JP2554060B2 - Combined generation system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a combined power generation system of a gas turbine power generation system and a steam turbine power generation system, and more particularly to a combined power generation system with an improved fuel processing system.

[Conventional technology]

Recently, a combined power generation system that combines a gas turbine power generation system and a steam turbine power generation system driven by its exhaust heat energy has been drawing attention as a new technology that can effectively utilize clean fuel such as LNG vaporized gas. There is. FIG. 7 is a diagram showing a schematic structure of a conventional device of this type (Japanese Patent Application No. 57-215914). The fuel a is supplied to the fuel unit 1 through the fuel preheater 7a and the fuel vaporizer (fuel evaporator) 7b with a built-in reaction catalyst in sequence, and the fuel a is burned together with the combustion air b compressed by the compressor 2c. The gas turbine power generation system 2 is driven by the combustion energy. The gas turbine power generation system 2 includes a gas turbine 2a, a generator 2b driven by the turbine output, and an air compressor 2c for the combustion air b to obtain a power generation output. Then, the high-temperature exhaust gas of the gas turbine power generation system 2 is discharged through the exhaust main 3a of the exhaust heat boiler system 3 .

An exhaust branch pipe 8a is provided by connecting the upstream end and the downstream end in the exhaust main 3a, and in the exhaust main 3a, the steam generator 3c from the upstream side toward the downstream side, the feed water preheating A device 3b and a fuel preheater 7a are provided, and a fuel vaporizer 7b is provided in the exhaust branch pipe 8a.

A branch duct inlet damper 8b and a branch duct outlet damper 8c are provided at the inlet and outlet of the exhaust branch pipe 8a, respectively, so that the flow rate of exhaust gas branched in the exhaust branch pipe 8a can be controlled. Also, the steam generator 3c and the water supply preheater
The 3b is disposed in the exhaust main pipe 3a at a position between the inlet damper 8b and the outlet damper 8c.

Therefore, the fuel a supplied to the gas turbine 2a is
In advance, it is heated by the fuel preheater 7a in the exhaust main pipe 3a, and further, by the fuel vaporizer 7b in the exhaust branch pipe 8a, the heat energy of the high-temperature exhaust gas c from the gas turbine 2a is given to chemically react, It will be converted into secondary fuel with high combustion energy.

On the other hand, the steam generated in the exhaust heat boiler system 3 is supplied to the steam turbine 4a of the steam turbine power generation system 4 , and the power generator 4b
Is driven to obtain turbine output. Then, the steam after driving the steam turbine 4a is supplied to the condenser 5, liquefied by the cooling water d and then supplied to the feed water preheater 3b via the cooling water pump 6, and further the steam generator. It is heated by 3c and becomes high-pressure steam.

[Problems to be solved by the invention]

In the above combined power generation system, a gas turbine power generation system
The fuel a supplied to No. 2 can absorb heat from the exhaust gas in the fuel preheater 7a and the fuel vaporizer 7b to increase the amount of heat possessed. There is an economic problem because it requires a lot. A large amount of catalyst is required for the fuel vaporizer 7b,
This is because the catalyst is provided up to the functional part that includes various functional parts and does not actually require the catalyst.

Therefore, an object of the present invention is to provide a combined power generation system in which the amount of expensive catalyst is small and the equipment cost is low.

[Means for solving problems]

In order to achieve the above object, the present invention connects a gas turbine power generation system, an exhaust main for circulating high temperature exhaust gas from this gas turbine power generation system, and an upstream end and a downstream end of the exhaust main. An exhaust branch pipe provided with a damper for adjusting the flow rate of the exhaust gas, which is provided at each of an inlet side and an outlet side of the exhaust branch pipe, and an inlet and an outlet of the exhaust branch pipe in the exhaust main pipe. Thermal energy of the exhaust gas which is disposed between the steam turbine power generation system driven by high pressure steam and the fuel which is disposed in the exhaust branch pipe and is supplied to the gas turbine power generation system through the exhaust branch pipe. A fuel preheater that preheats the fuel vapor, an evaporator that vaporizes the fuel that has been preheated by the fuel preheater, and a fuel vapor that is vaporized by the evaporator that is disposed between the inlet and the outlet of the exhaust branch pipe. Against A combined power generation system including a reactor having a catalyst for converting the secondary fuel having high fuel energy into a secondary fuel, and a superheater which superheats the secondary fuel from the reactor and supplies it to the gas turbine power generation system. is there.

