AU2015412464B2

AU2015412464B2 - A process for the manufacture of sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfonated compounds

Info

Publication number: AU2015412464B2
Application number: AU2015412464A
Authority: AU
Inventors: Navin G. Ashar; Pranav Ashar
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-10-20
Filing date: 2015-12-08
Publication date: 2021-05-20
Anticipated expiration: 2035-12-08
Also published as: WO2017068403A1; AU2015412464A1

Abstract

The invention discloses a process for the manufacture of SO

Description

A Process For The Manufacture Of Sulfur Dioxide, Sulfur Trioxide, Sulfuric Acid, And Sulfonated Compounds

Field of Invention:

The invention relates to the manufacture of Sulfur Dioxide, Sulfur Trioxide, Sulfuric Acid, and Sulfonated compounds like, and not limited to, Methane Sulfonic Acid (MSA), Para Toluene Sulfonic Acid (PTSA), Sulfamic Acid. The invention particularly relates to a process for the manufacture of S0₃ using a 'Cold Process' utilising unique properties of liquid SO? and liquid SO₃, which leads to a higher quality and economic efficiency in the production of SO₃ than conventional processes, which further leads to higher quality and efficiency in the manufacture of the aforementioned derivative compounds. The invention is directed to reduced capital investment and utility cost, less plant area/size, and zero emission of sulfur dioxide.

Background:

The production of Sulfur Dioxide (S0₂) is a basic intermediate step in the manufacture of high-grade Sulfur Trioxide (SO₃) and Sulfuric Acid (H₂S0₄). It is also an intermediate step in the manufacture of sulfonated compounds like, and not limited to, Methane Sulfonic Acid (MSA), Para Toluene Sulfonic Acid (PTSA), Sulfamic Acid. The conventional method for the production of S0₂ is based on burning Sulfur in a high-temperature furnace based on the reaction S + C½ -> SO?. This reaction is highly exothermic and must be performed in a furnace able to withstand very high temperatures. A higher-temperature in the furnace due to a higher concentration of

50₂ in the outlet-gas mix requires costly high-alumina brick lining and repeated maintenance costs.

The SO?, produced in this manner is then fed to a Converter that converts S0₂ to

503 with the aid of a catalyst. The SO₃ is further purified to obtain SO₃ as an end- product, or is used in the manufacture of H₂SO , or is used for sulfonation to produce the aforementioned sulfonation compounds. Typically, the sulfur burning furnace is operated at 1050-1100°C. At this temperature, only 9.5-11% concentration by volume of S0₂ in the output-gas mixture is achieved. There are multiple downsides to this:

1 . The low concentration of S0₂ leads to lower production of SO₃.

2. The SO₂ output from the furnace is at about 1 100°C and must be cooled to a temperature appropriate for the catalyst in the SO₃ converter. Vanadium Pentoxide is a commonly used catalyst that requires cooling to about 410- 430°C. The need to cool the gas mixture by almost 700°C requires an elaborate arrangement requiring additional capital expenditure and operating costs. Also, the high incoming temperature precludes the use of a Cesium- activated catalyst that is more effective than the conventional Vanadium Pentoxide catalyst, but requires a lower operating temperature of 360-380^uC. 3. The high operating temperature of the furnace reduces the furnace's lifetime causing faster depreciation in the furnace's economic value and additional capital expenditures to replace the furnace frequently. In fact, higher concentrations of S0₂ using this process can only be obtained by allowing the furnace to operate at higher temperatures since the reaction of Sulfur and Oxygen is highly exothermic. Higher than 1100°C temperatures in the furnace are practically impossible, which precludes being able to obtain higher SO? concentrations using this process.

Objects of the invention:

Accordingly, the present invention has the following objectives:

To provide a high concentration of SO₂ leading to higher level of concentration in the production of S0₃.

To produce S0₂ at lower temperatures than conventional processes.

To provide a process of manufacture of S0₂ that will increase a furnace's lifetime.

