JPS58124115A - Processing method of waste gas of coal boiler - Google Patents

Abstract

PURPOSE:To enable an easy deamination of NH4 salt from fly ash without using a particular deaminating device only by throwing the fly ash including NH4 salt into a circulative gas. CONSTITUTION:The fly ash generated from the boiler 1, passing thoug a denitrating device 2 and an air preheater 3, is gathered by a low temperature electric ash collecting device 4 as in the NH4 salt attached state. The fly ash attached with the NH4 salt and gathered by the device 4 is then thrown into the circulative gas to the boiler 1 and finally collected by the ash collector 9 which is provided for protecting a circulation blower 10. In this while, the fly ash is heated by a large amount of circulative gas and deaminated. Thus the deamination of NH4 salt from the fly ash can be easily performed without using any particular device.

Description

[Detailed Description of the Invention] As a fishing method for reducing the amount of nitrogen oxides (hereinafter referred to as NOMe) emitted from coal-fired boilers.

After suppressing the amount of MO□ generated from the boiler as much as possible by using a low yof combustion method using two-stage combustion or an exhaust gas recirculation method, the boiler exhaust gas is introduced into the denitrification equipment and N
It suppresses the Ox emission award.

Dry ammonia catalytic cracking systems are currently the mainstream denitrification equipment. However, when the above denitrification equipment is used, ammonium sulfate salt (hereinafter referred to as !'JH,4L) is produced by sulfur oxides in the ammonium exhaust gas leaking from the denitrification equipment, and the gas containing NH4'4 is cooled. and NH4 salt is precipitated. Moreover, if fine fly ash is present in the gas, NI? '.

Salt preferentially precipitates on the surface of the fly ash.

Therefore, if Seon EP4 is installed in the flow after the denitrification equipment, the fly ash supplemented with Seon EPt' will have NH4
There is a layer of salt.

The present invention relates to a process for decomposing and desorbing NH4m from fly ash (hereinafter referred to as deanxification), and aims to provide a deanxification process that is extremely simple and has low running costs. It is something to do.

There is currently no established devaluation process, but the one in Figure 1 is generally known from the promotion of rice. The fly ash generated from coal-fired boiler 1 is transferred to decopper removal equipment 2.
and passing through the air preheating section 5 (!: K L Tsute@
[I K M M with a layer of Ha salt at low temperature EP4
To be easted. The fly ash layered with NH4 sparrow collected by the hot ICP 4 is heated and decompressed by the Jujo device 5 and recovered by the Izumi-Shin 6.

be brought back to the front. In addition, the extraction gas from the boiler 1 can also be used as a heat source for detangling, and the hot air generating furnace 7 can be heated using auxiliary fuel.
It may also be hot air generated from. Of course, both may be used together.

In the process shown in FIG. 1, only the denitrification device 2 is considered as the NOX suppression method, and the case where the denitrification device 11i2 and a low NOX combustion method including an exhaust gas circulation method are used together is not considered. Since a seian equipment 5 is required in the process, the process becomes complicated and requires a heat source for desalination, so the running cost required for desalination becomes considerable. Furthermore, since sulfur oxides are generated during the decomposition of NH4M, the sulfur oxides are condensed, causing unfavorable circumstances.

The present invention has been developed to overcome the above-mentioned drawbacks.

This will be explained below with reference to FIG. FIG. 2 shows a deoxidization process when a denitrification device 112 and a low NOX combustion system including an exhaust gas circulation system are used together as a NOX suppression method.

The fly ash generated from the boiler 1 passes through the denitrification device 2 and the air preheating tank 3 and is collected at a low mff1P4 with NH4 salts attached to the surface.

The fly ash with adhering NH4m collected by the low d WF2 is put into the circulating gas to the boiler 1, and a large amount of fly ash is collected by the dust collector 9 installed to protect the circulating blower 10. The temperature is raised by the circulating gas, and the temperature is removed.
Recovered by II machine 9.

Dampers 11 and 12 are provided for controlling the circulating gas temperature. That is, if the main circulating gas at the outlet of the boiler 1 is too high, the fly bush will be de-assembled.
becomes lower. In such a case, hot gas (
For example, an economizer (artificial gas) is extracted and added to the main circulating gas, while the main circulating gas cap is reduced to serve as a gas volume control da/bar to keep the circulating gas temperature constant.

In Fig. 2, the place where fly ash is introduced is shown after the main circulation gas and the bleed gas from boiler 1 are mixed, but in order to reduce the bleed gas from boiler 1, the damper 12 is placed in a straight chain. Another possible method is to invest in

Since the clean circulating gas that has passed through the dust collector 9 is returned to the boiler 1, the sulfur oxides generated during the desulfurization process are decomposed, and the phenomenon of concentration of sulfur oxides does not occur.

Figure 3 shows an example of countermeasures in the case where the efficiency of the four-knitting machine 9 is low and extremely fine fly ash circulates without being collected by the collector 9, increasing the fly ash concentration during this process. . That is, this is a method in which the extremely fine fly ash collected in the low-temperature IP4 is removed by the molecular Itk machine 13 before being introduced into the circulating gas.

With the above configuration, by introducing the fly ash with NH4 salt attached into the circulating gas, the heat of the gas debases the fly ash, so there is no need for a special debasement device. The NH4 salt can be removed from the ash.

According to the present invention, the de-anxification device is not required and the de-anxification process is extremely simple. Furthermore, since a heat source for desulfurization is not required, the running for desulfurization and the desulfurization exhaust gas are returned to the boiler, so the sulfur oxides produced by the decomposition of NH4 salts are decomposed, and no concentration of sulfur oxides occurs. .

[Brief explanation of the drawing]

Figure 1 shows a conventional method for treating coal-fired boiler exhaust gas. FIG. 2 shows a method for treating coal-fired exhaust gas according to the present invention. FIG. 3 is a diagram showing another embodiment of the present invention. In the figure: 1 Coal-fired boiler 2 Denitrification device 3 Air preheater 4 Low-temperature electrostatic precipitator 5 De-balance device 6 Dust collector 7 Hot air generator
8 Recovered fly ash 9 Fruit dust machine 1G
Circulating blower - 11 dampers 12 dampers 13 classifiers and above Applicant: Sumitomo Heavy Industries Co., Ltd. Agent: Patent Attorney Kazuo Koyama, Sub-agent: Isamu Ohashi, Patent Attorney 1st WJ 1 Fig. 3 Fig. 2

Claims (1)

[Claims] A method in which coal-fired boiler exhaust gas is introduced into an ammonia catalytic reduction type denitrification device to denitrify it, introduced into a low-temperature dust collector to collect commercial dust, and a part of the boiler outlet gas is recycled to the boiler, The ammonium salt-adhered fly ash collected by the low-temperature dust collector is introduced into the re-ON storage exhaust gas to decompose and remove ammonium salts, and the fly ash is further removed by the dust collector installed in the 8-ring exhaust gas line A. A method for treating coal-fired boiler exhaust gas that requires very little waste gas.