FORM - 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENT RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10 AND RULE 13)
"A NEW CONTROL SYSTEM FOR MAXIMIZATION OF HEAT REUTILIZATION AND HEAT RECOVERY IN CEMENT PLANT TO SIMULTANEOUSLY ACHIEVE BEST PRODUCTIVITY AND QUALITY OF CLINKER-TRANSPARENT ENE.RGY SYSTEMS PRIVATE LIMITED AN INDIAN COMPANY, "PUSHPA HEIGHTS", 1ST FLOOR, BIBWEWADI CORNER, PUNE SATARA ROAD, PUNE- 411 037, MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION
The present invention relates to a novel design of control system for maximization of heat reutilization and heat recovery in cement plant to ε 'multaneously achieve best productivity and quality of cement clinker.
PRIOR ART
Cement making process involves several energy intensive unit operations such as size reduction, feed drying, coal drying and pyro-processing. Various steps have been taken by cement industry to improve energy utilization in cement plant. Dried and crushed raw materials are fed to preheater cyclones to heat them up to 1100 deg C. The last stage in preheater cyclone assembly is calciner where 70% of the total coal is combusted to carry out decarbonation of limestone. The hot gases generated in this process travel through preheater cyclones to heat the feed and then they are exhausted at 280 to 320 deg C. The exhaust gases are cooled to 150 to 200 deg C in gas conditioning tower and then they are passed through electrostatic precipitator or bag filter to remove dust particles before finally exhausting to atmosphere. In some cement plants the heat energy in these gases is used for drying ccal in coal mill, before they pass through electrostatic precipitator of bag filter. The decarbonated mass in calciner is fed to rotary kiln for clinkerization process. This process takes place at 1400 to 1450 deg C. Remaining 30% of the coal is combusted in rotary kiln to maintain the desired temperature. The clinker at 1400 deg C is cooled to 100 to 150 deg C in clinker cooler by blowing atmospheric air over it with the help of series of forced draft fans. This cooler could be reciprocating grate cooler or rotary cooler or planetary cooler. The hot air exhausted by rotary cooler or planetary cooler is supplied to rotary kiln as combustion air for burning coal. In cement plants having reciprocating grate coolers the highest temperature air at around 1100 to 1300 deg C is supplied to rotary kiln as secondary air for combustion of coal. The air of relatively lower temperature of about 800 to 950 deg C is tapped as tertiary air from grate type clinker cooler and it is supplied to calciner for combustion of coal. The remaining exhaust gases of still lower temperature of about 260 to 280 deg C are cleaned in Electrostatic precipitator or bag filter before they are exhausted to atmosphere. The waste heat recovery based power generation systems (ref. Indian Patent no. 197769 and Indian Patent no. 197768) is installed in cement plants on preheater exhaust gases, clinker cooler exhaust gases or on the gases from midtap taken on clinker cooler after fulfilling all other air requirements of cement process. The location of midtap is engineered depending

on the temperature of clinker, the hot air requirements of the cement plant and the temperature of cooler exhaust gas. Booster fan is installed at the outlet of this waste heat recovery system to overcome the additional pressure drop in the case where no margin is available in the existing ID fan at outlet of clinker cooler. The existing cement plants have following control system to control the operations mentioned above.
All the controls on process air in existing cement plants are based on indirect
measurement
Coal Feed Rate to Rotary Kiln is fixed based on Kiln operating capacity. However kiln
temperature profile is measured from quality control point of view.
Coal Feed Rate to Calciner is fixed based on kiln operating capacity
Coal Feed Rate to Coal Mill is based on coal mill operating capacity
Hood Draft Pressure at single point location on cooler is controlled by cooler exhaust ID
fan or damper and Preheater exhaust ID Fan.
Hood Draft Pressure is only measured at several point locations on the clinker cooler.
Tertiary air flow is fixed on Air fuel ratio control based on coal flowrate to calciner.
Typically, all the air supplied by first fan at the clinker inlet side of cooler is supplied to rotary kiln for combustion of coal irrespective of how much is required. Typically, the air supplied by the next two successive fans is supplied to calciner. The part of the remaining air at lower temperatures is also supplied to coal mill. It is likely, that due to insufficient control over cooler air distribution and temperature, the coal mill can suffer from fire hazards. The air available after fulfilling these requirements is available for waste heat recovery based power generation system. Due to insufficient controls present of air aupplied by cooler to various cement plant operations, there are limitations in designing the control system for air supply to waste heat recovery boiler. Any fluctuations in temperature and quantity of air supplied to waste heat recovery boiler resulting from insufficient control over clinker cooler air distribution affect the performance of boiler.
LIMITATIONS OF PRIOR ART
1. Initially developed control systems for cement plant were designed from the point of view of rejecting maximum heat after fulfilling the energy requirements of process. Therefore, the necessary features from the point of view of performance

