Sulfuric acid storage tank

Abstract

To avoid progress of corrosion in a tank caused by dispersion of sulfuric acid fed into the tank, on a liquid surface, in a sulfuric acid storage tank for storing concentrated sulfuric acid.SOLUTION: A sulfuric acid storage tank 100 includes: a tank body 1 for storing sulfuric acid; and a feeding pipe 2 for feeding sulfuric acid to the inside of the tank body 1. In the sulfuric acid storage tank 100, the feeding pipe 2 has a jetting port 24 for jetting sulfuric acid above a gas-liquid interface inside the tank body 1. In the jetting port 24, a jetting direction of sulfuric acid is directed to a direction toward a side plate 11 of the tank body 1. Between the side plate 11 inside the tank body 1 and the jetting port 24, an anticorrosive protective plate 3 is arranged.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sulfuric acid storage tank. [Background technology]

[0002] In various industrial facilities, steel tanks that exhibit corrosion resistance due to the formation of a protective precipitated film of iron sulfate on the steel surface are widely used as tanks for storing concentrated sulfuric acid (98% by mass sulfuric acid) (hereinafter referred to as "sulfuric acid tanks" in this specification) (Patent Document 1).

[0003] It has long been known that there is a risk that corrosion of the tank walls will progress quickly in "sulfuric acid storage tanks" when concentrated sulfuric acid absorbs moisture from the air and dilutes, especially near the liquid surface (waterline) in the tank. To reduce this risk, conventional "sulfuric acid storage tanks" have been designed with various methods to prevent localized dilute sulfation near the liquid surface of the sulfuric acid.

[0004] Patent Document 1 discloses a sulfuric acid storage tank in which a portion of the sulfuric acid is repeatedly discharged into the tank when it is extracted from the tank, and the water vapor in the air flowing into the tank is absorbed by the sulfuric acid being repeatedly discharged. Patent Document 2 discloses a sulfuric acid tank in which air is injected into the tank from near the bottom of the tank below the liquid level (waterline), thereby preventing localized dilution of the sulfuric acid.

[0005] However, in the "sulfuric acid storage tank", not only does sulfuric acid dilute near the liquid surface (waterline) in the tank as described above, but also droplets of concentrated sulfuric acid scattered irregularly in various directions on the liquid surface when sulfuric acid is fed into the tank, which dilutes the sulfuric acid and adheres to various parts of the tank, causing rapid local corrosion in various parts of the tank. The risk of corrosion progression caused in this way is difficult to sufficiently reduce by the above-mentioned conventional methods, and it is also difficult to identify places with a high risk of corrosion progressing, making it difficult to take effective measures. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 57-18646 [Patent Document 2] JP 2003-64491 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to prevent the progression of corrosion inside a sulfuric acid storage tank for storing concentrated sulfuric acid, which is caused by the sulfuric acid being splashed on the liquid surface as it is fed into the tank. [Means for solving the problem]

[0008] The inventors of the present invention came up with the idea that the above-mentioned problems can be solved by spraying the sulfuric acid in the sulfuric acid storage tank toward the side plate so that the sulfuric acid does not fall directly onto the liquid surface, and further by providing a corrosion-resistant protective plate between the side plate and the spray port to catch the sprayed sulfuric acid, and thus completed the present invention. Specifically, the present invention provides the following.

[0009] (1) A sulfuric acid storage tank comprising a tank body for storing sulfuric acid and an inlet pipe for feeding sulfuric acid into the tank body, the inlet pipe having an outlet for spraying sulfuric acid above a gas-liquid interface inside the tank body, the outlet being oriented so that the sulfuric acid is sprayed toward a side plate of the tank body, and a corrosion-resistant protective plate is disposed between the side plate and the outlet inside the tank body.

[0010] In the sulfuric acid storage tank (1), the sulfuric acid pumped into the tank does not splash irregularly on the liquid surface. In addition, the arrangement of a corrosion-resistant protective plate avoids the risk of corroding the side plate in the direction from which the sulfuric acid is sprayed. This effectively prevents the progression of corrosion inside the tank caused by sulfuric acid splashing on the liquid surface.

[0011] (2) The sulfuric acid storage tank described in (1), wherein the corrosion-resistant protective plate is suspended from the top plate of the tank body via a fixing part that detachably joins the top plate of the tank body and the corrosion-resistant protective plate.

