JP6972607B2 - Flat valve control method, flat valve control system - Google Patents

Description

The present invention relates to a flat valve control method for adjusting the transfer of high temperature and high pressure fluid, and a flat valve control system.

In recent years, with the development of materials having effective corrosion resistance under high temperature and high pressure, the high pressure pressure acid leaching (HPAL) method using sulfuric acid is attracting attention as a hydrometallurgical method for nickel oxide ore. (See Patent Document 1).

The hydrometallurgical method of nickel oxide ore by the HPAL method is, for example, a step of making nickel oxide ore into a slurry to prepare an ore slurry (oriental slurry preparation step) and a step of adding sulfuric acid to the ore slurry and a pressure leaching reactor (a pressure leaching reactor (). Hereinafter, a step of leaching nickel and cobalt under high temperature and high pressure of 220 ° C. to 280 ° C. using (referred to as “autoclave”) to obtain a leaching slurry (leaching step), and a step of leaching residue and nickel and cobalt in the leaching slurry. A step of solid-liquid separation of the contained leachate (solid-liquid separation step), a step of neutralizing the leachate containing an impurity element together with nickel and cobalt to separate an impurity element such as iron (neutralization step), and neutralization separation. It includes a step of supplying hydrogen sulfide gas to the subsequent leachate to recover the nickel-cobalt mixed sulfide (sulfurization step).

In such a hydrometallurgical method, iron, which is a main impurity, is leached in the form of _{hematite (Fe 2} O ₃ ) by controlling the redox potential and temperature of the leachate in the autoclave in the leaching step of leaching. While fixing to the residue, nickel and cobalt can be selectively leached into the iron, which has a great advantage. The conditions of the leaching treatment in the autoclave vary depending on the conditions of the ore slurry, but the temperature condition is about 230 ° C. to 270 ° C., and the pressure condition is about 3 MPa to 5 MPa.

In hydrometallurgy for low nickel grade oxide ore using the high-pressure acid leaching method, the ore slurry is stepwise leached from the slurried ore (ore slurry) in order to selectively leach nickel and cobalt. The temperature is raised and increased to the top and transferred to the ore.

Then, after the leaching treatment is performed in the autoclave, the leaching slurry obtained after the treatment is gradually lowered in temperature and lowered to be transferred to the next step.

Specifically, in the process of lowering and lowering the temperature of the leaching slurry, for example, as in the processing system 10 for lowering and lowering the temperature shown in FIG. 1, three pressures in which the leaching slurry pushed up by the internal pressure from the discharge pipe 11 of the autoclave is installed in series The temperature is gradually lowered and lowered in the container (hereinafter referred to as “flash vessel”) 12 (12a, 12b, 12c). In such a temperature lowering step-down process, the ore slurry that has passed through the flash vessel 12 is finally lowered to a temperature of 100 ° C. or lower, and the pressure is lowered to atmospheric pressure.

When the leachate slurry is stepped down by the flash vessel 12, for example, the autoclave installed in the previous stage is provided by the control valve (control valve) 13 (13a, 13b, 13c) installed on the upper part of each flash vessel 12. The liquid level and the liquid level of the flash vessel 12a are controlled to be constant, and the leachate slurry is continuously extracted. Further, the liquid level of the flash vessel 12a in the front stage and the flash vessel 12b in the rear stage and the liquid level of the flash vessel 12b in the front stage and the flash vessel 12c in the rear stage are controlled to be constant, and the leaching slurry is continuously transferred.

Here, the leached slurry contains a large amount of high-hardness particles in addition to nickel, and is transferred at a high temperature and high speed due to the pressure difference between the flash vessels 12, so that the leached slurry is transferred to a container, a pipe, a valve, or the like. Has abrasion resistance. In addition, the leachate slurry is highly corrosive because it is acidified by sulfuric acid added in the autoclave.

Therefore, as the control valve 13 provided on the upper part of the flush vessel 12, a flat valve suitable for use of a leaching slurry, a corrosive fluid, a high-temperature high-pressure fluid, or the like is used. Further, due to the structure of the control valve 13, a ceramic material having excellent wear resistance is generally used as the material of the plug body and the seat component, which are rapidly worn. On the other hand, corrosion resistance is provided for wetted parts where it is difficult to use ceramic materials, such as the valve body (body), the plug stem that constitutes the shaft of the plug, and the bonnet that guides and holds the vertical sliding of the plug stem. Excellent titanium material is used. In the following, the control valve will be described as "flat valve 13".

