JPS63290301A - Exhaust-heat recovery boiler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial use!!?) The present invention is used in a gas turbine cogeneration system, and is an exhaust heat recovery boiler that recovers exhaust gas heat from a gas turbine. This is related to the improvement of.

(Conventional technology) Combination of gas turbine power generation equipment and exhaust heat recovery boiler 1.
Various system configurations have been proposed for combined heat and power generation equipment that simultaneously supplies electrical energy and steam energy. Figure 3 shows a typical example, in which high-pressure combustion air pressurized by compressor
into the gas turbine 3, inject the fuel F into this to generate high-temperature, high-pressure combustion gas, and supply this into the gas turbine 3,
The power of the rotating shaft rotates the generator 5 via the speed reduction device 4 . The exhaust gas G from the gas turbine 3 is sent to the exhaust heat recovery boiler C through the exhaust gas duct 7.
After the heat is recovered by the economizer 9 or the like, it is discharged into the atmosphere from the chimney 10.

On the other hand, if it is necessary to increase the amount of steam generated by the exhaust heat recovery boiler C due to a request from the steam load side, the auxiliary combustion device 11
is activated, and burner auxiliary combustion is performed using exhaust gas G as a substitute for combustion air. In addition, about 15% of 02 remains in the exhaust gas G from the gas turbine 3, and the dust content is relatively small at about 0.05 fr/Nm', so it can be fully utilized as auxiliary combustion air. .

Conversely, if a certain electrical output is required but only a small amount of steam generation is required, the opening degrees of the dampers 12 and 13 are controlled, and the excess exhaust gas G is passed through the bypass line 14 to the bypass chimney 15. into the atmosphere.

By the way, the exhaust gas temperature from the gas turbine 3 is about 5
00°C, which typically contains about 250 ppm (
The combustor 2 contains low NOx such as steam injection or water injection.
Even when x countermeasures are taken, approximately 1100 pp of NOx still exists. Therefore, in cases where pollution regulations are strict, a denitrification device is installed in the exhaust gas G line to further reduce NOx.
Normally, a catalytic cyclic type dry denitrification device 16 that uses ammonia as a cyclic gas is built into the exhaust heat recovery boiler rod, thereby removing NOx.

The dry denitrification device 16 uniformly mixes ammonia gas (NH3) into the exhaust gas G and passes it through the catalyst layer to perform the so-called NOx reduction reaction (reaction temperature: approx.
00 to 400℃) to decompose and remove NOx, and in order to increase the denitrification efficiency, 4 NHs + 4
NO+ 02 →4 Nx + 6 HsO8N
Hz + 6 N (h → 7 Ng +
It is an essential requirement to maintain the 12 HzO exhaust gas temperature at about 300°C to 400°C.

However, in the conventional exhaust heat recovery boiler of combined heat and power generation equipment, when the auxiliary combustion device 11 is operated to increase the amount of steam generated salt, the temperature of the exhaust gas flowing into the dry denitrification device fluctuates greatly. However, there is a problem that the denitrification efficiency is significantly deteriorated.

Conversely, in order to suppress the amount of steam generated, excess exhaust gas G
If the exhaust gas is discharged from a bypass chimney, untreated exhaust gas will be released, causing problems such as environmental pollution.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems in conventional combined heat and power generation equipment using gas turbines. temperature fluctuates greatly,
This is intended to solve problems such as denitrification efficiency tends to deteriorate, and when the amount of (O) steam generated is suppressed, untreated exhaust gas emissions 1 increase, which tends to cause environmental pollution. Even when performing auxiliary combustion as a substitute for combustion air, or when reducing only the amount of steam generated on the exhaust heat recovery boiler side, the temperature of the exhaust gas flowing into the denitrification equipment is always maintained within the optimal range. It is an object of the present invention to provide an exhaust heat recovery boiler that is capable of denitrating all exhaust gas from a gas turbine at all times.

(Means for Solving the Problems) The first invention provides a heat recovery boiler for a combined heat and power generation facility using a gas turbine.
A dry denitrification device is installed between the secondary evaporator and the secondary evaporator,
A bypass duct for exhaust gas is provided in the primary evaporator, and a damper device is provided on the inlet side of the primary evaporator and in the bypass duct, the opening and closing of which is controlled by a gas temperature control device, respectively.
The basic structure of the invention is to control the temperature of the exhaust gas at the inlet side of the dry denitrification device to a predetermined value by adjusting the bypass pattern of the exhaust gas.

