JPH04358518A - Desulfurizing agent blowing device - Google Patents

Abstract

PURPOSE:To prevent clogging generated by the condensation of a desulfurizing agent blowing nozzle and keep high desulfurization reaction continuously and stably for a long time by installing a nozzle component with the given stretching angle enlarged into the tapered or trumpet shape at the end of a desulfurizing agent introduction tube. CONSTITUTION:A nozzle component 16 widened toward the end and stretched gradually on its nozzle section is installed at the end of a desulfurizing agent introduction tube. The nozzle shape is formed to satisfy the formula of D1/D2 >=0.5 and theta<=7 deg. when the aperture of the nozzle section 11 is set as D1, the aperture of its end as D2 and the stretching angle of the nozzle as theta. As a result, water content condensed on the outer peripheral face of the nozzle is not entrapped into the inner face of the nozzle, which can prevent the clogging generated by the condensation of nozzle and continuous stabilized high reaction can be retained for a long time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for purifying exhaust gas discharged from a boiler or the like, and more particularly to a desulfurizing agent injection apparatus suitable for preventing clogging of the desulfurizing agent due to dew condensation in the desulfurizing agent injection nozzle.

0002

[Prior Art] Sulfur compounds (SO
Acidic hazardous substances such as
It is contained at a ratio of 0.00 ppm and is a causative agent of acid rain and photochemical smog, so an effective means of removing it is strongly desired. Conventionally, wet methods (e.g. limestone-gypsum method) or dry methods (activated carbon method) have been used, but while the wet method has a high removal rate of harmful substances, it is difficult to treat wastewater and requires reheating of exhaust gas. However, the dry method has the problem of not being able to obtain a high removal rate. Therefore, it has been desired to develop a desulfurization method that does not require wastewater treatment, has low operating costs, and can provide a high removal rate.

[0003] In addition to the above-mentioned methods, desulfurization methods for exhaust gas from boilers and the like include a semi-dry method in which slaked lime or its slurry is sprayed into the exhaust gas, and a method in which limestone is directly dispersed in the high-temperature gas in the furnace or flue. Dry methods for removing acidic harmful substances have been proposed, and although these methods have the advantage of low equipment and operating costs, they all have the problem of low desulfurization rates.

FIG. 5 shows a typical flow sheet of a conventional method in which slaked lime or quicklime is sprayed into exhaust gas to react with SOx in the exhaust gas, and then removed by a dust collector. In the figure, exhaust gas 2 from a boiler 1 undergoes heat exchange with an air heater 3 to lower its temperature, and is introduced into a desulfurization tower 4. A desulfurizing agent 5 such as slaked lime is sprayed into the flue 6 or the desulfurizing tower 4, and water is also supplied at this time to lower the temperature of the exhaust gas 2 and increase the humidity. At this time, water may be supplied separately from the desulfurizing agent 5, or the desulfurizing agent 5 may be supplied as a slurry 7 at the same time. The reacted desulfurizing agent 5 is collected together with the ash in the exhaust gas 2 by a dust collector 8,
At the same time as being disposed of, it is released into the atmosphere from the chimney 9 as clean gas.

[0005] When performing exhaust gas treatment using such a method,
The desulfurizing agent 5 sticks to the inner surface of the desulfurizing agent injection nozzle 11 that supplies the desulfurizing agent 5, causing clogging and impairing the smooth introduction of the desulfurizing agent 5.

That is, as shown in FIG. 6, slaked lime and water for flue gas desulfurization are blown from both nozzles installed in the flue 6. During operation, the tip of the desulfurizing agent injection nozzle 11 on the downstream side becomes wet, making it easy for slaked lime and dust to adhere and harden, which clogs the nozzle hole and prevents smooth injection of slaked lime. There was a problem of interference.

[0007]

[Problems to be Solved by the Invention] As mentioned above, in conventional flue gas desulfurization equipment, water is introduced at the upstream side of the nozzle section of the introduction pipe that introduces the desulfurization agent, so that the exhaust gas in the flue is , from about 150°C to around 100°C, and at the same time, the desulfurizing agent injection nozzle section is also cooled. Also,
The desulfurizing agent injection nozzle part is also cooled by the carrier gas, and in particular, if it is cooled to below the saturation temperature (approximately 54°C), water vapor will condense and adhere to the outer circumferential surface of the nozzle, and the condensed moisture will be used to inject the desulfurizing agent. Penetrates to the inner surface of the nozzle.

