US1728213A - Manufacture of sulphuric acid - Google Patents

Description

MANUFACTURE OF SULPHURIC ACID Filed April 29, 1926 COOLER ABSORBER INVENTOR fiE/V/P/F Mf/PAMM BY 7 6 g ATTORNEY Patented Sept. 17, 192% satire stares PATENT OFFICE HENRY F. MERRIAM, OF WEST OBANGE, NEW JERSEY, ASSTGNOR TO GENERAL CHEMICAL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK MANUFACTURE OF SULPHURIG ACID Application filed April 29, 1926. Serial No. 105,344.

My present invention relates to the manufacture of sulphuric acid and particularly to the contact process for the production of such acid by the catalytic action of certain substances on a gaseous mixture containing sulphur dioxide and oxygen. The invention has for its object the provision of a system characterized by decreased corrosion of the equipment and marked economies in operation, as more fully pointed out hereinafter. The importance of purifying the gases employed in the manufacture of sulphuric acid has been realized for some time and 'various attempts have been made to deprive the gases of certain impurities before bringing them in contact with the catalytic agent. More particularly the removal of moisture from the air or other oxygen-com taining gas by means of sulphuric acid as a drying agent has been resorted to heretofore. The older practice employed for this purpose consisted in drying the burner gases after a scrubbing and filtering treatment and then passing such gases through a compressor to deliver them to the contact chambers with the proper excess of oxygen to enable the sulphuric anhydride to be formed. In the more recent practice in which sulphur dioxide gases are produced from Louisiana brimstone and passed to the contact chambers without a cold purification treatment, the air used for combustion is dried by means of sulphuric acid and then passed through a compressor to deliver it to a burner in which sulphur dioxide gases are produced, said gases being then passed on to the contact apparatus. The difliculty with both practices is that the gases, in their passage through the drier, will inevitably pick up some of the drying agent and carry it into the compressor or blower, and since the latter is made of material attacked by sulphuric acid,'the corrosive action of the 4 sulphuric acid onthe compressor will in time impair very materially the eificiency of such apparatus. Particularly when the compressor was of the rotary or blower type, corrosion resulted in an increase of clearances which finally became so great as to require replacement of the blowers or at least of their main portions.

Other possible places to put the blower or compressor are following the absorber, or between the burner and converter. The difliculty with the first mentioned position is the same as that existing when the blower is placed following the drier,.namely corrosion of the blower resulting from sulphuric acid carried over from the absorber. The second mentioned position has the obviously great disadvantage of requiring the blower to handle exceedingly hot sulphurous gases; not only necessitating a blower of greatly increased capacity to handle the greater volume of gas due to its increased temperature, but also imposing severe operating conditions.

In order to avoid these difliculties, I have devised the present process and apparatus,

according to which the air is compressed before its admissionto the drier. Thus, the acid picked up by the gases during their passage through the drier cannot reach the blower and the latter remains in serviceable condition for a practically indefinite length of time. Any sulphuric acid picked up by the gases during their passage through the drier is conducted at once to the burner where such acid is not liable to produce any detrimental effects. The blower or compressor when operating in accordance with my invention is running at a temperature lower than that obtaining at any other point in the system, thus permitting a blower of minimum size to be used and reducing operating costs.

In the accompanying drawing, a plant suitable for the carrying out of the present asbestos to remove impurities such as dust and also certain other impurities, for instance oil, which may get into the air within the blower from the lubricated bearings of the blower shaft. D indicates a drier omitted, the outlet of the blower being in that event connected directly with the inlet of the drier. From the outlet of the drier the air or other oxygen-containing gas passes through a conduit F to a sulphur burner or combustion chamber G of'any suitable construction. The outlet ofthis burner. is connected by a conduit H with a cooler I from which a conduit J leads to a converter K of the type for converting amixture of sulfur dioxide gas and oxygen intqsulphuric anhydride. This sulphuric anhydride, with inert gases" if present, then passes through a conduit, L to a cooler M and then through another conduit N to an absorber 0 from the outlet P of which the resulting liquid, sulphuric acid, is conducted to storage or other place of disposal, the unabsorbed gases escaping at Q.