In addition, the second invention of the present invention provides a dry denitrification device between a primary evaporator and a secondary evaporator that form a boiler heat transfer section in an exhaust heat recovery boiler of a combined heat and power generation facility using a gas turbine. A bypass duct for exhaust gas is provided in each of the primary evaporator and the secondary evaporator, and the opening and closing of the primary evaporator inlet side and the primary evaporator bypass duct are respectively controlled by a gas temperature control device. A damper device is provided on the inlet side of the secondary evaporator and a bypass duct of the secondary evaporator, each of which is controlled to be closed by a steam load control device, and a damper device is provided on the inlet side of the secondary evaporator and a bypass duct of the secondary evaporator, respectively, and the damper device is controlled to be closed once by a vapor load control device. The amount of exhaust gas in the bypass duct is adjusted to control the exhaust gas temperature on the inlet side of the dry denitrification equipment to a predetermined value, and the steam load control device adjusts the amount of exhaust gas in the bypass duct of the secondary evaporator and the operation of the auxiliary combustion device. The basic structure of the invention is to control the amount of steam to a predetermined value.

(Function) Exhaust gas from the gas turbine passes through the exhaust gas duct.
After being sent to the next evaporator and treated with a dry denitrification device,
Heat is recovered in the secondary evaporator and economizer, and then exhausted to the outside through the chimney.

The exhaust gas temperature at the inlet side of the dry denitrification device is detected by a temperature detector and input to the gas temperature control device. The gas temperature control device sends an open/close control signal to the damper device, thereby adjusting the amount of exhaust gas flowing through the bypass duct of the primary evaporator (that is, the amount of exhaust gas flowing through the primary evaporator). As a result, the temperature of the exhaust gas flowing into the denitrification device is maintained immediately after setting.

On the other hand, the steam pressure in the main steam pipe is detected by a pressure detection device and input to the steam load control device. A control signal is sent from the steam load control device to the damper device and the auxiliary fuel control valve, and the amount of exhaust gas flowing through the bypass duct of the secondary steam generator (i.e., the amount of exhaust gas flowing through the secondary evaporator 9 economizer, etc.) By controlling the amount of steam generated) and the operation of the auxiliary combustion device, the amount of steam generated can be controlled in accordance with the desired steam load.

In addition, the water supply is naturally circulated to the secondary steam generator through the air-water drum, downcomer pipe, water drum, etc., and the water supply is forcibly circulated from the air-water drum to the primary evaporator by a circulation pump. .

(Example) Hereinafter, the present invention will be explained in detail based on FIGS. 1 and 2. Incidentally, parts common to those in FIG. 3 are given the same reference numerals.

FIG. 1 is a system outline diagram of a cogeneration power generation facility to which the waste heat recovery boiler according to the present invention is applied, and the cogeneration power generation facility A
is constructed by connecting a gas turbine power generation device B and an exhaust heat recovery boiler C via an exhaust gas duct 7.

The gas turbine power generation equipment B includes an air compressor 1 and a combustor 2.
, a gas turbine 3, a reduction gear 4, a generator 5, etc.

Further, the exhaust gas duct 7 is provided with an auxiliary combustion device 11, in which exhaust gas from the gas turbine 3 is used as a substitute for combustion air, and a combustion auxiliary material F such as kerosene is combusted in a burner.

On the other hand, the exhaust heat recovery boiler C is formed by arranging a primary evaporator 17, a dry denitrification device 16, a secondary evaporator 18, a carbon saver 9, etc. from the upstream side to the downstream side of the exhaust gas G. The primary evaporator 17 is provided with a bypass duct 19 for exhaust gas G, and the secondary evaporator 18 is provided with a bypass duct 20 for exhaust gas G.

In this embodiment, the end of the bypass duct 20 for the primary evaporator 18 is connected to the downstream side of the economizer 9, but this is connected to the upstream side of the economizer 9. Alternatively, a superheater (not shown) may be provided upstream of the exhaust gas of the primary evaporator 17.

Further, in this embodiment, the auxiliary combustion device 11 is configured by a so-called induct burner that provides an auxiliary combustion burner in the exhaust gas duct and uses the exhaust gas G as a substitute for combustion air, but the auxiliary combustion device 11 may have any configuration. Of course, it is possible.

The secondary evaporator 18 employs a so-called natural circulation water supply system, and by connecting the air-water drum 21 and the water drum 22 with a group of downcomer pipes 23, the air-water drum 21
A natural circulation path is formed in the following order: -> downpipe 23 -> water drum 22 -> secondary evaporator I8 - air/water drum 21.

