WO2009150666A1

WO2009150666A1 - An artificial sink for removal of pollutants from flue-gases

Info

Publication number: WO2009150666A1
Application number: PCT/IN2009/000297
Authority: WO
Inventors: Ashok Kumar Datta
Original assignee: Ashok Kumar Datta
Priority date: 2008-06-13
Filing date: 2009-05-25
Publication date: 2009-12-17
Also published as: WO2009150666A9; WO2009150666A4

Abstract

This invention relates to an Artificial Sink for removal of pollutants from Flue-gases provided between main flue-gas ducts (inlet and/or outlet) ducts and short chimney(s), comprising of a plurality of modules wherein each module having two parts (Part-1 & Part-2) in which said part-1 comprising of Venturi (s) and/or cyclonic seperators for dislodging flyash connected to the main expansion chamber with a plurality of compartments for expansion/ cooling/ chemical spraying in communication with a heat-exchanger unit and at least two alkali-solution spraying chambers (each chamber represents one section with a number of cells) with at least two compartments in each section. Part-1 removes soot, fly-ash particles and SOx, while Part-2 removes NOx and CO2 prior to discharge of Flue-gases.

Description

An Artificial Sink for Removal of Pollutants from Flue-gases

FIELD OF INVENTION

This invention relates to an Artificial Sink for removal of pollutants from flue gases. The present invention is used for removal of various pollutants (fly-ash, soot particles/ SOx) from flue-gases, besides facilitating effective removal of large quantities of Carbon-Dioxide (CO2) and NOx from flue-gases, generated in fossil fuel fired industries, including power plants, prior to discharge into atmosphere via short chimney.

PRIORART

As it is known, the pollutants, such as Soot particles, Fly-ash particles and Oxides of Sulfur (SOx) have high nuisance value as well as Carbon-dioxide (CO2) and Oxides of Nitrogen (NOx), are the . major causes of greenhouse effect and global warming. These pollutants are the major constituents of flue-gases generated in the fossil fuel fired industries and power plants, but carbon-dioxide forms the largest volume, because Carbon content in fossil fuels exceeds 30%. Therefore, effective removal of CO2 from flue-gases is the major issue today, On account of this reason, this facility has been specifically termed as "an Artificial Sink for removal of Carbon- dioxide". It is also well known that most of these industries are pumping colossal amount of flue-gases globally into the atmosphere without cleansing and/ or pre- treating them via very high chimneys. Flue-gases are normally discharged into the atmosphere via lofty chimneys, which are very costly.

LIMITATIONS OF THE PRESENT STATE OF THE ART

As soon as the flue-gases are released (discharged) into the atmosphere via lofty Chimneys, the high Altitude (upper) air currents spread the contents (pollutants) of the discharged flue gases far away to a very wide area around the lofty Chimneys. Consequently, due to air-currents and mixing of atmospheric air with the discharged flue-gases, the concentration of the contents of the released flue-gases in the upper atmosphere (air) considerably reduces as compared to that in flue-gases in the ducts/chimneys prior to their discharging into the atmosphere.

Moreover, the atmosphere water vapors and rain-water not only dissolve small amount of CO₂ but they also further reduce the density of CO₂ in the upper atmosphere. This makes the removal of CO₂ from the atmosphere an impossible riddle. Thus, due to the presence of very low density of CO₂ in the upper atmosphere i.e. Natural Sink, any amount of CO₂ removal activity beyond the chimney outlet, becomes a failure. This is the major limitation of the existing systems in vogue, i.e. the present state of the art technology.

Moreover, due to cooler environment at high altitudes, the temperature of the discharged gases also reduces considerably. It further reduces the volume of the flue gases. Thus, effective removal of CO₂ from the atmosphere becomes still more difficult.

In other words, the external environmental, above the chimneys functions like a Natural Sink that can take and absorb (like a sink) within any amount of flue gases and its contents like CO₂, including other acidic fumes. Thus, the external atmosphere acts as a Natural Sink for CO₂ and other acidic fumes as well as the flue gases also get cooled.

Since discharged flue-gases also contain suspended particles (soot & fly-ash particles) and acidic fumes/gases (SOx)₁ it necessitates installation of very lojty chimneys. Presently, in order to ensure dfspersion of these contaminations over a very wide area around the chimneys after the release of flue-gases, very high chimneys (250 m to 275 m) are being installed and they are in vogue. Even then the nuisance value of the suspended particles and acidic fumes does not reduce appreciably. For instance, the large quantities of suspended particles (soot & fly-ash) gradually settle down, while acidic fumes (SOx/ CO2) discharged into the atmosphere result acid rains. They adversely affect the quality of life, vegetation and the fertility of the land all around the chimneys.

The above said adverse effect (the nuisance value) becomes more predominant and increases manifold if the chimney is not very lofty (high). This is another limitation of the present state of the art technology (i.e. discharging untreated flue-gases via chimney). Also, the capital cost of chimneys enhances exponentially as the height increases. Therefore, besides removal of the acidic fumes/gases, including CO₂, the removal of the suspended particles (ash & soot) also becomes a very essential requirement.

OBJECTS OF THE INVENTION

The primary object of the present invention is to provide "an Artificial Sink for removal of pollutants", which facilitates effective removal of large amount of carbon dioxide from flue-gases, with full control over the parameters (up to 100% volume) of flue-gases, besides overcoming disadvantages associated with the prior art. Another object of the present invention is to provide an "Artificial Sink", which effectively removes pollutants of high nuisance value (acid-fumes of SOx and suspended particles of ash & soot) from flue-gases, with full control over the parameters of flue-gases (up to 100% volume), prior to their discharge into the atmosphere.

Yet another object of the present invention is to provide a facility, (i.e. an "Artificial Sink"), which facilitates effective, removal of greenhouses gases (carbon- dioxide and NOx) from flue-gases, with full control over the parameters of flue-gases (up to 100% volume), by integration of present state of art technologies.

Further object of the present invention is to provide an "Artificial Sink", which partially or fully removes various pollutants and contaminations of high nuisance value from flue-gases, prior to removal of carbon dioxide for ensuring effective removal of carbon dioxide by present state of art technologies.

