Common use of Scrubber System Clause in Contracts

Scrubber System. The air pollution control facilities employed on Units #3 and #4 consist of a complete scrubber system, including duct work, plenums, scrubber vessels, reheaters and induced draft fans, together with infrastructures, monitoring and electrical controls and instrumentation therefore, for the purpose of removing the sulfur dioxide (SO2) and particulate matter from the flue gas. The scrubber system also includes a scrubber maintenance facility, including a machine shop and laboratory dedicated to the scrubber system and an environment monitoring laboratory for the pollution control facilities. The scrubber system utilizes the Wet Venturi Principle and consists of eight modules for each unit through which the steam generator gases from the burned coal must pass. The gases in the scrubber are contacted with finely atomized scrubber slurry. Within the stated performance of the system, fly ash particulates are removed by the slurry droplets. The sulfur dioxide reacts with the alkali contained in the slurry which results from the mixing of water, fly ash particulates, hydrated high calcium lime and hydrated dolomitic lime. A major portion of the sulfur dioxide is converted to solid sulfate compounds which are retained in the scrubber liquid and can, therefore, be piped to and deposited in an ash pond together with the particulate. After the flue gas passes through the venturi section, absorption sprays and wash trays, it is processed through a demister which removes any entrained slurry and is then reheated and discharged through the stack. The slurry system in the Units #3 and #4 scrubber system consists of recycle tanks, regenerators, agitators, pumps and pipelines. The slurry from the Units #3 and #4 scrubber system is transported to an effluent holding pond and involves the use of effluent holding tanks agitators, pumps and pipelines. A separate wash tray pond system is used to store the suspended solids collected from the wash tray system. Reclaimed water from the clear water section of these ponds is circulated back to the scrubber system. The sole purpose of the lime system is to supply the lime slurry requirements of the scrubber regeneration system. There is one lime system that serves the sixteen scrubbers for Units #3 and #4. Major components of the system include four slakers, in which calcined high calcium lime is reacted with water to produce a hydrated lime slurry, slurry transfer tanks, where the slurry is diluted with water and mixed with dry hydrated dolomitic lime, slurry feed storage tanks, where the slurry will be held for use by the regenerators as needed, hydrators, for mixing calcined dolomitic lime with water, and agitators.

Scrubber System. The air pollution control facilities employed on Units #3 function of the Scrubber System is to remove fly ash and #4 consist of a complete scrubber system, including duct work, plenums, scrubber vessels, reheaters and induced draft fans, together with infrastructures, monitoring and electrical controls and instrumentation therefore, for the purpose of removing the sulfur dioxide (SO2) and particulate matter from the flue gasgas by washing with a recycled liquor. Eight scrubber vessels are installed each at Unit 3 and 4 into which boiler combustion gases are ducted. At full load it requires that seven scrubbers operational to achieve sufficient SO2 and particulate removal to comply with environmental regulations. Since it was expected that at any given time at least one scrubber train will be down for maintenance, it was necessary to install eight scrubber trains in order to assure reliable plant operation in compliance with the law. The flue gas enters the top of each scrubber system also includes a scrubber maintenance facility, including a machine shop and laboratory dedicated to the scrubber system and an environment monitoring laboratory for the pollution control facilities. The scrubber system utilizes the Wet Venturi Principle and consists of eight modules for each unit through which the steam generator gases from the burned coal must pass. The gases vessel in the scrubber are venturi section where the gas is contacted with finely atomized scrubber slurry. Within The flue gas is adiabatically cooled and saturated by the stated performance evaporation of water from the systemscrubber slurry. In the venturi, fly ash particulates are removed by the slurry dropletsdroplets during collisions caused by the sudden changes in gas velocity. The sulfur dioxide reacts with proper gas pressure drop across the alkali contained venturi to achieve these changes in velocity is maintained by raising or lowering a xxxxx xxx located in the throat of the venturi. SO2 is also absorbed and removed by the slurry which results in the venturi. After the flue gas leaves the venturi, it passes upward through an absorption spray zone where the gas is sprayed with more scrubber slurry. These sprays remove additional SO2. Then the flue gas passes through a wash tray where it is bubbled through a stream of wash tray slurry. The main purpose of the wash tray is to remove and dilute the slurry droplets entrained in the flue gas from the mixing venturi and absorption sprays. The wash tray also removes small amounts of water, fly ash particulatesand SO2. A spray keeps the wash tray from plugging and also maintains the proper water balance in the scrubber. When the flue gas bubbles through the wash tray it produces a mist of water droplets containing some dissolved and suspended