FORM 2
THE PATENTS ACT, 1970
{39 OF 1970}
AND
THE PATENT RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10 AND RULE 13)
"ENHANCEMENT OF WASTE HEAT RECOVERY DRIVEN POWER GENERATION
BY CO-FIRING OF SOLID FUELS"
TRANSPARENT ENERGY SYSTEMS PRIVATE LIMITED AN INDIAN NATIONAL "PUSHPA HEIGHTS", 1ST FLOOR, BIBWEWADI CORNER, PUNE-SATARA ROAD, PUNE-411 037, MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION DESCRIBES THE NATURE OF THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION-
The present invention relates to the process of Enhancement of waste heat recovery driven power generation by co-firing of solid fuels. More particularly, the present invention relates to co-firing of fuels to increase the temperature of exhaust gases from vent of clinker cooler in cement plant to increase the efficiency of the waste heat driven power plant.
PRIOR ART:-
The conventional cement manufacturing process consists of clinker cooler wherein ambient temperature air is supplied by forced draft fans for cooling the hot cement clinker. The heat from hot gases generated during the process of cooling of clinker is utilized in several ways as foliowing-
1. Secondary air of highest temperature range between 1200 to 1300 deg C is supplied to Rotary Kiln as preheated combustion air
2. Tertiary Air of relatively lower temperature in the range between 800 to 1000 deg C is supplied to raw feed preheater tower of cement plant,
3. The mid-tap/Vent air of further lower temperature in the range between 250 to 400 deg C is supplied to waste heat recovery system to drive steam rankine cycled based power plant or organic rankine cycle based power plant.
4. There are limitations on the efficiency of the waste heat driven power due to inferior heat rate in range of 3200 to 3700 kcal/kW
5. Further the remaining air from clinker cooler is vented out at temperature of about 150 -230 deg C. The vent air at outlet of waste heat recovery system of temperature about 85-130 deg C is mixed with the clinker cooler vent air of 150-230 deg C. The mixed stream of temperature about 110 - 150 deg C is passed through particulate separation equipment such as electrostatic precipitator/ bag filter where in temperature of the gases drops to about 90 to 100 deg C due to radiation losses. These gases are exhausted to atmosphere through chimney.

LIMITATIONS OF PRIOR ART:-
As described in the prior art,
1, There are limitations on the efficiency of the waste heat driven power due to
inferior heat rate in range of 3200 to 3700 kcal/kW.
2. The power output is limited to typically 4.5 MW - 5.0 MW per Million ton/annum
output of a cement plant.
OBJECT OF THE PRESENT INVENTION:-
Object of present invention aims at the process of Enhancement of waste heat recovery driven power generation by co-firing of solid fuels.
More particularly, the present invention aims improving efficiency of the waste heat driven power plant by co-firing of fuels to increase the temperature of exhaust gases from Vent of clinker cooler in cement plant.
It is also object of present invention to eliminate limitations or drawbacks of the prior art.
STATEMENT OF INVENTION:-
Accordingly invention provides A process for enhancement of waste heat recovery driven power generation by co-firing solid fuels, by increasing the temperature of vent gases of clinker cooler in the cement plant, the process step comprises:
a. The said vent gases at 130 to 230 deg C at outlet of clinker cooler are
supplied to hot air generator by opening first damper in the inlet pipe and
closing second damper in the bypass duct;
b. The solid fuels are combusted in the said hot air generator to elevate the
temperature of these clinker cooler vent gases ;
c. The said hot gases of step (b) are mixed with the clinker cooler mid tap
gases of temperature 350 to 400 deg C by opening third and fourth dampers

