Press-formed resin concrete panels for acid-resistant and heat-resistant tanks, and acid-resistant and heat-resistant panel inner lining method.

Abstract

To provide press-molded resin concrete panels with excellent acid resistance and heat resistance for repairing the inner walls of acid-resistant and heat-resistant tanks such as sulfur pits, and a panel inner-wrapping lining method using press-molded resin concrete panels with excellent acid resistance and heat resistance. [Solution] A press-molded resin concrete panel for acid-resistant and heat-resistant tanks, which has excellent acid resistance and heat resistance, for repairing the inner walls of sulfur pits, etc., is used in the panel inner-wrapping lining method. The press-molded resin concrete panel for acid-resistant and heat-resistant tanks 10 is made by mixing 10wt% to 15wt% vinyl ester resin as a binder, 40wt% to 60wt% sand as fine aggregate, and 30wt% to 40wt% clay (silica) as filler, and press-molding it at high temperature and high pressure.

Description

Technical Field

[0001] The present invention relates to a press-molded resin concrete panel excellent in acid resistance and heat resistance for repairing the inner wall of a sulfur pit or the like, and a panel inner winding lining method using the press-molded resin concrete panel excellent in acid resistance and heat resistance.

Background Art

[0002] A sulfur pit is a facility (such as a heavy oil desulfurization device) for safely treating gases containing hydrogen sulfide and sulfur compounds generated in the production and purification processes of sulfur. Sulfur pits are facilities that produce or treat sulfur and hydrogen sulfide in industries such as petroleum refining, natural gas processing, pulp and paper industry, and mining. They are widely used in industrial fields that safely treat and discharge dangerous hydrogen sulfide gas and reuse or dispose of the gases generated from the manufacturing and purification processes containing sulfur.

[0003] As a conventional maintenance method (preservation method) for sulfur pits, the repair of the acid-resistant mortar part applied to the concrete surface of the inner wall of the sulfur pit has been repeatedly carried out every 3 to 4 years to ensure soundness. However, as a result of conducting a core boring deterioration investigation of the side wall structure concrete, neutralization was observed in the entire cross-section of the structure thickness (the side wall structure concrete needs to be alkaline to prevent corrosion of steel bars, etc.), and it was found that the deterioration of the inner wall surface of the sulfur pit was progressing. Furthermore, due to aging deterioration of the side wall of the sulfur pit stored in a severe environment of 150°C to 160°C, there were situations where the acid-resistant mortar part bulged out, the reinforcement was exposed, and corrosion and reduction of the reinforcement were observed.

[0004] Patent Document 1 addresses the objective of "providing a corrosion-preventive composition containing vinyl ester resin that can be used as a corrosion-preventive coating material without the use of reinforcing materials and has excellent workability, and a method for protecting concrete structures using the same (Patent Document 1: Abstract)" and discloses "a corrosion-preventive composition containing vinyl ester resin A having a tensile elongation rate of 100-200% when cured, vinyl ester resin B having a tensile elongation rate of 1-20% when cured, a curing agent, and a curing accelerator (Patent Document 1: Abstract)." [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-085238 [Overview of the project] [Problems that the invention aims to solve]

[0006] According to Patent Document 1, a corrosion-preventive composition and method for protecting concrete structures (Patent Document 1: Title of Invention), it is possible to provide a vinyl ester resin-containing corrosion-preventive composition that can be used as a corrosion-preventive coating material without using reinforcing materials and has excellent workability, as well as a method for protecting concrete structures using the same. However, as in the present invention, applying it to facilities for safely treating gases containing hydrogen sulfide and sulfur compounds generated in sulfur production and purification processes, and to sulfur pits and other facilities that are in harsh environments exceeding 150°C, is likely to present problems in terms of performance and cost.

