Indian Patents. 259867:A SYSTEM FOR ENHANCEMENT OF INLET AIR MASS

Title of Invention	A SYSTEM FOR ENHANCEMENT OF INLET AIR MASS
Abstract	This invention relates to a system and apparatus for enhancement of inlet air mass for processes by progressive filtration and intermediate cooling.

Full Text	FORM-2 THE PATENT ACT, 1970 (39 of 1970) & THE PATENT RULES, 2003 PROVISIONAL SPECIFICATION (See section 10 and Rule 13) A SYSTEM FOR INLET AIR MASS ENHANCEMENT FREUDENBERG NONWOVENS INDIA PVT. LTD. An Irish Company of A-535/B, TTC Industrial Area, Mahape, Navi Mumbai-400 701, Maharashtra, India. THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION This invention relates to a system for Inlet Air Mass Enhancement. The efficiency of a gas turbine, or more correctly the overall thermal efficiency, is the ratio of mechanical work done to the heat supplied. The Carnot efficiency is defined as: ђcarnot= W/Q= (T max - T min) / T max Where: W = mechanical work Q = heat supplied Tmax= maximum temperature Tmin = minimum temperature With the Carnot formula, efficiency can be expressed as temperatures. For gas turbines, Tmax is the temperature of the hot gases leaving the combustion chamber gases and Tmin is the ambient temperature. If it is assumed that fuel is burnt at stochiometric conditions to obtain a flame temperature of 2500 K and a turbine is designed to withstand 2500 K, then the engine is working at a pressure ratio of 100, which is very high but not unreasonable assuming that the internal losses are negligible. Based on above, such a hypothetical gas turbine results in an efficiency of approximately 65%. However, in comparison, the best-performing, simple, open-cycle, single-shaft machines show an efficiency of approximately 40%. From the Carnot efficiency formula above, it is found that efficiency can be increased by increasing the temperature span between the heat source and heat sink. The heat sink cannot be made to go to a lower temperature, 2 according to the second law, but the heat-source temperature can be increased, for example by firing more fuel. Firing more fuel raises the temperature and increases the temperature span. The challenge in increasing the firing temperature is to find durable materials for use in combustor linings and turbine blades. When new materials become difficult to find, then other ways have to be found to get around the problem of overheating. Another approach for higher efficiencies is Inlet Air Cooling. Gas turbines ingest a constant volume of air regardless of the ambient air temperature. The gas turbine's power output increases as air mass flow rate increases provided other variables are kept constant. With the constant volumetric flow of a gas turbine, by increasing the air compressor inlet air density, more mass flow rate is achieved. The power produced by the turbine is nearly a linear function of air mass flow rate. If the additional mass flow from the fuel is ignored, then the ideal gas equation in respect to mass flow rate is: m = P1V1/RT1 Hence, power output is a linear inverse function of temperature. The most common technique utilized in power generation to increase mass flow is to increase the air density by lowering the inlet air temperature. There are several proven methods to cool inlet air and increase density. This invention envisages a system for inlet air cooling. Evaluation of specific solution will depend upon situation meet Utility needs. Effective management of gas turbine inlet air quantity, quality and temperature is often the most economical option to increase power, reduce heat rate, and extend component life. 3 Inlet air cooling is a technology for power augmentation but it follows an improvement in efficiency also. The efficiency improvement comes with the lowering of the Tmin temperature in the Carnot efficiency equation. The power boost achieved at a typically hot and dry site can be as much as 15%. The amount of work the compressor consumes depends on ambient conditions such as air pressure, temperature and humidity. - Gas turbines operate at a constant volume of air, - Power generated depends upon the mass flow of air. - Warm air is less dense than cold air - Higher temp, results in lower power output. In addition, warm air is much harder to compress than cold air, leaving less net available shaft energy. TYPES OF INLET AIR COOLING Inlet air cooling is sensitive to ambient conditions at a site. Choosing the correct inlet air cooling system is very site-specific. Four power augmentation technologies and their pros and cons are given below: A. Evaporative cooling Description - water flows over a corrugated surface and evaporates Advantages: 1. Mid-range installation cost 2. Small parasitic load 3. Works best when it is hottest Limitations: 1. Limited possibility to reach wet-bulb temperature 2. High pressure drop loss 3. Limited to ambient conditions 4. Water-quality dependent 5. Size restricted by media velocity 4 B. Fogging Description - Water in the form of a fine spray evaporates upstream of the compressor Advantages: 1. Low pressure drop loss 2. Minimal parasitic load 3. Low installation cost Limitations: 1. Can not go below Wet Bulb Temperature 2. Limited by ambient conditions 3. Need to use de-mineralized water 4. Always a chance of Trace elements entering Compressor 5. Downstream material may have to be upgraded (corrosion may occur) 6. Not fit for Humid environment C. Refrigeration cooling Description - a stand-alone refrigeration unit cools the inlet air achieves temperatures well below dew point. Advantages: 1. Highest power production 2. Consistent leading air temperature year-around 3. Advantageous when water is scarce 4. Independent of Water Quality 5. No Risk of erosion damage Limitations: 1. Higher parasitic load compared to Fogging Systems 2. Higher installed cost than others. 