SE447378B - PROCEDURE FOR SULPHONATION OR SULFATING AND DEVICE FOR IMPLEMENTATION OF THE PROCEDURE - Google Patents

Description

The sulfonation reaction in thin layer apparatuses is currently obtained by means of a number of different systems. Thin layer sulfonation via a single subreactor (US-A-3,328,460).

This type of reactor, the first of which is used for thin-layer sulfonation, comprises a single cylindrical, vertically arranged tube, at the upper end of which a thin layer or a film of liquid reagent is fed, forced to travel downwards attached to the inside of the tube. Inside the tube, a stream of gaseous reactant is generally fed, consisting of gaseous sulfur trioxide diluted in an inert carrier gas. A coolant may circulate on the outside of the tube for the purpose of monitoring that the temperature of the mixture remains within predetermined limits during the reaction. The limitations associated with a single sub-reactor of this type are that the maximum diameter of the reactor (and thus its maximum production rate) is tied to the optimum feed rate for the gaseous reacting material.

As most of the reaction at the optimum gas velocity (20 - 80 m / s) takes place in a first very short part of the reactor, diameters (and corresponding production velocities) over 25 mm cause an unacceptable lowering of the cooling surface consisting of the tube. outside. This situation causes an increase in the maximum temperature of the reaction mass to an unacceptable value, whereby a product of poor quality is obtained (poor color due to the formation of oversulfonated by-products). I 2. Reactor with annular gas space. This type of reactor has two concentric, vertical and coaxial cylinders, one inner and one outer, which delimit an annular gas space.

The liquid reacting material is fed into both the inside of the outer cylinder and the outside of the inner cylinder.

By suitably selecting the ratio between the diameters of the two cylinders, it is possible to adjust the cross section of the reactor in a suitable manner, which cross section is formed by the surface of the ring delimited by the two cylinders. _ ._ __ ___ _._._..._: .........._.._._._._.____ A _ .. -.- .---> -V 447 378 However, this type of reactor also has some disadvantages.

If it is desired to increase the diameters of the two cylinders in order to increase the production capacity, serious difficulties arise with regard to the distribution of the liquid reacting material in the form of a film of constant thickness. This requires an extremely precise reactor design and consequently a significant increase in the manufacturing cost of the reactor.

In order to obtain an even distribution of the liquid reacting material on the reactor walls without having to resort to too high a precision in construction and assembly, in a modified type of this kind of reactor an annular rotor has been arranged in the upper part of the annular reactor. miga gas space.

However, this reactor only partially eliminates the above-mentioned disadvantages. In fact, at least for the upper part of this reactor, even higher precision is required in view of the presence of a rotating element, the distance of which from the two thin layers of reacting liquid material must be set very carefully. 3. Tube reactor (= multi-tube reactor ) (US-A-3,931,273 and US-A-3,918,917). This type of reactor consists of a bundle of single pipes, each of which has an optimal size with regard to the liquid distribution as well as the available cooling surface and the facilitation of the mechanical construction.

In these reactors the greatest difficulty lies in determining for each tube the exact amount of gas and liquid (equal for each tube) in order to obtain in each tube the same molar ratio between the reactants corresponding to that predetermined for the reactor.

Several authors have recently studied this problem and solved it in part through the following arrangements: a) the use of calibrated openings for the introduction of liquid and gas into each individual tube; b) use of tubes calibrated for the reaction, all of which have the same size: diameter, wall thickness, length; c) the use of a pressure relief gas introduced below the distribution nozzles to ensure the correct distribution of the reactants to the reactor tubes. 447 578 Although the arrangements listed above improve the operating conditions, they can not ensure a perfect molar ratio between the liquid and gaseous reactants in the individual tubes, but they provide acceptable results thanks to the already described advantages of using a multi-tube reactor. , where each individual tube when fed with the correct amounts of liquids guarantees the best operating conditions.

In this way, the best results that can be achieved are the statistical mean of more or less optimal values, which are obtained with any individual tube, although the molar ratio of gas / liquid in these tubes taken separately is no more than incidentally the optimal the value.

