Title of Invention	STEAM GENERATION PLANT
Abstract	The invention relates to a steam generation plant, comprising a steam generator (1) with a combustion chamber (8), an evaporator, a superheater (9), an intermediate superheater (12), a condenset (14), a feed water preheater (16, 19, 19') regeneratively heated by steam, a steam turbine set (2) with a high-pressure section (4), a medium pressure section (5) and a low-pressure section (6), a flue gas line (22), connected to the combustion chamber (8), an air supply line (21), for the supply of combustion air to the burner in the combustion chamber (8) and an air preheater (3) with flue gas and combustion air passing therethrough. An air line (23) branches off from the air supply line (21) downstream of the air preheater (3) in said steam generation plant and supplies an air-fractionation unit (25). Air-coolers (34,35) are arranged in the air line (23) through which the condensate or feed water from the condensate/feed water circuit from the steam generator (1) flows. The oxygen output from the air fractionation unit (25) is connected to the burner of the combustion chamber (8) by means of an oxygen line (26).

Title of Invention

STEAM GENERATION PLANT

Abstract

The invention relates to a steam generation plant, comprising a steam generator (1) with a combustion chamber (8), an evaporator, a superheater (9), an intermediate superheater (12), a condenset (14), a feed water preheater (16, 19, 19') regeneratively heated by steam, a steam turbine set (2) with a high-pressure section (4), a medium pressure section (5) and a low-pressure section (6), a flue gas line (22), connected to the combustion chamber (8), an air supply line (21), for the supply of combustion air to the burner in the combustion chamber (8) and an air preheater (3) with flue gas and combustion air passing therethrough. An air line (23) branches off from the air supply line (21) downstream of the air preheater (3) in said steam generation plant and supplies an air-fractionation unit (25). Air-coolers (34,35) are arranged in the air line (23) through which the condensate or feed water from the condensate/feed water circuit from the steam generator (1) flows. The oxygen output from the air fractionation unit (25) is connected to the burner of the combustion chamber (8) by means of an oxygen line (26).

