Title of Invention

METHOD OF REMOVAL OF CARBONYL COMPOUNDS ALONG WITH ACID GASES FROM CRACKED GASES IN ETHYLENE PROCESS

Abstract

METHOD OF REMOVAL OF CARBONYL COMPOUNDS ALONG WITH ACID GASES FROM CRACKED GASES IN ETHYLENE PROCESS The invention relates to method of removal of carbonyl compounds, not only like acetaldehyde and others, but also polymeric deposits formed on internal surfaces of caustic scrubber in ethylene process. Earlier patents disclose compounds for inhibiting polymerization. As efficiency of inhibition is never 100 %, unterminated carbonyl compounds polymerize, separate out from system and form deposits on internal surfaces of scrubber, ultimately plugging and fouling equipment. This leads to huge production / commercial / financial losses, as the plant is to be shut down for cleaning for long time - interval. The invention comprises introducing premixed additives into feed stream of caustic wash unit, wherein effective amount of additive comprises of sodium diothionite salts and sodium metabisulfite and / or combination thereof, with aliphatic / aromatic amino acid, or lactam, and agitate and heat the mixture, thereby inhibiting polymerization and also dissolving polymeric deposits being formed or already formed. The method is useful for continuous running of caustic / amine scrubber, without any need of shutting down the unit for cleaning.