The precision of the gas / liquid ratio is obtained at the expense of a remarkable loss of pressure head, a phenomenon which also occurs in reactors with concentric tubes and causes, above all for the input of the gaseous reagent, a considerable energy consumption and design problem. in the upstream S03 manufacturing unit.

Against this background, the present invention aims to eliminate the above-mentioned disadvantages by means of a combination of elements, which have been developed and investigated for this purpose, ie: A) selection of solution in the tubes to ensure the best conditions in terms of heat exchange and homogeneity in film thickness.

B) Selection of the optimal size for the individual tubes to obtain the best compromise; maximum diameter (lower number of tubes) minimum height (lower pressure height loss), but in any case of simple mechanical design.

C) Distribution of the gaseous reagent with negligible pressure head loss in each individual tube depending on the film thickness and thus the flow rate of the liquid reagent, the conversion profiles and the reaction temperature along the tube.

This combination of factors allowed for: excellent results were obtained and no calibration was required when changing the flow and / or type of liquid reagent used.

The process for sulfonating or sulphating organic liquid compounds by treatment with gaseous sulfur trioxide present in a carrier gas is characterized in that the liquid reagent is fed from a common liquid distribution chamber, which is kept completely filled, into a set of equal straight, vertical and parallel tubes through an annular slot in the form of a film, the tubes having a length of 5 to 7 m and an inner diameter of 20-30 mm, the gaseous reagent being fed from a common feed chamber for the gaseous reagent above. for the set of vertical and parallel tubes, above the annular liquid distribution slot, the feed pressure of the gaseous reagent is about 0.01 - 0.05 MPa, preferably 0.02 - 0.04 MPa, this feed pressure being substantially the same as the pressure drop caused by the flow of gaseous reagent inside the individual tubes, which are fed through the reacting liquids, and wherein feed pressure The liquid reagent exceeds the feed pressure of the gaseous reagent, the overpressure at the feed of the liquid reagent relative to the feed pressure of the gaseous reagent being about 5 to 15 cm of liquid column, and the set of vertical and parallel tubes externally by circulating a liquid coolant in a common reactor housing surrounding all the tubes.

The carrier gas consists at least in part of the gas extracted from the collection chamber in the same reactor.

The device, which is suitable for carrying out the method according to the invention and which is of the type comprising a set of vertical tubes, arranged in parallel with respect to each other and fed with the gaseous reagent at their upper end via a conventional distribution chamber, is characterized in that the cross-section of each tube is substantially constant from the cross-section when feeding the gaseous reagent down to the lower end. 447 378 The liquid reagent is fed into each tube near its upper end via a circular slot arranged in the cross section of the tube.

The outside of each tube is cooled by means of a suitable coolant which is allowed to circulate in one or more chambers, which are arranged outside the tubes.

Finally, the device also comprises suitable means for adjusting the size of the opening for the above-mentioned slot.

The invention is described in more detail below with reference to the accompanying drawing, in which: Fig. 1 shows a schematic, vertical cross-section through a suitable embodiment of the reactor according to the invention; Fig. 2 shows the detail denoted by II in Fig. 1 in magnification; Fig. 3 shows a cross-section along the line III-III in Fig. 1: Fig. 4 is a schematic section of three tubes in the reactor, showing a first operating condition of the tubes; Fig. 5 and Fig. 6 are views similar to that of Fig. 4 showing two different operating conditions.

As can be seen from the drawing, reactor 1 is formed by a set of vertical and parallel tubes 10, which are arranged side by side and connected at the top to a feed chamber 70 for the gaseous reagent, which comes via a line 12 from a plant which produces gaseous SO 3, preferably by catalytic conversion.

Furthermore, the tubes 10 are connected at the bottom to a chamber 40 for collecting the reaction products, which are taken out by means of a line 13, shown only schematically.

A coolant, preferably water, circulates inside the cylindrical vessel of the reactor but on the outside of the tubes 10.

