METHOD OF REDUCING THE OXIDES OF NITROGEN IN FOSSIL FUELS COMBUSTION AND COMBUSTION PRODUCTS EFFLUENTS

Abstract: Method for reducing the concentration of oxides of nitrogen generated by combustion of fossil fuels or fossil fuel derivatives in various combustion apparatus and combustion devices, including automotive internal combustion engines, gas turbines, combustion heaters, industrial boilers, power plant steam boilers, incinerators, amongst other combustion sources discharging harmful NOx air pollutants into the atmosphere; a method of reducing the oxides of nitrogen generated in the combustion process comprising the step of injecting a mixture of hydrazine and/or hydrazine compounds additive to the fuel in the fuel combustion reaction zone of a combustion apparatus or combustion device, to react with the oxides of nitrogen, contained with the fuel combustion reaction products in the fuel combustion reaction zone, converting the NO and NO2, in reduction reaction with the mixed hydrazine and/or hydrazine compounds, to harmless molecular N2 and H2O which is discharged into the atmosphere in place of the harmful NOx air pollutants.

Description: tlstb'ϊ-l 01 E'i.J..-. Qvl Dl± D-il-ii-. Of N^_ p_ n J , n F r sι_j_ Fuel s Combust on arid Conibustion Frc ucts EffI uents Tec ni l F el d My invention relates to a method of reducing the oxides of nitrogen < NOx > which are generated in the combustion of fossil fuels or fossil fuel derivatives. The oxides of nitrogen discharged with the products of combustion from tht? various combustion sources into ambient atmosphere? have become a major cause of harmful air pol lution, resulting in serious smog problems. The ma j or health irritants in smog are t e oxides of nitrogen < NO 1 - ' amongst which nitrogen dioxide < N0 a > being extremely poisonous gas presents the most serious problem. Major portion of the NOv discharged into the atmosphere comes from fossil fuels combustion in automotive internal combustion engines, but stationary sources of NO discharge such as power plants, fired boilers and process furnaces, incinerators and 51mi l iar combustion equipment are also significant contributors. In these combustion processes NOx is formed as nitric oxide ( NO ; in the high temperature combustion reaction rone from the nitrogen and oxygen in the combustion air and the combustion gases. The high temperatur s in the combustion zone favour NO formation, the original form in which the oxides of nitrogen are created in the combustion process. This NO is subsequently oxidized to N0 4 as soon as the lower temperatures required for this are reached in zones of great local air oxygen surplus and upon discharge into ambient air. In prior art there have been efforts made to find an effective method for removing NO and N0 2 frorn the gaseous combustion effluents of power plant boilers. These efforts have been directed towards methods of selective catalytic reduction of NOx, by using a catalyst in combination with the injection of ammonia vapour into the low temperature region of the combustion effluent gases, wel l downstream and away frorn the combustion reaction zone, at a point lose to the combustion effluent gaε discharge into the atmosphere. The prior art of NOx selective catalytic reduction relates to a method of reducing NOx by mixing ammonia gas with tha combustion effluent gas > where the l w temperature mi ed gases flow stream is directed to contact the catalyst as required for the catalyst to promote an effective catalytic reaction of NOx by ammonia, without exposing the catalyst to thermal degradation, damage or destruction. A more recent prior art effort in the method of NOx reduction from the gaseous combustion effluents of power plant boilers has substituted hydrazine, and another, hydrazine compounds in place of the ammonia being injected into the l w temperature gas stream of combustion effluents near the point of their discharge to the atmosphere. Disci osure £ Invention My invention pertains to a method for reducing the concentration of oxides of nitrogen CNOx) generated in foss l fuels combustion, which would otherwise be dicharged to the atmosphere with the combustion products gas effluents. In one aspect my invention relates, to the fuel additive of Hydrazine I N j H^j 1 and/or Hydrazine-compounds, such as Methylhydrazine CCCH j )N 4 H j 3, Dimethylhydrazine and Unsymmetrical Dimethylhydrazine (i.e. UDMH ), blended into liquid fossil fuels in order to reduce the oxides