FI66483B - KOMBINERAD VAERMEKRAFTANLAEGGNING - Google Patents

Description

Ί r - ANNOUNCEMENT,, Λ „M (11) utlAggnincsskrift 66483 ^ T ^ (51) K» .lk ^ / taco.3 F 22 B 1/18 FINLAND — FINLAND pi) 800584 '(7Ί) HilflMMy »—A« wB> mlii «d— 27.02.80 (23) AHmpIMI — Glklfh« t * 4af 27.02.80 (41) TmNm | hMmIi * I - BMvttoffantNf 13.10.80 rrjiÄÄ «bsstasäse-» · “« (32) (33) ( 31) Requested Muoikwt — B ^ Srtl prior ** 12.04.79

Switzerland-Switzerland (CH) 3495 / 79-2 (70 Gebruder Sulzer Aktiengesel1schaft, CH-8401 Winterthur, Switzerland)

Schweiz (CH) (72) Emile Aguet, Winterthur, Switzerland-Schweiz (CH) (74) Oy Kolster Ab (54) Combined heat and power plant - Kombinerad värmekraftanläggning

The invention relates to a thermal power plant according to the preamble of claim 1. Combining gas turbines with steam power plants gives a better overall efficiency than with a steam power plant alone. However, one of the preconditions for the operation of such combined heat and power plants is that clean, ash-free gases are fed to the easily polluted and consumable gas turbine. The starting point of the invention is therefore a combined thermal power plant in which the gas turbine fuel is not heated directly by the combustion of impure fuel, but mainly by heat transfer, so that practically clean air flows through the gas turbine. The advantage of such a power plant is that it can use different fuels. Its disadvantages are again the higher acquisition costs and the slightly lower efficiency of the gas turbine group due to the pressure drop in the air heater.

The present invention seeks to improve po. the efficiency of the combined heat and power plant and at the same time eliminate the above disadvantages.

66483 This is achieved by the structural features of the invention set out in claim 1. By distributing the expanded air in the gas turbine, only a part of the total air is then used to burn the impure fuel, and the remaining air, which may burn a relatively small amount of clean fuel, e.g. in the start-up phase, can be cooled to a low dew point, possibly even below. The exhaust gas loss is then very small, which significantly improves the overall efficiency of the equipment. Another advantage of the connection according to the invention is that the flue gas filter at the outlet of the steam generator can be constructed for a considerably smaller amount of exhaust gas. In addition, the flue for the flue gases of the steam generator can be dimensioned smaller; the exhaust gases from the exhaust heat exchanger can be blown out through the low exhaust manifold as they are ecologically safe.

By appropriately dividing the feed water into a part of the steam generator and the exhaust heat exchanger, the exhaust gases of the exhaust heat exchanger can be cooled to a temperature below 100 ° C, e.g. to 50 ° C. The exhaust gases from the exhaust heat exchanger can be cooled to a very low temperature precisely when it utilizes only the exhaust heat of the gas turbine, which also uses coal dust, so that the dew-point-increasing hydrocarbons are not burned in the branch line air stream.

Additional advantages are also obtained by constructing the steam generator furnace as a vortex bed furnace, which makes the SC4 and SO2 content of the exhaust gases significantly lower by adding sulfur-binding substances. Another advantageous feature of the vortex bed furnace is that, due to the low combustion temperature, the NO content of the exhaust gases is low.

Thus, when the first part of the closed heat transfer system of the gas turbine is arranged at least in the lower part of the vortex bed, the inlet temperature of the gas turbine remains sufficiently high even when the plant is operating at part load.

The final heating of the compressed air in the compressor of the gas turbine group is preferably carried out in the second part of the heat transfer system arranged above the vortex bed, because the material of this heating surface is thus subjected to less thermal stress.

3 66483

The vortex bed is preferably provided above the first part of the heat transfer system with a steam generator evaporative fire surface, which, due to the water-half-high heat transfer number, ensures that the temperatures of the material remain suitable on this heating surface.