In the process of lowering and lowering the temperature of the leached slurry using a flash vessel, the liquid level (liquid level) in the autoclave is usually measured by a sensor directly attached to the autoclave.

FIG. 2 is a schematic diagram showing an outline of liquid level control in the autoclave. The control of the liquid level in the autoclave is a balance between the flow rate of the slurry sent to the autoclave 20, the flow rate of the sulfuric acid supplied, and the flow rate of the leachate slurry sent to the flash vessel 12a installed after the autoclave 20. It is necessary to keep. Specifically, in the control of the liquid level in the autoclave 20, the liquid level of the leached slurry in the autoclave 20 is detected by the liquid level meter 21 installed behind the autoclave 20 so that the liquid level becomes constant. The valve opening degree of the flat valve 13a provided above the flush vessel 12a is adjusted.

For example, when the liquid level in the autoclave 20 is measured by the upper and lower limit liquid level sensors as the liquid level meter 21, when the liquid level rises and the liquid level sensor installed at the upper limit detects the liquid level, the flash flashes. The flat valve 13a provided on the vessel 12a is opened, and the leachate slurry staying in the autoclave 20 is discharged. Further, when the liquid level in the autoclave 20 drops and the liquid level sensor installed at the lower limit cannot detect the liquid level, the flat valve 13a provided in the flash vessel 12a is closed and the liquid level in the autoclave 20 is closed. The discharge of the leachate slurry is stopped. By controlling the liquid level by such a liquid level sensor, the liquid level of the leached slurry in the autoclave 20 is controlled between the upper limit position and the lower limit position.

Further, in the case of continuously measuring the liquid level, when the liquid level becomes higher than the control level, the leachate slurry staying in the autoclave 20 is increased by increasing the valve opening degree of the flat valve 13a provided in the flush vessel 12a. Increases emissions. Further, when the liquid level becomes lower than the control level, the discharge amount of the leached slurry from the inside of the autoclave 20 is suppressed by reducing the valve opening degree of the flat valve 13a provided in the flush vessel 12a.

However, the inside of the flat valve 13 provided in the flush vessel 12 inevitably wears if the use is continued due to the leaching slurry flowing at a high temperature and high speed, and the wear causes the valve body to wear. It is possible that the leachate slurry will penetrate and eject. Since the progress of such wear changes greatly depending on the operating state, it is necessary to periodically remove the flat valve 13 to check the state of the inside of the valve, repair according to the wear state, and replace parts.

Specifically, in the case of a flat valve, for example, the wear inside the flat valve 13 locally progresses around the plug body and around the plug stem where the flow of the leachate slurry is disturbed, and conventionally, the wear of the bonnet The plug and bonnet are frequently replaced due to wear of the plug insertion part and wear of the base of the plug stem. Further, depending on the progress of wear of these portions, there is a possibility that leakage of the leached slurry to the outside may occur due to a defect in the shaft seal portion. When replacing such valve parts, it is necessary to stop the equipment for a long time in order to reduce the temperature when the equipment is started down and to raise the temperature when the equipment is started up. Therefore, it is desired to suppress wear inside the valve to reduce the inspection cycle and the frequency of parts replacement.

Generally, in order to improve the wear resistance inside the flat valve, a protective film is formed by glass lining or ceramic spraying. For example, Patent Document 2 discloses an angle valve for a slurry having a glass lining inside the valve to improve corrosion resistance and wear resistance. However, the glass lining inside the valve may be damaged due to temperature changes, and scale objects adhering to the inside of the pipe and brick fragments lined on the inner wall of the tank flow into the valve together with the slurry to enter the inner wall. The glass lining may be easily damaged by the collision and may not exhibit sufficient wear resistance.

Further, Patent Document 3 discloses a slurry control valve for preventing peeling by spraying ceramic to a slurry control valve coated with a protective film and having a structure in which the adhered end portion of the protective film is not exposed. ing. However, even when this method is possible, the ceramic protective film is easily damaged by the collision of scale objects and bricks, as in the case of glass lining.