solids. This mist is removed by a mist eliminator. The mist eliminator is made up of a series of zigzag parallel plates. The mist droplets strikes these plates, cling to them, and then fall back onto the wash tray. The flue gas then leaves the scrubber vessel. At this point the flue gas has been cooled to a temperature of about 120°F and is saturated as a result of water introduced in the scrubbing process. Approximately 95% of the SO2 and over 90% of the fly ash particulates are removed. Because of the action of the scrubber in cooling and saturating the flue gas, the pressure drop across the scrubber and the moisture contents adverse conditions for the continued flow of gases to and up the stack. It is therefore necessary to reheat the gases to about 170°F and, thereafter, to restore the gas flow with ID fans. The reheater is another heat exchanger device that utilizes steam from the turbine or boiler. The heat in the reheater vaporizes any water droplets in the gas stream and at the same time raises the temperature of the gas to achieve a relative humidity below the saturation point. This improves the plum rise from the stack, reduces ground level concentrations of the emissions, and prevents the formation of acid mist that would cause corrosion and failure of equipment downstream of the scrubber. Upon leaving the reheater the flue gas enters an ID fan that serves to maintain the gas flow through the scrubber and reheater and forces it through the duct and up the stack. Units 3 and 4 are designed as balanced draft units that require forced draft fans at the furnace inlet and ID fans at the scrubber outlet. The flue gas temperature is increased to about 190°F by the compression in the fan. Each scrubber vessel is provided with one reheater and one ID fan. When the flue gas leaves the fan it enters a series of ducts where the flue gas from all of the scrubbers are combined and routed to the bottom of the stack. Each of Units 3 and 4 has its own stack that discharges the cleaned gases to the atmosphere at an elevation of 692 feet above the ground. The slurry used for the venturi and absorption sprays are taken from the recycle tank located directly below each scrubber vessel. There are two pumps for the venturi; one operates as a spare. One-half of the slurry to the venturi is injected on the tangential shelf above the venturi and the other half is sprayed on top of the plump xxx. There are also two pumps per scrubber vessel for the absorption sprays. Each pump supplies slurry to one set of sprays. The sets of sprays are located one above the other. Each set of sprays is operated independently of the other. Only one set of sprays are operated so long as the outlet SO2 emissions are below the level determined by the permits. The capability to operate two sets of sprays at once is necessary to insure that the outlet SO2 concentration will never exceed the limit permitted. The spent slurry from the venturi and absorption sprays falls to the vessel bottom and is returned to the recycle tank through downcomer pipes. The removal of fly ash and SO2 causes the buildup of suspended solid particles in the recycle tank. An agitator is used to keep these solids suspended and to promote mixing. The concentration of these suspended solids is controlled by taking a slurry bleed stream to the disposal pond where the solids settle out producing a sludge. The clear water is then returned to the recycle tank. Slurry from each recycle tank is bled to an effluent holding tank. There is one effluent holding tank for each four-scrubber vessels (two per unit). All of the effluent holding tanks discharge to one large effluent holding tank common to both units, which then discharges to the disposal pond. The alkali used for SO2 removal is a mixture of hydrated high calcium lime and hydrated dolomitic limelime (as further described in Item 3 below). A major portion This lime is added to the regenerator as a slurry. There is one regenerator per recycle tank. There is one regenerations tank feed pump per recycle tank that takes a stream of recycle slurry to the regenerator. The regenerator has an overflow line that returns regenerated slurry to the recycle tank. The purpose of the sulfur dioxide regenerators is converted to solid sulfate compounds which are retained in maintain a chemical environment different from the scrubber liquid and can, therefore, be piped to and deposited in an ash pond together with the particulate. After the flue gas passes through the venturi section, absorption sprays and wash trays, it is processed through a demister which removes any entrained slurry and is then reheated and discharged through the stack. The slurry system in the Units #3 and #4 scrubber system consists of recycle tanks, regenerators, agitators, pumps and pipelineswhich is more favorable to the chemical reactions necessary to regenerate the spent slurry after SO2 removal. The slurry from the Units #3 and #4 scrubber system There is transported to an effluent holding pond and involves the use of effluent holding tanks agitators, pumps and pipelines. A a separate wash tray pond system recycle tank from which slurry is used pumped to store the wash tray and the wash tray undersprays. There is one wash tray recycle tank for each two-scrubber vessels (four wash tray recycle tanks per unit). A bleed stream is taken from each wash tray recycle pump in order to remove the suspended solids collected from by the wash tray. This bleed stream goes to the wash tray systembleed tank (one wash tray bleed tank per unit). Reclaimed