Full Text	FORM 2 THE PATENT ACT 1970 (39 of 1970) The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10, and rule 13) 1. TITLE OF INVENTION STEAM GENERATION PLANT AND METHOD FOR OPERATION AND RETROFITTING OF A STEAM GENERATION PLANT 2. APPLICANT(S) a) Name b) Nationality c) Address MAN TURBO AG GERMAN Company STEINBRINKSTRASSE 1, 4 614 5 OBERHAUSEN, GERMANY 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed : - Description The invention relates to a steam generation plant with the features of the main term of the claim 1 and a procedure for operating or refurbishing a steam generation plant as per claim 17 or claim 23. This kind of steam generation plants requires the combustion of fossil fuel CO2, which is made responsible for the destruction of the ozone layer in the atmosphere. Therefore, by the industry and the universities joint developments in the energy sector are initiated for separation of CO2 from the exhaust gas. The joint developments include the conversion of CO with H2O to CO2 and H2 followed by separation of CO2 (IGCC process) and the combustion of fossil fuel with clean oxygen and subsequent CO2 separation (Oxy-Fuel procedure). The new construction of steam generation plants using Oxy-Fuel procedure will be implemented - based on present estimate - at a later date; i.e. some times in 10 to 20 years and that too with considerable investment costs. For refurbishing existing conventionally fired power plants the situation could be obviously more favorable, because much less investments would be necessary. Based on CO2 emissions, in conjunction with combustion with pure oxygen for an Oxy-Fuel refurbishing for cost reasons, and due to the size of compressor units being deployed, only power units in the size of 100 to 300 MW are considered. The invention is based on the task, to refurbish same type of steam generation plant with firing in such a way by using pure oxygen (oxy-Fuel procedure) that the steam generation plant can be run according to the Oxy-Fuel procedure as well as it can work in the conventional mode. The task pertaining to a type of steam generation plant and a procedure for operating or refurbishing such a plant according to the invention is resolved by the characteristic features of the claim 1 or claims 17 or 23. Advantageous designs of the invention are the subject matter of sub-claims. Through the invention based refurbishing on the Oxy-Fuel procedure, in the invention specific steam generation plant the existing regenerative feed water preheating and the existing air pre-heating on exhaust gas side of the steam generator are integrated and the intermediate overheating has been involved. The switching of steam generation plant is selected on the combustion air side in such a manner that an operation with air as lone oxygen carrier continues to be possible to unlimited extent. The refurbishing to an Oxy-Fuel plant thus follows without impairing the conventional steam generation plant in the possible fresh air mode. Scaling to larger units is possible. Several design examples of the invention are represented in the drawing and are explained in detail in the following along with advantages of the invention. It shows: Fig. 1 the sketch showing circuit of a steam generation plant with refurbishing on the operation with oxygen (Oxy-Fuel mode) and Fig. 2 to 4 other design forms of steam generator plant as per Fig. 1. The steam generation plant covers a steam generator 1 with a water-steam circulation, steam turbine set 2 and an air feed, an exhaust gas discharge and a regenerative air pre-heater (combustion air pre-heater) 3 heated with flue gas. To this extent the steam generation plant is of conventional design. It is explained below briefly to the extent necessary for understanding the invention. The steam turbine set 2 consists of one high pressure part 4, medium pressure part 5 and a low pressure part 6, which are arranged on a common shaft and drive a generator 7 for generating electrical energy. The represented steam generator 1 is developed as forced flow steam generator. The following description can also be used on a drum boiler. The steam generator 1 has a combustion chamber 8, which is provided with a firing driven by a gaseous fuel. Basically also the operation on coal basis is possible under consideration of a flue gas washing. In-line with evaporator heating areas of the combustion chamber 8 an over heater 9 is connected downstream. A high pressure steam pipe 10 connecting to the over heater 9 is carried to the high pressure part 4 of the steam turbine set 2. The exhaust steam outlet of high pressure part 4 is connected through connecting pipeline 11 with an intermediate over heater 12 of the steam generator 1. The intermediate overheater 12 is connected on the outlet side through an intermediate steam pipeline 13 with the medium pressure part 5 of the steam turbine set 2. The low pressure part 6 is connected downstream of the medium pressure part 5 on the steam side. The exhaust steam outlet of the low pressure part 6 is leads to a condenser 14. To the condenser 14 a condensate pipeline 15 is connected, in which there is a condensate pump 15'. In the condensate pipeline 15 behind each other several low pressure feed water preheaters 16, a thermal feed water degasser 17, a high pressure feed water pump 18 and several high pressure feed water preheaters 19, 19' have been arranged. The last high pressure feed water preheaterl9' is connected with an additional and flue gas heated feed water preheater or evaporator of the steam generator 1. The feed water preheaters 16, 19 are heated through bleeder steam of the high pressure part 4, medium pressure part 5 and low pressure part 6 of the steam turbine set 2. A blower 20 is arranged in an air supply pipeline 21, which is connected on the inlet side air part of the regenerative air preheater 3 and which is carried from the air preheater 3 to the firing of the combustion chamber 8, in order to feed this with combustion air. At the flue gas outlet of the steam generator 1 a flue gas pipeline 22 is connected, which is carried to the inlet side frame of the regenerative air preheater 3. Due to drawing reasons in the drawing the flue gas pipeline 22 is represented as broken line at points "b". Immediately after the air preheater 3 the flue gas pipeline 22 is carried to a chimney. The existing designs refer to a conventional steam generation plant. Now onwards the refurbishing of the steam generation plant is described as an Oxy-Fuel plant. This refurbishing can be subsequently undertaken on an existing or from the beginning in a new steam generation plant. From the air supply pipeline 21 downstream from the air preheater 3 an air pipeline 23 has been branched-off and is carried to an air compressor 24. The outlet of the air compressor 24 is carried to an air separation plant 25. The oxygen outlet of air separation plant 25 is connected through an oxygen pipeline 26 with a gas mixer 27, which is arranged in the air supply pipeline 21 between the air preheater 3 and the firing of the combustion chamber 8 of the steam generator 1. The air compressor 24 is driven by a drive steam turbine 28. The drive steam turbine 28 is impacted with steam as per Fig. 1, which is taken from the intermediate steam pipeline 13 between the intermediate overheater 12 of the steam generator 1 and the medium pressure part 5 of the steam turbine set 2 via a steam pipeline 29. For draftsmanship reasons the steam pipeline 29 in the drawing is represented with broken line at "a" places. Before the entry in the drive steam turbine 28 in the steam pipeline 29 a control valve 30 has been arranged. The exhaust steam outlet of the drive steam turbine 28 is carried to a condenser 31, which is connected via a condensate pipeline 32, in which a pump 33 is arranged, with the condensate pipeline 15 of the steam generator 1 upstream of the first low pressure feed water preheater of the low pressure feed water preheater group 16. In case the structural surroundings at the condenser 14 allow, the exhaust steam of the drive steam turbine 28 can be fed to the main condenser 14 of the steam generator 1. Thereby, the condenser 31 of the drive steam turbine 28 and the relevant condensate pump 33 can be done away with. In the Fig. 2 a drive steam turbine 28' has been shown, which is impacted not with intermediate steam but with bleeder steam. The bleeder steam is taken at a suitable bleeding stage 47 of the steam turbine set 2 and is fed via the steam pipeline 29' to the drive steam turbine 28'. According to Fig. 3 also a drive steam turbine 28" can be deployed, which is impacted via a steam pipeline 29" with steam from an external steam source 48. This external steam source can be a directly fired steam generator. In place of a drive steam turbine 28, 28', 28" also - as is shown in Fig. 4 - an electrical motor 49 can be deployed for driving the air compressor 24. In the air pipeline 23 between the air preheater 3 and the air compressor 24 two air coolers 34, 35 have been arranged. The air coolers 34, 35 like drive steam turbine 28 driving the air compressor 24 have been integrated in the water steam circulation of the steam generator 1. The air cooler 34 located upstream of air preheater 3 is flooded with high pressure feed water, which is taken from the condensate pipeline 15 downstream of high pressure feed water preheater 19 and is fed back upstream of this high pressure feed water preheater 19 in the condensate pipeline 15. If the control of the steam temperature in the intermediate overheater 12 of the steam generator 1 is done through an internal flue gas recirculation, then the last high pressure feed water preheater 19' can be integrated additionally in the air cooler 34. The air cooler 35 located downstream of the air preheater 3 is flooded by the low pressure feed water, which is taken from the condensate pipeline 15 downstream of low pressure feed water preheater group 16 and is fed back upstream of low pressure feed water preheater group 16 in the condensate pipeline 15. In the flue gas pipeline 22 downstream of the regenerative air preheater 3 and of branch towards a chimney 36 a recirculation blower 37 