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (See section 10; rule 13) 1. METHOD OF REMOVAL OF CARBONYL COMPOUNDS ALONG WITH ACD3 GASES FROM CRACKED GASES IN ETHYLENE PROCESS. 2. Dorf Ketal Chemicals India Pvt. Ltd Dorf Ketal Towers, D'monte Street, Orlem, Malad (W), Mumbai 400 064, Maharashtra State, India. Indian company registered under Indian Companies Act, 1956 The following specification particularly describes the nature of this invention and the manner in which it is to be performed:- METHOD OF REMOVAL OF CARBONYL COMPOUNDS ALONG WITH ACID GASES FROM CRACKED GAS IN ETHYLENE PROCESS TECHNICAL FIELD OF THE INVENTION The present invention generally relates to a method of removing undesired byproducts from pyrolytic cracking of hydrocarbons. The invention more particularly relates to a method for removal of carbonyl compounds not only like acetaldehyde and other carbonyl compounds but also its polymer along with the other acidic gases like H2S and CO2 that are formed when cracked gasses enter a caustic or an amine unit within an ethylene plant where the cracked gases are produced in a pyrolysis heater during the pyrolytic cracking of hydrocarbon such as naphtha, gas oil or ethane, propane, butane and such other hydrocarbons. BACKGROUND OF THE INVENTION In pyrolytic cracking operations, feed stocks such as ethane, propane, naphtha, kerosene, gas oil, fuel oil and the like undergo "cracking," that is the removal of hydrogen, to form unsaturated hydrocarbons. Pyrolytic cracking also tends to produce oxygenated hydrocarbons, including carbonyl compounds such as acetaldehyde. In a typical operation, the cracked effluent stream is quenched, fractionated and compressed. Acidic contaminants such as hydrogen sulfide, carbon dioxide and mercaptans are then typically removed from the effluent. During the scrubbing operation of these gases with caustic or amine some oxygenated compounds are removed. At the same time, however, the basic conditions in the scrubber tend to cause base-induced condensation reactions (due to aldol condensation mechanism) of the carbonyl compounds, including aldehydes (for example, acetaldehyde) and/or ketones, which in turn result in the formation of polymers. These polymers deposit on the internal surfaces of the scrubber. As the mass of polymer grows, it leads to fouling and can eventually obstruct the flow of liquids through the system. This is undesirable, as the operating system must be shut down for a significant amount of time in order to remove the deposited polymer and clean the equipment. This operation itself is very expensive involving many man hours and financial loss. The prior art systems treat caustic towers with an injection of a compound to inhibit the aldol condensation mechanism. In order to inhibit aldol condensation the prior art systems mostly use additives that are organic in nature and contribute to chemical oxygen demand for caustic used in the scrubbing process. In addition, the prior art additives typically require additive to reactant(that is carbonyl compound) molar ratios to be of at least about 1:1 for effective performance. Further the adducts of the high molecular weight polymers with these compounds tend to be insoluble in the basic system. Thus, the prior art additives are ineffective for the purpose of maintaining unobstructed flow through the system and reducing significant maintenance time for removing the polymer deposits and cleaning the equipment.. A current practice in the industry is to treat the weak caustic in the caustic tower with gasoline or another aromatic fraction in order to remove the polymers before sending it to the spent caustic oxidation unit, in order to prevent fouling there. The resulting gasoline-containing stream causes disposal and operational problem, however. Likewise, routing the gasoline-containing stream to other operating units can cause problems due to the presence of the caustic, as it may affect pH, catalyst and other plant parameters. Another current practice in the industry is to treat the caustic tower with organic additives and despite the various advances in the art it remains desirable to provide an alternative method to improve the performance of this particular unit in the industry. There have also been shortcomings discussed later when any of these additives have been used concurrently to provide a synergistic effect in such systems. In the past, prevention of polymerization of oxygenated compounds, such as carbonyl containing organics in basic solutions, has been attempted by process of inhibition only by adding amine compounds such as hydroxylamine hydrochloride, hydroxylamine sulfate, hydrazine, carbohydrazides and the like. Several patents which relate to methods of inhibiting carbonyl fouling due to polymerization are listed below. It is found that these patents discuss only the removal of carbonyl compounds but fail to address the issue of polymers which are formed as a result of polymerization of unscavenged portion of the carbonyl compounds during the use of inhibiting additive and also of polymers already existing in the system. Thus these patents discuss only the method of inhibition of polymerization. U.S. Pat. No. 4,673,489, discloses using hydroxylamine and its salts of hydrochloric acid and sulfuric acid to inhibit polymer formation caused by condensation reactions of aldehydes contained in caustic scrubber units. One disadvantage of the method is that the additive has to be used in almost molar proportion. The other disadvantage is that these chemicals are expensive and must be over fed to the caustic wash unit system. Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. U.S. Pat. No. 4,952,301, discloses using ethylenediamines with the molecular formula NH sub 2 ( CH sub 2 CH sub 2 NH ) sub x H were x is an integer ranging from about 1 to about 10 to inhibit carbonyl based fouling, particularly aldehyde fouling, that often occurs during caustic scrubbing of liquid or gas phase hydrocarbon streams in the base wash unit. Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. U.S. Pat. No. 5,264,114 granted to Dunbar also discloses the use of amine compounds to inhibit the deposition of foulants during caustic washing of the hydrocarbon gases contaminated with the carbonyl compounds which comprises of treating the said hydrocarbon gases with an aqueous amine solution wherein the said aqueous amine solution comprises water and an amine compound having a concentration range of 2 ppm to about 5000 ppm and wherein the said amine compound is selected from group of organic compound of the formula R NH SUB 2 and R sub 2 NH wherein the R is selected from the group of alkyl or aryl groups. Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. Carbohydrazide has been disclosed as useful for inhibiting polymeric fouling deposits during the caustic scrubbing of pyrolytically-produced hydrocarbons contaminated with oxygen-containing compounds in U.S. Pat. No. 5,160,425. Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. US Pat No. 5288394 to Lewis et al describes and claims a method of inhibiting formation of polymeric fouling deposits after the caustic scrubbing of hydrocarbon stream contaminated with oxygenated compounds with a basic washing solution having pH more than 7 comprising adding to the said hydrocarbon stream a sufficient amount of inhibiting formation and deposition of fouling materials of a composition comprising at least one hydrazide compound Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. U.S. Pat. No. 5,194,143, granted to Roling describes and claims a method for inhibiting the formation of polymeric based fouling deposits during the basic washings of olefins containing hydrocarbon contaminated with oxygenated compounds comprising adding to the wash about 1 to 10000 parts per million acetoacetate ester compound having the formula CH sub 3 COCH sub 2 c sub x H sub w here x is an integer from about 1 to about 8 and y is an integer from about 3 to about 17. Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. U.S. Pat. No. 5,220,104 discloses the use of percarbonate salts for the inhibition purpose. Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. U.S Pat No 5770041 Lewis et al. describes the use of certain aldehydic compounds without alpha hydrogen atom or non enolizable aldehydes like formaldehyde, glyoxal and the like as aldol inhibitor, but again in this case the said inhibitors are to be used at least thrice the molar ratio for per mole of carbonyl species. Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. U.S. Pat No 5710455 discloses the use of certain organic amine inhibitor like sulfanilic acid for inhibiting the aldol condensation. Also this patent does not discuss the problems related to and provide solution to remove carbonyl compounds and polymers thereof which are unscavenged during the inhibition process and more importantly already existent polymers. All the patents of the prior art discussed above show that they always discuss treatment of the caustic with injection of a compound only to inhibit polymer formation by aldol condensation mechanism. Apart from the above mentioned disadvantages there are serious technical problems which exist about which the prior art people are totally unaware about. Hence there was no question of earlier researcher trying to tackle and resolve these problems. These technical problems are described below. One serious technical problem is that, as is known to those skilled in the art is that the polymer formation of carbonyl compounds is extremely rapid and takes place within few minutes and the scavenging of the carbonyl compounds is not 100 % by inhibition process. Thus one important and obvious requirement for the process of inhibition is that the inhibitor be present in the caustic tower before the carbonyl compounds enters the tower. In a situation where any delay in supply of the inhibitor or non availability of the inhibitor or incomplete availability of the inhibitor, in the caustic tower will cause these carbonyl compounds to polymerize within few minutes which is very detrimental to the unit leading to fouling. This is a typical problem commonly associated with the method of inhibition. The unscavenged portion of carbonyl compounds polymerizes and deposits on the trays which lead to fouling and plugging of the equipments and eventually to the equipment failure. Another very important technical problem which exist is that the inhibitor used by the earlier research workers can react with only non polymerized carbonyl compounds and very low molecular weight caustic soluble species but not high molecular weight polymers. It is known to those skilled in the prior art that the non polymerized and low molecular weight species compounds are soluble in the caustic system which therefore do not cause any problem due to deposition whereas the high molecular weight polymers are insoluble in the caustic system, thereby depositing and fouling the equipment. The low molecular weight caustic species can be defined as 2 or 3 repeating units of acetaldehyde and like. For purposes of this invention, low molecular weight species may be defined as 2 or 3 repeating units of acetaldehydewhere as high molecular weight polymer may be defined as polymer having greater than 3 repeating units of acetaldehyde. Hence there is a need to develop a method which will not only inhibit the formation of polymers but in addition also uses mechanism of dissolution to dissolve the polymers formed in the caustic scrubber in spite of inhibiting action and also polymers already existing in the unit and its down stream units. OBJECTS AND ADVANTAGES OF PRESENT INVENTION Accordingly different objects and advantages of the present invention are described below: One object of the present invention is to inhibit the formation of polymers of carbonyl compounds in a caustic scrubber thereby inhibiting fouling due to oxygenated hydrocarbons. Another important object of the invention is to dissolve the polymers in caustic scrubber which are formed in spite of inhibition action and also polymers which are existing in the scrubber. Yet another object of the invention is to reduce the concentration of oxygenated hydrocarbons particularly carbonyl compounds in equipments and products thereof. Further object is to scavenge oxygenated hydrocarbons without posing polymerization problems and without interfering with plant operations or operations of the individual process operations. Still further object of the invention is to provide a inventive product which can be premixed with the caustic used for making the scrubbing solution. Yet further object is to develop a inventive combination of chemicals so as to react with non- polymerized carbonyl compound and also low molecular weight species and high molecular weight carbonyl polymers such that the reacted adduct is soluble in the caustic solution thereby preventing plugging and fouling of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS Fig 1A and lb describe chemical compounds useful in the present invention. SUMMARY OF THE INVENTION During the scrubbing operation in the caustic or amine towers in the chemical industry condensation reaction of carbonyl compounds lead to formation of polymers which further leads to fouling and obstructing the flow of liquid through the system. The present invention provides a method to mitigate fouling due to polymerization of carbonyl compounds. This