The wash tray bleed tank discharges to the wash tray pond. All wash tray recycle tanks and wash tray bleed tanks are equipped with agitators to prevent the suspended solids from settling out. The wash tray bleed tank is discharged to the wash tray pond where the suspended solids are allowed to settle out forming a sludge at the bottom of the pond. The clear water is then returned to the wash tray recycle tanks. The bottom of the mist eliminator is intermittently sprayed with blowdown water from the clear Plant’s cooling tower. This is dome to clean the mist eliminator and is also the major source of makeup water section of these ponds is circulated back to for the scrubber system. The sole purpose top of the lime system each mist eliminator is to supply the lime slurry requirements of the scrubber regeneration system. There is one lime system that serves the sixteen scrubbers also sprayed once per day for Units #3 and #4. Major components of the system include four slakers, in which calcined high calcium lime is reacted 1-1/2 minutes with water to produce a hydrated lime slurry, slurry transfer tanks, where the slurry is diluted with water and mixed with dry hydrated dolomitic lime, slurry feed storage tanks, where the slurry will be held for use by the regenerators as needed, hydrators, for mixing calcined dolomitic lime with river water, and agitators.

Scrubber System. The air pollution control facilities employed on Units #3 function of the Scrubber System is to remove fly ash and #4 consist of a complete scrubber system, including duct work, plenums, scrubber vessels, reheaters and induced draft fans, together with infrastructures, monitoring and electrical controls and instrumentation therefore, for the purpose of removing the sulfur dioxide (SO2) and particulate matter from the flue gasgas by washing with a recycled liquor. Eight scrubber vessels are installed each at Unit 3 and 4 into which boiler combustion gases are ducted. At full load it requires that seven scrubbers operational to achieve sufficient SO2 and particulate removal to comply with environmental regulations. Since it was expected that at any given time at least one scrubber train will be down for maintenance, it was necessary to install eight scrubber trains in order to assure reliable plant operation in compliance with the law. The flue gas enters the top of each scrubber system also includes a scrubber maintenance facility, including a machine shop and laboratory dedicated to the scrubber system and an environment monitoring laboratory for the pollution control facilities. The scrubber system utilizes the Wet Venturi Principle and consists of eight modules for each unit through which the steam generator gases from the burned coal must pass. The gases vessel in the scrubber are venturi section where the gas is contacted with finely atomized scrubber slurry. Within The flue gas is adiabatically cooled and saturated by the stated performance evaporation of water from the systemscrubber slurry. In the venturi, fly ash particulates are removed by the slurry dropletsdroplets during collisions caused by the sudden changes in gas velocity. The sulfur dioxide reacts with proper gas pressure drop across the alkali contained venturi to achieve these changes in velocity is maintained by raising or lowering a xxxxx xxx located in the throat of the venturi. SO2 is also absorbed and removed by the slurry which results in the venturi. After the flue gas leaves the venturi, it passes upward through an absorption spray zone where the gas is sprayed with more scrubber slurry. These sprays remove additional SO2. Then the flue gas passes through a wash tray where it is bubbled through a stream of wash tray slurry. The main purpose of the wash tray is to remove and dilute the slurry droplets entrained in the flue gas from the mixing venturi and absorption sprays. The wash tray also removes small amounts of water, fly ash particulatesand SO2. A spray keeps the wash tray from plugging and also maintains the proper water balance in the scrubber. When the flue gas bubbles through the wash tray it produces a mist of water droplets containing some dissolved and suspended solids. This mist is removed by a mist eliminator. The mist eliminator is made up of a series of zigzag parallel plates. The mist droplets strikes these plates, cling to them, and then fall back onto the wash tray. The flue gas then leaves the scrubber vessel. At this point the flue gas has been cooled to a temperature of about 120OF and is saturated as a result of water introduced in the scrubbing process. Approximately 95% of the SO2 and over 90% of the fly ash particulates are removed. Because of the action of the scrubber in cooling and saturating the flue gas, the pressure drop across the scrubber and the moisture contents adverse conditions for the continued flow of gases to and up the stack. It is therefore necessary to reheat the gases to about 170OF and, thereafter, to restore the gas flow with ID fans. The reheater is another heat exchanger device that utilizes steam from the turbine or boiler. The heat in the reheater vaporizes any water droplets in the gas stream and at the same time raises the temperature of the gas to achieve a relative humidity below the saturation point. This improves the plum rise from the stack, reduces ground level concentrations of the emissions, and prevents the formation of acid mist that would cause corrosion and failure of equipment downstream of the scrubber. Upon leaving the reheater the flue gas enters an ID fan that