JPS58143826A - Denitration apparatus assembled with waste heat boiler - Google Patents

Abstract

PURPOSE:To provide a denitration apparatus remarkably enhanced in the mixing effect of a reducing agent and capable of enhancing denitration efficiency without enlarging and complicating said apparatus, constituted by using a silencer provided to the downstream side of a gas turbine in combination with a reducing agent pouring apparatus. CONSTITUTION:After NH3 is poured in an exhaust gas G exhausted from a gas turbine apparatus 12 by an NH3 pouring apparatus 10 provided to the cross area of a gas turbine oultet flue 11, the NH3 containing exhaust gas G is passed through a silencer 2 provided to the downstream side thereof. Subsequently, the NH3 containing exhaust gas passed through the silencer 2 is sent to the superheater 3 and the pipe group 4A of a high temp. evaporator 4 of a waste heat boiler 1 and, after NH3 is sufficiently mixed herein, introduced into a reactor 7 to carry out denitration reaction while the exhaust gas wherein NOx is decomposed to harmless N2 and H2O by reduction is exhausted to the atmosphere through a low temp. evaporator 4B and a coal economizer 5. On the other hand, in the boiler 1, steam discharged from the evaporator 4 and heated in the superheater 3 is sent to a steam turbine apparatus 13 to operate the same. In this case, water is supplied to the coal economizer 5 from the apparatus 13 through an introducing line 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a denitrification device built into a waste heat boiler, and more particularly to a four-way denitrification device built into a waste heat boiler, which is provided on the downstream side of an output flue of a gas turbine.

One of the methods for removing nitrogen oxides (NOx) from exhaust gas is to spray a reducing agent such as ammonia (NH3) (hereinafter referred to as ammonia) into 4'IP gas and use a catalyst-filled denitrification method. A method is known in which NO in exhaust gas is decomposed into harmless N2 and N20 by passing it through a reactor. In order to carry out this method, if a waste heat boiler is installed in the flue, for example, a reactor filled with a catalyst is placed between the high temperature evaporator and the low temperature evaporator of the waste heat boiler. An ammonia injector was installed just in front of it.

However, in such an apparatus configuration, there is a problem that ammonia cannot be sufficiently uniformly mixed into the exhaust gas, so that the reaction within the denitrification reactor becomes insufficient and unreacted ammonia is discharged.

To solve the above problem, for example, there is a method of placing a mixer for stirring the exhaust gas upstream of the reactor, but it has the disadvantage that the equipment is complicated and expensive. Since the superficial velocity of the boiler exhaust gas is about 8 m/z, which is about 1/2 of the superficial velocity of the normal boiler flue gas, there is a problem that it becomes more difficult to mix ammonia in a short time. Furthermore, in recent years, efforts have been made to improve the efficiency of flue gas denitrification, and the aim is to suppress the emission of unreacted ammonia as much as possible, making it necessary to lengthen the mixing distance and increase the number of ammonia nozzles. In order to increase the denitrification efficiency, it was necessary to make the equipment larger and more complex.

On the other hand, in order to prevent noise from the gas turbine, a silencer is installed at the exit flue of a gas turbine, consisting of a number of sound-absorbing panels arranged in parallel with the gas flow. However, no attempt has been made to utilize it effectively for other purposes.

The object of the present invention is to effectively utilize the silencer of the exhaust gas flue of a gas turbine in a denitrification device built into a waste heat boiler installed on the downstream side of the exit flue of the gas turbine, in view of the prior art described in section 2. It is an object of the present invention to provide a denitrification device that can significantly enhance the mixing effect of agents and increase the denitrification efficiency without making the device bulky or complicated.

In order to improve the mixing of the reducing agent such as ammonia sprayed into the exhaust gas, the present invention aims to change the injection position of the reducing agent such as ammonia to the upstream part of the silencer of the gas turbine outlet flue where the gas flow rate is high, for example, upstream of the Xylenzer. It is installed on the side, at the tip of the sound-absorbing panel of the silencer, or upstream between the sound-absorbing panels.