of a waste heat recovery based power generation system in a cement plant have not been provided in the existing control sys'em of cement plant !. Manual monitoring of flow rates and temperature of secondary air, tertiary air, air for coal mill has limitations in optimizing heat utilization of cement plant. Due to this only the residual heat available in the system Is made available for driving waste heat recovery based power generation plant.
3. The fuel consumption per unit of clinker produced is also higher as there is no precise control on supply of fuel based on the process requirements
4. Due to insufficient control over cooler air distribution, the heat rejections are also higher which adversely affect
PRESENT SCENARIO AND NEED FOR INVENTION
The waste heat recovery based power generation systems (ref. Indian Patent no. 197769 and Indian Patent no. 197768) is installed in cement plants on preheater exhaust gases and clinker cooler exhaust gases. The performance of this system depends on the quantity and temperature of trie exhaust gases. Due to insufficient control system in cement plants, the temperature and quantity of gases available for waste heat recovery based power generation plant keeps fluctuating leading to fluctuations in the performance of the waste heat recovery system. Due to insufficient control system, the heat utilization in cement plant is not optimum. Secondly, clinker quenching process to achieve best quality clinker is not being controlled in the present cement plants. Therefore, a novel control system is needed to achieve maximization of heat recovery and heat reutilization in cement plant simultaneously achieving the bejt quality and productivity and energy efficiency.
OBJECT OF THE PRESENT INVENTION
The present invention relates to a novel design of control system for maximization of heat
reutilization and heat recovery in cement plant to simultaneously achieve best
productivity, quality of cement clinker and energy efficiency.
Yet another object of the present invention is to eliminate the drawbacks and limitations of
the prior art.
One more object of the present invention is to develop a system relating to the direct and
independent controls over limiting parameters in cement plant.

BRIEF DESCRIPTION OF SCHEMATIC DRAWINGS
Fig.1 & 2 are the Control Logic mechanisms in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Now referring to Fig.1 and 2,the new control system in the present invention particularly relates to the direct and independent controls over limiting parameters in cement plant. The novel control system in the present invention can be implemented in a cement plant comprising of preheater cyclones of four, five or six stages, rotary kiln with single or multichannel burner, and clinker cooler of any of the prevailing designs of coolers. More particularly the novel control system relates to the control of following parameters based on several measurements described further:
1. Hoof Draft pressure of the cooler
2. FD fan air flowrate controls on cooler to fulfill requirements of secondary air, tertiary air, air for coal mill and air for WHRB.
3. Coal feeding rate controls on rotary kiln calciner and coal mill
4. Temperature controls on air supplied to waste heat recovery based power generation system and coal mill.
Casel:
A novel control system for cement plant, as described in fig 1., comprising of four, five or six stage preheater cyclone tower, rotary kiln with single or multichannel burner, grate type clinker cooler, waste heat recovery based power generation system on preheater exhaust gases and mid-tapped gases from clinker cooler.
The control procedure is as mentioned below.
Coal Feed Rate (6) to Rotary Kiln (34) to be controlled on Kiln Temperature (7)
Coal Feed Rate (3) to Calcine*- (32) to be controlled on calciner feed outlet temperature
(8)
Coal Feed Rate to Coal Mill (17) to be controlled on coal mill (38) outlet gas temperature
(22)

Hood Draft Pressure (9) to be controlled on ID Fan (1) rpm
Hood Draft Pressure (11) to be controlled on ID Fan (27) rpm
Hood Draft Pressure (20) to be controlled on ID Damper (29)
Hood Draft Pressure (23) to be controlled on ID Fan (30)
Hood draft pressures (9), (11), (20) and (23) all have identical set points
Tertiary air flow (5) to be controlled on Air fuel ratio control based on coal flowrate (3)
FD Fan (10) Flow rate (48) to be controlled on coal firing rate (6)
FD Fan (12) Flow rate (49) to be controlled on coal firing rate (3)
FD Fan (13) Flow rate (50) to be controlled on coal mill inlet gas temperature (14)
FD Fan (16) and (21) Flow rate (51) and (52) respectively to be controlled on WHRB (40)
gas inlet temperature (18)
FD Fan (24) and (25) Flow rate (53) and (54) respectively to be controlled on Clinker
discharge temperature (26)
Boiler (40) inlet temperature (18) to be controlled on FD fans (16) and (21) air flow rate
(51) (52), damper (15) and damper (19)
Coal mill (38) inlet air temperature (14) to be controlled on FD fan (12) air flowrate (50)
and damper (47)
Case2:
A novel control system for cement plant, as described in fig 2., comprising of four, five or six stage preheater cyclone tower, rotary kiln with single or multichannel burner, grate type clinker cooler, waste heat recovery based power generation system with booster fan on preheater exhaust gases and mid-tapped gases from clinker cooler.
The control procedure is as mentioned below.
Coal Feed Rate (6) to Rotary Kiln (35) to be controlled on Kiln Temperature (7)
Coal Feed Rate (3) to Calciner (33) to be controlled on calciner feed outlet temperature
(8)
Coal Feed Rate to Coal Mill (17) to be controlled on coal mill (40) outlet gas temperature
(22)
Hood Draft Pressure (9) to be controlled on ID Fan (1) Hood Draft Pressure (11) to be controlled on ID Fan (27) Hood Draft Pressure (20) to be controlled on ID Fan (30)