serves to maintain the gas flow through the scrubber and reheater and forces it through the duct and up the stack. Units 3 and 4 are designed as balanced draft units that require forced draft fans at the furnace inlet and ID fans at the scrubber outlet. The flue gas temperature is increased to about 190OF by the compression in the fan. Each scrubber vessel is provided with one reheater and one ID fan. When the flue gas leaves the fan it enters a series of ducts where the flue gas from all of the scrubbers are combined and routed to the bottom of the stack. Each of Units 3 and 4 has its own stack that discharges the cleaned gases to the atmosphere at an elevation of 692 feet above the ground. The slurry used for the venturi and absorption sprays are taken from the recycle tank located directly below each scrubber vessel. There are two pumps for the venturi; one operates as a spare. One-half of the slurry to the venturi is injected on the tangential shelf above the venturi and the other half is sprayed on top of the plump xxx. There are also two pumps per scrubber vessel for the absorption sprays. Each pump supplies slurry to one set of sprays. The sets of sprays are located one above the other. Each set of sprays is operated independently of the other. Only one set of sprays are operated so long as the outlet SO2 emissions are below the level determined by the permits. The capability to operate two sets of sprays at once is necessary to insure that the outlet SO2 concentration will never exceed the limit permitted. The spent slurry from the venturi and absorption sprays falls to the vessel bottom and is returned to the recycle tank through downcomer pipes. The removal of fly ash and SO2 causes the buildup of suspended solid particles in the recycle tank. An agitator is used to keep these solids suspended and to promote mixing. The concentration of these suspended solids is controlled by taking a slurry bleed stream to the disposal pond where the solids settle out producing a sludge. The clear water is then returned to the recycle tank. Slurry from each recycle tank is bled to an effluent holding tank. There is one effluent holding tank for each four-scrubber vessels (two per unit). All of the effluent holding tanks discharge to one large effluent holding tank common to both units, which then discharges to the disposal pond. The alkali used for SO2 removal is a mixture of hydrated high calcium lime and hydrated dolomitic limelime (as further described in Item 3 below). A major portion This lime is added to the regenerator as a slurry. There is one regenerator per recycle tank. There is one regenerations tank feed pump per recycle tank that takes a stream of recycle slurry to the regenerator. The regenerator has an overflow line that returns regenerated slurry to the recycle tank. The purpose of the sulfur dioxide regenerators is converted to solid sulfate compounds which are retained in maintain a chemical environment different from the scrubber liquid and can, therefore, be piped to and deposited in an ash pond together with the particulate. After the flue gas passes through the venturi section, absorption sprays and wash trays, it is processed through a demister which removes any entrained slurry and is then reheated and discharged through the stack. The slurry system in the Units #3 and #4 scrubber system consists of recycle tanks, regenerators, agitators, pumps and pipelineswhich is more favorable to the chemical reactions necessary to regenerate the spent slurry after SO2 removal. The slurry from the Units #3 and #4 scrubber system There is transported to an effluent holding pond and involves the use of effluent holding tanks agitators, pumps and pipelines. A a separate wash tray pond system recycle tank from which slurry is used pumped to store the wash tray and the wash tray undersprays. There is one wash tray recycle tank for each two-scrubber vessels (four wash tray recycle tanks per unit). A bleed stream is taken from each wash tray recycle pump in order to remove the suspended solids collected from by the wash tray. This bleed stream goes to the wash tray systembleed tank (one wash tray bleed tank per unit). Reclaimed The wash tray bleed tank discharges to the wash tray pond. All wash tray recycle tanks and wash tray bleed tanks are equipped with agitators to prevent the suspended solids from settling out. The wash tray bleed tank is discharged to the wash tray pond where the suspended solids are allowed to settle out forming a sludge at the bottom of the pond. The clear water is then returned to the wash tray recycle tanks. The bottom of the mist eliminator is intermittently sprayed with blowdown water from the clear Plant’s cooling tower. This is dome to clean the mist eliminator and is also the major source of makeup water section of these ponds is circulated back to for the scrubber system. The sole purpose top of the lime system each mist eliminator is to supply the lime slurry requirements of the scrubber regeneration system. There is one lime system that serves the sixteen scrubbers also sprayed once per day for Units #3 and #4. Major components of the system include four slakers, in which calcined high calcium lime is reacted 1-1/2 minutes with water to produce a hydrated lime slurry, slurry transfer tanks, where the slurry is diluted with water and mixed with dry hydrated dolomitic lime, slurry feed storage tanks, where the slurry will be held for use by the regenerators as needed, hydrators, for mixing calcined dolomitic lime with river water, and agitators.

