JP2020001961A - Heater for hydrogen sulfide reactor and manufacturing method therefor - Google Patents

Abstract

To provide a heater having enhanced corrosion resistance, usable even in a reactor exposed to high corrosion atmosphere, and a manufacturing method therefor.SOLUTION: There is provided a manufacturing method of a heater 12 used by impregnating the same into a melting sulfur S stored in a hydrogen sulfide reactor 10 for producing hydrogen sulfide by introducing a hydrogen gas to the melting sulfide S, for example consisting of an electric heater, in which a silicone acrylic coating containing an aluminum powder with a content of preferably 35 vol.% to 45 vol.% is applied to a surface of a stainless-made member, which becomes a liquid contact part with the melting sulfur S so that film thickness is preferably 40 μm to 50 μm, and then a galling coating is conducted by a heat treatment at suitably atmosphere temperature of 600°C or higher for 2 hrs. or longer.SELECTED DRAWING: None

Description

  The present invention relates to a heater installed at a position immersed in molten sulfur in a hydrogen sulfide reactor and a method for manufacturing the same.

  Hydrogen sulfide is an industrially important intermediate product. For example, as described in Patent Document 1, in a plant for treating nickel oxide ore by a hydrometallurgical process, low-grade nickel oxide ore is obtained by acid leaching. Hydrogen sulfide is used for the sulfurizing treatment of a sulfuric acid solution containing nickel and cobalt. Generally, hydrogen sulfide is industrially produced by recovering from hydrodesulfurization treatment of mineral oil or acid gas removal treatment of natural gas, or by reacting sulfur with hydrogen.

  In the latter production of hydrogen sulfide by the reaction between sulfur and hydrogen, for example, as described in Patent Documents 2, 3, and 4, gaseous sulfur is introduced by introducing hydrogen gas into sulfur in a molten state. It is common practice to generate hydrogen sulfide by an exothermic reaction of gasified sulfur and hydrogen in the gas phase.

  In order to increase the rate of reaction between sulfur and hydrogen and increase the yield of hydrogen sulfide, it is preferable to carry out the reaction at a higher temperature condition than the standard condition, and, depending on the use of the generated hydrogen sulfide, In some cases, it is necessary to supply hydrogen sulfide at a pressure of, for example, 500 kPaG or more. In this case, efficiency may be improved by generating hydrogen sulfide under the pressure condition of 500 kPaG or more. As described above, when hydrogen sulfide is generated under high-pressure conditions, the temperature of sulfur is maintained at a high temperature so that gasification of sulfur in a molten state proceeds sufficiently even under the high-pressure conditions.

JP 2010-126778 A Japanese Unexamined Patent Publication No. 2015-520111 WO 2013/027431 JP 2014-152090 A

  In the case where hydrogen sulfide is generated by the reaction between sulfur and hydrogen as described above, if the temperature condition at the time of the generation becomes 450 ° C. or higher, corrosion of the material of the reactor due to the generated hydrogen sulfide may become remarkable. Was. In particular, the heater that supplies heat for gasification of sulfur in the reactor is used in a state of being immersed in high-temperature molten sulfur, so the surface of the heater contains hydrogen gas and hydrogen sulfide gas. State sulfur will be in constant contact. Therefore, even when stainless steel, which is a corrosion-resistant material, is used as the material of the liquid contact portion on the surface of the heater, corrosion sometimes progresses due to a sulfurization reaction or the like by molten sulfur containing the above gas. Accordingly, there has been a demand for a reactor which is resistant to corrosion even when the inside of a reactor such as a hydrogen sulfide reaction tank is maintained under high temperature and high pressure conditions in order to secure a high reaction rate.

  Conventionally, in order to prevent corrosion of the liquid contact part of the heater, there has been a case where an alumina layer having resistance to sulfidation is provided on the surface of the stainless steel liquid contact part. Specifically, by applying a paint containing bituminous coal and aluminum powder to the surface of the wetted part made of stainless steel and then performing a bake coating that performs a heat treatment at about 1000 ° C., thereby providing an alumina layer on the stainless steel surface, Increasing the corrosion resistance of the stainless steel surface has been performed. However, this method has a problem that the temperature control is very difficult because the heat treatment conditions at the time of baking coating are as high as about 1000 ° C. There is also a problem that environmental pollutants such as SOx and NOx are generated during baking coating. The present invention has been made in view of the above circumstances, and has as its object to provide a heater which is hardly corroded even when installed inside a hydrogen sulfide reactor which is always exposed to a highly corrosive atmosphere.