Another object of the present invention is to provide "an artificial sink for removal of carbon-dioxide", which not only facilitates effective removal of carbon- dioxide and Oxides of Nitrogen, but it also effectively removes other acid-fumes (SOx) and suspended particles of soot and ash from the flue gases prior to their discharge into the atmosphere.

Still another object of the present invention is to provide an "Artificial Sink", which effectively removes pollutants of high nuisance value (i.e. SOx and suspended particles of soot & ash) from the flue gases to dispense with lofty (250m to 275m high) chimneys, for reducing capital expenditure by installation of short (less than 100m high) chimneys, for their discharge into the atmosphere.

STATEMENT OF INVENTION

According to this invention, an "Artificial Sink for removal of carbon-dioxide" (i.e. "Artificial Sink") is to be installed between main flue-gas duct (inlet/outlet ducts) and a short chimney.

"Artificial Sink" has been designed on modular concept and each module represents an independent stream. For instance, an "Artificial Sink", for a 250 MW power plant, may comprise of Ten (10) or more modules or streams. The number and the size of modules depend upon the volume of flue-gases to be pretreated. Moreover, each module or stream of an "Artificial Sink" comprises of two (2) Parts, i.e. Part-I and Part-ll.

Part-I is an essential feature of an Artificial Sink, while Part-ll is an optional feature. Each part has two or more Sections and each section has many Cells. Also, each ceil comprises of a number of chutes for removal of effluents. Part-I ensures removal of soot/ ash particles and SOx/ CO2 from of flue-gases (up to 100% volume of flue-gases) and supplies cleansed (soot and ash free) flue-gases to the Part-I I of the "Artificial Sink" for ensuring effective removal of CO2 & NOx at Part-ll.

\n other words, Part-I eliminates the need for Lofty chimney for new industries, including power plants as well as it supplies cleansed flue-gases to Part-ll and thereby enhances the efficiency of removal of greenhouses gases at part-ll. Thus, an Artificial Sink is a versatile facilitates that would ensure effective removal of carbon-dioxides, besides other pollutants, from flue gases.

Moreover, the proven present state of the art technologies, which remove of large amount of CO2 and NOx from flue-gases, may be integrated with Part-ll of the Artificial Sink. Thus, an Artificial Sink is based on the concept of Total System Approach, because it integrates many facilities & technologies as well as it is capable of controlling the parameters of 100% volume of flue-gases for ensuring effective removal of various pollutants from flue-gases.

Sections of PART- 1

Part-1 comprises of Venturi-Section (for bleeding out flue-gases from flue-gas ducts in small quantities); Fly-ash and Soot Removal Section (i.e. a large expansion chamber with a plurality of compartments for expansion/ cooling/chemical spraying); Cooler-cum-Mixing Section; and SOx Removal section (i.e. alkali-solution spraying chambers (sections) with at least two compartments); and a Booster Fan Section. Common effluent removal facilities for disposal/recycling of effluents (i.e. soot & fly-ash particles and Sulfur compounds) at different sections are in the scope of Part-I of "Artificial Sink".

Sections of PART-II

Part-ll is an optional requirement, which can be considered as the extension of the Part-I and comprises of CO2 and NOx remdval sections as well as flue-gas discharge Section. To be specific, CO2 and NOx removal sections are optional features and they are part and parcel of Part-ll. Therefore, they are normally not considered in the scope of "Artificial Sink", but if they are to be provided, the added sections are treated as an extension of Part-I of the "Artificial Sink".

CO2 and NOx removal Sections of Part-ll are to be located between Part-I and short chimney as well as they are to be integrated with adequate number of effluent treatment units (regenerative/ recycling units) of present state of the art technologies for ensuring effective removal of CO2 and NOx as well as the compound of CO2 from effluents for further disposal/ use.

The present state of the art technologies may be integrated with the respective sections of Part4f and they are also to include specifically related regenerative/ recycling units for effluent treatment. These effluent treatment units are common for the similar sections of all the modules. Thereafter, the pollutant free flue-gases are. discharged into the atmosphere via short chimney. The Discharging Fan Section is integral to Part-ϊl.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:

Fig. 1 shows schematic flow diagram of the present invention.

Fig. 2 and 3 show conceptual layout drawing of the present invention.

SUMMARY QF THE INVENTION

The present invention is designed on modular Concept, while each module comprises of two parts and each part has specific following, major Sections, while each section comprises of a number of cells.

Major Sections in Each Module of Part-I of the Artificial Sink

1. Venturi Section

It comprises of small capacity ID Fans/ booster fans and Venturi(s), besides H2O2 spraying facility for ensuring removal of traces of NOx from hot glue gases. Cyclonic Separators with booster fans are optional requirements and are to be integrated with Main Expansion Chamber to increase the flow volume of flue-gases.

2. Fly-ash & Soot Removal Section

It comprises of a Main Expansion Chamber with a plurality of compartments for expansion, waste heat recovery pipes (an optional facility), Air-cooling and chemical spraying (dust suppression chemicals/ foam/ soap solution) activities. A common ash slurry disposal system, to cater for all lhe modules, has been envisaged for disposal of dislodged particles of soot/ fly-ash to dump yards/ ponds. 3. Cooler-cum-Mixinq Section

It comprises of a Heat Exchanger Unit (HEU), which is a water cooler. Chilled Air arid flue-gases pass through its tubes (i.e. tube-side- of the cooler) arid get thoroughly mixed. If required, air & flue-gas mix is further cooled by cOoling water flowing in the shell side.

4. SOx/ CO2 Removal Section

In this section soap solution/alkaline solution is .sprayed. A common recycling system has been envisaged to cater for all the modules.

5. Booster Fan Section

This section comprises of Booster fans (BF) or Exhaust fails (EF). The Booster Fans (0F) push flue-gases into CO2 Removal Section of Pat-H, but, If ParHl is not envisaged, partially cleansed flue-gases are discharged by Exhaust fans (pF) into atmosphere via short chimney just after Part-I.