As described above, the conventional technique cannot sufficiently suppress the wear inside the valve due to the wear-resistant slurry. Actually, the life of the flat valve for controlling the level of the high-temperature and high-pressure slurry liquid is currently about 3 months in continuous operation. When replacing the flat valve during operation, it is necessary to reduce the temperature and pressure of the flush vessel, so that the operational loss is very large. From this point as well, a method for extending the life of the flat valve used is desired. In addition, the valve material that can withstand the flow rate of acidic slurry liquid at high temperature and high pressure is limited, and ceramic plugs are currently used, but they are very expensive, so the flat valve itself has a long life. It is desirable to make it.

For example, the flat valve for level control of the autoclave used in the leaching process of the hydrometallurgical method described above has a great influence on the manufacturing efficiency, cost, and ability of the process in continuous operation depending on the life of the flat valve.

Japanese Unexamined Patent Publication No. 2010-09489 Japanese Unexamined Patent Publication No. 5-118448 Japanese Unexamined Patent Publication No. 6-159528

The present invention has been proposed in view of such circumstances, for example, in a flat valve for adjusting the transfer of a high temperature and high pressure fluid to control the liquid level in the apparatus, wear or damage due to the fluid. It is an object of the present invention to provide a flat valve control method and a flat valve control system capable of extending the life by suppressing such factors.

The present inventor has made extensive studies to solve the above-mentioned problems. As a result, in the initial stage of the valve opening where the flow rate of the fluid to the flat valve suddenly increases, the flat valve is worn or damaged by the fluid by adjusting so that the rate of increase of the opening is relatively reduced. We have found that it can be effectively suppressed, and have completed the present invention.

(1) The first invention of the present invention is a method for controlling a flat valve for adjusting the transfer of a high-temperature and high-pressure fluid, wherein the flat valve includes a valve body and a plug slidable in the vertical direction. The plug is provided with a sheet for forming a fluid flow path, and the flow rate of the fluid is adjusted by opening and closing the opening of the flow path formed by the sheet based on the vertical sliding of the plug. This is a flat valve control method that relatively reduces the rate of increase in the opening degree in the opening portion at the initial stage when the opening operation is performed by separating the seat from the opening portion.

(2) In the second aspect of the present invention, in the first invention, the plug is composed of a plug body having a flat tip portion in contact with an opening of the flow path and a plug stem, and the plug body. This is a flat valve control method in which an opening / closing operation is performed in the opening by contacting or separating the tip portion of the valve from the opening.

(3) In the third aspect of the present invention, in the second invention, the upward sliding speed of the plug is set to a predetermined ratio at the initial stage when the plug body is separated from the opening and the opening operation is performed. It is a control method of a flat valve that relatively reduces the rate of increase of the opening degree in the opening by reducing the amount of the opening.

(4) In the fourth aspect of the present invention, in any one of the first to third inventions, the flat valve is a nickel oxide ore hydrometallurgical process in which the nickel oxide ore is subjected to sulfuric acid under high temperature and high pressure. It is a control method of a flat valve used for adjusting the transfer of the leaching slurry obtained by the leaching process.

(5) The fifth invention of the present invention is composed of a valve body, a plug body having a flat tip, and a plug stem, and forms a plug that slides in the vertical direction and a flow path having an opening. A flat valve control system that has a seat and regulates the transfer of inflowing high temperature and high pressure fluid through the flow path by abutting or separating the tip of the plug body from the opening. Therefore, an opening control unit for adjusting the sliding speed of the plug to control the opening degree of the opening is provided, and the opening control unit separates the plug main body from the opening to perform an opening operation. This is a flat valve control system that relatively reduces the rate of increase of the opening degree in the opening in the initial stage.

(6) In the sixth aspect of the present invention, in the fifth aspect, the opening control unit opens the opening by reducing the upward sliding speed of the plug by a predetermined ratio. It is a flat valve control system that relatively reduces the rate of increase.

According to the present invention, in a flat valve that controls the feeding of a fluid such as a high-temperature slurry, it is possible to suppress wear and damage due to the fluid and extend the service life.