of nitrogen produced in the combustion reaction of liquid fossil fuels such as gasolines and fuel oils, uεed in internal combustion engines, diesel engines, gas turbines, process furnaces, power plant boilers and other combustion equipment. In another aspect, my invention relates to the addition of Hydrazine and/or Hydrazine- compounds such as Hydrazine-hydrate L " j _ H^ .H^O ] , Methylhydrazine. Dimethylhydrazine and UDMH, to the fossil fuels by injection into the fuel combustion reaction zone for the reduction of the oxides of nitrogen produced in the combustion of solid, liquid and gaseous f ssil fuels in f ssil fuels fired combustion apparatus and devices, including but not limited to gas turbines, power plant boilers f process furnaces, fired heaters, steam boilers, and others. Prior experience with the combustion of rocket propulsion fuels has proved hydrazine and hydrazine compounds to be powerful reducing agents in the combustion reaction process with a variety of oxides of nitrogen used as oxidizer in rocket bipropellant combinations. Hydrazine and several of its compounds employed as rocket fuel propellents are used in combination with a variety of oxides of nitrogen as oxidizers , such as NO , N0 Z , j O^ , HN0 3 , mixed oxides of nitrogen , RFNACI-ΨΛNOJ , ) and WFNA . Several of these bipropellant combinations are hypergolic i.e. the fuel and oxidizer burn spontaneously upon mutual contact ), these are: UDMH with mixed oxides of nitrogen (247.ND), hydrazine with U χ 0. , and hydrazine with RFNA C '.NO^). The hypergolic property of these bipropellent combinations is characteristic o the strong chemical reaction affinity between the fuel and oxidizer to underg the rapid oxidation-reduction process accompanied by the release of larg amount of energy at a correspondingly high reaction rate. The ob j ect of my invention is to utilise these powerful properties of Hydrazine and Hydrazine- compounds for the reduction of the various oxides of nitrogen, in an effective method for reducing the oxides of nitrogen created in the combustion reaction of fossil fuels or f ssil fuel derivatives, by adding Hydrazine and/or Hydrazine-componds to the fuel conibustion reactants in the conibustion reaction zone to interact with the oxides of nitrogen in the combustion reaction process. The added Hydrazine and/or Hyrazine-compounds combined with the fossil fuels undergoing the process of combustion in the combustion reaction zone, react with the combustion generated NOx and remove the NO and N0 a from the products of conibustion by the chemical reduction reaction process, in which the Hydrazine and/or Hydrazine-compounds reduce the oxides of nitrogen to molecular ^ and H^O . Detailed Dessrι_Btj. n of. the Inventio The subject of my invention relates to a method for the reduction of the oxides of nitrogen f NOx ) , including both NO and N0 a , generated in the combustion reaction zone as combustion products of the fuels conibustion reaction process. Said method comprising the step of injecting a mixture of Hydrazine and/or Hydrazine compounds in addition to the fossil fuels within the combustion reaction zone, to act as NOx conibustion reducing agents to reduce the accumulated NO as well as NO j , during the process of fossil fuels combustion in the combustion reaction zone; wherein the NO as well as NOj, is removed from the products of combustion in the reduction reaction with the added mi tureof Hydrazine and/or Hydrazine compounds, by converting the NOx to harmless mol cular ^. and Hj.0 in the combustion product effluent gasses discharged frorn the combustion process. In practice of this invention, in order to obtain effective reduction of NO', including NO in the fossil fuels conibustion products, it is essential that the admixture of Hydrazine and/or Hydrazine-compounds being used in the combustion process with fossil fuels, be thoroughly intermixed and dispersed into the combustion reactants and products of combustion within the combustion reaction zone, to facilitate contact between the oxides of nitrogen and the Hydrazine and/or Hydrazine-compounds injected into the combustion reaction zone. Combustion reaction zone in this invention is ent to be that physical volume of fossil fuels combustion reaction space occupied by the combustion flame and the adjacent flame surrounding space involved in the fuel combustion process. The amount and rate at which Hydrazine and/or Hydrazine-compounds are needed in the fossil fuels