of outlet pipe of the said hot air generator and the said mid tap outlet pipe
of clinker cooler respectively resulting the temperature of the gas stream is
raised to about 450 to 500 deg C; and
d. the mixed stream of gases of step ( c) is then supplied to waste heat
recovery heat exchanger to generate steam of temperature 410-450 deg C
and at pressure 24-40 Bar(a) to drive steam rankine cycle power plant or
generate hot thermal oil, or pressurized hot water to drive organic rankine
cycle power plant.
Accordingly invention provides a system for enhancement of waste heat recovery
driven power generation by co-firing solid fuels, by increasing the temperature of
vent gases of clinker cooler in the cement plant comprises a hot air generator
provided with a combustion equipment for combustion of solid fuels having an inlet
and outlet for gas; the said inlet is connected to the vent gas outlet of clinker cooler
to supply vent gas at at 130 to 230 deg C, and the said outlet of said hot air
generator with a first third damper connected to the waste heat recovery heat
exchanger through a T- pipe duct; the mid tap outlet of clinker cooler is joined with a
second fourth damper to said T-pipe duct to mix mid tap outlet gas of temperature
350 to 400 deg C with outlet gas of hot air generator to raise the temperature of
the mixed gas stream to about 450 to 500 deg C ; a third first damper provided
between the said vent gas outlet and inlet of the said hot air generator; a bypass
provided with a forth second damper connected to the said vent gas outlet; the
said heat exchanger enabled to generate steam to drive steam rankine cycle power
plant / for generating hot thermal oil, or pressurized hot water to drive organic
rankine cycle power plant.
DESCRIPTION OF FIGURES:-
Figure 1 Schematic diagram showing waste heat recovery steam generators with coal fired hot air generators enhancing heat recovery.

DETAILED DESCRIPTION OF PRESENT INVENTION:-
The figure 1 shows the schematic representation of the present invention which relates to the process of Enhancement of waste heat recovery driven power generation by co-firing of solid fuels. The figure 1 shows, a typical cement plant incorporating the scheme in the present invention. Figure 1 shows a typical cement plant comprising of preheater cyclone tower (5) for raw feed (28) preheating, a rotary kiln (8) to which preheated raw feed (6) is supplied exhaust gases (7) of which are supplied to preheater tower and a clinker cooler (24) equipped with set of ambient air supply fans (26) which cools the hot clinker (9) discharged by rotary kiln discharging the finished cement clinker (27). The hot air generated in the clinker cooler in the process of clinker cooling is taped at various temperatures and reutilized in cement making process in form of secondary air at about 1300 deg C (10) supplied to rotary kiln (8), tertiary air at about 800 deg C supplied to calciners (11) and mid tap air at about 350 to 400 deg C (12) for waste heat recovery heat exchanger (20). The exhaust hot gases (4) from preheater cyclone tower are supplied to waste heat recovery heat exchanger (3) on preheater, upon heat recovery these gases are supplied by fan (2) to raw mill (1) for raw feed drying and preparation.
According to the present invention, the vent gases (13) at 130 to 230 deg C at outlet of clinker cooler are supplied to hot air generator (14)by opening damper (25) and closing damper (15) in the bypass duct (22). The solid fuels (16) such as coal are combusted in the said hot air generator. As a result the temperature of these clinker cooler vent gases is elevated. These hot gases (29) are mixed with the clinker cooler mid tap gases (12) of temperature 350 to 400 deg C by opening dampers (18) and (17). The temperature of the gas stream (19) is raisedto about 450 to 500 deg C as a result of this mixing. The mixed stream of gases (19) is then supplied to waste heat recovery heat exchanger (20) to generate steam of temperature 410-450 deg C and at pressure 24-40 Bar(a). This steam of high pressure and temperature is used to drive the steam turbine. The scheme can be engineered with turbine that can operate at variable steam temperature and pressure such as to have flexibility to work at lower pressure and temperature of about

375 deg C as well by isolating the hot air generator whenever the co-firing is to be stopped. As a result of the co-firing the power output of the waste heat driven power plant increases by 30-60%. Incremental power output is available at heat rate of less than 3000 kcal/kW with a marginal rise in investment. As a result of increase in the temperature and the heat content of the mid-tap air/vent due to co-firing, more heat shall be recovered in the waste heat recovery system operating on mid-tap air /Vent thereby increasing the power generation.
The typical example case of power generation in case of present invention is shown in table below.

