HRP920929A2 - Peroxoacid manufacture - Google Patents

Description

The field of technology

This invention relates to the production of peroxo acids, and more specifically to the process and apparatus for the production of peroxomonosulphuric acid.

Technical problem

Peroxomonosulfuric acid, sometimes referred to herein as Karo acid, has the formula H2SO5. It is a strong oxidizing agent that can be used in a wide range of industries, including for example in metal extraction and process industries in chemical synthesis and for the rapid and efficient detoxification of effluents containing, among others, phenolic, cyano, sulfur and other organic and inorganic species capable of oxidation.

The scale of its use is narrowed by the difficulties and cost of its production, transportation and storage, which in practice means and for the sake of convenience that it is usually obtained at the same location as the intended place of its use. It is also recommended that it be used quickly after its manufacture.

State of the art

There are two bases of the proposed procedure for obtaining Karo acid. One process requires partial hydrolysis at elevated temperature of peroxodisulfuric acid H2S2O8 in an acidic solution obtained by electrolysis or acidification of an alkali metal salt or ammonium perdisulfate salt. This method is suitable for trial scale extraction, but is of little use for larger volume extraction. The second way involves the reaction between an aqueous solution of hydrogen peroxide and sulfuric acid, oleum or gaseous SO3. For sulfuric acid, the equation includes:

H2O2 + H2SO4 = H2O + H2SO5

The second way is more suitable because starting materials are used that are more commercially available. Special importance is attached to reaction control. Thus, for example, in GB-A-844 096, page 2, lines 28 to 42, E I Du Pont specifies a reaction temperature of up to 25ºC, such as 0 to 15ºC, and explains that temperatures above 25ºC are not recommended. because they lead to poor efficiency, due to the hydrolysis of monopersulfuric acid and losses of active oxygen. The next paragraph shows that the oleum is added at a controlled rate to the hydrogen peroxide, while maintaining stirring and cooling the mixture. As a consequence of this, the reaction vessel is complicated and expensive to construct and operate, and in addition the production rate is greatly reduced by cooling.

In GB-A-738,407 and the corresponding USP-2,789,954 published in 1957 and owned by Stevenson (Dyers) Limited, column 1 lines 42 to 49, a process is described in which controlled amounts of hydrogen peroxide and concentrated sulfuric acid are mixed under such conditions as to give a mixture containing persulphuric acid, the mixture is cooled to prevent any further reaction and then diluted generally immediately with water. The patentees advocate that the flow be regulated so that the temperature of the mixture reaches at least about 50ºC and that it is cooled immediately after this for example by mixing the reactant at the inlet of the cooled condenser or in fact within the cooling zone of the water jacketed condenser. It is clear to the reader that rapid and forced cooling are the basic element of their procedure, both in concept and in practice. In addition, the overall process observed in the patent is cumbersome and in practice requires double cooling.

More recently, Air Liquide in US P 3,900,555 and US P 3,939,072, which were filed in 1975/76, pointed out that there is a need for a reactor capable of producing monoperoxysulphuric acid at the time it is required for use and described as an example for this purpose a reactor double-lined constant level with an overflow to separate the product from the generator and two symmetrically placed reagent inlets. Cooling water circulates through the lining. In the apparatus exemplified, the maximum hourly rate of permonosulfuric acid solution production was only 10 times the liquid volume in the reactor, probably limited by the capacity of the cooling jacket to prevent the reaction temperature from exceeding the top side. Of course, moving from the laboratory-sized apparatus provided by Air Liquide to commercial-sized, albeit theoretical possibilities, can be expected to further reduce the production rate due to the fact that the surface-to-volume ratio (and thus the cooling rate) changes inversely with the radius of the sphere or cylinder or it is required to introduce compensatory complications in the apparatus. Therefore, the Air Liquide apparatus is relatively complex and due to the fact that it has a relatively small production capacity, the consequence is that it is relatively expensive and that it is expensive to exploit.

