JPS6346326B2 - - Google Patents

Description

[Detailed description of the invention]

This invention transports collected ash (hereinafter referred to as EP ash), which is a substance containing ammonium sulfate collected by a dust collector installed in the exhaust gas flow path of a combustion device such as a boiler of a power plant, to an incinerator for incineration. It is related to the device. With the recent increase in the size of power plants, sulfur oxides
By blowing ammonia NH ₃ to remove SOx and nitrogen oxides NOx, the amount of collected ash increases, and ammonium sulfate [(NH ₄ ) ₂ SO _{4 ]} increases by combining NH ₃ and sulfur dioxide gas. ], various difficult problems have arisen in terms of operation. First, several examples of the composition of EP ash from thermal power plants are quoted from literature and are shown in Table 1 below.

[Table] (Note) Although the main source is unburned carbon, there are also sources from the decomposition of carbon salts and oxides.

[Table] Carbon, which is an unburnt component in this content, must be completely incinerated to recover thermal energy, and vanadium contained in the ash is harmful and needs to be recovered because it is used as a raw material for alloys. As can be seen from Table 1, the amount of ammonium sulfate in EP ash is generally quite large. First, considering the properties of ammonium sulfate, the decomposition of ammonium sulfate shows two peaks indicating an endothermic decomposition reaction, as can be seen from the experimental results of differential thermal analysis, and the series of reactions changes in two stages as shown below. be. 1st stage: 270~380℃ (NH ₄ ) ₂ SO ₄ →2NH ₃ +SO ₃ +H ₂ O (NH ₄ ) ₂ SO ₄ →NH ₄ HSO ₄ +H ₂ O (acidic ammonium sulfate) 2nd stage: 380~490℃ NH ₄ HSO ₄ →NH ₃ +SO ₃ +H ₂ O 2NH ₄ HSO ₄ → (NH ₄ ) ₂ S ₂ O ₇ +H ₂ O (NH ₄ ) ₂ SO ₄ →2NH ₃ +2SO ₃ +H ₂ O Here in the second step The generated (NH ₄ ) ₂ S ₂ O ₇ immediately decomposes into NH ₃ , SO ₃ and H ₂ O. In this way, ammonium sulfate is completely decomposed and gasified into NH ₃ , SO ₃ , and H ₂ O at 500°C, so in order to completely decompose the ammonium sulfate salts in heavy oil ash, it is necessary to heat the heavy oil ash above 500°C. Recognize. The acidic ammonium sulfate (NH ₄ HSO ₄ ) produced in the above reaction has the property of melting at 146.9°C. If this molten material adheres to the fluid medium or the passage walls, various problems will occur. Therefore, in order to transport ammonium sulfate, it is necessary to first feed it rapidly into a furnace at a temperature of 490°C or higher, without carrying out the process under temperature conditions that would produce acidic ammonium sulfate. Experimental results also show that NOx due to NH ₃ injection,
Experiments have confirmed that the dew point of exhaust gas after SOx removal measures changes depending on its NH ₃ and reaches a maximum of 110°C. Based on these actual measurements and experiments, the present invention proposes a stable device free from blockage that should be adopted when transporting and supplying EP ash when incinerating EP ash in the swirling spouted bed furnace proposed earlier by the inventors. With the goal. In short, this invention allows EP ash to be heated to approximately 110°C to 270°C.
It is preferably maintained at approximately 130° C. to 250° C. and fed to the incinerator, and is further characterized by a feeding device using air flow transportation. Further, the device is characterized in that an air seal is used at the discharge port, and the amount of air for the air seal is increased when the EP ash supply is stopped to prevent clogging of the EP ash flow path. An apparatus according to the present invention will be explained below with reference to the drawings. Taking as an example the swirling spouted bed furnace that the inventors previously proposed as an incinerator, a fluidized medium 2 is accommodated in the swirling spouted bed furnace 1, which is a combustion furnace, and the swirling flow and rising jet of the medium are transmitted through a pipe 3a. , 3b. When the fluidized medium is heated by the starting burner 4 and reaches a temperature of approximately 500°C or more, preferably approximately 650°C, the EP ash is transferred from the storage tanks 5, 5' via the nozzles 6, 6' into the bed of the flowing medium. supplied and incinerated. In this case, when it is necessary to treat sludge and the like, fuel is supplied from the auxiliary combustion burner 7 to maintain the inside of the bed at the required temperature. When incinerating such EP ash, this invention has a maximum dew point of 110°C, a melting point of acidic ammonium sulfate (NH ₄ HSO ₄ ) of 146.9°C, and a decomposition value of ammonium sulfate to acidic ammonium sulfate of 270 to 380°C. Since it is ℃,
Air is the gas for transporting EP ash, and the temperature of the EP ash immediately rises during pneumatic transport, so the temperature in the transport passage for the air and EP ash should be set at approximately 110°C or higher and approximately 270°C or lower, preferably approximately 130°C or higher. Almost 250℃
