DE1940168A1 - Process for the production of sulfur trioxide - Google Patents

Description

Baa isehe Anilin- & Soda-Fabrik AG 1940168

Our reference: o.Z. 26 312 Kl / Ot. . 6700 Ludwigshafen, 5.8 »1969

Process for the production of sulfur trioxide

The production of sulfur trioxide takes place in technical ' Scale by reacting sulfur dioxide with excess Oxygen in the presence of catalysts according to the equation

SO ₉ + 1 / 2O ₉ SO, -21.9 kcal.

This reaction is exothermic and also strongly dependent on temperature. The catalyst used today is almost exclusively vanadium contact compound, which has replaced the previously expensive platinum catalysts that were very sensitive to contact poisons. The catalytic conversion takes place in several resting layers. The sulfur dioxide-containing gases occur in today's conventional method at a concentration of 8 to 10 vol.% SOP, and with a temperature of about 45O ⁰ C in the first contact compound layer and be converted there to about 60 #, maintaining the temperature at 620 ¹ to 63O ⁰ C increases. A higher conversion is not possible because of the temperature dependence of the S0 ₂ / S0, equilibrium. The gases must therefore be cooled first again on eg 45O ⁰ C. Extensive heat exchangers are required for this. After cooling down, flow through! the gases can be done to increase sales to more than $ 85> in the warming to about 55O ⁰ C, the second contact layer mass. After cooling in a further WärmeauetauschersysteiD to example 420 ⁰ C, in a third contact mass layer has an increase in turnover, for example about 96 ^, wherein itioeh a small temperature increase of about 30 ⁰ C occurs dlje in a third heat exchange veraich- · is tet, so that the gases finally with again 420 ⁰ C in the

the fourth and last contact mass layer occur, in which a final conversion of over $ 98> is reached which comes close to the temperature equilibrium.

I «.let leiäht'eiasüethtn, 06 ditacr working method considerably®

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Requires investment costs and close monitoring in order to to achieve the desired final sales. In particular, the Construction of the furnace, care must be taken that the temporal removal of the gases and their reintroduction takes place in such a way that that the even flow of the gases over the cross-section and through the various contact mass layers is not is impaired, as otherwise the possible final sales cannot be achieved.

Instead of indirect cooling in heat exchangers, between the individual contact ground layers also have a direct one Cooling by adding. cold gases, e.g. cold air. Besides being a perfect blending of large Quantities of hot gases with small quantities of cold gases forms a particular technical problem, this measure leads to a Volume increase, which causes increased costs in the subsequent SO, absorption system and possibly also in the air drying system. This will make up a large part of the savings by at least partial elimination of the heat exchanger again consumed.

Recently, a previously described procedural principle has been taken up again and put into practice. In this so-called double catalysis process, the gases are fed to an intermediate absorption after they have passed the third contact mass at a conversion of about $ 90 to $ 93. By associated with this measure, displacement of the SOP / SO ~ - balance or the Og / SOG ratio, it is possible to implement the residual gases after reheating in a fourth contact ground layer 98 io, so that the overall conversion 99 '8 # amounts. This process has achieved great importance with regard to the requirements with regard to keeping the air clean and is also economically justifiable due to the better yield despite higher investments. However, it does not change the fact that the conversion of sulfur dioxide to sulfur trioxide is expensive and places special demands on the designer and operator of the contact furnace.

It is also known to react with sulfur dioxide

109809/1691 - 3 -

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Make oxygen on fluidized contacts. Instead of sulfur dioxide, sulfur can also be used, the sulfur dioxide formed as an intermediate by combustion of the elemental sulfur being converted to sulfur trioxide by the excess oxygen. The reaction is carried out at temperatures of about 320 to 59 ° C ^0. The temperature in the fluidized bed is regulated by circulating the catalyst masses, in that the mass is cooled outside the fluidized bed and the cooled catalyst mass is returned to the fluidized bed with air. In the normally employed temperatures of about 420 ⁰ C only the usual sales are achieved von'98 to 98.5 #, also in this method. At lower and higher temperatures, low conversions are obtained, since the activity of the catalyst decreases at lower temperatures or, at higher temperatures, the equilibrium of the reaction is shifted in an unfavorable direction.

The object of the present invention was the implementation of sulfur or sulfur dioxide with oxygen in a layer kept in swirling up and down motion with these gases from catalysts for the oxidation, from sulfur dioxide to sulfur trioxide at elevated temperatures and with the removal of the the implementation of the heat generated so that you can get higher Can generate sales of # 99 and above.

It has been found that this object can be achieved if the Tempe-? temperature at the gas inlet of the fluidized bed at 480 to 650 ⁰ C and the temperature at the gas outlet of the fluidized bed at 350 to 420 ⁰ C keeps.