[0007] The object of the present invention is to provide a press-molded resin concrete panel with excellent acid resistance and heat resistance for repairing the interior walls of sulfur pits and the like, and a panel lining method using the press-molded resin concrete panel with excellent acid resistance and heat resistance. [Means for solving the problem]

[0008] To solve the above problems, the invention described in claim 1 is a press-molded resin concrete panel for acid-resistant and heat-resistant tanks, which has excellent acid resistance and heat resistance, for repairing the inner walls of sulfur pits and the like, This is a press-molded resin concrete panel for acid-resistant and heat-resistant tanks, characterized by containing 10 wt% to 15 wt% vinyl ester resin as a binder, 40 wt% to 60 wt% sand as fine aggregate, and 30 wt% to 40 wt% clay (silica) as filler.

[0009] The invention described in claim 2 is a process of removing existing mortar, which involves removing deteriorated acid-resistant mortar applied to a concrete surface forming an inner wall, The steel support assembly process involves installing steel supports along the inner wall (at predetermined intervals), A panel fixing steel installation process involves installing panel fixing steel materials on the aforementioned steel support structure, The panel installation process involves installing resin concrete panels onto the aforementioned panel fixing steel members, The system includes a grout injection process in which acid-resistant grout mortar is injected as backfill into the gap between the back surface (inner wall side) of the aforementioned resin concrete panel and the inner wall. The panel lining method is characterized by using the press-molded resin concrete panel for acid-resistant and heat-resistant tanks described in Claim 1 as the resin concrete panel. The press-molded resin concrete panel for acid-resistant and heat-resistant tanks described in Claim 1 refers to a press-molded resin concrete panel that is press-molded at high temperature and high pressure, with a blend of 10 wt% to 15 wt% vinyl ester resin as a binder, 40 wt% to 60 wt% sand as fine aggregate, and 30 wt% to 40 wt% clay (silica) as filler.

[0010] The invention described in claim 3 is the invention described in claim 2, wherein a silicone material with excellent heat resistance is used as a joint caulking material (sealant) to fill the gap (during installation) between the press-molded resin concrete panel for acid-resistant and heat-resistant tanks and the press-molded resin concrete panel for acid-resistant and heat-resistant tanks. As a backing material to support the aforementioned joint caulking material (sealant), polytetrafluoroethylene (PTFE), which has excellent heat resistance and acid resistance, is used. As the backfill grout material, acid-resistant grout mortar is used. This panel lining method is characterized by using fluororubber, which has excellent heat resistance and acid resistance, as a sponge rubber packing to prevent the backfill grout material from leaking out from the locations where the press-molded resin concrete panels for acid-resistant and heat-resistant tanks are fastened with countersunk bolts. [Effects of the Invention]

[0011] This invention relates to a press-molded resin concrete panel for acid-resistant and heat-resistant tanks, which has excellent acid resistance and heat resistance, for repairing the inner walls of acid-resistant and heat-resistant tanks, and to a panel lining method using the press-molded resin concrete panel for acid-resistant and heat-resistant tanks. The press-molded resin concrete panel for acid-resistant and heat-resistant tanks is a resin concrete panel that is press-molded at high temperature and high pressure, with a composition of 10 wt% to 15 wt% vinyl ester resin as a binder, 40 wt% to 60 wt% sand as fine aggregate, and 30 wt% to 40 wt% clay (silica) as filler.

[0012] A portion was cut (sampled) from a press-molded resin concrete panel for acid-resistant and heat-resistant tanks, processed, and immersed in a dilute sulfuric acid solution (20%, 60°C) for three months. After immersion, flexural strength, compressive strength, mass change rate, and erosion depth were measured. In short, environmental resistance tests were conducted regarding acid resistance (sulfuric acid) and heat resistance (60°C). As a result, in all test items—flexural strength, compressive strength, mass change rate, and erosion depth—very good results were obtained compared to a sample simulating a concrete interior wall with mortar application (interior wall of a conventional sulfur pit, etc.).

