Gas exhaust mechanism

Abstract

To provide a gas discharge mechanism which can properly discharge a gas during an emergency.SOLUTION: A gas discharge mechanism includes: a first passage 11 which discharges a gas; a second passage 15 which is branched from the first passage; a control valve 20 which controls a flow of a gas to the second passage 15; and a control unit which controls operation of the control valve 20. The second passage 15 includes: a connection passage 15a in which its first end is connected so as to cover an opening formed on a side wall 12d of a bending part 12 formed by the first passage 11 bending; and a discharge passage 15b in which a second end of the connection passage 15a is connected to a side wall 15d and a communication opening 15c communicating with the second end of the communication passage 15a is provided on the side wall 15d. The control valve 20 includes: a valve body 21 which opens or closes the communication opening 15c; and a moving mechanism 23 which moves the valve body 21 between a closed position, where the valve body 21 is biased to the communication opening 15c of the discharge passage 15b, and an open position, where the valve body 21 is separated from the communication opening 15c of the discharge passage 15b, in accordance with commands from the control unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas exhaust mechanism, and more particularly to a gas exhaust mechanism for exhausting flammable gases such as hydrogen gas generated during the production of nickel sulfate, metal powder, etc., in a facility for producing nickel sulfate, metal powder, etc. [Background technology]

[0002] In nickel sulfate manufacturing facilities, nickel raw material in the form of briquettes and 70% sulfuric acid are supplied to a dissolution tank, and nickel sulfate is produced by dissolving the nickel raw material with sulfuric acid. The produced nickel sulfate is transported from the dissolution tank to the next process, where it is processed into products.

[0003] When nickel raw materials are dissolved in sulfuric acid, hydrogen gas is produced along with nickel sulfate. This hydrogen gas is discharged into the atmosphere by the gas exhaust mechanism. The gas exhaust mechanism is equipped with an exhaust duct and an exhaust fan (abatement tower), and the concentration of hydrogen gas in the dissolution tank is adjusted so as not to exceed the explosive concentration limit (4% or more) by controlling the flow rate of gas in the exhaust duct, i.e., the exhaust air volume, with the exhaust fan.

[0004] In nickel sulfate manufacturing equipment, even if the supply of nickel raw materials and sulfuric acid is stopped, the reaction that generates hydrogen gas cannot be stopped suddenly because the reaction proceeds naturally due to the raw materials in the dissolution tank. Therefore, if the exhaust fan of the gas discharge mechanism stops due to a disaster or power outage, the hydrogen gas concentration in the dissolution tank cannot be adjusted, and the concentration of hydrogen gas in the dissolution tank may increase and reach the explosion concentration limit. Therefore, the gas discharge mechanism is provided with an exhaust duct for emergency discharge (hereinafter sometimes referred to as the second exhaust duct) that is connected to the exhaust duct (hereinafter sometimes referred to as the first exhaust duct) in which the above-mentioned exhaust fan is provided, in addition to the exhaust duct in which the exhaust fan is provided. The second exhaust duct is provided with a valve in the middle of its flow path that blocks or opens the flow of gas in the second exhaust duct. Therefore, if the flow path of the second exhaust duct is blocked by the valve, the hydrogen gas discharged from the dissolution tank can be discharged to the atmosphere only through the first exhaust duct, and in an emergency, the hydrogen gas can be discharged to the atmosphere through the second exhaust duct by opening the valve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-519267 A Summary of the Invention [Problem to be solved by the invention]

[0006] As the valve to be provided in the flow path of the second exhaust duct, a spring-back type automatic valve may be provided (for example, Patent Document 1). However, the gas discharged from the dissolution tank contains nickel sulfate, and if such an automatic valve is provided in the middle of the second exhaust duct of the gas discharge mechanism in the nickel sulfate manufacturing facility as described above, at a location where the second exhaust duct is horizontal, there is a possibility that the automatic valve will become stuck and unable to open or close due to crystallization of nickel sulfate contained in the gas.