The inventors of this invention realized that the exploitation of Karo acid for various oxidations is prevented by the price and the cost of exploitation of conventional devices for its production.

Additionally, many of the sites where Karo acid would be potentially useful are located in remote locations. For other potential applications, Karo acid is intended to modify chemical or hydrometallurgical processes or the treatment of waste produced in such processes, so the apparatus installed for obtaining Karo acid should be located next to the existing plant. In both situations, the size of the apparatus that provides a given volume of oxidant is of practical importance.

Description of the solution

Therefore, a program has been set up that should provide a process that is more cost-effective and that will provide equipment that should be relatively suitable for transport and use in many locations and relatively simple and robust.

The inventors of the present invention also realized that in any process and apparatus, consideration must be given to the fact that the reaction to produce permonosulfuric acid is exothermic, and that if the reagents are introduced into the product reservoir, the heat produced can be distributed throughout the reservoir, so that the increase in temperature of the reaction mixture resulting from the introduction of a unit amount of reagent is proportionally reduced. Therefore, any reduction in the size of the reservoir will accelerate the potential increase in temperature of the resulting mixture, which will therefore also increase the probability of decomposition of hydrogen peroxide, since the rate of this last reaction depends on temperature, but will significantly increase the risk of self-accelerating decomposition that occurs because the decomposition reaction peroxide itself is very exothermic. This is not only a waste of reagents, but the resulting forced ejection of a very warm solution of Karo acid, for example in the form of a spray, will be particularly dangerous for anyone nearby. Therefore, based on normal safety considerations, they were aware of a reasonable and well-founded bias in favor of apparatus with the importance of cooling and control of the reaction mixture, as described in the Air Liquide Contact Volume Generator and Control, and also of an opinion against apparatus having such permeability. to compromise cooling control.

According to one aspect of the present invention there is provided a continuous process for the production of peroxomonosulfuric acid by the reaction between concentrated sulfuric acid and concentrated hydrogen peroxide indicated by introducing the two reagents under pressure into a closed tubular reaction chamber having an inlet for a sulfuric acid solution at or adjacent one end, and an outlet for the reaction mixture at the end remote from the sulfuric acid inlet and the hydrogen peroxide solution inlet, which is placed in the middle between the sulfuric acid inlet and the reaction mixture outlet, thereby introducing the hydrogen peroxide solution into the flow of the sulfuric acid solution, whereby the reaction chamber so dimensioned in relation to reagent flow rates that the flow rate per minute is at least about 20 times its internal volume, measured between the hydrogen peroxide solution inlet and outlet.

According to another and related aspect of the present invention there is also provided apparatus suitable for the production of peroxomonosulfuric acid by the reaction between concentrated sulfuric acid and concentrated hydrogen peroxide which is indicated by a closed tubular reaction chamber having an inlet for the sulfuric acid solution at or adjacent one end, and an outlet for the reaction mixture at the end far from the sulfuric acid inlet and an inlet suitable for the hydrogen peroxide solution, which is placed in the middle between the sulfuric acid inlet and the outlet for the reaction mixture, whereby the hydrogen peroxide solution is fed into the flow of the sulfuric acid solution during operation, at for which the reaction chamber is so dimensioned in relation to the flow rate of the reagent that the flow per minute is at least about 20 times its internal volume measured between the inlet for the hydrogen peroxide solution and the outlet.

It is clear that the apparatus used in the process of the invention does not employ any cooling devices around the reaction chamber, with the result that the reaction occurs adiabatically, the temperature of the reaction mixture is substantially higher than room temperature and reaches an equilibrium point which remains reasonably constant as the reagents are charged into chamber, but the actual temperature level is determined first by the sulfuric acid and hydrogen peroxide reagent mixtures and their relative rates of introduction. The equilibrium temperature obtained inside the chamber seems to change depending on the concentration of peroxomonosulfuric acid obtained in the product and to have a tendency to increase with the increase in the total concentration of both reagents, and as their molar ratio approaches 1:1.