[0012] According to the sulfuric acid storage tank of (2), the corrosion-resistant protective plate can be replaced in a short time by simple work. Therefore, by focusing on the progress of corrosion of the corrosion-resistant protective plate and repeatedly replacing the corrosion-resistant protective plate as necessary, the above-mentioned effects of the sulfuric acid storage tank described in (1) can be enjoyed over a long period of time at low cost.

[0013] (3) A sulfuric acid storage tank as described in (1) or (2), wherein the corrosion-resistant protective plate is suspended at a position within 0.3 m from the side plate, and the distance between the nozzle and the corrosion-resistant protective plate is within 0.3 m.

[0014] According to the sulfuric acid storage tank of (3), it is possible to more reliably prevent splashes of concentrated sulfuric acid pumped into the tank from adhering to any place other than the corrosion-resistant protective plate, thereby further improving the reliability of the above-mentioned effects provided by the sulfuric acid storage tank described in (1) or (2).

[0015] (4) A sulfuric acid storage tank as described in (1) or (2), in which the inlet pipe is joined to the top plate via an inlet pipe fixing part that detachably joins the top plate of the tank body and the inlet pipe.

[0016] According to the sulfuric acid storage tank of (4), when the corrosion of the inlet pipe progresses due to the concentrated sulfuric acid being fed into the tank remaining in the inlet pipe or due to a small amount of sulfuric acid splashed off the corrosion-resistant protective plate adhering to the inlet pipe in the sulfuric acid storage tank described in (1) or (2), the inlet pipe can be replaced in a short time by a simple operation. Therefore, by repeatedly replacing the inlet pipe as necessary, the above-mentioned effects of the sulfuric acid storage tank described in (1) or (2) can be enjoyed for a long period of time at low cost. Effect of the Invention

[0017] According to the present invention, in a sulfuric acid storage tank for storing concentrated sulfuric acid, the progression of corrosion inside the tank caused by the sulfuric acid being splashed on the liquid surface as it is fed into the tank can be prevented. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a perspective view showing a schematic configuration of a sulfuric acid storage tank according to the present invention. [Diagram 2] FIG. 2 is a side view (cross-sectional view) showing a schematic configuration of the sulfuric acid storage tank of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described. However, the present invention is not limited to the embodiment described below.

[0020] <Sulfuric acid storage tank> The "sulfuric acid storage tank" of the present invention is an industrial storage tank for storing concentrated sulfuric acid (98% by mass sulfuric acid) that is installed alongside various industrial facilities. FIG. 1 is a diagram showing a schematic overall configuration of a sulfuric acid storage tank 100, which is an example of an embodiment of the present invention. As shown in the figure, the sulfuric acid storage tank 100 is mainly characterized by having at least a tank body 1 for storing sulfuric acid, an inlet pipe 2 for feeding sulfuric acid into the inside of the tank body 1 from the direction of the top plate 12, and a corrosion-resistant protective plate 3 that is arranged inside the tank body 1 and toward which sulfuric acid is sprayed. Note that, as long as the "sulfuric acid storage tank" of the present invention has these characteristic configurations, it may further include various other configurations that can be arranged in an industrial sulfuric acid storage tank, such as a mechanism for taking out sulfuric acid, a mechanism for feeding and discharging liquids and gases other than sulfuric acid, and a mechanism for stirring the liquid in the tank, although the illustrations are omitted in each figure.

[0021] [Tank body] The tank body 1 is, for example, a sealed tank made of steel that exhibits corrosion resistance by forming a protective precipitated film of iron sulfate on the steel surface. It may be made of various other metals that have corrosion resistance, and may be coated with PTFE or the like. The tank body 1 is equipped with a top plate 12 that seals the upper part (top surface side), and the overall shape is not particularly limited as long as it has a structure that has a predetermined airtightness. The tank having a roughly rectangular prism shape as shown in FIG. 1 is merely one example.

[0022] [Feed pipe] The feed pipe 2 is a pipe for feeding concentrated sulfuric acid into the inside of the tank body 1, and is preferably made of a metal having the same corrosion resistance as the tank body 1.

