, tubes, containers, chambers, or any combination or equivalents thereof. In yet another aspect, "a line configured for" can be further defined by the presence of mixers, temperature controllers, gas controllers, flow controllers, composition controllers, expanders, reducers, or any combinations or equivalents thereof. In yet another aspect, the terms "chamber" and "a line configured for" can be used interchangeably.

[0067] The present invention is further defined in the following Examples, in which all parts and percentages are by volume unless otherwise stated. It should be understood that these examples, are given by way of illustration only and are not to be construed as limiting in any manner. From the above discussion and these examples, one skilled in the art can ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.

EXAMPLES

Example 1

[0068] The gross energy requirements needed for the production of a MT of DRI is 2.75 Gcal/MT DRI, with ± 5% variation depending on plant and seasonal conditions that equals to the gross energy equivalent of 10.91 MMBTU/MT DRI. The compositions and heating values of natural gas and ethane used as a substantially pure hydrocarbon forming the mixture are presented in Table 1.

Table 1. Ethane addition to natural gas to increase higher heating values of natural gas.

[0069] The compositions and heating values of natural gas and propane used as a substantially pure hydrocarbon forming the mixture are presented in Table 2.

Table 2. Propane addition to natural gas to increase higher heating values of natural gas.

[0070] Those skilled in the art will appreciate that numerous changes and modifications may be made to the preferred embodiments of the invention and that such changes and modifications may be made without departing from the spirit of the invention. It is, therefore, intended that the appended claims cover all such equivalent variations and fall within the true spirit and scope of the invention.

ASPECTS

[0071] In view of the described gas compositions, apparatuses, methods, and variations thereof, herein below are detailed aspects of the invention. These particularly recited aspects should not, however, be interpreted to have any limiting effect on claims containing different or more general teachings described herein, or that the "particular" aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.

[0072] Aspect 1 : A method comprising:

(a) contacting a stream of a substantially pure hydrocarbon gas with a stream of natural gas to form a mixture comprising natural gas and substantially pure hydrocarbon gas; and

(b) producing a reducing gas from the mixture.

[0073] Aspect 2: The method of Aspect 1, wherein a step of producing the reducing gas comprises reforming the mixture comprising natural gas and substantially pure hydrocarbon gas.

[0074] Aspect 3 : The method of any one of Aspects 1-2, further comprising reducing an iron ore comprising iron oxide by using the reducing gas to produce a direct reduced iron.

[0075] Aspect 4: The method of any one of Aspects 1-3, wherein the stream of natural gas has a higher heating value in the range from about 850 to about 1,000 BTU/SCF.

[0076] Aspect 5: The method of any one of Aspects 1-4, wherein no nitrogen purification step is performed prior to step a) or b).

[0077] Aspect 6: The method of any one of Aspects 1-5, wherein nitrogen is present in the stream of natural gas in an amount of at least 3 volume % based on the total volume of natural gas composition.

[0078] Aspect 7: The method of any one of Aspects 1-6, wherein the stream of substantially pure hydrocarbon gas has a higher heating value of at least about 1,000 BTU/SCF.

[0079] Aspect 8: The method of any one of Aspects 1-7, wherein the stream of substantially pure hydrocarbon gas has a higher heating value in the rage from about 1,500 BTU/SCF to about 3,000 BTU/SCF. [0080] Aspect 9: The method of any one of Aspects 1-8, wherein the stream of substantially pure hydrocarbon gas comprises at least one of ethane, propane, or butane.

[0081] Aspect 10: The method of any one of Aspects 1-9, wherein the stream of substantially pure hydrocarbon gas is ethane.

[0082] Aspect 11 : The method of any one of Aspects 1-10, wherein the stream of substantially pure hydrocarbon gas is propane.

[0083] Aspect 12: The method of any one of Aspects 1-11, wherein the stream of substantially pure hydrocarbon gas comprises a mixture of substantially pure ethane and propane.

[0084] Aspect 13 : The method of any one of Aspects 1-12, wherein an effective amount of substantially pure hydrocarbon gas contacted with the stream of natural gas is equal to an amount of substantially pure hydrocarbon gas needed to bring a higher heating value of the mixture to at least 1,000 BTU/SCF.

[0085] Aspect 14: The method of any one of Aspects 1-13, wherein the mixture comprising natural gas and substantially pure hydrocarbon gas has a higher heating value of at least about 1,000 BTU/SCF.

[0086] Aspect 15: The method of any one of Aspects 1-14, wherein an effective amount of substantially higher hydrocarbon gas contacted with the stream of natural gas is equal to an amount of substantially pure hydrocarbon gas needed to increase a direct reduced iron yield about 5 to about 10 % when compared to a direct reduced iron yield produced without contacting the substantially pure hydrocarbons with natural gas.