  In order to achieve the above object, a method for producing a heater for a hydrogen sulfide reactor according to the present invention comprises the steps of: introducing hydrogen gas into molten sulfur to generate hydrogen sulfide; A method of manufacturing a heater to be immersed in a stainless steel member, characterized in that a silicon acrylic paint containing aluminum powder is baked on the surface of a stainless steel member to be in contact with the molten sulfur.

  Further, the heater for the hydrogen sulfide reactor according to the present invention is a heater that is used by being immersed in the molten sulfur stored inside the hydrogen sulfide reactor that generates hydrogen sulfide by introducing hydrogen gas into the molten sulfur. The surface of the stainless steel member which is in contact with the molten sulfur is baked and coated with a silicon acrylic paint containing aluminum powder.

  ADVANTAGE OF THE INVENTION According to this invention, even when it is immersed in molten sulfur in a hydrogen sulfide reactor in a highly corrosive environment, and a heater is used, corrosion of the liquid contact part can be suppressed.

It is a schematic structure figure of a hydrogen sulfide gas manufacture plant provided with a hydrogen sulfide reactor where a heater of an embodiment of the present invention is installed suitably. It is a photograph of the outer peripheral surface (a) of the half pipe | tube after baking coating used in the Example of this invention, and this when attached to an electric heater (b). 3 is a photograph of the outer peripheral surface of the short pipe after using the electric heater to which the short pipe of FIG. 2 is attached in a hydrogen sulfide reactor for one year.

  Hereinafter, a heater for a hydrogen sulfide reactor and a method for manufacturing the same according to an embodiment of the present invention will be described. First, a hydrogen sulfide gas production plant including a hydrogen sulfide reactor provided with a heater according to an embodiment of the present invention will be described with reference to FIG. A hydrogen sulfide gas production plant has a catalytic reaction system in which sulfur gas and hydrogen gas are reacted in a reactor filled with a catalyst, and a non-catalytic reaction system in which sulfur gas and hydrogen gas are reacted in a gas phase part without catalyst. It is mainly classified into the catalytic reaction type. In the following description, an example in which the heater of the embodiment of the present invention is employed in a reactor of a non-catalytic hydrogen sulfide gas production plant will be described. However, the present invention is not limited thereto. The heater according to the present invention may be employed.

  More specifically, the hydrogen sulfide gas production plant shown in FIG. 1 includes a reactor 10 for producing hydrogen sulfide gas from sulfur gas and hydrogen gas under high-temperature and high-pressure reaction conditions without using a catalyst; Cooling means 20a and 20b comprising a heat exchanger for cooling the hydrogen sulfide gas discharged from the top of the vessel 10 to, for example, about 50 ° C. using a coolant such as cooling water, and liquefied by the cooling means 20a and 20b A separating means 30 comprising, for example, a knockout drum or the like, for introducing a hydrogen sulfide gas containing sulfur to sediment droplet-shaped or granular sulfur by gravity and separating the sulfur from the hydrogen sulfide gas; and the cooling means 20a, 20b and the separating means And a blow-down means 40 for temporarily receiving the sulfur in a molten state extracted from the fuel cell 30. Note that the same devices are provided in parallel for the cooling means 20a and 20b, and by alternately operating them, it is possible to prevent clogging with sulfur.

  The hydrogen sulfide gas from which sulfur has been separated by the gas-liquid separation means 30 is transferred to, for example, a dezincing step or a sulfurizing step of a plant for treating the above-described nickel oxide ore by a hydrometallurgical method, and is used as a sulfide agent. You. On the other hand, the sulfur separated from the hydrogen sulfide gas by the cooling means 20a, 20b and the separation means 30 is deposited in a solidified state at the bottom, so that, for example, a steam or a steam provided on the outer peripheral portion on the lower side of the knockout drum is provided. The sulfur is then melted by the introduction of the sulfur and then transferred to the blowdown means 40. The molten sulfur transferred to the blowdown means 40 is transferred to a sulfur treatment plant using a supply pump 41 and processed there. The molten sulfur may be supplied to the reactor 10 and used repeatedly, for example.