Sr. Description Unit WITH COAL WITHOUT
No FIRING COAL FIRING
1 Heat Source Preheater
2 Exhaust Gas Volumetric Flow at Boiler Inlet Nm3/hr 185000
3 Exhaust Gas Mass Flow at Boiler Inlet kg/hr 264038
4 Exhaust Gas Temperature at Boiler Inlet Deg.C 335
5 Exhaust Gas Temperature at Boiler Outlet Deg.C 200 202
6 Net Total Heat Recovery in Boiler kcal/hr 8974828 8822012
7 Maximum Pressure Drop Across WHRS mmWC 125 125
8 Heat Source Clinker Cooler
9 Exhaust Gas volumetric Flow from
mid tap Nm3/hr 70812
10 Exhaust Gas mass Flow from mid tap kg/hr 91348
11 Exhaust Gas Temperature from mid
tap Deg.C 380

12 Exhaust Gas volumetric Flow at WHRB inlet Nm3/hr 159535 70812
13 Exhaust Gas mass Flow at WHRB inlet kg/hr 205801 91348
14 Exhaust Gas Temperature at WHRB inlet Deg.C 430 380
15 Exhaust Gas Temperature at Boiler Outlet Deg.C 111 80
16 Net Total Heat Recovery in Boiler kcal/hr 15244269 5451419
17 Additional Heat Input by Coal Firing MW 11.18 NA
18 Quantity of Coal Required based on NCV of 4500 kcal/kg kg/hr 2111 NA
19 Specific Additional Heat Input by Coal Firing per KW for additional power Output Kcal/KW 2896 NA
20 Maximum Pressure Drop Across WHRS mmWC 125 125
21 High Pressure Steam Parameters At Superheater
Outlet At
Superheater
Outlet
Pressure kg/cm2a) 30 22
Temperature Deg.C 415 352
Total Quantity kg/hr 28330 17867
22 Low Pressure Steam Parameters At
Superheater
Outlet At
Superheater
Outlet
Pressure kg/cm2a) 4.5 4.5
Temperature Deg.C 185 180
Total Quantity kg/hr 5207 1647
23 HP Steam Required to Ejector kg/hr 400 400
24 Power Generation Equipment - Steam Turbine with Alternator

25 Condenser Type - Water Cooled Condenser
26 Wet Bulb Temperature for WCC Design Deg.C 28 28
27 Design Condensing Pressure kg/cm2(a) 0.11 0.11
28 Gross Electric Power Generation kWe 6500 3220
ADVANTAGES OF PRESENT INVENTION:-
1. The present invention shall improve heat reutilization in cement plant therefore bring down cost of energy required for manufacturing cement
2. The present invention shall improve power generation from waste heat recovery based power plant and to improve heat rate
VARIATIONS POSSIBLE:-
1. In the present invention it is possible to design the scheme with co-firing of fuels such as Coarse / Pulverized Coal, Pet-coke , biomass fuels etc. using any of suitable combustion equipments such as Pulverized Coal Burner, Oscillating Water Cooler Grate etc.
2. In the present invention, it is possible to design the system with variable pressure temperature turbine so that the system can work at reduced load in absence of co-firing.
3. In the present invention, the system could be designed for generating hot thermal oil, or pressurized hot water to drive organic rankine cycle power plant
4. In the present invention, the system could be designed for generating high pressure high temperature superheated steam to drive steam rankine cycle power plant