[Action]

As described above, the conventional fuel vaporizer is divided into a plurality of functional parts, and the catalyst is contained only in the reactor that chemically absorbs heat.Therefore, the amount of the catalyst is smaller than that of the conventional one. This reduces equipment costs.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. Here, the points different from the conventional example shown in FIG. 7 will be mainly described.

FIG. 1 shows a basic structure and a plant structure of a fuel processing system for explaining the embodiment.

The fuel a is heat-exchanged with the gas turbine exhaust (reactor exhaust) e in the fuel processing system to increase the retained heat amount, and then supplied to the gas turbine power generation system 2 from the main fuel line 12a. The gas turbine exhaust e is provided with a branch duct inlet damper 8b and a branch duct outlet damper 8c so as to be commensurate with the consumption amount of the fuel a.
The remaining gas turbine exhaust f is generated by the exhaust boiler system 3 and supplied to the steam turbine power generation system 4 . Thus, the combined power generation system is composed of the gas turbine power generation system 2 and the steam turbine power generation system 4 .

On the other hand, in the fuel processing system, a superheater 12, a reactor 11, a heater 10, an evaporator 9 and a fuel preheater 7a are sequentially arranged from the inflow side of the gas turbine exhaust e toward the outflow side of the exhaust e, and an endothermic chemical reaction is performed. The catalyst used for is contained only in the reactor 11. The superheater 12 and the reactor 11 are the superheater 12 and the gas turbine power generation system, respectively.
2 between the combustor 1 and the superheater bypass line 12b, and between the reactor 11 and the superheater 12 the reactor bypass line 13
Which is used for driving adjustment. The reaction catalyst contained in the reactor 11 may be deteriorated in performance during long-term use, and in this case, the reaction temperature is raised by using the main fuel line 12a.

The reactor 11 may be a methanol decomposition reactor, a methanol steam reforming reactor, or both. The methanol decomposition reaction in this case is as follows (1),
It becomes like the formula (2).

_{CH 3 OH → CO + 2H 2} ΔH25 ℃ = 21.7k cal / mol ... (1) CH 3 OH + nH 2 O → (2 + n) H 2 + (1-n) CO + nCO 2 ...
(2) 0 <n <1 Here, the methanol steam reforming reaction is expressed by the following equation (3).

CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ ΔH 25 ° C. = 11.8 kcal / mol (3) The following catalyst is used as the catalyst built in the reactor 11.

That is, when the reactor 11 is a methanol decomposition reactor, a platinum catalyst (for example, 18 m ³ ) and a nickel-copper catalyst (for example, 36 m ³ ) are used. Is placed on the low temperature side downstream, that is, the exhaust gas temperature
Save catalyst cost by using heat-resistant platinum catalyst only in the reactor section higher than 500 ~ 400 ℃.

When the reactor 11 is a methanol steam reforming reactor, a reactor filled with a copper-zinc catalyst (for example, 100 m ³ ) is used, and exhaust heat at 505 ° C. (decomposition) and 509 ° C. (steam reforming) is used. tests were conducted using computer simulation by the combined power generation system shown in Figure 1 to be introduced into the boiler 3.

Methanol is Chemical Grade [MeOH 99.7 (wt%), H ₂
O 0.1 (wt%)]. In the decomposition reaction, an extremely small amount of water vapor (Stcam / MeOH = 0.1 mol) is used to prolong the life of the catalyst.
e ratis) so that a mixture of methanol and water is mixed, or steam is supplied from a boiler 3 to methanol vapor. A mixture of methanol (56265kg / h) and steam (3105kg / h) was supplied at 265 ° C to cause decomposition reaction in the reactor 11 ,
9370kg / h of a gas _{(H 2: 64.6vol%, co} : 27.1vol%, co 2: 3.6v
ol%, CH ₃ OH: 3.5vol%, H ₂ O: 0.6vol%, Others: 0.6vol%)
I got The conversion of methanol was 90%.

In addition, the gas turbine is burned by burning this gas in the combustor 1.
2a is rotated, a part of the exhaust heat is recovered by the exhaust heat boiler 3 , and the steam turbine is rotated by the steam generated by the steam generator (not shown), the output of the gas turbine 2a is 127.670KW and the output of the steam turbine system 4 is 31400KW, the total plant was 159.070KW, and the power generation efficiency was 51.2% (lower heating value standard).

On the other hand, in the steam reforming reaction, methanol (61504 kg /
Supply a mixture of h) and steam (63506 kg / h) at 250 ° C,
The reactor 11 to perform the steam reforming reaction, 125,010kg / h) of gas _{(H 2: 58.3vol%, co} : 0.5vol%, co 2: 17.1vol%, CH 2 O
H: 1.8vol%, H ₂ O: 20.3vol%) was obtained. Steam is boiler 3
Alternatively, it is supplied from the steam extracted from the steam turbine 4 . The conversion of methanol was 91.6%.

If you turn the gas turbine and steam turbine in the same way as above,
Output of gas turbine system 2 is 149.660 KW, steam turbine system 4
Output was 22.400KW, total plant was 172.060KW, and power generation efficiency was 50.7% (lower heating value standard).

This is because the extracted steam of the steam turbine 4 is used as reaction steam, and a high steam turbine output is obtained.

The gas turbine exhaust amount e varies depending on the model of the gas turbine, but it is because (exhaust flow rate, exhaust temperature, fuel consumption rate) varies depending on the manufacturer model.

As an example of the case of the gas turbine adopted in the examination of the system of the present invention described above, Therefore, the amount of heat necessary for the reaction of methanol was secured.

Table 1 below shows the results of comparison with combined power generation in the case where methanol was used as a liquid in order to explain the utilization state of heat in an easy-to-understand manner.

Methanol decomposition can recover about 7% more heat of reaction than methanol steam reforming, and as a result, methanol consumption (per KW) in the gas turbine can be saved. Methanol decomposition corresponds to a fuel saving of about 6% compared to liquid methanol.

FIGS. 2 and 3 are views for explaining the heat absorption state from the gas turbine exhaust e of the fuel processing system, in which the preheater 7a, the evaporator 9, the heater 10, the reactor 11, and the superheater 12 are replaced. The heat quantity is indicated by the Q suffix. After the reaction, the superheater 12 is fuel a
Which enhance the sensible heat, but absorbs the heat of Q _12, fully closed the main fuel line 12a, when fully bypasses the superheater 12 is fully opened and 12b is endothermic situation of Figure 3. Since the inlet gas temperature of the reactor 11 rises from T ₂ to T ₁ , a temperature rise q ₁₁ is added in the reactor ₁₁ and the endothermic amount in the reactor increases to Q ₁₁ ′. The reaction temperature of can be secured. The reactor bypass line 13 is used when the reactor temperature is lower than specified at the initial stage of equipment start / stop, etc., to reduce thermal cycle fatigue of the reaction catalyst and maintain its life. In the case of stopping, the reactor bypass line 13 is opened, and at the same time, the reactor 11 is filled with an inert gas. Reactor bypass line 13
During use, the gas turbine 2 is operated with the evaporated fuel.

Fig. 4 shows the basic structure of the fuel evaporation system.
The reactor 11 and the heater 10 shown in FIG. 1 are omitted, and by doing so, auxiliary equipment is reduced as compared with FIG. 1, so that the cost is further reduced and the arrangement of each device is facilitated.

FIG. 5 shows an application example of the fuel processing system.
(1) is an example corresponding to FIG. 1, and (4) is an example corresponding to FIG. The (2) examples provided as merging duct 7a ₂ divides the fuel preheater 7a from 7a _1, (3) is an example in which the reactor side by dividing the feed water preheating of boiler unit 3.

Although it is the basis of the present invention to use the exhaust duct in two branches, the arrangement of FIG. 6 is conceivable. That is, in (1), when the ducts are joined together, the number of exhaust ducts can be one, which is advantageous for routing the ducts. Exhaust gas control to the reactor 11 is performed by the flow rate control damper (R) 8b, and the flow rate control damper (R) that is interlocked with it
Adjust the airflow at the merging section at 8c and 8d.

In (2) and (3), when connecting the exhaust duct to the chimney as it is, the shut-off damper 8 is installed on both the outlet side of the reactor 11 and the boiler outlet side.
c and 8d are arranged. In this case, the shut-off dampers 8c and 8d are for closing the draft while the equipment is stopped, and the equipment can be simplified as compared with (1), but the amount of routing of the exhaust duct is required twice.

According to the embodiment described above, the following effects can be obtained.

(1) As shown in FIG. 1, since the catalyst is incorporated only in the reactor 11 that carries out the chemical endotherm, the endothermic planning is easier and the amount of the catalyst is smaller than that of the conventional one. Equipment costs are low.

(2) The structure of the reactor 11 (fuel vaporizer 7b in FIG. 7) side may be replaced by a superheater 12 / reactor 11 / heater 10 / evaporator 8 / preheater 7a as shown in FIG. 4 Superheater 12
Since / Evaporator 9 / Preheater 7a is used, physical endotherm is performed by the chemical endotherm or other in the reactor 11, and the heat quantity of the fuel a can be increased. Higher efficiency of combined power generation system can be obtained.

Methanol decomposition reaction or steam reforming reaction is a reaction for carrying out the above chemical endotherm, but these reactions can be realized if the catalyst and its reaction temperature are set to predetermined values as in the above-mentioned embodiment. On the other hand, when the latent heat of vaporization is large, the combined power generation efficiency is improved as compared with the simple use with liquid fuel even if the retained heat amount is improved only by the physical heat absorption of the latent heat and sensible heat. Although the degree of improvement is lower than that in the case of using the reaction endotherm, it is beneficial because the equipment cost is low.

(3) Since the superheater bypass line 12b is provided between the superheater 12 and the combustor 1 of the gas turbine power generation system 2 , by raising the temperature of the reactor 11, deterioration of the performance of the reaction catalyst can be suppressed. That is, since the superheater bypass line 12b acts to reduce the amount of heat absorbed by the superheater 12 when the performance of the reaction catalyst is lowered as shown in FIGS. 2 and 3, the “reactor for maintaining reaction efficiency” It is effective for improving the ambient gas temperature.

(4) The reactor bypass line 13 provided between the reactor 11 and the superheater 12 is used when the reactor 11 cannot be used due to pulverization of the reaction catalyst, damage to the reactor 11, or the plant ( In other words, when the gas turbine) has a low load and the reactor temperature falls below a specified value, and when "a sudden transient operation (starting / stopping), the temperature of the fuel vapor fed into the reactor 11 changes significantly. Lowers catalyst performance and life. "
It can be effectively used for preventing such a situation.

The method of constructing the combined power generation system according to the present invention described above is an example, and the gas turbine exhaust heat recovery technique of the present invention can be applied to all systems using a gas turbine and generated steam.

Since the configuration of the combined power generation system is generally used, it can be applied to both (a) uniaxial type and (b) multiaxial type.

In addition, the steam pressure (single pressure, double pressure, reheat), etc., can be used in any manner depending on the steam turbine used.

Furthermore, the steam that drives the steam turbine in the combined cycle power generation system can be separately injected into the turbine inlet of the gas turbine to recover the power.

In short, the present invention can be applied to any system as long as it has a technical idea of recovering the exhaust heat of the gas turbine and a technical idea of generating steam by the residual exhaust heat used for the chemical reaction endotherm of methanol.

〔The invention's effect〕

According to the present invention described above, since the catalyst is incorporated only in the reactor that performs the chemical endotherm, the amount of the catalyst is smaller than that of the conventional one, and thus the combined power generation cost is low. System can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the combined power generation system of the present invention, FIGS. 2 and 3 are diagrams for explaining the action and effect of FIG. 1, and FIG. 4 is a modification of FIG. Fig. 5 is a schematic configuration diagram showing an example, Fig. 5 is a diagram showing an application example of the fuel processing system of the present invention, Fig. 6 is a diagram showing an application example of the exhaust duct division of the present invention, and Fig. 7 is a conventional combined power generation system. It is a schematic block diagram which shows an example. 1 ...... combustor, 2 ...... gas turbine power generation system, 2a ...... gas turbine, 2b ...... generator, 2c ...... air compressor, 3 ...... waste heat boiler system, 3a ...... exhaust main pipe, 4 ... … Steam turbine power generation system, 4a …… Steam turbine, 4b …… Generator, 5 …… Condenser, 7a …… Fuel preheater, 8a …… Exhaust branch pipe, 8b, 8c ……
Branch duct inlet, outlet damper, 9 ... Evaporator, 10 ... Heater, 11 ... Reactor, 12 ... Superheater.

Claims (1)

(57) [Claims] 1. A gas turbine power generation system, an exhaust main for circulating high temperature exhaust gas from the gas turbine power generation system, and an upstream end and a downstream end of the exhaust main connected to each other. An exhaust branch pipe, dampers that are respectively arranged on the inlet side and the outlet side of the exhaust branch pipe to adjust the flow rate of the exhaust gas, and are arranged between the inlet and the outlet of the exhaust branch pipe in the exhaust main pipe. A steam turbine power generation system driven by high-pressure steam, and a fuel preheating for preheating fuel disposed in the exhaust branch pipe and supplied to the gas turbine power generation system with heat energy of exhaust gas flowing through the exhaust branch pipe And an evaporator for evaporating the fuel preheated by the fuel preheater, and a fuel vapor which is disposed between the inlet and the outlet of the exhaust branch pipe and chemically reacts the fuel vapor vaporized by the evaporator. Fuel energy Combined power generation, comprising: a reactor having a catalyst for converting secondary fuel with high Rugi, and a superheater that superheats the secondary fuel from the reactor and supplies it to the gas turbine power generation system. system.