  As described above, since most of the sulfur accompanying the hydrogen sulfide gas generated in the reactor 10 can be recovered by the cooling means 20a and 20b and the separation means 30, the plant to which the generated hydrogen sulfide gas is supplied can be recovered. In such a case, it is possible to prevent a problem that sulfur is attached to valves such as a control valve and a manual valve, and instruments such as a thermometer and a pressure gauge, which greatly hinders operation. In order to adjust the heat balance in the system of the reactor 10, the high-temperature molten sulfur extracted from the bottom of the reactor 10 is introduced into the sulfur cooling means 50, where it is cooled to, for example, about 150 ° C. Is supplied to the top of the reactor 10 via the circulation pump 51. The molten sulfur cooled by the cooling means 50 is transferred to the blow-down means 40 as needed.

  The hydrogen sulfide gas production plant of the non-catalytic reaction system described above does not require maintenance costs including initial costs for catalysts, costs for periodic replacement thereof, and costs for quality control, and also requires pressure control in the reactor 10 system. By setting the set value higher than the operating pressure of the plant to which the hydrogen sulfide gas is supplied, a compressor or a chiller facility for transferring the generated hydrogen sulfide gas to the plant to which the hydrogen sulfide gas is supplied becomes unnecessary. Therefore, there is an advantage that the operating cost can be reduced as compared with the catalytic reaction method.

  Next, the heater installed in the reactor 10 will be described. The reactor 10 of the hydrogen sulfide gas production plant includes a storage unit 11 for storing sulfur S in a molten state, an electric heater 12 installed so as to be immersed in the molten sulfur S in the storage unit 11, A gas phase section 13 for producing hydrogen sulfide gas using hydrogen gas blown into the molten sulfur S of the section 11 and sulfur gas generated by heating of the electric heater as raw materials; The quenching unit 14 mainly cools down to about 150 ° C. by bringing hydrogen sulfide gas into contact with molten sulfur of about 150 ° C. supplied from the top.

  The hydrogen sulfide gas generation reaction proceeds to some extent while the hydrogen gas introduced into the storage unit 11 passes through the molten sulfur S. The molten sulfur supplied from the top of the reactor 10 has a role of replenishing the sulfur in the system of the reactor 10 which is reduced by the reaction with the cooling of the produced hydrogen sulfide. The hydrogen sulfide gas discharged from the top of the reactor 10 includes molten sulfur which is entrained when the hydrogen gas passes through the molten sulfur S in the storage unit 11 and when the generated hydrogen sulfide gas passes through the quench unit 14. Contains.

  The reactor 10 of the hydrogen sulfide gas production plant having the above-described structure is operated under a high-temperature and high-pressure condition of, for example, an internal pressure of about 800 kPaG and an internal temperature of about 470 ° C. as a reaction condition for generating hydrogen sulfide gas. An electric heating coil was housed inside a stainless steel tube having a nominal diameter of about 50A to 100A in order to generate, from the molten sulfur S in the storage section 11, sulfur gas which is a raw material of the hydrogen sulfide gas generated under the high temperature and high pressure conditions. An electric heater 12 having a structure is inserted so as to penetrate the wall of the storage unit 11 of the reactor 10.

  The power supply of the electric heater 12 having the above structure is controlled by a control unit such as a CPU so that the temperature detected by a thermometer (not shown) provided in the reactor 10 is within a predetermined temperature range. Note that a plurality of electric heaters 12 may be installed according to the amount of sulfur gas generated in the storage unit 11. In the electric heater 12, the surface of the stainless steel tube in contact with the molten sulfur S is baked with a silicon acrylic paint containing aluminum powder. As a result, even when used under extremely severe corrosive conditions that are constantly in contact with high-temperature molten sulfur S containing hydrogen sulfide gas and hydrogen gas, almost no corrosion occurs.