To apply the SO₃ produced at higher concentrations as above in the economically and environmentally efficient manufacture of H₂S0₄ and the aforementioned sulfonation compounds. List of Figures:

Figure 1 shows a block diagram for a typical conventional plant for manufacture of H2SO4 acid/oleum/SOj

Figure 2 shows a flow diagram for part C of the process of invention as applied to existing plants for manufacturing S0₃ and H₂S0₄

Figure 3 shows a block diagram for parts A and B of the process of invention as applied to existing plants for manufacturing SO₃ and H₂S0₄

Figure 4 shows a block diagram for the process of invention as applied to new plants for manufacturing S0₃ and H₂S0₄

Summary of the invention:

The invention proposes a method or a process to produce SO₂ by passing S0₃ through liquid sulfur. The S0₂ thus produced is then used as the sole source of SO₂ for downstream processes. Alternatively, the SO₂ thus produced is used to augment the S0₂ produced using conventional processes of S0₂ manufacture.

The invention is applicable to a number of conventional processes for the manufacture of H₂S0₄ and liquid SO₃ in particular as well as the aforementioned sulfonation compounds. Description of the invention:

The invention discloses a process to manufacture SO₃ and H₂S0₄using SO₂, wherein the S0₂ is manufactured in an innovative manner, as applied to existing plants for manufacturing SO₃ and H₂S0₄ as well as new plants. Additional embodiments of the present invention disclose methods using SC½ that is manufactured in an innovative manner to manufacture the aforementioned sulfonation compounds.

SO₂, according to the present invention, is generated by passing SO₃ through liquid Sulfur (S + 2S0₃ -> 3S0₂ - ΔΗ). This reaction is referred to as the "New Reaction" in the remainder of the present disclosure. The S0₂ produced by means of the New Reaction is used as the sole source of S0₂ or as an augmentation of the conventional steps of S0₂ production outlined above. The new reaction is only mildly exothermic (in other words, generates less heat) compared to the burning of Sulfur. For the purpose of this disclosure, this component is called the "Cold SO₂ Generator" or CSG. The S0₂ so generated is used in the process of manufacturing SO₃ or Sulfuric acid or the aforementioned sulfonation compounds. The New Reaction produces the S0₂ at a lower temperature and at a higher concentration and pressure as described herein.

Augmentation of basic SO₂ production and usage:

The liquid sulfur in the New Reaction is nominally maintained at 140°C, which is also about the temperature at which S0₂ is generated in the aforementioned CSG. In the augmented process (Figures 2 and 3), the generated S0₂ is used in the following manner: t is mixed with the S0₂ from the furnace to increase the S0₂ concentration that is input to the SO₃ converter (the next stage). It is possible to increase the concentration to 20-25%, which is ideal for the catalyst in the SO₃ converter unit.

Since the S0₂ generated in this manner is at about 140°C, its mixture with the SO₂ from the furnace is used to cool the gas mixture. It is feasible to cool the gas mixture that is at a temperature in the range of about 950 °C to 1100 °C when coming out of the furnace to about 600-800 °C by mixing it with the SO₂ from the aforementioned CSG. The lower S0₂ mixture temperature is beneficial because it requires a less elaborate cooling system, and importantly, allows a Cesium-activated Vanadium Pentoxide catalyst to be used in the S0₃ converter. As pointed out earlier, the Cesium-activated Vanadium Pentoxide catalyst lowers the operating temperature requirement to about 360-380°C as against the typical Potassium-activated Vanadium Pentoxide catalyst that requires a temperature of 410-430°C. The Cesium-activated Vanadium Pentoxide catalyst is desirable since it improves the efficiency of the S0₃ converter. Using this process, higher steam generation is achieved than the existing Double Contact Double Absorption (DCDA) processes. In effect, the combination of the higher SO? concentration and the use of the Cesium activated catalyst enabled by the CSG unit enhances the overall efficiency of the Sulfur-to-S0₃ subsystem. A significant benefit of this scheme is that it can be retrofitted into an existing chemical plant for the manufacture of SO₃ and H₂SO₄. The CSG unit is envisaged as an add-on into the existing system and the S0₃ converter catalyst can be reloaded for the new parameters. In effect, the efficiency of an existing chemical plant can be improved at very low capital and operational cost.