It is a figure which shows typically the processing system of the temperature lowering pressure reduction. It is a schematic diagram which shows the outline of the liquid level control in an autoclave. It is sectional drawing which shows an example of the structure of a flat valve. It is a figure for demonstrating the shape of the plug (plug body) in a flat valve, and the flow of a slurry with respect to the plug. It is a graph which showed the relationship between the opening degree (%) in the opening of a flat valve, and the flow rate (m ^{3 / hr) of a slurry.} It is a figure which shows the flow of the control signal in the conventional control method of a flat valve. It is a figure which shows an example of the structure of the control system of a flat valve. It is a graph which shows the relationship between the input signal to a signal converter and the output signal from a signal converter, and is the input to the signal converter corresponding to the valve opening degree 0% to 100%, to the flat valve. The output coefficient is changed, and the control curve is changed so that the relationship between the valve opening and the slurry flow rate approaches a straight line. It is a graph which shows the relationship between the input signal to a signal converter and the output signal from a signal converter, and is the input to the signal converter corresponding to the valve opening degree 0% to 100%, to the flat valve. The output coefficient is changed, and the control curve is changed so that the relationship between the valve opening and the slurry flow rate approaches a straight line.

Hereinafter, a specific embodiment of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention.

≪1. Overview ≫
The flat valve control method according to the present embodiment is a flat valve control method used for adjusting the transfer of high-temperature and high-pressure fluid from the autoclave. Specifically, this method of controlling a flat valve relatively reduces the rate of increase in opening at the opening of the flat valve in the early stages of the opening operation, where the flow rate of fluid to the flat valve increases sharply. Specifically, it is characterized in that the opening operation of the opening is gradually performed so that the opening start time of the opening is longer than before.

According to such a method, it is possible to suppress a sudden change in the flow rate of the high-temperature fluid at the initial stage of the opening operation, and it is possible to reduce the influence of the temperature change on the flat valve. As a result, it is possible to reduce wear due to a rapid flow rate of the ceramic and deterioration due to thermal stress of temperature change, and it is possible to extend the service life.

As described with reference to FIGS. 1 and 2, the flat valve is provided in, for example, a flush vessel used in the leaching process of the wet trial process of nickel oxide ore by the HPAL method to regulate the transfer of the leached slurry. It can be applied to a control valve (valve). The flat valve is not limited to the equipment used in the hydrometallurgical process of nickel oxide ore.

Further, as described above, the target fluid to be transferred and adjusted by the flat valve is also the slurry used in the HPAL process, which is acidic in a high temperature state obtained by leaching with sulfuric acid under high temperature and high pressure. Slurry (leaching slurry) can be mentioned. The flat valve in the present embodiment can be effectively applied as a control valve for controlling the transfer of a corrosive fluid, a high-temperature and high-pressure fluid other than the above-mentioned leaching slurry, and the like, and here, these fluids. Is also included in the meaning of the term "slurry".

In the following, the flat valve 13 applied to the equipment used in the HPAL process (see FIGS. 1 and 2) will be taken as a specific example, and the leaching slurry having a high temperature and high pressure and being acidic (hereinafter, also simply referred to as “slurry”) will be given. The control of the flat valve in the case of coordinating the transfer of) will be described in detail.

≪2. Flat valve applied to flash vessel ≫
As shown in FIGS. 1 and 2, the flash vessel 12 (12a) lowers and lowers the temperature of the leached slurry obtained by acid leaching a metal such as nickel in the autoclave 20 under high temperature and high pressure conditions. Is for. A predetermined amount of leached slurry is transferred from the autoclave 20 to the flash vessel 12a while considering the liquid level of the leached slurry in the autoclave 20 in the previous stage.

At this time, the flat valve 13a provided on the upper part of the flush vessel 12a adjusts the transfer amount (flow rate) of the leached slurry from the autoclave 20 to control the transfer.

A plurality of flash vessels 12 can be provided, and for example, three flash vessels 12a, 12b, 12c are used to gradually lower the temperature of the slurry. Then, in the transfer of the leached slurry between the flash vessels 12, a predetermined amount of slurry is transferred to the flash vessel 12 in the subsequent stage while monitoring the liquid level of the flash vessel 12 in the previous stage in the same manner as described above. The leaching slurry flows at high speed between the flash vessels 12 due to the pressure difference.

FIG. 3 is a cross-sectional view showing an example of the configuration of the flat valve 13 provided on the upper part of the flush vessel 12. As shown in FIG. 3, the flat valve 13 includes a valve main body 31, a plug 32 slidable up and down, and a seat 33 forming a flow path of a slurry (fluid). The flat valve 13 is also referred to as a let-down valve because of its shape, and controls the slurry that has flowed in from the lateral direction (horizontal direction) to be dropped in the downward direction (vertical direction) and discharged.