When the exothermic reaction between the liquid products to be sulfonated or sulphated, on the one hand, and the gaseous reagent consisting of sulfur trioxide, on the other hand, takes place mainly in the first or upper part of the tubes 10, the coolant suitably has the same flow direction. as the reaction mixture, ie downwards. 447 378 Therefore, the device is provided with at least one upper line _20 for supplying coolant and a lower line 21 for ut- wau = ~ ......, s _..._.._._._._._-. .e. ._ .i ._ in taking the same.

Suitable horizontal or sub-horizontal membranes 22 increase the turbulence of the coolant and its path in a manner known per se. Therefore, the coolant circulates in a space bounded by the outside of the pipes 10, the inside of the lid of reactor 1 and the two tube plates 23 and ZÄ, whereby the tubes 10 are moved tightly.

A third tube plate 25 is arranged above the tube plate 23, so that below the chamber 70 for distributing the gaseous reagent t it delimits a second chamber 15 for distributing the liquid reagent. One or more conduits 16 lead the liquid reagent into the chamber 15. For the further transport of the liquid reagent from the distribution chamber 15 to the individual tubes, there is an input device, shown in detail in Fig. 2, for each tube.

As shown in Fig. 2, each tube 10 comprises an upper part 30, which is cylindrical and has a slightly larger diameter, the upper end of the tube 10 communicating with the lower end of the upper part 30 via a short conical part 31. .

The upper cylindrical part 30 is provided with a suitable number of channels 38 for the liquid reagent and its outside is in a suitable space in contact with the inside of a cylindrical pipe sleeve 33, by means of which the connection to the plates 23 and 25 becomes dense.

The pipe sleeve 33 is provided with channels 36 for the liquid reagent of such size and peripheral distribution that it does not generate pressure head losses when the liquid passes.

Arranged on the inside of the upper part 30 of pipe 10 is a second pipe sleeve 50, the outside of which is in contact with the inside of the upper part 30 with the exception of a middle part, where there is a wide annular groove 51.

The inner wall of the portion 30 and the groove 51 provide an annular space which can receive the liquid reagent coming from the channels 38 and 36 which terminate in the groove 51. 447 378. Suitable axial channels 52, which are shown only schematically in Fig. 2, makes it possible to empty the liquid reagent downwards from the annular space delimited by the groove 51. The pipe sleeve 50 comprises a lower conical end with the same opening angle as the connecting zone 31 between the elements 10 and 30.

Between the lower end of the pipe sleeve 50 and the connecting element ß1 there is therefore an annular gap adjacent to the generators in a truncated cone, the width of which is defined by the vertical position of the pipe sleeve 50.

The pipe sleeve 50 is provided at the top with a threaded upper part 54, which can be screwed onto the upper edge of the upper part 30. In this way it is possible to delimit the cross-section of the annular passage between the lower edge of the pipe sleeve 50 and the conical connecting element 51 by screwing up or down the pipe sleeve 50 on the part 30. The annular passage formed by the generatrices in a cone promotes the distribution of the liquid reagent in the form of a film, denoted by 60 in Fig. 2, along the entire inside of the tube 10.

The inner diameter of the pipe sleeve 50 is suitably the same as the inner diameter of the tube 10, so that the gas coming from the distribution chamber 70 can be made to flow along the free surface of the film 60 without being subjected to any appreciable pressure height losses.

Still, it is clear that due to the uncomplicated constructive design of the liquid reagent distributor, it is very difficult to obtain a truly precise control of the flow rate of the liquid. In fact, during tests without feeding gaseous reagent, a variation of up to as much as 20% was noted between the nominal flow rate and the velocity of the individual tube 10 in the reactor.

Notwithstanding this, as will be explained in more detail below, in the process according to the invention it is possible to keep the deviations of the ratio between the flow rate of the gaseous reagent and the flow rate of the liquid reagent within strict limits. Such a result is very surprising in view of the fact that the most significant difficulty in connection with all reactors operating with films is precisely the correct proportioning of the two reagents.

According to the present invention, the pressure at the inlet of the gaseous reagent is considerably lower than the pressures at the inlet of the gaseous reagent according to known methods. According to the invention, the feed pressure amounts to approximately 0.01 - 0.04 MPa. Depending on the liquid raw materials used, the pressure at the feed of the liquid reagent is higher than the pressure of the gaseous reagent to an extent corresponding to the height of the liquid level prevailing in the distribution chamber of the liquid reagent.