[0007] In view of the above circumstances, an object of the present invention is to provide a gas discharge mechanism that can appropriately discharge gas in an emergency. [Means for solving the problem]

[0008] The gas discharge mechanism of the first invention is A gas exhaust mechanism for exhausting hydrogen gas from a dissolving tank in a nickel sulfate manufacturing facility. The device includes a first flow path for discharging gas, a second flow path branched from the first flow path, a control valve for controlling the flow of gas to the second flow path, and a control unit for controlling the operation of the control valve. And, The second flow path includes a connecting flow path having a first end connected to cover an opening formed in a side wall of a bent portion of the first flow path, and a discharge flow path having a second end connected to the side wall and a communication opening in the side wall that is connected to the second end of the connecting flow path. The control valve includes a valve body that is provided so as to be able to approach and move away from the communication opening of the discharge flow path from an inner surface side of the discharge flow path and that opens and closes the communication opening, and a movement mechanism that moves the valve body between a closed position where the valve body is urged toward the communication opening of the discharge flow path in response to a command from the control unit and an open position where the valve body is moved away from the communication opening of the discharge flow path. The control unit detects a hydrogen gas concentration in the dissolution tank and controls the operation of the moving mechanism based on the detected hydrogen gas concentration. It is characterized by: A gas discharge mechanism of a second invention is the first invention, characterized in that an inner end surface of the communication opening of the discharge flow passage is formed as a conical surface whose diameter decreases from the inner surface to the outer surface of a side wall of the discharge flow passage, and the valve body is formed so that a side surface of the valve body is a conical surface whose diameter decreases toward a first end side of the connecting flow passage and a maximum diameter of the conical surface is larger than a maximum diameter of the inner end surface of the opening. 。 Effect of the Invention

[0009] According to the first invention, Since the first flow path and the second flow path can be connected according to the hydrogen gas concentration in the dissolution tank, the hydrogen gas concentration in the dissolution tank can be appropriately adjusted even if the function of discharging hydrogen gas from the first flow path is reduced. Moreover, even if the gas contains a component that bonds the valve body to the discharge flow passage, the movement of the valve body can be ensured. According to the second aspect of the present invention, the function of the valve body to close the communication opening of the discharge flow passage can be improved. [Brief description of the drawings]

[0010] [Figure 1] 1A and 1B are schematic explanatory diagrams of the control valve 20 of the gas discharge mechanism 10 of this embodiment, in which (A) is a schematic explanatory diagram of a state in which the communication opening 15c is blocked by the valve body 21, and (B) is a schematic explanatory diagram of a state in which the communication opening 15c is opened by the valve body 21. [Diagram 2] FIG. 1 is a schematic explanatory diagram of a facility 1 for producing nickel sulfate provided with a gas exhaust mechanism 10 of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The gas exhaust mechanism of this embodiment is a gas exhaust mechanism that exhausts gas containing flammable gas, and is characterized by being able to safely exhaust gas containing flammable gas even in emergencies, etc.

[0012] The equipment to which the gas exhaust mechanism of the present embodiment is applied is not particularly limited. For example, the equipment to which the gas exhaust mechanism of the present embodiment is applied may be an equipment for manufacturing nickel sulfate, metal powder, or the like. In addition, the flammable gas contained in the gas discharged by the gas discharge mechanism of the present embodiment is not particularly limited. For example, hydrogen gas or the like can be given as an example of the flammable gas contained in the gas discharged by the gas discharge mechanism of the present embodiment.

[0013] In the following, a case where the gas exhaust mechanism of the present embodiment is applied to a facility for producing nickel sulfate will be described as a representative example.

[0014] <Gas discharge mechanism 10 of this embodiment> As shown in Fig. 2, a nickel sulfate manufacturing facility 1 includes a dissolution tank 2 for dissolving nickel sulfate with sulfuric acid. The dissolution tank 2 is provided with a gas exhaust mechanism 10 for exhausting hydrogen gas generated in the dissolution tank 2.

[0015] As shown in Fig. 2, the gas exhaust mechanism 10 includes a first flow path 11 having one end connected to the dissolution tank 2. The other end of this first flow path 11 is open, and an exhaust fan 13 is provided in the flow path to cause the gas in the first flow path 11 to flow from one end to the other end. In other words, by operating the exhaust fan 13, the gas in the dissolution tank 2, that is, the gas containing hydrogen gas generated when nickel sulfate is dissolved by sulfuric acid, can be exhausted from the other end of the first flow path 11. As a result, the hydrogen gas concentration in the dissolution tank 2 can be reduced to a predetermined concentration or lower.