Scrubber System. The air pollution control facilities employed on Units #3 function of the Scrubber System is to remove fly ash and #4 consist of a complete scrubber system, including duct work, plenums, scrubber vessels, reheaters and induced draft fans, together with infrastructures, monitoring and electrical controls and instrumentation therefore, for the purpose of removing the sulfur dioxide (SO2) and particulate matter from the flue gasgas by washing with a recycled liquor. Eight scrubber vessels are installed each at Unit 3 and 4 into which boiler combustion gases are ducted. At full load it requires that seven scrubbers operational to achieve sufficient SO2 and particulate removal to comply with environmental regulations. Since it was expected that at any given time at least one scrubber train will be down for maintenance, it was necessary to install eight scrubber trains in order to assure reliable plant operation in compliance with the law. The flue gas enters the top of each scrubber system also includes a scrubber maintenance facility, including a machine shop and laboratory dedicated to the scrubber system and an environment monitoring laboratory for the pollution control facilities. The scrubber system utilizes the Wet Venturi Principle and consists of eight modules for each unit through which the steam generator gases from the burned coal must pass. The gases vessel in the scrubber are venturi section where the gas is contacted with finely atomized scrubber slurry. Within The flue gas is adiabatically cooled and saturated by the stated performance evaporation of water from the systemscrubber slurry. In the venturi, fly ash particulates are removed by the slurry dropletsdroplets during collisions caused by the sudden changes in gas velocity. The sulfur dioxide reacts with proper gas pressure drop across the alkali contained venturi to achieve these changes in velocity is maintained by raising or lowering a xxxxx xxx located in the throat of the venturi. SO2 is also absorbed and removed by the slurry which results in the venturi. After the flue gas leaves the venturi, it passes upward through an absorption spray zone where the gas is sprayed with more scrubber slurry. These sprays remove additional SO2. Then the flue gas passes through a wash tray where it is bubbled through a stream of wash tray slurry. The main purpose of the wash tray is to remove and dilute the slurry droplets entrained in the flue gas from the mixing venturi and absorption sprays. The wash tray also removes small amounts of water, fly ash particulatesand SO2. A spray keeps the wash tray from plugging and also maintains the proper water balance in the scrubber. When the flue gas bubbles through the wash tray it produces a mist of water droplets containing some dissolved and suspended solids. This mist is removed by a mist eliminator. The mist eliminator is made up of a series of zigzag parallel plates. The mist droplets strikes these plates, cling to them, and then fall back onto the wash tray. The flue gas then leaves the scrubber vessel. At this point the flue gas has been cooled to a temperature of about 120OF and is saturated as a result of water introduced in the scrubbing process. Approximately 95% of the SO2 and over 90% of the fly ash particulates are removed. Because of the action of the scrubber in cooling and saturating the flue gas, the pressure drop across the scrubber and the moisture contents adverse conditions for the continued flow of gases to and up the stack. It is therefore necessary to reheat the gases to about 170OF and, thereafter, to restore the gas flow with ID fans. The reheater is another heat exchanger device that utilizes steam from the turbine or boiler. The heat in the reheater vaporizes any water droplets in the gas stream and at the same time raises the temperature of the gas to achieve a relative humidity below the saturation point. This improves the plum rise from the stack, reduces ground level concentrations of the emissions, and prevents the formation of acid mist that would cause corrosion and failure of equipment downstream of the scrubber. Upon leaving the reheater the flue gas enters an ID fan that serves to maintain the gas flow through the scrubber and reheater and forces it through the duct and up the stack. Units 3 and 4 are designed as balanced draft units that require forced draft fans at the furnace inlet and ID fans at the scrubber outlet. The flue gas temperature is increased to about 190OF by the compression in the fan. Each scrubber vessel is provided with one reheater and one ID fan. When the flue gas leaves the fan it enters a series of ducts where the flue gas from all of the scrubbers are combined and routed to the bottom of the stack. Each of Units 3 and 4 has its own stack that discharges the cleaned gases to the atmosphere at an elevation of 692 feet above