is achieved by using certain inorganic salts like sodium dithionite, sodium metabisulfite, certain amino acids like amino caproic acid, sulfanilic acid and combinations there of, as additives for caustic tower. All the compounds achieve the effect of inhibition of polymer formation. Some of the compounds carry out the scavenging of carbonyl compounds by inhibition of polymer formation and also by dissolution of polymers formed as the result of the reaction and also the polymers already existing in the caustic tower before the reaction. Also the present invention can be used along with the caustic in the caustic tower, that is, the compounds of the invention can be premixed with the caustic used for making the scrubbing solution. DETAILED DESCRIPTION OF THE INVENTION The present invention includes a method of inhibiting the polymer formation and also for dissolving polymers formed during reaction as well as existing polymer, that is taking care of carbonyl compounds, low molecular weight species and high molecular weight polymer which lead to deposit formation in caustic or alkaline scrubbers that are used for scrubbing acidic gases such as carbon dioxide and hydrogen sulfide from the effluent streams formed during the pyrolytic cracking of hydrocarbons like naphtha, ethane, and propane. The cracking operations also produce oxygenated compounds such as vinyl acetate or acetaldehyde, which undergo polymerization under the alkaline conditions in the scrubber. Upon hydrolysis under alkaline conditions vinyl acetate releases acetaldehyde., which contributes further to the buildup of polymeric deposits. Inorganic salt like sodium dithionite The most preferred embodiment of the present invention includes a method wherein certain inorganic salt like sodium dithionite, is introduced into the feed stream to caustic wash unit system to mitigate fouling. This mitigation of fouling happens by inhibition of polymer formation and by dissolving the polymer if formed during the reaction and also the existent polymers. Sodium dithionite does the work of inhibition of polymer formation. Also if any polymer is formed by escaping the inhibition action or if any polymer already exits in the system before the addition of the additive, sodium dithionite dissolves the same thereby mitigating any fouling. Thus addition of sodium dithionite causes mitigation of fouling by doing a dual function that is of inhibition of polymer formation and of dissolving polymers formed during reaction and also polymers already existing in the caustic scrubber. In this most preferred embodiment of the present invention the inorganic salt like sodium dithionite should be added to the alkaline scrubber in an amount wherein a molar ratio of carbonyl compound to inorganic salt is from about 1:0.01 to about l:25mole, preferably from about 1:0.05 toaboutl:0.005 mole and more preferably from about 1:1 to aboutl:0.01mole. The preferred amount of additive ranges from about 0.5 to about 1,000,000 parts of additive per one million part of the aqueous scrubbing medium used in the caustic wash unit system, more preferably additive ranges from about 25 to about 200 ppm. The sodium dithinoite as a additive can be added as neat product or in any form available commercially or as a solution in water or alkali. Referring to experiment 1 and 2 of Table 1 of example 2 showing the inhibition action that is before polymerization it is clearly seen that at the mole ratio of 0.15 of sodium dithionite the value of %T is 68.5 as compared to the value of 0.5% of the blank that is without any inhibitor. Thus this proves the excellent efficiency of sodium dithionite in effecting inhibition of polymer formation. Referring to experiment 1 and 2 of Table 2 of example 3 the surprising and dramatic effect of dissolution of polymer is seen. The value of %T is 0.5 for the blank and for sodium dithionite is 62.5. The blank run in the example can be interpreted as example of presence of the unscavenged carbonyl, low molecular weight species, high molecular weight polymers and already existing polymer. Thus this example clearly demonstrates the effect of the dissolution of the polymers. Those skilled in the art are aware of the fact that even a slight delay in the addition of the additive leads to formation high molecular weight polymers which eventually leads to deposition of the polymers. As such the excellent effect of addition of sodium dithionite is demonstrated. Combination of Inorganic salt like sodium dithionite and organic aliphatic amino acid and derivatives Another embodiment of the present invention includes a method wherein said inorganic salt sodium dithionite is blended in synergistic combination with aliphatic amino acid including but not limited to 6 amino caproic acid to mitigate the effects of polymerization in the caustic wash unit system. The blends of inorganic salt like sodium dithionite and aliphatic amino acids particularly 6 amino caproic acid not only inhibit polymer formation but also dissolve the polymers formed during the reaction as a result of polymerization of carbonyl compounds by the aldol condensation as described above and also the existent polymers. Thus each of the blends of sodium dithionite and aliphatic amino acids carries out mitigation of fouling by doing a dual function, that is, of inhibition of polymer formation and of dissolving polymers formed during reaction and also polymers already existing in the caustic scrubber. In this embodiment of the present invention the blend of inorganic salt like sodium dithionite and the aliphatic amino acid like 6 amino caproic acid should be added to the alkaline scrubber in an amount wherein a molar ratio of carbonyl compound to said blend is from about 1:0.01 to about l:25mole, preferably from about 1:0.05 to about 1:0.005 mole and more preferably from about 1:1 to about 1:0.01 mole. The amount of additive ranges from about 0.5 to about 1,000,000 parts of inhibitor per one million part of the aqueous scrubbing medium used in the caustic wash system, more preferably amount of additive ranges from about 25 to about 200 ppm. The combination of inorganic salt and the aliphatic amino acids can be added either as blend or as individual components in neat or solution form .The amino acid can be added either as neat product or as an aqueous solution containing from about 0.05 to about greater than about 60 weight percent, preferably from about 18 to about 38 weight percent. Amino acids that are particularly suited for use in the accordance with this embodiment of the invention include but are not limited to 6 amino acid such as the amino hexanoic acid made from epsilon caprolactam, glycine, or taurine, or any compound having one of the structures