Sections of Each Module of Part-ll of an Artificial Sink;

Part-ll comprises of CO2 and NOx Removal Sections. These are sets of addition and/ or optional Sections of {he Part-ll to be integrated with Part-I of the "Artificial Sink". Present state of the art technologies are integrated witn various sections of Part-ll of the "Artificial Sink" for ensuring effective removal of CO2 and NOx from flue-gases as well as for treatment of effluents for further disposal of CO2 gases and compounds produced dμe to C02 & NOx.

Common effluent treatment units are also envisaged for similar present state of the art technologies (i.e. proven technologies). Moreover, the last section of Part-ll is Ffue-gas Discharge Section.

The present state of the art technologies in vogue, which may be integrated with various sections of Part-ll for removing CO2 & NOx from flue-gases are given below for information only. These are optional provisions and may be provided. Accordingly, the required sections are to be provided in Part-ll of all the modules:

6. CO2 Removal Sections a) Amine Solution absorption Technology for CO2 absorption; b) Active Carbon/ Coke Beds technology for adsorption of CO2

(These technologies represent present state of the art technologies in vύgue for removal of CO2 from flue-gases.) 7. NOx Removal Sections a) Ammonia-Catalyst Technology for removal of NOx; b) Ammonia-Electronic Beam technology for removal of NOx/SOx

(These technologies represent present state of the art technologies in vogue for removal of SOx/ NOx from flue-gases.) 8. Rue-gas Discharge Section (the last section)

This section comprises of Exhaust Fans (EF) for each module and/or Common ID fans common for covering all the modules. This section ensures that cleansed/ pre-treated flue-gases that are free from the pollutants are discharged into the atmosphere via short chimney. In case of existing industries/ power plants, the existing lofty chimney is used for discharge of cleansed/ pre-treated flue-gases.

Important Components/ Items in Various Sections

1. Small capacity ID Fans

One small capacity ID fan per Venturi has been envisaged, if flue-gases are to be bled from inlet-ducts. The ID fans connect main duct of flue-gases and the venturi via small ducts corresppnding to capacities of the small capacity ID Fans. The small capacity ID Fans draw (bleed) flue-gases from the inlet-duct of the main ID fan and force the same into the venturi. The venturi releases the flue-gases at high velocity into the main expansion chamber. These ID fans do not disturb the vacuum of the main flue-gas system. Booster fans (BF) may or may not be required for venturi, if the flue-gases are to be bled from the outlet ducts. Small capacity ID fans are not envisaged at out ducts.

2. Venturi (V)

One or two venturi(s) for each module of Artificial Sink have been envisaged. The bled flue-gases are forced into the Venturi from its wider end for further pushing them into the Main Expansion Chamber. At the apex of venturi (i.e. Constriction), the flue-gases^' attain low pressure and high velocity. The released flue-gases are made to impact a target object (a drum/ plate) positioned within the first compartment of the main expansion chamber. The impact over the target object (i.e. Drum or plate) tends to reduce velocity and helps separating large percentage of ash & soot particles from the bled flue gases, prior to their further expansion and cooling. Venturi does not affect the system draft. Main Expansion Chamber

Main Expansion Chamber (MEC) normally comprises of three large compartments (C-1, C-2 & C-3). Each compartment has very large volume, in which the bled flue-gases expand as well as they are also cooled cjuite close to ambient temperature. Apex of venturi is connected to its first combartment (C- 1 ). The bled flue-gases expand very fast within very large space available within the main expansion chamber. This feature considerably reduces the velocity of bled flue-gases, which tends to separate/dislodge suspended particles (ash & sόot) that were not removed by impact.

In addition to venturi, the first compartment (C-1) also has a provision to receive additional volume of flue gases (free from soot & ash) from one or two cyclonie separators with or withdut an external waste heat recovery unit Since this provision enhances flue-gases intake capability of the Artificial Sink, main expansion chamber is also designed to cater for this provision, but it is an optional requirement.

Moreover, each compartment not only functions like an expansion chamber, but it also behaves Jike heat-exchanger and/or cool air Mixing chamber. Thus, Main Exchanger Chamber (MEC) creates similar effects as the external atmosphere i.e. the Natural Sink. a) Water & Air Cooling Facilitates to cool bled fly-ash (WAC):

Inner cooling water pipes/Coils (CC) have been envisaged in the above said compartments (C-1 and/ or C-2) for waste heat recovery from flue- gases as well as for further reducing the temperature of flue gas. But, provision of internal cooling coils (CCX i.e. cooling pipes, is an optional requirement.

Moreover, in order to have full control over temperature of flue-gases, the Cool Air Mixing (CAM) system has also been envisaged in the third compartment (C-3) of Main Expansion Chamber (MEC). This system supplies cool air (from an external source) to be mixed with the flue- gases. Also, Cooling Coils (CC) is an optional requirement. If Cooling Coils (CC), for waste heat recovery, are nor envisaged, the second compartment (C-2) can be dispensed with and/ or Cooling air may be pumped into all the compartments.

Since two cooling facilities have been envisaged to work together for controlling the temperature of the mixture of flue-gas and air, they have been termed as "Water cooling & Air Cooling Facilitates (WAC)", but air- cooling is mandatory, while water cooling facility is optional. These . cooling facilities would considerably cool the bled flue-gases and would be capable of reducing the temperature of the flue-gases and air Mixture even below 50 degree centigrade. b) Chemicals (dust suppression, soap solution, etc.)

Spraying facilitates have been envisaged within the main expansion chamber of each module of the artificial sink, for ensuring removal of large amount soot & ash particles. c) Ash removing & Soot blowing facilitates

These facilities have also been envisaged within these compartments (i.e. C-1 , C-2 & C-3) for operating at fixed intervals of time. They remove dislodged fly-ash and soot particles from the maiη expansion chamber and dispose off to small ash-dump ponds.

4. Special Heat-Exchangers (SHE)

Special Heat-Exchangers (SHE) is an optional facility. Jt is provided for waste heat recovery from the bled flue-gases. It is installed between Cyclonic_. Separator of adequate capacity and the first compartment (C-1) of the main , expansion chamber. Cyclonic Separator has been envisaged to increase flue- gas intake capability of the Artificial Sink, which is also an optional facility.

