GB2183228A - Reducing the sulphur content of Claus off-gas - Google Patents
Reducing the sulphur content of Claus off-gas Download PDFInfo
- Publication number
- GB2183228A GB2183228A GB08528070A GB8528070A GB2183228A GB 2183228 A GB2183228 A GB 2183228A GB 08528070 A GB08528070 A GB 08528070A GB 8528070 A GB8528070 A GB 8528070A GB 2183228 A GB2183228 A GB 2183228A
- Authority
- GB
- United Kingdom
- Prior art keywords
- gas
- claus
- reducing
- hydrogen sulphide
- heat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8603—Removing sulfur compounds
- B01D53/8612—Hydrogen sulfide
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/16—Hydrogen sulfides
- C01B17/164—Preparation by reduction of oxidic sulfur compounds
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biomedical Technology (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Treating Waste Gases (AREA)
Abstract
The sulphur content of Claus off-gas is reduced by heating the off-gas to a temperature above 175 DEG C, passing heated off-gas with reducing gas over a reducing catalyst in a reactor to obtain a gas mixture including reduced off-gas, removing in an absorber hydrogen sulphide from the gas mixture, and burning in a thermal incinerator the remaining gas mixture to obtain hot flue gas, wherein heat contained in the hot flue gas is passed indirectly to the Claus off-gas so as to heat said off-gas with the use of a heat exchanger.
Description
SPECIFICATION
Reducing the sulphur content of claus off-gas
The invention relates to reducing the sulphur content of Claus off-gas which is a gas mixture leaving a Claus plant. In such a Claus plant elemental sulphur is prepared from hydrogen sulphide by partial oxidation of hydrogen sulphide to obtain sulphur dioxide, followed by reaction of the sulphur dioxide with the remaining part of the hydrogen sulphide in the presence of a catalyst.
Since the amount of sulphur recovered is about 98% the Claus off-gas leaving the Claus plant still contains sulphur in the form of amongst others hydrogen sulphide, sulphur dioxide, sulphur vapour and carbonyl sulphide. The temperature of the Claus off-gas is in the range of from 1000C to 160 C.
Known is a process of reducing the sulphur content of Claus off-gas comprising heating the
Claus off-gas to a temperature above 175 C, passing heated off-gas with a reducing gas over a reducing catalyst to obtain a gas mixture including reduced off-gas, removing hydrogen sulphide from the gas mixture, the incinerating the remaining gas mixture substantially free of hydrogen sulphide to convert all traces of hydrogen sulphide.
In the known process, the Claus off-gas is heated by an external heat source.
It is an object of the present invention to provide a process of reducing the sulphur content of
Claus off-gas, wherein the Claus off-gas is heated independently of an external heat source, and wherein the amount of heat available to heat the Claus off-gas is balanced with heat required under all operating conditions.
To this end the process of reducing the sulphur content of Claus off-gas according to the invention comprising the steps of heating the Claus off-gas to a temperature above 175 C, passing heated off-gas with reducing gas over a reducing catalyst to obtain a gas mixture including reduced off-gas, removing hydrogen sulphide from the gas mixture, and incinerating the remaining gas mixture substantially free of hydrogen sulphide to obtain hot flue gas, wherein heat contained in the hot flue gas is passed indirectly to the Claus off-gas so as to heat said off-gas.
It is observed that it is known to heat the Claus off-gas by mixing it with hot flue gas from a burner arranged in a conduit through which the Claus off-gas is passed to a reactor filled with reducing catalyst. A disadvantage thereof is that a larger amount of gas should be processed, to wit Claus off-gas and flue gas. Moreover, a burner can only be operated to produce an amount of heat in a well defined ranges.
The invention will now be described by way of example with reference to the Figure. The apparatus for carrying out the process of reducing the total sulphur content of Claus off-gas comprises a reactor 1 filled with a reducing catalyst to which is connected supply conduit 2, an absorber 3 connected to the reactor 1 by means of connecting conduit 5, a cooler 6 arranged in the connecting conduit 5, and a thermal incinerator 8 connected to the absorber 3 by means of connecting conduit 9 and provided with a flue gas discharge conduit 10.
The apparatus further comprises a heat exchanger 11 arranged in the supply conduit 2 and the flue gas outlet conduit 10 so as to allow passing indirectly heat contained in gas passing through the flue gas discharge conduit 10 to gas passing through the supply conduit 2.
To the absorber 3 there are connected a lean absorbent conduit 15 for supplying lean absorbent to the absorber 3 and a fat absorbent conduit 16 for removing fat absorbent from the absorber 3.
To the terminal incinerator 8 there are connected a fuel conduit 18 and an oxidant conduit 19.
To the supply conduit 2 there is connected a reducing gas supply conduit 20.
During normal operation Claus off-gas including sulphur dioxide is passed through the supply conduit 2, via the heat exchanger 11, where the Claus off-gas is heated, to the reactor 1.
Supplied to the Claus off-gas is reducing gas comprising free hydrogen and/or free carbon monoxide via the reducing gas supply conduit 20. In the reactor 3 at least part of the sulphur dioxide is reduced to hydrogen sulphide and a gas mixture including reduced off-gas is allowed to flow through the connecting conduit 5 via the cooler 6 where the gas mixture is cooled to the absorber 3. To remove hydrogen sulphide from the gas mixture, the gas mixture is contacted in the absorber 3 with a liquid and regeneratable absorbent for hydrogen sulphide supplied to the absorber 3 via the lean absorbent conduit 15. After contacting fat absorbent loaded with hydrogen sulphide is removed from the absorber 3 via the fat absorbent conduit 16.