WE CLAIM:-
1. A process for enhancement of waste heat recovery driven power generation by co-
firing solid fuels, by increasing the temperature of vent gases of clinker cooler in
the cement plant, the process step comprises:
a. The said vent gases at 130 to 230 deg C at outlet of clinker cooler are
supplied to hot air generator by opening first damper in the inlet pipe and
closing second damper in the bypass duct;
b. the solid fuels are combusted in the said hot air generator to elevate the
temperature of these clinker cooler vent gases ;
c. the said hot gases of step (b) are mixed with the clinker cooler mid tap
gases of temperature 350 to 400 deg C by opening third and fourth dampers
of outlet pipe of the said hot air generator and the said mid tap outlet pipe
of clinker cooler respectively resulting the temperature of the gas stream is
raised to about 450 to 500 deg C;
d. the mixed stream of gases of step ( c) is then supplied to waste heat
recovery heat exchanger to generate steam of temperature 410-450 deg C
and at pressure 24-40 Bar(a) or generate hot thermal oil, or pressurized hot
water to drive organic rankine cycle power plant.
2. A process as claimed in claim 1 wherein the steam of high pressure and temperature of step (d) is supplied steam turbine.
3. A process as claimed in claims 1 and 2 wherein the said solid fuel combusted co-firing of fuels such as Coarse / Pulverized Coal, Pet-coke, biomass fuels and like.
4. A process as claimed in claims 1 to 3 wherein the said hot gas / air generator provided with combustion equipments such as Pulverized Coal Burner, Oscillating Water Cooler Grate and like.

5. A process as claimed in claim 1 wherein the outlet pipe duct of clinker cooler connected to inlet of hot air generator provided with the said first damper and a bypass pipe duct before the said first damper to operate the turbine operable at variable steam temperature and pressure such as to have flexibility to work at lower pressure and temperature of about 375 deg C as well by isolating the hot air generator whenever the co-firing is to be stopped.
6. A system for enhancement of waste heat recovery driven power generation by co-firing solid fuels, by increasing the temperature of vent gases of clinker cooler in the cement plant comprises a hot air generator provided with a combustion equipment for combustion of solid fuels having an inlet and outlet for gas; the said inlet is connected to the vent gas outlet of clinker cooler to supply vent gas at 130 to 230 deg C, and the said outlet of said hot air generator with a third damper connected to the waste heat recovery heat exchanger through a T- duct; the mid tap outlet of clinker cooler is joined with a fourth damper to said T- duct to mix mid tap outlet gas of temperature 350 to 400 deg C with outlet gas of hot air generator to raise the temperature of the mixed gas stream to about 450 to 500 deg C ; a first damper provided between the said vent gas outlet and inlet of the said hot air generator; a bypass provided with a second damper connected to the said vent gas outlet; the said heat exchanger enabled to generate steam to drive steam rankine cycle power plant / for generating hot thermal oil, or pressurized hot water to drive organic rankine cycle power plant.
7. A system for enhancement of waste heat recovery driven power generation by co-firing solid fuels, by increasing the temperature of vent gases of clinker cooler in the cement plant comprises a hot air generator provided with a combustion equipment for combustion of solid fuels having an inlet and outlet for gas; the said inlet is connected to the vent gas outlet of clinker cooler to supply vent gas at at 130 to 230 deg C, and the said outlet of said hot air generator with a first damper connected to the waste heat recovery heat exchanger through a T- pipe; the mid tap outlet of clinker cooler is joined with a second damper to said T-pipe to mix mid

tap outlet gas of temperature 350 to 400 deg C with outlet gas of hot air generator to raise the temperature of the gas stream to about 450 to 500 deg C ; a third damper provided between the said vent gas outlet and inlet of the said hot air generator; a bypass provided with a forth damper connected to the said vent gas outlet; the said heat exchanger enabled to generate steam/ for generating hot thermal oil, or pressurized hot water to drive organic rankine cycle power plant.
8. A system as claimed in claim 6 wherein the said combustion equipments is Pulverized Coal Burner/ Oscillating Water Cooler Grate and like.