[Valve body]
The valve main body 31 constitutes the main body of the flat valve 13, and the slurry flows inside the valve main body 31. The valve main body 31 is provided with a fluid inflow port 34 opened in the horizontal direction and a fluid outflow port 35 opened in the vertical direction, and each is connected to a pipe.

For example, as shown in FIG. 2, in the configuration in which the autoclave 20 and the flush vessel 12a provided with the flat valve 13a are connected, the slurry transferred from the autoclave 20 flows in from the fluid inflow port 34 through the pipe. Then, it flows at high speed inside the valve main body 31, passes through the flow rate control by the flat valve 13a, is discharged from the fluid outlet 35, and is transferred to the flash vessel 12b in the subsequent stage via the pipe.

[plug]
The plug 32 controls the outflow of the slurry flowing through the valve main body 31 by sliding in the vertical direction (arrow X direction in FIG. 3) inside the valve main body 31. Further, the plug 32 changes the opening degree of the opening 33p by abutting or separating from the opening 33p of the flow path formed by the sheet 33 described later, and the slurry flows out through the opening 33p. Control the flow rate of.

Specifically, the plug 32 is composed of a plug main body 32a and a rod-shaped plug stem 32b constituting a shaft.

The plug body 32a comes into contact with the opening 33p of the flow path of the slurry formed by the sheet 33 to close the opening 33p, thereby stopping the outflow of the slurry. The plug body 32a is made of, for example, a material such as ceramic, or the surface of the metal material is coated with a material such as ceramic to enhance its wear resistance.

The plug stem 32b constitutes the shaft of the plug 32, and the plug main body 32a is connected to the tip thereof, and the plug main body 32a is moved up and down by sliding upward or downward (arrow X direction). The plug stem 32b is surrounded by a bonnet 31a inside the valve main body 31 and can slide up and down by holding the guide by the bonnet 31a.

Note that FIG. 3 shows that the flow path of the slurry formed by the sheet 33 is closed by the plug 32. The opening and closing of the flow path by the plug 32 will be described in detail later.

[Sheet]
The sheet 33 forms a flow path of the slurry which is a fluid. The upper end of the flow path formed by the sheet 33 is an opening 33p in contact with the plug body 32a of the plug 32, and the slurry passing through the inside of the valve body 31 constitutes an inlet through the flow path. Therefore, the opening 33p opens and closes by bringing the plug 32 into contact with or separating from the opening 33p formed by the sheet 33. The sheet 33 has a shape in which the outflow flow rate of the slurry is almost stopped when the sheet 33 is fully closed by the contact with the plug main body 32a.

FIG. 4 is a diagram for explaining the shape of the plug 32 (plug main body 32a) in the flat valve 13, and the flow of the slurry with respect to the plug 32. As described above, in the flat valve 13, the plug 32 (plug body 32a) that slides in the vertical direction abuts on or separates from the opening 33p of the flow path of the slurry formed by the seat 33. As a result, the opening 33p is opened and closed. At this time, the shape of the tip of the plug 32 is flat in order to prevent the tip of the plug 32 from being chipped when the opening 33p is opened and the slurry is discharged. There is. However, with the plug 32 having such a flat tip shape, it is difficult to accurately and precisely control the flow rate of the slurry flowing out from the opening 33p. _{The arrows F 1} and F ₂ in FIG. 4 indicate the flow of the slurry.

Here, FIG. 5 shows a graph showing the relationship between the opening degree (%) at the opening and the flow rate (m ^{3 / hr) of the slurry.} In FIG. 5, the horizontal axis represents the valve opening degree (%), the vertical axis represents a typical flow rate (m ³ / hr), and the numerical value on the vertical axis shows the flow rate in a typical example. ing. This is an example when a flat valve similar to that shown in FIG. 3 is used.

As shown in FIG. 5, from the "closed state" (the state where the valve opening on the horizontal axis is 0%) in which the plug 32 (plug body 32a) having a flat tip shape is in contact with the opening 33p. By simply moving the plug 32 away from the opening 33p and slightly increasing the opening, the flow rate of the slurry increases sharply, and then the flow rate gradually increases. I understand. That is, since the area of the opening 33p suddenly expands at the beginning of opening, the flow rate of the slurry tends to flow out, and as the opening 33p opens, the increase in the flow rate of the slurry tends to reach a plateau.

From this, it can be said that in the control of the flat valve 13, it is difficult and unstable to control the flow rate of the slurry in the region of low opening.