Each cyclonic separator removes suspended particle (fly-ash & soot) from the bled flue-gases, prior to feeding a heat-exchanger <SHE), which functions like a waste heat recovery Boiler. Cooler flue-gases aFe then forced into the first compartment (C-1) of the main expansion chamber. It is installed between flue-gas ducts and the Main Expansion Chamber (MEC). This feature not only increases the intake capability of the Artificial Sink, but it is also capable of meeting the emergency needs of the Artificial Sink under worst operating conditions of industry/power plant, say for example, when worst coal if fired. This unit is independent of the artificial sink, and therefore, it can be easily added if required. Adequate provisions have been made in the Artificial Sink to connect one or two such units. Therefore, connections, size and the capacity of the Artificial Sink are designed accordingly.

5. Heat Exchanger Unit (HEU)

It is provided for reducing the temperature of bled flue gases, when cool- air supply is cut-off. It also cools the gas-air mixture. Moreover, it not only mixes air and flue-gases thoroughly, but it also tends to reduce the temperature of bled flue gases, when cool-air supply is cut-off; Thus, it is an additional feature that also cools flue gas-air mixture. Heat Exchanger Unit (HEU) is a normal heat exchanger. The partially cooled flue gas-air mixture enters HEU from Main Expansion chamber (MEC). the flue gas-air mixture flows within large bores tubes of HEU, while cooling waiter flows in the shell side (outside the tubeg) in a drum_r The cooled gas-air mixture then enters the Alkali Spraying Chamber.

6. Effluent Treatment f Recycling/Regeneration) Facilities

Common effluent treatment facilities are to be providέd for treating the effluents produced in different sections/ compartments of the modules. For example, the effluent generated in all the Alkali Spray Chamber of all the modules of an Artificial Sink is to be treated in a common affluent treatment facility. This would considerably reduce the capital and operating costs.

7. Alkali-Solution Spraying Chamber (ASO

Cool flue-gases are sucked into Alkali-Solution Spraying Chamber (ASC) with the help of exhaust fans (EF)/ Booster fans (BF) installed at the end of this chamber. Within an AS chamber (ASC) a cool, alkali-water solution (say soap/caustic sόda/soda-ash/ NaOH / Ca(0H)2 solution) is sprayed directly over cooled air-flue gas mixture for cleansing purpose and removal of SOx/ CO2. Spraying of the soap/soda-ash solution, effectively eliminates acidic gases/fumes and fine suspended particles of ash and unburned Carbon particles (soot). The effluents along with the dislodged particles from the flue gases are purged out of this chamber.

AS-Chamber (ASC) is an essential facility at Part-I for removing fine suspended particles arid the acidic fumes/gases (SOx/ C 02) from flue-gases prior to removal of large quantities of CO2/ NOx from flue-gases at Part-I I and thereafter, effluents are pumped out from Part-I I into the common effluent treatment (regenerative/ recycling) units.

8. Booster Fans (BF) / ID Fans f IDF) at Part-I & H i) The booster fans (exhaust fans) push the alkali treated flue- gases (i.e. : cleansed flue-gases) into the CO2 and NOx sections of Part-ll. If Part-ll is not envisaged, the Booster Fans (BF)/ ID fans at Part-I discharge cleansed flue-gases into the atmosphere via short chimney. ii) If the Part-H is also envisaged, another set of Exhaust Fans/ common ID fans, installed at the end of Part-ll, discharges the pre-treated flue gases into the atmosphere via short chimney/ Stacks (SS).

Since Artificial Sink remove large percentage of suspended particles (Fly-ash and Soot) as well as acidic fumes/gases (SOx) from bled flue gases, it indirectly also helps in installation of short chimneys (less than 100m high) in stead of lofty chimneys (250 to 275 m high) for new power pJants/ industries. This is huge cost saving for the new power plants/industries. This financial advantage would considerably reduce the financial burden of installing modules of Part-I of the Artificial Sink.

Scope and Exlusions a) The entire system of the Artificial Sink comprises eight (8) or more modules. The modules are activated gradually and synchronized with the main Induced Draft System within inlet ducts and flue-gas discharge system at outlet ductsi of Main ID fans. The main induced draft fans, outlet ducts and Induced draft system are in scope of power plant/ industry. It is possible to run all the (8 or more) modules without affecting the Induced Draft of the system and/ or the discharge pressure of the flue-gas system.

Spraying of NaOH and/or Ca(OH)2 solutions is envisaged in the modules of part-l for removal of soot/ ash particles and large quantities of SOx, including other acidic-fumes from flue-gases. This cleansing facility is in the scope of Part-I of the artificial sink. Thus,, this facility helps in cleansing flue gases from, fine particles of soot/ ash and acidic fumes (SOx₁ CO2, etc.) prior to discharge of flue-gases via chimney or supplying cleansed flue-gases into part-H.

Cleansed flue-gases would become instrumental in facilitating effective removal of very large amount of CO₂ / NOx from Flue-gases (up to 100% volume of flue-gases) at part-ll. The Part-I is in the scope of the "Artificial Sink", while part-ll is an Optional requirement. However, if required, two or more modules and/ or sections can be easily added. b) Lime water and/ or sodium hydroxide solutions are normally used in the first section of Part-ll for removing left-over acidic fumes/ gases as well as CO₂ from flue-gases.. In addition, other present state of the art technologies in vogue may be integrated , with subsequent sections of the part-ll of the modules for removal of large quantities of CO2 and NOx. Thereafter, the remaining flue- gases are discharged into short chimney. c) The cleansed flue gases free from CO₂ are discharged into the atmosphere by exhaust fans/ small capacity common ID fans via short chimneys (or stacks). Exhaust fans/ common ID fans at Part-U are in the scope of an "Artificial Sink". . d) Effluents of the Artificial Sink (from Part-I and Part-ll) are either to be pumped to small capacity storage yards^ recycled and/ or regenerated in common effluent treatment facilities. e) Cooling Units for supplying coot water & cool Air for an "Artificial Sink" are auxiliary facilities. These auxiliary facilities are in the scope of Part-I Of the Artificial Sink. The part-f of artificial sink shall have adequate provisions for connecting these facilities.

