FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
SYNTHESIS GAS COOLER
THERMAX LIMITED
an Indian Company
of D-13, MIDC Industrial Area, R.D. Aga Road,
Chinchwad, Pune - 411019, INDIA
Inventors:
BASARGEKAR SUDHEER SHYAMRAO A. KRISHNAKUMAR
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

Field of the Disclosure:
The present disclosure relates to a cooling system for cooling synthesis gas obtained from high pressure gasification process, more particularly, the present disclosure relates to a water tube type natural circulation synthesis gas cooler.
Background of the Disclosure:
Conventionally, a fire tube type cooler is used for cooling the synthesis gas obtained from high pressure gasification process, wherein the synthesis gas obtained from high pressure gasification process flows through the tubes that are surrounded by a cooling medium such as water. However, the fire tube type coolers for cooling the synthesis gas are in-efficient in utilizing the heat energy of the synthesis gas. Furthermore, the use of fire tube type cooler for cooling the synthesis gas has various drawbacks associated with use thereof. For example, the fire tube type cooler are difficult to clean and maintain. More specifically, the cleaning of the heat transfer surfaces in case of the fire tube type cooler is a tedious, time consuming and complicated task. Further, as the heat transfer surfaces of the fire tube type cooler get scaled, the heat transfer efficiency of the fire tube type cooler is substantially reduced, thereby leading to energy losses and inefficient utilization of the heat energy carried by the synthesis gas.
Accordingly, there is need for a synthesis gas cooler that efficiently cools the synthesis gas obtained from high pressure gasification process. Further, there is need for a synthesis gas cooler that facilitates self cleaning and online

cleaning of deposits deposited on the heat transfer surfaces of the synthesis gas cooler. Still further, there is a need for a synthesis gas cooler that provides better thermal performance by providing optimal heat transfer area. Further, there is need for a synthesis gas cooler that minimizes energy losses and synthesis gas losses by completely utilizing the heat energy of the synthesis gases.
Objects:
Some of the objects of the present disclosure which at-least one embodiment is able to satisfy, are described herein below:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a synthesis gas cooler for cooling synthesis gas obtained from high pressure gasification.
Another object of the present disclosure is to provide a synthesis gas cooler that facilitates self cleaning and online cleaning of deposits deposited on the heat transfer surface.
Still another object of the present disclosure is to provide a synthesis gas cooler that provides better thermal performance by providing optimal heat transfer area.

Yet another object of the present disclosure is to provide a synthesis gas cooler that is convenient to handle and maintain.
Another object of the present disclosure is to provide a synthesis gas cooler that ensures an enhanced ratio of heat transfer area to volume.
Still another object of the present disclosure is to provide a synthesis gas cooler that exhibits improved heat transfer performance and higher heat transfer efficiency.
Yet another object of the present disclosure is to provide a synthesis gas cooler that possesses simplified design and optimal dimensions.
Another object of the present disclosure is to provide a synthesis gas cooler that minimizes energy losses and synthesis gas losses by completely utilizing the heat energy of the synthesis gases.
Still another object of the present disclosure is to provide a synthesis gas cooler that is efficient than fire tube type coolers.
SUMMARY
A synthesis gas cooling system is disclosed in according to one embodiment of the present disclosure. The synthesis gas cooling system includes a heat exchanger assembly for facilitating heat exchange between the hot synthesis gases and cooling fluid and an online cleaning system. The heat exchanger assembly includes a steam drum, a first shell and a second shell. The first

shell is provided with an inlet for receiving the hot synthesis gases. The first shell includes a first heat exchange section, a first operative bottom header, a first operative top header, and an outlet. The first heat exchange section is disposed inside the first shell and facilitates passage of the hot synthesis gases there-through. In accordance with an embodiment, the first heat exchange section includes a plurality of membrane panels. The first operative bottom header supplies the cooling fluid around the first heat exchange section for facilitating heat exchange between the cooling fluid and the hot synthesis gas, wherein the cooling fluid partially extracts heat from the synthesis gas flowing through the first heat exchange section and in the process gets evaporated. The first operative top header receives the evaporated cooling fluid from the first shell and supplies the evaporated cooling fluid to the steam drum. The outlet is disposed at an operative bottom of the first shell for discharging partially cooled synthesis gases.
The second shell is connected with the first shell via a connecting section for receiving the partially cooled synthesis gases leaving the first shell. The second shell includes a second heat exchange section, a second operative bottom header, a second operative top header and an outlet. The second heat exchange section is disposed inside the second shell and facilitates passage of the partially cooled synthesis gases there-through. The second operative bottom header supplies the cooling fluid around the second heat exchange section for facilitating heat exchange between the cooling fluid and the partially cooled synthesis gas, wherein the cooling fluid extracts heat from the partially cooled synthesis gas flowing through the second heat exchange section and in the process gets evaporated. The second operative top header receives the evaporated cooling fluid from the second shell and supplies the

evaporated cooling fluid to the steam drum. The outlet is disposed at an operative top of the second shell for discharging cooled synthesis gases therefrom. The online cleaning system transmits vibrations to the second heat exchange section for facilitating disengaging of ash adhering thereto, thereby causing online cleaning of the second heat exchange section/
Typically, the first heat exchange section includes a plurality of membrane panels.
Similarly, the second heat exchange section includes a plurality of vertical tube blanks.
Typically, the online cleaning system is a rapping arrangement that transmits vibrations to the second heat exchange section for facilitating disengaging of ash adhering thereto, thereby causing online-cleaning of the second heat exchange section.
Generally, the second heat exchange section is disposed sideways of the first heat exchange section and is connected to the first heat exchange section via the connecting section, wherein the connecting section is a refractory lined duct.
Alternatively, the second heat exchange section is disposed below the first heat exchange section.