If a heat transfer is provided in the gas line of the steam generator below the second part of the system, yet another evaporating fire surface connected to the evaporating fire surface in the vortex bed, this preferably affects the load on the steam generator.

When a superheating surface is provided between the second evaporating fire surface and the second part of the heat transfer system for the steam generated in the evaporating fire surfaces, it is not necessary to make major corrections to the fresh steam temperatures, e.g. by spraying water on the steam.

By using devices which can move the interface of the finished combustion in the vortex bed at the evaporating fire surface arranged in the vortex bed vertically, the steam production of the steam generator can be adjusted depending on the load so that the superheated steam only has to be sprayed to remove dynamic disturbances.

When a suction gas fan is arranged at the outlet of the flue gas duct of the steam generator, the total pressure drop on the gas side is minimal. In addition, it is easier to feed carbon and additives to the vortex bed.

Some structural examples related to the invention will now be described in more detail with reference to the accompanying drawing, in which Figure 1 is a diagram of a thermal power plant according to the invention in which the exhaust heat exchanger is formed solely as a steam generator. heating, and Figure 3 shows a detail of Figure 2.

The compressor 1 shown in Fig. 1, which is on the same shaft as the gas turbine 2 and the generator 3, supplies compressed air via a pipe 4 to the first part 6 of the closed heat transfer system 6 arranged in the steam generator 7. The outlet of the first part is connected to the second part 11 of the heat transfer system. From the 11 outlets, a hot air line 12 is arranged to the inlet of the gas turbine 2. The outlet of the gas turbine 2 is divided into an inlet pipe 15 leading to the furnace 16 of the steam generator 7 and a branch pipe 18 communicating with the exhaust heat exchanger 20. The fire housing 16 of the steam generator 7 is a vortex bed; 4 66483 Figure 1 shows the fuel particles burning in a vortex motion with slashes. The first part 6 is located in the lower part of the vortex bed 16 and the second part 11 above the bed in the flue gas duct of the steam generator 7. The steam generator 7 further has heating surfaces 40, 44, 46 and 47 associated with the steam circulation; the water is supplied from the supply water tank 30 by a supply line 31. The supply line 31 has a supply pump 32, a supply valve 33 and a high-pressure pre-heater 34, and is connected to a preheater (Economiser) 40 in the steam generator 40. Its outlet is connected 44, the outlet of which is connected by a line 45 to a second evaporator 46. This in turn is connected to a superheater 47. The outlet of the superheater 47 is connected to a steam turbine 50 by a fresh steam line 48 with a fresh steam valve 49. The outlet of the turbine 50 is connected to a condenser 51. transferred to the supply water tank 30. The branch line 18 to the discharge heat exchanger 20 has a choke 19. A pre-heater (Economiser) 60 is arranged in the discharge heat exchanger 20, to which water is supplied from the supply line 31 via a supply pump 56 and a valve 57. A preheater 62 and a superheater 64 are connected to the preheater 60, also located in the exhaust heat exchanger 20. From the outlet of the superheater 64, a fresh steam line 65 with a valve 66 is connected to the supply point of the steam turbine 50. In the lower pressure range of the turbine 50 there is an outlet pipe 68 of the high-pressure preheater 34. A bypass line with a bypass valve 69 is arranged in the first part 6 of the closed heat transfer system.

The air drawn in by the compressor 1 is fed at a pressure of 8 bar to the first part 6 and heated there to about 700 ° C. The additional heating of the air takes place in the second part 11, after which it is expanded in a gas turbine 2 to about 1.03 bar n, at 413 ° C. The hot air flowing out of the turbine 2 is led along a pipe 15 to a vortex bed 16 and along a branch line 18 to an exhaust heat exchanger 20. Coal and lime powder are fed to the vortex bed 16. The coal burns, and the sulfur released is then formed into gypsum by means of lime. The gypsum and slag are then removed from the side of the equipment (not shown). The exhaust gases from the vortex bed are cooled in a second section 11, a superheater 47, a second evaporator 46 and a further 66483 preheater 40 to a temperature of about 150 ° C and possibly cleaned in a dust separator (not shown) before being introduced into the flue. The hot air supplied to the exhaust heat exchanger 20 cools to about 50 ° C. The evaporator 62 is arranged so that the steam bubbles generated therein rise with the flow of the water-steam mixture.