FIG. 6 is a diagram for explaining the flow of control signals in the conventional control method of a flat valve. As shown in FIG. 6, in the control of a flat valve, for example, a controller 41 configured by a DCS (or a controller, a controller, etc.) converts a control signal as a value of a valve opening degree of 0% to 100%. Upon transmission to the positioner 42, the signal converter 42 converts the received control signal into a specific value commensurate with the valve opening between 0% and 100% and outputs it to the flat valve 13. In the conventional method, this relationship is generally output as a proportional relationship.

≪3. Flat valve control method ≫
FIG. 7 is a diagram showing an example of the configuration of a flat valve control system. The control system 1 includes a flat valve 13 provided in the process pipe 50 through which the slurry flows, an opening control unit 2 that adjusts the sliding speed of the plug 32 of the flat valve 13 to control the opening degree of the opening 33p, and an opening degree control unit 2. It is provided with a signal converter (positioner) 3 that receives a control signal from the opening degree control unit 2, converts the signal into a specific numerical value, and gives an opening degree instruction to the flat valve 13.

Further, the control system 1 has an information signal regarding the flow meter 4 for measuring the actual flow rate of the slurry passing through the process pipe 50 via the flat valve 13 and the slurry level of the upper device such as the liquid level of the slurry in the autoclave 20. Is provided with a higher-level system 5 that sends the signal to the opening degree control unit 2.

Specifically, in the control system 1, for example, the flat valve 13 is attached to the flat valve 13 which is a control valve that regulates the flow rate of the slurry sent from the autoclave 20 which is a higher-level device to the flash vessel 12a. The signal converter 3 sends an instruction on the valve opening degree, and the opening degree is adjusted. The signal converter 3 detects the actual opening degree of the flat valve 13, and valves so that the actual opening degree of the flat valve 13 matches the control signal (S1) regarding the opening degree sent from the opening degree control unit 2. Adjust the opening of.

Further, in the control system 1, the host system 5 imparts an information signal (S2) at the slurry level in the autoclave 20 to the opening degree control unit 2. The opening degree control unit 2 compares the information signal (S3) regarding the actual slurry flow rate of the process fluid measured by the flow meter 4 with the slurry level information signal (S2) sent from the host system 5. The opening degree at the opening 33p of the flat valve 13 required to match the two is obtained as the opening degree instruction value θ_SP. The control signal (S1) relating to the opening degree instruction value θ_SP obtained by the opening degree control unit 2 is sent to the signal converter 3. The signal converter 3 detects the actual opening degree θ_PV at the opening portion 33p of the flat valve 13, so that the actual opening degree θ_PV of the flat valve 13 coincides with the opening degree indicated value θ_SP sent from the opening degree control unit 2. Adjust the opening.

At this time, in the control system 1 according to the present embodiment, at the initial stage when the opening control unit 2 separates the plug main body 32a of the flat valve 13 from the opening 33p and performs the opening operation, the opening in the opening 33p. It is characterized by a relative decrease in the rate of increase.

Specifically, as a method of relatively reducing the opening speed, the plug 32 is opened by sliding it upward from the closed state in which the plug body 32a is in contact with the opening 33p. In the initial stage of the operation, the sliding speed is reduced by a predetermined ratio so that the plug body 32a is gradually and slowly separated from the opening 33p, and the increasing speed of the opening in the opening 33p is relative. To reduce.

Here, the opening speed increasing speed means the opening speed of the opening 33p that expands by separating the plug 32 from the opening 33p. Further, to relatively decrease the increasing speed of the opening, for example, to make it slower than the increasing speed when compared with the increasing speed of the opening in a stage other than the initial stage in which the opening operation is performed. To say.

Further, in reducing the sliding speed, for example, when the sliding speed at the time of closing the opening 33p in which the plug 32 is slid downward and brought into contact with the opening 33p is used as a reference, the sliding speed is reduced. The plug 32 is operated at a speed reduced by a predetermined ratio from the reference sliding speed.

According to such a control method by the control system 1, it is possible to prevent the control at the opening start portion of the opening 33p from becoming unstable, and as in the conventional control method, at the initial stage thereof. It is possible to prevent the flow rate of the slurry from increasing rapidly. This makes it possible to suppress damage to the inside of the flat valve 13 due to a rapid flow of slurry. Further, since the rapid inflow of the high-temperature slurry can be prevented, the influence of the temperature change related to the life of the plug 32 of the flat valve 13 can be reduced.

