Patent Publication Number: US-2018030361-A1

Title: Enhanced fuels, methods of producing enhanced fuels, and additives for mitigating corrision

Description:
TECHNICAL FIELD 
     The present disclosure relates to enhanced fuels suitable for use in internal combustion engines. Moreover, the present disclosure is concerned with methods of producing such enhanced fuels. Furthermore, the present disclosure is concerned with compounds as additives for alcohol-based fuels to mitigate corrosion. 
     BACKGROUND 
     Combustion systems such as internal combustion engines are well known. In such combustion systems, combustible hydrocarbon fuels such as diesel oil are oxidized by air to generate hot gases that are used to generate mechanical power, for example for transportation purposes. However, such combustion in air generates as by-products carbonaceous soot particles and Nitrogen oxides (NO x ). Several innovations reduce and/or filter such soot particles and Nitrogen oxides (NO x ) in exhaust gases from combustion systems, for example by spraying Urea solution, namely “AdBlue”, into vehicle engine exhaust systems. However, such additional chemicals required for spraying into exhaust systems complicates vehicle systems and also adds to operating costs. 
     Contemporary combustion fuels are derived, namely manufactured, from geological fossil reserves. Such fossil reserves are of finite capacity and are being gradually exhausted, as the present World consumption of oil is in an order of 100 million barrels of oil per day. More recently, there is a growing interest in biofuels derived from contemporary biota. The use of biofuel as a motor fuel has been studied in detail already since the 20th Century. In a recent period, alternative fuels, in contradistinction to conventional fossil-reserve-derived fuels, is used as a motor fuel, or an addition to basic fuel, in many countries, such as Brazil, Germany, Sweden and USA [1]. Technologies have been developed for producing motor fuels including plain ethanol, as well as its blends with regular gasoline and diesel fuel to be used in internal combustion engines. Significant innovations relating to alternative fuels are described in patent documents WO2009/106647, U.S. Pat. No. 5,628,805 and DE10339355. 
     One such example includes methanol, which can be used as an alcohol-based fuel. Methanol as a combustion fuel provides various advantages, as follows:
         1. less particulate emissions during combustion;   2. lower NOx compared with other IC fuels;   3. has virtually no sulphur content;   4. has a high octane value; and   5. can be made from a vast variety of biomasses and mixed with methanol made from fossil fuels.       

     But, methanol as an alcohol-based fuel is corrosive. Therefore, use of methanol as a combustion fuel can cause wear and tear in an internal combustion engine due to its poor anti-corrosive property. Generally, the corrosion promoting compounds present in the crankcase are principally weak organic acids which may result from nitration and/or oxidation due to contamination by blow-by gases and exposure of the lubricant to high temperatures. For the purpose of preventing corrosivity by these compounds on the various engine parts, it is necessary to incorporate dispersants, detergents, and corrosion inhibitors in the lubricating oil or fuel composition. 
     Corrosion inhibitors are known in the prior art. In spite of much advancement in the field of corrosion science and technology, the phenomenon of corrosion (mainly of Fe, Al, Cu, Zn, Mg and their alloys) remains a major concern to industries around the world. Though the serious consequences of corrosion can be controlled to a great extent by selection of highly corrosion resistant materials, the cost factor associated with the same, favours the use of cheap metallic materials along with efficient corrosion prevention methods in many industrial applications. In this aspect, corrosion inhibitors have ample significance as individual inhibitors or as a component in chemical formulations. 
     For instance, U.S. Pat. No. 4,214,876 discloses a corrosion inhibitor for hydrocarbon fuels comprising a polymerized unsaturated aliphatic carboxylic acid having about 16-18 carbon atoms and a monoalkenyl succinic acid wherein the alkenyl group contains 8-18 carbon atoms. 
     U.S. Pat. No. 4,426,208 discloses a corrosion inhibitor for gasohol comprising at least one polymerized unsaturated aliphatic carboxylic acid having from about 16 to 18 carbon atoms per molecule and an aliphatic dicarboxylic acid having from 2 to about 10 carbon atoms. U.S. Pat. No. 4,440,545 discloses a corrosion inhibitor for gasohol comprising a hydrocarbyl succinic acid or anhydride having from about 8-30 carbon atoms. 
     However, the efficacy, convenience, and cost effectiveness of corrosion inhibitors with respect to timeframe, emulsification, interaction with subsequent processes and safety issues still remains a concern. 
     Further, when it comes to alcohol-based fuel being used as combustion fuel, the issues of poor anti-corrosive property of such alcohol-based fuel still remains a challenge. 
     Thus there still exists a need for alcohol-based fuel, such as methanol, to have improved anti-corrosive property. 
     SUMMARY 
     The present disclosure seeks to provide an enhanced fuel, for example an enhanced fuel which is based upon methanol. 
     Further, the present disclosure seeks to provide alcohol-based fuel, such as methanol-based fuel, with improved anti-corrosive property. 
     Furthermore, the present disclosure seeks to provide a method of producing the aforesaid enhanced fuel. 
     Moreover, the present disclosure seeks to provide additives for fuels, which, when added to the fuels, is capable of enhancing the fuels. 
     According to a first aspect, there is provided a fuel for use in internal combustion engines, wherein the fuel includes a mixture of at least one alcohol:
     (i) at least one alcohol, wherein the at least one alcohol includes methanol;   (ii) Ammonium Nitrate in a concentration having a range of 0.5-10 weight %;   (iii) urea in a concentration having a range of 1-10 weight %; and   (iv) water to dissolve the Ammonium Nitrate and Urea in the at least one alcohol.   