[0013] Therefore, by using press-formed resin concrete panels for acid-resistant and heat-resistant tanks, and a panel-wrapping lining method that utilizes these panels, the surface layer of the interior walls of sulfur pits, etc., becomes acid-resistant (and also heat-resistant), thus preventing the neutralization of the interior walls of sulfur pits, etc., that is, preventing the deterioration of interior walls of sulfur pits, etc., that require acid resistance and heat resistance. [Brief explanation of the drawing]

[0014] [Figure 1] This is a diagram showing the layout of a sulfur pit panel as an example of an acid-resistant and heat-resistant tank (top view (a), side view (b)). [Figure 2] This diagram illustrates the installation of press-formed resin concrete panels for acid-resistant and heat-resistant tanks. [Modes for carrying out the invention]

[0015] Hereinafter, an embodiment of the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks according to the present invention, and a panel lining method using the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks, will be described in detail with reference to Figures 1 and 2.

[0016] <Acid-resistant and heat-resistant press-molded resin concrete panels for tanks> The acid-resistant and heat-resistant press-molded resin concrete panel 10 for tanks according to the present invention is a press-molded resin concrete panel with excellent acid resistance and heat resistance. It is a resin concrete panel that is press-molded at high temperature and high pressure, with a composition of 10 wt% to 15 wt% vinyl ester resin as a binder, 40 wt% to 60 wt% sand as fine aggregate, and 30 wt% to 40 wt% clay (silica) as filler.

[0017] The press-molded resin concrete panel 10 for acid- and heat-resistant tanks is produced by kneading the fine aggregate, filler, etc., uniformly dispersing them in the binder, weighing a predetermined amount, pouring it into a mold, performing press working (including demolding), and curing to obtain a finished product (with a thickness of about 10 mm, a width of about 1000 mm, and a length of about 2000 mm: note that the dimensional values can be freely adjusted according to the mold dimensions). Note that the press-molded resin concrete panel can be easily cut to a predetermined size for the finished product due to its high workability, and drilling and curved surface processing can also be easily performed.

[0018] The press-molded resin concrete panel 10 for acid- and heat-resistant tanks is characterized by using clay (fine powder such as vermiculite, pottery stone, silica stone, sericite, etc.) because calcium carbonate, which is commonly used as a filler, easily reacts with acids. The components of clay are mainly silicate minerals, and silicate minerals are composed of silicon and oxygen and are usually also bonded to other elements such as aluminum, iron, magnesium, and calcium.

[0019] Minerals contained in clay include kaolinite, illite, montmorillonite, etc. Kaolinite, illite, montmorillonite, etc. contain a large amount of silica SiO2 (silicon dioxide), which is one of the most important components in refractory materials, and alumina Al2O3 (aluminum oxide), which is stable even at high temperatures and can maintain the structure of refractories. By containing a large amount of silica (silicon dioxide) and alumina (aluminum oxide), the heat resistance of the press-molded resin concrete panel 10 for sulfur pits is improved.

[0020] The clay (silica) blended as a filler in the press-formed resin concrete panel 10 for acid- and heat-resistant tanks preferably contains 55% to 70% by weight of silica SiO2 (silicon dioxide) and 15% to 25% by weight of alumina Al2O3 (aluminum oxide). Furthermore, it is desirable that the combined ratio of silica SiO2 (silicon dioxide) + alumina Al2O3 (aluminum oxide) is 70% to 80% by weight. Incidentally, depending on the environmental temperature and acid concentration to which the press-formed resin concrete panel 10 for acid- and heat-resistant tanks is applied, instead of clay, the use of clay minerals such as talc (talc; magnesium hydrosilicate), or the combined use of both may be possible and may be effective. Therefore, these may be adopted.

[0021] In order to improve heat resistance and acid resistance without impairing the function as a press-formed resin concrete panel, it is necessary to pay attention to the particle size distribution in order to blend as much clay as possible. To put it simply, if the particle size distribution is such that relatively small particles enter between relatively large particles, the packing ratio (bulk density) can be increased.