the ground. The slurry used for the venturi and absorption sprays are taken from the recycle tank located directly below each scrubber vessel. There are two pumps for the venturi; one operates as a spare. One-half of the slurry to the venturi is injected on the tangential shelf above the venturi and the other half is sprayed on top of the plump xxx. There are also two pumps per scrubber vessel for the absorption sprays. Each pump supplies slurry to one set of sprays. The sets of sprays are located one above the other. Each set of sprays is operated independently of the other. Only one set of sprays are operated so long as the outlet SO2 emissions are below the level determined by the permits. The capability to operate two sets of sprays at once is necessary to insure that the outlet SO2 concentration will never exceed the limit permitted. The spent slurry from the venturi and absorption sprays falls to the vessel bottom and is returned to the recycle tank through downcomer pipes. The removal of fly ash and SO2 causes the buildup of suspended solid particles in the recycle tank. An agitator is used to keep these solids suspended and to promote mixing. The concentration of these suspended solids is controlled by taking a slurry bleed stream to the disposal pond where the solids settle out producing a sludge. The clear water is then returned to the recycle tank. Slurry from each recycle tank is bled to an effluent holding tank. There is one effluent holding tank for each four-scrubber vessels (two per unit). All of the effluent holding tanks discharge to one large effluent holding tank common to both units, which then discharges to the disposal pond. The alkali used for SO2 removal is a mixture of hydrated high calcium lime and hydrated dolomitic limelime (as further described in Item 3 below). A major portion This lime is added to the regenerator as a slurry. There is one regenerator per recycle tank. There is one regenerations tank feed pump per recycle tank that takes a stream of recycle slurry to the regenerator. The regenerator has an overflow line that returns regenerated slurry to the recycle tank. The purpose of the sulfur dioxide regenerators is converted to solid sulfate compounds which are retained in maintain a chemical environment different from the scrubber liquid and can, therefore, be piped to and deposited in an ash pond together with the particulate. After the flue gas passes through the venturi section, absorption sprays and wash trays, it is processed through a demister which removes any entrained slurry and is then reheated and discharged through the stack. The slurry system in the Units #3 and #4 scrubber system consists of recycle tanks, regenerators, agitators, pumps and pipelineswhich is more favorable to the chemical reactions necessary to regenerate the spent slurry after SO2 removal. The slurry from the Units #3 and #4 scrubber system There is transported to an effluent holding pond and involves the use of effluent holding tanks agitators, pumps and pipelines. A a separate wash tray pond system recycle tank from which slurry is used pumped to store the wash tray and the wash tray undersprays. There is one wash tray recycle tank for each two scrubber vessels (four wash tray recycle tanks per unit). A bleed stream is taken from each wash tray recycle pump in order to remove the suspended solids collected from by the wash tray. This bleed stream goes to the wash tray systembleed tank (one wash tray bleed tank per unit). Reclaimed The wash tray bleed tank discharges to the wash tray pond. All wash tray recycle tanks and wash tray bleed tanks are equipped with agitators to prevent the suspended solids from settling out. The wash tray bleed tank is discharged to the wash tray pond where the suspended solids are allowed to settle out forming a sludge at the bottom of the pond. The clear water is then returned to the wash tray recycle tanks. The bottom of the mist eliminator is intermittently sprayed with blowdown water from the clear Plant’s cooling tower. This is dome to clean the mist eliminator and is also the major source of makeup water section of these ponds is circulated back to for the scrubber system. The sole purpose top of the lime system each mist eliminator is to supply the lime slurry requirements of the scrubber regeneration system. There is one lime system that serves the sixteen scrubbers also sprayed once per day for Units #3 and #4. Major components of the system include four slakers, in which calcined high calcium lime is reacted 1-1/2 minutes with water to produce a hydrated lime slurry, slurry transfer tanks, where the slurry is diluted with water and mixed with dry hydrated dolomitic lime, slurry feed storage tanks, where the slurry will be held for use by the regenerators as needed, hydrators, for mixing calcined dolomitic lime with river water, and agitators.