combustion reaction zone for the reduction of NO, which is being produced in the fossil fuels combustion process, is primarily dependent on the rate and amount of NO being generated , which in turn depends on the fuel consumption rate and type of fossil fuel used in the combustion process, and the type and physical design of the fossil fuels fired combustion apparatus or device. Basically, in the reduction reaction of 2 moles NO reacting with one mole of Hydrazine H^N.N H j _ , forming 2 moles N ft and 2 moles H^O in the process, or one mole NO reacting with one mole UDMH producing one mole each Nj. and H j .0. Consequently in a theoretically ideal reduction reaction the amount of Hydrazine and/or Hydrazine-compounds injected in a perfect mixture with the fossil fuels and combustion air in the combustion reaction zone would range from 0.5 to 1.0 moles per mole of NO generated in the fuel combustion process. However, the perfect mixture conditions in which the total amount NO contained in the mixture comes into contact with the total amount of Hydrazine and/or Hydrazine-compounds in the same mixture in the combustion reaction zone, can not be realistically achieved in the case that only the theoretically ideal amount of Hyrazine and/or Hydrazine compounds were injected into the fuel combustion reaction zone, allowing a fraction of the NO to escape the reduction reaction . Therefore, in order to assure that al 1 of the NO formed in the fuel combustion process at any given instant of time is completely reduced to N j . and H t 0 an excess amount Hydrazine and/or Hydrazine-compounds, over and above of the theoretically ideal amount, will be injected into the fuel combustion reaction zone until reduction of all NO is accomplished. It may be expected that the injection of about 100%, or more excess of Hydrazine and/or Hydrazine-compounds into the fuel combustion reaction zone, per each mole of NO formed in the fuel combustion process, will be sufficient for the reduction of al I of the NO generatated by most types of fossil fuel fired combustion apparatus and devices. The Hydrazine and/or Hydrazine-co pound reduction reaction of NOv contained in the fossil fuels combustion reaction zone, is carried out at the operating conibustion pressures of the respesctive types of conibustion devices, and at combustion presuures ranging from about 0.5 atmospheres to 100 atmospheres . For example in a typical gas turbine combustion process the conibustion of 1 kg of diesel fuel produces about 20 g NO j , discharged in the gas turbine combustion effluents wich is approximately 0.435 moles of N0 λ per kg of diesel fuel combustion, representing about 0.29 moles of NO formed in the combustion of 1 Ig of diesel fuel in the gas turbine. Using the average ratio of 2.0 moles of Hydrazine for the reduction of 1 mole of NO, the amount of Hydrazine to be injected into the gas turbine combustion reaction zone, for the reduction of the NO generated in the conibustion of each 1 Ig of diesel fuel oil is about 0.58 mol s or 18.53 g of hydrazine per 1 Ig of diesel oil consumed in gas turbine fuel conibustion, converting the NO contained within the combustion products in the combustion reaction zone to molecular t » and H % 0. In an embodiment of my invention for a gas turbine operating on the combustion of fuel oil or natural gas, the amount of Hydrazine needed for the reduction of the amount of NO produced in the gaε turbine conibustion reaction zonefs ) , is injected in water solution as Hydrazine-hydrate < N H .H 0 admixture in combination with the gas turbine combustion fuel into said combustion r ac ion z nefs.). In another embodiment of my invention for gas turbines, internal conibustion engines, automotive internal conibustion engines, power plant boilers as wel l aε other fossil fuel fired conibustion devices operating on combustion of liquid fossil or fossil derivative fuels, the amount of Hydrazine needed for the reduction of the NOx formed in the fuels conibustion process, is injected into the combustion reaction zone's) within the liquid fossil fuel containing the blended fuel additive admixture of Hyrazine and/or fuel compatible Hydrazine-compounds such as. Methyl hydrazine. Dimethylhydrazine or UDMH. In yet another embodiment of my invention for fossil fuels fired combustion apparatus operating on the combustion of solid fuels, gaseous fuels as wel l as liquid fuels, the amount of Hydrazine, needed for the reduction of the amount of NOx formed in