[0016] 1 and 2, a bent portion 12 is provided in the first flow path 11, and a first end of a communicating flow path 15a of the second flow path 15 is connected to an outer surface of a side wall 12d of the bent portion 12. Specifically, as shown in FIG. 1, the bent portion 12 of the first flow path 11 has an upstream flow path 12a that is connected to the dissolution tank 2, and a downstream flow path 12b that is provided perpendicular to the upstream flow path 12a. In the downstream flow path 12b, an opening is provided in a side wall 12d that intersects with the flow direction of the upstream flow path 12a, and a first end of a communicating flow path 15a of the second flow path 15 is connected to the outer surface (upper surface in FIG. 1) of the side wall 12d of the downstream flow path 12b so as to cover the opening.

[0017] As shown in FIG. 1, the second flow passage 15 is formed in a bent shape by the communication flow passage 15a and the discharge flow passage 15b. Specifically, the communication flow passage 15a is a flow passage provided so as to be substantially coaxial with the upstream side flow passage 12a of the first flow passage 11, and its first end (lower end in FIG. 1) is connected to the outer surface of the side wall 12d of the downstream side flow passage 12b of the first flow passage 11 so as to cover the opening. In addition, the side wall 15d of the discharge flow passage 15b is connected to the second end (upper end in FIG. 1) of the communication flow passage 15a. The side wall 15d of the discharge flow passage 15b is provided with a communication opening 15c that communicates the inside of the discharge flow passage 15b with the inside of the communication flow passage 15a, that is, the communication opening 15c that is a hole penetrating the side wall 15d. The communication opening 15c has an inner end surface 15f formed into a conical surface. More specifically, the communication opening 15c is formed such that its inner end face 15f has a diameter that decreases from the inner surface to the outer surface of the side wall 15d of the discharge flow passage 15b, in other words, from within the discharge flow passage 15b toward the communication flow passage 15a (downward in Figure 1).

[0018] <Control valve 20> As shown in FIG. 2, the control valve 20 includes a valve element 21 and a movement mechanism 22 that moves the valve element 21.

[0019] The valve body 21 opens and closes the communication opening 15c from the inner surface side of the discharge flow passage 15b, and is formed in a shape that allows the valve body 21 to airtightly close the communication opening 15c when the valve body 21 is placed in the communication opening 15c (see FIG. 1(A)). Specifically, the side surface 21f of the valve body 21 is formed in a conical surface whose diameter decreases toward the side wall 15d of the discharge flow passage 15b. Moreover, the side surface 21f of the valve body 21 is formed so that the minimum diameter da is smaller than the maximum diameter Da of the communication opening 15c and the maximum diameter db is larger than the maximum diameter Da of the opening. Therefore, when the valve body 21 is placed in the communication opening 15c, the communication opening 15c can be airtightly closed.

[0020] The valve body 21 is connected to an air cylinder 23 of the moving mechanism 22. Specifically, the air cylinder 23 has a cylinder body provided on the side wall of the discharge flow passage 15b (the upper side wall in FIG. 1), and its rod 23r is inserted into the discharge flow passage 15b through the side wall of the discharge flow passage 15b. The axial direction of the air cylinder 23 is parallel to the flow passage direction of the communication flow passage 15a (the flow passage direction of the upstream side flow passage 12a of the bent portion 12 of the first flow passage 11), and the valve body 21 is connected to the tip of the rod 23r of the air cylinder 23. When the air cylinder 23 is expanded, the valve body 21 is disposed in the communication opening 15c with the surface 21f pressed against the inner end surface 15f of the communication opening 15c (FIG. 1(A)), and when the air cylinder 23 is contracted, the valve body 21 is separated from the communication opening 15c to open the communication opening 15c (FIG. 1(B)). In other words, when the air cylinder 23 expands, the first flow path 11 and the second flow path 15 are airtightly blocked, and when the air cylinder 23 contracts, the first flow path 11 and the second flow path 15 are communicated. Note that the position where the valve body 21 is located when the air cylinder 23 expands is the closed position, and the position where the valve body 21 is located when the air cylinder 23 contracts is the open position.