[0022] When various particle size distributions were tested, it was found that in order to improve heat resistance and acid resistance without impairing the function as a press-formed resin concrete panel, the particle size distribution that allows as much clay as possible to be dispersed while being blended, that is, the packing density (bulk density) becomes large, is as follows. It was found that it is sufficient if the particles in the particle size range within ±25% of the predetermined average particle size are 50% to 80% of the total number of particles. To show specific numerical values, for example, when the average particle size of the clay is 2 μm, it means that it is sufficient if the particles having a particle size in the range of 1.5 μm to 2.5 μm (±25% with respect to the average particle size) are 50% to 80% of the total number of particles in terms of the number.

[0023] <Inner Lining Method for Resin Concrete Panel> The resin concrete panel inlay lining method is a construction method that uses precast concrete panels (for example, press-molded resin concrete panels) for lining when reinforcing or repairing existing concrete structure waterways. The inner surface of the existing tunnel is covered with press-molded resin concrete panels, and grout material (mortar) is filled between the resin concrete panels and the inner surface of the existing tunnel, thereby reinforcing the inner surface of the tunnel with the press-molded resin concrete panels. In this invention, the panel inlay lining method is not performed on the inner wall surface of the existing tunnel, but on the inner wall surface of an acid-resistant and heat-resistant tank.

[0024] <Panel lining method using press-formed resin concrete panels for acid-resistant and heat-resistant tanks> Figure 1 is a layout diagram (top plan view and side view) of sulfur pit panels as an example of an acid-resistant and heat-resistant tank. Specifically, it is a layout diagram (top plan view (a) and side view (b)) in which sulfur pit panels are shown (on the top plan view and side view of the sulfur pit). Figure 2 is a diagram illustrating the installation state of press-molded resin concrete panels for acid-resistant and heat-resistant tanks.

[0025] A sulfur pit is a facility that temporarily stores gases containing sulfur compounds and converts them into harmless forms by oxidizing hydrogen sulfide through safe combustion or catalytic reactions. Typically installed underground, in the panel-in-lining method using press-molded resin concrete panels 10 for acid-resistant and heat-resistant tanks, as shown in Figure 1, press-molded resin concrete panels of approximately 1m x 1m are installed in a row on the inner walls (top, sides, and bottom) of a sulfur pit approximately 12m to 13m in length, 4m to 5m in width, and 4m to 5m in depth (see Figure 1).

[0026] The panel lining method using press-formed resin concrete panels 10 for acid-resistant and heat-resistant tanks comprises: an existing mortar removal step to remove existing mortar that has deteriorated due to strong acid and high heat after construction from the concrete surface forming the inner wall of the sulfur pit; a steel support assembly step to install steel supports 20 along the inner wall of the sulfur pit (at predetermined intervals); a panel fixing steel installation step to install panel fixing steel materials 30 on the steel supports 20; a panel installation step to install press-formed resin concrete panels on the panel fixing steel materials 30; and a step to inject backfill grout material (not shown) into the gap between the back of the press-formed resin concrete panel (sulfur pit inner wall side) and the inner wall of the sulfur pit (see Figure 2).

[0027] The press-molded resin concrete panel used is an acid-resistant and heat-resistant tank press-molded resin concrete panel 10, which is made by press-molding at high temperature and high pressure, with a mixture of vinyl ester resin as a binder (10 wt%) to 15 wt%), sand as fine aggregate (40 wt%) to 60 wt%), and clay (silica) as filler (30 wt%) to 40 wt%).

[0028] After removing the excess existing mortar applied to the concrete surface forming the inner wall of the sulfur pit (existing mortar removal process), the steel support structure 20 is installed along the inner wall of the sulfur pit as shown in Figure 2 (steel support structure assembly process). At this time, main reinforcement bars, distribution bars, and sheath pipes (tie rod steel attachment materials for the steel support structure to prevent it from tipping over after it is erected and fixed in place) are also installed on the inner wall of the sulfur pit.