     The fuel, based on above aspects, is of advantage is that an addition of water renders Ammonium Nitrate and/or urea co-soluble in at least one alcohol, for example methanol, thereby providing a solution which is stable in storage, and also useable directly as a substitute for fuels such as diesel, petrol, kerosene and other heavy fuel oils. 
     More optionally, for the fuel, the Ammonium Nitrate is included in a concentration having a range of 1-5 weight %. 
     According to another aspect, there is provided a method of producing a fuel, wherein the method includes:
     (i) Mixing at least one alcohol, Ammonium Nitrate in a concentration having a range of 0.5-10 weight % and urea in a concentration having a range of 1-10 weight %, wherein the at least one alcohol is methanol; and   (ii) During mixing in (i), adding water so that the Ammonium Nitrate and urea becomes dissolvable in the at least one alcohol.   

     More optionally, in the method, the Ammonium Nitrate is included in a concentration having a range of 1-5 weight %. 
     According to yet another aspect, there is provided a fuel additive including a mixture of Ammonium Nitrate, urea and water, for use in at least one alcohol based fuel, wherein the at least one alcohol is methanol included in a concentration having a range of 90-97 weight %, wherein the urea is included in a concentration having a range of 1-10 weight %, wherein the Ammonium Nitrate is included in a concentration having a range of 0.5-10 weight %, and wherein the water is included in a quantity which renders the Ammonium Nitrate and urea dissolved in the at least one alcohol. 
     It will be appreciated that features of the invention are susceptible to being combined in various combinations without departing from the scope of the invention as defined by the appended claims. 
    
    
     
       DESCRIPTION OF THE DIAGRAMS 
       Embodiments of the present invention will now be described, by way of example only, with reference to the following diagrams wherein: 
         FIGS. 1 and 2  are graphical illustration of enhanced fuel pursuant to the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS OF THE DISCLOSURE 
     In recent years, current environmental laws and society pressure have placed less emphasis on economics of fuels, and more on environmental gains. 
     Nevertheless, an additive that costs less, and makes an overall combustion process in internal combustion engines more efficient will increase economic benefits, which associated to intrinsic environmental gains, makes alcohol once more an attractive alternative to diesel fuel from a commercial perspective. 
     In overview, the present disclosure is concerned with an enhanced fuel which is based upon an alcohol, for example ethanol and/or methanol, which is economical to produce, and which can be used as a diesel fuel substitute, with only minor changes being necessary to an internal combustion diesel fuel engine. 
     As is well known in the art, fuel compositions typified by methanol and/or alcohols must possess low corrosion activity; and this is usually effected by the addition of various corrosion inhibition systems. Corrosion inhibitors intended for use in fuel systems must be effective in very small quantities so as to avoid adverse effects and so as to minimize costs. 
     In the present disclosure, there is proposed a fuel additive and a combination of fuel additives particularly characterized by corrosion inhibition, ease of use and cost-effectiveness. 
     In an embodiment of the present disclosure, in an additive composition, urea is employed as a corrosion inhibitor for methanol or any other alcohol, together with AN as an ignition enhancer. 
       Enhanced fuel=Methanol+water+ AN +urea  Eq. 1
 