described in figure la and lb. Also suitable are the derivatives, isomers, and inorganic or organic salts of these compounds. The amino acids mentioned above can be used in its salt form or as pure amino acid or impure form or combinations thereof. Referring to experiment No 1, 2 ,3 of Table 3 of example 2 it is seen that synergy is demonstrated by use of combination of compounds as shown herein for polymer inhibition. With sodium dithionite with a molar ratio of 0.1 the value of %T is 18.5 with amino caproic acid in the molar ratio of 0.026 is 0.3 but with the combination of sodium dithionoite and amino caproic acid at 0.126 mole is 82%. It is seen further in experiment No 4 of Table 3 that the amino caporic acid synthesized from caprolactam shows similar behaviour. Thus this proves the excellent efficiency of combination of sodium dithionite and amino caproic acid in effecting inhibition of polymer formation. Referring to experiment no. 1,2,3 and 4 of Table 2 of example 3 it can be clearly seen that the combination of sodium dithionite and amino caproic acid demonstrate a synergy in dissolving the polymer. The value of %T of individual components are sodium dithionite at a molar ratio of 0.5 is 62.5 and for amino caproic acid at mole ratio of 0.087 is 0.5 but the blend at the total mole ratio of 0.5879 has a value of 77.05%. The blank run in the example can be interpreted as example of presence of the unscavenged carbonyl compound, low molecular weight species, high molecular weight polymers and already existing polymer. Thus this example clearly demonstrates the effect of the dissolution of the polymers. Thus this example clearly demonstrates the effect of the dissolution of the polymers. Those skilled in the art are aware of the fact that even a slight delay in the addition of the additive leads to formation high molecular weight polymers which eventually leads to deposition of the polymers. As such the excellent effect of addition of combination of sodium dithionite and amino caproic acid is demonstrated. Combination of Inorganic salt like sodium dithionite and lactam and derivatives Further embodiment of the present invention includes a method, wherein blends of inorganic salt like sodium dithionite and certain lactams including but not limited to epsilon caprolactam are used to mitigate the effects of polymerization in the caustic wash unit system. Thus each one of the blends of inorganic salt like sodium dithionite and lactum particularly epsilon caprolactam not only inhibit polymer formation but also dissolve the polymers formed during the reaction as a result of polymerization of carbonyl compounds by the aldol condensation as described above and also the existent polymers. Thus each one of the blends of sodium dithionite and lactam carries out mitigation of fouling by doing a dual function, that is, of inhibition of polymer formation and of dissolving polymers formed during reaction and also polymers already existing in the caustic scrubber. In this embodiment of the present invention the blend of inorganic salt like sodium dithionite and the lactam like epsilon caprolactam should be added to the alkaline scrubber in an amount wherein a molar ratio of carbonyl compound to said blend is from about 1:0.01 to about l:25mole, preferably from about 1:0.05 to about 1:0.005 mole and more preferably from about 1:1 to about 1:0.01 mole. The amount of additive ranges from about 0.5 to about 1,000,000 parts of inhibitor per one million part of the aqueous scrubbing medium used in the caustic wash system, more preferably amount of additive ranges from about 25 to about 200 ppm. The combination of inorganic salt and the lactam or sultam can be added either as blend or as individual components in neat or solution form .The lactam can be added either as neat product or as an aqueous solution containing from about 0.05 to about greater than about 60 weight percent, preferably from about 18 to about 38 weight percent. Lactams that are particularly suited for use in the accordance with this embodiment of the invention include but are not limited to lactams such as epsilon caprolactam but any compound having one of the structures described in figure 1 a and lb. Also suitable are the derivatives, isomers, and inorganic or organic salts of these compounds. When amino acids or lactams are used along with the inorganic salts, particularly sodium dithionite they react with unscavenged carbonyl compounds, low molecular weight species, high molecular weight polymers and already existing polymer. Thus this example clearly demonstrates the effect of the dissolution of the polymers and the reacted adduct is soluble in the caustic solution. Thus, the amino acid and the inorganic salts in synergistic ratio solubilize the polymers formed and prevent precipitation and fouling of the equipment. The present additives have the dual advantage of working as polymerization inhibitor by reacting with acetaldehydes as well as solublizing any polymers formed during reaction as well as existing polymers by reacting with them. Referring to experiment no. 1,7,8 of Table 3 before polymerization of example 2 a highly synergistic effect is seen between sodium dithionite and caprolactam. The individual components in experiment 1, the sodium dithionite in the molar ratio of 0.1 mole has %T value of 18.5 and caprolactam in the molar ratio of 0.3 moles has a %T value of 0.4 but the experiment no. 8 the combination of caprolactam and sodium dithionite has value of 82.9 in the molar ratio of 0.250 only. Thus this proves the extraordinarily excellent efficiency of combination of sodium dithionite and caprolactam in effecting inhibition of polymer formation. Referring to experiment no 2, 6 and 7 of Table 2 example 3 ( after polymerization) a synergistic effect of dissolution of polymer is seen. The individual component sodium dithionite has a value of 62.5 %T at O.Smole and caprolactam has a value of 11.4 at 0.3 mole where as the combination of both has a value of 69.7%. The blank run in the example can be interpreted as example of presence of the unscavenged carbonyl compound, low molecular weight species, high molecular weight polymers and already existing polymer. Thus this example clearly demonstrates the effect of the dissolution of the polymers. Those skilled in the art are aware of the fact that even a slight delay in the addition of the additive leads to formation high molecular weight polymers which eventually leads to deposition of the polymers. As such the excellent effect of addition of combination of sodium dithionite and caprolactam is demonstrated. Combination of Inorganic salt like sodium dithionite and aromatic amino acid and derivatives Yet another embodiment of