[0021] 2, the air cylinder 23 is connected to a gas supply source 24 that supplies a working fluid to the air cylinder 23 via a flow path 24p. Also, the flow path 24p is provided with a supply control valve 25 that controls the supply of gas from the gas supply source 24 to the air cylinder 23. In other words, the extension and contraction of the air cylinder 23 is controlled by controlling the supply control valve 25.

[0022] <Control unit 30> As shown in Fig. 2, the gas discharge mechanism 10 of this embodiment includes a control unit 30 that controls the operation of the supply control valve 25, i.e., controls the extension and contraction of the air cylinder 23. The control unit 30 has a concentration sensor 31 that measures the hydrogen gas concentration in the dissolution tank 2 and a function of detecting the operation state of the exhaust fan 13. The control unit 30 normally has a function of controlling the operation of the supply control valve 25 so as to extend the air cylinder 23 and place the valve body 21 in a closed position. The control unit 30 has a function of controlling the operation of the supply control valve 25 so as to contract the air cylinder 23 and place the valve body 21 in an open position when the operation of the exhaust fan 13 stops or when the hydrogen gas concentration in the dissolution tank 2 exceeds a predetermined concentration (e.g., an explosion concentration limit).

[0023] <Operation of the gas discharge mechanism 10 of this embodiment> Since the gas discharge mechanism 10 of this embodiment has the above-mentioned configuration, when the hydrogen gas concentration in the dissolving tank 2 is maintained at or below a predetermined concentration, the supply control valve 25 is operated by the control unit 30 to maintain the air cylinder 23 in an extended state. Then, the first flow path 11 and the second flow path 15 are maintained in an airtight blocked state (hereinafter, sometimes simply referred to as a blocked state) by the valve body 21 of the control valve 20. In other words, the communication opening 15c of the side wall 15d of the discharge flow path 15b of the second flow path 15 is blocked by the valve body 21 of the control valve 20, so that the gas containing hydrogen gas in the dissolving tank 2 is discharged to the atmosphere through only the first flow path 11 by the exhaust fan 13 (see FIG. 1(A)). At this time, the exhaust fan 13 is controlled by the control device (or the control unit 30) of the facility 1 for producing nickel sulfate so that the hydrogen gas concentration in the dissolving tank 2 does not exceed a predetermined concentration (for example, the explosion concentration limit (4%)).

[0024] Even in the blocked state, a small amount of gas flows into the communicating flow path 15a, so there is a possibility that a small amount of gas discharged from the dissolution tank 2 may remain in the first flow path 11. However, since the amount of remaining gas is small, a situation does not occur in which the hydrogen gas concentration of the gas in the first flow path 11, i.e., the hydrogen gas concentration of the gas in the communicating flow path 15a, exceeds the explosion concentration limit (4%).

[0025] Furthermore, a small amount of gas flows into the communication flow passage 15a, causing the gas to come into contact with the valve element 21 of the control valve 20. However, in the blocked state, only the bottom surface (the lower surface in FIG. 1) of the valve element 21 of the control valve 20 that closes the communication opening 15c comes into contact with the gas. Therefore, even if the gas contains a component that bonds the valve element 21 to the discharge flow passage 15b, it is possible to prevent the valve element 21 from bonding to the discharge flow passage 15b.

[0026] On the other hand, when the control unit 30 detects that the exhaust fan 13 has stopped operating and / or that the hydrogen gas concentration in the dissolution tank 2 detected by the concentration sensor 31 has exceeded a predetermined concentration, it operates the supply control valve 25 so that the air cylinder 23 is in a contracted state (see FIG. 1(B)). Then, the communication opening 15c is opened, and the first flow path 11 and the second flow path 15 are in a communicated state (hereinafter, sometimes simply referred to as a communicated state), so that the hydrogen gas in the dissolution tank 2 is discharged to the atmosphere through both the first flow path 11 and the second flow path 15 or only the second flow path 15. In other words, even when the exhaust fan 13 has stopped operating, etc., if the communication state is established, the gas in the dissolution tank 2 can be discharged to the atmosphere through at least the second flow path 15, so that the hydrogen gas concentration in the dissolution tank 2 can be maintained at or below a predetermined concentration.

