JPS62202902A - Exhaust heat recovery boiler equipment - 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 Field of Application] The present invention relates to an exhaust heat recovery boiler device that uses combustion exhaust gas from a gas turbine or diesel engine as a heat source gas, and more specifically, the present invention relates to an exhaust heat recovery boiler device that uses combustion exhaust gas from a gas turbine or diesel engine as a heat source gas. The present invention relates to an exhaust heat recovery boiler device equipped with a reactor having a catalyst layer that is removed by reductive decomposition.

[Prior Art] In an exhaust heat recovery boiler device that uses combustion exhaust gas from a gas turbine or diesel engine as a heat source gas, a superheater, an evaporator, and a carbon saver are normally installed in order from the upstream side to the downstream side of the combustion exhaust gas flow. It is equipped with The feed water led to the energy saver via the water supply pipe is preheated here, vaporized in the generator, and further heated in the superheater to become superheated steam. Then, for example, it is introduced into a steam turbine device through steam piping, and drives the steam turbine device and a generator.

By the way, in order to remove nitrogen oxides (N2O) from the combustion exhaust gas, it is widely practiced to install a denitrification device in this exhaust heat recovery boiler device, but as one of the denitrification reactors, It is known to have a catalyst layer that blows ammonia or hydrazine (usually ammonia) into the exhaust gas to remove NOx by catalytic reductive decomposition.

As shown in FIG. 3, such a denitrification reactor normally achieves its optimum denitrification efficiency at 330°C to 400'C.

Therefore, the temperature of the combustion exhaust gas from a gas turbine or diesel engine fluctuates significantly depending on the load condition of these engines, and the gas salt introduced into the denitrification reactor may exceed the above-mentioned optimum range, and furthermore, the reactor may be damaged by heat. Temperatures can reach temperatures that cause

Therefore, it was proposed that a denitrification reactor be installed between the W1 coalizer and the evaporator of the exhaust heat recovery boiler device (Special Publications Publication No. 6).
O-9201).

[Problems to be Solved by the Invention] However, in the exhaust heat recovery boiler device described in Japanese Patent Publication No. 60-9201, only one evaporator is installed, and the denitrification reactor is installed on the outlet side of this single evaporator. Due to the fact that the denitrification reactor is provided with a denitrification reactor, it is not possible to freely adjust only the temperature of the gas introduced into the denitrification reactor, and operation with low denitrification efficiency is often forced.

In addition, as a result, unreacted reducing agents such as NH3 tend to leak to the latter stage, resulting in a loss of reducing agent, and when SOx gas is included in the combustion exhaust gas, NH4I
There is also the possibility that compounds such as SO4 may precipitate at the latter stage and cause trouble.

(Generally, N H4HS O4 in exhaust gas is approximately 230°
When the temperature is below C, it becomes a liquid phase and adheres to the surface of the device, causing various troubles. ) [Means for Solving the Problems] The exhaust heat recovery boiler device of the present invention is an exhaust heat recovery boiler device that introduces gas turbine or diesel engine combustion exhaust gas as a heat source. A superheater, a first evaporator, a denitrification reactor having a contact layer for removing nitrogen oxides in combustion exhaust gas by catalytic reductive decomposition, a second evaporator, and a carbon saver are sequentially provided, and the moderator Directing the heated feed water to the first and second evaporators.

Steam from at least one of these evaporators is guided to a superheater.

In addition, in this invention, you may provide a reheating burner in the upstream part of a superheater.

[Function] In the waste heat recovery boiler device of the present invention, the first evaporator is provided immediately downstream of the superheater, and the denitrification reactor is provided immediately downstream of the superheater. By adjusting the amount of heat exchange using means for adjusting pressure, the temperature at the inlet of the denitrification reactor can be controlled at an optimum temperature of 330 to 400°C.

In addition, as a result, it is possible to significantly reduce the loss of unreacted reducing agent (mainly NH3) leaking from the denitrification reactor to the downstream stage, and the loss of NH4H in the downstream evaporator, moderator, etc.
Precipitation of SO4'9 compounds can be suppressed, and troubles can be prevented from occurring.

Furthermore, since two evaporators are provided, sufficient heat recovery can be achieved by adjusting the amount of heat exchange between both evaporators.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a system diagram of an exhaust heat recovery boiler device according to an embodiment of the present invention, in which a gas turbine or a diesel engine
From the upstream side where the combustion exhaust gas flows, the over-ripener 2,
First evaporator3. A denitrification reactor 4 having a catalyst layer capable of removing nitrogen oxides in combustion exhaust gas by catalytic reductive decomposition, a second evaporator 5, and an fl:1 coalizer 6 are installed. Then, the supplied water heated by the economizer 6 is supplied to the first and second
Each device is connected by piping (not shown) so that the steam from at least one of these evaporators 3.5 (both in this example) is guided to the superheater 2. There is.

Furthermore, in the denitrification reactor 4, a reducing agent such as ammonia or hydrazine (in this example, ammonia or NH3) is blown into the combustion exhaust gas at the upstream side of the reactor 4, and this ammonia is The NOx components in the exhaust gas undergo a denitrification reaction when passing through the catalyst layer in the reactor 4. As is well known, this denitrification reaction produces NOx and NH
" reacts to produce N2 and N20.

Note that various catalysts such as iron oxide can be used as the catalyst.