is arranged. Downstream of recirculation blower 37 the flue gas pipeline 22 branches into two flue gas sub-pipelines 38, 39. The first flue gas sub-pipeline 38 discharges in the gas mixer 27. The second flue gas sub-pipeline 39 is carried to a CO2 compressor 40. The CO2 compressor 40 is driven by an expander 42 and a motor/generator 41. The CO2 compressor 40 and the expander 42 are arranged together with the motor/generator 41 on a shaft. As shown with example in Fig. 3 and 4, the motor/generator 41 can also be done away with. Instead of this the air compressor 24, the expander 42 and the CO2 compressor 40 together with the drive steam turbine 28" or the electric motor 49 are arranged as driving device on a single shafting 50. It may be emphasized that the drive shafting shown in the Fig. 3 and 4 can also be deployed in a steam generator plant according to Fig. 1 and 2, similarly like the drive shafting as per Fig. 1 and 2 in a steam generator plant as per Fig. 3 and 4 is possible. In the second flue gas sub-pipeline 39 before its entry in the CO2 compressor 40 heat exchanger 43 is arranged for cooling the flue gas below the water condensation point, whereby follows the separation of water from the flue gas. The heat exchangers 43 are connected with the expander 42 via a connecting pipeline 44' through a Rankin cyclic process 44, in which as service medium a coolant with lower boiling temperature, e. g. NH3 is used. A pump 45 connected at the outlet of the expander 42 ensures for the circulation of the service medium through the heat exchangers 43 and the expander 42. As represented in the drawing and as has been described earlier, the air pipeline 23 leading via the air compressor 24 to the air separation plant 25 and containing air coolers 34, 35 and the oxygen pipeline 26 starting from the air separation plant 25 are switched parallel to the air feed pipeline 21 leading to the combustion chamber B. Check/ Control valves 46 in the air feed pipeline 21, air pipeline 23, oxygen pipeline 26, first flue gas sub-pipeline 38 and in the second flue gas sub-pipeline 39 ensure shutting-off the concerned pipeline or regulating medium flowing through the relevant pipeline. The previously described steam generation plant is driven as follows. The air necessary for the oxy-fuel-process, that means the air necessary for the operation with oxygen is cooled behind the regenerative air preheater 3 by means of steam turbine condensate to lowest possible temperatures and is compressed in the air compressor 24 to the pressure necessary for the air circulation plant 25. The drive of the air compressor 24 follows by means of drive steam turbine 28, 28', which is fed with the intermediate steam from the intermediate overheater 12 or with bleeding steam from the bleeder stage 47 of the medium pressure part 5 of the steam turbine 2. The lower output of the steam turbine set 2 is here low, because the extraction of the intermediate or bleeding steam is quantity-wise partially compensated by shifting of heat of combustion air in the condensate circulation of the steam generator 1 by closing or partially opening the bleeding points of the stem pipelines on the medium pressure and the low pressure side. The occurring condensate of the drive steam turbine 28,28' is integrated in the condensate circuit of the steam generator 1. Thereby, no additional de-gasser and no additional steam condensate system is necessary. Through the heat shifting of the heat of the combustion air from the air preheater 3 in the condensate-feed water circuit of the steam generator 1 follows a far reaching compensation of the lower output due to drawing intermediate steam or bleeding steam for driving the drive steam turbine 28, 28'. If the absorption property of the steam turbine set 2 is sufficient and if the generator 7 has still additional reserves, then one could decouple the drive of air compressor 24 from the intermediate steam track 24, consisting of intermediate steam pipeline 13 and bleeding stage 47, of medium pressure part 5 of the steam turbine set 2. Herein, for the drive an electrical motor as well as a pure steam turbine process with a direct fired steam generator are available. The advantage of such designs in case of latter lies in the free choice of steam parameters as well as in the improved dynamics of the changeover process of the steam generation plant on pure air operation, in case of trip of additional turbo machines for the Oxy-Fuel process. For improving efficiency of the drive process the intermediate cooler heat and post-cooler heat of air compressor 24 could be effectively integrated in the plant design of refurbishing. The air for the air circulation plant 25 is compressed by the air compressor 24 to the necessary pressure for the air circulation plant 25. In case of rising output of the steam generation plant the combination of axial and radial compressors with intermediate and post-coolers is available. Basically, also a purely motorized drive is possible. The start-up of the steam generation plant happens with 100% load of the blower 20, wherein approx. 60% of the air circulation plant 25, i. e. minimum load of the air circulation plant 25, and approx. 40 % of the air volume is fed to the steam generator I, i. e. minimum load of the forced flow through steam generator or a natural circulation boiler. The given values can vary depending on the process. The steam generator 1 runs in the partial load fresh air mode until the corresponding 02 quality is achieved in the air circulation plant 25. Then the switchover to Oxy-Fuel mode follows from partial load air mode on the respective partial load oxygen mode. Further load increases follow then under consideration of permissible values of air circulation plant 25. The starting from oxygen mode to air mode follows then in reverse direction. Through deletion of nitrogen in the oxygen combustion, in comparison with the fresh air mode, the flue gas mass flows reduce in the flue gas path of the steam generator 1 matching simultaneous rise of firing temperatures. The rise in the firing temperatures would lead to considerable thermal load in the pipes of combustion chamber 8 of the steam generator 1. Through dosing of predetermined high flue gas re-feed in the firing system of the steam generator 1 via the gas mixer 27, however, the mass flows as well as the combustion temperatures are regulated to similar values like in fresh air mode. Through carrying together oxygen and re-circulated flue gas in the gas mixer 27 similar 02 capacities like in the fresh air mode are achieved. For thermodynamic reasons the re-circulated flue gas is drawn after the air preheater 3. As already mentioned, all system parts belonging to the Oxy-Fuel-Process are switched parallel to the steam generation plant. Besides, in the air supply pipeline 21, air pipeline 23, oxygen pipeline 26, first flue gas sub-pipeline 38 and the second flue gas sub-pipeline 39 shut-off/control valves 46 are arranged. In this manner the Oxy-Fuel process is so integrated in the steam generation plant 1 that at anytime pure fresh air mode without oxygen feed is possible. For this purpose the respective shut-off / control valves 46 are to be closed. A pure fresh air mode of the steam generation plant 1 is possible even in case of a failure or shut down of turbo machines like air compressor 24, expander 42 and CO2 compressor 40. A A short circuit of parallel switched system parts belonging to oxy-fuel process after their completed erection follows during the audit of steam generator plant. The residual flue gases, mainly consisting of CO2 and H2O, are cooled for removing the water content via the Rankin circuit process 44 on NH3 base much below the water dew point of the flue gas. Through the escaping evaporation heat of the water vapor portion and the latent heat of the flue gases additional electrical energy can be recovered via the expander 42. The expander 42 drives via the motor/generator 41 the C02 compressor 40, which delivers depending on the purpose of usage the required pre-determined C02 final pressures. In this a compression at 200 bar for an EOR process (Enhanced Oil-Recovering process) can be achieved. Depending on the required drive output of the compressor 40 either motor or generator mode is available. WE CLAIM: 1. Steam generation plant covering - Steam generator (1) with a combustion chamber (8), evaporator, overheater (9), intermediate overheater (12), condenser (14), feed water preheaters heated regenerative through steam (16,19,19'), - Steam turbine set (2) with high pressure part (4), medium pressure part (5) and low pressure part (6), - Flue gas pipeline (22) immediately after the combustion chamber (8). - Air supply pipeline (21) for the supply of Combustion air in the firing of combustion chamber (8). - Air preheater (3) flooded by flue gas and combustion air Is characterized by the fact, - that from the air supply pipeline (21) downstream air pipeline (23), which can be shut, branched out from the air preheater (3) and is carried to an air circulation plant (25), that in the air pipeline (23) air coolers (34, 35) have been arranged, which are flooded by condensate or feed water from the condensate/feed water circuit of the steam generator (1) and - that the oxygen outlet of the air circulation plant (25) is connected through an oxygen pipeline (26) with the firing of combustion chamber (8). 2. Steam generation plant as per claim 1, is characterized by the fact that in the air pipeline (23) between the air coolers (34, 35) and the air circulation plant (25) an air compressor (24) has been arranged. 3. Steam generation plant as per claim 1 or 2, is characterized by the fact that the air pipeline (23) leading via air compressor (24) to the air circulation plant (25) and which accommodates air coolers (34, 35) and oxygen pipeline (26) originating from the air circulation plant (25) are switched in parallel to the air supply pipeline leading to the combustion chamber (8). 4. Steam generation plant as per one of the claims 1 to 3, is characterized by the fact that in the air supply pipeline (21), air pipeline (23) and oxygen pipeline (26) one each of shut-off/control valve (46) has been arranged. 