Title of Invention

METHOD FOR ISOLATING HYDROGEN SULFIDE FROM COKE OVEN GAS WITH THE SUBSEQUENT RECOVERY OF ELEMENTAL SULFUR IN A CLAUS PLANT

Abstract The invention relates to a method for isolating hydrogen sulphide from coke-oven gas with the subsequent recovery of elemental sulphur in a Claus plant. The hydrogen sulphide is eliminated from the coke-oven gas-by-gas washing using absorption liquid. During the regeneration of the loaded absorption liquid, hydrogen sulphide is accumulated in concentrated form and is fed to the Claus plant. Said Claus plant comprises a Claus boiler, a waste-heat boiler, in addition to a reactor, which forms an additional catalyst stage. According to the invention, the Claus plant is operated with a single reactor, which operates at a working temperature of below 250 °C. The process gas that exits the reactor is returned after the deposition of elemental sulphur with a non-reacted residual concentration of hydrogen sulphide to the coke-oven gas that is to be cleaned, prior to the gas washing stage. (FIG. - 1)
Full Text Method for isolating hydrogen sulfide from
coke oven gas with the subsequent recovery of elemental
sulfur in a Claus plant
Specification:
The invention relates to a method for isolating hydrogen sulfide
from coke oven gas with subsequent recovery of elemental sulfur
in a Claus plant, in which the hydrogen sulfide is removed from
che coke oven gas by means of gas scrubbing, using an absorption
liquid, the charged absorption liquid is regenerated and, in
this connection, hydrogen sulfide that accumulates in
concentrated form is passed to the Claus plant,
wherein the hydrogen sulfide is reacted with oxygen in the
air, in a Claus boiler of the Claus plant, forming
elemental sulfur,
wherein the process gas that leaves the Claus boiler is
cooled to the temperature required for condensation of the
sulfur, in a waste heat boiler, heated after the sulfur has
been precipitated, and passed to a reaction oven of the
Claus plant, in which sulfur compounds are converted to
elemental sulfur on a catalyst, and
wherein the process gas that leaves the reaction oven is
cooled to a temperature required for condensation of the
sulfur, and the condensed sulfur is precipitated.
Coke oven gas contains hydrogen sulfide, which must be removed
before use in a gas scrubber. In the regeneration of the
charged absorption liquid used for gas scrubbing/ hydrogen
sulfide occurs in concentrated form, and is converted to
elemental sulfur in a subsequent Claus plant. The core piece of
the Claus plant is a boiler having a combustion chamber, where
hydrogen sulfide is converted to elemental sulfur with oxygen,
at high temperatures of more than 800°0. The basic reaction of
the process is
The reaction is greatly exothermic and therefore very
temperature-dependent. In accordance with the reaction
equilibrium, about 70% of the hydrogen sulfide converts to
elemental sulfur, which is precipitated by means of cooling of
the process gas in a subsequent waste heat boiler, by means of
condensation. In subsequent reaction ovens, which are also
referred to as catalyst stages, residual contents of hydrogen
sulfide and sulfur dioxide are converted to sulfur on catalysts,
in accordance with the reaction equation
The Claus reactors are operated at temperatures below 350°C.
Within the framework of the known measures, the Claus plant is
always configured with at least two Claus reactors, switched in
series and operated at different temperatures, in order to
achieve high sulfur yields. Between the Claus reactors switched
in series, an intermediate cooling is provided, for the
precipitation of elemental sulfur. A Claus plant having the
structure described and having the purpose of use indicated is
described in Ullmanns Encyklopadie der technischen Chemie
(Ullmann"s encyclopedia of Technical Chemistry), Vol. 21, pages
8 to 13.
A Claus plant consisting of a Claus boiler and cwo subsequent
cacalyst stages with intermediate cooling systems is complicated
in terms of apparatus. The invention is based on the task of
reducing the apparatus expenditure by means of modifying the
method.
Proceeding from the method described initially, the task is
accomplished according to the invention, in that the Claus
plant is operated with only a single reaction oven, and that a
working temperature of less than 250°C is set in this oven, and
that the process gas that leaves the reaction oven, after
precipitation of the condensed sulfur, is passed back into the
coke oven gas to be cleaned, ahead of the gas scrubbing, with a
residual content of hydrogen sulfide that was not converted in
the reaction oven. Preferably, the reaction oven is operated in
a temperature range between 200°C and 230°C.