the fuel combustion process of said fuels, is injected into the combustion reaction zones in water or steam solution t N^H^ ' H^O > where the water or steam propel Is and mixes the Hydrazine with the fuel and combustion air in the ongoing combustion process in the combustion reaction zon Cs). While the above description contains many specificities, the reader should not construe these as limitations on the scope of the invention, but merely as exemplifications of prefered embodiments thereof. For example skilled artisans will readily be able to change the proportions of the amounts of Hydrazine and/or Hydrazine-compounds injected into the fossil fuels combustion reaction zone, above and beyond the amount needed for the reduction of the total amount of NO being formed in the fuel combustion process, and which iε strongly influenced and dependent on a given fossil fueled combustion apparatus type and design, as wel I as the type of fuel used. They can make manv variations in the method of intjecting Hydrazine and/or Hydrazine-compounds into the comobustion reaction zone. In fact they can redesign and make physical changes in combustion devices wherein the Hydrazine and/or Hydrazine-compounds could be injected into the fuel combustion reaction zone by admixture within the combustion air. Accordingly the reader is requested to determine the scope of my invention by the appended claims and their legal equivalents and not by the examples which have been given.

Claims: Cj_ai_mε 1. A process for reducing the oxides of nitrogen, generated in the combus ion of fossil fuels or fossil fuel derivatives within fuel combustion reaction zones of fossil fuels fired combustion apparatus or combustion devices, the said process for reducing oxides of nitrogen comprising: the εtep of injecting an admixture of oxides of nitrogen reducing agents comprising either hydrazine or hydrazine compounds, or combination of both, a means of injecting said oxides of nitrogen reducing agents into the combustion reaction zone containing a mixture of combustion fuels, combustion air, and products of fuel combustion including the oxides of nitrogen generated within said combustion reaction zone in combustion of said fossil fuels or fossil fuels derivatives, whereby the said admixture of oxides of nitrogen reducing agents interact with εaid oxides of nitogen within said c mbusti n reaction zone, converting said oxides of nitrogen in a chemical reduction process to harmless molecular N t and H^D, which is subsequently discharged to the ambient atmosphere in the combustion products effluent gases. 2. A process according to claim 1 wherein a fossil fuels fired combustion apparatus or combustion device using a means of injecting liquid fuels with the oxides of nitrogen reducing agents of either hydrazine, or hydrazine compounds, or both in combination, intermixed with said liquid fossil fuels or liquid fossil fuel derivatives into the combustion reaction zone, whereby said oxides of nitrogen reducing agents interact in the fuel combustion process with the oxides of nitrogen being generated within said combustion reaction zone, reducing said oxides of nitrogen to molecular N^ and H j ,_0 in the combustion products effluent. 3. A process according to claim 1 wherein a combustion apparatus or combustion device uses a gaseous fu l, liquid fuel or solid fuel in firing said combustion apparatus or combustion device, and the oxides of nitrogen reducing agent comprising hydrazine-hydrate C N j - .H j O ) is injected separately from the combustion fuels by independent means into the fossil fuels combustion reaction zone . 4. A process according to claim 2 wherein the oxides of nitrogen reducing agents admixture blended into the liquid fossil fuels or liquid fossil fuels derivatives consists essentially of dimethylhydrazine and unsymetrical dimethyl ydrazine, or methylhydrazine, or a combination of both. 5» A process according to claim 3 wherein the oxides of nitrogen reducing agent consisting essentially of hydrazine-hydrate in the form of hydrazine solution in steam is injected into the fuel combustion reaction zone to mix with the combustion air and combustion fuel to reduce the oxides of nitrogen included in the fuel combustion products contained within said fuel combustion reaction zone.

Inventors: TURCHAN OTTO CHARLES, TURCHAN, OTTO, CHARLES
Applicants: TURCHAN OTTO CHARLES, TURCHAN, OTTO, CHARLES
Application year: 1988
Main classification: B01J8
IPC codes: B01D53