For example, FIG. 8 is a diagram showing the relationship between the input to the signal converter 3 and the output from the signal converter 3, with respect to the input to the signal converter 3 according to the valve opening degree of 0% to 100%. Therefore, the output coefficient to the flat valve 13 is changed, and the control curve is changed so that the relationship between the valve opening degree and the slurry flow rate approaches a straight line. The horizontal axis represents the input signal (control signal) according to the opening degree (0% to 100%) to the signal converter 3, and the vertical axis represents the opening degree (0) from the signal converter 3 to the flat valve 13. % ~ 100%) represents an output signal.

As shown in FIG. 8, in the region where the input value is low (the region on the left side of the graph) with respect to the valve opening command, the output signal (opening output) to the flat valve 13 is lower than the input signal. It has become. In this region, the opening degree control unit 2 controls the output signal to be kept low in order to prevent a sudden increase in the opening degree of the valve. For example, when 40% of the input is input, 22% of the output is output. In this way, by reducing the sliding speed of the plug 32 so that the output is 22% with respect to the input of 40%, the increasing speed of the opening at the opening 33p is reduced, and from FIG. As calculated, the slurry flow rate is set to about 500 m ³ / hr.

Assuming that the magnitudes of the input signal and the output signal are proportional to each other and the output is 40% with respect to the input of 40%, the slurry flow rate becomes as large as ^{700 m 3 / hr.}

Further, in FIG. 9, the coefficient in the region where the input value is low (low opening region) is emphasized lower than in the example of FIG. 8, and the opening is set so as to change more slowly. This is an example. By doing so, the control of the valve in the low opening region becomes finer, and the valve can be operated slowly. Then, by controlling slowly, the thermal change to the plug 32 can be reduced, the influence of thermal stress can be suppressed, and the life of the flat valve 13 can be extended.

Here, in the relationship between the input signal (control signal) to the signal converter 3 and the output signal from the signal converter 3 to the flat valve 13 in the initial stage when the plug 32 is separated from the opening 33p and the opening operation is performed. , The output signal can be expressed by the product of specific coefficients with respect to the input signal, as expressed by the following equation (1).
Output signal = input signal x coefficient ... (1)

The coefficient can be set so as to be summarized in Table 1 below according to, for example, the opening degree of the valve which is an input signal. This coefficient is based on the examples of FIGS. 8 and 9.

Hereinafter, specific examples to which the present invention is applied will be described, but the present invention is not limited to these examples.

[Example 1]
When the slurry from the autoclave was sent to the flush vessel, the slurry flow rate was controlled by a flat valve provided on the upper part of the flush vessel.

Similar to the one illustrated in FIG. 3, the flat valve includes a valve body, a plug slidable in the vertical direction, and a sheet forming a fluid flow path, and the flow path formed by the sheet. By opening and closing the opening of the plug based on the vertical sliding of the plug, the flow rate of the slurry can be adjusted.

Further, in the control of the slurry flow rate by the flat valve, the opening control unit that controls the opening degree of the opening by adjusting the sliding speed of the plug and the control signal from the opening degree control unit are received and the signal is received. A control system equipped with a signal converter that converts to a specific value and gives an opening instruction to the flat valve was used.

Then, in the first embodiment, in the initial stage of performing the opening operation by separating the plug from the opening, the operation is performed so as to relatively reduce the increasing speed of the opening in the opening. Specifically, the opening / closing operation was performed by reducing the sliding speed of the plug in the flat valve so that the output signal to the flat valve had a control curve as shown in FIG.

[Comparative Example 1]
In Comparative Example 1, the sliding speed of the plug in the flat valve is not controlled based on the conventional control method, and the flat valve is opened and closed while keeping the relationship between the valve opening degree and the slurry flow rate as shown in FIG. The operation was performed.

Table 2 below shows the calculation results of the average life of each flat valve used in Example 1 and Comparative Example 1.

As can be seen from the results shown in Table 2, the flat valve operated as in Example 1 has a significantly longer life expectancy than the flat valve operated as in Comparative Example 1. This is because, in Example 1, in the initial stage of the opening operation in which the flow rate of the slurry suddenly increases, the rate of increase in the valve opening is relatively reduced, so that the plug or the like is damaged by the high temperature slurry. Is thought to have decreased. On the other hand, in Comparative Example 1, since the cracks generated on the ceramic surface of the plug grew due to the thermal stress due to the control of the high temperature slurry based on the sudden opening / closing operation, the life was only 3 It is thought that it has been about a month.