According to the invention, the Claus plant is configured only
with a Claus boiler and a single subsequent catalyst stage,
which is operated at a lower temperature, in comparison with the
state of the art. In this connection, it is accepted that the
converted part of H2S, wich reference to the hydrogen sulfide
amount passed to the Claus plant, is less than in the state of
the art, when using a Claue plant having two or more catalyst
stages. According to the invention, it was recognized, when
considering the process as a whole, that higher sulfur contents
in the waste gas of the Claus plant are tolerable if the waste
gas is passed back to the coke oven gas to be cleaned, and
subjected to gas scrubbing together with it. The gas scrubbing
is designed in such a manner that a higher content of. hydrogen
sulfide in the coke oven gas has no effect on the hydrogen
sulfide content in the cleaned gas. In this regard, the gas
scrubbing makes a second or third catalyst stage of the Claus
plant superfluous. By means of the method according to the
invention, the Claus plant can be configured in very simple
manner, in terms of System technology. The control technology
side of the Claus plant is also significantly simplified.
Further embodiments of the method according to the invention are
described in the dependent claims 3 to 6, and are explained in
the following, using an exemplary embodiment. The figures
schematically show
Fig. l a greatly simplified block schematic of the method
according to the invention,
Pig. 2 a Claus plant chat is used within the scope of the
method according to the invention.
According to the method shown in Fig. l in the form of a block
schematic, hydrogen sulfide is separated from coke oven gas COG
and converted to elemental sulfur s in a subsequent Claus plant.
The hydrogen sulfide is removed from coke oven gas by means of
gas scrubbing 1 using an absorption liquid. The charged
absorption liquid 2 is regenerated in a stage 3. In this
connection, hydrogen sulfide occurs in concentrated form, in the
form of vapor, which is passed to a Claus plant 4. In the Claus
plant 4, hydrogen sulfide is converted to elemental sulfur S,
which is drawn off in liquid form. Furthermore, a process gas 5
occurs, which contains a non-reacted residual content of
hydrogen sulride and is passed back to the coke oven gas COG to
be cleaned, ahead of the gas scrubbing l.
The structure of the Claus plane 4 is shown in Fig. 2. The
fundamental structure of this plant includes a Claus boiler 6, a
waste heat boiler 7, as well as a reaction oven 8 having a
catalyst bulk material 9. An application stream 10 that
contains hydrogen sulfide is fed into a combustion chamber 13 of
the Claus boiler 6, together with air 11 and heating gas 12, and
converted at temperatures of approximately 1200°C, in an
exothermic reaction, forming elemental sulfur. The process gas
that leaves the Claua boiler 6 is cooled to a temperature of
less than 170°C, which is required for condensation of the
sulfur, in the waste heat boiler 7. Elemental sulfur S is
condensed and precipitated. After precipitation of the sulfur,
the process gas 14 is heated, by mixing in a partial stream 15
that is taken from the Claus boiler 6, and passed to the
reaction oven 8 of the Claus plant. In the reaction oven 8,
hydrogen sulfide and sulfur dioxide are converted to elemental
sulfur on catalycts 16. The reaction oven 8 is operated at a
working temperature of less than 250°C, preferably in a
temperature range between 200°C and 230°C.
From Fig. 2, it is evident that the Claus plant 4 is configured
with only a single reaction oven 8. The process gas that leaves
the reaction oven 8 is cooled to a temperature required for
condensation of the sulfur. After precipitation of the
condensed sulfur, the process gas 5, which still contains a
residual content of hydrogen sulfide, is passed back into the
coke oven gas COG to be cleaned, ahead of the gas scrubbing 1.
According to a preferred embodiment of the method according co
the invention, the Claus plant 4 is operated in such a manner
that 80 to 85% of the hydrogen sulfide is converted to elemental
sulfur and drawn off as a condensate.
A boiler lined with a refractory material, lying horizontally,
is used as the Claus boiler 6, which has a combustion chamber 13
and a catalyst chamber having a catalyst bulk material 9, which
follows horizontally and is delimited on both sides by gas-
permeable checker bricks 17.
In the waste heat boiler 7, both the gas stream that exits from
the Claus boiler 6, having a temperature of about 1200°C, and
the process gas stream that exits from the reaction oven 8,
having a temperature of less than 250°C, are cooled to a
temperature below the condensation temperature of elemental
sulfur. In this connection, a low-tension steam 18 is generated.
The waste heat boi1er 7 hae a first tube bundle 19 composed, of
heat exchanger tubes, through which the process gas that exits
from the Claus boiler 6 flows. The waste heat boiler 7
furthermore has a second tube bundle 20 composed of heat
exchanger tubes, through which the process gas that exits from
the reaction oven 8 flows. The tube bundles 19, 20 are disposed
in a common steam generator chamber. Elemental sulfur already
condenses in the waste heat boiler 7 and is drawn off from the
waste heat boiler 7 and subsequent precipitators 21 in liquid
form.