The branch line 18 conducts at full load at least 30% of the air leaving the gas turbine 2 at full load. When the air flowing through the exhaust heat exchanger 20 can be cooled to a relatively low temperature because it has no combustion water and the total exhaust gases of the equipment are very small. The heat efficiency thus becomes exceptionally high. Po. Another advantage of the system is that the amount of air fed to the vortex bed can be changed very quickly by means of a choke 19 as required. As a result, the desired combustion temperature can easily be adjusted according to the load, i.e. according to the amount of fuel fed and the amount of heat delivered by the vortex bed. The combustion temperature can also be influenced by the bypass valve 69.

In the structure according to Fig. 2, compressed air flows through a preheater 5 arranged in the exhaust heat exchanger 20 to a first part 6 of a closed heat transfer system arranged in a vortex bed 16. In addition, a combustion chamber 13 is provided in the gas hot turbine 2. that the steam circuit passing through the steam generator 7 now has a steam-water drum 42 to which the evaporators 44 and 46 are connected as a connection related to natural recycling. In addition, the superheater 47, which in this structure is in the gas stream below the second evaporator 46, is divided into two parts 47a and 47b, between which a water spray device 43 is connected to change the temperature of the steam.

The condensate pipe 53 leading from the condensate pump 52 to the feed water tank 30 has three condensate preheaters 54 to which a condensate low temperature preheater 58 (in parallel) is connected via a line 55 to the end of the exhaust heat exchanger 20. At the branch point of the line 55 there is a distribution valve 80, the control of which takes place by means of the temperature of the air at the outlet of the exhaust heat exchanger 20 (not shown in more detail in the figure). In addition, the exhaust heat exchanger 20 is provided with a preheater (Economiser) 40 arranged between the preheater 5 and the low temperature preheater 58, which is connected in parallel with the preheater 40 in the steam generator 7. As shown by way of example in Figure 3, 71. It operates by means of a controller 72 which receives a control signal along line 73 from a differential element 74. The two inputs of this (74) are connected to a temperature sensor 75 and 78, respectively, which takes into account the output temperature of the preheater 40 and the steam temperature 42. Thanks to this connection, the flow through the preheater 40 is always measured in such a way that no evaporation is certain to occur. Due to the relatively high water pressure and low air temperature, evaporation does not occur in the preheater 40 '.

In the apparatus according to Figure 2, a suction traction fan 85 is arranged at the gas outlet of the steam generator 7, the displacement amount (power) of which can be adjusted depending on the load. Thus, the fan 85 performs the distribution function of the choke 19 in the apparatus shown in Fig. 1. In order to provide a function depending on the load of the transfer rate, a measuring element 86, e.g. a differential pressure receiver, is arranged on the basis of the vortex bed surface, which acts on the fan 85 via the regulator 87 (adjustable setpoint) and thus also the combustion air supply so that the air supply increases . In addition to or instead of this function, the controller 87 may provide a corresponding signal to the coal and lime supply point 88 of the vortex bed 16; as the surface rises, the fuel supply decreases. By means of the suction blower 85, all pressure losses are reduced, whereby the efficiency of the equipment increases.

A bypass line 89 comprising a bypass valve 90 branches between the preheater 5 and the first part 6 and connects to the hot air line 12, i.e. it bypasses the first part 6 and the second part 11 of the closed heat transfer system. The line 89 replaces the bypass line 69 of Fig. 1, and enables faster thermal corrections of the hot air before the air enters the gas turbine 2. A mixing section must be provided in the mouthpiece of the line 89 if sufficient mixture is not otherwise obtained in the combustion chamber 13.