DETAILED PESCRtPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:

Reference may be made to the accompanying drawings.

Induced Draft Fans (ID Fans)/ Booster Fans (BF) :

Flue-gases can be bled from Inlet ducts and/ or Outlet ducts of the Main Induced Draft fans (ID fans). Small capacity ID Fans draw (bleed) flue-gases from the inlet-duct of the main ID fan and push them into Venturi(s). One or two small capacity ID Fans (i.e. one for each Venturi) have been envisaged to cater for each module of an Artificial Sink, if flue-gases are to be bled from inlet-Ducts of the Main ID Fans. Small ducts connect the Venturi (s), small capacity ID Fans and Main Inlet-Duct of Flue-gases.

On the other hand, Booster fans bleed flue-gases from the outlet ducts. The Booster fans are required when the outlet pressure is inadequate. One or two small capacity booster Fans (i.e. one for each Venturi) have been envisaged to cater for each module of an Artificial Sink. ID fans (IDF) are to be provided, if flue-gases are to be bled from inlet-Ducts of the Main TD Fans. Small ducts connect Venturi(s), the booster fans and outlet ducts of flue-gases.

Each ID fan/ Booster fan forces the bled flue gases into a Venturi from its wider end. The flow is controlled (On/Off) by a set of dampers (D-1 & D-2)) Only. Each Venturi releases the flue-gases at high velocity into the main expansion chamber. These fans do not disturb the vacuum/ draft of the main flue-gas system. Venturi (V)

A venturi is a pyramid shaped vessel. The bled flue-gases are forced into the Venturi from its wider end for further pushing them into the Main Expansion Chamber (MEC) via smaller end, the. apex. At the ape* of venturi (i.e. constriction), the flue gases attain low pressure and high velocity. Therefore, H₂O₂ is sprayed within each venturi and at the apex of each venturi. High velocity/turbulence breaks H₂O₂ solution into very small Droplets, which effectively remove NOx from turbulent/expanding Flue- gases. Venturi does not disturb the system vacuum. Moreover, due to low pressure at the apex, the venturi prevents flow reversal of the bled flue-gases during the operation of the artificial-sink. Venturi is also insulated for ensuring Safety due to high temperature of the flue gases.

Main Expansion Chamber with Air & Water Cooling Facilities (WAC)

Two or three compartments (C-1/C-2/C-3) have been envisaged for the Main Expansion Chamber in each module. Each compartment has a very large volume. The cooling pipes in first two compartments (G-1: and C-2) are optional requirements. The second Compartment (C-2), which has been envisaged for the purpose of waste heat recovery, is also art optional requirement. Apex of each Venturi is connected to the first compartment (C-1) of the Main Expansion Chamber. Venturi discharges bled flue gases into the first compartment (C-1 ), wherein they hit (impact) a target (drum/ plate) at high velocity for dislodging/separating the suspended particles (soot & ash) from the flue gases. Moreover, this facility also indirectly improves the efficiency of the electrostatic Precipitator. Further expansion and cooling of the bled flue-gases takes place in the second and third compartments (C-2 & C-3). The cooling pipes envisaged in the first and second compartments (C-1 & C-2) remove heat from the hot flue gases, prior to their discharge into the third compartment (C-3) for further cooling with cold air.

After expansion in the first compartment (C-1), the flue-gases are allowed to expand further into second compartment (C-2). Besides expansion, the bled flue-gases also get cooled by the cooling water circulating in the inner pipes. Externally cooled air is pumped into the third compartment (C-3). The cold air mixes with flue-gases in this chamber and ensures controlled cooling of the air and flue-gas mixture. In fact, this provision ensures proper control over temperature of the mixture of air and flue-gases. Consequently, it is possible to reduce the temperature of flue-gases quite close to ambient temperature in the third compartment (C-3).

Thus, the complete cooling system involves "Water & Air Cooling Facilities (VVAC)". They have been provided for the Main Expansion Chamber (MEC). However, the water cooling is an optional requirements and it has to be planned in the design stage.

These cooling facilities not only cool the bled flue-gases considerably (below 50 degree centigrade), but they are also capable of reducing the volume of the air- gas. Thus, the main expansion chamber not only functions like a vast expansion ςhamber, but it also behaves IiKe a heat-exchanger, an air Mixing chamber and/or a cleansing unit. The sole purpose of cooling the flue gases in the main Expansion Chamber is to considerably reduce the volume of flue- gases. Although mixing Of cool air appears to increase the total volume of the air-gas mixture and tends to reduce the concentration of CO₂, yet, factually, the cooling effect reduces the over all volume of the air-gas mixture and indirectly increases the concentration of acidic fumes & CO₂ etc. in the air-gas mixture. This effect is alsσ-beneficial for subsequent pre-treating activities. ^'

In addition to the above Ash removing & Soot blowing facilities can also be provided for each compartment for removal of dislodged & settled fly-ash and soot particles at fixed iiitervals from these Compartments. High velocity flue-gases discharged from the Venturi are directed to hit (impinge) a target object (drum/ plate) before expanding within the compartments (C-1 , C-2 & C-3) of the main expansion chamber. The target drum may be kept cool by externally supplied cool air. Drum cooling facility is an optional provision.