To heat the process gas 14 passed to the reaction oven 8, a
partial stream 15 is branched out of the Claus boiler. The
branch line is connected to the circumference of a downstream-
side chamber 22 of the Claus boiler 6, which chamber is lined
with refractory material, and opens into the process gas line
that is adjacent to the boiler. In the orifice region of the
branch line, a valve body is disposed in adjustable manner, with
which the amount flow of the gas stream that exits from the
branch line can be. regulated. The valve body and a setting
device assigned to the valve body are cooled by the process gas
14 that is passed through the process gas line, so that usual
metallic components can be used for the valve body.
WE CLAIM:
1. Method for isolating hydrogen sulfide from coke oven gas with
subsequent recovery of elemental sulfur in a Claus plant (4) in which
the hydrogen sulfide is removed from the coke oven gas by means of
gas scrubbing (1) using an absorption liquid, the charged absorption
liquid (2) is regenerated and, in this connection, hydrogen sulfide
that accumulates in concentrated form is passed to the Claus plant
(4) wherein the hydrogen sulfide is reacted with oxygen In the air, in
a Claus boiler (6) of the Claus plant (4) forming elemental sulfur,
wherein the process gas that leaves the Claus boiler (6) is cooled to
the temperature required for condensation of the sulfur, In a waste
heat boiler (7) heated after the sulfur has been precipitated, and
passed to a reaction oven (8) of the Claus plant (4) in which sulfur
compounds are converted to elemental sulfur on a catalyst, and
wherein the process gas that leaves the reaction oven (8) is cooled to
a temperature required for condensation of the sulfur, and the
condensed sulfur Is precipitated, characterized In that the Claus plant
(4) is operated with only a single reaction oven (8) and that a
working temperature of less than 250°C is set in this oven, and that
the process gas (5) that leaves the reaction oven (3) after
precipitation of the condensed sulfur, is passed back into the coke
oven gas to be cleaned, ahead of gas scrubbing, with a residua!
content of hydrogen sulfide that was not converted in the reaction
oven.
2.Method as claimed in claim 1, wherein the reaction oven is
operated in a temperature range between 200°C and 230°C.
3.Method as claimed in claim 1 or 2, wherein a boiler lined with a
refractory material, lying horizontally, is used as the Claus boiler,
which has a combustion chamber and a catalyst chamber having a
catalyst bulk material, which follows horizontally and is delimited on
both sides by gas-permeable checker bricks.
4. Method as claimed in one of claims 1 to 3, wherein the waste heat
boiler has a first tube bundle composed of heat exchanger tubes,
through which the process gas that exits from the Claus boiler flows,
that the waste heat boiler has a second tube bundle composed of
heat exchanger tubes, through which the process gas that exits from
the reaction oven flows, and that the tube bundles are disposed in a
common steam generator chamber, in which low-tension steam is
generated.
5.Method as claimed In one of claims 1 to 4, wherein elemental sulfur
is drawn off from the waste heat boiler in liquid form.
6.Method as claimed in one of claims 1 to 5, wherein a partial stream
is branched out of the hot process gas that leaves the Claus boiler,
and mixed into the process stream that is passed to the reaction
oven, to heat it.
Method for isolating hydrogen sulfide from coke
oven gas with the subsequent recovery of elemental
sulfur in a Claus plant
The invention relates to a method for isolating hydrogen sulfide
from coke-oven gas with the subsequent recovery of elemental
sulfur in a Claus plant (4), the hydrogen sulfide is eliminated from
the coke-oven gas by washing, using an absorption liquid (2).
During the regeneration of the loaded absorption liquid, hydrogen
sulfide is accumulated In concentrated form and is fed to the Claus
plant (4). Said Claus plant (4) comprises a Claus boiler (6), a
waste-heat boiler (7) in addition to a reactor (8), which forms an
additional catalyst stage. According to the invention, the Claus
plant is operated with a single reactor (8), which operates at a
working temperature of below 250°C. The process gas (5) that
exits the reactor is returned after the deposition of elemental
sulfur with a non-reacted residual concentration of hydrogen
sulphide (5) to the coke-oven gas that is to be cleaned prior to the
washing stage (1).

Documents:


Patent Number 217465
Indian Patent Application Number 00060/KOLNP/2005
PG Journal Number 13/2008
Publication Date 28-Mar-2008
Grant Date 26-Mar-2008
Date of Filing 19-Jan-2005
Name of Patentee UHDE GMBH
Applicant Address FRUEDRUCG-UHDE-STRASSE 16 44141 DORTMUND GERMANY
Inventors:
# Inventor's Name Inventor's Address
1 THIELERT, HOLGER WESTERWLKSTRASSE 38 44379 DORTMUND GERMANY
PCT International Classification Number B M61
PCT International Application Number PCT/EP03/004899
PCT International Filing date 2003-05-10
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10233819.1 2002-07-25 Germany