The fat absorbent is passed to a regenerator (not shown) to remove the hydrogen sulphide therefrom, and regenerated absorbent is passed to the lean absorbent conduit 15.
The remaining gas mixture which is substantially free of hydrogen sulphide leaves the absorber 3 via connecting conduit 9 and is passed to the thermal incinerator 8, to which also fuel and air are supplied through the fuel conduit 18 and the oxidant conduit 19 respectively. In the thermal incinator 8 the gas mixture substantially free of hydrogen sulphide is incinerated to oxidize traces of hydrogen sulphide present in the gas mixture, and the hot flue gas obtained from burning the gas mixture is passed through the flue gas discharge conduit 10 to the heat exchanger 11, where the heat contained in the hot flue gas is passed indirectly to the Claus off-gas passing through the supply conduit 2 so as to heat said off-gas. From the heat exchanger 11, the flue gas discharge conduit 10 extends to a stack (not shown).
The temperature of the Claus off-gas is measured by means of a temperature measurement device 23 before the off-gas enters the reactor 1. If the temperature of the off-gas exceeds a predetermined value, valve 24 in bypass conduit 25 is opened so that a part of the hot flue gas bypasses the heat exchanger 11.
Instead of supplying the reducing gas to the Claus off-gas after the off-gas has been heated, the reducing gas can be supplied to the off-gas before heating the off-gas.
Instead of a thermal incinerator as shown in the Figure, the apparatus can be provided with a catalytic incinerator.
The temperature of the Claus off-gas entering the reactor should be above 175 C, suitably the temperature is in the range of from 1 800C to 350 C. The pressure in the reactor is substantially atmospheric. Suitable reducing catalysts are sulphided Group VI and/or Group VIII metal catalysts supported on an inorganic oxidic carrier, for example Ni/Mo,'Al203 or Co/Mo/Al203 catalysts.
The gas hourly space velocity of the gas, passing through the reactor is between 500 and 10000 Nm3 per m3 of catalyst per hour, wherein 1 Nm3 equals 1 m3 gas at 0 C and 0.1 MPa.
The reducing gas should be supplied in such an amount that the ratio between reducing gas and sulphur dioxide is of from 3:1 to 15:1.
The liquid and regeneratable absorbent for hydrogen sulphide is suitably an aqueous solution of an amine or a substituted amine. The temperature in the absorber is suitably in a range of from 50C to 50 C.
The temperature of the hot flue gas leaving the thermal incinator will be in the range of from 600 C to 800 C, and if a catalytic incinator is used in the range of from 3000C to 450 C.
Instead of removing hydrogen sulphide from the gas mixture leaving the reactor by means of a liquid and regeneratable absorbent, hydrogen sulphide can be removed by adsorbing it on a suitable adsorbent, such as a molecular sieve or an oxide of a metal for example ZnO.
In an alternative embodiment of the invention heat contained in the hot flue gas is first passed to a heat exchange medium, such as hot oil, from which the heat is subsequently transferred to the Claus off-gas to be heated.
Claims (3)
1. Process of reducing the sulphur content of Claus off-gas comprising the steps of heating the Claus off-gas to a temperature above 175 C, passing heated off-gas with reducing gas over a reducing catalyst to obtain a gas mixture including reduced off-gas, removing hydrogen sulphide from the gas mixture, and incinerating the remaining gas mixture substantially free of hydrogen sulphide to obtain hot flue gas, wherein heat contained in the hot flue gas is passed indirectly to the Claus off-gas so as to heat said off-gas.
2. Process as claimed in claim 1, wherein the Claus off-gas is passed through a heat exchanger to which at least part of the hot flue gas is supplied.
3. Process substantially as described in the specification with reference to the Figure.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08528070A GB2183228A (en) | 1985-11-14 | 1985-11-14 | Reducing the sulphur content of Claus off-gas |
| NL8602655A NL8602655A (en) | 1985-11-14 | 1986-10-23 | REDUCE THE SULFUR CONTENT OF CLAUSE GAS. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08528070A GB2183228A (en) | 1985-11-14 | 1985-11-14 | Reducing the sulphur content of Claus off-gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8528070D0 GB8528070D0 (en) | 1985-12-18 |
| GB2183228A true GB2183228A (en) | 1987-06-03 |
Family
ID=10588210
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08528070A Withdrawn GB2183228A (en) | 1985-11-14 | 1985-11-14 | Reducing the sulphur content of Claus off-gas |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2183228A (en) |
| NL (1) | NL8602655A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0721917A1 (en) * | 1995-01-12 | 1996-07-17 | Daelim Engineering Co. Ltd. | Catalyst for reducing sulphurous acid gas, manufacturing method thereof and method for recovering sulphur using the same |
-
1985
- 1985-11-14 GB GB08528070A patent/GB2183228A/en not_active Withdrawn
-
1986
- 1986-10-23 NL NL8602655A patent/NL8602655A/en not_active Application Discontinuation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0721917A1 (en) * | 1995-01-12 | 1996-07-17 | Daelim Engineering Co. Ltd. | Catalyst for reducing sulphurous acid gas, manufacturing method thereof and method for recovering sulphur using the same |
Also Published As
| Publication number | Publication date |
|---|---|
| NL8602655A (en) | 1987-06-01 |
| GB8528070D0 (en) | 1985-12-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |