FI80761C - FOERFARANDE FOER TORKNING AV VATTEN INNEHAOLLANDE AEMNE I EN KRAFTVERKSPROCESS OCH TORKANORDNING FOER ANVAENDNING VID FOERFARANDET. - Google Patents

Description

80761 1 Method for drying an aqueous substance Dryer used in a power plant process and method Förfarande för torkning av vatten innehallande ämne 1 en kraft-verksprocess och torkanordnlng för användnlng vld förfarandet 5

The invention relates to a drying method for a dryer used in a power plant process and method.

10

Today, the aqueous material is generally dried without pressure. Likewise, fuel containing water is burned without pressure, e.g. with a grate boiler for dust combustion or fluidized bed combustion. In known equipment solutions, the dryer and power plant process [15 are not connected in the best possible way in terms of the overall efficiency of the process. The process connections between the dryers and the incinerators have not been implemented in the best possible way. The current sowing methods and the dryers used in them are not at all suitable for pressurized combustion or gasification methods.

20

It is an object of the invention to find an improvement in the drying of an aqueous substance. In the invention, it has been realized to form a dryer into a pressurized dryer, in which the steam generated in the drying is passed as injection steam to a gas turbine.

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The steam generated in the pressurized dryer is led to the combustion chamber of the gas turbine, where it replaces part of the air coming through the compressor. At the same time, the power requirement of the compressor is reduced and an even larger part of the turbine power is converted to generator power. The net power from the gas turbine ... 30 increases by up to about 40 X. The efficiency of the gas turbine then increases by about 25 X as the final temperature of the flue gases decreases.

Plenty of air is needed because it keeps the combustion chamber temperature at the desired level, i.e. at a level that the materials allow. When air is replaced by steam in the sense of cooling, the power required to compress the air is reduced and more power is left for the generator. Steam generation requires thermal power and little energy is required to use pump 2 80761 1 to pump the water entering the evaporator. However, the energy required by the pump is only a fraction of what compression would require.

According to the invention, injection steam is generated in a pressurized dryer from water obtained from the material to be dried, and the thermal energy required for such drying is preferably brought from waste heat obtained elsewhere in the process, e.g. from waste gas from gas turbine combustion gases.

10

The method according to the invention for drying an aqueous substance is mainly characterized in that the steam generated during the drying is directed at least in part along a separate unit into injection steam in a gas turbine combustor 15

The dryer according to the invention is mainly characterized in that one of the internal space of the dryer into which the water-containing drying agent is introduced for drying is used to conduct the steam generated in the drying to the gas turbine as injection steam.

20

The invention will now be described with reference to some preferred embodiments of the invention shown in the figures of the accompanying drawings, to which, however, the invention is not intended to be exclusively limited.

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Figure 1 schematically shows an industrial process comprising a pressurized dryer and an electricity generating gas turbine.

Figure 2 shows schematically a pressurized dryer-gas turbine-30 combination in which the waste heat of the gas turbine combustion gases is utilized in the drying of the water-containing material of an industrial process.

Figure 3 shows the connection between the dryer and the heat recovery device connected to the flue gas duct, which is applicable e.g. to the embodiment of Fig. 35 2.

li 3 80761 1 As indicated in Figure 1, the water-containing drying agent A shown by the arrow L is introduced into a pressurized dryer 10. By pressurization in this application it is understood that an excess pressure relative to atmospheric pressure has been produced in the dryer 10 by steam generation. The overpressure is typically in the range of 5 to 50 bar. The heat energy is introduced into the heat exchanger 12 and the heat energy is transferred to the material to be dried. In general, any water-containing drying material can be used. Drying takes place in a dryer 10 at the pressure of the combustion chamber of the gas turbine. The moisture contained in the substance to be dried is obtained as a process medium by directing it along the compound 11 to the combustion chamber 13a of the combustion or gasification device 13. In a pressurized dryer 10, the moist substance is dried to e.g. 20% humidity. The combustion device 12 can be implemented with clean fuel or ash-containing fuel, either by direct combustion, or a solution is also possible in which direct combustion is replaced by fuel gasification 15 or by partial gasification and combustion of the generated gas.

The steam introduced from the dryer 10 along the connection 11 is thus led to the combustion chamber 13a of the combustion unit 13 of the gas turbine blower 14. In the combustion chamber 13a, this steam replaces part of the air coming through the compressor 14.

At the same time, the power requirement of the compressor 15 is reduced and an even larger part of the power of the gas turbine is transferred to the power of the generator 16.

A large amount of air is needed because it keeps the temperature of the combustion chamber 13a at the desired level, i.e. at the level allowed by the materials. 25 When air is replaced by steam for cooling purposes, the power required to compress the air is reduced and more power is left for the generator. Steam generation requires thermal power.

The dried material A 1 from the dryer 10 is transferred to other uses of the industrial process 30, e.g. as a raw material for particle board or directly to one of the industrial process boilers and / or to the combustion device 13 for the gas turbine 14 shown in Fig. A, where the material is A 1. The dryer 10 can also act as a dryer for an intermediate or final product of an industrial process.

35 4 80761 1 The combustion device 13 comprises a combustion chamber 13a pressurized by a compressor 15. The compressor 15 produces the necessary combustion air, which is led to the combustion device 13 via the compressed air piping 11. The compressor 15 raises the pressure to e.g. about 12 bar, the amount of which is also produced by means of steam-5 formation in the dryer 10 in its internal drying space 10a. At this pressure, the air is then led to the combustor 13 in its combustion chamber 13a. Due to the combustion of fuel A £, the mixture of air and flue gases produced by the combustion of the fuel heats up to approx. 850 ... 1200 ° C. At least part of the steam separated from the wet material introduced into the dryer 10 is introduced into the combustion device 13 through its combustion chamber 13a via a steam pipe 11 10. The purpose of the steam supply is to control the final temperature of the combustion chamber, in which case it replaces the excess air normally required. Thanks to the feed, the compressor power is reduced and the net power of the process is increased.

15 The flue gases are further led along the flue gas pipeline 17 to a gas turbine 14 where the gases expand and generate kinetic energy. The kinetic energy drives a compressor 15 on the same shaft and a generator 16, which generates electricity. The power from the gas turbine 14 is greater than the power required by the compressor 15, whereby more than 20 power is recovered from the generator 16 of the gas turbine 14. After the gas turbine 14, the flue gases are led via a duct 18 to a separate waste heat recovery device 19, e.g.

The invention can also be applied to a combined heat and power plant in which, in addition to the gas turbine 25, there is a steam turbine generating electricity. In this case, all or part of the thermal energy required for drying can be taken from the tap steam of the steam turbine.

Figure 2 shows an embodiment of the invention in which the flue gas heat recovery device 19 after the gas turbine 14 30 is used as a source of energy supplied to the pressurized dryer 10. There is a heat transfer circuit 20 between the pressurized dryer 10 and the heat recovery device 19. In the heat transfer tank 20, e.g. water can be circulated. In the waste heat boiler in the waste heat boiler 21, the heat from the flue gases is transferred to the water of the circuit 20 and the water is circulated in the dryer 10, its heat exchanger 22, whereby the heat energy from the flue gases is transferred to the material to be dried in the heat exchanger 22. The steam generated in the dryer 10 is further passed along the connection 11 to the gas turbine 14, its pressurized part to the combustion or gasification device 12 by injection steam.

Figure 3 shows a third preferred embodiment of the invention. A water-containing material is introduced into the Pai-5 quadruple dryer 10 and fluidized by recirculating steam in a steam atmosphere. The steam generated during drying is circulated in the circuit 23 by means of a steam blower 24. The steam is circulated through a heat exchanger 25, which heat exchanger 25 is arranged in a heat recovery source 19, e.g. a flue gas waste heat boiler 10. The dried material is removed from the top of the dryer 10.

From the recirculation circuit 23 of the heat transfer basin, a part of the steam is taken through the distribution point 26 to the duct 11 and further to other uses, e.g. just by injecting steam from the gas turbine 14. In the dryer 10 itself, separate heat exchanger piping is required in its wear 10a.

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Claims (8)

A method for drying an aqueous material in a power plant process, comprising introducing an aqueous material (A 1) to be dried into a pressurized dryer (10) and introducing thermal energy to dry the aqueous material (A 2), characterized in that the steam generated during drying is directed at least in part by a separate unit for injection steam into the combustion device (13) of the gas turbine (14). 1 Claims Method according to Claim 1, characterized in that an overpressure of approx. 5 to 50 bar is produced in the dryer (10). Method according to the preceding claim, characterized in that the overpressure is produced by means of the steam generation 15 of the dryer (10). Method according to one of the preceding claims, characterized in that the thermal energy required for drying the substance is taken from the waste heat of the flue gases of the gas turbine (14) or from the intake vapors of the steam turbine 20. Method according to one of the preceding claims, characterized in that the steam generated in the dryer is recycled through a waste heat boiler, where it is superheated and the steam is returned to the dryer to be dried to a dryer where it transfers thermal energy to the fuel drying. A dryer (10) for drying an aqueous material, the dryer (10) comprising an internal space (10a) of the pressurized dryer (10) into which the aqueous material to be dried (Aβ) is introduced and which dryer (10) comprises means (19). , 20,20a) to transfer the thermal energy required for drying to the material to be dried, characterized in that "" from the internal space of the dryer (10) to which the water-containing material to be dried (A 2) is introduced for drying there is one (11) for conducting drying steam to the gas turbine (14). ) for injection steam.7 80761 6 80761 Dryer according to the preceding claim, characterized in that the dryer comprises a heat transfer circuit (20) for transferring heat from the gas turbine exhaust gases or the steam turbine intake steam to the drying of the water-containing substance. 5 Dryer according to Claim 6 or 7, characterized in that the dryer (10) comprises a circuit between the heat recovery bed (19) and the pressurized drying space (10a) and a steam blower (24), the steam generated during drying of the aqueous medium being led to the heat recovery device (19). ), preferably to a flue gas waste heat boiler and from there on to a dryer (10) to a substance drying space (10a), the apparatus further comprising one steam recirculation circuit (11) through which at least a portion of the steam can be transferred to injection gas to the gas turbine (14). 15 20 25: 30 35 δ 80761 ^ Patentkrav