the present invention includes a method wherein said inorganic salt sodium dithionite is blended in synergistic combination with aromatic amino acids including but not limited to sulfanilic acid to mitigate the effects of polymerization in the caustic wash unit system. The blends of inorganic salt like sodium dithionite and aromatic amino acids particularly sulfanilic acid inhibit polymer formation during the reaction as a result of polymerization of carbonyl compounds by the aldol condensation as described above. The combination of inorganic salt like sodium dithionite and organic aromatic amino acids including sulfanilic acid exhibits a tremendous synergy for inhibition of polymer formation. In this embodiment of the present invention the blend of inorganic salt like sodium dithionite and the aromatic amino acid like sulfanilic should be added to the alkaline scrubber in an amount wherein a molar ratio of carbonyl compound to said blend is from about 1:0.01 to about l:25mole, preferably from about 1:0.05 to about 1.0.005 mole and more preferably from about 1:1 to about 1:0.01 mole. The amount of additive ranges from about 0.5 to about 1,000,000 parts of inhibitor per one million part of the aqueous scrubbing medium used in the caustic wash system, more preferably amount of additive ranges from about 25 to about 200 ppm. The combination of inorganic salt and the aromatic amino acids can be added either as blend or as individual components in neat or solution form. The aromatic amino acid can be added either as neat product or as an aqueous solution containing from about 0.05 to about greater than about 60 weight percent, preferably from about 18 to about 38" weight percent. Aromatic Amino acids that are particularly suited for use in the accordance with this embodiment of the invention include but are not limited to aromatic amino acid such as sulfanilic acid , or any compound having one of the structures described in figure 1 a and lb. Also suitable are the derivatives, isomers, and inorganic or organic salts of these compounds. The aromatic amino acids mentioned above can be used in its salt form or as pure aromatic amino acid or impure form or combinations thereof. Referring to experiment 1,5,6 of table 3 of example 2 a synergistic effect of polymer inhibition is seen between sulfanilic acid and sodium dithinoite. The %T value of the individual components that is i.e. sodium dithionite in molar of 0.1 is 18 , for sulfanilic acid in the mole ratio of 0.16 is 0.2 where as the blend at the sum total mole ratio of 0.260 is 86.7%. Thus this proves the excellent efficiency, of combination of sodium dithionite and sulfanilic acid in effecting inhibition of polymer formation. Combination of Inorganic salt like sodium dithionite and Sodium metabisulfite Yet another embodiment of the present invention includes a method wherein said inorganic'salt sodium dithionite is blended in synergistic combination with another inorganic salt like sodium metabisulfite not limited to sodium metabisulfite to mitigate the effects of polymerization in the caustic wash unit system. The blends of inorganic salt like sodium dithionite and sodium metabisulfite inhibit polymer formation during the reaction as a result of polymerization of carbonyl compounds by the aldol condensation as described above. The combination of inorganic salt like sodium dithionite and sodium metabisulfite exhibits a synergy for inhibition of polymer formation. In this embodiment of the present invention the blend of inorganic salt like sodium dithionite and sodium metabisulfite should be added to the alkaline scrubber in an amount wherein a molar ratio of carbonyl compound to said blend is from about 1:0.01 to about l:25mole, preferably from about 1:0.05 to about 1:0.005 mole and more preferably from about 1:1 to about 1:0.01 mole. The amount of additive ranges from about 0.5 to about 1,000,000 parts of inhibitor per one million part of the aqueous scrubbing medium used in the caustic wash system, more preferably amount of additive ranges from about 25 to about 200 ppm. The inorganic salts can be added as blend or as individual components which further can be added either as neat product or as an aqueous solution or as an alkaline solution. Referring to experiment 1,9,12 of table 3 of example 2 . a synergistic effect of polymer inhibition is seen between sodium metabisulfite and sodium dithionite. The %T value of the individual components that is sodium dithionite in molar of 0.1 is 18 , for sodium metabisulfite in the mole ratio of 0.0.09 the %T value is 35 where as the blend at the sum total mole ratio of 0.19 has a %T value of 93%. Thus this proves the excellent efficiency of combination of sodium dithionite and sodium metabisulfite in effecting inhibition of polymer formation. Inorganic Salt like sodium metabisulfite Still another embodiment of the present invention includes a method wherein certain inorganic salt like sodium metabisulfite, is introduced into the feed stream to caustic wash unit system to mitigate fouling. This mitigation of fouling happens by inhibition of polymer formation. In this embodiment of the present invention the inorganic salt like sodium metabisulfite should be added to the alkaline scrubber in an amount wherein a molar ratio of carbonyl compound to inorganic salt is from about 1:0.01 to about l:25mole, preferably from about 1:0.05 8 toaboutl :0.005 mole and more preferably from about 1:1 to aboutl:0.01mole. The preferred amount of additive ranges from about 0.5 to about 1,000,000 parts of additive per one million part of the aqueous scrubbing medium used in the caustic wash unit system, more preferably additive ranges from about 25ppm to about 200 ppm. The sodium metabisulfite as a additive can be added as neat product or in any form available commercially or as a solution in water or alkali. Also referring to the experiment no 7, 10 ,14 of the Table 1 of example 2 same table it is seen that sodium bisulfite in the molar ratio of 0.125 has %T value of 2.8, sodium sulfite has a %T value of 0.35 and where as sodium metabisulfite ( present invention) has a %T value of 80.7%. Thus this demonstrates the excellent efficiency of sodium metabisulfite in effecting inhibition of polymer formation. Premixed Additive for caustic wash unit system to function as carbonyl scavenging tower also Yet further embodiment of the present invention includes a method of converting the usual caustic wash unit system which is commonly known as caustic tower, into a carbonyl scavenging tower. This conversion can be achieved by premixing the additives as individual compound or combination of compounds discussed in the embodiments of the present invention described above, with the caustic