When the SO₃ converter is a part of an H₂S0₄ manufacturing chemical plant, the SO₃ is nominally input into an Oleum Tower at 1 10-130°C. As a consequence of the lower converter temperature enabled by the aforementioned CSG unit, it becomes easier to achieve the required 1 10-130°C.

The process enhancement as described above can be utilized in various applications. Block diagrams for the various applications including the manufacture of H₂S0₄, and SO₃ are shown in figures 2 and 3. Process for H2SO4 Manufacture Using Liquid SO3

In a specific innovative application of the aforementioned process enhancement, the aforementioned CSG-based system for producing SO₂ and SO₃ is used to efficiently produce liquid SO₃ with liquid S0₂ as a solvent with further application in the manufacture of high-grade H₂S0₄. This process of manufacturing SO₃ or H₂S0₄ according to the invention is divided into three parts:

Part A: Manufacturing liquid S0₂ without compression or refrigeration

Part B: Converting liquid SO₂ into liquid SO₃ using pure oxygen and isothermal catalytic converter having cesium activated catalyst Part C: Conversion of SO₃ to H₂S0₄ using demineralised water Figure 3 shows a block diagram for application of the present invention for producing liquid SO₃ (parts A and B described above) from an existing Sulfuric acid plant. The figure shows liquid SO₃ and liquid sulfur plants that produce liquid S0₂, which is then converted using a catalyst and dry air from the drying tower into SO₃, which is passed through an Oleum tower after which it is dissolved into liquid phase producing H₂S0₄ and SO3 and H2S2O7.

The process of manufacturing SO₃ according to the invention yields greater quantities of SO₃ than existing plants. This is because in the process of the present invention, SO₃ is first absorbed in H₂S0₄ and then condensed to yield gaseous SO₃ at a higher yield. Process for Manufacture of Sulfonation Compounds

In another innovative application of the aforementioned CSG-based process, the S0₂ and S0₃ produced therein is used in the augmentation of the manufacture of the aforementioned sulfonation compounds. A typical example of such process augmentation is to produce the sulfonation compound called Sulfamic Acid (NH₂S0₂OH) by reaction of Ammonia (NH ) & S0 . The reaction carried out is \] | : + SO: = NH₂S0₂OH, Δ H = -685,9 kJ/mol.

In some embodiments, the S0₃ produced by the CSG and the S0₃ converter is used with S0₂ as a solvent for S0₃. The heat of reaction is removed by evaporation of liquid S0₂, which is injected in the reactor by a metering system after calculating the quantity based on the latent heat for the given temperature and pressure at which the reaction takes place. In order to transfer the product by overflow, additional liquid SO? is provided to form a slurry, the amount of which will vary from case to case.

Isothermal converter:

This section describes the innovative application of the aforementioned CSG in the production of liquid (condensed) S0₂, and pure liquid (condensed) S0₃ with SO?, as a solvent. It has been described previously in the disclosure how the CSG can be used to augment SO? production by injecting the CSG-produced S0₂ into the SO₂ stream generated by the Sulfur burning furnace. In a different pure-S0₂ process, the S0₂ produced by the CSG can be fed directly into the next stage (nominally the SO₃ converter).

In an example of such a process, whereas the S0₂ mixture in the earlier process is at about 1.1 Atmospheres, the pure-S0₂ process would have S0₂ at 6-8 Atmospheres (6-8 Kg/cm2) and 360 °C. Under such high pressure, it becomes possible to condense S0₂ while leaving the residual S0₂ in the gaseous state. As a result, the process enables the production of pure SO₃ in liquid form. Note that this process is enabled by the production of pure S0₂ at high pressure by the CSG unit. Given that this process produces pure SO₃, its use in the manufacture of high-grade H₂S0₄ can lead to significant process simplifications. For example, it would become possible to avoid having to use an Oleum Tower altogether in such a process.