We propose the following. Also, dehumidifying the air used for transporting EP ash facilitates control requirements such as dew point consideration and the need to reduce the amount of fluctuation in the temperature of the transport air. However, in this case, it is necessary to maintain the temperature in the range of about 110°C to 270°C in order to decompose the ammonium sulfate. We propose the device shown in Figure 1 as a device to raise the temperature of the air for transporting EP ash. Of the air passage 9 from the blower 8 for air transport to the nozzle 6 for discharging EP ash to the incinerator, the part from the EP ash discharge port 10 of the storage tank 5 to the nozzle 6 becomes an EP ash transport passage 9a. EP ash is discharged from the other EP ash storage tank 5' mainly by using the chute 11 which is an EP ash transport passage, but as in the case of the storage tank 5, pneumatic transport means can be used at the same time. When the EP ash transport passage 9a is used, the air supplied from the blower 8 is passed through the conduit 12, if necessary, through the dehumidifier 13, and heated to about 130° C. by the air preheater 14. Alternatively, air may be sent directly from the blower 8 to the air preheater 14 by switching the valves 15a and 15b. EP ash is supplied from the storage tank 5 via the rotary valve 16 and through the EP ash outlet 10 having a bench lily structure or the like.
It flows through the EP ash transport passage (ammonium sulfate-containing material transport passage) 9a. In this case, air and EP are heated by a heater 17a, which is an EP ash passage heating device using steam, electric heat, etc.
Both ashes are heated to approximately 160°C and discharged from the nozzle 6 into the swirling fluidized bed, and the EP ash is incinerated within the bed. Steam supplied to the heater 17a shown in the figure is supplied to the pipe 1
8 via valve 19a. to nozzle 6'
Steam to heater 17b, which is an EP ash passage heating device, is supplied via valve 19b. The means for heating may be not only steam, but also other means such as an electric heater. EP ash from storage tank 5' is transferred to rotary valve 16'.
It is supplied into the layer from a nozzle 6' via a conduit 11'. The storage tank 5' can be used for finely powdered EP ash, and the storage tank 5 can be used separately for humidified granular EP ash. The structure of the nozzles 6, 6' is an air seal structure as shown in FIG. Nozzle 6
It is enlarged to show its cross section. The nozzles 6, 6' may be provided with shielding plates 19, 19' to prevent decomposition of ammonium sulfate due to radiant heat from the fluidized medium 2. In addition, seal air boxes 20 and 20' are provided to prevent the nozzles 6 and 6' from rising in temperature, and to prevent hot gas from flowing in when the EP ash supply is stopped, and to prevent the nozzles from clogging. A plurality of seal air nozzles 21 having oblique jetting directions are provided. Seal air is in passage 9
It is carried out via a pipe line 22 and a valve 23 that branch out from there. When the air valve 24 provided in the pipe line 9 is open, the valve 2
3 is slightly opened to send a small amount of seal air to the seal air nozzle 21, and when the air valve 24 is fully closed and EP ash is not being supplied to the nozzle 6, the opening of the valve 23 is increased to effectively seal the air in the nozzle 6. Assume that there is. This control command is issued from the control box 25.
The activation/stopping of the rotary valve 16' for supplying EP ash to the EP ash chute 11 corresponds to the air valve 24, and this activation/stopping causes the valve 23' to open or slightly open. By carrying out this invention, there is no clogging of the EP ash transport passage and its discharge port nozzle, and controlling the transport air temperature range to a specified value increases the effect of preventing clogging. Air sealing effect of the nozzle Together with this, it provides various effects such as enabling continuous operation of the incinerator.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing piping and a cross-section of a device according to the present invention, and FIG. 2 is a cross-sectional view showing the structure of a nozzle air seal device. 1... Swirling spouted bed furnace (incinerator), 2... Fluidized medium,
5,5'...EP ash storage tank, 6,6'...nozzle, 8...
Blower, 9...Air passage, 9a...EP ash transport passage,
11... Chute, 13... Dehumidifier, 14... Air preheater, 15a, 15b... Valve, 16, 16'... Rotary valve, 17a, 17b... Heater (EP ash passage heating device), 18... Pipeline, 20, 20'...Seal air box, 21...Seal air nozzle, 2
3, 23'...Valve, 24...Air valve, 25...Control box.

Claims (1)

[Claims] 1. A device that supplies ammonium sulfate-containing collected ash to the ammonium sulfate-containing collected ash transport passage, and a device that supplies ammonium sulfate-containing collected ash transport passage
It consists of a heating device that heats to 110℃ to 270℃ and an air supply device installed at the outlet that sends out the ammonium sulfate-containing collected ash, and the amount of air at approximately 110 to 270℃ is supplied to the ammonium sulfate-containing collected ash outlet. When ammonium sulfate-containing collected ash is being supplied to the fluidized bed furnace, the air is small, and when the supply is stopped, a device is installed to increase the air supply. and a sealed air box surrounding a plurality of sealed air nozzles.