When slaked lime powder is introduced as a desulfurizing agent under such conditions, the desulfurizing agent immediately adheres to the desulfurizing agent injection nozzle and hardens, and deposits gradually accumulate in layers. That is, FIGS. 7A to 7F schematically show the mechanism of the desulfurization agent adhesion phenomenon caused by dew condensation on the outer peripheral surface of the desulfurization agent injection nozzle. Desulfurizing agent injection nozzle 11
When water droplets 14 are generated on the outer circumferential surface of the desulfurizing agent blowing nozzle 11, the water droplets 14 are easily drawn into the inner surface of the desulfurizing agent injection nozzle 11 by the small entrained vortex 21, as shown in FIGS. 7(a) and 7(b). The desulfurizing agent 5 and combustion ash in the exhaust gas adhere to this, forming a slurry 15 [FIG. 7(c)] and drying and solidifying [FIG. 7(d)]. Once this is generated, vortices are likely to be generated, water droplets 14 are increasingly drawn in, and the attached and solidified desulfurization agent 13 grows [Fig. 7(e), (
f)]. For this reason, the hole of the desulfurizing agent injection nozzle 11 becomes narrow, preventing the smooth introduction of the desulfurizing agent 5, and in extreme cases, the nozzle may become clogged, which impedes the desulfurizing process of the exhaust gas. Therefore, it has been desired to design a desulfurizing agent injection nozzle 11 that does not cause such nozzle clogging problems.

An object of the present invention is to solve the above-mentioned problems in the prior art, and to reduce SOx in exhaust gas by introducing a desulfurizing agent into the flue of a combustion furnace such as a boiler or into a desulfurizing tower.
In the desulfurizing agent injection device of exhaust gas purification equipment, which removes acidic hazardous substances such as chlorine and HCl by reaction, the structure is simple and can easily prevent the desulfurizing agent from clogging due to dew condensation on the outer circumferential surface of the desulfurizing agent injection nozzle. The purpose of the present invention is to provide an inexpensive desulfurizing agent injection device.

0010

[Means for solving the problem] As mentioned above, in order to solve the problems of the conventional desulfurizing agent injection nozzle, it is necessary to heat the inner surface of the nozzle that supplies the desulfurizing agent to a temperature higher than that required to prevent condensation. It is necessary to either retain or mechanically remove the attached and hardened desulfurizing agent. However, in practice, method (1) requires a complicated heating means, and method (2) is difficult to mechanically remove during operation, so the present invention improves the shape of the desulfurizing agent injection nozzle, The problem of clogging caused by the desulfurizing agent is solved by providing a desulfurizing agent injection nozzle with a specific shape that prevents moisture condensed on the outer peripheral surface of the nozzle from being drawn into the inner surface of the nozzle.

In the desulfurizing agent blowing device of the present invention, a tapered nozzle (cylindrical) member with a gradually enlarged cross section is provided at the tip of the desulfurizing agent blowing nozzle, and a nozzle portion of the tapered nozzle member is provided. The nozzle is designed in a shape that simultaneously satisfies D1/D2≧0.5 and θ≦7 degrees, where D1 is the aperture of the tapered nozzle member, D2 is the aperture of the tip of the tapered nozzle member, and θ is the divergence angle (taper angle). By doing so, the object of the present invention can be achieved.

[0012] When the value of D2/D1 becomes larger than 2 and θ exceeds 7 degrees, the inclination of the end widening part of the tapered nozzle member becomes steep, and a small vortex is generated at the widening part of the tapered nozzle tip. This is undesirable because water droplets condensing on the outer circumferential surface of the nozzle are drawn into the inner surface of the nozzle, where the desulfurizing agent adheres and solidifies, causing the nozzle to become clogged.

[0013]

[Operation] The cause of blockage of the desulfurizing agent injection nozzle is that the flow velocity at the desulfurizing agent blowing part is high, so a vortex is generated at the tip of the nozzle, and the water on the outer periphery of the nozzle and the blown desulfurizing agent are caught up in this vortex. This is because the desulfurizing agent gradually adheres to the inner surface of the desulfurizing agent injection nozzle and grows. therefore,
If the cross-section of the nozzle is a tapered nozzle that gradually expands toward the end, and if the flow rate of the desulfurizing agent in the tapered nozzle is kept low enough to prevent turbulence, the generation of vortices at the tip of the tapered nozzle can be suppressed. Therefore, moisture condensed on the outer circumferential surface of the nozzle is drawn into the inner surface of the nozzle, and the problem of nozzle clogging caused by adhesion and solidification of the desulfurizing agent is solved.