5. Steam generation plant as per claim 2, is characterized by the fact that the air compressor (24) is driven by a drive steam turbine (28), which is impacted with steam from the intermediate overheater (12) of the steam generator (1). 6. Steam generation plant as per claim 2, is characterized by the fact that the air compressor (24) is driven by a drive steam turbine (281), which is impacted with steam from a bleeding stage (a1) of the steam turbine set (2). 7. Steam generation plant as per claim 2, is characterized by the fact that the air compressor (24) is driven by a drive steam turbine (2B"), which is impacted with steam from an external steam source (48). 8. Steam generation plant as per claim 2, is characterized by the fact that the air compressor (24) is driven by an electrical motor (49). 9. Steam generation plant as per claim 5 or 6, is characterized by the fact that the drive steam turbine (28,.28') is connected with a condenser (31), whose condensate outlet is connected with the condensate circuit of the steam generator (1). 10. Steam generation plant as per one of the claims 1 to 9, is characterized by the fact that downstream from the flue gas pipeline (22) a first flue gas sub-pipeline (38) has been branched from the air preheater (3), that the first flue gas sub-pipeline (38) is carried to a gas mixer (27), that in the gas mixer (27) discharge oxygen pipeline (26) coming from the air circulation plant (25) and the air supply pipeline (21) and that the gas mixer (27) is connected with the firing of the combustion chamber (8). 11. Steam generation plant as per one of the claims 1 to 10, is characterized by the fact that downstream from the flue gas pipeline (22) a second flue gas sub-pipeline (39) has been branched from the air preheater (3) and that the second flue gas sub-pipeline (39) is carried to a CO2 compressor (40). 12. Steam generation plant as per claim 11, is characterized by the fact that in the second flue gas sub-pipeline (39) heat exchangers (43) are arranged for the cooling of flue gas occurring during operation of combustion chamber (8) with oxygen from the air circulation plant (25} below their water due point and that the heat exchangers (43) are connected with an expander (42) through a connecting pipeline (441) through Rankin circuit process (44) by using coolant with lower boiling point. 13. Steam generation plant as per claim 11 or 12, is characterized by the fact that the CO2 compressor (40) is driven by the expander (42). 14. Steam generation plant as per claim 13 is characterized by the fact that between the CO2 compressor (40) and the expander (42) a motor/Generator (41) is arranged. 15. Steam generation plant as per one of the claims 11 to 13, is characterized by the fact that the air compressor (24), expander (42), CO2 compressor (40) and the drive medium from the drive steam turbine (28, 28', 28") or electrical motor (49) are arranged on a common single shafting (50). 16. Steam generation plant as per one of the claims 1 to 13, is characterized by the fact that the steam generator (1) of an existing or newly installed steam generation plant is designed for being suitable to refurbish through the air cooler (34, 35), air compressor (24), air circulation plant (25), Rankin circuit (44) and the CO2 compressor (40). 17. Process for operating a steam generation plant covering - Steam generator (1) with combustion chamber (8), evaporator, overheater (9), intermediate overheater (12), condenser (14), feed water preheaters (16,19, 19'), which are regenerative heated by steam, - Steam turbine set (2) with high pressure part (4), medium pressure part (5) and low pressure part (6), - Flue gas pipeline (22), which is connected to the combustion chamber (8), - Air supply pipeline (21), through which the combustion air is fed in the firing of combustion chamber (8), - Air preheater (3), which is flooded by flue gas and combustion air, Is characterized by the fact, - that downstream from the air preheater (3) an air flow is branched through an air pipeline (23) and carried to an air circulation plant (25), - that the air flow in the air pipeline (23) is cooled by condensate or feed water from the condensate / feed water circuit of the steam generator (I), - that the cooled air flow in an air circulation plant (25) is separated in an 02 portion and an N2 portion - and that the 02 portion is fed through oxygen pipeline (26) to the firing of combustion chamber (8). 18. Process as per claim 17, is characterized by the fact that the flue gases occurring during the operation of combustion chamber (8) with oxygen from the air circulation plant (25) are separated downstream from the air preheater (3) via a second flue gas sub-pipeline (39), that the flue gases are cooled below their water dew point in heat exchangers (43) through Rankin circuit process (44) covering these heat exchangers (43) and an expander (42) by means of a coolant with low boiling point and are, thereafter, compressed in a CO2 compressor (40). 19. Process as per claim 17 or 18, is characterized by the fact that after shutdown or failure of turbo machines, consisting of air compressor (24), expander (42), C02 compressor (40), and after closing of shut-off / control valves (46) the steam generator (1) is run with fresh air via the air supply pipeline (21). 20. Process as per one of the claims 17 to 19, is characterized by the fact that during the inspection of steam generator plant the equipment switched parallel to the steam generator (1) are closed for a short while after end of mounting. 21. Process as per claim 18, is characterized by the fact that in the C02 compressor (40) the flue gas consisting mainly of C02 and to a lesser extent of H20 is compressed to an outlet pressure required for further usage. 22. Process as per one of the claims 18 to 21, is characterized by the fact that the integration of intermediate and post cooling heats of the air compressor (24) via the Rankin circuit process (44) with the connecting pipeline (44') heat exchangers (43) and the expander (42) additional drive energy is generated for the CO2 compressor (40). 23. Process for refurbishing a steam generation plant covering - Steam generator (1) with combustion chamber (8), compressor, overheater (9), intermediate overheater (12), condenser (14), feed water preheaters (16,19, 19'), which are heated regenerative through steam, - Steam turbine set (2) with high pressure part (4), medium pressure part (5) and low pressure part (6), - Flue gas pipeline (22), which is connected to the combustion chamber (8), - Air supply pipeline (21), through which the combustion air is supplied in the firing of the combustion chamber (8), - Air preheater (3), which is flooded by flue gas and combustion air, Is characterized by the fact, - that downstream of air preheater (3) an air flow is separated via an air pipeline (23) and is carried to an air circulation plant (25), - that the air flow in the air pipeline (23) is cooled through condensate or feed water from the condensate/feed water circuit of the steam generator (1), - that the cooler air flow in an air circulation plant (25) is separated in a 02 portion and an N2 portion - and that the 02 portion is fed via oxygen pipeline (26) to the firing of the combustion chamber (8). 24. Process as per claim 23, is characterized by the fact that the flue gases occurring during the operation of the combustion chamber (8) with oxygen from the air circulation plant (25) are separated downstream from the air preheater (3) via a second flue gas sub-pipeline (39), that the flue gases are cooled below their water dew point in heat exchangers (43) through Rankin circuit process (44) covering these heat exchangers (43) and an expander (42) by using a coolant with low boiling point and are compressed thereafter in a C02 compressor (40). 25. Process as per claim 23 or 24 is characterized by the fact that after shutdown or failure of turbo machines, consisting of air compressor (24), expander (42), CO2 compressor (40), and closure of shut-off / control valves (46) the steam generator (1) is run with fresh air via the air supply pipeline (21). 26. Process as per one of the claims 23 to 25, is characterized by the fact that during the inspection of steam generator plant the equipment switched parallel to the steam generator (1) are closed for a short while after end of mounting. 27. Process as per claim 24, is characterized by the fact that in the C02 compressor (40) the flue gas consisting mainly of CO2 and to a lesser extent H20 is compressed to a outlet pressure necessary for further usage. 28. Process as per one of the claims 24 to 27, is characterized by the fact that the integration of intermediate and post cooling heats of the air compressor (24) through the Rankin circuit process (44) with the connection pipeline (44') Heat exchangers (43) and the expander (42) additional drive energy is generated for the C02 compressor (40). Dated this 6th day of December, 2007 ABSTRACT The invention relates to a steam generation plant, comprising a steam generator (1) with a combustion chamber (8), an evaporator, a superheater (9), an intermediate superheater (12), a condenset (14), a feed water preheater (16, 19, 19') regeneratively heated by steam, a steam turbine set (2) with a high-pressure section (4), a medium pressure section (5) and a low-pressure section (6), a flue gas line (22), connected to the combustion chamber (8), an air supply line (21), for the supply of combustion air to the burner in the combustion chamber (8) and an air preheater (3) with flue gas and combustion air passing therethrough. An air line (23) branches off from the air supply line (21) downstream of the air preheater (3) in said steam generation plant and supplies an air-fractionation unit (25). Air-coolers (34,35) are arranged in the air line (23) through which the condensate or feed water from the condensate/feed water circuit from the steam generator (1) flows. The oxygen output from the air fractionation unit (25) is connected to the burner of the combustion chamber (8) by means of an oxygen line (26). To, The Controller of Patents, The Patent Office, Mumbai

