FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
1 TITLE OF THE INVENTION :
A SIMULATOR SYSTEM FOR DESULPHURIZATION OF COKE OVEN GAS AND A GAS TREATMENT METHOD USING SUCH SYSTEM.
2 APPLICANT (S)
Name : JSW STEEL LIMITED.
Nationality : An Indian Company.
Address : Jindal Mansion, 5-A, Dr. G. Deshmukh Marg, Mumbai - 400 026,
State of Maharastra, India.
3 PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to a simulator system to determine the most suitable operating parameters and catalysts required for desulphurization of coke oven gas in recovery type coke oven. More particularly, the present invention relates to a pilot scale simulator system to conduct off-line experiments and to optimize the most suitable operating parameters for desired sulphur separation in desulphurization unit in recovery coke oven byproduct plant. The pilot scale simulator system according to the invention thus serves as an effective research tool to predetermine the operating process parameters and the catalyst concentrations required for sulphur separation, making the actual plant operation more effective as well as productive, by on one hand ensuring recovery of sulphur from carbonization gases and on the other hand provide clean gas free of sulphur, making it suitable for recycling.
BACKGROUND ART
It is well known in recovery coke oven plant of iron and steel plants, the volatile gases generated during carbonization are collected, processed in byproduct plant, and recovered which is called "coke oven gases. The coke oven exhaust gases contain impurities, such as tar, naphthalene, ammonia, hydrogen sulphide etc. The major portion of liquid impurities, such as tar and naphthalene are separated in gas condensation area. Further, the gas is cleaned in Electrostatic Tar Precipitator (ETP), Desulphurization unit and Ammonia decomposition unit. Finally, the cleaned gas is collected in gas holder. The main byproducts of the system are tar, sulphur and ammonia (Ammonia decomposes to Hydrogen and Nitrogen).
The main function of the desulphurization unit is to extract hydrogen sulphide (H2S) from the gas by scrubbing with Ammonical liquor, followed by regeneration of elemental sulphur from the scrubbed solution. Desulphurization unit mainly consists of Desulphurization Tower (DT), Regeneration Tower (RT), and Solution Circulation Tower (SCT).
In the conventional process of desulphurization, Coke oven gas from the gas condensation area enters the pre cooling tower to cool and contract in volume..The gas entering the desulphurization unit is scrubbed with Ammonical liquor of selective

alkalinity so that H2S along with some ammonia and cyanide is scrubbed. The scrubbed gas is further carried to ammonia scrubber area. The scrubbed solution (40°C) is passed to SCT where selective catalyst is added. The scrubbed solution is then pumped to the bottom of the RT along with the compressed air so that sulphur separates in the presence of air and catalyst as sulphur foam which is centrifuged to get sulphur paste. The solution free from sulphur is recycled to DT for further scrubbing.
The deficiencies of the existing desulphurization method are that the process parameters could not be selected properly so that sulphur could be separated from coke oven gas. Thus in spite of presence of H2S gas in coke oven gas, regeneration of sulphur was nil. It was thus necessary to determine the optimum operating conditions that would enable complete recovery of sulphur.
There has been therefore a need in the related art to developing a device and method that would facilitate optimization of operating parameters that enable recovery of sulphur from coke oven gas. The device of the invention would provide means for off-line experimentation with variation and control over a range of important parameter values favorable for sulphur removal and also identify reasons responsible for non recovery and rectify the same.
OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to providing a pilot scale simulator system to optimize the operating parameters for sulphur recovery in desulphurization process for gasses in recovery coke oven.
A further object of the present invention is directed to providing a pilot scale simulator system to conduct off-line experiments with wide range of control of parameters to determine the most suitable operating parameters to ensure sulphur removal from coke oven gas.