[0014]

EXAMPLES Examples of the present invention will be described below in more detail with reference to the drawings.

FIG. 1 is a system diagram showing the configuration of an exhaust gas purification device using the desulfurizing agent injection device of the present invention. In the figure, the boiler 1 includes a coal-fired boiler, a heavy oil-fired boiler, and the like, and the combustion exhaust gas 2 flows downstream while containing sulfur compounds (SO2, etc.) and combustion ash. On the way, heat is exchanged with the air heater 3, and a water spray nozzle 12 and a desulfurization agent injection nozzle 11 are provided in the flue 6 downstream thereof, where a primary desulfurization reaction is performed. Furthermore, the exhaust gas 2 enters the desulfurization tower 4, where it is sprayed with water again to complete the desulfurization reaction, collected by the dust collector 8, and disposed of, and clean exhaust gas is released into the atmosphere from the chimney 9. be done.

In this embodiment, a case will be described in which slaked lime powder is used as a desulfurizing agent to desulfurize exhaust gas from a coal-fired boiler.

In FIG. 1, the temperature of exhaust gas 2 from a boiler 1 is lowered by an air heater 3, water is sprayed from a water spray nozzle 12 in a flue 6 downstream thereof, and is jetted from a desulfurizing agent injection nozzle 11. Water is added to the desulfurizing agent 5. moreover,
Water is also added to the desulfurization tower 4 by spraying water. The desulfurizing agent 5 subjected to such water addition treatment reacts with acidic harmful substances such as SO2 in the exhaust gas, and the reacted desulfurizing agent 5 is collected together with the ash in the exhaust gas 2 by a dust collector 8 and disposed of. . When the desulfurization agent 5 is injected, water is sprayed and supplied into the flue 6 or the desulfurization tower 4, but this is intended to improve the desulfurization reaction rate by lowering the temperature of the exhaust gas 2 and increasing the humidity. be.

At this time, the desulfurizing agent injection nozzle 11 is cooled by the water spray and is also cooled by the carrier gas that carries the desulfurizing agent 5 in airflow, so that moisture adheres to the outer peripheral surface of the nozzle in the form of dew. This penetrates into the inner surface of the nozzle. When slaked lime powder, which is the desulfurizing agent 5, is introduced, the desulfurizing agent immediately adheres to the inner surface of the nozzle and solidifies, and the desulfurizing agent is gradually piled up, which may cause the nozzle to become blocked. Therefore, as shown in FIGS. 2(a) to 2(c),
A tapered nozzle member (Venturi tube shape) 16 whose cross section at the tip of the nozzle is gradually enlarged is attached to the tip of the desulfurizing agent injection nozzle 11 . That is, at this time, the relationship between the aperture D1 of the nozzle portion of the tapered nozzle member 16 and the aperture D2 of the tip end of the tapered nozzle member 16 is set as D1/D2≧0.5, and the nozzle spread angle (taper angle) θ was set to 7° or less (the angle at the tip of the tapered nozzle member 16 is also the same). It is necessary to maintain a relationship in which a vortex in the opposite direction to the traveling direction of the exhaust gas 2 is not generated, as in the divergent part of the Venturi tube [FIG. 2(b)]. If this is D2/D1≫
2 (D1/D2≪0.5), θ≫7°, an entrainment vortex 21 is generated at the enlarged part of the tapered nozzle member 16 as shown in FIG. 2(c), and dew condensation occurs. water droplets 14
On the other hand, if the taper angle θ is small and the nozzle has an elongated shape, the effect of suppressing the vortices is reduced. From the above, the tapered nozzle member 16 in this embodiment
The nozzle shape was such that 1>D1/D2≧0.5 and 3°<θ<7° were satisfied at the same time. Therefore, the tip has a fairly acute angle, and the moisture (water droplets) on the outer circumferential surface of the nozzle is blown away, preventing moisture from entering the inner surface of the nozzle, and the inner surface of the nozzle is always kept dry. Therefore, the adhesion and solidification phenomenon of the desulfurizing agent 5 inside the nozzle and near the tip does not occur.

As described above, by providing the above-mentioned tapered nozzle member 16 at the tip of the desulfurizing agent introduction pipe, moisture (
This prevents the penetration of condensed water, etc., and prevents the desulfurization agent from adhering and solidifying. Therefore, the desulfurization reaction can be continued continuously, and the desulfurization reaction efficiency is further improved.