The first compartment (C-1 ) can be provided with cooling pipes for recovering waste heat from hot flue-gases. If the second compartment (C-2) is provided for waste heat recovery, it also comprises of inner Cooling Pipes, in which copling water flows. These provisions further cool the flue-gases. Cool air is blown (or pushed via nozzles) into the third compartment (C-3). This feature tends to cool the flue-gases up to ambient temperature as well as it ensures full control over the temperature df the air-gas mixture. a) In the first compartment (C-1), the cooling water is not allowed to be sprayed directly over the flue gases, because it may spontaneously turn into steam due to high temperature of the bled flue-gases. This steam may tend to create back-pressure, which adversely affects the induced draft and flow of flue-gases as well as the performance of the artificial Sink. Although leakage of cooling water from the cooling pipes is not desirable, yet cooling water flowing in inner pipes ensures faster cooling of the bled flue-gases. However, cool-air is another alternative for the first compartment (C-1), if waste heat recovery at the second compartment (C-2) is not envisaged. b) In the third compartment (C-3); mixing of moist cool air with flue-gases ensures faster arid controlled cooling of Flue-gases. Also, a provision of spraying of small quantity of cool NaOH solution along with cool air in third compartments (C-3) further reduces the temperature and removes fine particles of soot and ash.

Cyclonic Separators and Special, Heat-Exchangers (3HE) for Waste Heat Recovery

A Cyclonic Separator is a pyramid shaped vessel and it is an optional requirement Provision of cyclonic separators not only increases the intake capability of the modules of Artificial Sink, but it also meets the emergency needs of the Artificial Sink under worst operating conditions of industry/power plant, say for example, when worst coal is fired. Although cyclonic separators can be added even at later date, yet their provision has to be made at the design stage of the artificial sink, because connections and the capacity of the modules of the Artificial sink have to be designed accordingly. It is possible to connect two such cyclonic separators with one module. Each cyclonic separator, does need a small capacity JD/ Booster fan. The cyclonic separator removes the suspended particles (fly-ash & soot) from the bled flue-gases by cyclonic action, prior to feeding the Special heat-exchanger (SHE), which functions like a waste heat recovery boiler.

Special heat exchanger (SHE) is an optional requirement and jt can be integrated with a Cyclonic Separator for waste heat recovery. After waste heat recovery within Special heat exchanger (SHE), cooled flue-gases are then forced into the first compartment (C-1) of the main expansion chamber. The special heat exchanger (SHE) is installed between a cyclonic separator and the Main Expansion Chamber (MEC).

Heat Exchanger unit (EHU)

From the third compartment (C-3) of the main expansion chamber, the cooled flue gases are pulled into an addition heat exchanger unit (EHU) with the help of Exhaust (booster) Farts (EF) that are installed beyond the Alkali-Solution Spraying Chamber (ASC). This unit properly mixes the cool air and flue-gases as well as it further cools flue gases, when cool air supply is cut off. Subsequently, the cooled flue gases are pulled into art Alkali-Solution Spray Chamber (ASC). HEL) has been envisaged for meeting emergency requirement of reducing the temperature of the air- gaseέ mixture close to ambieht temperature, when coo] air supply is reduced or cut off. The additional Heat-Exphanger Unit (HEU) may comprise of a chambeF with Pipes laid along the direction of flow df flue gases. The Pipes allow flow of. Flue-gasses through them, while cooling water flows out-side these pipes within the chamber.

Alkaline-Solution Spraying Chamber (ASC)

This section belongs to Part-I and it is normally used for removal of small amount of CO2 and large volume of SOx from the flue-gases. Alkalis-solutions (Ca(OH)2 and/ or NaOH) are sprayed in this section: _. Spraying of Ca(0H)2 solution in Part-1 can also be planned at design stage for removing large amount of carbon dioxide from flue-gases, if Part-H of the modules is not envisaged, jt would remove appreciable amount of carbon dioxide (CO2) from flue gases. This is an optional/ additional provision. This provision would also need slurry disposal facility.

This section, i.e. "AlkaN-Solution Spraying Chamber (ASC)" has a plurality of compartments and each compartment has a separate Alkaline Solution Spraying Unit

(ASSU). Spraying of cold water-alkali solution not only further cools the flue gases very close to ambient temperature, but it may also improve the effectiveness of subsequent reactions with CO₂ within Part-ll of the modules of the artificial sink.

Cool flue-gases are sucked into each Alkali-Solution Spraying Chamber (ASC) with the help Qf -the exhaust (booster) fans (EF) installed at the end of this chamber. Within the AS Chamber (ASC), a cool alkali-water solution (say soap Solution) is sprayed directly over the cooled flue gas & air mixture. Spraying of the soap/soda-ash solution effectively eliminates acidic gases/fumes (SOx) as well as fine suspended particles of fly-ash and unburnt carbon (soot). Thus, this section also cleanses the flue-gases. The effluents along with the dislodged particles from the flue gases are purged out of this chamber of further treatment (recycling/ regeneration) in a common effluent treatmenHacility.

Each compartment has a zig-zag path, which increases the length of the flow path for air-gases mixture. Consequently, it increases the period of the reaction of acidic fumes with alkali-water solution as well as it increases the duration for removal of suspended particles from the air-gas mixture. Thus, zig-zag path not only improves the effect of acid-alkali- reactions, but it also ensures optimum removal of almost all the suspended particles by spraying process of Alkali-water Solution.

Hence, ASC is an essential requirement, because it helps in removal of large amount of the acidic fumes/gases (SOx) and partial removal of carbon dioxide (CO2 ) from the flue-gases as well as it also ensures effective removal, of the finer particles of ash and soot, prior to their discharge into short chimney and/ or Part-H Qf the modules for further pretreatment processes. In new power plants, this feature reduces hgge capital investment by elimination of lofty (250 to 270 m high) chimney, because sjiort chimney meets the requirement.

