JPS6249096B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a method for desulfurization in combustion furnaces.

Sulfur oxides (hereinafter referred to as SOx) generated when sulfur-containing fuel is burned are a substance that causes pollution, so there is a need for a method to effectively remove them. A technology has been proposed or put into practical use. However, all of these methods target liquid or gaseous fuels, so when applied to the desulfurization of exhaust gas that contains a large amount of dust, such as exhaust gas from a solid combustion furnace, the desulfurization equipment may be clogged with dust or desulfurization may occur. This led to problems such as a decline in the rate. As a solution to this problem, a dry in-furnace desulfurization method was proposed in which a solid Ca-containing SOx absorbent such as calcium carbonate (limestone), slaked lime, or dolomite is directly injected into the furnace. However, since this method directly supplies the absorbent into a high-temperature oxidizing atmosphere, the reaction rate of Ca is extremely low at around 15%, making it difficult to put it into practical use.

This invention was made in view of the above points, and an object of the present invention is to provide a method for desulfurizing a combustion furnace with an extremely high desulfurization rate.

The desulfurization method according to this invention performs combustion while supplying organic chloride into the furnace to generate HCl gas, and generates Ca-containing SOx at a furnace temperature of 900 to 1300°C.
It is characterized by supplying an absorbent.

Typical examples of organic chlorides include vinyl chloride resin, vinylidene chloride resin, and chlorobenzene. The organic chloride may be supplied into the furnace together with the fuel or combustion air, or may be supplied into the furnace from a location separate from the fuel supply or combustion air supply. As the fuel, solid fuel such as pulverized coal, which is obtained by pulverizing coal, is often used, but this is not limiting.

If the temperature inside the furnace is below 900℃, the SOx absorption reaction will take a long time or it will not be practical. When the temperature inside the furnace exceeds 1300℃, the reaction rate of Ca decreases. Therefore, the temperature inside the furnace is limited to 900 to 1300℃, and the particularly suitable temperature is
The temperature is 1000-1100℃. CaCO ₃ , Ca(OH) ₂ , dolomite, and the like are often used as Ca-containing SOx absorbents.

Next, the structure of the combustion furnace used in this invention will be explained.

In the horizontal cylindrical furnace shown in FIG. 1, reference numeral 1 denotes a furnace body consisting of a cylindrical peripheral wall 2, a front wall 3 and a rear wall 4 provided at both ends thereof, and is covered with a water jacket for absorbing heat. Reference numeral 5 denotes an opening formed in the center of the front wall 3, and has a combustion secondary air supply port 6 projecting forward. Reference numeral 7 denotes a burner arranged in the center of the combustion secondary air supply port 6 facing inward of the furnace, from which a mixture of pulverized coal and fuel transporting primary air is supplied. Reference numeral 8 denotes a wind box provided on the front surface of the front wall 3, which communicates with the inside of the furnace via the secondary air supply port 6 for combustion. Reference numeral 9 denotes an absorbent supply pipe arranged from the center of the length of the peripheral wall 2 to the axial center of the furnace, and has a forward-facing nozzle 10 at its tip. Reference numeral 11 denotes a peripheral wall 2 in front of the absorbent supply pipe 9.
The organic chloride supply pipe is located at the center of the furnace shaft.
It also has a forward facing nozzle 12 at its tip. The organic chloride can be supplied via this nozzle 12 or via the secondary air supply 6 or the burner 7. 13 is a flue provided at the rear end of the peripheral wall 2.

FIG. 2 shows a modification of the combustion furnace. This furnace 21 is a box-shaped large vertical furnace, which is also covered with a water jacket, and has a secondary air supply port for combustion at the lower end of the front wall 22, which has the same structure as that of the combustion furnace shown in FIG. 23, a burner 24, and a wind box 25 are provided, and a mixture of pulverized coal and primary air for fuel transportation is supplied from the burner 24. Further, an absorbent supply pipe 26 is arranged above the wind box 25, and an organic chloride supply pipe 27 is arranged below the same pipe 26. In this furnace as well, the organic chloride may be supplied from this supply pipe 27 or from the secondary air supply port 23 or the burner 24.

Experiment 1 A horizontal cylindrical furnace (inner diameter 1.5 m, length 7
In m), a mixture of pulverized coal, primary air, and vinyl chloride resin powder was supplied into the furnace from the burner 7, and secondary air was further supplied into the furnace from the wind box 8. The oxygen concentration of exhaust gas is 4.5% and the HCl gas concentration is 300ppm
The SO ₂ concentration before desulfurization was 900 ppm.

The temperature inside the furnace was adjusted to a predetermined value in the range of 800 to 1400°C, and CaCO ₃ was supplied as a SOx absorbent into the furnace at a ratio of Ca/S (equivalent ratio) = 3.0 (reaction time 1.7 to 1400°C).
2 seconds), Ca reaction rate at each furnace temperature (CaSO ₄ /
CaCO ₃ ) was measured. The above operation was also repeated without supplying the vinyl chloride resin powder. The results of these experiments are shown in FIG. As is clear from the figure,
The SOx absorbent has a furnace temperature of 900 to 1300℃, especially 1000 to 1000℃.
It showed high reactivity at 1100℃.

Experiment 2 Next, the temperature inside the furnace was adjusted to 1000℃, and the SOx absorbent was adjusted to a predetermined value in the range of Ca/S (equivalence ratio) = 1 to 4 and supplied (reaction time = 2 seconds). The conditions were the same as in Experiment 1, and the Ca reaction rate at each Ca/S value was measured. The above operation was also repeated without supplying the vinyl chloride resin powder. The results of these experiments are shown in FIG. As is clear from the figure, when vinyl chloride resin powder was supplied, a high Ca reaction rate was shown regardless of the Ca/S value.

As described above, according to the desulfurization method of the present invention, combustion is carried out while supplying organic chloride into the furnace.
Since HCl gas is generated, HCl gas exists at a low concentration in the combustion gas in the furnace, so the problem of corrosion of the furnace due to HCl gas is unlikely to occur, and it is difficult to handle, such as when using HCl gas or hydrochloric acid directly. There is no danger at all. Further, wastes such as synthetic resins can also be used as organic chlorides, and wastes can be used effectively. Furthermore, the desulfurization rate is at a temperature of 900~
The temperature is extremely high at 1300°C, and the reaction time is sufficient on the order of seconds.

[Brief explanation of the drawing]

Figures 1 and 2 are vertical sectional views showing the combustion furnace, Figure 3 is a graph showing the relationship between furnace temperature and Ca reaction rate, and Figure 4 is a graph showing the relationship between Ca/S equivalent ratio and Ca reaction rate. This is a graph showing. 6, 23... Secondary air supply port, 7, 24... Burner, 9, 26... Absorbent supply pipe, 11, 27...
...Organic chloride supply pipe.

Claims (1)

[Claims] 1 While feeding organic chloride into the furnace, combustion is performed to generate HCl gas, and the temperature inside the furnace is 900 to 1300.
A combustion furnace desulfurization method characterized by supplying a Ca-containing SOx absorbent in the range of °C.