In accordance with an embodiment, the synthesis gas cooling system further includes one or more hoppers disposed at an operative bottom of the connecting section for facilitating removal of the ash.
Typically, the steam drum includes a moisture separator through which steam is passed before entering a steam pipe and a feed water pump that delivers required flow of water to the steam drum using an automatic level control.
Generally, the synthesis gas cooling system further includes a control system for adjusting steam flow and maintaining steam pressure inside the drum at required value, thereby ensuring that the steam temperature in a circulation pipe and a coil is maintained at constant value well above dew point of the synthesis gas.
Typically, the synthesis gas cooling system further includes a flow regulator for ensuring natural circulation inside said synthesis gas cooling system and protecting said heat transfer surfaces from high temperature radiation from the refractory lined duct.
Brief Description:
The disclosure will now be explained in relation to the accompanying drawing:
Figure 1 illustrates a schematic representation of a synthesis gas cooler in accordance with an embodiment of the present disclosure.

Detailed Description:
The disclosure will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
Referring to Figure 1 of the accompanying drawings, a synthesis gas cooler 1000 for cooling synthesis gas obtained from high pressure gasification process is illustrated. The synthesis gas cooler 1000 includes a heat exchanger assembly 100, a feed water pump 300 (not shown in Figure 1), valves and Instruments 400 (not shown in Figure 1). The exchanger assembly 100 includes membrane panels 110 with bottom header 120, a down-comer pipe 130, a steam drum 140, a top header 150, a riser pipe 160, a first refractory lined steel shell 170, a plurality of vertical tube banks 180, a bottom water header 190, a down comer pipe 200, a top steam header 210,

riser pipe 220, a second refractory lined steel shell 230, a refractory lined steel duct 240 and a pair of hoppers 250.
Referring to Figure 1 of the accompanying drawings, the synthesis gas to be cooled passes over the.membrane panels 110, where the heat from, the synthesis gas is extracted, the membrane panels 110 are connected to the bottom header 120 at one end and to the top header 150 at the other end. The synthesis gas enters the system at a pressure upto 30 bar g and a temperature of about 800 to 1000 degree centigrade. The bottom header 120 is connected to the steam drum 140 via the down-comer pipe 130 and the top header 150 is connected to the steam drum 140 via the riser pipe 160 for conveying the steam generated at the membrane panels 110 to the steam drum 140. The water entering the system i.e. steam drum 140 is at ambient temperature or at de-aerator temperature, if it is used. In accordance with an embodiment, the. membrane panels 110 are encased in a refractory lined steel shell 170 and the headers 150 and 120 are provided outside the refractory lined steel shell 170. However, the membrane panels 110 along with the headers 150 and 120 can be encased in a refractory lined steel shell 170 designed to withstand the required pressure. As the synthesis gas passes through the membrane panels 110, the synthesis gas cools down to around 500 to 600 degree centigrade in the heat exchanger and generates steam from the water flowing through the membrane panels 110. The use of the membrane panels 110 permits optimum sizing for use at higher temperatures and self cleaning of the deposits on the heat transfer surfaces.
The vertical tube banks 180 receive water from a bottom water header 190 that is connected to the steam drum 140 via the down comer pipe 200 and

receives water there-from. Further, as the water received by the vertical tube banks 180 flows through the vertical tube banks 180, it is heated by the synthesis gas flowing over the vertical tube banks 180, thereby causing cooling of the synthesis gas and generating stearn from the water received by the vertical tube banks 180. The steam from the vertical tube banks 180 is discharged to the top steam header 210 and connected thereto via the riser pipe 220. The tube bank assembly is housed in a refractory lined steel shell 230 designed to withstand the required pressure. The synthesis gas flowing over the vertical tube banks 180 cools down to about 250 to 300 degree centigrade in this heat exchanger. The steam collected at the steam drum 140 is having a pressure of 35 bar g (saturated). The ash is disengaged from the tube surface, using a rapping mechanism which transmits the vibration through metal strips attached to the tube banks 180, thereby facilitating online cleaning of deposits deposited on the heat transfer surface and enhancing the heat transfer there-through.
The steam drum 140 is connected to the two heat exchangers by down comers 130 and 200 and risers 220 and 160. The down comers, the risers and the steam drum are fitted with mountings as, required for operation and safety of the boiler.
The tube bank assembly may be located below the panel membrane assembly or sideways with a connecting refractory lined steel duct 240 disposed between the tube bank assembly and the panel membrane assembly. Depending on the arrangement, the boiler i.e. syngas cooler can be provided with one or more hoppers 250 for removal of the ash.