Part-H of Each Module of Artificial Sink (An Optional Requirement)

Part-H comprises of CO2 and NOx Removal Sections. These are sets of addition and/ or optional Sections and they are to be integrated with Part-l of the "Artificial Sink". Present state of the art technologies can be integrated with various sections of Part-H of the "Artificial Sink" for ensuring effective removal of CO2 and/ or NOx from flue-gases as well as for treatment of the respective^' effluents for further disposal of CO2 gases and compounds produced due to CO2 & NOx. Common effluent treatment units are envisaged for similar technologies. (Note: A brief introduction of present state of the art technologies, which may be integrated with Part- II, is also given below)

6. Carbon Dioxide (CO2) Removal Sections a) Calcium Hydroxide Solution is sprayed in this section. Also, a common slurry disposal system has been envisaged to remove slurry from all the modules for its disposal to dump yards (pond). In this section Amine Solution is sprayed, which absorbs CO2. A common Regenerative unit for effluent treatment has been envisaged that separates Carbon dioxide gas from flue-gases and further disposal of CO2 gas is ensured after compression/cooling. It is a common facility that caters for all the Modules. (It is a present state of the art technology.) b) . In this section, Active carbon/ coke beds have been envisaged for adsorption (i.e. removal) of Carbon Dioxide from flue-gases. A common Regenerative unit for effluent treatment has been envisaged for separating carbon dioxide gas from flue-gases and for further disposal of CO2 gas after compression/cooling. It is a common facility that caters for all the Modules. (It is a present state of the art technology.) 7. Nitrogen Oxides (NOx) Removal Sectionfs) a) In this section Ammonia is sprayed over flue-gases and catalyst helps in removal of NOx from flue-gases at low temperature. (It is a present state of the art technology.) b) In this section Ammonia & Electronic beam are used for removing NOx from flue+gases. (U is a present state of the art technology.)

8. Flue-gas Discharge Section

This section comprises of booster Fans for each module and/ or a Common ID fans common for covering all the modules. This section ensures that the pre- treated flue-gases that are free from the pollμtants are discharged into the atmosphere vig short chimney.

Small capacity Booster Fans/ Exhaust Fans f EF)

Small capacity Booster Fans (BF)/ Exhaust Fans (EF) have been envisaged for boosting up the flow of flue-gases and for maintaining proper flow of air-gas mixture within the modules of the part-l of the Artificial SiRk. The Booster fans/- Exhaust fans are installed after AS Chambers (ASC) at the end of Part-I and beginning of Part-ll. They generate adequate pressure for discharging the flue-gases either to a short chimney or into the first section of Part-ll.

The exhaust Fans/ booster fans pull out cooled air-gas mixture from all the compartments (C-1, C-2 & C-3) of the Main Expansion Chamber (MEC) as well as from AS Chambers (AS.C). Finally, they discharge the cleansed air-gases mixture into the subsequent sections of Part-ll or into the short chimney, if Part-ll is not provided.

Working Principle of Artificial Sink i) Small capacity ID Fans (IDF) have been envisaged for bleeding the flue- gases from inlet ducts, while Booster fans (BF) have been envisaged for bleeding the flue-gases from the outlet (exhaust) ducts of the main ID-Fans of the power plants/ industries. Theses fans bleed flue-gases from the ducts and force the bled flue-gases into Venturi(s).

The ID Fans become essential if flue-gases are drawn form inlet-ducts. However, when the flue-gases are bled from outlet duct, the Booster fans may or may not be required as the Main ID Fans generate enough pressure to force the flue-gases into the Venturi(s), because the requirement of Booster fans depends upon pressure availability. Dampers (D-1 & D-2) open or close the flow passages of the connecting ducts. ii) Each Venturi (V) discharges the bled flue-gases directly into the first compartment (C-1 ) of the Main Expansion Chamber (MEG). The flue-gases are discharged at high velocity and are directed to hit (impinge) a drum (D) or a plate within the first . compartment (C-1) for separation of fly-ash and soot particles from bled flue-gases. If cyclonic separators, are also provided, with or without Special Heat Exchanger (SHE) units, they also discharge the b|ed flue- gases at lower velocities into the first compartment (C-1). Thereafter, the flue- gases are allowed to expand and get cooled m a controlled manner. iii) The cooling water pipes, within the first two compartments (G-1 & C-2), recover waste heat from the hot flue-gases during gradual expansion. Externally cooled cool air is supplied through a number of wide nozzles at high velocity into the third compartment (C-3). Both the externally cooled air and the flue-gases expand and get mixed within the third compartment (C-3). Mixing cool air ensures cooling in a controlled manner.

Thus, water/ air cooling facilities (WAC) provided in the Main Expansion Chamber (MEC) cool the air-gas mixture considerably. Thereafter, the partly, mixed air-gas mixture enters the Heat-Exchanger Unit (HEU). The cool-air and flue-gases pass through the tubes of HEU, wherein they get thoroughly mixed. Moreover, if further cooling js required, copjing water is supplied in the shell side of HEU. This cooling is required only when cool air supply is cutoff. a) The . large expansion space results in great amount of reduction of velocity and concentration of acidic fumes/gases and CO₂ in flue-gases. On account of the availability of targe space (volume) for expansion, heavy suspended particles of ash &.soot also get separated from the flue gases. Consequently, the dislodged particles (fly-ash & soot) settle down on the floor of the first and second coπipartment (C-1 & C-2) of MEC, which are periodically removed by automatic system for cleansing these compartments. b) In addition to the above, the provision of spraying of chemicals (dust suppression solution, foam, NaOH solution, etc.) within these compartments also removes large quantity of finer particles (ash & soot) as well as small amount of acidic fumes/gases from the bled flue-gases. Moreover, low temperature of air-gas mixture reduces the volume of air- gas mixture, increases the concentration level of acidic fumes (SOx,

. NOx, CO₂, etc) and improves the working efficiency of the subsequent sections of the modules. iv) Finally, properly cooled air-gas mixture is pulled into Alkafϊ-Soiution spraying Chamber (ASC) via Heat Exchanger unit (HEU) by the exhaust fans (EF). In this chamber, the alkali-water solution or solutions are continuously sprayed by no≥zles. The Alkali-water solution reacts with the acidic fumes/gases (SOx and CO2). These reactions remove the acidic fumes/ gases from the flue gases. Due to spraying action, the left-over fine suspended particles of soot & ash are also removed. Thus, AS chamber further cleanses the air-gas mixture from the acidic gases and fine suspended particles. ASC chamber may have three or four compartments with baffle-partitions, which ensure proper chemrcal reactions. v) Thereafter, the Exhaust Fans connected to AS Chamber push the cool air-gas mixture into the short chimney (SC) and/or info the sections of Part-ll of the modules, wherein SOx, NOx and CO2 etc. are removed in large quantities from the cool air-gas mixture. The proven (the present state of the art technologies) technologies are integrated with various sections of the part-ll of each module. Also, common regenerative/ recycling units have been envisaged for meeting the needs of each technology. Another set of exhaust fans (EF) or common ID Fans (installed after part-ll) disςharges the remaining air-gas mixture into the atmosphere via small stacks or via a short chimney. .