A still further object of the present invention is directed to providing a pilot scale simulator system for desulphurization of coke oven gas which would provide means to physically observe the scrubbed solution and impurities present therein.
A still further object of the present invention is directed to providing a pilot scale simulator system for desulphurization of coke oven gas which would restrict the flow of impurities to the Solution Circulation Tank.
A still further object of the present invention is directed to providing a pilot scale simulator system for desulphurization of coke oven gas which would help to identify the reasons for non recovery of sulphur and rectify the issues related with the separation of elemental sulphur.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a simulator system for
desulphurization of coke oven gas comprising:
a desulphurization tower;
a regeneration tower;
a solution circulation tank ;
a chiller adapted to vary the temperature in said solution circulation tank;
a collector tank adapted to restricted flow of impurities to the solution circulation
tank;
all adapted to facilitate optimization of operating parameters that enable recovery of sulphur from coke oven gas.
A further aspect of the present invention is directed to a simulator system for desulphurization of coke oven gas wherein the gas scrubbed by Ammonical liquor is collected in said collector tank, and the solution made to flow to said solution circulation tank where catalyst is added, the solution is pumped to regeneration tank along with compressed air to separate sulphur.

A still further aspect of the present invention is directed to say simulator system for desulphurization of coke oven gas which is adapted for control of wide range of parameters including: (a)Temperatures of solution, (b)Temperatures in chiller, (c )Flow rate of solution, (d)Amount and type of catalyst, and (e)Air flow.
Yet another aspect of the present invention is directed to said simulator system for desulphurization of coke oven gas wherein said collector tank comprises a viewing glass preferably Perspex Glass to observe the color of the scrubbed solution and impurities.
A still further aspect of the present invention is directed to a simulator system for desulphurization of coke oven gas wherein said collector tank comprises of 3 different taps, through which impurities can be restricted to flow to the solution circulation tank.
According to yet another aspect of the present invention is directed to said simulator system for desulphurization of coke oven gas wherein said solution circulation tank comprises an agitator for uniform mixing of the catalyst including selected from PDS, Tannin and Hydroquinone.
A further aspect of the present invention is directed to a method of coke oven gas
treatment involving the simulator system for desulphurization of coke oven gas
comprising:
carrying out the simulation study based on the coke oven gas parameters in said
simulator and then optimizing the operating parameters for effective sulphur
recovery.
A still further aspect of the present invention is directed to a method of coke oven gas treatment wherein said simulator is used to rectify the issue related with the separation of elemental sulphur and/or identify the reasons for non-recovery of

sulphur, including (a) High concentration of catalyst and (b) High temperature of the solution in the solution circulation tank.
According to yet another aspect of the present invention is directed to say method of coke oven gas treatment comprising the steps of identifying the optimum levels of the operating parameters for sulphur separation and /or alternate effective catalysts and thereafter carrying out the sulphur separation involving such optimized operating parameters and/or selective catalyst.
The objects and advantages of the present invention are described in greater details with reference to the following accompanying non limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the schematic block diagram of the conventional desulphurization unit for sulphur removal from coke oven gas showing the different equipments involved.
Figure 2: is the schematic block diagram of the pilot scale simulator according to the present invention capable of monitoring and control of operating parameters to find out the optimum parameters for sulphur removal and recovery.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPAYING FIGURES
The present invention is thus directed to providing a pilot scale simulator to conduct required experimentation with a wide range of control on process parameters for treating coke oven gas for desulphurization so as to determine the optimum operating parameters for desired sulphur removal. This would favors scaling up the parameter values as well as use of catalysts to actual plant scale operation to ensure complete sulphur recovery in coke oven byproduct plant.