Full Text

FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION
(See Section 10, and rule 13)
1. TITLE OF INVENTION
STEAM GENERATION PLANT AND METHOD FOR OPERATION AND RETROFITTING
OF A STEAM GENERATION PLANT

2. APPLICANT(S)
a) Name
b) Nationality
c) Address

MAN TURBO AG GERMAN Company STEINBRINKSTRASSE 1, 4 614 5 OBERHAUSEN, GERMANY

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

Description
The invention relates to a steam generation plant with the features of the main term of the claim 1 and a procedure for operating or refurbishing a steam generation plant as per claim 17 or claim 23.
This kind of steam generation plants requires the combustion of fossil fuel CO2, which is made responsible for the destruction of the ozone layer in the atmosphere. Therefore, by the industry and the universities joint developments in the energy sector are initiated for separation of CO2 from the exhaust gas.
The joint developments include the conversion of CO with H2O to CO2 and H2 followed by separation of CO2 (IGCC process) and the combustion of fossil fuel with clean oxygen and subsequent CO2 separation (Oxy-Fuel procedure). The new construction of steam generation plants using Oxy-Fuel procedure will be implemented - based on present estimate - at a later date; i.e. some times in 10 to 20 years and that too with considerable investment costs.
For refurbishing existing conventionally fired power plants the situation could be obviously more favorable, because much less investments would be necessary. Based on CO2 emissions, in conjunction with combustion with pure oxygen for an Oxy-Fuel refurbishing for cost reasons, and due to the size of compressor units being deployed, only power units in the size of 100 to 300 MW are considered.
The invention is based on the task, to refurbish same type of steam generation plant with firing in such a way by using pure oxygen (oxy-Fuel procedure) that the steam generation plant can be run according to the Oxy-Fuel procedure as well as it can work in the conventional mode.
The task pertaining to a type of steam generation plant and a procedure for operating or refurbishing such a plant according to the invention is resolved by the

characteristic features of the claim 1 or claims 17 or 23. Advantageous designs of the invention are the subject matter of sub-claims.
Through the invention based refurbishing on the Oxy-Fuel procedure, in the invention specific steam generation plant the existing regenerative feed water preheating and the existing air pre-heating on exhaust gas side of the steam generator are integrated and the intermediate overheating has been involved. The switching of steam generation plant is selected on the combustion air side in such a manner that an operation with air as lone oxygen carrier continues to be possible to unlimited extent. The refurbishing to an Oxy-Fuel plant thus follows without impairing the conventional steam generation plant in the possible fresh air mode. Scaling to larger units is possible.
Several design examples of the invention are represented in the drawing and are explained in detail in the following along with advantages of the invention. It shows:
Fig. 1 the sketch showing circuit of a steam generation plant with refurbishing on the operation with oxygen (Oxy-Fuel mode) and
Fig. 2 to 4 other design forms of steam generator plant as per Fig. 1.
The steam generation plant covers a steam generator 1 with a water-steam circulation, steam turbine set 2 and an air feed, an exhaust gas discharge and a regenerative air pre-heater (combustion air pre-heater) 3 heated with flue gas. To this extent the steam generation plant is of conventional design. It is explained below briefly to the extent necessary for understanding the invention.
The steam turbine set 2 consists of one high pressure part 4, medium pressure part 5 and a low pressure part 6, which are arranged on a common shaft and drive a generator 7 for generating electrical energy.

The represented steam generator 1 is developed as forced flow steam generator. The following description can also be used on a drum boiler. The steam generator 1 has a combustion chamber 8, which is provided with a firing driven by a gaseous fuel. Basically also the operation on coal basis is possible under consideration of a flue gas washing. In-line with evaporator heating areas of the combustion chamber 8 an over heater 9 is connected downstream. A high pressure steam pipe 10 connecting to the over heater 9 is carried to the high pressure part 4 of the steam turbine set 2.
The exhaust steam outlet of high pressure part 4 is connected through connecting pipeline 11 with an intermediate over heater 12 of the steam generator 1. The intermediate overheater 12 is connected on the outlet side through an intermediate steam pipeline 13 with the medium pressure part 5 of the steam turbine set 2. The low pressure part 6 is connected downstream of the medium pressure part 5 on the steam side.
The exhaust steam outlet of the low pressure part 6 is leads to a condenser 14. To the condenser 14 a condensate pipeline 15 is connected, in which there is a condensate pump 15'. In the condensate pipeline 15 behind each other several low pressure feed water preheaters 16, a thermal feed water degasser 17, a high pressure feed water pump 18 and several high pressure feed water preheaters 19, 19' have been arranged. The last high pressure feed water preheaterl9' is connected with an additional and flue gas heated feed water preheater or evaporator of the steam generator 1. The feed water preheaters 16, 19 are heated through bleeder steam of the high pressure part 4, medium pressure part 5 and low pressure part 6 of the steam turbine set 2.
A blower 20 is arranged in an air supply pipeline 21, which is connected on the inlet side air part of the regenerative air preheater 3 and which is carried from the air preheater 3 to the firing of the combustion chamber 8, in order to feed this with combustion air. At the flue gas outlet of the steam generator 1 a flue gas pipeline 22 is connected, which is carried to the inlet side frame of the regenerative air preheater