Furthermore, the primary evaporator employs a so-called forced circulation type water supply system, and water is supplied from the air/water drum 21 through a circulation pipe 24 by a forced circulation pump 25 .

The dry denitrification device 16 employs a so-called dry catalytic reduction method in which ammonia gas is used as a reducing gas, and NOx is decomposed and removed by uniformly mixing this into the exhaust gas G and passing it through a catalyst layer. A denitrification device according to the above is used, and the allowable temperature limit of the catalyst layer is 420° to 430°C, and the optimum temperature for the reduction reaction is 300 to 400°C. Further, it goes without saying that the denitrification device 16 may have any structure as long as it is a dry type denitrification device.

In FIG. 1, 26 is a damper device installed on the exhaust gas inlet side of the primary evaporator 17, and 27 is a bypass tact 19.
28 is a damper device installed on the exhaust gas inlet side of the secondary evaporator 18, 29 is a bypass duct 2
This is a damper device installed at 0.

Further, (9) is a gas temperature control device, which is a dry denitrification device 1.
The temperature of the exhaust gas G at the inlet side of the denitrification device 16 is input from the temperature detector 31 provided at the inlet side of the denitrification device 16, and the opening/closing drive signals of the damper devices 26 and 26 are sent to the respective damper drive devices ( (not shown).

Furthermore, 32 is a steam load control device, which inputs the steam pressure in the main steam pipe from a steam pressure detection screen provided on the main steam pipe vane, and also sends an opening/closing drive signal to the damper device 28. Open/close control signals to the auxiliary fuel adjustment valve 35 are output, respectively.

Next, the operation of the exhaust heat recovery boiler C will be explained.

The exhaust gas G discharged from the gas turbine 3 through the exhaust gas duct 7 has a temperature of approximately 500°C and a NOx level of 11°C and approximately 250p.
pm (kerosene fuel, 024% conversion value), primary evaporator 17, dry denitrification device 16, secondary evaporator 18 and energy saver 9
It passes through the chimney 10 and is discharged to the outside.

The exhaust gas temperature at the inlet side of the dry type denitrification device 16 is set at approximately 380 to 400°C from the viewpoint of denitrification efficiency, and the gas temperature control device ( Both damper devices 26 and 27 are opened and
Closed controlled.

The exhaust gas G that has passed through the primary evaporator 17 and bypass duct 19 is denitrated to a desired NOx concentration in the denitrification device 16, cooled to approximately 180 to 190°C in the secondary evaporator 18, and further passed through the energy saver 9. After being cooled down, it is dissipated into the atmosphere.

When the steam load increases or decreases and the steam pressure in the main steam pipe 33 fluctuates, the steam load control device 32 controls the opening and closing of both damper devices 4 and 29, starts and stops the auxiliary combustion device 11, and adjusts the fuel. The opening and closing of the valve 35 is controlled to generate an amount of steam commensurate with the steam load.

The heat transfer area ratio of the primary evaporator 17 and the secondary evaporator 18 is
Gas turbine exhaust gas fi: 4QOOON door/H,
Exhaust gas temperature: SOO°C, exhaust gas temperature at primary evaporator outlet: 380°C, exhaust gas temperature at secondary evaporator outlet = 185°C.

The pressure of the air-water drum is determined under the conditions of yKy/crilc, as shown in the table below.

That is, the exhaust gas temperature in the denitrification device 16 is set to the optimum range 38.
In order to achieve a temperature of 0° to 390°C, it is necessary to install a primary evaporator corresponding to approximately 12% of the total heat transfer area upstream of the denitrification device 16, and the amount of heat absorbed by the primary evaporator is approximately 12% of the total heat transfer area. becomes.

Therefore, by adopting a combination system in which the primary evaporator 17 is a forced circulation type and the secondary evaporator is a natural circulation type, the capacity of the forced circulation pump 25 can be reduced, the required power is reduced, and the air-water drum This provides advantages such as the ability to omit the steel frame that supports the equipment.

FIG. 2 is a system diagram of a waste heat recovery boiler according to a second embodiment of the present invention, in which a primary evaporator 17 and a secondary evaporator 18
The entire structure is a forced circulation type. In other words, forced? ! This embodiment differs from the first embodiment in that the ring pump 25 forcedly circulates the water flowing through both evaporators 17 and 18, and the other configurations are the same.