Reference is first invited to the accompanying Figure 1 that illustrates the schematic diagram of conventional desulphurization unit in a recovery type coke oven plant. As the name indicates the main function of the desulphurization unit is to extract hydrogen sulphide (H2S) from coke oven gas by scrubbing with Ammonical liquor, following by regeneration of elemental sulphur from the scrubbed solution. Desulphurization unit mainly consists of Desulphurization Tower (DT), Regeneration Tower (RT), and Solution Circulation Tower (SCT).
Following process steps are carried out in the desulphurization plant to remove sulphur from the coke oven gas:
(i) Coke oven gas from the gas condensation area enters the pre cooling tower
where temperature of the gas is reduced from 45°C to 25°C, which reduces
the volume of the gas. (ii) The gas entering the desulphurization tower (DT) flows in counter current
with scrubbing Ammonical liquor of alkalinity 8-9. H2S along with some
ammonia and cyanide is scrubbed. The scrubbed gas is further carried to
ammonia scrubber area. (iii)The scrubbed solution (40°C) is passed to solution circulation tower (SCT)
where catalyst Pthalocyanine cobalt compound (PDS) and Tannin is added.
After SCT, the solution temperature is reduced to 28°C through Heat
Exchangers (HE). (iv)The scrubbed solution is then pumped to the bottom of the regeneration
tower (RT) along with the compressed air. Sulphur separates in the presence
of air and catalyst as sulphur foam, which is centrifuged to get sulphur paste. (v) The solution free from sulphur is recycled to DT for further scrubbing.
Following deficiencies have been found in operation of the existing desulphurization plant:
(a) In spite of H2S content in coke oven gas, regeneration of sulphur could not be achieved.
(b) It was necessary to find out optimum operating conditions that would enable recovery of sulphur from coke oven gas.

In order to over come the deficiencies of the existing system, a pilot scale simulator has been designed and developed by way of the present invention to conduct off-line experiments and to optimize the most suitable operating parameters. The simulator consists of Desulphurization tower(DT), Regeneration tower(RT), Solution circulation tower(SCT), Agitator(AG) for uniform mixing of the catalyst PDS, Tannin and Hydroquinone, Chiller(CH) to vary temperature in SCT and collector tank (CT), which has a viewing glass to observe the color of the scrubbed solution and impurities. CT also consists of 3 different taps, through which impurities can be restricted to flow to the SCT. The gas scrubbed by Ammonical liquor is collected in CT, and the solution was made to flow to SCT where catalyst is added. The solution is pumped to RT along with compressed air to separate sulphur.
Following advantageous features are derived from the pilot scale simulator according to the present invention:
(a) The simulator facilitates optimization of following operating parameters that
enable recovery of sulphur from coke oven gas. A series of experiments have been
conducted to optimize the performance of simulator for sulphur regeneration
/removal from coke oven gas, with wide range of control of parameters, comprising
(i) Temperatures of solution,
(ii) Temperatures in chiller,
(iii) Flow rate of solution,
(iv) Amount and type of catalyst, and
(v) Air flow
(b) Impurities can be observed through Perspex glass in CT.
The results from the above study are presented below. Following Table 1 presents the comparison of plant parameters with simulator parameters wherein simulator parameters could achieve sulphur removal.

Table 1

Parameters Plant Parameters Simulator Parameters
Temp of gas
After PCT 25 -26°C
Gas DT 35-36 °C
Inlet to RT 30-32°C 10-30 °C
After RT 33-35 °C
Catalyst
PDS 70-90 ppm 20-30 ppm
Tannin 200-300 ppm 100-150 ppm
Hydroquinone 50-60 ppm
Alkalinity
Ammonia 11-13 g/l 1-14 g/l
Sodium carbonate 12-14 g/l 8-13 g/l
Solution flow 900-1000 m3/hr 0.1-0.3 m3/nr
Sulphur Generation No Yes
Following Table 2 shows the results of desulphurization operation achieved in pilot scale simulator with parameters varied with PDS and Tannin catalysts:
Table 2:

pH Gas
flow
(m3/hr) Solution
Flow
(Lt/hr) Air Flow (m3/hr) Free NH3
(g/1) Temp <°C) PDS (ppm) Tannin (ppm) Sulphur Generation
9.4 10 337.6 0.23 13.15 22 34.78 114.87 Achieved
8.95 10 275 0.25 12.53 30 19.25 48.93 Achieved

