JPS58124107A - Operation of denitrating device for combined plant - Google Patents

Abstract

PURPOSE:To enable an operation of the plant at a low NOX concentration without degrading the heat efficiency of the plant by a method wherein when the temperature of exhaust gas is relatively low, the generation of NOX is suppressed by an injection of water or steam, whereas when the temperature is relatively high, by ammonia reduction. CONSTITUTION:At the timepoint when the exhaust gas temperature exceeds the lower temperature limit of a denitrating device of ammonia reduction due to an increase in load after a denitration by the water or steam injection at the starting of the plant, the denitration by the denitrating device is also used (see curve C6 in the graph), and when the effect appears, the denitration by the water or steam injection is stopped. Thereafter, the denitration is performed only by the denitrating device. As the denitration by the water or steam injection is not carried out on the gas turbine side during a normal operation of the plant, a heat loss can be decreased, thereby improving the total efficiency of the plant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a denitrification equipment for a combined gas turbine plant, and includes nitrogen oxides (NO,
') Relates to a method of operating a denitrification device to reduce the degree of li.

In FIG. 6 showing a system diagram of a typical conventional combined gas turbine plant (hereinafter referred to as a combined plant) in FIG. 1, a gas turbine 6 is rotated by the energy of exhaust gas combusted in a combustion chamber 3. Combustion chamber 3
A fuel supply line 4 and a water or steam injection line 5 are connected to the combustion chamber 1, and combustion air is supplied from the air duct 1 through the compressor 2 into the combustion chamber 3. Gas turbine 6 and compressor 2
are coaxially and directly connected, and a portion of the energy obtained by the gas turbine 6 is used by the compressor 2. Gas turbine exhaust gas passes through the exhaust gas duct 7 and is led to the waste heat boiler. The waste heat boiler consists of heat exchangers 9 and 12, a denitrification reactor 11 as an exhaust gas purification device is installed between these heat exchangers, and an ammonia injection line 10 is provided upstream of the denitrification reactor 11. In addition, in the figure, 8.14 is Danno (,13
, 15 is Yanou. In order to reduce the NOx concentration in the exhaust gas with such a device system, first the gas turbine combustion chamber 3
A method in which water injection (hereinafter referred to as W/I) or steam injection (hereinafter referred to as S/I) is performed from 2-in-5 to change the combustion state, and an ammonia injection line at the inlet of the denitrification reactor 11 NO from 10! Ammonia, which is a reducing gas, is injected, and the catalyst in the denitration reactor 11 reduces
A method of reducing the amount of work is also used.

NO in such a plant! The reduction method will be explained in more detail in FIG. In FIG. 2, when the plant is started up, the exhaust gas temperature T and the NO8 concentration increase almost linearly with respect to the time axis. When the concentration of NO and C rises to the vicinity of the plant's emission control device C1, there is W in the combustion chamber 3.
NO to doing /I or S/I! Reduce concentration. In this case, if W/I or S/I is not performed, the NoX concentration increases as shown by curve C2. At this initial stage, the temperature T of the exhaust gas at the inlet of the denitrification device 11 is 80.0% due to the ammonia and exhaust gas injected. Since this is the temperature range in which acidic ammonium sulfate is precipitated by the reaction with ammonia, the denitration equipment 11 cannot be operated by injecting ammonia.
The concentration increases and rises again to near the regulation value, but at this point the temperature is at which ammonia can be injected, so when ammonia is injected, it is lowered to below the limit value. In addition,
In this case, the NO□#1 degree of the denitrification equipment 11 population is 111c
It becomes like s.

The firefly plant operation is based on the KW inside the gas turbine combustion chamber 3.
/I or S/I and N by the denitrification device 11
O! Use reduction methods together. In the performance design of denitrification equipment that operates in this way, W/I or S/
Check the NO concentration while performing I in the denitrification equipment.
The amount of catalyst and ammonia injection in the denitrification equipment are planned under the conditions of O concentration.

However, the above-described denitrification method performs W/I or S/I in the gas turbine combustion chamber 3 not only at startup but also during normal operation, which has the disadvantage of reducing the thermal efficiency of the plant.

An object of the present invention is to provide a method for operating a denitrification device for a combined plant that can be operated at a low heat concentration below the emission regulation value without causing a decrease in the thermal efficiency of the plant.

The present invention provides for denitrification according to combustion conditions by injecting water or steam into the gas turbine combustion chamber without using the cough denitrification device when the exhaust gas temperature of the gas turbine device is lower than the operating lower limit temperature of the ammonia reduction denitrification device, On the other hand, when the temperature of the exhaust gas becomes equal to or higher than the lower limit temperature for operation of the denitrification device, the injection of water or steam is stopped, and denitration is performed by the ammonia reduction denitrification device.

In the present invention, when the load temporarily decreases during normal operation and the temperature of the denitrification equipment becomes below the above-mentioned lower limit temperature, the operation of the denitrification equipment is stopped in the same way as when starting up, and the W/I or S/I
It is possible to reduce the amount of waste by starting the process and adjusting the combustion conditions.

Hereinafter, the present invention will be explained in more detail with reference to the drawings. Third
The figure is a diagram showing an embodiment of the method of operating a combined plant according to the present invention. The difference from the conventional operating method shown in Figure 2 is that after denitration is performed by KW/I or S/I at startup, the exhaust gas temperature drops below the lower limit temperature of the denitrification device by ammonia reduction as the load increases. When the temperature rises, denitrification using the denitrification device 11 should be performed in combination with curve C6), and when the effect of step 7 appears, denitrification using W/I or S/IK should be stopped, and from then on, denitrification should be performed only with the denitrification device 11. In Figure 6, curve C8 shows the concentration of lice in the denitrification equipment 11 population. It is planned to have a high concentration at the entrance, and a high-level NO! The catalyst and ammonia injection rates are designed to be suitable for removal.

According to the above embodiment, W on the gas turbine side during normal operation
Since denitrification is not performed by /I or S/I, heat loss is reduced and the overall efficiency of the plant can be increased (in this case, the amount of catalyst and ammonia injection in the denitrification equipment increases). However, since gas turbine exhaust gas generally contains less dust and sulfur oxides, the life of the denitrification catalyst is long, and therefore the increased running cost of the denitrification equipment is not much of a problem compared to the heat loss.

As described above, according to the present invention, there is no need to perform W/I or S/I on the gas turbine side, so heat loss is small (as a result, highly efficient combined plant operation is possible. Since the W/I or S/I equipment on the side is used only in the low load zone, the equipment can be reduced.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a standard combined plant, and Figure 2 is a diagram of a conventional combined plant.
FIG. 3 is a diagram illustrating an operating method for reducing the number of chickens in a plant according to the present invention. 3... Combustion chamber, 4... Fuel supply twin, 5... Water or steam injection line, 6... Gas turbine, 7...
・・Exhaust gas duct, 9.12・・Heat exchanger, 10・・
- Ammonia injection line, 11... denitrification reactor. Agent Patent Attorney Takenaga Kawakita Figure 1 Figure 3

Claims (1)

[Claims] (1) When the exhaust gas temperature of the gas turbine equipment is lower than the minimum operating temperature of the ammonia reduction and denitrification equipment, water or steam is injected into the gas turbine combustion chamber without using the denitrification equipment, and denitrification is performed according to the combustion conditions. A method for operating a denitrification device for a combined plant, characterized in that when the exhaust gas temperature becomes equal to or higher than the lower operating limit temperature of the denitrification device, the injection of water or steam is stopped and denitration is performed by the ammonia reduction denitrification device.