In the present invention, the denitrification reactor incorporated into the waste heat boiler is installed at an appropriate position in the waste heat boiler depending on the optimum operating temperature of the catalyst used, for example, between the high humidity evaporator and the low temperature evaporator, between the superheater and the high temperature It can be placed between the evaporator or between the low temperature evaporator and the economizer.

In the present invention, the exhaust gas is well agitated by the silencer, which enhances the agitation effect, and by the waste heat boiler's superheater, evaporator, and other tube groups, and the denitrification efficiency is further improved.

An embodiment of the present invention will be described below with reference to the drawings.

The device system shown in FIG. 1 includes a gas turbine device 12 to which fuel F and air A are supplied, and a gas turbine outlet flue 1.
1, a waste heat boiler 1 provided downstream of a flue 11, a denitrification reactor 7 provided therein, and a chimney 6. The ammonia injection device fM'lO, which is a reducing agent, is installed upstream of the siren boo 2 in the gas turbine outlet flue 11 that guides the exhaust gas G from the gas turbine device 7112 to the waste heat boiler 1. Figure 2 shows
This installation state is shown as a model, in which a large number of sound absorbing panels 2A are arranged in parallel to the gas flow G in the flue 11, and an ammonia injection pipe 1()A is placed in the upstream part of the gas passage between the panels.
is provided.

On the other hand, the reactor 7 filled with the catalyst is placed at an appropriate position in the waste heat boiler 1 depending on the optimum operating temperature of the catalyst.
In the case shown, the still temperature evaporator 4 is located upstream of the gas flow.
A and the low temperature evaporator 4B located on the downstream side. The waste heat boiler 1 includes a superheater 3, a steam pipe 8, a steam turbine device 13, a water supply pipe 9, and a energy saver 9 in addition to evaporators 4.4A and 4B.

In the above device, the exhaust gas G at about 550° C. discharged from the gas turbine device 2 is transferred to the gas turbine outlet flue 11.
Ammonia is injected by an ammonia injection device 1° having a large number of ammonia injection nozzles installed in the cross section of the pipe, and then passes through a silencer 2 in the wake. The gas turbine outlet flue 11 has an exhaust gas flow velocity of 1 to that of a normal flue.
The speed is as high as 5 to 20 m/s, and the exhaust gas G is accelerated and decelerated when passing through the silencer, and further produces vortices and turbulence, so the exhaust gas is mixed well and ammonia is uniformly mixed into the exhaust gas. The exhaust gas containing ammonia after passing through the silancer 2 reaches the superheater 3 of the waste heat boiler 1 and the tube group of the high-temperature evaporator 4A, and due to the vortices and turbulence generated here, ammonia is sufficiently mixed into the exhaust gas. After being combined, they are introduced into a reactor 7 where a denitrification reaction is carried out. The exhaust gas which is reduced and decomposed by the reactor 7 into harmless N2 and N20 is subjected to low-temperature evaporation Xi+4B and the economizer 5.
It is then discharged into the atmosphere from the chimney 6.

On the other hand, in the waste heat boiler 1, steam released from the evaporator 4 and heated in the superheater 3 passes through the steam pipe 8 to the steam turbine device 13, and operates the steam turbine device 13. Water is introduced from the device 13 into the energy saver 5 via the water supply pipe 9.

In the present invention, the xylenzer installed at the gas turbine outlet is of a sound-absorbing type, typically one in which a predetermined number of two sound-absorbing nozzles are arranged in the flue in parallel with the gas flow. In FIG. 2, a predetermined number of ammonia injection pipes 10A (not particularly related to the number of two panels) are arranged at equal intervals perpendicular to the gas flow in the first stream of this panel 2A.

In this case, the distance between the ammonia injection pipe 10A and the tips of the two sound-absorbing panels may be maintained to such an extent that the ammonia gas jet from the ammonia injection nozzle is not affected by the two sound-absorbing panels. Note that the shape of the two sound-absorbing panels does not necessarily have to be flat, as long as it divides the gas flow and gives a stirring effect (for example, it may have a honeycomb shape).