Surprisingly, the procedure according to the invention succeeds in achieving higher conversions compared to the known procedure, in which a uniform temperature is maintained within the fluidized bed, although temperatures are used in the process according to the invention which are partly higher and partly lower than those normally used for the reaction optimal ¹ temperatures, probability is found in the invention

-. 26 312

If the working method were to be sufficiently large, the catalyst should be sufficient. in - vertical ri clitinig instead of “in a lisse way” share ©. of Catalyst, äi © at "the lower" temperatures of the above- ~ Ren cable "of the fluidized bed lost its catalytic activity hsbtn, ia den, lower and hotter rope of a fluidized bed-s to be reactivated there su =

The compliance with the Senperatursn in the fluidized bed according to the invention takes place in a simple® manner by suitable arrangement öer lühleleaente «3It is to maintain the temperature gradient expediently about 20 "to $ 40 of the total cooling surfaces required in the middle third of the fluidized bed and $ 80 to $ 60 to be arranged in the upper third of the fluidized bed »-While im: nit © ~ No cooling takes place in the third third of the fluidized bed.

To achieve particularly high conversions it is _{zweckn5äßig}} fegeingang on the fluidized bed, that is, approximately in the lower third, 'a temperature of 500 to 61O ⁰ O and adjust the gas output ₅ ä «h. about in the upper third a temperature of 360 Ms 4-00 ⁰ C ■ must be maintained ». '.

In the case of _: grasses containing sulfur dioxide, eg rust gasses with a SOp-G content of 8 to 12 days. these are at a temperature of 200 to 35O ⁰ C in the fluidized bed was introduced in Palle the conversion of sulfur can this but also liquid or gas introduced into the fluidized bed "in solid loiw _9" who DENV "." - -.

AIa ■ Catalysts are known-tanadine catalysts ;, . öie_ in terms of size "- in © inar grain size - τση 0.1 to 3 ram.

■ In eiiiOEä WSelse] iio! Itres.ictor ^; Bit ^; -eineia JJiiroliiBeEses? from 2 960

and eiiiGv SMhQ of 11,000- as "" are eicli 10 n * -'Gineg'Tan katalyp ^ törs ffiit an Iförßimg "from O ₅ -SI) Is 2 IK ₆ Ιϊι the Wirlsel-ak'fe'or are Kühlroliro bü; ice cream - from "ins / gesa ^ at 21 et" Gin

BA © ORIGiIMAL

- 5 - ■ · ■■ - O.Z. 26 312

which are charged with circulating _{water 5} that is evaporated (saturated steam temperature 249 ⁰ O)

'2''' so that there is a total of about 7 m in the middle third and the remainder ± m in the upper third of the fluidized bed, which is 4,000 mm high in the whirled-up state. The lower part of the fluidized bed is not cooled "Hourly be 7 600 ar introduced a sulfur combustion gas with a content of 9 VOX ^ SO"und'einer temperature of 400 ⁰ C in the reactor.

Here arises in the lower part of the fluidized bed a temperature of about 580-610 ⁰ O, while the temperature in the upper part is approximately 56o ⁰ G. The conversion is 99s6 ^.

Example 2 -

A vortex reactor as described in Example T has cooling

2 elements with an effective area of 50 m in total,

■ 2 ■ · "■ '■ which are arranged _{9 so} that about 17 m are arranged in the middle third and the rest in the upper third of the fluidized bed, are * ^: ■;

Hourly 7 600 m air be at a temperature of 200 ⁰ C and 1000 kg © lementarer sulfur in liquid Porm ia the reactor 'introduced into the reactor "Under the same conditions as in Example 1 (temperature, catalyst) gives a" sales from $ 99.6>.

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Claims (2)

-6- 0 »Ζ. 26 512 "patent claims 1. Process for the production of sulfur trioxide by reaction * of sulfur dioxide and / or sulfur with oxygen or oxygen-containing gases in a layer of catalysts for the oxidation of sulfur dioxide to sulfur trioxide at elevated temperatures with removal, which is kept in swirling motion with these gases the heat generated during the conversion, characterized in that the temperature at the gas inlet of the fluidized bed is kept at 480 to 65O ⁰ C and the temperature at the gas "outlet of the fluidized bed at 350 to 420 ⁰ O through indirect cooling. 2. The method according to claim 1, characterized in that the temperature is maintained at the gas inlet of the fluidized bed at 500-610 ⁰ C. ^: 5 »Process according to claims 1 and 2, characterized in that the temperature at the gas outlet of the fluidized bed is kept at up to 400 ° C. Badische Anilin- & Soda-labrik AG