With this configuration, the amount of heat exchanged in the first evaporator 3 is 21!11! By doing so, the inlet gas temperature of the denitrification reactor 4 can be controlled to an optimum temperature of 330°C to 400°C.

(For example, by increasing the steam pressure taken out from the first evaporator 3, the inlet gas temperature of the reactor 4 can be increased.) Furthermore, in the present invention, the upstream side of the denitrification reactor 4 By adding equipment such as connecting an air blowing pipe to the inlet gas, it is possible to quickly lower the gas temperature by introducing air when the inlet gas temperature rises to 400° C. or higher.

In addition, by setting the optimum reaction temperature of 330 to 400°C in this way, the denitrification reaction efficiency can be maintained at an extremely high level, thereby reducing the loss of unreacted reducing agent (mainly NH3) leaking from the denitrification reactor 4 to the subsequent stage. For example, the NHa content in the latter stage can be reduced to about 1 ppm or less.

Furthermore, since the leakage of undecomposed reducing agent to the downstream side is small, even if a small amount of sulfur oxide is present in the combustion exhaust gas, NH4HSO4 in the downstream evaporator and vJ coalizer, etc. The precipitation of the compound '4 can be suppressed,
Trouble can be prevented from occurring.

Note that in the present invention, at least a part of the reducing agent for denitration may be blown into the exhaust gas from the upstream side of the first evaporator 3. In this way, the mixing state of the reducing agent and the exhaust gas is improved. Therefore, more efficient denitrification can be performed.

Further, in the present invention, a reheating burner 7 may be provided upstream of the superheater 2, and it is preferable that the reheating burner 7 uses gas, low sulfur oil, or the like as fuel. When the reheating burner 7 is provided in this manner, in addition to the effect of the embodiment shown in FIG. 1, there is an effect that the temperature of the gas introduced into the denitrification reactor 4 can be adjusted more easily. That is, if the inlet gas temperature of the denitrification reactor 4 is lower than 330'O, by operating this reheating burner 7, the evaporation pressure of the first evaporator 3 is not changed, etc., and the inlet gas temperature is lower than 330'O. The gas temperature can be increased to 330°C or higher.

Further, when the reheating burner 7 is provided, even if the load of the gas turbine or diesel engine changes, it is possible to suppress fluctuations in the amount of generated steam.

In other words, in an exhaust heat recovery boiler system that is not equipped with the reheating burner 7, if the gas turbine load fluctuates, the generated steam load must also change, but the load of the reheating burner 7 (combustion amount ), load fluctuations of the gas turbine or diesel engine can be absorbed.

Furthermore, even if the load on the gas turbine or diesel engine l is constant, the generated steam load can be controlled by adjusting the load on the reheating burner 7.

FIG. 2 is a diagram showing the relationship between the generated steam load of the exhaust heat recovery boiler device and the gas turbine or diesel engine load when such an additional burner 7 is provided.

As shown in the figure, by changing the reheating burner load from minimum or stop to maximum, the generated steam load can be adjusted by about twice. (The area surrounded by points A, B, C, and D is the range of the generated steam load. Also, the line segment e is the generated steam load when the reheating burner is stopped.) In the above example, the first and second All of the steam produced by one evaporator is introduced into the heater to obtain high-temperature, high-pressure steam, but in the present invention, only the steam from one evaporator is introduced to the heater, and the steam from the other evaporator is For example, low-pressure steam can be taken out from the second evaporator, and medium-pressure steam can be taken out from the first evaporator.

Furthermore, in the present invention, it is also possible to stop the superheater and take out only medium pressure or low pressure steam.

As described above, according to the present invention, steam at both high and medium pressures can be taken out, and the response range of the normal air load is extremely wide.

[Effects] As described above, 1. The exhaust heat recovery boiler device of the present invention can reliably maintain the temperature of the gas introduced into the denitrification reactor at the optimum denitrification temperature, has extremely high denitrification efficiency, and has a long catalyst life. be converted into

In addition, NH, s H on the downstream side of the denitrification reactor
Precipitation of SO, etc. is suppressed, and the stability of the device during long-term operation is excellent.

Furthermore, it can widely respond to load fluctuations in gas turbines and diesel engines, changes in steam load, etc., making it extremely versatile.

[Brief explanation of drawings]

FIG. 1 is a system diagram of the exhaust heat recovery boiler device according to the embodiment, FIG. 2 is an operating characteristic diagram thereof, and FIG. 3 is an operating characteristic diagram of the denitrification reactor. 2... Superheater, 3... First evaporator,
4... Denitrification reactor, 5... Second evaporator. 6...Coal saver, 7...Additional burner.

Claims (2)

[Claims] (1) An exhaust heat recovery boiler device that introduces gas turbine or diesel engine combustion exhaust gas as a heat source, in which a superheater, a first evaporator, and a combustion chamber are installed sequentially from the gas distribution upstream side to the downstream side. It is equipped with a denitrification reactor having a contact layer for removing nitrogen oxides in exhaust gas by catalytic reduction decomposition, a second evaporator, and a carbon saver, and the feed water heated by the carbon saver is transferred to the first and second An exhaust heat recovery boiler device characterized in that the steam from at least one of the evaporators is guided to an evaporator and the steam from at least one of the evaporators is guided to a superheater. (2) The exhaust heat recovery boiler device according to claim 1, characterized in that a reheating burner is provided on the upstream side of the superheater.