Patent GB-721924-A (GB)
Title: Steam generation and compositions for improving steam quality
Inventor: JOHNSON CARL ERICK
IPC: B01B1/04
Filed: 1952-08-26
Abstract: The production of foam in, and the priming of steam generators operating under superatmospheric pressures is minimized by incorporating with the water a minor quantity of a diether of a polyoxyalkylene glycol characterized by an average molecular weight of at least 500 and a chemical structure in which the polyoxyalkylene chain contains at least one oxymethylene group of the formula <FORM:0721924/IV (a)/1> where A or B or both may be alkyl, aryl or aralkyl radicals.  The preferred ethers fall into four groups:-  (1) General formula RO[CE2O(CnH2nO)x]y CE2O(CnH2nO)xCE2OR1, wherein R and R1 may be alkyl, aryl or aralkyl radicals, E is hydrogen or an alkyl or aryl radical, n is 2 or more and may have several values in the same compound, x is 2 or more and y is 0 or more. These compounds may be prepared by reacting an alcohol with a polyoxyalkylene glycol and an aldehyde or ketone (e.g. <FORM:0721924/IV (a)/2> or by converting a polyoxyalkylene glycol to the corresponding dichloromethyl ether with formaldehyde and hydrogen chloride and then reacting said ether with an alcohol.  Suitable catalysts for these and the corresponding reactions producing ethers in groups (2)-(4) are, e.g., sulphuric acid, hydrochloric acid, ferric chloride, aluminium chloride, stannic chloride and zinc chloride used in 0.3-1 per cent by weight of the total reactants. Suitable dehydrating solvents are benzene, toluene and xylene and the dehydration is hastened by operating under vacuum or by gasification with, e.g., air, nitrogen or carbon dioxide, and suitable reaction temperatures are 50-150 DEG  C.  The following reactants are specified: dodecanol, polyoxyethylene glycol (400) and trioxymethylene; dodecanol polyoxyethylene glycol (400) and acetaldehyde; hexadecanol, polyoxypropylene glycol (400) and trioxymethylene; dodecanol, polyoxyethylene glycol (600) and trioxymethylene; hexadecanol, polyoxyethylene glycol (1000) and trioxymethylene; dodecanol, polyoxyethylene glycol (1540) and trioxymethylene; hexadecanol, polyoxyethylene glycol (1540) and trioxymethylene; hexadecanol, polyoxyethylene glycol (600) and trioxymethylene; hexadecanol, polyoxypropylene glycol (750) and trioxymethylene; hexadecanol, polyoxypropylene glycol (1200) and trioxymethylene; dodecanol, polyoxyethylene glycol (300) and trioxymethylene; hexadecanol, polyoxyethylene glycol (400) and benzaldehyde; dodecanol, polyoxyethylene glycol (1000) and acetone; dodecanol, polyoxyethylene glycol (1000) and propanol; dodecanol, polyoxyethylene glycol (1000) and butanal; dodecanol, polyoxypropylene glycol (750) and phenylacetaldehyde; hexadecanol polyoxyethylene glycol (400) and methyl ethyl ketone, and in examples, octyl alcohol, polyoxyethylene glycol (900) and trioxymethylene; and hexadecanol, polyoxyethylene glycol (400) and trioxymethylene are used.  The figure in brackets refers to the average molecular weight of the glycol.  The aliphatic alcohol should contain at least 12 carbon atoms and the polyoxyalkylene glycol 7 oxyalkylene groups.  The method is particularly suitable with low molecular weight alcohols, e.g. methyl, ethyl and propyl and alcohols such as phenoxyethanol or phenylethanol.  Preferably the product has a molecular weight between 2000 and 5000.  (2) General formula RO(CnH2nO)xCE2OR1, where R, R1, E, n and x have the same significance as before.  These compounds may be prepared by reacting an alcohol with a monoether of a polyoxyalkylene glycol and an aldehyde or ketone (e.g. C4H9OH+C4H9O (CnH2nO)xH+HCHO --> C4H9O (CnH2nO)x CH2OC4H9, where C4H9O(CnH2nO)xH is the monobutyl ether of a polyoxyalkylene glycol containing oxyethylene and oxypropylene groups in approximately 1 : 1 ratio and random arrangement, with a molecular weight of approximately 1000).  The following reactants are also specified: benzyl alcohol, the aforesaid monoether and trioxymethylene (example given); dodecanol, the aforesaid monoether and acetaldehyde; hexadecanol, monobutyl ether of polyoxyethylene glycol (750) and trioxymethylene; octanol, polyoxypropylene glycol (3000) monobutyl ether and acetone; dodecanol, polyoxypropylene glycol (1000) monobutyl ether and benzaldehyde.  The total molecular weight of the compound should be at least 1000 and neither R nor R1 should contain less than 4 carbon atoms.  (3) General formula RO(CnH2nO)xCE2O (CnH2nO)xR1, where R, R1, E, n and x have the same significance as before.  Synthesized, e.g. by the reaction:-2C4H9O(CnH2nO)xH+HCHO --> <FORM:0721924/IV (a)/3> wherein the monoether is the same as that described under (2) above (in an example HCHO is replaced by trioxymethylene), or 2C16H33O(C4H8O)3H+HCHO --> <FORM:0721924/IV (a)/4> Other aldehydes and ketones may be used, and the molecular weight of the product should be at least 500 when R and R1 contain 12 or more carbon atoms and preferably at least 1000, when R and R1 are smaller, e.g. having 4 carbon atoms.  (4) General formula RO(CnH2nO)xCE2O (CnH2nO)zCE2O (CnH2nO)xR1, where R, R1, E and x have the same significance as before and z is 2 or more. Synthesized, e.g. by the reaction: <FORM:0721924/IV (a)/5> <FORM:0721924/IV (a)/6> wherein the monoether is that referred to above, and the polyoxyethylene glycol has an average approximate molecular weight of 6000.  (In an example HCHO is replaced by trioxymethylene). This synthesis is particularly suitable for use with commercially available polyoxyalkylene glycols.  In an alternative synthesis, the dichloromethyl ether referred to in (1) above may be reacted with a monoether to produce a diether falling into group (4).  The preferred compounds according to the invention are those, produced by reaction of an aldehyde or ketone with a monohydric alcohol and a polyoxyalkylene glycol or monoether thereof, which are at least partially soluble in water at, say, 75 DEG  F., and become substantially insoluble at steam generating temperatures. Specification 659,925 is referred to.ALSO:The production of foam in, and the priming of steam generators operating under superatmospheric pressures is minimized by incorporating with the water a minor quantity of a diether of a polyoxyalkylene glycol characterized by an average molecular weight of at least 500 and a chemical structure in which the polyoxyalkylene chain contains at least one oxymethylene group of the formula <FORM:0721924/IV (b)/1> where A or B or both may be alkyl, aryl or aralkyl radicals.  The preferred ethers fall into four groups:  (1) General formula RO[CE2O(CnH2nO)x]y CE2O(CnH2nO)xCE2OR1, wherein R and R1 may be alkyl, aryl or aralkyl radicals, E is hydrogen or an alkyl or aryl radical, n is 2 or more and may have several values in the same compound, x is 2 or more and y is 0 or more. These compounds may be prepared by reacting an alcohol with a polyoxyalkylene glycol and an aldehyde or ketone (e.g. 2C8H17OH+12HO(C2H4O)20H+ 13HCHO --> C8H17O[CH2O(C2H4O)20]11 CH2O (C2H4O)20CH2O C8H17 and 2C16H33OH+HO (C2H4O)9H+2HCHO --> C16H33O CH2O(C2 H4O)9CH2OC16H33) or by converting a polyoxyalkylene glycol to the corresponding dichloromethyl ether with formaldehyde and hydrogen chloride and then reacting said ether with an alcohol.  Suitable catalysts for these and the corresponding reactions producing ethers in groups (2)-(4) are, e.g., sulphuric acid, hydrochloric acid, ferric chloride, aluminium chloride, stannic chloride and zinc chloride used in 0.3-1 per cent by weight of the total reactants. Suitable dehydrating solvents are benzene, toluene and xylene and the dehydration is hastened by operating under vacuum or by gasification with, e.g., air, nitrogen or carbon dioxide, and suitable reaction temperatures are 50-150 DEG  C.  The following reactants are specified: dodecanol, polyoxyethylene glycol (400) and trioxymethylene; dodecanol, polyoxyethylene glycol (400) and acetaldehyde; hexadecanol, polyoxypropylene glycol (400) and trioxymethylene; dodecanol, polyoxyethylene glycol (600) and trioxymethylene; hexadecanol, polyoxyethylene glycol (1000) and trioxymethylene; dodecanol, polyoxyethylene glycol (1540) and trioxymethylene; hexadecanol, polyoxyethylene glycol (1540) and trioxymethylene; hexadecanol, polyoxyethylene glycol (600) and trioxymethylene; hexadecanol, polyoxypropylene glycol (750) and trioxymethylene; hexadecanol, polyoxypropylene glycol (1200) and trioxymethylene; dodecanol, polyoxyethylene glycol (300) and trioxymethylene; hexadecanol, polyoxyethylene glycol (400) and benzaldehyde; dodecanol, polyoxyethylene glycol (1000) and acetone; dodecanol, polyoxyethylene glycol (1000) and propanal; dodecanol, polyoxyethylene glycol (1000) and butanal; dodecanol, polyoxypropylene glycol (750) and phenylacetaldehyde; hexadecanol polyoxyethylene glycol (400) and methyl ethyl ketone, and in examples, octyl alcohol, polyoxyethylene glycol (900) and trioxymethylene; and hexadecanol, polyoxyethylene glycol (400) and trioxymethylene are used.  The figure in brackets refers to the average molecular weight of the glycol.  The aliphatic alcohol should contain at least 12 carbon atoms and the polyoxyalkylene glycol 7 oxyalkylene groups.  The method is particularly suitable with low molecular weight alcohols, e.g. methyl, ethyl and propyl and alcohols such as phenoxyethanol or phenylethanol.  Preferably the product has a molecular weight between 2000 and 5000.  (2) General formula RO(CnH2nO)xCE2OR1, where R, R1, E, n and x have the same significance as before.  These compounds may be prepared by reacting an alcohol with a monoether of a polyoxyalkylene glycol and an aldehyde or ketone (e.g. C4H9OH+C4H9O (CnH2nO)xH+HCHO --> C4H9O(CnH2nO)x CH2OC4H9, where C4H9O(CnH2nO)xH is the monobutyl ether of a polyoxyalkylene glycol containing oxyethylene and oxypropylene groups in approximately 1 : 1 ratio and random arrangement, with a molecular weight of approximately 1000).  The following reactants are also specified: benzyl alcohol, the aforesaid monoether and tri