Reactor and process for preparing hydrogen sulphide

Abstract

The present invention relates to a reactor and to a process for synthesis of hydrogen sulphide from elemental sulphur and hydrogen at elevated pressure and elevated temperature. The invention further relates to the use of the reactor for preparation of hydrogen sulphide in high yield and with a low H.sub.2S.sub.x content.

Claims

1. A reactor for continuous preparation of hydrogen sulphide by exothermic reaction of sulphur and hydrogen to form a final product gas mixture P.sub.final comprising hydrogen sulphide and sulphur at elevated temperature and elevated pressure relative to standard conditions, said reactor, comprising: a lower reactor region including a sulphur melt, and a gas collecting region configured for accommodating a product gas mixture P.sub.final at elevated temperature and elevated pressure relative to standard conditions, wherein the reactor comprises at least two non-pressure-bearing first caverns and a supply device providing a controlled supply of pressurized gaseous hydrogen to the lower reactor region per first caverns, the caverns being configured for at least temporary accommodation of a product gas mixture P.sub.1 which forms in exothermic reaction and comprises hydrogen sulphide, sulphur and hydrogen, and the reactor additionally comprises a non-pressure-bearing second cavern which is arranged above the first cavern and is configured for at least temporary accommodation of the product gas mixture P.sub.1 formed in the first cavern and for formation of further hydrogen sulphide by exothermic reaction of sulphur and hydrogen to form a product gas mixture P.sub.2.

2. The reactor according to claim 1, wherein at least one of the second caverns comprises at least one supply device suitable for controlled supply of pressurized gaseous hydrogen.

3. The reactor according to claim 1, wherein the reactor additionally comprises a non-pressure-bearing third cavern, and optionally further, correspondingly suitable caverns arranged above the second cavern.

4. The reactor according to claim 3, wherein at least one of the pressure-bearing third or further suitable caverns has a greater volume than each of the first caverns, and/or in that at least one of the pressure-bearing third or further suitable caverns has lower heat removal for construction reasons than each of the first caverns.

5. The reactor according to claim 1, wherein the reactor additionally comprises a non-pressure-bearing installed device configured for continuous transfer of the total amount of product gas mixture P.sub.u formed in the lower reactor region to the gas collecting region and, in the case that a catalyst is present in the installed device, the device is configured for reaction of sulphur and hydrogen still present in the product gas mixture P.sub.u to hydrogen sulphide.

6. The reactor according to claim 5, wherein one, more than one or all of the installed devices for transfer of the product gas mixture Pu from the lower reactor region to the gas collecting region are arranged in terms of construction such that, after sufficient filling of the lower reactor region with a sulphur melt, they are in thermal contact with the sulphur melt such that, when the installed device contains a catalyst, the catalyst is cooled by transfer of heat to the sulphur melt.

7. The reactor according to claim 1, wherein the reactor comprises an inner wall which, in the course of operation of the reactor with involvement of the space between outer reactor wall and the inner wall, obtains continuous circulation of the sulphur melt according to the airlift pump principle.

8. The reactor according to claim 1, wherein the reactor additionally comprises: a reflux condenser configured for condensation of the sulphur present in the product gas mixture P.sub.final, an input line configured for transport of the product gas mixture P.sub.final from the gas collecting region to the reflux condenser and a return line configured for return of the condensed sulphur to the reactor.

9. A process for preparing hydrogen sulphide by exothermic reaction of sulphur with hydrogen at elevated temperature and elevated pressure relative to standard conditions to form a product gas mixture P.sub.final comprising hydrogen sulphide and sulphur, the process comprising: supplying pressurized hydrogen into a sulphur melt located in a lower reactor region of a pressurized reactor, the hydrogen supplied being accommodated at least partly, together with sulphur converted from the sulphur melt to the gaseous state, by at least two non-pressure-bearing first caverns, wherein the pressurized gaseous hydrogen is supplied by supply devices per first caverns; at least temporarily leaving the hydrogen and the sulphur in the first caverns, so as to form, in exothermic reaction, a product gas mixture P.sub.1 comprising hydrogen sulphide, sulphur and hydrogen; at least temporarily leaving the product gas mixture P.sub.1 formed in the first caverns in a second cavern, so as to react the sulphur and hydrogen present in the product gas mixture P.sub.1 with formation of further hydrogen sulphide to give a product gas mixture P.sub.2 and collecting the product gas mixture P.sub.final in a gas collecting region.

10. The process according to claim 9, wherein at least a portion of the hydrogen supplied into the sulphur melt is accommodated directly by the second cavern.

11. The process according to claim 9, wherein the product gas mixture is accommodated and left at least temporarily in a third or higher cavern, so as to react the sulphur and hydrogen present in the product gas mixture P.sub.2 with formation of further hydrogen sulphide.

12. The process according to claim 9, wherein the total amount of the product gas mixture P.sub.u formed in the lower reactor region is continuously transferred to the gas collecting region by a non-pressure-bearing installed device, wherein by use of a catalyst in the installed device the sulphur and hydrogen present in the product gas mixture P.sub.u are reacted with formation of further hydrogen sulphide.