Hood Draft Pressure (23) to be controlled on ID Fan (31)
Hood draft pressures (9), (11), (20) and (23) all have identical set points
Tertiary air flow (5) to be controlled on Air fuel ratio control based on coal flow rate (3)
FD Fan (10) Flow rate (48) to be controlled on coa1 firing rate (6)
FD Fan (12) Flow rate (49) to be controlled on coal firing rate (3)
FD Fan (13) Flow rate (50) to be controlled on coal mill inlet gas temperature (14)
FD Fan (16) and (21) Flow rate (51) and (52) respectively to be controlled on WHRB (41)
gas inlet temperature (18)
FD Fan (24) and (25) Flow rate (53) and (54) respectively to be controlled on Clinker
discharge temperature (26)
Boiler (41) inlet temperature (18) to be controlled on FD fan (16) and (21) air flow rate (51) and (52) respectively, damper (15) and damper (19)
Coal mill (40) inlet air temperature (14) to be controlled on FD fan (13) air flowrate (50) and damper (55)
ADVANTAGES OVER THE PRIOR ART WHICH INCLUDE AS FOLLOWING:
1. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant to simultaneously achieve best quality of clinker consistently.
2. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant to simultaneously increase productivity of cement plant.
3. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant to simultaneously achieve optimum fuel consumption of continuous basis
4. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant that improves visibility of process for better control
5. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant that advantageously incorporates the patented technology of waste heat recovery

based power generation systems for cement plants (Ref. Indian Patent no. 197769 and Indian Patent no. 197768)
6. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant that can be customized to make it suitable for existing cement plan as well as a green field project.
7. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant that can be customized to incorporate control of all the process equipments and their energy requirements in cement plant having any of the prevailing designs including the designs of modified clinker coolers (Ref. application numbers 2805/MUM/2009 and 2806/MUM/2009)
8. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant that reduces the electricity consumption of cement plant through improved controls over cooler and all the ID / FD fans.
9. The present invention relates to the design of a novel control system for maximization of heat reutilization and heat recovery in cement plant that improves the performance of waste heat recovery based power generation system as the fluctuations in temperature and flowrate of air supplied to this system are reduced.
10. The present invention relates to the design of a novel control system for maximization of hest reutilization and heat recovery in cement plant that overcomes all the drawbacks of the prior art.

WE CLAIM:-
1. A new control system and method for maximization of heat reutilization and heat
recovery in cement plant to simultaneously achieve optimum productively and
quality of clinker; said method comprising
i) Controlling the coal feeding rate;
ii) Controlling hood draft pressure on ID fan and damper;
iii) Controlling FD fan air flow rate on cooler thereby fulfilling requirements of
secondary air, tertiary air, air for coal mill and air for WHRB and iv) Controlling temperature of air supplied to waste heat recovery based power
generation system and coal mill thereby achieving the maximization of heat
reutilization and heat recovery in cement plant to simultaneously achieve
optimum productively and quality of clinker.
2. A method as claimed in claim 1 wherein the said coal feeding rate to rotary kiln, coal feeding rate to calciner and coal feeding rate to coal mill is controlled on kiln temperature, calciner feed outlet temperature and coal mill outlet gas temperature respectively.
3. A method as claimed in claims 1 and 2 above further comprises optimizing FD fan flow rate depending upon coal firing rate, coal mill inlet gas temperature, WHRB gas inlet temperature, clinker discharge temperature, boiler inlet temperature, boiler inlet temperature and coal mill inlet temperature.
4. A new control system for maximization of heat reutilization and heat recovery in cement plant to simultaneously achieve optimum productively and quality of clinker; said system comprising of four, five or six stage preheater cyclone tower; rotary kiln with single or multichanrel burner; grate type clinker cooler; WHRB as described in patent no. 197769 and 197768 or any other on preheater exhaust gases and midtapped gases from said clinker cooler characterize in that there are provided controls for controlling i) the coal feeding rate; ii) hood draft pressure on ID fan and ID damper; iii) FD fan air flow rate on cooler thereby fulfilling requirements of

secondary air, tertiary air, air for coal mill and air for WHRB; and iv) temperature on air supplied to waste heat recovery based power generation system and coal mill.
5. A new control system and method for maximization of heat reutilization and heat recovery in cement plant to simultaneously achieve optimum productively and quality of clinker as claimed in claim 1 to 4 above wherein controls are achieved through direct and independent measurement of limiting parameters.
6. A new control system and method for maximization of heat reutilization and heat recovery in cement plant to simultaneously achieve optimum productively and quality of clinker as claimed in claim 1 to 5 above and as herein described with reference to the drawings of the accompanying specification.