The feed water pump delivers required flow of water to the drum using automatic level control. The steam is passed through a moisture separator located in the drum before entering the steam pipe. The steam pressure in the drum is maintained at required value by adjustment of steam flow, thereby ensuring that the steam temperature in the circulation pipe and coil is maintained at constant value well above the dew point of the synthesis gas. In case of power failure, the natural circulation effect ensures that the heat transfer surface is not subjected to high temperature radiation from the refractory.
Technical Advancements and Economic Significance:
The synthesis gas cooler of the present disclosure can cool synthesis gas obtained from high pressure gasification. The synthesis gas cooler of the . present disclosure facilitates self-cleaning and online cleaning of deposits deposited on the heat transfer surface thereof. The synthesis gas cooler of the present disclosure provides better thermal performance by providing optimal heat transfer area. The synthesis gas cooler of the present disclosure is convenient to handle and maintain. Furthermore, the synthesis gas cooler of the present disclosure exhibits improved heat transfer performance and higher heat transfer efficiency. The synthesis gas cooler of the present disclosure incorporates a simplified casing design and has optimal dimensions. Further, the synthesis gas cooler of the present disclosure minimizes energy losses and synthesis gas losses by completely utilizing the heat energy of the synthesis gases.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure and the claims unless there is a statement in the specification to the contrary.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters,

dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

We Claim:
1. A synthesis gas cooling system comprising:
• a heat exchanger assembly adapted to facilitate heat exchange between the hot synthesis gases and cooh'ng fluid, said heat exchanger assembly comprising: o a steam drum;
oa first shell provided with an inlet for receiving the hot synthesis gases, said first shell comprising:
■ a first heat exchange section disposed inside said first shell and adapted to facilitate passage of the hot synthesis gases there-through;
■ a first operative bottom header adapted to supply the cooling fluid around said first heat exchange section for facilitating heat exchange between said cooling fluid and the hot synthesis gas, wherein the cooling fluid partially extracts heat from the synthesis gas flowing through said first heat exchange section and in the process gets evaporated;
■ a first operative top header adapted to receive the evaporated cooling fluid from said first shell and supplying said evaporated cooling fluid to said steam drum; and
■ an outlet disposed at an operative bottom of said first shell for discharging partially cooled synthesis gases;

oa second shell connected with said first shell via a connecting section for receiving said partially cooled synthesis gases leaving said first shell, said second shell comprising:
■ a second heat exchange section disposed inside said second shell and adapted to facilitate passage of said partially cooled synthesis gases therethrough;
■ a second operative bottom header adapted to supply the cooling fluid around said second heat exchange section for facilitating heat exchange between said cooling fluid and said partially cooled synthesis gas, wherein the cooling fluid extracts heat from said partially cooled synthesis gas flowing through said second heat exchange section and in the process gets evaporated;
■ a second operative top header adapted to receive the evaporated cooling fluid from said second shell and supplying said evaporated cooling fluid to said steam drum; and
■ an outlet disposed at an operative top of said second shell for discharging cooled synthesis gases therefrom; and
• an online cleaning system for said second heat exchange section.

2. The synthesis gas cooling system as claimed in Claim 1, wherein said first heat exchange section comprises a plurality of membrane panels.
3. The synthesis gas cooling system as claimed in Claim 1, wherein said second heat exchange section comprises a plurality of vertical tube banks.
4. The synthesis gas cooling system as claimed in Claim 1, wherein said online cleaning system is a rapping arrangement adapted to transmit vibrations to said second heat exchange section for facilitating disengaging of ash adhering thereto, thereby causing online-cleaning of said second heat exchange section.
5. The synthesis gas cooling system as claimed in Claim 1, wherein said second heat exchange section is disposed sideways of said first heat exchange section and is connected to said first heat exchange section via said connecting section, wherein said connecting section is a refractory lined duct.
6. The synthesis gas cooling system as claimed in Claim 1, wherein said second heat exchange section is disposed below said first heat exchange section.
7. The synthesis gas cooling system as claimed in Claim 1, wherein said synthesis gas cooling system further comprises one or more hoppers disposed at an operative bottom of said connecting section for facilitating removal of the ash.

8. The synthesis gas cooling system as claimed in Claim 1, wherein said steam drum comprises a moisture separator through which steam is passed before entering a steam pipe and a feed water pump that delivers required flow of water to said steam drum using an automatic level control.
9. The synthesis gas cooling system as claimed in Claim 1, wherein synthesis gas cooling system further comprises a control system for adjusting steam flow and maintaining stearn pressure inside said drum at required value, thereby ensuring that the steam temperature in a circulation pipe and a coil is maintained at constant value well above dew point of said synthesis gas.
lO.The synthesis gas cooling system as claimed in Claim 1, further comprises a flow regulator for ensuring natural circulation inside said synthesis gas cooling system and protecting said heat transfer surfaces from high temperature radiation from the refractory lined duct.