3. Large footprint compared to others 5 Therefore because of the inherent constraint of other systems, Refrigeration cooling system only can be used for cooling the inlet air below wet bulb temperatures. This invention relates to a system for inlet air cooling based on vapour absorption. In addition this invention envisages that in the process of inlet air cooling there is mass enhancement of the process air needed for the process. Clean air at a desired temperature and optimum pressure is an important requirement for several processes. Filter systems containing a bank of filters are generally used for cleaning air. The choice of filters for cleaning air is dependent upon the degree of cleanliness required and the level of contamination in the ambient, be it in the form of particulate matter or moisture. Cooling of the process air is achieved by contacting the air at a suitable stage with cooling device (fin and tube based heat exchanger) carrying chilled water. A ducting is provided for transporting the chilled clean air from the ambient to the location in the apparatus or installation where it is typically required for use as for example compressor. Another important parameter is the pressure of this process air. A chief limitation of hitherto known systems for air handling is that in the process of 6 chilling and cleaning there is a significant pressure drop i.e. a loss in pressure and consequently a loss in mass. This loss in pressure with a concomitant loss in mass causes a drop in efficiency of the turbo-machinery. This invention endeavors to provide a system whereby, not only does cool, clean air having a desired temperature and level of cleanliness reach the process installation but it also arrives there at an optimum pressure and therefore sufficient mass, efficiently and economically. With this object in mind, this invention envisages a multi stage system for air handling in which inlet air, which is typically sucked into the system, is first allowed to pass through at least one bank of pre filters, typically filters of polymeric material exemplified by polypropylene and polyethylene fiber filters of grades ranging from G2 to F6, in suitable combination, said bank of pre filters adapted to filter out particulate and other material from the air. The pre filtered air is then passed through a chilling station having at least one meandering tube carrying chilling fluid. The temperature of the pre filtered air is brought down to a designed temperature. The designed temperature can be as low as 4°C. The chilling station is typically a duct having side walls and the fin tube type heat exchanger banks at suitable pre determined locations for optimum heat exchange from the air to the chilling tubes. These chilling tubes and fins are made of heat transfer materials such as aluminum, steel, copper and alloys of metals and are coated with coating composites to control corrossion. 7 At the outlet of the chilling station in accordance with a preferred embodiment of the invention there is provided a mist eliminator which deflects the air and thus the suspended moisture in the air gets collected and start falling down due to gravity and are then drained. The pre filtered chilled demisted air is then led to the main or relatively fine filtering station where the pre filtered chilled and demisted air is channeled through a bank of fine filters having single or multiple fine filters typically in the of grades ranging from F5 to F9. Again typically of polymeric material, glass fibers, viscose or rayon fibers, cellulosic fibers and arranged in manner that effectively converging pathways are provided for the air being led through the fine filter bank. The filters could be various types including but not restricted to pocket filters with or without spacer, maxi and mini pleated filters, cartridge filters. The fibers can be coated or treated with particles , including nano composites or other material such as adhesives. The path of the air through the filter bank is precisely constructed from fine to finer to achieve the lowest pressure loss. The system is housed in a ducting that is suitably designed and internally coated to prevent corrosion by the sucked air and formations are created at suitable locations to assist forward movement of the air from the inlet towards an outlet situate at one or more desired locations in the process system where the treated air is needed. A typically output of air achieved in accordance with this invention, is clean air having particles not greater than the desired micron size at temperatures between 4 to 30 degrees Celsius where the delta P [loss in pressure] is least 8 and the mass of air entering the process installation or apparatus is enhanced by the amount that can be calculated by the below mentioned formulae (PV (PV= nrt). PlVl = P2V2 T1 T2 Thus mass of air is enhanced without significantly affecting the other parameters of the air. While considerable emphasis has been placed herein on the specific structure of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. Dated this 14th day of December 2006. Mohan Dewan Of R. K. Dewan & Co Applicants' Patent Attorneys 9