       Enhanced fuel=Methanol+water+urea  Eq. 2
 
     Where water, urea and AN; or water and urea form the fuel additives. Urea provides the resistance to corrosion and AN provides ignition improvement/cetane enhancement as described supra. Corrosion resistance is provided by decomposition of urea into ammonia and by-product(s). Ammonia-gas is the main active component for the anti-corrosive action in the exhaust system of vehicles 
     Where, 
       Methanol+3/2O 2 =&gt;CO 2 +2H 2 O 
       Urea+H 2 O=&gt;2NH 3 (gas)+CO 2    
     Typically, the carbon dioxide generated in the two reactions depicted above is corrosive. Carbon dioxide reacts with water as follows: 
       CO 2 +H 2 O=&gt;HCO 3− +H+ 
     As the concentration of CO 2  increases, so does the concentration of the H +  ion. This ion then react with Fe in metals: Fe+2H+=&gt;2H (atom)+Fe 2+  As corrosion proceeds, the ferrous ions produced react with the bicarbonate ions to form ferrous carbonate which precipitated as a scale. 
     However, in this embodiment the ammonia released, mitigates the corrosive effect of carbon dioxide. Although ammonia is corrosive by itself the formed ammonium carbonate and ammonium bicarbonates retard and inhibit corrosion. The possible reactions being 
       CO 2 +NH 3 +H 2 O→(NH 4 )HCO 3  
 
       CO 2 +NH 3 +H 2 O→(NH 4 ) 2 CO 3  
 
     Where the carbon dioxide is captured by the ammonia to form the carbonates and the bicarbonates of ammonia. 
     Pursuant to embodiments of the present disclosure, Ammonium nitrate (AN) has a significant potential as a cetane enhancer for alcohols, such as methanol. The cetane enhancement capability effectively allows AN to be used as an ignition improver for such alcohol fuels. AN is not very soluble in methanol for example, but both methanol and AN are soluble in water. Therefore, there is disclosed a fuel including a mixture of an alcohol, for example ethanol and/or methanol, AN, urea and water (Eq. 1) Also, disclosed is a fuel including a mixture of an alcohol, for example ethanol and/or methanol, urea and water (Eq. 2). Such fuels are beneficially manufactured from a method including:
         (i) Mixing methanol, AN and urea to the desired concentration, for example in a range of 1-10 weight % AN relative to methanol and for example in a range of 1-10 weight % urea relative to methanol, wherein the is methanol included in a concentration having a range of 90-97 weight %, more specifically, 95 weight %; and   (ii) During mixing in (i), adding enough water so that AN and urea (based on Eq. 1); or urea (based on Eq. 2) becomes dissolvable in the methanol water mix.       