13. The process according to claim 12, wherein the catalyst is cooled by heat transfer of the heat of reaction, released by the reaction of sulphur and hydrogen in the catalyst, to the sulphur melt.

14. The process according to claim 12, wherein the proportion of hydrogen sulphide in the product gas mixture P.sub.u prior to introduction into the installed device containing the catalyst is at least 60% of the gas volume.

15. The process according to claim 9, further comprising condensing and recycling directly into the reaction, sulphur present in the product gas mixture P.sub.final.

16. The process according to claim 9, wherein the preparation of hydrogen sulphide is performed at a pressure of 5 to 15 bar.

17. The process according to claim 9, wherein the temperature of the sulphur melt is 400 to 450 C.

18. The process according to claim 9, wherein the sulphur melt is circulated continuously according to the airlift pump principle.

19. The process according to claim 9, wherein the hydrogen sulphide has a sulphane content not exceeding 600 ppm.

Description

EXAMPLES

Example 1

Comparative Example

(1) 1000 l (STP)/h of hydrogen were introduced continuously via a frit at the base into a tube having an internal diameter of 5 cm which had been filled with liquid sulphur up to a height of 1 m. The consumption of sulphur was compensated for by further metered addition of liquid sulphur, while keeping the fill level constant. Sulphur removed from the product gas stream by condensation was recycled into the upper region of the tube in liquid form. Above the liquid sulphur, jacketed thermocouples for temperature measurement were provided at intervals of 10 cm. While the reactor was heated to 400 C. electrically via the outer wall, a homogeneous temperature of about 397 C. was present within the sulphur. However, the thermocouples above the sulphur showed a maximum temperature of 520 C. In addition, above the liquid sulphur, new material samples made from standard stainless steel (1.4571) were provided at the location of maximum temperature. After an operating time of about 400 h, the material samples were removed and showed severe corrosion phenomena in the form of flaking and weight loss.

Example 2

Comparative Example

(2) Example 1 was repeated, except that the height of the liquid sulphur was raised to 4 m. The value of the maximum temperature above the liquid sulphur was maintained. Severe corrosion phenomena likewise occurred on the material samples.

Example 3

Comparative Example

(3) Example 2 was repeated, except that 15% by weight of a pulverulent Co.sub.3O.sub.4MoO.sub.3/Al.sub.2O.sub.3 catalyst were suspended in liquid sulphur. The value of the maximum temperature above the liquid sulphur was maintained. Severe corrosion phenomena likewise occurred on the material samples.

Example 4

Comparative Example

(4) The preparation of hydrogen sulphide was performed in a pilot plant. The pilot reactor had a height of approx. 5.5 m, a diameter of approx. 0.5 m and a volume of approx. 0.8 m.sup.3. The pilot plant was equipped with four caverns of equal dimensions in series. 70 m.sup.3 (STP)/h of hydrogen were metered in continuously via the hydrogen feeds, which corresponded to a hydrogen load of 3700 m.sup.3 (STP)(H.sub.2)/(m.sup.3 (cavern volume).Math.h) based on the single cavern. Spent sulphur was replenished under fill level control. Sulphur removed from the product gas stream by condensation was recycled into the reactor in liquid form. The pressure in the reactor was 12 bar. The temperature in the liquid sulphur was 430 C. The residence time in the caverns was 5 s in each case. The H.sub.2 conversion through homogeneous reaction in the caverns was about 90%. By means of thermocouples installed in a fixed manner in the reactor, the temperature within the caverns and above the sulphur melt was measured. The highest temperature measured in the caverns under these circumstances was 479 C. Above the liquid sulphur phase, no commencement of a homogeneous reaction was discernible. The gas temperature above the liquid sulphur corresponded virtually to the temperature of the liquid sulphur, such that there were no increased demands on the material of the pressure-bearing jacket in the region of the gas phase above the liquid sulphur.

(5) The gas phase then flowed to and through the catalyst in the installed device, as shown schematically in FIG. 1 (7). The hydrogen remaining was then converted virtually completely over the catalyst (overall conversion of H.sub.2: 99.86 mol %). The gas hourly space velocity on the catalyst was 3700 m.sup.3 (STP)(H.sub.2)/(m.sup.3 (bed volume of catalyst).Math.h). There was virtually no occurrence of corrosion in the form of flaking or weight loss on the material used. Material samples made from standard stainless steel (1.4571) which were installed for comparative purposes had only moderate corrosion attack.

LIST OF REFERENCE NUMERALS

(6) (1) Reactor (2) Lower reactor region (3) Sulphur melt (4) First caverns (5, 5a) Hydrogen supply device to the first caverns (6) Gas collecting region (7) Installed device for transfer of gas from the lower reactor region to the gas collecting region, optionally containing a catalyst (8) Second caverns (9, 9a) Hydrogen supply device to the second caverns (10) Third caverns (11) Inner wall (12) Gas space of the first caverns (13) Gas space of the second caverns (14) Gas space of the third caverns (15) Gas space of the lower reactor region (16) Intermediate tray (17) Orifice (18) Orifice (19) Orifice