Claus Process(Tail Gas Application)

A&D PI2 Concept for China Specialities of Market in Chinarecovering elemental sulfur from gaseous hydrogen sulfide.
Raw Materials and Products
Gases with a H2S content of over 25 % are suitable
for the recovery of sulfur in Claus plants.
These gases may also contain hydrogen cyanide,
hydrocarbons, sulfur dioxide or ammonia.
They mainly originate from physical and
chemical gas treatment units (Rectisol, Purisol
and amine scrubbers) in refineries, gasification
or synthesis gas plants.
for manufacturing medicine, cosmetics, fertilizers
and rubber products.
PGC302 Claus Application
Sour refinery gas
Sour gas from salt production plant
Sour gas from coal gasification
H2S: > 25 %.
T control
> 850 °C
2 H2S+S02 3/2 S2+2 H2O
Ratio 2 : 1 IMPORTANT
60-70 % output of S
Cooled to liquid S
Thermal and catalytic section
In the thermal section H2S containing gas is converted in a lower stöchiometric combustion at temp. of > 850 °C so that
elementary S is falling out in the cooling vessel.
Claus gases (acid gas), which aren´t containing combustible gases with the exception of H2S, are combusted directly in the combustion chamber.
The not converted H2S is reacting together with SO2 to elementary sulfur.
Normally 60-70 % of the elementary S which is built in this process is received in this first step.
The main portion of the hot gas of the combustion chamber is flowing through the process gas cooler and is cooled down so that the converted sulfur is condensed.
The heat of the process gas is used to produce high or low pressure steam.
The condensed sulfur is collected after the outlet of the process gas cooler.
To both gas streams (SWS+Acid gas) it is added an accurate
amount of air, to guarantee that all hydrocarbons - also NH3 - are completely burned and additionally also 1/3 of the H2S content is reacting to SO2.
In the OxyCLaus process oxygen is used inestead of air to
get an accurate air ratio.
205 to
230°C
Catalytic Step
= Activated Alumina
1. Heating
130 to
170°C
1.+2.
or desulphurization downstream
In the catalytic section more non reacted molecular sulfur is produced in the following step in the claus reactor.
By this process extension the output of sulfur is optimized. The catalytic production of molecular sulfur consists of three prartial steps:
1. Heating
3. Condensation
These three steps can be repeated in any way. For technical reasons in maximum 3 reactors are used. If after the claus plant a incinerator or a tailgas purification (TGTU) is used mostly only two catalytical steps are used.
Heating is necessary to avoid S condensation in the catalyser bed and therefore a pollution of the catalyzer.
The cold gas from process gas cooler and the hot gas form the bypass are mixed to get the needed temperature.
Contrary to the thermal reaction the catalytic reaction is exotherm so that only low temperature are required to force this reaction.
The reacted process gas is flowing to the sulfur condenser and is cooled down to 130 to 170 °C. Steam is produced from the heat.
Before storage or further steps the liquid streams are added to a degaser (e.g. Aquisulf- process) and the dissolved gases are separated.
The waste gas of the claus process which is containing combustible constituents (H2S, H2, CO) will be burned in an incinerator or a new step of desulfirization is attached.
Amount of Sulfur received using this process: > 97 % (2 catalytic steps)
Steam which is built: >2.6 t steam / t recovered sulfur
Analysis for enhanced Claus processes
O2
Tail Gas Analysis for Process Optimisation
For proper control of a Claus process , the hydrogen sulphide ( H2S ) and sulphur dioxide ( SO2 ) must be measured in tail gas.
Major problem Sample gas is saturated with sulfur vapour
Plugging of sample lines and analyzer
Further problem Due to the presence of CO2 and HC, COS and CS2 will be formed.
Concentrations difficult to predict
Changing of burner temperature.
CO2 and CS2 interfere UV analysis of SO2 and H2S.
Closed
H2O
SO2
COS
H2S
CO2
N2
Customer
Country
Qty.
Analyser
Analysis
BEB
Germany
5
PGC302
ELF Antar
NEAG
Germany
1
1
Interference by elem. S
less experiences with
sample conditioning system
Proven technology with high reliability, long term stability, many references
Safe protection : Backpurge to clean analyzer and sample lines in case of any problem
with low temperature, power failure.. As well as during maintenance works.
Easy operation , remote operation
Easy maintenance , less frequently
No UV-lamp, longer stability, no expensive spare parts regularely needed
No interference by sulfur, COS CS2 using chromatographic separation
Comprehensive self diagnosis
DCS-coupling using MODBUS
Good value for money

Claus Process(Tail Gas Application)

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