  For the baking coating, for example, a coating material containing aluminum powder in a silicone acrylic coating material such as Solvalitt Aluminum manufactured by Jotun is prepared, and the coating film thickness (wet) is preferably about 40 to 50 μm. As described above, it is preferable that the application is performed by applying the liquid to the surface of the stainless steel tube by spray coating, and then heating at an ambient temperature of 600 ° C. or higher for 2 hours or longer. The reason for heating at 600 ° C. or more for 2 hours or more is that under these heat treatment conditions, an alumina layer can be deposited on the surface, and the corrosion resistance of the wetted surface of the stainless steel tube can be more reliably increased. is there. The upper limit of the ambient temperature during the heat treatment of the baking coating is preferably 700 ° C, more preferably 650 ° C. If the temperature exceeds 700 ° C., the properties of the coating film may change or the base material may be adversely affected. The upper limit of the heat treatment time is preferably 3 hours. This is because even if the heat treatment is performed for more than 3 hours, the anticorrosion performance hardly changes, and the heat treatment cost is rather increased.

  The reason for setting the coating film thickness (wet) to 40 to 50 μm as described above is that if the coating thickness is less than 40 μm, the corrosion resistance of the wetted portion may be insufficient. This is because the corrosion resistance is not so much improved and the cost is rather increased. In addition, since the film thickness of the silicon acrylic paint containing the aluminum powder hardly changes before and after the baking coating, the preferable film thickness of the coating (dry) after the baking coating is about 40 to 50 μm.

  The method for measuring the film thickness before and after the baking coating is not particularly limited, but the coating film thickness (wet) is preferably measured using, for example, a comb gauge of ISO 2808 Method 1A, and the coating after baking is preferably used. The thickness of (dry) is preferably measured, for example, in accordance with SSPC PA2. In addition, it is preferable to perform a visual appearance inspection in addition to the above-described film thickness measurement.

  It is preferable that the surface of the wetted portion of the stainless steel tube be subjected to, for example, a first undercoating of one kind of kelen and a second undercoating of alumite coating (metal spraying) before the baking coating. By such a base treatment, problems such as uneven coating and poor coating are unlikely to occur, and the effect of the baking coating can be reliably exhibited. Further, in the silicon acrylic paint containing aluminum powder used for the baking coating, the content of the aluminum powder is preferably 35% by volume or more and 45% by volume or less. When the content of the aluminum powder is within this range, it is possible to impart high corrosion resistance to the film after baking.

  As described above, the heater for the hydrogen sulfide reactor and the method of manufacturing the same according to the embodiment of the present invention have been described. However, the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention. Alternatives and modifications may be included. For example, the heater according to the embodiment of the present invention has been described on the assumption that the heater is an electric heater. However, a heater of a heat exchange system in which a heating medium having a higher temperature than molten sulfur is caused to flow inside a stainless steel tube to heat the stainless steel tube may be used. That is, the scope of rights of the present invention covers the claims and their equivalents.

[Example]
A stainless steel member obtained by baking and coating a silicon acrylic paint containing aluminum powder is exposed under substantially the same conditions as the liquid contact portion of the electric heater 12 of the reactor 10 in the hydrogen sulfide gas production plant having the configuration shown in FIG. In order to examine the corrosion resistance of the electric heater 12, a stainless steel tube having a size in which the inner peripheral surface is almost entirely in contact with the outer peripheral surface of the electric heater 12 is prepared. It was divided and fixed to the outer peripheral surface of the electric heater 12 with bolts. In this state, a hydrogen sulfide gas generation operation was performed for one year.

  Specifically, a short tube made of SUS310S having a nominal diameter of 50 A (outer diameter φ60.5 mm, inner diameter φ48.6 mm) is used for the stainless steel tube, and the outer peripheral surface side is a type of keren (blasting: a metal base is exposed). 1) and a second undercoating of a 200 μm-thick alumite coating (metal spraying). On the outer peripheral surface side on which the first and second base treatments have been performed, a sprayable silicon acrylic aluminum paint (model number Solvalitt Alu, aluminum powder content: 40 ± 2 vol%) is sprayed to a film thickness of 40 μm. It was applied by painting. The short tube after the application was held at an ambient temperature of 600 ° C. for 2 hours to perform baking coating as shown in FIG. 2A.