[0023] 1 and 2, the feed pipe 2 is joined to the top plate 12, and is inserted into the tank body 1 through the top plate 12. The location of the feed pipe 2 on the top plate 12 is not particularly limited, but it is preferable that the feed pipe 2 is installed (inserted) in the vicinity of the side plate 11 rather than in the center, specifically, in a position where the distance from the nozzle 24 at the end of the feed pipe 2 to the inner surface of the side plate 11 is within 0.8 m.

[0024] The vertical position of the feed pipe 2 is such that the nozzle 24 at its end is located at a position where it can spray sulfuric acid above the gas-liquid interface inside the tank body 1. The feed pipe 2 is inserted from the top plate 12 (specifically, from a hole drilled in the top plate 12) and extends vertically downward inside the tank body 1, where it is bent at a bent portion 23 toward the side plate 11. Due to this bending, when sulfuric acid is supplied into the inside of the tank body 1, the spray direction of sulfuric acid from the nozzle 24 at the end of the feed pipe 2 is directed toward the side plate 11 of the tank body 1.

[0025] Regarding the direction of sulfuric acid ejection from the nozzle 24, the above-mentioned "direction toward the side plate" does not necessarily have to be the shortest path connecting the nozzle 24 and the side plate, nor does it have to be the horizontal direction or the normal direction of the side plate. Moreover, this direction does not have to be a straight path, and does not have to be always kept in the same direction. It is sufficient that the ejection direction of sulfuric acid from the nozzle 24 is appropriately changed from the vertical downward direction toward the side plate so that most of the ejected sulfuric acid, preferably all of it, can reach the opposing corrosion-resistant protective plate 3 without directly dropping onto the liquid surface. Specifically, depending on the distance between the nozzle 24 and the corrosion-resistant protective plate 3, the height of the nozzle 24 from the gas-liquid interface, and the ejection pressure of sulfuric acid, if the distance between the nozzle 24 and the corrosion-resistant protective plate 3 is about 0.15 m, as a guideline, the ejection direction of sulfuric acid from the nozzle 24, i.e., the bending angle of the bent portion, is preferably 30° to 60° when the vertical downward direction is 0° and the horizontal direction is 90°. By setting the sulfuric acid ejection direction to 30° or more in the above sense, it is possible to impart horizontal kinetic energy to the sulfuric acid and make most of the sulfuric acid reach directly to the surface of the corrosion-resistant protective plate 3. Also, by setting this direction to 60° or less, the sulfuric acid that has reached the corrosion-resistant protective plate 3 is less likely to scatter in the normal direction from the surface of the corrosion-resistant protective plate 3 and is more likely to flow downward quickly along the surface.

[0026] In the sulfuric acid storage tank 100 shown in Figures 1 and 2, the direction of sulfuric acid spray from the nozzle 24 is set to an optimal angle determined in advance by the bending angle of the bent portion 23 of the feed pipe 2. However, in the sulfuric acid storage tank of the present invention, the direction of sulfuric acid spray from the nozzle 24 can be set to "toward the side panel" by, for example, attaching an angle-variable nozzle to the nozzle 24 that can control the direction of sulfuric acid spray.

[0027] Although the inlet pipe 2 can be fixed to the tank body 1 by welding, it is preferable that the inlet pipe 2 is indirectly fixed to the top plate 12 of the tank body 1 in a detachable manner via an inlet pipe fixing part 22 or the like in order to facilitate replacement. Specifically, as an example, as shown in Fig. 2, the inlet pipe 2 has a fixing flange 21, and is preferably joined to an inlet pipe fixing part 22, which also has a flange and is stably installed on the upper surface of the top plate 12, by a detachable joining method such as by fixing the two to each other with bolts. By attaching a height adjuster that can control the insertion depth of the inlet pipe 2 into the tank body 1, the direction of sulfuric acid ejection from the ejection port 24 can be made to be "toward the side plate".

[0028] [Corrosion-resistant protective plate] The corrosion-resistant protective plate 3 is a plate-shaped member made of a corrosion-resistant material that is installed to receive the sulfuric acid sprayed from the nozzle 24 of the feed pipe 2 toward the side plate 11 and drop it downward. A steel plate having the same corrosion resistance as the tank body 1 can be used, or a structure in which an abrasion-resistant material is attached to the surface of a support material can be used.