The air or other oxygen-containing gas is under pressure throughout the process from the outlet of the blower A to the final exit Q, of the absorber. Dust or like 'impurities and also an lubricating oil that the air may have ta en up in the blower are eliminated in the filter B. As sug ested above however, if the air is origin'a y of great purity, the filter B may be omitted. The compressed air then enters the drier D and is there deprived of its moisture. The dry air then proceeds to the burner Gin which elemental sulphur or brimstone is burned with oxygen to roduce sulfur dioxide gases in any wellown or approved manner itbeing understood that an excess of oxygen is present'so thatthe gases passing outat H contain sulphur dioxide and oxygen in proper proportion for their subsequent conversion into sulphuric anhydride "by the catalytic reaction taking place in the converter K, wherein the oxidation of the sulphur to sulphur trioxide is completed. Any

sulphuric acidwhich the gases may pick up during their passage through the drier D will pass on directly to theburner G. The reaction occurring in ths part of the apparatus is such that the resence of the small amount of sulphuric acid in the gases will not be objectionable. It will be noted .that, contra to the practice hitherto, the sulp uric acid icke up in the drier is not allowed to reac the blower, and the detrimental corrosive efiect of the sulphuric acid on the blower is thus efliciently avoided. considerable saving in the repair costs and depreciation is effected by using thepresent invention. The fact that a positive pressure is employed during the entire treatment is also of considerable value in that the volume of gases under treatment is materially re-. oduceds The sulphuric acid employedms a drying agentmay be of 98% concentration or its strength may be only from 60 Be.

to'66 B..

It be appreciated that my invention is of particular value in connection with that modification of the contact process previously described herein in which sulphurous gases are produced from sulfur of the Louisiana type and then passed without material lowering of their temperature below the eflfective conversion temperature of S0 to S0, to contact chambers containing a platinum type of contact material. In this modification no moisture is introduced into the system, as is done, when using the old cold purification treatment of the burner gases, and consequently the moisture content of the entiresystem is lowered by placing the drying equipment at the beguming of the system.

It will, of course, be understood that my invention would be applicable with the same success if any other drying agent having corrosive properties should be used instead of sulphuric acid since the generic efiect of preventing corrosion of the compressor parts would still be obtained, and I desire it to be understood that any corrosive agent having the property of removing moisture from air or similar gases is to be considered an equivalent of sulphuric acid for the purpose of drying and that the appended claims are to be interpreted accordingly.

I claim:

1. Thei improvement in the process of manufacturing sulphuric anhydride which consists in initially compressing air withdrawn at atmospheric conditions from the atmosphere, utilizing said compressed air for the oxidation'of sulphur bearing material to produce a sulphur dioxide gas and then treating said gas toproduce sulphur trioxide. i

2. The improv ent in the process of manufacturing sulphuric anhydride Sin which dried oxygen containing gas is utilized for oxidation of the sulphur material to produce a sulphur dioxide gas which consists in compressing said gas before drying it. I

3. In the manufacture of sulphuric acid, that improvement which consists in compressing an oxygen-bearing gas, drying the compressed gas by contact with sulphuric acid, then burning sulphur-containing material in'contact with such compressed dried gas, and converting the resulting sulphurous A gases into sulphuric acid.

4. In the manufacture of sulphuric acid,

that improvement which consists in compressing an oxygen-bearing gas, drying the compressed gas by contact with sulphuric acid and then utilizing the resulting gas for the oxidation of elemental sulphur to form sulphuric anhydride.

5. The process which consists in compressing an oxygen-bearing gas, removing impurities from the compressed gas by filtration, then drying such compressed gas by -contact with sulphuric acid,--thereupon burning sulphur-containing material in contact with such compressed dried gas, and converting the resulting sulphurous gases into sulphuric acid.

6. In the manufacture of sulphuric acid, that improvement which consists in compressing an oxygen-bearing gas, drying said gas by contact with sulphuric acid, utilizing said dried gas for the oxidation of sulphur of the Louisiana type to sulphur dioxide and then passing said sulphur dioxide gas, without material lowering of its temperature below the conversion temperature of SO to S0,, in contact with a catalyst for the conversion ofthe SO to S0,.

7 In the'manufacture of sulphuric acid, that improvement which consists in compressing an oxygen-bearing gas, drying said gas by contact with sulphuric acid, utilizing said dried gas for the oxidation of sulphur of the Louisiana type to sulphur dioxide and then passing said sulphur dioxide gas, without material lowering of its temperature below the conversion temperature of SO to S0,, in contact with a platinum type of gaalyst for the conversion of the S0 to 8. An apparatus for the manufacture of sulphuric acid, comprising a compressor, a drier the inlet of which is connected with the outlet of the compressor, a burner the inlet of which is connected with the outlet of the drier, and a plant for converting sulphurous gases into sulphuric acid, the inlet of said plant being connected with the outlet of said burner.

into sulphuric acid, the inlet of said plant being connected with the outlet of said burner.

10. In the manufacture of sulphuric acid,

that improvement which consists in compressing an oxygen-bearing gas, drying the compressed gas by contact with sulphuric acid, then burning sulphur-containing material in contact with such compressed dried gas, and passing the resulting sulphurous

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