Despite the low feed pressure of the two reagents and the fact that the flow rate of the liquid reagent can vary by up to over 20% from one tube to another, it was surprisingly found that the molar ratio of the liquid reagent to the gaseous reagent remained very close to that. intended average value with very small differences along the tubes, if one looks at the results obtained. A possible explanation for this surprising result is given in connection with the following discussion of Figs. 4, 5 and 6.

Assume that within the time interval (to -tl) the same ideal situation prevails in each of the three tubes 110, 210, 310 with the same diameters and lengths, i.e. the three flow rates of the liquid reagents L1, L2, L3 are equal, the three flow rates of the three gaseous reagents are equal G1, G2, G3 and thus the three molar ratios R1, R2, R3 are corresponding the intended optimal molar ratio is equal, in which case, if the diameters of the three tubes are exactly equal, the reaction will have gone exactly the same length along the three tubes at the same levels, as shown in Fig. 4, where the designations P60, P90, P98 indicate the levels that correspond to a turnover rate of 60%, 90% and 98% respectively.

The length of the tubes is selected so that the contact time between the two reagents can be substantially sufficient under optimal feeding conditions to ensure practically complete conversion of the liquid reagents (conversion rate close to 100%). In this way, it is always ensured that the reaction is completed in each tube, even under conditions other than the optimum, a situation which may arise due to disturbances or the like.

Assume now that for some reason within a time interval t1 - t2 there is a variation in the flow rates of the liquid reagent L1, L2, L3, the three flow rates of the gaseous reagent G1, G2, G3 remaining unchanged, so that for example. L1 = Lt / 3, L2 = 0.9 Lt / B, LB = 1.1 Lt / 3, where Lt denotes the total flow rate of the liquid reagent in the three tubes, which is kept constant. In tube 110, of course, the situation remains unchanged compared to that shown in Fig. U, and the levels P60 and P90 and P98 thus remain unchanged. Due to the lower flow rate of the liquid, an increase of the levels P60, P90, P98 will take place in tube 210, while the opposite result is obtained in tube 310 due to the higher flow rate of the liquid.

It should now be noted that the differences in pressure between chambers 70 and HO are equal to the pressure drop in each of the three tubes, in which therefore the pressure drop is the same.

It should further be noted that together with the change in the degree of turnover, the viscosity and thus the thickness of the film, which consists of a mixture of the liquid reagent and the liquid product from the reaction, changes considerably.

In the progressive progress of the reaction, in particular, there is an increase in the viscosity and thickness of the film, which consists of the mixture of the liquid reagent and the liquid reaction product.

Fig. 5 shows that the height hä for the part of tube 310 where the degree of turnover is higher than 98% is shorter than the corresponding height h1 in tube 110 and that the height h1 is in turn shorter than the height h2. Depending on their different lengths h1, h2, hay, the three tubes thus have different average sections for the passage 447 378 ll of the flow of the gaseous reagent, as the average thickness of the liquid film along the tubes is different.

Since the three flow rates of the gaseous reagent in tubes 110, 210 and 310 are obviously dependent only on the respective average sections of passage, the pressure difference at the end point of the three tubes being the same as above, the following result is obtained: in tube 210 with a average section for passage smaller than the original, shown in Fig. 4, a decrease in the flow rate of the gaseous reagent will occur, which tends to lower the molar ratio of the two reagents down to the original, optimum starting value; in tube 310 with an average section for passage larger than the original, shown in Fig. 4, an increase in the flow rate of the gaseous reagent will occur, which in this case tends to increase the molar ratio to the original, optimum initial value. However, based on torque t1, it would be possible that although the three flow rates L1, L2, L3 of the liquid reagent remain constant and equal, the flow rates of the gaseous reagent vary so as to obtain, see Fig. 6 , e.g. G1 = Gt / 3, G2 = 0.9'Gt / 3, G3 = 1.1 ° Gt / 3, where Gt denotes the total flow rate of the gaseous reagent in the three tubes, which rate is kept constant.