solution, before the caustic solution is admitted into the caustic tower. In the current practice the additives are externally added to the tower by a separate supply unit supplying the additive. One disadvantage of this practice is that the tower may run only with caustic solution without additive in case of failure of the supply unit of the additive. Those skilled in the art are aware that even a minor delay is detrimental for the unit because the polymer formation of the carbonyl compounds is extremely rapid and takes place within few minutes. The one criteria for the above purpose is that the additive should be stable in the caustic solution for reasonably long duration. Referring to example 4 and 5 the inorganic salts like sodium dithionite and sodium metabislufite which are once added to the caustic solution have remained actively effective for preventing polymer formation even upto 20 days. This is very economical solution for scavenging of carbonyl compounds in petrochemical industries. For purposes of this invention, low molecular weight species may be defined as 2 or 3 repeating units of acetaldehyde where as high molecular weight polymer may be defined as polymer having greater than 3 repeating units of acetaldehyde. The following Examples are merely illustrative of some embodiments of the present invention and the manner in which it is can be performed and are not intended to limit the scope of the claimed invention in any way: Example 1 To an clean four necked round bottom flask equipped with a thermometer, stirrer and condenser is charged with caprolactam (18 g, 0.1593 mole), sodium hydroxide (7 g, 0.175 g) and 75.0 g water. The mixture is well agitated and heated to 105°C to 120°C for a period of six hours. Small samples are periodically withdrawn and checked for conversion using HPLC. The conversion of epsilon caprolactam to six amino hexanoic acid is greater than 75%. Example2 20 ml of 10% NaOH solution are added to a 50 ml stoppered conical flask. To this is added the desired inhibitor in solution or in solid form, followed by the addition of 1 ml vinyl acetate. The mixture is shaken well and kept in an oven for 24 hrs at _55°C. One blank is prepared wherein all reagents except the inhibitor are added. At the end of 24 the contents of the flask are visually checked for clarity or any deposits, and UV readings are measured. The results are shown in Table 1 below. The results are average of two to three readings in all the tables. Table 1 Before polymerization : Use of single inhibitor compounds ( Polymer inhibition) Expt no Compounds gms Mole ratio % transmittance at 800 nm Absorbance at 720 nm Observation 1 Blank nil nil 0.5 2.5 Red hazy liquid with precipitate 2 Sodium dithionite 0.2075 0.125 68.5 0.2575 Red slightly hazy liquid 3 Sodium dithionite 0.4715 0.250 89.55 0.0475 Red clear liquid 4 Sodium dithionite 0.943 0.5 90 0.042 Faint red clear liquid 5 Sodium dithionite 1.886 1.0 80.35 0.09 Colorless liquid 6 . Sodium metabisulphite 0.1281 0.0625 0.466 2.54' Red hazy liquid 7 Sodium metabisulfite 0.2562 0.125 80.7 0.179 Red clear liquid 8 Sodium metabisulfite 0.549 0.25 86.4 0.113 Red clear liquid 9 Sodium metabisulfite 2.089 1.0 87.3 0.066 Red clear liquid 10 Sodium bisulfite 0.140 0.125 2.8 1.80 Hazy red liquid 11 Sodium bisulfite 0.338 0.30 86.1 0.133 Red clear liquid 12 Sodium bisulfite 0.563 0.50 86. 0.1035 Red clear liquid 13 Sodium bisulfite 1.127 1.0 89.1 0.092 Red clear liquid 14 Sodium sulfite 0.170 0.125 0.35 2.653 Red hazy liquid 15 Sodium sulfite 0.682 0.5 83.6 0.130 Red clear liquid 16 Sodium sulfite 1.365 1.0 89.2 0.08 Red clear liquid 17 Sodium sulfate 1.539 1.0 5.9 1.904 Hazy liquid with gummy polymer 18 Sodium hydrogen sulfate 1.496 1.0 4.4 1.332 Same as above Table 3 Before polymerization: Use of blends (Polymer Inhibition) Expt no Compounds Gms Moles of Moles of Total moles % transmittance at 800nm Absorbance at 720 nm Observation 1 Sodium Dithionite 0.1 o.i 18.5 0.842 Red hazy liquid 2 Amino caproic acid 0.0372 0.026 0.026 0.3 2.571 Closer to blank 3 Sodium Dithionite + Amino caproic acid 0.1886 0.0372 0.1 0.026 0.126 82 0.183 Red clear transparent liquid 4 Sodium dithionite + Product of Example 1 0.1886 0.09ml 0.1 0.026 0.126 81.0 0.210 Red clear transparent liquid 5 Sodium dithionite + sulfanilic acid 0.1886 0.3 0.1 0.160 0.260 86.7 0.1195 Red clear transparent liquid 6 Sulfanilic acid 0.30 0.160 0.160 0.2 2.872 Red brown hazy with particles 7 caprolactam 0.3673 0.3 0.3 0.4 2.783 Dark red slight hazy liquid with some dispersed particles Expt no Compounds Gms Moles of Moles of Total moles % transmittance at 800nm Absorbance at 720 nm Observation 8 Caprolactam + sodium dithionite 0.1836 0.1886 0.1 0.15 0.250 82.9 0.176 Red clear transparent liquid 9 Sodium meta bisulfite + sodium dithionite 0.1853 0.1866 0.1 0.09 0.190 93.3 0.067 Faint Red clear transparent liquid 10 Sodium dithionite + Amino caproic acid 0.1132 0.0888 0.06 0.0625 0.123 81 0.285 Red clear transparent liquid 11 Amino caproic acid 0.0888 0.0625 0.0625 0.3 2.872 Same as blank 12 Sodium metabisulfite 0.09 35 Red hazy liquid with polymer particles Example3 20 ml of 10 % NaOH solution is pipetted into a 50 ml stoppered conical flask. To this is added 1 ml of vinyl acetate solution. The mixture is shaken well and kept in oven for 15 minutes. During this period, the vinyl acetate is hydrolyzed and polymerizes to form insoluble products. After 15 minutes the desired amount of inhibitor is added. One control sample is prepared without inhibitor. The flask is shaken well and kept in an oven for 24 hours. After 24 hours the flask is checked visually for clarity and any deposits. In some cases UV transmittance is measured for comparison. The results are shown in Table 2 given below. Table 2 After polymerization (Dissolution of Polymer) Expt no Compounds gms moles Moles of Total moles % transmittance at 800nm Absorbance at 720 nm Observation 1 blank nil nil nil nil 0.5 2.5 Red turbid liquid with polymer particles 2 Sodium Dithionite 0.943 0.5 0.5 62.5 0.202 Yellow clear liquid with few particles 3 Amino caproic acid 0.125 0.087 0.087 0.5 2.709 Same as above 4 Sodium Dithionite + Amino caproic acid 0.943 0.125 0.5 0.0879 0.5879 77.05 0.1125 Red clear transparent liquid 5 Sodium dithionite + Product of Example 1 0.943 0.3ml 0.5 0.087 0.5879 85.7 0.07 Red clear transparent liquid 6 caprolactam 0.3673 0.3 0.3 11.4 1.095 Hazy red liquid with particles Expt no Compounds gms moles Moles of Total moles % transmittance at 800nm Absorbance at 720 nm Observation 7 Sodium dithionite + caprolactam 0.943 0.3673 0.5 0.3 0.8 69.7 0.171 Clear red liquid with few particles 8 caprolactam 0.6122 0.5 0.5 64.0 0.387 Dark red liquid with few particles 9 caprolactam 