Scrubber System. The air pollution control facilities employed on Units #3 function of the Scrubber System is to remove fly ash and #4 consist of a complete scrubber system, including duct work, plenums, scrubber vessels, reheaters and induced draft fans, together with infrastructures, monitoring and electrical controls and instrumentation therefore, for the purpose of removing the sulfur dioxide (SO2) and particulate matter from the flue gasgas by washing with a recycled liquor. Eight scrubber vessels are installed each at Unit 3 and 4 into which boiler combustion gases are ducted. At full load it requires that seven scrubbers operational to achieve sufficient SO2 and particulate removal to comply with environmental regulations. Since it was expected that at any given time at least one scrubber train will be down for maintenance, it was necessary to install eight scrubber trains in order to assure reliable plant operation in compliance with the law. The flue gas enters the top of each scrubber system also includes a scrubber maintenance facility, including a machine shop and laboratory dedicated to the scrubber system and an environment monitoring laboratory for the pollution control facilities. The scrubber system utilizes the Wet Venturi Principle and consists of eight modules for each unit through which the steam generator gases from the burned coal must pass. The gases vessel in the scrubber are venturi section where the gas is contacted with finely atomized scrubber slurry. Within The flue gas is adiabatically cooled and saturated by the stated performance evaporation of water from the systemscrubber slurry. In the venturi, fly ash particulates are removed by the slurry dropletsdroplets during collisions caused by the sudden changes in gas velocity. The sulfur dioxide reacts with proper gas pressure drop across the alkali contained venturi to achieve these changes in velocity is maintained by raising or lowering a xxxxx xxx located in the throat of the venturi. SO2 is also absorbed and removed by the slurry which results in the venturi. After the flue gas leaves the venturi, it passes upward through an absorption spray zone where the gas is sprayed with more scrubber slurry. These sprays remove additional SO2. Then the flue gas passes through a wash tray where it is bubbled through a stream of wash tray slurry. The main purpose of the wash tray is to remove and dilute the slurry droplets entrained in the flue gas from the mixing venturi and absorption sprays. The wash tray also removes small amounts of water, fly ash particulatesand SO2. A spray keeps the wash tray from plugging and also maintains the proper water balance in the scrubber. When the flue gas bubbles through the wash tray it produces a mist of water droplets containing some dissolved and suspended solids. This mist is removed by a mist eliminator. The mist eliminator is made up of a series of zigzag parallel plates. The mist droplets strikes these plates, cling to them, and then fall back onto the wash tray. The flue gas then leaves the scrubber vessel. At this point the flue gas has been cooled to a temperature of about 120OF and is saturated as a result of water introduced in the scrubbing process. Approximately 95% of the SO2 and over 90% of the fly ash particulates are removed. Because of the action of the scrubber in cooling and saturating the flue gas, the pressure drop across the scrubber and the moisture contents adverse conditions for the continued flow of gases to and up the stack. It is therefore necessary to reheat the gases to about 170°F and, thereafter, to restore the gas flow with ID fans. The reheater is another heat exchanger device that utilizes steam from the turbine or boiler. The heat in the reheater vaporizes any water droplets in the gas stream and at the same time raises the temperature of the gas to achieve a relative humidity below the saturation point. This improves the plum rise from the stack, reduces ground level concentrations of the emissions, and prevents the formation of acid mist that would cause corrosion and failure of equipment downstream of the scrubber. Upon leaving the reheater the flue gas enters an ID fan that serves to maintain the gas flow through the scrubber and reheater and forces it through the duct and up the stack. Units 3 and 4 are designed as balanced draft units that require forced draft fans at the furnace inlet and ID fans at the scrubber outlet. The flue gas temperature is increased to about 190°F by the compression in the fan. Each scrubber vessel is provided with one reheater and one ID fan. When the flue gas leaves the fan it enters a series of ducts where the flue gas from all of the scrubbers are combined and routed to the bottom of the stack. Each of Units 3 and 4 has its own stack that discharges the cleaned gases to the atmosphere at an elevation of 692 feet above