One of the important characteristics of the apparatus and process according to the invention is the order in which these two reagents are introduced into the reaction chamber. It has been found that there is a significant difference in effect if the reagents are introduced in reverse order. When an aqueous solution of hydrogen peroxide is introduced into the flow of sulfuric acid according to the invention, an equilibrium mixture of Karo acid is formed very quickly. On the other hand, in tests of the reverse procedure, every time the same concentrated sulfuric acid is introduced into the flow of the same aqueous solution of hydrogen peroxide, which flows in the same apparatus and under otherwise identical operating conditions, the result was initially and constantly unacceptable. The temperature of the reaction mixture rose in the course of a few seconds after the previously determined equilibrium temperature up to which partial evaporation was observed. Pressure builds up in the reaction chamber and steam is forced out of the reactor. The test was brought to a stop as quickly as possible by stopping the influence of the reagent.

It was found from the tests that not only is there a significant difference between the two modes of operation when using a closed adiabatic reaction chamber according to the present invention, but also that the feasible mode of operation according to the present invention is the opposite of the preferred mode of operation described by Du Point in GB -A-844096.

It is understood that this invention uses apparatus in which the reaction chamber is closed, i.e. it is not vented to the atmosphere. This means that the only outlet for the reaction mixture is through the exit port and as a consequence of this it is of practical importance to control the rate of entry of the reagents in the ratio identified above, so as to prevent, or at least keep within reasonable limits, the increased decomposition of peroxygen which will occur if the flow is allowed to fall below the minimum limit.

In a further aspect of the present invention, the apparatus for the controlled preparation of the Karo acid solution comprises a tubular reaction chamber having an inlet for a sulfuric acid solution at or adjacent to one end, an outlet for the reaction mixture at an end remote from the inlet, and in a transverse direction an inlet for a hydrogen peroxide solution which is placed in the middle between the sulfuric acid inlet and the outlet, wherein said reaction chamber includes an annular area that extends longitudinally adjacent to the hydrogen peroxide inlet of the reagent, wherein in operation the hydrogen peroxide solution inlet is introduced through its inlet directly transverse to the flowing sulfuric acid solution longitudinally through the ring area towards the outlet of the reaction mixture.

In one particularly suitable design of the reaction chamber, the width of the annular region, which here means the difference between the inner and outer diameters of the circles defining the region, is increased at or just before the entry of the hydrogen peroxide. The increase can be gradual or gradual. In some particularly suitable embodiments, the increase in width of the region is such that the linear velocity of liquid flow within the annular region of the reaction chamber toward the outlet is similar only for sulfuric acid flow and for sulfuric acid/hydrogen peroxide mixture flow.

In practice, the annular region near the sulfuric acid inlet is primarily narrow, i.e. the ratio of the former to the latter is primarily between 0.75 to 1 to about 0.9:1. As a consequence of this, the sulfuric acid solution flows through the annular region at a relatively high speed towards the outlet. This helps to mix the sulfuric acid solution with the hydrogen peroxide solution when it is fed gradually into the reaction chamber. Near the hydrogen peroxide inlet and extending toward the outlet, the width of the annular region is suitably selected from an inner to outer diameter ratio of about 0.5:1 to about 0.8:1. The reaction chamber is primarily cylindrical or frustoconical near the outlet.

Preferably, the reaction chamber has an overall length measured from the sulfuric acid inlet to the outlet that is substantially greater than its transverse diameter, such as in the range of at least 3:1, and suitably from about 4:1 to about 10:1.

An annular chamber can be obtained in an elegant and robust manner by introducing suitably shaped and sized cores coaxially with the cylindrical reaction vessel. By reducing the diameter of the core as it approaches the exit end, the cross-section of the annulus increases. The core can have longitudinal or spiral ribs that extend partially into the annular space. In order to simplify the construction of the apparatus, increase its robustness and minimize the risk of leakage from the reaction chamber on the assemblies, the use of a stationary core is very appropriate. Alternatively, although not necessary, the core may be rotatable about a longitudinal axis. If a rotating core is used, it is particularly desirable that the width of the annular region be extremely narrow in the region between the sulfuric acid inlet and its adjacent end, so as to minimize any interaction between the sulfuric acid and the junction between the core and the outer wall of the chamber.