[0029] Subsequently, the panel fixing steel members 30 are installed on the steel support structure 20 (panel fixing steel member installation process). In the panel fixing steel member installation process, equal-sided angle steel members (angle steel) are used as the panel fixing steel members, but as shown in Figure 2, flat bars installed on the fixing steel member installation hardware 40 may also be used as the panel fixing steel members 30. After that, the press-formed resin concrete panels 10 are installed by fixing them to the panel fixing steel members 30 using countersunk bolts. Furthermore, the work is completed by injecting backfill grout material into the gap between the back of the press-formed resin concrete panels 10 (sulfur pit inner wall side) and the sulfur pit inner wall (grout material injection process).

[0030] In the panel inlay lining method using press-molded resin concrete panels 10 for acid-resistant and heat-resistant tanks, acid-resistant grout mortar is used as the backfill grout material in the grout injection process to improve acid resistance. Acid-resistant grout mortar has a reduced cement content and is instead mixed with blast furnace fumes, blast furnace slag powder, fly ash, etc.

[0031] Furthermore, in the panel in-winding lining method using press-molded resin concrete panels for acid-resistant and heat-resistant tanks according to the present invention, a heat-resistant silicone material is used as a joint material (sealant) to fill the gap between the press-molded resin concrete panels for acid-resistant and heat-resistant tanks (during installation), and during the caulking work (filling the gap between panels with joint caulking material) in the panel in-winding lining method, the joint caulking material is applied to the back side (existing ton) of the press-molded resin concrete panel. Polytetrafluoroethylene (PTFE), which has excellent heat resistance and acid resistance, is used as a backup material, which is a flat plate-shaped member that holds the material in place so as not to be pushed out toward the panel side. Fluororubber, which also has excellent heat resistance and acid resistance, is used as a sponge rubber packing to prevent the backfill grout material from leaking out from the areas where the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks is fastened with countersunk bolts. This improves the heat resistance and acid resistance (during installation) of the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks itself.

[0032] <Effects of press-formed resin concrete panels for acid-resistant and heat-resistant tanks, and the panel-in-line construction method using press-formed resin concrete panels for acid-resistant and heat-resistant tanks> A portion of the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks was cut (sampled), the sample was processed, and then immersed in sulfuric acid solution (0% sulfuric acid (blank), 5% sulfuric acid, 20% sulfuric acid, all at 60°C) for 6 months. After that, the bending strength, compressive strength, mass change rate, and erosion depth were measured. The results showed that there was virtually no change in any of the test items (bending strength, compressive strength, mass change rate, and erosion depth), and no apparent discoloration was observed in the fracture surface.

[0033] In samples simulating mortar application to a (conventional) concrete interior wall surface, after immersion in dilute sulfuric acid solution (0% sulfuric acid (blank), 5% sulfuric acid, 20% sulfuric acid, all at 60 degrees Celsius) for three months, flexural strength, compressive strength, mass change rate, and erosion depth were measured. The results showed significant deterioration in all of the test items: flexural strength, compressive strength, mass change rate, and erosion depth. In short, samples from the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks were able to obtain better results (acid resistance and heat resistance) compared to samples simulating mortar application to a concrete interior wall surface.

[0034] Therefore, by using the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks, and the panel-wrapping lining method using the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks, the surface layer of the inner wall of the sulfur pit becomes acid-resistant (including heat-resistant), thus preventing the neutralization of the inner wall of the sulfur pit, that is, preventing the deterioration of the inner wall of the sulfur pit.

[0035] In the panel internal lining method (internal reinforcement type), if the amount of loss in the internal cross-section is not kept to a minimum (if a certain density is not ensured), the building limits will not be met. The press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks has high density (because it is manufactured by press molding) and is not affected by concrete carbonation. Furthermore, the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks has a process of injecting backfill grout material (acid-resistant grout material) into the gap between the back (existing concrete structure side) and the surface of the existing concrete structure. In this process, acid-resistant grout material (with a fine aggregate particle size of 1 mm or less) is filled, so it is no longer necessary to consider mortar cover (the distance from the framework to the surface to protect the framework of reinforcing bars etc. that are hardened with concrete or mortar) or the spacing between reinforcing bars (the minimum distance between reinforcing bars when embedding them in concrete).