[0029] 1 and 2, the corrosion-resistant protective plate 3 is joined to the top plate 12 and is suspended inside the tank body 1, penetrating the top plate 12. The position of the corrosion-resistant protective plate 3 on the top plate 12 may be any position between the side plate 11 inside the tank body 1 and the nozzle 24 of the feed pipe 2, and is not particularly limited thereto. However, it is preferable that the corrosion-resistant protective plate 3 is located in the vicinity of the side plate 11, specifically, within a distance of 0.3 m from the inner surface of the side plate 11. In terms of the relative positional relationship with the feed pipe 2, the distance between the corrosion-resistant protective plate 3 and the nozzle 24 of the feed pipe 2 is preferably within 0.3 m.

[0030] The width of the corrosion-resistant protective plate 3 may be long enough to prevent the sulfuric acid from reaching the side plate 11, taking into consideration the diffusion angle of the sulfuric acid ejected from the ejection port 24 of the feed pipe 2. The height of the corrosion-resistant protective plate 3 is preferably long enough to place a part of the lower end of the corrosion-resistant protective plate 3 below the gas-liquid interface, i.e., to be immersed in the sulfuric acid solution.

[0031] Moreover, it is more preferable that the shape of the lower end of the corrosion-resistant protective plate 3 is bent toward the center of the tank at a position higher than the position expected to be the height of the gas-liquid interface to form an inclined surface. In this case, the bending angle of the lower end of the corrosion-resistant protective plate 3 is preferably 10° to 30°, with the vertical downward direction being 0°. By arranging the corrosion-resistant protective plate 3 as described above, the inflow speed of the liquid (more specifically, the vertical component of the speed) when sulfuric acid flows into the gas-liquid interface along the surface of the corrosion-resistant protective plate 3 can be attenuated, and scattering at the gas-liquid interface can be more reliably prevented.

[0032] The corrosion-resistant protective plate 3 can be fixed to the tank body 1 by welding, but in order to facilitate replacement, it is preferable that the corrosion-resistant protective plate 3 is indirectly fixed to the top plate 12 of the tank body 1 in a detachable manner via a corrosion-resistant protective plate fixing part 32 or the like. Specifically, as an example, as shown in Fig. 2, it is preferable that the corrosion-resistant protective plate 3 has a fixing flange 31 and is joined to a corrosion-resistant protective plate fixing part 32, which also has a flange and is stably installed on the upper surface of the top plate 12, by a detachable joining method such as by fixing them to each other with bolts. [Explanation of symbols]

[0033] 1 Tank body 100 Sulfuric acid storage tank 11 Side Panel 12 Tabletop 2 Feed pipe 21 Fixed flange 22 Feed pipe fixing part 23 Bend 24 spout 3. Corrosion-resistant protective plate 31 Fixed flange 32 Corrosion-resistant protective plate fixing part

Claims

1. A tank body for storing sulfuric acid, A feed pipe for feeding sulfuric acid into the interior of the tank body, Comprising, A sulfuric acid storage tank, The feed pipe has a spout for ejecting sulfuric acid above the gas-liquid interface inside the tank body, The spout is directed in a direction in which the ejection direction of the sulfuric acid is toward the side plate of the tank body, and an angle-variable nozzle having a movable range for making the ejection direction of the sulfuric acid face the side plate can be attached to the spout, A corrosion-resistant protection plate is disposed at a position between the side plate and the spout inside the tank body, At the lower end of the corrosion-resistant protection plate, below the spout and above the gas-liquid interface, a splash-preventing inclined surface of sulfuric acid at the gas-liquid interface that bends at a bending angle of 10° or more and 30° or less with 0° being vertically downward is formed in the central direction of the interior of the tank body, Sulfuric acid storage tank.

2. The corrosion-resistant protection plate is suspended from the top plate via a fixing portion that detachably joins the top plate of the tank body and the corrosion-resistant protection plate, The sulfuric acid storage tank according to Claim 1.

3. The corrosion-resistant protection plate is suspended at a position where the distance from the side plate is within 0.3 m, The distance between the spout and the corrosion-resistant protection plate is within 0.3 m, The sulfuric acid storage tank according to Claim 1 or 2.

4. The feed pipe is joined to the top plate via a feed pipe fixing portion that detachably joins the top plate of the tank body and the feed pipe, The sulfuric acid storage tank according to Claim 1 or 2.

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