     In step (i) of the method, the range in which AN needs to be added is defined by a ratio N/C (namely, Nitrogen to Carbon), wherein Nitrogen atoms come from the AN additive and Carbon atoms, mostly, comes from the fuel, for example methanol. 
     In step (ii) of the method, water needs to be added to an extent that solubilises the required amount of AN and urea, or just urea. The ranges provided are preferentially by volume. 
     The mixture of water, methanol, AN and urea (Eq. 1) and the mixture of water, methanol and urea (Eq. 2) are of advantage in that it can be easily stored over a long-term period without separating out into individual components parts, and does not form an emulsion and does not need to be emulsified. The enhanced fuels pursuant to Eqs.1 and 2 only contain fully soluble compounds and, thus, are considered to be more stable and more reliable in operating conditions. Further, the enhanced fuels pursuant to Eqs. 1 and 2 are considerably cheaper than known diesel fuel substitutes based on methanol, for example employing Avocet, and also is very clean when burnt in an internal combustion engine, for example very low soot production and low NOx production. 
     Methanol can be generated from a variety of sources, for example from fermenting biological waste, form processing wood by-products, from fossil fuel reserves, from coal, from coal liquefaction, from hydrates and so forth; mutatis mutandis ethanol is similarly derivable. 
     Embodiments of the present disclosure are concerned with an introduction of a new additive which increases the efficiency of a given fuel, for example methanol-based fuel, by acting as a cetane enhancer and/or anti-corrosion agent. The additives can be water, urea and AN; or water and urea. The new additive provides at least one of following benefits:
     (a) The new additive allows methanol to act a direct replacement for diesel fuel;   (b) The new additive in solution Is non-explosive, and thus less hazardous in than, for example, octyl nitrate;   (c) The new additive has a potential for application in petrol engines; and   (d) The new additive could reduce corrosion by methanol.   

     “Cetane” is a measure of an ignition quality of a diesel fuel. The higher the cetane measure of a given diesel fuel, the easier it is to start a standard (direct injection) diesel engine using the given diesel fuel. The cetane measure is defined by a percentage, by volume, of cetane, with a chemical name “hexadecane”, in a combustion mixture, containing cetane and 1-methylnaphthalene, whose ignition characteristics match those of a given diesel fuel being tested. Comparisons with other additives and fuels can be made by way of “equivalent cetane measure”, for example as employed when describing embodiments of the present disclosure. 
     Benefits of the enhanced fuels in Eqs. (1 and 2) include:
     (a) The method allows Ammonium Nitrate to be used as an ignition improver to methanol or similar alcohols, in turn allowing the fuel to be used in existing diesel engines with minimum modifications;   (b) The addition of water keeps an engine, burning the fuel, cool (due to a high latent heat of water), thereby decreasing a need for cooling systems, thus making the vehicle more energy efficient;   (c) Lower particulate emission from engines burning the enhanced fuel, namely lower particulate emission than achievable by employing other methods, for example sing exhaust filters, using Adblue spraying in exhaust systems and so forth;   (d) Environmentally friendly, since the N-groups in AN are released as N 2  gas at the end of a burn cycle in a combustion engine;   (e) The enhanced fuel results in a significant reduction in cost in comparison to PEG-dinitrate-based additives, namely AN cost approximately less than 1/20th of PEG-based additives; and   (f) Cooler engine operation consequent upon the introduction of water results in lower NOx formation. Since NOx is the precursor of tropospheric ozone pollution, the reduction in NOx constitutes a significant environmental benefit   (g) The enhanced fuel results in mitigation of corrosion by methanol and constitutes a significant improvement in the fuel quality.   

     In an example, systems and methods are disclosed for the use of an aqueous solution of ammonium nitrate (AN) as an ignition improver and urea as a corrosion inhibitor, directly injected into the engine cylinder. In another example, systems and methods are disclosed for the injection of urea into methanol for corrosion inhibition. 
     Theoretically, systems based on Eqs. (1 and 2) could allow the formation of a small amount of formic acid which is also corrosive. However, formic acid is unlikely to form due to the reaction: 
       Formic acid+1/2O 2 =&gt;CO 2 +H 2 O 
     Where formic acid breaks down into carbon dioxide and water 
     It is noted that as used herein, the term fuel, can be any substance suitable for use as a diesel fuel. According to another aspect, methanol plus lubricity additive can be used directly in spark-ignited petrol engines, so providing a “universal fuel”. 
     Modifications to embodiments of the invention described in the foregoing are possible without departing from the scope of the invention as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “consisting of”, “have”, “is” used to describe and claim the present invention are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. Numerals included within parentheses in the accompanying claims are intended to assist understanding of the claims and should not be construed in any way to limit subject matter claimed by these claims.