The apparatus according to Figures 2 and 3 operates in principle according to the apparatus of Figure 1. However, the difference is that no steam is generated or superheated in the exhaust heat exchanger 20. Thus, all the steam is generated at a high pressure, which in turn means that relative to the amount of steam produced, this apparatus dissipates less heat of condensation than the apparatus of Figure 1, so that the efficiency of the apparatus of Figure 2 is higher.

In principle, the air - if the combustion chamber 13 is not heated - can be cooled, in the exhaust heat exchanger 20, even to the air intake temperature without the formation of mist or condensation. However, the condensate temperature and the cost associated with the size of the low temperature preheater 58 generally eliminate the use of such a low degree of cooling.

As is generally the case in steam generators, the walls of the steam generator 7 and the exhaust heat exchanger 20 are preferably sealed welded pipe walls and connected as preheaters or evaporators (not shown in more detail in the figures) to the steam generator circulation system.

Claims (11)

A combined heat and power plant with a steam generator (7) comprising a furnace (16) and a gas turbine group (1,2), the output of the gas turbine group compressor (1) being connected to a closed heat transfer system (5,6) arranged in a steam generator (7), 11) to the inlet of the gas turbine (2) and the outlet of the gas turbine to the furnace (16) of the steam generator (7), characterized in that an outlet heat exchanger (20) is further connected to the outlet of the gas turbine (2) by means of a branch line (18). , 62,64; 5,40 ', 58) is dimensioned so that the exhaust gases leaving it are cooled to a lower temperature than the flue gases leaving the steam generator (7). Thermal power plant according to Claim 1, characterized in that the exhaust heat exchanger (20) is connected to the supply water system (60; 40 ', 58) so that its exhaust gases are cooled to below 100 ° C in normal operation. Thermal power plant according to Claim 1 or 2, characterized in that the exhaust heat exchanger (20) utilizes only the exhaust heat of the gas turbine (2). Thermal power plant according to one of Claims 1 to 3, characterized in that the furnace (16) of the steam generator (7) is formed as a vortex bed furnace. Thermal power plant according to Claim 4, characterized in that at least part (6) of the closed heat transfer system (5, 6, 11) of the gas turbine group (1, 2) is arranged in a vortex bed (16). Thermal power plant according to Claim 5, characterized in that the first part (6) of the closed heat transfer system (5, 6, 11) is arranged in the lower region of the vortex bed (16) and the second part (11) of the closed heat transfer system is arranged in the steam generator (7). ) to the flue gas duct and that in addition to the vortex bed (16) is provided an evaporator fire surface (44) of the steam generator (7) located above the first part (6) of the closed heat transfer system (5,6,11). Thermal power plant according to Claim 6, characterized in that in addition to the evaporator burner surface (44) arranged in the vortex bed (16), there is a second evaporator burner surface (46) in the flue gas duct of the steam generator (7). , 11) on the downstream side of the second part (11). Thermal power plant according to Claim 7, characterized in that the flue gas duct of the steam generator (7) has a superheater heating surface (47) between the second evaporator fire surface (46) and the second part (11) of the closed heat transfer system (5, 6, 11). , 46) for the generated steam. 8 66483 Thermal power plant according to one of Claims 6 to 8, characterized in that a measuring element (86) operating according to the height of the vortex bed (16) is provided, which acts on the coal and lime supply (88) via a controller (87) with adjustable nominal value. . Thermal power plant according to one of Claims 4 to 9, characterized in that a suction fan (85) is arranged at the flue gas outlet of the steam generator (7). Thermal power plant according to one of Claims 1 to 10, characterized in that the distribution of the gas stream leaving the gas turbine (2) in the furnace (16) of the steam generator (7) and in the exhaust heat exchanger (20) is adjustable. 1 o 66483