Full Text

FORM-2
THE PATENT ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
PROVISIONAL SPECIFICATION
(See section 10 and Rule 13)
A SYSTEM FOR INLET AIR MASS ENHANCEMENT
FREUDENBERG NONWOVENS INDIA PVT. LTD.
An Irish Company
of A-535/B, TTC Industrial Area, Mahape, Navi Mumbai-400 701,
Maharashtra, India.
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION

This invention relates to a system for Inlet Air Mass Enhancement.
The efficiency of a gas turbine, or more correctly the overall thermal efficiency, is the ratio of mechanical work done to the heat supplied. The Carnot efficiency is defined as:
ђcarnot= W/Q= (T max - T min) / T max
Where:
W = mechanical work Q = heat supplied
Tmax= maximum temperature Tmin = minimum temperature
With the Carnot formula, efficiency can be expressed as temperatures. For
gas turbines, Tmax is the temperature of the hot gases leaving the combustion
chamber gases and Tmin is the ambient temperature.
If it is assumed that fuel is burnt at stochiometric conditions to obtain a flame temperature of 2500 K and a turbine is designed to withstand 2500 K, then the engine is working at a pressure ratio of 100, which is very high but not unreasonable assuming that the internal losses are negligible.
Based on above, such a hypothetical gas turbine results in an efficiency of approximately 65%.
However, in comparison, the best-performing, simple, open-cycle, single-shaft machines show an efficiency of approximately 40%.
From the Carnot efficiency formula above, it is found that efficiency can be increased by increasing the temperature span between the heat source and heat sink. The heat sink cannot be made to go to a lower temperature,
2

according to the second law, but the heat-source temperature can be increased, for example by firing more fuel. Firing more fuel raises the temperature and increases the temperature span.
The challenge in increasing the firing temperature is to find durable materials for use in combustor linings and turbine blades. When new materials become difficult to find, then other ways have to be found to get around the problem of overheating.
Another approach for higher efficiencies is Inlet Air Cooling. Gas turbines ingest a constant volume of air regardless of the ambient air temperature. The gas turbine's power output increases as air mass flow rate increases provided other variables are kept constant. With the constant volumetric flow of a gas turbine, by increasing the air compressor inlet air density, more mass flow rate is achieved. The power produced by the turbine is nearly a linear function of air mass flow rate. If the additional mass flow from the fuel is ignored, then the ideal gas equation in respect to mass flow rate is:
m = P1V1/RT1
Hence, power output is a linear inverse function of temperature. The most common technique utilized in power generation to increase mass flow is to increase the air density by lowering the inlet air temperature. There are several proven methods to cool inlet air and increase density.
This invention envisages a system for inlet air cooling.
Evaluation of specific solution will depend upon situation meet Utility
needs. Effective management of gas turbine inlet air quantity, quality and
temperature is often the most economical option to increase power, reduce
heat rate, and extend component life.
3

Inlet air cooling is a technology for power augmentation but it follows an improvement in efficiency also. The efficiency improvement comes with the lowering of the Tmin temperature in the Carnot efficiency equation. The power boost achieved at a typically hot and dry site can be as much as 15%. The amount of work the compressor consumes depends on ambient conditions such as air pressure, temperature and humidity.
- Gas turbines operate at a constant volume of air,
- Power generated depends upon the mass flow of air.
- Warm air is less dense than cold air
- Higher temp, results in lower power output.
In addition, warm air is much harder to compress than cold air, leaving less net available shaft energy.
TYPES OF INLET AIR COOLING Inlet air cooling is sensitive to ambient conditions at a site. Choosing the correct inlet air cooling system is very site-specific. Four power augmentation technologies and their pros and cons are given below:
A. Evaporative cooling
Description - water flows over a corrugated surface and evaporates Advantages:
1. Mid-range installation cost
2. Small parasitic load
3. Works best when it is hottest Limitations:

1. Limited possibility to reach wet-bulb temperature
2. High pressure drop loss
3. Limited to ambient conditions
4. Water-quality dependent
5. Size restricted by media velocity
4

B. Fogging
Description - Water in the form of a fine spray evaporates upstream of the compressor
Advantages:
1. Low pressure drop loss
2. Minimal parasitic load
3. Low installation cost Limitations:

1. Can not go below Wet Bulb Temperature
2. Limited by ambient conditions
3. Need to use de-mineralized water
4. Always a chance of Trace elements entering Compressor
5. Downstream material may have to be upgraded (corrosion may occur)
6. Not fit for Humid environment
C. Refrigeration cooling
Description - a stand-alone refrigeration unit cools the inlet air achieves temperatures well below dew point. Advantages:
1. Highest power production
2. Consistent leading air temperature year-around
3. Advantageous when water is scarce
4. Independent of Water Quality
5. No Risk of erosion damage Limitations:

1. Higher parasitic load compared to Fogging Systems
2. Higher installed cost than others.
3. Large footprint compared to others
5

Therefore because of the inherent constraint of other systems, Refrigeration cooling system only can be used for cooling the inlet air below wet bulb temperatures.
This invention relates to a system for inlet air cooling based on vapour absorption.
In addition this invention envisages that in the process of inlet air cooling there is mass enhancement of the process air needed for the process.
Clean air at a desired temperature and optimum pressure is an important requirement for several processes.
Filter systems containing a bank of filters are generally used for cleaning air. The choice of filters for cleaning air is dependent upon the degree of cleanliness required and the level of contamination in the ambient, be it in the form of particulate matter or moisture.
Cooling of the process air is achieved by contacting the air at a suitable stage with cooling device (fin and tube based heat exchanger) carrying chilled water.
A ducting is provided for transporting the chilled clean air from the ambient to the location in the apparatus or installation where it is typically required for use as for example compressor.
Another important parameter is the pressure of this process air. A chief
limitation of hitherto known systems for air handling is that in the process of
6

chilling and cleaning there is a significant pressure drop i.e. a loss in pressure and consequently a loss in mass. This loss in pressure with a concomitant loss in mass causes a drop in efficiency of the turbo-machinery.
This invention endeavors to provide a system whereby, not only does cool, clean air having a desired temperature and level of cleanliness reach the process installation but it also arrives there at an optimum pressure and therefore sufficient mass, efficiently and economically.
With this object in mind, this invention envisages a multi stage system for air handling in which inlet air, which is typically sucked into the system, is first allowed to pass through at least one bank of pre filters, typically filters of polymeric material exemplified by polypropylene and polyethylene fiber filters of grades ranging from G2 to F6, in suitable combination, said bank of pre filters adapted to filter out particulate and other material from the air.
The pre filtered air is then passed through a chilling station having at least one meandering tube carrying chilling fluid. The temperature of the pre filtered air is brought down to a designed temperature. The designed temperature can be as low as 4°C.
The chilling station is typically a duct having side walls and the fin tube type heat exchanger banks at suitable pre determined locations for optimum heat exchange from the air to the chilling tubes. These chilling tubes and fins are made of heat transfer materials such as aluminum, steel, copper and alloys of metals and are coated with coating composites to control corrossion.
7

At the outlet of the chilling station in accordance with a preferred embodiment of the invention there is provided a mist eliminator which deflects the air and thus the suspended moisture in the air gets collected and start falling down due to gravity and are then drained.
The pre filtered chilled demisted air is then led to the main or relatively fine filtering station where the pre filtered chilled and demisted air is channeled through a bank of fine filters having single or multiple fine filters typically in the of grades ranging from F5 to F9. Again typically of polymeric material, glass fibers, viscose or rayon fibers, cellulosic fibers and arranged in manner that effectively converging pathways are provided for the air being led through the fine filter bank. The filters could be various types including but not restricted to pocket filters with or without spacer, maxi and mini pleated filters, cartridge filters. The fibers can be coated or treated with particles , including nano composites or other material such as adhesives. The path of the air through the filter bank is precisely constructed from fine to finer to achieve the lowest pressure loss.
The system is housed in a ducting that is suitably designed and internally coated to prevent corrosion by the sucked air and formations are created at suitable locations to assist forward movement of the air from the inlet towards an outlet situate at one or more desired locations in the process system where the treated air is needed.
A typically output of air achieved in accordance with this invention, is clean air having particles not greater than the desired micron size at temperatures between 4 to 30 degrees Celsius where the delta P [loss in pressure] is least
8

and the mass of air entering the process installation or apparatus is enhanced by the amount that can be calculated by the below mentioned formulae (PV (PV= nrt).
PlVl = P2V2
T1 T2
Thus mass of air is enhanced without significantly affecting the other parameters of the air.
While considerable emphasis has been placed herein on the specific structure of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
Dated this 14th day of December 2006.
Mohan Dewan
Of R. K. Dewan & Co
Applicants' Patent Attorneys
9

A SYSTEM FOR ENHANCEMENT OF INLET AIR MASS

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