Detailed Plant Description

Figure 4 shows the process to manufacture SO₃ and I hSO . using a new plant. As shown in the figure it requires:

1. a metering system for liquid sulphur and pure oxygen, and

2. a metering system for gaseous S0₂

3. a multipass catalytic converter and catalyst

4. a counter current heat exchanger

5. a thermic fluid system

6. a boiler at Pressure 10 kg/cm²with accessories and controls

7. an SO₂ condenser

8. a dedicated cooling tower 9. a depressurising reactor (from 6-8 kgs to atmospheric pressure.)

10. a chilling plant

11. a condenser for sulphur dioxide using chilled brine

12. an alkali scrubber

As shown in Figure 4, the liquefied S0₂ produced using the process of the present invention and pure oxygen are supplied to a condensation reaction chamber containing a catalytic converter which is kept at a pressure of 6-8 kg/cm2. This produces liquefied S0 by condensation, which is later depressurised to yield liquid S0₃. The remnants of the mixture of SO?, and 0₂ with traces of S0₃ are recycled into the reaction chamber carrying catalyst. The catalyst is preferably Cesium-activated vanadium pentoxide.

It is evident that the invention has at least the following embodiments: 1. A process for the manufacture of SO₂ in higher concentrations in chemical plants producing SO₃, H₂S0₄, or sulfonation compounds, said process comprising the step of passing gaseous SO₃ through liquid sulfur.

2. A process for the manufacture of SO? as disclosed in embodiment 1, wherein said liquid sulfur is nominally maintained at 140 °C. 3. A process for the manufacture of S0₂ as disclosed in embodiments 1 and 2, wherein said SO? generated is augmented with SO? generated by any other processes such as sulfur burning furnaces to generate an augmented mixture of S0₂, said SO?, generated from the furnaces being at a temperature in the range of 950 °C to 1 100 °C.

A process for the manufacture of S0₂ as disclosed in embodiment 3 wherein the concentration of said augmented mixture of SO?, is further supplied to downstream converter units to convert gaseous S0₂ into gaseous S0₃, said converter units being maintained at a temperature between 360 °C to 380

°C using thermic fluid for removal of exothermic heat.

A process for the manufacture of SO? as disclosed in embodiment 4 wherein the augmented mixture of SO? is at a temperature of 600-800 °C.

A process for the manufacture of concentrated SO₃ based on the manufacture of concentrated SO? as disclosed in embodiments 1 through 5 wherein said SO? is reacted with O? in an isothermal catalytic converter in the presence of a catalyst to produce said concentrated SO₃.

A process for the manufacture of concentrated SO₃ as disclosed in embodiment 6 wherein a Vanadium Pentoxide-activated catalyst is used.

A process for the manufacture of concentrated SO₃ as disclosed in embodiment 6 wherein a Cesium-activated catalyst is used.

A process for the manufacture of H₂S0₄ wherein the SO3 generated from said isothermal catalytic converter as disclosed in embodiments 7 or 8 is introduced into an oleum tower to produce liquid SO3 as an intermediate step. A process for the manufacture of H₂SO₄ as disclosed in embodiment 9 wherein said liquid SO3 is introduced to a glass-lined reactor where it is reacted with demineralized water to produce liquid H₂S0₄.

A process for the manufacture of H₂S0₄ as disclosed in embodiment 10 wherein thermic fluid is used as a coolant for said glass lined reactor.

A process for the manufacture of liquefied S0₂ using the gaseous S0₂ manufactured in processes of embodiments 1 to 5, wherein said S0₂ is liquefied using condensation reaction carried out at room temperature and at a pressure of 6-8 atmospheres, and without further compression or refrigeration.

A process for the manufacture of liquefied SO₃ using the liquid SO₂ as produced in the process of embodiment 12, wherein said liquid S0₂ is converted into pure liquid SO₃ using pure 0₂ in the aforementioned isothermal catalytic converter.

A process for the manufacture H₂S0₄ wherein the liquid SO3 as obtained in the process of embodiment 13 is con verted into H₂S0₄ using demineralised water.