[0087] Aspect 16: A gas mixture comprising:

(a) an amount of natural gas;

(b) an effective amount of a substantially pure hydrocarbon, wherein the effective amount is sufficient to produce a predetermined amount of direct reduced iron, wherein natural gas has a higher heating value of less than about 1,000 BTU/SCF. [0088] Aspect 17: The gas mixture of Aspect 16, wherein the mixture has a higher heating value of at least 1,000 BTU/SCF.

[0089] Aspect 18: The gas mixture of any one of Aspects 16-17, wherein natural gas comprises one or more of methane, ethane, propane, butane, pentane, carbon dioxide, or nitrogen.

[0090] Aspect 19: The gas mixture of any one of Aspects 16-18, wherein natural gas comprises nitrogen in an amount of at least 3 volume % based on the total volume of natural gas.

[0091] Aspect 20: An apparatus for producing a direct reduced iron comprising:

(a) a direct reduction furnace;

(b) means for providing a stream of natural gas;

(c) means for providing a stream of substantially pure hydrocarbon;

(d) means for contacting the stream of natural gas and the stream of substantially pure hydrocarbon to form a mixture;

(e) means for producing a reducing gas from the mixture; and

(f) means for introducing the reducing gas into the direct reduction furnace.

Claims

1. A method comprising:

(b) producing a reducing gas from the mixture.

2. The method of claim 1, wherein a step of producing the reducing gas comprises

reforming the mixture comprising natural gas and substantially pure hydrocarbon gas.

3. The method of claim 1, further comprising reducing an iron ore

comprising iron oxide by using the reducing gas to produce a direct reduced iron.

4. The method of claim 1, wherein the stream of natural gas has a higher heating value in the range from about 850 to about 1,000 BTU/SCF.

5. The method of claim 1, wherein no nitrogen purification step is performed prior to step a) or b).

6. The method of claim 1, wherein nitrogen is present in the stream of natural gas in an amount of at least 3 volume % based on the total volume of natural gas composition.

7. The method of claim 1, wherein the stream of substantially pure hydrocarbon gas has a higher heating value of at least about 1,000 BTU/SCF.

8. The method of claim 7, wherein the stream of substantially pure hydrocarbon gas has a higher heating value in the rage from about 1,500 BTU/SCF to about 3,000

BTU/SCF.

9. The method of claim 1, wherein the stream of substantially pure hydrocarbon gas comprises at least one of ethane, propane, or butane.

10. The method of claim 1, wherein the stream of substantially pure hydrocarbon gas is ethane.

11. The method of claim 1, wherein the stream of substantially pure hydrocarbon gas is propane.

12. The method of claim 1, wherein the stream of substantially pure hydrocarbon gas comprises a mixture of substantially pure ethane and propane.

13. The method of claim 1, wherein an amount of substantially pure hydrocarbon gas contacted with the stream of natural gas is equal to an amount of substantially pure hydrocarbon gas needed to bring a higher heating value of the mixture to at least 1,000 BTU/SCF.

14. The method of claim 1, wherein the mixture comprising natural gas and substantially pure hydrocarbon gas has a higher heating value of at least about 1,000 BTU/SCF.

15. The method of claim 1, wherein an amount of substantially pure hydrocarbon gas contacted with the stream of natural gas is equal to an amount of substantially pure hydrocarbon gas needed to increase a direct reduced iron yield about 5 to about 10 % when compared to a direct reduced iron yield produced without contacting the substantially pure hydrocarbons with natural gas.

16. A gas mixture comprising:

(a) an amount of natural gas;

(b) an effective amount of a substantially pure hydrocarbon, wherein the effective amount is sufficient to produce a predetermined amount of direct reduced iron, wherein natural gas has a higher heating value of less than about 1,000 BTU/SCF.

17. The gas mixture of claim 16, wherein the mixture has a higher heating value of at least 1,000 BTU/SCF.

18. The gas mixture of claim 16, wherein natural gas comprises one or more of methane, ethane, propane, butane, pentane, carbon dioxide, or nitrogen.

19. The gas mixture of claim 18, wherein natural gas comprises nitrogen in an amount of at least 3 volume % (maximum 9%, nominal 7%-8%) based on the total volume of natural gas.

20. An apparatus for producing a direct reduced iron comprising:

(a) a direct reduction furnace;

(b) means for providing a stream of natural gas;

(c) means for providing a stream of substantially pure hydrocarbon;

(e) means for producing a reducing gas from the mixture; and

(f) means for introducing the reducing gas into the direct reduction furnace.