It is clear that a similar stepped annular region can be achieved by varying the diameter of the bore defining the outer wall of the annular region together with a core of constant diameter, or a further option, the diameters of both the core and the cavity can be varied.

Reagent flows through the inlet are preferably impingement-free and are often directed transversely into the reaction chamber, i.e. essentially at right angles to the longitudinal axis of the reaction chamber. Each inlet can be elevated slightly above the volume of the reaction chamber or at an angle slightly relative to the actual geometric radial direction so as to direct the flow into the annular chamber. The two inlets may be positioned at a relative angle to each other, when viewed along the longitudinal axis of the chamber, but in particularly suitable embodiments the inlets are positioned opposite.

In some annular embodiments, it is desirable to angle the hydrogen peroxide inlet backward, i.e. away from the outlet, for example so that the contact angle with the sulfuric acid stream is represented and preferably in the range of at least about 90º to about 165º, and is suitable in the range from about 95º to 125º. Further suitable contact angles are around 135º and 150º. Thus, by angling the entrance to the hydrogen peroxide solution, the two solutions are somewhat opposite, before one solution meets the other transversely, and it is believed that this way helps the mixing of the solutions and prevents "dead spots" which could cause decomposition of the peroxy species present.

The outlet opening primarily has a cross-sectional area smaller than the area of the adjacent reaction vessel, so that a back pressure is formed. This regulates the rate of liquid flow from the chambers together with the pressure on the pumped reagents and therefore the flow rate. It is preferable that it contains a non-return valve.

A reaction chamber usually primarily has inlets more than outlets. In practical and convenient embodiments, the mounting is often approximately vertical. It is most suitable to mount the reaction chamber approximately vertically and/or directly above the liquid level in the vessel in which the Karo acid is to be used, so that the reaction mixture can flow directly from the chamber to the treatment area.

The rate of flow of reagents into the reactor is primarily controlled along with the volume of the reactor and the size of its outlet so that the temperature of the mixture is able to maintain temperature equilibrium while still in the reactor. The maximum flow rates will depend on the composition of the reagents and the molar ratio at which they are used and, accordingly, the equilibrium temperature reached in them. In many cases, the maximum product flow rate per minute falls within the range of approximately 40 to 80 reactor volumes.

By adopting the apparatus according to this invention, it is possible to safely produce a large volume of Karo acid, without the use of a large generator. For example, a reaction chamber of only 20 ml of total volume, but with a flow rate of 30 volumes per minute, can produce almost 1.3 t of product per day if operated constantly, and at 80 volumes per minute, about 3.5 t of product per day can be obtained. Similarly, a chamber having the volume of a cup of coffee, i.e. about 250 ml, can produce about 16 t to 40 t of product per day if operated with the same residence time resulting from 30 to 80 flow volumes per day. The ratio of H2SO5 in the product depends, as might be expected, on the concentration of sulfuric acid and hydrogen peroxide reagent used, and on their relative molar ratio. It is clear that the apparatus of such dimensions can be easily transported and set up easily, even in very narrow working areas. It is also clear that the reactor can be controlled to give product within wide limits of requirements. Where an even wider area is required, it is possible to use two or more reactors in parallel with suitable controls to regulate the reagent flows to one or more reactors as required at any given time.

The adiabatic generator is preferably constructed of materials resistant to attack by reagents and products. In particular, certain fluorocarbon polymers such as PTFE, FEP and PFA are suitable, as they combine the qualities of robustness with chemical resistance. Other materials worth considering contain tantalum.

Relatively large flows in this invention are not only advantages, but it is a basic characteristic during operation according to the process of the invention. If the flow rates are to be significantly reduced, the residence time in the reaction chamber should be increased accordingly, and the result will not be a simple reduction of the product obtained, but instead the essential safety of the process will be uncertain and/or the amount of peroxygen product will be significantly reduced. This is because the reaction mixture will be left inside the confined reaction chamber for an extended period at the elevated temperatures obtained when concentrated sulfuric acid is allowed to react adiabatically with hydrogen peroxide. By controlling the flow in the limited reaction chamber, it is possible to achieve a balance of the concentration of permonosulfuric acid in the reaction mixture without high decomposition of the remaining hydrogen peroxide, thus without simultaneously creating pressure from gas production.

The process according to the invention is favorable for the reaction between concentrated sulfuric acid and hydrogen peroxide in which the molar ratio of sulfuric acid to hydrogen peroxide is specially selected in the ratio of 0.5:1 to 5:1 and is particularly favorable when the molar ratio is within the limits of 1:1 up to 3:1. The concentration of sulfuric acid is normally at least 90% w/w and often from 92 to 99% w/w. The concentration of hydrogen peroxide used is normally at least 50% and especially up to 60% to 75% w/w. In a number of very useful cases, the total amount of water introduced into the two reagents represents 25 to 40 mol % relative to the total moles of water plus hydrogen peroxide plus sulfuric acid.

The temperature reached inside the reaction chamber in many cases exceeds 80ºC, but primarily the reactants are chosen so that the effluent temperature of the product does not exceed 100ºC. Such a temperature range represents the one in which the method according to the invention will be used most efficiently. It is preferable to record the temperature, for example in order to regulate the introduction of reagents that are held back if the temperature of the reaction progress is too high.

Only to a certain extent, the temperature reached at a given molar ratio of sulfuric acid:hydrogen peroxide can be varied by changing the opposite amount of water used, for example by changing the concentration of the hydrogen peroxide batch. It is particularly advantageous to select and control the batch of reagents to the reactor so that the mixture reaches a temperature of about 85° to about 105°C.

The solution of Karo acid obtained according to this invention is convenient for immediate use. The size of the reactor relative to the production rate means that the response to oxidant demand can be extremely fast.

Where the requirement is lower than the minimum flow rate for safe reactor operation, then intermittent operation may be employed, but alternatively or additionally, to at least one extent, the volume of the reaction chamber may be reduced by using a larger core, along with the same or similar residence time.

In one particularly suitable embodiment, the product is allowed to flow directly, for example under the influence of gravity, into the reservoir of another vessel in which it is desired to use it without passing through cooling devices. The high product flow rate and the proximity of the adiabatic reactor to the treatment reactor means that the delay between its production and its introduction into the treatment reactor is normally very short. Alternatively, and in a further set of advantageous embodiments, the product may be allowed to flow through a conduit placed in the treatment reactor and covered with liquid therein so that the product is cooled by heat exchange through the walls and conduit.

If desired, the Karo acid product obtained in the generator of the present invention may be passed through a cooling device installed if, for example, it is desirable to store the product rather than use it immediately and under such conditions it is advantageous to achieve sufficient cooling to the temperature of the product was reduced to below about 60ºC to improve its stability during storage. It is understood that if the temperature in the adiabatic generator is reached at about 90ºC, then less than half of the heat needs to be removed compared to maintaining a steady state temperature in the reactor vessel of about 30ºC or lower. Second, the temperature difference is usually about 60-70ºC on average between the product from the adiabatic generator and the generator according to the invention with cooling water, while the temperature difference between the steady state vessel at 30ºC and the same cooling water is 15 to 25ºC, i.e. less than half . This means that the size of any heat exchanger should be only a fraction, eg 1/4 to 1/5, of that required for the same flow rate using the steady state process to produce Karo acid.

The Karo acid product obtained by the process according to the invention can be used for many of the uses described for the product obtained by other processes. Therefore, it can be used to treat wastewater containing oxidizable impurities, or in the extraction or treatment of metals or in purification or in chemical syntheses.

Since this invention has been described in a general way, one of its realizations will be described in more detail, in the form of an example only with reference to a figure showing a longitudinal section of the apparatus.

The apparatus includes a hollow PTFE cylinder 1 with an inner diameter of 20 mm and a length of 150 mm, which is closed at one end by a cup 2 and at its other end with a non-return valve 2 that acts as an outlet. Staged PTFE core 4, located coaxially within cylinder 1 and cup 2, first stage 28 mm long having a diameter of 19 mm, second stage 48 mm long having a diameter of 16 mm and third stage 64 mm long having a diameter of 12 mm . The core 4 is defined by the core defined by the inner surface of the cylinder 1 by a staged circular reaction chamber 5 that ends in a short cylindrical chamber 6 near the check valve 3. The cylinder 1 has an upper introduction opening 7 for sulfuric acid which is placed radially and perpendicularly to the second stage of the core 4 and the lower inlet 8 for hydrogen peroxide, which is placed radially but backwards at an angle of 60ºC to the longitudinal axis towards the third stage of the core 4.

During operation, sulfuric acid is drawn into the circular chamber 5 and forms a current that flows towards the check valve 3. Hydrogen peroxide is simultaneously drawn into the circular chamber 5 and meets the sulfuric acid stream essentially at an angle of about 130º. The two liquids continue to mix together in chamber 6 and the mixture flows out through valve 3.

Example 1

In this example, solutions of concentrated acid (98% w/w) and hydrogen peroxide (70 w/w) are pumped into the apparatus described earlier with reference to the figure, at flow rates of 260 ml/min and 56 ml/min, respectively, provided that is the molar ratio H2SO4 : H2O2 equal to 3.224. The mixture reached a temperature of 86ºC and contained 28.56% w/w peroxomonosulfuric acid (H2SO5 and 0.73% w/w H2O2.

Example 2

In this example, example 1 was repeated, except that the flow rates of sulfuric acid and hydrogen peroxide were 360 ml/min and 43.8 ml/min, respectively, provided that the molar ratio of H 2 SO 4 : H 2 O 2 was equal to 5,715. The mixture reached a temperature of 63ºC and contained 16.9% w/w peroxomonosulfuric acid (H2SO5) and 0.24% w/w H2O2.

Example 3

In this example, example 1 was repeated, except that the flow rates of sulfuric acid and hydrogen peroxide were 210 ml/min and 148.8 ml/min, respectively, provided that the molar ratio of H 2 SO 4 : H 2 O 2 was equal to 0.980. The mixture reached a temperature of 104ºC and contained 39.4% w/w peroxomonosulfuric acid (H2SO5) and 10.3% w/w H2O2.

Example 4

In this example, example 1 was repeated, except that the sulfuric acid and hydrogen peroxide flow rates were 20 ml/min and 92.8 ml/min, respectively, provided that the molar ratio of H2SO4:H2O2 was equal to 1.647. The mixture reached a temperature of 108ºC and contained 43.05% w/w peroxomonosulfuric acid (H2SO5) and 4.5% w/w H2O2.

Claims (19)