(Effect of the invention) In the first invention, a dry denitrification device is provided between the primary evaporator and the secondary evaporator, a bypass duct is provided in the primary evaporator, and the damper device of the primary evaporator system is Since it is configured to open and close using a temperature control device, by adjusting the amount of exhaust gas flowing through the bypass duct, the temperature of the exhaust gas flowing into the dry denitrification equipment can always be kept within the optimum temperature range for the denitrification reaction. . As a result, it becomes possible to denitrate the entire amount of exhaust gas with high efficiency under a wide range of power loads and steam loads.

Further, in the second invention of the present invention, in addition to controlling the exhaust gas temperature, a bypass duct is provided in the secondary evaporator, and the damper device of the secondary evaporator system and the fuel adjustment valve of the auxiliary combustion device are controlled by the steam load control device. Because of this configuration, the power generation device side can control the amount of steam generation over a wide range corresponding to the steam load side while controlling the operation according to the electric power demand.

As mentioned above, the present invention significantly improves the operational flexibility of cogeneration power generation equipment, enables a wide range of load operation across both electric power load and steam load, and efficiently denitrates the entire amount of exhaust gas. It has excellent practical utility.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram of a cogeneration power generation facility to which the exhaust heat recovery boiler according to the present invention is applied. FIG. 2 is a system schematic diagram of the exhaust heat recovery boiler according to the second embodiment. FIG. 3 is a schematic diagram of a cogeneration power generation facility using a conventional gas turbine. A Combined heat generation equipment B Gas turbine power generation equipment C Exhaust heat recovery boiler G Exhaust gas 7 Exhaust gas duct 16 Dry denitrification device 17 Primary evaporator 18 Secondary evaporator 19 Primary evaporator bypass duct 20 Secondary evaporator bypass duct 26.27 Damper device 28.29 Damper device 30 Gas temperature control device 32 Steam load control device procedure amendment (voluntary) 1. Indication of the case: Japanese Patent Application No. 124969/1988 2, Title of the invention
Exhaust heat recovery boiler 8, relationship with the amended case Patent applicant address 1-3-23 Dojimahama, Kita-ku, Osaka Name Tarima Co., Ltd. Representative Fuku 1) Jun Yoshi 4, Agent 5, Number of inventions increased by amendment 1)
The specification is amended as follows. (2) Replace No. 1rgJ attached to the application with the attached Figure 1.

Claims (4)

[Claims] (1) In the exhaust heat recovery boiler of cogeneration power generation equipment using a gas turbine, the primary evaporator (
A dry denitrification device (17) and a secondary evaporator (18) are installed.
6), and exhaust gas (G) is provided in the primary evaporator (17).
damper devices (26), (27) which are controlled to open and close by a gas temperature control device (30) are provided on the inlet side of the primary evaporator (17) and the bypass duct (19). The dry denitrification device (16) can be
An exhaust heat recovery boiler configured to control the temperature of exhaust gas (G) flowing into the boiler to a predetermined value. (2) In the exhaust heat recovery boiler of cogeneration power generation equipment using a gas turbine, the primary evaporator (17) and the secondary evaporator (1
A dry denitrification device (16) is installed between 8), and bypass ducts (19) and (20) for exhaust gas (G) are provided between the primary evaporator (17) and the secondary evaporator (18), respectively. In addition, the inlet side of the primary evaporator (17) and the primary evaporator (17)
A gas temperature control device (3) is installed in each bypass duct (19).
damper device (26), (
27), and a damper device that is controlled to open and close by a steam load control device (32) on the inlet side of the secondary evaporator (18) and a bypass duct (20) of the secondary evaporator (18), respectively. (28) and (29) are provided, and the amount of exhaust gas in the bypass duct (19) of the primary evaporator (17) is adjusted by the gas temperature control device (30), and the amount of exhaust gas ( G) is controlled to a predetermined value, and the steam load control device (32) adjusts the amount of exhaust gas in the bypass duct (20) of the secondary evaporator 4 and the operation of the auxiliary combustion device (11) to reduce the amount of steam generated. An exhaust heat recovery boiler configured to control to a desired value. (3) The exhaust heat recovery boiler according to claim 2, wherein the auxiliary combustion device (11) is a combustion burner provided in the exhaust gas duct (7) upstream of the primary evaporator (17). (4) The exhaust gas according to claim 2, wherein the secondary evaporator (18) is a natural circulation type evaporator for the feed water, and the primary evaporator (17) is a forced circulation type evaporator for the feed water. Heat recovery boiler.