the ground. The slurry used for the venturi and absorption sprays are taken from the recycle tank located directly below each scrubber vessel. There are two pumps for the venturi; one operates as a spare. One-half of the slurry to the venturi is injected on the tangential shelf above the venturi and the other half is sprayed on top of the plump xxx. There are also two pumps per scrubber vessel for the absorption sprays. Each pump supplies slurry to one set of sprays. The sets of sprays are located one above the other. Each set of sprays is operated independently of the other. Only one set of sprays are operated so long as the outlet SO2 emissions are below the level determined by the permits. The capability to operate two sets of sprays at once is necessary to insure that the outlet SO2 concentration will never exceed the limit permitted. The spent slurry from the venturi and absorption sprays falls to the vessel bottom and is returned to the recycle tank through downcomer pipes. The removal of fly ash and SO2 causes the buildup of suspended solid particles in the recycle tank. An agitator is used to keep these solids suspended and to promote mixing. The concentration of these suspended solids is controlled by taking a slurry bleed stream to the disposal pond where the solids settle out producing a sludge. The clear water is then returned to the recycle tank. Slurry from each recycle tank is bled to an effluent holding tank. There is one effluent holding tank for each four-scrubber vessels (two per unit). All of the effluent holding tanks discharge to one large effluent holding tank common to both units, which then discharges to the disposal pond. The alkali used for SO2 removal is a mixture of hydrated high calcium lime and hydrated dolomitic limelime (as further described in Item 3 below). A major portion This lime is added to the regenerator as a slurry. There is one regenerator per recycle tank. There is one regenerations tank feed pump per recycle tank that takes a stream of recycle slurry to the regenerator. The regenerator has an overflow line that returns regenerated slurry to the recycle tank. The purpose of the sulfur dioxide regenerators is converted to solid sulfate compounds which are retained in maintain a chemical environment different from the scrubber liquid and can, therefore, be piped to and deposited in an ash pond together with the particulate. After the flue gas passes through the venturi section, absorption sprays and wash trays, it is processed through a demister which removes any entrained slurry and is then reheated and discharged through the stack. The slurry system in the Units #3 and #4 scrubber system consists of recycle tanks, regenerators, agitators, pumps and pipelineswhich is more favorable to the chemical reactions necessary to regenerate the spent slurry after SO2 removal. The slurry from the Units #3 and #4 scrubber system There is transported to an effluent holding pond and involves the use of effluent holding tanks agitators, pumps and pipelines. A a separate wash tray pond system recycle tank from which slurry is used pumped to store the wash tray and the wash tray undersprays. There is one wash tray recycle tank for each two scrubber vessels (four wash tray recycle tanks per unit). A bleed stream is taken from each wash tray recycle pump in order to remove the suspended solids collected from by the wash tray. This bleed stream goes to the wash tray systembleed tank (one wash tray bleed tank per unit). Reclaimed The wash tray bleed tank discharges to the wash tray pond. All wash tray recycle tanks and wash tray bleed tanks are equipped with agitators to prevent the suspended solids from settling out. The wash tray bleed tank is discharged to the wash tray pond where the suspended solids are allowed to settle out forming a sludge at the bottom of the pond. The clear water is then returned to the wash tray recycle tanks. The bottom of the mist eliminator is intermittently sprayed with blowdown water from the clear Plant’s cooling tower. This is dome to clean the mist eliminator and is also the major source of makeup water section of these ponds is circulated back to for the scrubber system. The sole purpose top of the lime system each mist eliminator is to supply the lime slurry requirements of the scrubber regeneration system. There is one lime system that serves the sixteen scrubbers also sprayed once per day for Units #3 and #4. Major components of the system include four slakers, in which calcined high calcium lime is reacted 1-1/2 minutes with water to produce a hydrated lime slurry, slurry transfer tanks, where the slurry is diluted with water and mixed with dry hydrated dolomitic lime, slurry feed storage tanks, where the slurry will be held for use by the regenerators as needed, hydrators, for mixing calcined dolomitic lime with river water, and agitators.