[0036] Furthermore, while long-term durability is required for structurally strong components, the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks (because it is manufactured by press molding) ensures high density, preventing the intrusion of atmospheric carbon dioxide and sulfur dioxide from exhaust gases, which promote the neutralization of concrete components. Therefore, there is no need to set a margin for the neutralization region. As a result of the above, the panel in-winding lining method (in-winding reinforcement type) using the press-molded resin concrete panel 10 for acid-resistant and heat-resistant tanks can provide a structure that can obtain a large allowable stress even with a very small width dimension for the in-winding reinforcement cross-section.

[0037] <Examples of modifications to the panel lining method using press-formed resin concrete panels for acid-resistant and heat-resistant tanks, and press-formed resin concrete panels for acid-resistant and heat-resistant tanks> The acid-resistant and heat-resistant press-molded resin concrete panel for tanks, and the panel lining method using the acid-resistant and heat-resistant press-molded resin concrete panel according to the present invention, are not limited in any way to the embodiments described above. Each step, such as the removal of deteriorated existing mortar, the assembly of steel supports, the installation of panel fixing steel materials, the panel installation, and the grout injection, can be appropriately modified as necessary without departing from the spirit of the present invention. [Industrial applicability]

[0038] The press-molded resin concrete panel for acid-resistant and heat-resistant tanks, and the panel lining method using the press-molded resin concrete panel for acid-resistant and heat-resistant tanks according to the present invention, exhibit the excellent effects described above, and are therefore particularly suitable for use in panel lining methods when repairing acid-resistant and heat-resistant tanks. [Explanation of symbols]

[0039] 10. Acid-resistant and heat-resistant press-molded resin concrete panels for tanks. 20...Steel shoring 30. Panel fixing steel 40. Fixing steel frame installation hardware

Claims

1. A press-molded resin concrete panel for acid-resistant and heat-resistant tanks, which has excellent acid resistance and heat resistance, for repairing the interior walls of sulfur pits, etc. A press-molded resin concrete panel for acid-resistant and heat-resistant tanks, characterized by containing 10 wt% to 15 wt% vinyl ester resin as a binder, 40 wt% to 60 wt% sand as fine aggregate, and 30 wt% to 40 wt% clay (silica) as filler.

2. The process involves removing the deteriorated acid-resistant mortar applied to the concrete surface forming the inner wall of the acid-resistant and heat-resistant tank, and The steel support assembly process involves installing steel supports along the inner wall (at predetermined intervals), A panel fixing steel installation process involves installing panel fixing steel materials on the aforementioned steel support structure, The panel installation process involves installing resin concrete panels onto the aforementioned panel fixing steel members, The system includes a grout injection process in which acid-resistant grout mortar is injected as backfill into the gap between the back surface of the aforementioned resin concrete panel and the existing inner wall of the lining. An acid-resistant and heat-resistant panel inner-wrapping lining method characterized by using the press-molded resin concrete panel for acid-resistant and heat-resistant tanks described in claim 1 as the resin concrete panel.

3. As a joint caulking material (sealant) to fill the gap between the press-molded resin concrete panel for acid-resistant and heat-resistant tanks (during installation), a silicone material with excellent heat resistance is used. As a backing material to support the aforementioned joint caulking material (sealant), polytetrafluoroethylene (PTFE), which has excellent heat resistance and acid resistance, is used. As the backfill grout material, acid-resistant grout mortar is used. The acid-resistant and heat-resistant panel inner lining method according to claim 2, characterized in that fluororubber, which has excellent heat resistance and acid resistance, is used as a sponge rubber packing to prevent the backfill grout material from flowing out from the location where the press-molded resin concrete panel for acid-resistant and heat-resistant tanks is fixed with countersunk bolts.

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