1. Apparatus suitable for the production of peroxomonosulfuric acid by the reaction between concentrated sulfuric acid and concentrated hydrogen peroxide, characterized in that it has a closed tubular reaction chamber having an inlet for a sulfuric acid solution at or adjacent one end and an outlet for the reaction mixture at a remote end from the inlet for sulfuric acid and the inlet suitable for the hydrogen peroxide solution, which is placed in the middle between the inlet for sulfuric acid and the outlet for the reaction mixture, whereby the hydrogen peroxide solution is introduced into the flow of the sulfuric acid solution during operation, and the said reaction chamber is thus ^ dimensioned in relation to reagent flow rates that the total flow per minute is at least about 20 times its internal volume measured between the hydrogen peroxide solution inlet and outlet. 2. Apparatus for continuously obtaining a solution of Karo acid, indicated by the fact that it contains a tubular reaction chamber having an inlet for a sulfuric acid solution at or adjacent one end, an outlet for the reaction mixture at an end remote from the inlet and a transversally directed inlet for a hydrogen peroxide solution which is placed between the inlet for sulfuric acid and the outlet, wherein the reaction chamber includes a circular area that exits longitudinally near the hydrogen peroxide for the reagent, wherein during operation the hydrogen peroxide solution is introduced through its inlet and is directly transverse to the solution towards the solution of the sulfuric acid acid flowing longitudinally through the circular area towards the outlet for the reaction mixture. 3. Apparatus according to claim 1, characterized by the fact that the reaction chamber includes a circular area that extends longitudinally near the hydrogen peroxide inlet, where in operation the hydrogen peroxide solution is introduced through its inlet and is directly transverse to the sulfuric acid solution that flows longitudinally through circular area towards the outlet of the reaction mixture. 4. Apparatus according to any one of the preceding claims, characterized in that the reaction chamber contains a circular area near the reagent inlet and a cylindrical area near the outlet. 5. Apparatus according to any of the preceding claims, characterized in that the reaction chamber contains a circular area having a relatively small width near the sulfuric acid inlet and a relatively larger width near the hydrogen peroxide inlet. 6. Apparatus according to any one of claims 2 to 5, characterized in that the circular region of the reaction chamber is formed by inserting a core inside the cylindrical chamber. 7. Apparatus according to claim 6, characterized in that the core is stationary. 8. Apparatus according to any one of the preceding claims, characterized in that the hydrogen peroxide inlet is inclined backwards into the sulfuric acid stream flowing towards the outlet. 9. Apparatus according to claim 8, characterized in that the meeting angle between the hydrogen peroxide and the stream of sulfuric acid is between 95 and 165°. 10. Apparatus for the production of peroxomonosulfuric acid, characterized in that it is essentially as described herein with reference to FIG. 11. A continuous process for the production of peroxomonosulfuric acid by the reaction between concentrated sulfuric acid and concentrated hydrogen peroxide, indicated by the fact that two reagents are introduced under pressure into a closed cylindrical chamber having an inlet for a sulfuric acid solution at or adjacent one end, an outlet for the reaction mixture at at the end far from the inlet for sulfuric acid and the inlet for the hydrogen peroxide solution located in the middle between the inlet for sulfuric acid and the outlet for the reaction mixture, whereby the hydrogen peroxide solution is introduced into the flow of the sulfuric acid solution, and the specified reaction chamber is dimensioned in relation to reagent flow rate such that the flow per minute is at least about 20 times its internal volume as measured between the hydrogen peroxide solution inlet and outlet. 12. The method according to claim 11, characterized in that the characteristic feature of any of claims 2 or 3 to 10 is used. 13. The method according to claim 11 or 12, characterized in that the flow is about 40 to 80 times its internal volume per minute. 14. The method according to any one of claims 11 to 13, characterized in that the molar ratio of sulfuric acid to hydrogen peroxide is chosen in the range from 0.5:1 to 5:1. 15. The method according to any one of claims 11 to 14, characterized in that the concentration of the sulfuric acid solution is from 92 to 99% wt/wt and the concentration of the hydrogen peroxide solution is from 60 to 75% wt/wt. 16. The method according to any one of claims 11 to 15, characterized in that the total amount of introduced water in the two reagents is from 25 to 40 moles. 17. A process for obtaining peroxomonosulfuric acid, characterized in that it is essentially as defined with respect to any Example. 18. Permonosulfuric acid solution, characterized by the fact that it was obtained in the apparatus according to any of claims 1 to 10 or by the process according to any of claims 11 to 17. 19. Apparatus or process for obtaining a peroxy acid solution by reaction between a concentrated precursor acid solution and concentrated hydrogen peroxide using any novel feature or any novel combination of features substantially as described herein.