[0027] In addition, in the open state, when it is detected that the exhaust fan 13 has started to operate and / or that the hydrogen gas concentration in the dissolution tank 2 detected by the concentration sensor 31 has fallen below a predetermined concentration, the control unit 30 operates the supply control valve 25 to extend the air cylinder 23. Then, the open state can be returned to the shutoff state, and the facility 1 for producing nickel sulfate can be operated in a normal operating state.

[0028] Even when returning from the open state to the blocked state, gas remains in the communication flow passage 15a. However, in the blocked state, the amount of gas newly flowing into the communication flow passage 15a is small, so that it is possible to prevent the hydrogen gas concentration of the gas in the first flow passage 11, i.e., the hydrogen gas concentration of the gas in the communication flow passage 15a, from exceeding the explosion concentration limit (4%).

[0029] In addition, in the open state, gas comes into contact with not only the bottom surface of the valve body 21 of the control valve 20 but also the rod 23r of the air cylinder 23 and the like. Then, after returning from the open state to the shutoff state, the rod 23r of the air cylinder 23 may become stuck due to the gas components attached to the rod 23r during the open state, and the rod 23r of the air cylinder 23 may become stuck. If the rod 23r of the air cylinder 23 becomes stuck, it may not be possible to open the air cylinder 23 even if the control unit 30 detects that the exhaust fan 13 has stopped operating and / or that the hydrogen gas concentration in the dissolution tank 2 detected by the concentration sensor 31 has exceeded a predetermined concentration. Therefore, it is desirable to operate the air cylinder 23 periodically in order to check the operation of the rod 23r of the air cylinder 23 and to prevent the rod 23r of the air cylinder 23 from sticking.

[0030] <Regarding the control unit 30> If the concentration sensor 31 that detects the concentration of hydrogen gas breaks down, it may not be possible to appropriately control the hydrogen gas concentration in the dissolution tank 2. Therefore, the control unit 30 may be provided with a temperature sensor that measures the temperature of the gas in the first flow path 11 in addition to the concentration sensor 31 that measures the hydrogen gas concentration in the dissolution tank 2, and control the operation of the valve body 21 of the control valve 20 based on the measurement value of the temperature sensor (i.e., based on the temperature of the gas in the first flow path 11). For example, when the temperature of the gas in the first flow path 11 becomes a predetermined temperature or higher (e.g., 80°C or higher), the valve body 21 of the control valve 20 may open the communication opening 15c to communicate the first flow path 11 and the second flow path 15.

[0031] <Regarding the control valve 20> The air cylinder 23 of the moving mechanism 22 of the control valve 20 is not particularly limited in structure as long as it can move the valve body 21 between the closed position and the open position by expanding and contracting, and can maintain the state in which the communication opening 15c is closed by the valve body 21 at the closed position. As the air cylinder 23 of the moving mechanism 22 having such a function, it is preferable to use a spring-back type cylinder or an end-lock type cylinder. If such an air cylinder 23 is used, even if the operation of the gas supply source 24 stops due to a power outage or the like and it becomes impossible to supply the working fluid to the air cylinder 23, the valve body 21 can be automatically placed in the open position, and gas containing hydrogen gas can be reliably discharged in an emergency, so that the hydrogen gas concentration in the dissolution tank 2 can be prevented from exceeding a predetermined concentration.

[0032] The valve element 21 of the control valve 20 can improve the function of closing the communication opening 15c by forming the side surface 21f of the valve element 21 as a conical surface and forming the angle that the side surface 21f of the valve element 21 makes with respect to the central axis A (A in FIG. 1(A)) of the communication opening 15c at an angle that is approximately the same as the angle that the inner end surface 15f of the communication opening 15c makes with respect to the central axis A. The angle that the side surface 21f of the valve element 21 makes with respect to the central axis A and the angle that the inner end surface 15f of the communication opening 15c makes with respect to the central axis A may be different. Even in such a case, the function of the valve element 21 to close the communication opening 15c can be improved by providing the side surface 21f of the valve element 21 with a deformable material or forming the valve element 21 itself from a material that has a certain degree of deformability. For example, if the side surface 21f of the valve body 21 made of a base material such as stainless steel or iron is lined with an acid-resistant rubber such as EPDM, the function of the valve body 21 in closing the communication opening 15c can be improved.