A process for the manufacture of a sulfonation compound wherein the intermediates SO₂ and SO₃ used in the sulfonation process are manufactured using the processes as disclosed in embodiments 1 through 13. A process for the manufacture of a sulfonation compound as claimed in claim 15, wherein liquid SO₃ of process of embodiment 13 is added in a quantity of 0, 1% to 5% (by weight) to liquid SO₂ of claim 12. A process specifically for the manufacture of Sulfamic Acid wherein the SO₃ produced using the processes as disclosed in embodiments 1 through 13 is reacted with Ntk.

While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

Claims

A process for the manufacture of SO? in higher concentrations in chemical plants producing S0₃, H₂S0₄, or sulfonation compounds, said process comprising the step of passing gaseous S0₃ through liquid sulfur.

A process for the manufacture of SO? as claimed in claim 1, wherein said liquid sulfur is nominally maintained at 140 °C.

A process for the manufacture of S0₂ as claimed in claims 1 and 2, wherein said S0₂ generated is augmented with S0₂ generated by any other processes such as sulfur burning furnaces to generate an augmented mixture of SO₂, said S0₂ generated from the furnaces being at a temperature in the range of 950 °C to 1 100 °C.

A process for the manufacture of S0₂ as claimed in claim 3 wherein the concentration of said augmented mixture of SO? is further supplied to downstream converter units to convert gaseous SO₂ into gaseous SO₃, said converter units being maintained at a temperature between 360 °C to 380

°C using thermic fluid for removal of exothermic heat.

A process for the manufacture of S0₂ as claimed in claim 4 wherein the augmented mixture of S0₂ is at a temperature of 600-800 °C.

A process for the manufacture of concentrated SO₃ based on the manufacture of concentrated SO₂ as claimed in claims 1 through 5 wherein said S0₂ is reacted with 0₂ in an isothermal catalytic converted in the presence of a catalyst to produce said concentrated SO₃.

7. A process for the manufacture of concentrated S0₃ as claimed in claim 6 wherein a Vanadium Pentoxide-activated catalyst is used,

8. A process for the manufacture of concentrated SO₃ as claimed in claim 6 wherein a Cesium-activated catalyst is used.

9. A process for the manufacture of H₂SO₄ wherein the SO¾ generated from said isothermal catalytic converter as claimed in claims 7 or 8 is introduced into an oleum tower to produce liquid SO₃ as an intermediate step.

10. A process for the manufacture of H₂S0₄ as claimed in claim 9 wherein said liquid SO3 is introduced to a glass-lined reactor where it is reacted with demineralized water to produce liquid H₂S0₄.

11. A process for the manufacture of H₂S0₄ as claimed in claim 10 wherein thermic fluid is used as a coolant for said glass lined reactor.

12. A process for the manufacture of liquefied S0₂ using the gaseous S0₂ manufactured in processes of claims 1 to 5, wherein said S0₂ is liquefied using condensation reaction carried out at room temperature and at a pressure of 6-8 atmospheres, and without further compression or refrigeration.

13. A process for the manufacture of liquefied SO3 using the liquid S0₂ as produced in the process of claim 12, wherein said liquid S0₂ is converted into pure liquid SO₃ using pure 0₂ in the aforementioned isothermal catalytic converter.

14. A process for the manufacture H₂S0₄ wherein the liquid SO3 as obtained in the process of claim 13 is converted into H₂S0₄ using demineralised water.

15. A process for the manufacture of a sulfonation compound wherein the intermediates SO2 and SO3 used in the sulfonation process are manufactured using the processes as claimed in claims 1 through 13.

16. A process for the manufacture of a sulfonation compound as claimed in claim 15, wherein liquid SO₃ of process of claim 13 is added in a quantity of 0, 1% to 5% (by weight) to liquid SO2 of claim 12.

17. A process specifically for the manufacture of Sulfamic Acid wherein the SO₃ produced using the processes as claimed in claims 1 through 13 is reacted with Hj.