1.224 1.0 1.0 70.0 0.315 Red clear liquid 10 Sodium bisulfite 1.127 1.0 1.0 10.7 Brown hazy liquid with heavy polymer particles 11 Sodium metabisulfite 1.0 1.0 1.0 18.7 0.729 Brown hazy liquid with heavy polymer particles 11 Sodium sulfite 1.365 1.0 1.0 4.3 1.389 Brown hazy liquid with heavy polymer particles Caustic Solution Stability 0.3 mole strength of sodium dithionite was prepared in 10 % NaOH solution. The performance of this sodium dithionite solution was tested periodically. To 20 ml of the solution 1 ml vinyl acetate was added and shaken well. The flask was kept in the oven at 55 deg c for 24 hrs. The details of the result are listed in the Table 4 given below Table 4 Sr no Hours % transmittance Absorbance @ 720 Observation 1 24 hrs 90.3 0.122 Red clear transparent liquid 2 192 85.3 0.145 Red clear transparent liquid 3 240 87.9 0.140 Red clear transparent liquid 4 360 90.9 0.129 Red clear transparent liquid 5 480 87.3 0.142 Red clear transparent liquid Sodium Metabisulfite 0.2 mole strength of sodium dithionite was prepared in 10 % NaOH solution. The performance of this sodium dithionite solution was tested periodically. To 20 ml of the solution 1 ml vinyl acetate was added and shaken well. The flask was kept in the oven at 55 deg c for 24 hrs. The details of the result are listed in the Table5 given below Table 5 Sr no Hours % transmittance Absorbance @ 720 Observation 1 24 hrs 90.7 0.095 Red clear transparent liquid 2 72 90.8 0.109 Red clear transparent liquid 3 168 90.3 0.105 Red clear transparent liquid 4 216 88.7 0.118 Red clear transparent liquid 5 336 90.4 0.116 Red clear transparent liquid While the present invention has been described herein in terms of various embodiments one of ordinary skill in the art will recognize that modification to the embodiments can be made without departing from the scope of the claimed invention. While the above description contain many specificities these should not be construed as limitations in the scope of the invention but rather as exemplifications of different embodiments thereof Accordingly the scope of the invention should be determined not by embodiment illustrated but by appended claims and their legal equivalents. We claim: 1. A method of removal of carbonyl compounds along with acid gases from cracked gases in ethylene process occurring ih a caustic wash unit, comprising a step of: introducing premixed additives and aliphatic amino acids into a feed stream of caustic wash unit, an effective amount of an additive comprising of sodium dithionite salts and of sodium metabisulfite and/or a combination thereof with an aliphatic / aromatic amino acid, or lactam, in a molar ratio of 0.5: 1.01 to 1: 25 more preferably 1: 1 to 1: 0.01 mole, wherein the mixture is agitated and heated to temperature within range from 105 °C to 120 °C for a period of six hours, 2. A method, as claimed in claim 1, wherein said aliphatic amino acid is selected from the group of consisting of amino hexanoic acid, amino caproic acid, glycine, taurine, beta alanine, NH2(CH2)xYOzOH and isomers thereof, preferably any one of said 6 amino hexanoic acid and said amino caproic acid, 3. A method, as claimed in claim 1, wherein, said lactam is selected from the group consisting of epsilon caprolactam, isomers of said epsilon caprolactam and substituted derivatives of epsilon caprolactam, preferably said epsilon caprolactam, 4. A method, as claimed in claim 1, wherein, said aromatic amino acid is selected from the group consisting of a sulfanilic acid, a derivative having any of the three structures comprising (HOOZ)w - PH -(CH2)xNH2, where x = 1 to 6, Z = C or heteratom 5, W = 1 to 4, and PH is phenyl ring; [(HOOZ) - (CH2)x]w - PH - (CH2)yNH2, where X = 1 to 5, W = 1 to 5, Z is C or heteroatom 5, W = 1 to 4 and PH is phenyl ring; and (HOOZ)w - PH(NH2)x where X = 1 to 5, Z = C or heteroatom 5, W = 1 to 5 and PH is phenyl ring, preferably said sulfanilic acid, 5. A method, as claimed in claim 1, wherein, molar ratio of carbonyl compounds to said additive is in the range from 1 : 0.01 to 1:25, preferably in the range from 1:0.01 to 1:3, 6. A method, as claimed in claim 1, wherein, said additive is used neat or in solution form, 7. A method, as claimed in claim 1, wherein, said effective amount of said additive is added to said feed stream in a single dosage or a plurality of periodic dosage, 8. A method, as claimed in claims 1 to 7, wherein, said additive is introduced into said feed stream before, or at the same time, or after said feed stream enters said caustic wash unit, and said caustic wash unit comprises a caustic scrubber, or an amine scrubber,, 9. A method, as claimed in claim 1, wherein, said aliphatic amino acid has a structure selected from the group consisting of straight chain structure, branched structure, cyclic structure, isomeric structure of the any of the preceding three structures, 10. A method, as claimed in claim 1, wherein, said aliphatic amino acid has at least one group from carboxyl group and sulfoxyl group or alternatively has a combination of a plurality of amine group and a plurality of carbonyl or sulfoxyl group, 11. A method, as claimed in claim 1, wherein, said aliphatic amino acid or said aromatic amino acid is used neat or as a salt, 12. A method, as claimed in claim 1, wherein the additives and amino aliphatic groups are added as a blended form or individual component in a clear solution form, 13. A method, as claimed in claim 1, wherein, molar ratio of said sodium dithionite to the other compound used in each of the combinations, is preferably 1:0.17 to 1:1.5, 14. A method of removal of carbonyl compounds along with acid gases from cracked gases in ethylene process, substantially as herein described and illustrated in examples Dated this 22nd day of December, 2004. To, The Controller of Patents, Patent Office Mumbai Branch, Mumbai. Mr. Sharatchandra Dattatarya Tase Patent Agent for the Applicant Registration No. IN/PA 879

Documents:

749-mumnp-2004-abstract(25-07-2007).doc

749-mumnp-2004-abstract(25-07-2007).pdf

749-mumnp-2004-cancelled pages(25-07-2007).pdf

749-mumnp-2004-claims(granted)-(25-07-2007).doc

749-mumnp-2004-claims(granted)-(25-07-2007).pdf

749-MUMNP-2004-CORRESPONDENCE(1-4-2011).pdf

749-mumnp-2004-correspondence(25-07-2007).pdf

749-mumnp-2004-correspondence(ipo)-(27-07-2007).pdf

749-mumnp-2004-form 1(22-12-2004).pdf

749-mumnp-2004-form 19(22-12-2004).pdf

749-mumnp-2004-form 2(granted)-(25-07-2007).doc

749-mumnp-2004-form 2(granted)-(25-07-2007).pdf

749-mumnp-2004-form 26(22-12-2004).pdf

749-mumnp-2004-form 3(09-07-2007).pdf

749-mumnp-2004-form 3(22-12-2004).pdf

749-mumnp-2004-pct-ipea-409(22-12-2004).pdf

749-MUMNP-2004-PETITION UNDER RULE 138(1-4-2011).pdf