Next, FIGS. 3 and 4 show other embodiments of the arrangement of the silencer and the ammonia injection tube used in the present invention. FIG. and the nozzles are arranged so that ammonia is injected on both sides perpendicular to the exhaust gas flow. Further, in FIG. 4, an ammonia injection pipe 10A is provided at the gas control inflow section (preferably on the upstream side) between the sound absorbing panels 2A.

In any of the above embodiments, a good mixing effect of exhaust gas and ammonia can be obtained. Note that the positional relationships shown in the above embodiments do not necessarily specify the number of injection pipes IOA or the number of sound absorbing panels 2A, and also the number of 7y monia injection nozzles of the ammonia injection pipe 1()A and its It does not limit the direction of spraying.

In the present invention, the mixing effect of exhaust gas and ammonia is further enhanced by incorporating the waste heat boiler into the denitrification reactor, but the position of the denitrification reactor in the waste heat boiler is determined by the optimum catalyst in the reactor. Determined by operating temperature. For example, in FIG. 1, the reactor 7 is placed between the high-temperature evaporator 4A and the low-temperature evaporator 4B.
This is because approximately 300° C.) is equal to the exhaust gas temperature at the position. Further, when the optimal operating temperature of the catalyst is about 300° C., it is desirable to arrange the reactor 7 between the low temperature evaporator 4B and the economizer 5, whose exhaust gas temperature is about this temperature. Further, when the optimum operating temperature of the catalyst is about 450° C., it is desirable that the reactor 7 be located between the superheater 3 and the high-temperature evaporator 4A.

As described above, according to the present invention, by using the silencer on the downstream side of the gas turbine in combination with the reducing agent (ammonia) injection device, the distance (residence time) between the injection device and the reactor is increased, (9) By using the sound absorbing panels of the silencer and the tube group of the waste heat boiler, the reducing agent can be sufficiently mixed into the exhaust gas. Therefore, there is no need to provide a special mixer, and the equipment can be simplified and further downsized.In addition, the reducing agent is mixed well and reacts sufficiently with NOx in the exhaust gas, so injection is possible. The amount of reducing agent to be used can be kept to the minimum necessary, making it economical and eliminating the possibility that unreacted reducing agent will be included in the exhaust gas released into the atmosphere.
There is no need to worry about secondary pollution. Furthermore, since the silencer installation duct of the gas turbine outlet flue has a smaller cross-sectional area than the subsequent duct, various effects can be achieved, such as the ability to downsize and simplify the installed injection device.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a denitrification device built into a waste heat boiler installed in a gas turbine, and FIGS. 2, 3, and 4 show various arrangement examples of the silencer and ammonia injection device in the present invention, respectively. FIG. 1... Waste heat boiler, 2... Silencer, 2A...
・Suction (10) Sound panel, 4... Evaporator, 4A... High temperature evaporator, 4
B...Low temperature evaporator, 6...Chimney, 7...Denitration reactor, 10...Ammonia injection device ft, 10A...
Ammonia injection pipe, 11... gas turbine outlet flue,
12... Gas turbine device t. Agent Patent Attorney Takeshi Kawakita (11) 136

Claims (1)

[Scope of Claims] (1) A silencer with a built-in sound-absorbing panel installed in the outlet flue of the gas turbine, and a waste heat boiler installed in the flue with a larger diameter than the flue on the downstream side. A denitrification device built into a waste heat boiler, comprising: a denitrification reactor built into the waste heat boiler; and a reducing agent injection means provided upstream of the sound absorption bar 44 of the silencer. (2. A denitrification device built into a waste heat boiler, characterized in that the denitrification reactor in the waste heat boiler is located between a high temperature evaporator and a low temperature evaporator in claim 1. (3) Patent Claim 1: A denitrification device incorporated into a waste heat boiler, characterized in that the denitrification reactor is located between a superheater and a high-temperature evaporator. (4) Claim 1: A denitrification device incorporating a waste heat boiler, characterized in that the denitrification reactor is located between a low-temperature evaporator and a carbon saver.