[0033] The side surface 21f of the valve body 21 and the inner end surface 15f of the communication opening 15c do not necessarily have to be conical surfaces. If the bottom surface of the valve body 21 is brought into surface contact with the inner surface (upper surface in FIG. 1) of the side wall 15d of the discharge flow passage 15b, the function of the valve body 21 to close the communication opening 15c can be maintained. In addition, if a deformable material is provided on the bottom surface of the valve body 21 or the valve body 21 itself is made of a material that has a certain degree of deformability, the airtightness between the bottom surface of the valve body 21 and the inner surface of the side wall 15d of the discharge flow passage 15b can be improved. For example, if the bottom surface of the valve body 21 made of a base material such as stainless steel or iron is lined with rubber such as EPDM that is resistant to acid, the function of the valve body 21 to close the communication opening 15c can be improved. Furthermore, the airtightness between the bottom surface of the valve body 21 and the inner surface of the side wall 15d of the exhaust flow path 15b can be improved by providing a deformable material on the portion of the inner surface of the side wall 15d of the exhaust flow path 15b that comes into contact with the bottom surface of the valve body 21. For example, by lining the inner surface of the side wall 15d of the exhaust flow path 15b with rubber such as EPDM that is resistant to acid, the function of the valve body 21 to close the communication opening 15c can be improved. [Industrial Applicability]

[0034] The gas exhaust mechanism of the present invention is suitable as a gas exhaust mechanism for exhausting flammable gases such as hydrogen gas that are generated during the production of nickel sulfate, metal powder, etc. in facilities for producing nickel sulfate, metal powder, etc. [Explanation of symbols]

[0035] 1. Nickel sulfate manufacturing facility 2 Dissolution tank 10 Gas exhaust mechanism 11 First flow path 12 Bend 12a Upstream flow path 12b Downstream channel 12d side wall 13 Exhaust fan 15 Second flow path 15a Connecting channel 15b Exhaust flow path 15c opening 15d side wall 15f Inner end surface 20 Control valve 21 Valve body 21f side 22 Moving mechanism 23 Air Cylinder 23r Rod 24 Gas supply source 24p Flow path 25 Supply control valve 30 Control section 31 Concentration sensor

Claims

1. A gas exhaust mechanism for exhausting hydrogen gas from a dissolving tank in a nickel sulfate manufacturing facility, comprising: a first flow path for exhausting gas; A second flow path branched from the first flow path; a control valve for controlling the flow of gas to the second flow path; A control unit that controls the operation of the control valve, The second flow path is a connecting flow passage connected to the first flow passage such that a first end of the connecting flow passage covers an opening formed in a side wall of a bent portion of the first flow passage; a discharge flow passage having a communication opening in the side wall, the second end of the connection flow passage being connected to the side wall and communicating with the second end of the connection flow passage; The control valve is a valve body provided to be movable toward and away from the communication opening of the discharge flow passage from an inner surface side of the discharge flow passage, the valve body opening and closing the communication opening; a moving mechanism that moves the valve body between a closed position where the valve body is biased against the communication opening of the discharge flow path and an open position where the valve body is separated from the communication opening of the discharge flow path in response to a command from the control unit, The control unit is A hydrogen gas concentration in the dissolution tank is detected, and the operation of the moving mechanism is controlled based on the detected hydrogen gas concentration. A gas exhaust mechanism characterized by:

2. The communication opening of the discharge flow path is The inner end surface is formed into a conical surface whose diameter decreases from the inner surface to the outer surface of the side wall of the discharge flow path, The valve body is The side surface is a conical surface whose diameter decreases toward the first end side of the connecting flow passage, and the maximum diameter is formed to be larger than the maximum diameter of the inner end surface of the opening.

2. The gas exhaust mechanism according to claim 1.

Images