Following Table 3 shows the results of desulphurization operation achieved in pilot scale simulator with parameters varied with PDS and Hydroquinone catalysts:
Table 3:

PH 3as flow Solution Air Free Temp PDS Hydro- Sulphur
(m3/hr) Flow (Lt/hr) Flow (m3/hr) NH3
(g/i) (°C) (ppm) quinone
(ppm) Generation
9.3 10 320 0.24 13.1 24 79.5 65 Achieved
The above results clearly show that sulphur generation could be achieved in pilot scale stimulator with use of varied parameters and treating with alternate catalysts.
It is thus observed that the pilot scale simulator according to the invention is an effective experimental tool for providing practical solutions to issues related with sulphur removal from coke oven gas. The coke oven gas treatment using pilot scale simulator has enabled to rectify the issue related with the separation of elemental sulphur. It also helped to identify the reasons for non-recovery of sulphur, such as:
-High concentration of catalyst;
-High temperature of the solution in the solution circulation tank;
It has been possible to identify the optimum levels of the above parameters that help sulphur separation. It is also possible to demonstrate that alternate catalysts can carry out desulphurization effectively.

WE CLAIM:
1. A simulator system for desulphurization of coke oven gas comprising:
a desulphurization tower;
a regeneration tower;
a solution circulation tank ;
a chiller adapted to vary the temperature in said solution circulation tank;
a collector tank adapted to restricted flow of impurities to the solution circulation
tank
All adapted to facilitate optimization of operating parameters that enable recovery of
sulphur from coke oven gas.
2. A simulator system for desulphurization of coke oven gas as claimed in claim 1 wherein the gas scrubbed by Ammonical liquor is collected in said collector tank, and the solution made to flow to say solution circulation tank where catalyst is added, the solution is pumped to regeneration tank along with compressed air to separate sulphur.
3. A simulator system for desulphurization of coke oven gas as claimed in anyone of claims 1 to 2 adapted for control of wide range of parameters including: (a)Temperatures of solution,
(b)Temperatures in chiller, (c )Flow rate of solution, (d)Amount and type of catalyst, and (e)Air flow .
4. A simulator system for desulphurization of coke oven gas as claimed in anyone of claims 1 to 3 wherein said collector tank comprises a viewing glass preferably Perspex Glass to observe the color of the scrubbed solution and impurities.
5. A simulator system for desulphurization of coke oven gas as claimed in anyone of claims 1 to 4 wherein said collector tank comprises of 3 different taps, through which impurities can be restricted to flow to the solution circulation tank.

6. A simulator system for desulphurization of coke oven gas as claimed in anyone of
claims 1 to 5 wherein said solution circulation tank comprises an agitator for uniform
mixing of the catalyst including selected from PDS, Tannin and Hydroquinone.
7. A method of coke oven gas treatment involving the simulator system for desulphurization of coke oven gas as claimed in anyone of claims 1 to 5 comprising: Carrying out the simulation study based on the coke oven gas parameters in said simulator and then optimizing the operating parameters for effective sulphur recovery.
8. A method of coke oven gas treatment as claimed in claim 7 wherein said simulator is used to rectify the issue related with the separation of elemental sulphur and/or identify the reasons for non-recovery of sulphur, including (a) High concentration of catalyst and (b) High temperature of the solution in the solution circulation tank.
9. A method of coke oven gas treatment as claimed in anyone of claims 7 or 8 comprising the steps of identifying the optimum levels of the operating parameters for sulphur separation and /or alternate effective catalysts and thereafter carrying out the sulphur separation involving such optimized operating parameters and/or selective catalyst.
10. A simulator system for desulphurization of coke oven gas and a method for of
coke oven gas treatment involving the simulator system for desulphurization of
coke oven gas substantially as herein described and illustrated with reference to the
accompanying figures and examples.