In tube 110, the position obviously remains unchanged compared to Fig. 4 and thus the positions of the levels P60, P90, P98 remain unchanged. Due to the lower flow rate of the gas, tube 210 will exhibit a decrease in levels P60, P90, P98, while tube 310 will exhibit an increase in these levels due to the increased gas velocity. For the same reasons as in the case discussed above, there will be a decrease in the gas flow rate in tube 310 and an increase in the flow rate of the same gaseous reagent in tube 210 as the respective average passages for passage will decrease in tube 310 and increase in tube 210.

Also in this case the molar ratios R2 and R3 will be changed to optimal initial values. In addition to the balancing effect described above due to the modification of the transformation profiles in the tubes, there is also another important balancing effect, which utilizes the significant change in viscosity with temperature. This means that, if the average temperature in the liquid film inside the tubes varies, the average viscosity of the liquid also varies to a corresponding degree. As a result, for the same flow rate, when the average temperature of the film increases, the average thickness of the film decreases and therefore the average passage of the gas will increase. The opposite relationship occurs if the average temperature of the film drops.

Referring to the three tubes shown in Fig. 4 and to the possible different situations shown in Fig. 5, therefore, the total effect of tube 210, which is characterized by a decrease in the flow rate of the liquid reagent, means that a a smaller amount of material is reacted per unit time and therefore a smaller amount of reaction heat is released.

Since the temperature and flow conditions of the refrigerant remain the same, in this situation the average film temperature will be lower than the original, due to less heat of reaction being taken up by the refrigerant. This results in a higher average viscosity, higher average film thickness and as a result lower passage path for the gas.

Since the pressure at the end of the tube 210 is unchanged, the gas flow rate G2 will decrease and therefore the ratio R2 tends to decrease towards the original optimum value. In tube 310 with the conditions shown in Fig. 5, on the other hand, the effect of the increasing flow rate of the liquid reagent will result in an increase in the amount of material reacted per unit time, and consequently in a larger amount of heat of reaction released.

This situation is exactly the reverse in relation to the previous one and the final result will be an increase in the average film temperature, a decrease in the average film viscosity and thereby a longer passage path for the gas. In this case, the flow rate of the gas will increase so that it increases the ratio R3 in the direction of the original optimum value.

In the situation shown in Fig. 6, where the flow rates of the liquid reagent are constant, the average value of the film temperature is practically unaffected and therefore this balancing effect depends only on the variation in conversion profiles.

These two balancing effects are so strong as to compensate for the unbalanced effect due to the variation in flow rate of the reagents and, as shown above, they do not restore the original optimum value for the flow rates in each tube but only the original value. on the molar ratio between the two reagents.

Based on the ideal situation in Fig. 4, when the temporary period has ended and the balancing effects have exerted their influence, in fact the unique situation, which applies to the total material balance of the entire reactor, will be: R1 = R2 = R3 = Rt = - Despite the fact that the flow rates in each tube deviate from the ideal velocities GT / 3 and LT / 3, the molar ratio in each tube is therefore the correct one achieved by external control devices on the reactor.

Below are some examples of embodiments of the method according to the invention.

Example 1 This example shows the operating conditions used for sulfonation according to the invention of linear dodecylbenzene of varying composition and a length of the aliphatic chain between C9 and C15. 447 378 14 - content of sulphonatable material in the raw material 98.5% - average molecular weight of the raw material 267 - flow rate of the raw material 180 kg / h - concentration SO3 in the carrier gas 5 vol% - temperature of SO3 fed into the reactor 36-40 ° C - pressure when the gaseous reagent enters the reactor 140 mm Hg The reactor according to the invention had the following characteristics: - number of tubes 7 - inner diameter of the tubes 25 mm - length of the tubes _ 6000 mm Water with a temperature of 250 C was used as coolant. The temperature of the sulfonic acid at the outlet of the reactor was 4 ° C.