3. Due to drawing reasons in the drawing the flue gas pipeline 22 is represented as broken line at points "b". Immediately after the air preheater 3 the flue gas pipeline
22 is carried to a chimney.
The existing designs refer to a conventional steam generation plant. Now onwards the refurbishing of the steam generation plant is described as an Oxy-Fuel plant. This refurbishing can be subsequently undertaken on an existing or from the beginning in a new steam generation plant.
From the air supply pipeline 21 downstream from the air preheater 3 an air pipeline
23 has been branched-off and is carried to an air compressor 24. The outlet of the air
compressor 24 is carried to an air separation plant 25. The oxygen outlet of air
separation plant 25 is connected through an oxygen pipeline 26 with a gas mixer 27,
which is arranged in the air supply pipeline 21 between the air preheater 3 and the
firing of the combustion chamber 8 of the steam generator 1.
The air compressor 24 is driven by a drive steam turbine 28. The drive steam turbine 28 is impacted with steam as per Fig. 1, which is taken from the intermediate steam pipeline 13 between the intermediate overheater 12 of the steam generator 1 and the medium pressure part 5 of the steam turbine set 2 via a steam pipeline 29. For draftsmanship reasons the steam pipeline 29 in the drawing is represented with broken line at "a" places. Before the entry in the drive steam turbine 28 in the steam pipeline 29 a control valve 30 has been arranged. The exhaust steam outlet of the drive steam turbine 28 is carried to a condenser 31, which is connected via a condensate pipeline 32, in which a pump 33 is arranged, with the condensate pipeline 15 of the steam generator 1 upstream of the first low pressure feed water preheater of the low pressure feed water preheater group 16.
In case the structural surroundings at the condenser 14 allow, the exhaust steam of the drive steam turbine 28 can be fed to the main condenser 14 of the steam

generator 1. Thereby, the condenser 31 of the drive steam turbine 28 and the relevant condensate pump 33 can be done away with.
In the Fig. 2 a drive steam turbine 28' has been shown, which is impacted not with intermediate steam but with bleeder steam. The bleeder steam is taken at a suitable bleeding stage 47 of the steam turbine set 2 and is fed via the steam pipeline 29' to the drive steam turbine 28'.
According to Fig. 3 also a drive steam turbine 28" can be deployed, which is impacted via a steam pipeline 29" with steam from an external steam source 48. This external steam source can be a directly fired steam generator.
In place of a drive steam turbine 28, 28', 28" also - as is shown in Fig. 4 - an electrical motor 49 can be deployed for driving the air compressor 24.
In the air pipeline 23 between the air preheater 3 and the air compressor 24 two air coolers 34, 35 have been arranged. The air coolers 34, 35 like drive steam turbine 28 driving the air compressor 24 have been integrated in the water steam circulation of the steam generator 1. The air cooler 34 located upstream of air preheater 3 is flooded with high pressure feed water, which is taken from the condensate pipeline 15 downstream of high pressure feed water preheater 19 and is fed back upstream of this high pressure feed water preheater 19 in the condensate pipeline 15. If the control of the steam temperature in the intermediate overheater 12 of the steam generator 1 is done through an internal flue gas recirculation, then the last high pressure feed water preheater 19' can be integrated additionally in the air cooler 34. The air cooler 35 located downstream of the air preheater 3 is flooded by the low pressure feed water, which is taken from the condensate pipeline 15 downstream of low pressure feed water preheater group 16 and is fed back upstream of low pressure feed water preheater group 16 in the condensate pipeline 15.

In the flue gas pipeline 22 downstream of the regenerative air preheater 3 and of branch towards a chimney 36 a recirculation blower 37 is arranged. Downstream of recirculation blower 37 the flue gas pipeline 22 branches into two flue gas sub-pipelines 38, 39. The first flue gas sub-pipeline 38 discharges in the gas mixer 27.
The second flue gas sub-pipeline 39 is carried to a CO2 compressor 40. The CO2 compressor 40 is driven by an expander 42 and a motor/generator 41. The CO2 compressor 40 and the expander 42 are arranged together with the motor/generator 41 on a shaft.
As shown with example in Fig. 3 and 4, the motor/generator 41 can also be done away with. Instead of this the air compressor 24, the expander 42 and the CO2 compressor 40 together with the drive steam turbine 28" or the electric motor 49 are arranged as driving device on a single shafting 50. It may be emphasized that the drive shafting shown in the Fig. 3 and 4 can also be deployed in a steam generator plant according to Fig. 1 and 2, similarly like the drive shafting as per Fig. 1 and 2 in a steam generator plant as per Fig. 3 and 4 is possible.
In the second flue gas sub-pipeline 39 before its entry in the CO2 compressor 40 heat exchanger 43 is arranged for cooling the flue gas below the water condensation point, whereby follows the separation of water from the flue gas. The heat exchangers 43 are connected with the expander 42 via a connecting pipeline 44' through a Rankin cyclic process 44, in which as service medium a coolant with lower boiling temperature, e. g. NH3 is used. A pump 45 connected at the outlet of the expander 42 ensures for the circulation of the service medium through the heat exchangers 43 and the expander 42.
As represented in the drawing and as has been described earlier, the air pipeline 23 leading via the air compressor 24 to the air separation plant 25 and containing air coolers 34, 35 and the oxygen pipeline 26 starting from the air separation plant 25 are switched parallel to the air feed pipeline 21 leading to the combustion chamber B.

Check/ Control valves 46 in the air feed pipeline 21, air pipeline 23, oxygen pipeline 26, first flue gas sub-pipeline 38 and in the second flue gas sub-pipeline 39 ensure shutting-off the concerned pipeline or regulating medium flowing through the relevant pipeline.
The previously described steam generation plant is driven as follows. The air necessary for the oxy-fuel-process, that means the air necessary for the operation with oxygen is cooled behind the regenerative air preheater 3 by means of steam turbine condensate to lowest possible temperatures and is compressed in the air compressor 24 to the pressure necessary for the air circulation plant 25.
The drive of the air compressor 24 follows by means of drive steam turbine 28, 28', which is fed with the intermediate steam from the intermediate overheater 12 or with bleeding steam from the bleeder stage 47 of the medium pressure part 5 of the steam turbine 2. The lower output of the steam turbine set 2 is here low, because the extraction of the intermediate or bleeding steam is quantity-wise partially compensated by shifting of heat of combustion air in the condensate circulation of the steam generator 1 by closing or partially opening the bleeding points of the stem pipelines on the medium pressure and the low pressure side. The occurring condensate of the drive steam turbine 28,28' is integrated in the condensate circuit of the steam generator 1. Thereby, no additional de-gasser and no additional steam condensate system is necessary. Through the heat shifting of the heat of the combustion air from the air preheater 3 in the condensate-feed water circuit of the steam generator 1 follows a far reaching compensation of the lower output due to drawing intermediate steam or bleeding steam for driving the drive steam turbine 28, 28'.
If the absorption property of the steam turbine set 2 is sufficient and if the generator 7 has still additional reserves, then one could decouple the drive of air compressor 24 from the intermediate steam track 24, consisting of intermediate steam pipeline 13 and bleeding stage 47, of medium pressure part 5 of the steam turbine set 2. Herein,