1 Control system 2 Opening control unit 3 Signal converter 4 Flow meter 5 Upper system 10 Processing system 11 Discharge piping 12, 12a to 12c Flash vessel 13, 13a to 13c Flat valve (control valve)
20 Autoclave 21 Liquid level meter 31 Valve body 31a Bonnet 32 Plug 32a Plug body 32b Plug stem 33 Seat 33p Opening 34 Fluid inlet 35 Fluid outlet 41 Controller 42 Signal converter 50 Process piping

Claims (5)

A flow path for transferring a leachate slurry, which is a high-temperature and high-pressure fluid obtained by leaching the nickel oxide ore with sulfuric acid under high temperature and high pressure in a wet smelting process of nickel oxide ore, to a facility installed on the downstream side. It is a control method of the flat valve provided in
The flat valve is
A valve body provided with a fluid inlet opened in the horizontal direction and a fluid outlet opened in the vertical direction.
A plug that can slide up and down,
A sheet having an opening and forming a flow path for the fluid flowing out to the fluid outlet is provided.
The plug in the flat valve
The plug body is composed of a plug body having a flat tip portion in contact with the opening of the flow path formed by the sheet and a plug stem, and the plug body is located on the upstream side of the opening of the flow path. wherein disposed within the valve body,
The flow rate of the fluid flowing from the fluid inlet in the valve body to said fluid outlet, the sliding contact or is spaced apart in the opening of the distal end portion of the plug body-out based on the in the vertical direction of the plug adjusted by opening and closing operation of the opening Te,
A method for controlling a flat valve that relatively reduces the rate of increase of the opening in the opening at the initial stage when the plug is separated from the opening of the seat and the opening operation is performed. In the initial stage when the plug body is separated from the opening and the opening operation is performed, the upward sliding speed of the plug is reduced by a predetermined ratio, so that the increasing speed of the opening in the opening is relative. The method for controlling a flat valve according to claim 1. A flow path for transferring an leached slurry, which is a high-temperature and high-pressure fluid obtained by leaching the nickel-oxidized ore with sulfuric acid under high-temperature and high-pressure in a wet smelting process of nickel-oxidized ore, to a facility installed on the downstream side. It is a flat valve control system installed in
The flat valve is
A valve body provided with a fluid inlet opened in the horizontal direction and a fluid outlet opened in the vertical direction.
A sheet having an opening and forming a flow path to flow out to the fluid outlet,
The plug body is composed of a plug body having a flat tip portion in contact with the opening of the flow path formed by the sheet and a plug stem, and the plug body is located on the upstream side of the opening of the flow path. wherein disposed within the valve body, a plug which slides vertically,
Have,
The tip of the plug body is brought into contact with or separated from the opening to open and close the opening , thereby adjusting the transfer of the inflowing high-temperature and high-pressure fluid through the flow path. The control system
An opening control unit for adjusting the sliding speed of the plug to control the opening of the opening is provided.
The opening control unit is a flat valve control system that relatively reduces the increasing speed of the opening in the opening at the initial stage when the plug body is separated from the opening and the opening operation is performed. The flat valve control system according to claim 3 , wherein the opening control unit reduces the upward sliding speed of the plug at a predetermined rate to reduce the increasing speed of the opening in the opening. .. The control system is
A signal converter that converts into an instruction signal based on the control signal from the opening control unit and gives an opening instruction to the flat valve.
A flow meter that measures the flow rate of the fluid flowing out into the pipe through the flat valve, and
A higher-level system unit that sends an information signal regarding the fluid level of the higher-level device that causes the fluid to flow into the flat valve to the opening degree control unit is further provided.
The opening control unit
The flow rate information signal regarding the flow rate measured by the flow meter is compared with the information signal sent from the higher-level system unit to obtain an opening degree indication value.
When adjusting the opening so that the opening instruction value and the actual opening of the flat valve match, the opening in the opening is initially performed by separating the plug body from the opening and performing the opening operation. The flat valve control system according to claim 3 or 4 , wherein the growth rate of the flat valve is adjusted to be relatively reduced.

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