After aging and stabilization, the following values were obtained when analyzing the composition and properties of the product: - amount of unsulfonated material in the reaction product 1.35% - amount of free H 2 SO 4 below 1% 25 ° Klett - color in the product Example 2 This example shows the operating conditions as was used for the sulfation of synthetic lauryl alcohol (C12 - C15). ~ average molecular weight of the raw material 207 - flow rate of the raw material 150 kg / h - concentration SO3 in the carrier gas 5 vol% - temperature of SO3 380 C fed into the reactor - feed pressure for the gaseous reagent 136 mm Hg The reactor used had the same characteristics as in Example 1 exploited.

Water with a temperature of 200 C was used as coolant. The sulphated product had a temperature of 39 ° C when it came out of the reactor.

Analysis of the neutralized product: 4,447,378 - amount of osulfonated material 1.9% - content of Na2SO4 0.88% - color 7 ° Klein - The neutralization was carried out in aqueous solution. The above values for unsulfonated material and sodium sulphate refer to 100% active substance.

Example 3 This example illustrates the operating conditions used in the sulfation of synthetic lauryl alcohol (C12 - Cl5), ethoxylated with three moles of ethylene oxide. - average molecular weight 339 - flow rate of the raw material 130 kg / h - concentration SO3 in the carrier gas 2.5 vol% - temperature for SO3 360 C fed into the reactor - feed pressure for the gaseous reagent 230 mm Hg The reactor used had the same data as in the example pile 1 used. When leaving the reactor, the product had a temperature of 400 C. The cooling water had a temperature of 300 C.

Analysis of the neutralized product: - amount of unsulfonated material 1.3% - content of Na2SO4 1,4% ~ color 15 ° Klett The neutralization was carried out immediately after the sulphation in aqueous solution. The above values for unsulfonated product and sodium sulfate are based on 100% active substance. It should be noted that in the three examples above, the molar ratio of the two reagents (SO 3 and liquid raw material) was kept at the value (1.03 - 1.06): 1.

Furthermore, the color of the final product was determined on a 5% solution using a Klett-Summerson color meter with a No. 42 blue filter. A 40 mm cell was used. The color was determined on the product in the form in which the product left the reactor without being subjected to any bleaching process. 447 378 16 .The invention-is of course not limited to those above. reported examples, but is intended to cover all modified and equivalent procedures that fall within the scope of the appended claims.

Claims (5)

447 378 17 Patent claims 1. l. Process for sulfonation or sulphation of organic. liquid compounds by treatment with contained in a salvage gas. gaseous sulfur trioxide, characterized in that the liquid reagent is fed from a common liquid distribution chamber (15). which is kept completely filled. into a set equal in size. vertical and parallel tubes (10) through an annular slot (55) in the form of a film (60). the tubes having a length of 5 to 7 m and an inner diameter of 20-30 mm. the gaseous reagent is fed from a common feed chamber (70) for the gaseous reagent above the set of vertical and parallel tubes (10). above the annular liquid distribution slot (55), the inlet pressure of the gaseous reagent is about 0.01-0.05 MPa. wherein this feed pressure is substantially the same as the pressure drop loss caused by the flow of gaseous reagent inside the individual tubes. which are permeated by the reacting liquids. and wherein the inlet pressure of the liquid reagent exceeds the inlet pressure of the gaseous reagent. wherein the overpressure at the feed of the liquid reagent relative to the feed pressure of the gaseous reagent amounts to about 5 to 15 cm of liquid column, and wherein the set of vertical and parallel tubes (10) is cooled externally by circulating a liquid cooling medium in a common reactor shell. (l) which surrounds all tubes 615118. The device for carrying out the method according to claim 1, comprising a set of vertical tubes (10), arranged in parallel with each other and fed with the gaseous reagent at their upper end via a conventional distribution chamber (70). characterized in that each tube (lo) section is substantially constant from the feed section of the gaseous reagent down to the lower end. 447 578 18. Device according to claim 2, characterized in that the liquid reagent is fed into each tube (10) near its upper end through a annular slot (55) in a cross section of the tube. Device according to claim 3, characterized in that the outside of each tube (10) is cooled by means of a suitable coolant. circulating inside one or more chambers. which are arranged outside the tubes. Device according to Claim 3. KNOWN that it is provided with suitable means for adjusting the degree of opening of the slot (55).