[0020] The tapered nozzle member that widens toward the end provided at the tip of the desulfurizing agent introduction pipe exemplified in the above embodiments is as follows:
Although the desulfurizing agent blowing nozzle has been shown as an example of a desulfurizing agent injection nozzle that has a tapered shape that expands at a predetermined expansion angle, it is also possible to use a trumpet-shaped nozzle member 1 that has a trumpet-shaped cross section as shown in FIG. 3, for example.
7, it is possible to prevent clogging of the desulfurizing agent as a desulfurizing agent injection nozzle. When spread out in a trumpet shape, the desulfurizing agent flows along this, which improves the dispersion effect of the desulfurizing agent and contributes to promoting the desulfurization reaction.

FIG. 4 shows a structure in which a wear-resistant material 18 is attached to the inner surface of a tapered or trumpet-shaped nozzle to prevent wear caused by the desulfurizing agent. As a result, a long life of the nozzle can be expected.

[0022]

Effects of the Invention The desulfurizing agent injection device of the present invention has the following excellent effects, so that a high desulfurization reaction can be stably maintained continuously over a long period of time in exhaust gas desulfurization equipment.

(1) By providing a tapered or trumpet-shaped enlarged nozzle member with a predetermined widening angle at the tip of the desulfurizing agent introduction pipe, the generation of vortices at the nozzle tip is suppressed, and the outer peripheral surface of the nozzle is Since no condensed water is drawn in, it is possible to prevent desulfurizing agent powder such as slaked lime from adhering to the inner surface of the nozzle and hardening.

(2) Condensed moisture is blown away at the acute-angled portion of the tip of the nozzle member, which is enlarged in a tapered or trumpet shape, so that moisture does not penetrate into the inner surface of the nozzle. Therefore, the desulfurizing agent powder can always be sprayed in a dry state.

(3) The desulfurizing agent injection nozzle of the present invention provided at the tip of the desulfurizing agent introduction pipe has a simple structure and can be easily designed and manufactured, resulting in low equipment costs.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the overall configuration of a boiler using an exhaust gas desulfurization apparatus having a desulfurization agent injection nozzle exemplified in an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of the configuration of a tapered nozzle member illustrated in an example of the present invention.

FIG. 3 is a schematic diagram showing an example of the configuration of a trumpet-shaped nozzle member illustrated in an example of the present invention.

FIG. 4 is a schematic diagram showing an example of the configuration of a nozzle member in which a wear-resistant material is attached to a tapered portion or a trumpet-shaped portion illustrated in an example of the present invention.

FIG. 5 is a schematic diagram showing the overall configuration of a boiler equipped with a conventional exhaust gas desulfurization device.

FIG. 6 is a schematic diagram showing the configuration of a conventional desulfurizing agent blowing nozzle and a water spray nozzle.

FIG. 7 is a schematic diagram showing the mechanism of adhesion and solidification of desulfurization agent powder at the tip of a conventional desulfurization agent injection nozzle.

[Explanation of symbols]

1...Boiler
2...Exhaust gas 3...Air heater
4...Desulfurization tower 5...Desulfurization agent
6... Flue 7... Slurry
8... Dust collector 9... Chimney
10...Desulfurizing agent introduction pipe 11...Desulfurizing agent injection nozzle 12...Water spray nozzle 13...Desulfurizing agent adhered and solidified 14...Water droplets 15...Slurry
16...Tapered nozzle member 17...Trumpet-shaped nozzle member 18...Wear-resistant material 19...Involved vortex

Claims (2)

[Claims] Claim 1: A desulfurization agent injection device for exhaust gas purification equipment that introduces a desulfurization agent into a flue of a combustion furnace or into a desulfurization tower to remove acidic harmful substances contained in exhaust gas, the desulfurization agent injection device In this method, a nozzle member with a gradually expanding nozzle cross section is provided at the tip of the desulfurizing agent introduction pipe, and the nozzle member has a diameter of D1, a diameter of the tip of the nozzle, D2, and a diameter of D2. When the spread angle is θ, D1
A desulfurizing agent injection device characterized by having a shape that simultaneously satisfies /D2≧0.5 and θ≦7 degrees. 2. The desulfurizing agent blowing device according to claim 1, wherein the nozzle member which is flared toward the end is made of a cylindrical member whose cross section is enlarged in a tapered shape or a cylindrical member whose cross section is enlarged in a trumpet shape. .