Part-I of an "Artificial Sink", which effectively removes acid-fumes (SOx/Cθ2) and suspended particles of soot and fly-ash from 100% volume of flue-gases, may dispense with lofty (250m or more) chimneys in new power plants/ industries and may require installation of short (less than 10Qm) chimneys, for discharging of cleansed and/ or treated flue-gases into the atmosphere.

The Artificial Sink not only ensures full control over the parameters (i.e. temperature, flow-volume, velocity, concentration level, etc.) of the entire flue-gases (i.e. 100% volume of flue-gases), but it also facilitates effective removal of carbon- dioxide, other acidic-fumes/gases and suspended particles (ash & soot) from the flue- gases generated in fossil fuel fired industries/power plants. Moreover, it is also capable of recovering waste heat from flue-gases.

It is to be noted that the present invention is susceptible to modifications, adaptations and changes- by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims.

Claims

I CLAIM:

1. An artificial sink, which is installed between main flue-gas ducts (inlet and/ or outlet ducts) and short chimney(s), comprises of 8 or more modules for controlling the parameters of 100% volume of flue-gases, while each module has two parts (Part-l & Part-ll) and the artificial Sink effectively removes pollutants with high nuisance value (i.e. soot, fly-ash, SOx, etc.) in different sections of its Part-l and facilitates effective removal of large quantities of greenhouse gases (i.e. NOx and CO2) in different sections of its Part-ll from 100% volume of flue-gases generated in fossil fuel fired industries, including power plants, prior tb discharge into the atmosphere via chimneys as well as Part-l comprises of Vehturi(s) and/ or Cyclonic separators (to dislodge fly-ash), which are connected to the main expansion chamber with a plurality of compartments for expansion/cooling/ chemical spraying activities in communication with a heat exchanger unit^" and at least two alkali-solution - spraying chambers (each chamber represents one section with a numbers of cells) with at least two compartments in each section, while the proven technologies (the present state of the art technologies), for removal of large quantities of NOx & CO2, are integrated with Part-ll.

2. Each module of an artificial sink as claimed in claim 1 comprises of at least two small capacity ID Fans (IDF) in case flue-gases are to be drawn from the inlet duct of the main ID fans to be forced into respective venturi and if the flue-gases are to be drawn from the outlet ducts, the Booster Fans (BF) may to be provided instead of ID-Fans, if required.

3. Each module of an artificial sink as claimed in claim 1 or 2 comprises of a plurality of Exhaust fans (EF) next to the alkali-solution spraying chambers (ASC) for forcing the treated/ cleansed flue-gases into Part-ll and/ or short chimney.

4. Each module of an artificial sink as claimed in any of the preceding claims wherein the said ID Fans/ Booster Fans connect main duct of flue-gases and venturi via small ducts.

5. Each module of an artificial sink as claimed in any of the preceding claims wherein the first compartment (C-1 ) of the said main expansion chamber is provided with a target object to be hit by flue gases released from the said venturi.

6. Each module of an artificial sink as claimed in any of the preceding claims wherein a special heat exchanger (SHE) with a cyclonic-separator may be provided.

7. Each module of an artificial sink as claimed in any of the preceding claims wherein a special heat exchanger (SHE), a waste heat recovery unit, may be connected to the said first compartment (C-1) of the main expansion chamber, while other its end is to be connected to a cyclonic separator (CS) having a Booster fan (BF).

8. Each module of an artificial sink as claimed in any of the preceding claims wherein a plurality of inner cooling water pipes/ coils (CC) may be provided in the said first two compartments (C-1 & C-2) for waste heat recovery and for further reducing the temperature of the flue gases.

9. Each module of an artificial sink as claimed in any of the preceding claims wherein a cool-air mixing (CAM) system is to be provided in the third compartment (C-3) of the said main expansion chamber.

10. Each module of an artificial sink as claimed in any of the preceding claims wherein the chutes provided are to be connected to common effluent treatment systems for treating the effluents produced from different compartments and/ or sections of modules of Part-I and Part-ll.

11. Part-I of each module of an artificial sink as claimed in any of the preceding claims wherein within the said Alkali-Solution Spraying chamber (ASC), a cool alkali-water solution (soap/caustic/soda-ash solution/lime water) is sprayed directly over cooled air-flue gas mixture.

12. Each module of an artificial sink as claimed in any of the preceding claims comprises of a plurality of exhaust fans or common small capacity ID Fans for the entire artificial sink at the end of Part-I and/ or Part-ll for discharging the cleansed or pre-treated flue gases into atmosphere via short chimney or independent stacks.

13. Each module of an artificial sink as claimed . in any of the preceding claims comprises of Part-I and Part-ll, while each part comprises of two or more sections and each section comprises of a large number of cells, each with effluent removal chutes as well as Part-ll may be provided in case greenhouse gases (NOx and / or CO2) are to be removed.

14. Part-ll of each module of an artificial sink as claimed in any of the preceding claims comprises of two or more sections, which may be integrated with the . proven technologies, i.e. present state- of the - art technologies, while, each proven technology may be complete with common effluent recycling and/or regenerative units.

15. Part-I of an "Artificial Sink", which effectively removes acid-fumes (SOx/CO2) and suspended particles of soot and ash from the 100% volume flue gases, as claimed in any of the preceding claims, may dispense with lofty (250m or more) chimneys in- new power plants/ industries and may require installation of short (less than 100m) chimneys, for discharge of cleansed and/ or treated flue-gases into the atmosphere.

16. An artificial sink for removal of pollutants from flue gases, and/ or effective removal of nitrogen-oxides (NOx) and carbon-dioxide (CO2) substantially as herein described with reference to accompanying drawings.