for the drive an electrical motor as well as a pure steam turbine process with a direct fired steam generator are available. The advantage of such designs in case of latter lies in the free choice of steam parameters as well as in the improved dynamics of the changeover process of the steam generation plant on pure air operation, in case of trip of additional turbo machines for the Oxy-Fuel process. For improving efficiency of the drive process the intermediate cooler heat and post-cooler heat of air compressor 24 could be effectively integrated in the plant design of refurbishing.
The air for the air circulation plant 25 is compressed by the air compressor 24 to the necessary pressure for the air circulation plant 25. In case of rising output of the steam generation plant the combination of axial and radial compressors with intermediate and post-coolers is available. Basically, also a purely motorized drive is possible.
The start-up of the steam generation plant happens with 100% load of the blower 20, wherein approx. 60% of the air circulation plant 25, i. e. minimum load of the air circulation plant 25, and approx. 40 % of the air volume is fed to the steam generator I, i. e. minimum load of the forced flow through steam generator or a natural circulation boiler. The given values can vary depending on the process. The steam generator 1 runs in the partial load fresh air mode until the corresponding 02 quality is achieved in the air circulation plant 25. Then the switchover to Oxy-Fuel mode follows from partial load air mode on the respective partial load oxygen mode. Further load increases follow then under consideration of permissible values of air circulation plant 25. The starting from oxygen mode to air mode follows then in reverse direction.
Through deletion of nitrogen in the oxygen combustion, in comparison with the fresh air mode, the flue gas mass flows reduce in the flue gas path of the steam generator 1 matching simultaneous rise of firing temperatures. The rise in the firing temperatures would lead to considerable thermal load in the pipes of combustion chamber 8 of the steam generator 1. Through dosing of predetermined high flue gas

re-feed in the firing system of the steam generator 1 via the gas mixer 27, however, the mass flows as well as the combustion temperatures are regulated to similar values like in fresh air mode. Through carrying together oxygen and re-circulated flue gas in the gas mixer 27 similar 02 capacities like in the fresh air mode are achieved. For thermodynamic reasons the re-circulated flue gas is drawn after the air preheater 3.
As already mentioned, all system parts belonging to the Oxy-Fuel-Process are switched parallel to the steam generation plant. Besides, in the air supply pipeline 21, air pipeline 23, oxygen pipeline 26, first flue gas sub-pipeline 38 and the second flue gas sub-pipeline 39 shut-off/control valves 46 are arranged. In this manner the Oxy-Fuel process is so integrated in the steam generation plant 1 that at anytime pure fresh air mode without oxygen feed is possible. For this purpose the respective shut-off / control valves 46 are to be closed. A pure fresh air mode of the steam generation plant 1 is possible even in case of a failure or shut down of turbo machines like air compressor 24, expander 42 and CO2 compressor 40. A A short circuit of parallel switched system parts belonging to oxy-fuel process after their completed erection follows during the audit of steam generator plant.
The residual flue gases, mainly consisting of CO2 and H2O, are cooled for removing the water content via the Rankin circuit process 44 on NH3 base much below the water dew point of the flue gas. Through the escaping evaporation heat of the water vapor portion and the latent heat of the flue gases additional electrical energy can be recovered via the expander 42.
The expander 42 drives via the motor/generator 41 the C02 compressor 40, which delivers depending on the purpose of usage the required pre-determined C02 final pressures. In this a compression at 200 bar for an EOR process (Enhanced Oil-Recovering process) can be achieved. Depending on the required drive output of the compressor 40 either motor or generator mode is available.

WE CLAIM:
1. Steam generation plant covering
- Steam generator (1) with a combustion chamber (8), evaporator, overheater (9), intermediate overheater (12), condenser (14), feed water preheaters heated regenerative through steam (16,19,19'),
- Steam turbine set (2) with high pressure part (4), medium pressure part (5) and low pressure part (6),
- Flue gas pipeline (22) immediately after the combustion chamber (8).
- Air supply pipeline (21) for the supply of Combustion air in the firing of combustion chamber (8).
- Air preheater (3) flooded by flue gas and combustion air Is characterized by the fact,
- that from the air supply pipeline (21) downstream air pipeline (23), which can be shut, branched out from the air preheater (3) and is carried to an air circulation plant (25),
that in the air pipeline (23) air coolers (34, 35) have been arranged, which are flooded by condensate or feed water from the condensate/feed water circuit of the steam generator (1) and
- that the oxygen outlet of the air circulation plant (25) is connected through
an oxygen pipeline (26) with the firing of combustion chamber (8).
2. Steam generation plant as per claim 1, is characterized by the fact that in the air pipeline (23) between the air coolers (34, 35) and the air circulation plant (25) an air compressor (24) has been arranged.
3. Steam generation plant as per claim 1 or 2, is characterized by the fact that the air pipeline (23) leading via air compressor (24) to the air circulation plant (25) and which accommodates air coolers (34, 35) and oxygen pipeline (26) originating from the air circulation plant (25) are switched in parallel to the air supply pipeline leading to the combustion chamber (8).

4. Steam generation plant as per one of the claims 1 to 3, is characterized by the fact that in the air supply pipeline (21), air pipeline (23) and oxygen pipeline (26) one each of shut-off/control valve (46) has been arranged.
5. Steam generation plant as per claim 2, is characterized by the fact that the air compressor (24) is driven by a drive steam turbine (28), which is impacted with steam from the intermediate overheater (12) of the steam generator (1).
6. Steam generation plant as per claim 2, is characterized by the fact that the air compressor (24) is driven by a drive steam turbine (281), which is impacted with steam from a bleeding stage (a1) of the steam turbine set (2).
7. Steam generation plant as per claim 2, is characterized by the fact that the air compressor (24) is driven by a drive steam turbine (2B"), which is impacted with steam from an external steam source (48).
8. Steam generation plant as per claim 2, is characterized by the fact that the air compressor (24) is driven by an electrical motor (49).
9. Steam generation plant as per claim 5 or 6, is characterized by the fact that the drive steam turbine (28,.28') is connected with a condenser (31), whose condensate outlet is connected with the condensate circuit of the steam generator (1).
10. Steam generation plant as per one of the claims 1 to 9, is characterized by the fact that downstream from the flue gas pipeline (22) a first flue gas sub-pipeline (38) has been branched from the air preheater (3), that the first flue gas sub-pipeline (38) is carried to a gas mixer (27), that in the gas mixer (27) discharge oxygen pipeline (26) coming from the air circulation plant (25) and the air supply pipeline (21) and that the gas mixer (27) is connected with the firing of the combustion chamber (8).