After the baking coating, the short pipe is halved, and a bolt fixing seat plate is attached to each half. As shown in FIG. 2 (b), the outer peripheral surface of the liquid contact portion of the electric heater 12 is almost entirely covered on the inner peripheral surface side. It was mounted so that it abuts. Then, a hydrogen sulfide gas generation operation was performed. At that time, the inner peripheral surface side of the half stainless steel tube was heated to about 550 ° C. by the electric heater 12. Further, the outer peripheral surface side of the half stainless steel tube was exposed to molten sulfur at about 450 to 500 ° C. containing hydrogen gas and H ₂ S gas.

[Comparative example]
For comparison, instead of the above-mentioned baking coating of the silicon acrylic aluminum coating, a coating containing bituminous coal and aluminum powder (manufactured by Sulzer Metco) (model number Metco Seal M) was applied by spray coating. The corrosion resistance was examined in the same manner as in the above example, except that the coating was baked by heat treatment over time. The composition of the paint used in this comparative example was such that aluminum powder was 25% and bituminous coal tar solvent was 75%, and this was applied according to Metco System11.

  As a result of exposing the baking-coated short pipes of the above-described Examples and Comparative Examples to a corrosive environment substantially similar to that of the electric heater 12 for one year, the baking-coated surfaces of the half-pipe short pipes of the Examples are comparative examples. Compared with the baked painted surface, no damage was caused by corrosion as shown in FIG. 3, and it was visually confirmed that the coating film was kept in a healthy state. Further, when the baking coating of the half-split short tube of the example was peeled off and the metal surface inside the coating film was visually observed, no corrosion or the like was observed, and a favorable state was maintained. From the above results, the baking-coated stainless steel tube of the example of the present invention is almost the same as the conventional one even when used for a heater of a reactor in a highly corrosive environment where a hydrogen sulfide gas generation reaction is performed. It can be seen that there is an excellent anticorrosion effect.

DESCRIPTION OF SYMBOLS 10 Reactor 11 Storage part 12 Electric heater 13 Gas phase part 14 Quench part 20a, 20b Cooling means 30 Separation means 40 Blow-down means 41 Supply pump 50 Sulfur cooling means 51 Circulation pump S Molten sulfur

Claims (6)

  A method for producing a heater which is immersed and used in the molten sulfur stored in a hydrogen sulfide reactor for generating hydrogen sulfide by introducing hydrogen gas into the molten sulfur, wherein the liquid contact portion with the molten sulfur is used. A method for manufacturing a heater for a hydrogen sulfide reactor, comprising baking a silicon acrylic paint containing aluminum powder on the surface of a stainless steel member to be formed.   The method for manufacturing a heater for a hydrogen sulfide reactor according to claim 1, wherein the silicon acrylic paint containing the aluminum powder has a content of the aluminum powder of 35% by volume or more and 45% by volume or less.   The heater for a hydrogen sulfide reactor according to claim 1 or 2, wherein the baking coating is performed after the silicon acrylic paint containing the aluminum powder is applied so as to have a film thickness of 40 µm or more and 50 µm or less. Method.   The baking coating is performed by subjecting a stainless steel member coated with the silicon acrylic paint containing the aluminum powder to a heat treatment at an ambient temperature of 600 ° C. or more for 2 hours or more, wherein the baking coating is performed. The method for producing a heater for a hydrogen sulfide reactor according to any one of the above.   A heater that is used by being immersed in the molten sulfur stored in a hydrogen sulfide reactor that generates hydrogen sulfide by introducing hydrogen gas into the molten sulfur, and is used as a liquid contact part with the molten sulfur. A heater for a hydrogen sulfide reactor, wherein a surface of a member made of a material is baked with a silicon acrylic paint containing aluminum powder.   The heater for a hydrogen sulfide reactor according to claim 5, wherein the stainless steel member is a tube of an electric heater accommodating a heat transfer coil inside.