11. Steam generation plant as per one of the claims 1 to 10, is characterized by the fact that downstream from the flue gas pipeline (22) a second flue gas sub-pipeline (39) has been branched from the air preheater (3) and that the second flue gas sub-pipeline (39) is carried to a CO2 compressor (40).
12. Steam generation plant as per claim 11, is characterized by the fact that in the second flue gas sub-pipeline (39) heat exchangers (43) are arranged for the cooling of flue gas occurring during operation of combustion chamber (8) with oxygen from the air circulation plant (25} below their water due point and that the heat exchangers (43) are connected with an expander (42) through a connecting pipeline (441) through Rankin circuit process (44) by using coolant with lower boiling point.
13. Steam generation plant as per claim 11 or 12, is characterized by the fact that the CO2 compressor (40) is driven by the expander (42).
14. Steam generation plant as per claim 13 is characterized by the fact that between the CO2 compressor (40) and the expander (42) a motor/Generator (41) is arranged.
15. Steam generation plant as per one of the claims 11 to 13, is characterized by the fact that the air compressor (24), expander (42), CO2 compressor (40) and the drive medium from the drive steam turbine (28, 28', 28") or electrical motor (49) are arranged on a common single shafting (50).
16. Steam generation plant as per one of the claims 1 to 13, is characterized by the fact that the steam generator (1) of an existing or newly installed steam generation plant is designed for being suitable to refurbish through the air cooler (34, 35), air compressor (24), air circulation plant (25), Rankin circuit (44) and the CO2 compressor (40).

17. Process for operating a steam generation plant covering
- Steam generator (1) with combustion chamber (8), evaporator, overheater (9), intermediate overheater (12), condenser (14), feed water preheaters (16,19, 19'), which are regenerative heated by steam,
- Steam turbine set (2) with high pressure part (4), medium pressure part (5) and low pressure part (6),
- Flue gas pipeline (22), which is connected to the combustion chamber (8),
- Air supply pipeline (21), through which the combustion air is fed in the firing of combustion chamber (8),
- Air preheater (3), which is flooded by flue gas and combustion air, Is characterized by the fact,
- that downstream from the air preheater (3) an air flow is branched through an air pipeline (23) and carried to an air circulation plant (25),
- that the air flow in the air pipeline (23) is cooled by condensate or feed water from the condensate / feed water circuit of the steam generator (I),
- that the cooled air flow in an air circulation plant (25) is separated in an 02 portion and an N2 portion
- and that the 02 portion is fed through oxygen pipeline (26) to the firing of combustion chamber (8).
18. Process as per claim 17, is characterized by the fact that the flue gases occurring during the operation of combustion chamber (8) with oxygen from the air circulation plant (25) are separated downstream from the air preheater (3) via a second flue gas sub-pipeline (39), that the flue gases are cooled below their water dew point in heat exchangers (43) through Rankin circuit process (44) covering these heat exchangers (43) and an expander (42) by means of a coolant with low boiling point and are, thereafter, compressed in a CO2 compressor (40).
19. Process as per claim 17 or 18, is characterized by the fact that after shutdown or failure of turbo machines, consisting of air compressor (24), expander (42),

C02 compressor (40), and after closing of shut-off / control valves (46) the steam generator (1) is run with fresh air via the air supply pipeline (21).
20. Process as per one of the claims 17 to 19, is characterized by the fact that during the inspection of steam generator plant the equipment switched parallel to the steam generator (1) are closed for a short while after end of mounting.
21. Process as per claim 18, is characterized by the fact that in the C02 compressor (40) the flue gas consisting mainly of C02 and to a lesser extent of H20 is compressed to an outlet pressure required for further usage.
22. Process as per one of the claims 18 to 21, is characterized by the fact that the integration of intermediate and post cooling heats of the air compressor (24) via the Rankin circuit process (44) with the connecting pipeline (44') heat exchangers (43) and the expander (42) additional drive energy is generated for the CO2 compressor (40).
23. Process for refurbishing a steam generation plant covering

- Steam generator (1) with combustion chamber (8), compressor, overheater (9), intermediate overheater (12), condenser (14), feed water preheaters (16,19, 19'), which are heated regenerative through steam,
- Steam turbine set (2) with high pressure part (4), medium pressure part (5) and low pressure part (6),
- Flue gas pipeline (22), which is connected to the combustion chamber (8),
- Air supply pipeline (21), through which the combustion air is supplied in the firing of the combustion chamber (8),
- Air preheater (3), which is flooded by flue gas and combustion air, Is characterized by the fact,
- that downstream of air preheater (3) an air flow is separated via an air pipeline (23) and is carried to an air circulation plant (25),

- that the air flow in the air pipeline (23) is cooled through condensate or feed water from the condensate/feed water circuit of the steam generator (1),
- that the cooler air flow in an air circulation plant (25) is separated in a 02 portion and an N2 portion
- and that the 02 portion is fed via oxygen pipeline (26) to the firing of the combustion chamber (8).

24. Process as per claim 23, is characterized by the fact that the flue gases occurring during the operation of the combustion chamber (8) with oxygen from the air circulation plant (25) are separated downstream from the air preheater (3) via a second flue gas sub-pipeline (39), that the flue gases are cooled below their water dew point in heat exchangers (43) through Rankin circuit process (44) covering these heat exchangers (43) and an expander (42) by using a coolant with low boiling point and are compressed thereafter in a C02 compressor (40).
25. Process as per claim 23 or 24 is characterized by the fact that after shutdown or failure of turbo machines, consisting of air compressor (24), expander (42), CO2 compressor (40), and closure of shut-off / control valves (46) the steam generator (1) is run with fresh air via the air supply pipeline (21).
26. Process as per one of the claims 23 to 25, is characterized by the fact that during the inspection of steam generator plant the equipment switched parallel to the steam generator (1) are closed for a short while after end of mounting.
27. Process as per claim 24, is characterized by the fact that in the C02 compressor (40) the flue gas consisting mainly of CO2 and to a lesser extent H20 is compressed to a outlet pressure necessary for further usage.

28. Process as per one of the claims 24 to 27, is characterized by the fact that the integration of intermediate and post cooling heats of the air compressor (24) through the Rankin circuit process (44) with the connection pipeline (44') Heat exchangers (43) and the expander (42) additional drive energy is generated for the C02 compressor (40).
Dated this 6th day of December, 2007

ABSTRACT
The invention relates to a steam generation plant, comprising a steam generator (1) with a combustion chamber (8), an evaporator, a superheater (9), an intermediate superheater (12), a condenset (14), a feed water preheater (16, 19, 19') regeneratively heated by steam, a steam turbine set (2) with a high-pressure section (4), a medium pressure section (5) and a low-pressure section (6), a flue gas line (22), connected to the combustion chamber (8), an air supply line (21), for the supply of combustion air to the burner in the combustion chamber (8) and an air preheater (3) with flue gas and combustion air passing therethrough. An air line (23) branches off from the air supply line (21) downstream of the air preheater (3) in said steam generation plant and supplies an air-fractionation unit (25). Air-coolers (34,35) are arranged in the air line (23) through which the condensate or feed water from the condensate/feed water circuit from the steam generator (1) flows. The oxygen output from the air fractionation unit (25) is connected to the burner of the combustion chamber (8) by means of an oxygen line (26).
To,
The Controller of Patents,
The Patent Office,
Mumbai

STEAM GENERATION PLANT

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