JP2019105400A - Temperature control device of high pressure steam for autoclave feed, and temperature control method using the same - Google Patents

Abstract

To provide a temperature control method by which, even if the feed amount of high pressure steam varies owing to the variation of treatment conditions in an AC, an operation can stably be continued in the AC.SOLUTION: There is provided a temperature control method of high pressure steam fed to an autoclave via a steam feed line with a desuperheater. In the steam feed line, an insertion type thermometer 6 and a contact type surface thermometer 7 are installed within the range of 20 to 100 m from a water injection nozzle 2 of the desuperheater to the downstream side, and, in the case of a low load operation where the feed amount of the high pressure steam is 50% or lower of the designed flow rate of the desuperheater, the insertion type thermometer 6 is used, and in the case of a high load operation where the feed amount of the high pressure steam exceeds 50% of the designed flow rate, the contact type surface thermometer 7 is used.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a temperature control device for high pressure steam supplied to an autoclave and a temperature control method using the same.

  In a nickel smelting plant, high pressure acid leach (hereinafter also referred to as HPAL) autoclaves (hereinafter also referred to as AC) performing low pressure nickel oxide ore under high temperature / high pressure atmosphere using a large amount of high pressure steam. The leaching reaction of nickel (Ni) is performed by adding sulfuric acid. Since the inside of AC is thus exposed to severe corrosion conditions, high corrosion resistance materials such as titanium and duplex stainless steel are also used in the high pressure steam supply line connected to AC on the assumption of backflow of the reaction solution. The high temperature steam that is used has a temperature of 275 ° C to 280 ° C and a pressure of 5.0MPa, while the upper limit temperature at which these corrosion resistant materials can be used is around 290 to 300 ° C, which is close to the upper limit temperature of the above corrosion resistant materials Therefore, high temperature steam requires appropriate temperature control.

  For the high-pressure steam mentioned above, a bleed steam consisting of superheated steam generated from a multi-stage bleed-type steam turbine usually installed in a nickel smelting plant is used, and this bleed steam is used as a desuperheater (hereinafter (Also referred to as “H”) for temperature control, and then supplied to AC. In the above-described temperature reducer, temperature adjustment is performed by supplying the boiler feed water atomized to the extracted steam using a water injection (spray) nozzle. For example, as described in Patent Document 1, the supply amount of the boiler feed water is installed in the boiler feed line based on the measurement value of the thermometer installed downstream of the heat sink. It is adjusted to an appropriate amount by controlling the opening degree of the automatic valve.

Unexamined-Japanese-Patent No. 5-280707

  In the above-mentioned AC, it may be necessary to increase or decrease the supply amount of high pressure steam depending on the processing conditions of the HPAL process. For example, when the supply amount of high pressure steam is reduced to about half of the design flow rate, It has become difficult to control the temperature stably, and the HPAL process may not be performed at the desired processing conditions, which may cause product quality problems.

  The present invention has been made in view of the above-described conventional problems, and in the high pressure steam line, a plurality of thermometers of different measurement methods are installed downstream of the water injection nozzle of the temperature reducer, and these thermometers It is found that the temperature of high pressure steam can be stably controlled even in the case where the supply amount of high pressure steam is increased or decreased by appropriately selecting one to be used for temperature control of the temperature reducing device among the measured values of The present invention has been completed.

  That is, the temperature control method for high pressure steam for autoclaves according to the present invention is a method for controlling the temperature of high pressure steam supplied to an autoclave via a steam supply line provided with a temperature reducer, the temperature decrease in the steam supply line The insertion type thermometer and the contact type surface thermometer are installed in the range of 20m to 100m downstream from the water injection nozzle of the unit, and the amount of high pressure steam supplied is 50% or less of the design flow rate of the temperature reducer In the case of low load operation, the plug-in thermometer is used, and in the case of high load operation where the supply amount of the high pressure steam exceeds 50% of the design flow rate, the contact type surface thermometer is used. Do.

  Further, a temperature control device for high pressure steam for autoclave according to the present invention is a temperature control device for high pressure steam to be supplied to an autoclave through a steam supply line provided with a temperature reducer, the temperature decrease in the steam supply line A plug-in type thermometer and a contact type surface thermometer provided in the range of 20 m or more and 100 m or less on the downstream side from the water injection nozzle of the container, and selection means for selecting any one of the measurement values of these thermometers; Calculating means for calculating an opening degree of a flow control valve of water supplied to the water injection nozzle based on the measurement value selected by the selection means, the selection means reducing the temperature of the high-pressure steam supply For low load operation of 50% or less of the design flow rate of the heater, the plug-in type thermometer is used, and for high load operation where the high-pressure steam supply rate exceeds 50% of the design flow rate, the contact type surface Use a thermometer It is characterized in that.

  According to the present invention, even when the amount of supply of high-pressure steam is increased or decreased according to the process condition in AC, the process in AC can be stably continued.

It is a flow figure of a high-pressure steam system for AC supply provided with a temperature control device of an embodiment of the present invention.

  Hereinafter, an embodiment of a temperature control device for high pressure steam for autoclave supply according to the present invention and a temperature control method using the same according to the present invention will be described with reference to FIG. In the high pressure steam system for AC supply to which the temperature control device according to the embodiment of the present invention is suitably applied, the water injection nozzle 2 constituting the temperature reducer preferably has a spraying direction with respect to the high pressure steam line 1. It is provided to face the downstream side of the high pressure steam line. Boiler feed water is supplied to the water injection nozzle 2 through a supply line 3, and a flow control valve 4 is provided in the supply line 3 to adjust the feed amount of the boiler water supply to the water injection nozzle 2. Moreover, in the supply line 3, before and behind the said flow control valve 4, the primary side and secondary side manual valve 5a, 5b are provided, respectively.

  The temperature control device according to the embodiment of the present invention is in the range of 20 m to 100 m downstream of the water injection nozzle 2 in the high pressure steam line 1, preferably in the range of 25 m to 70 m, more preferably 30 m to 50 m. A plurality of thermometers with different measurement methods are provided within the following range. The plurality of thermometers are preferably provided separately in the flow direction of the high pressure steam. In FIG. 1, a plug-in type thermometer 6 and a contact type surface thermometer 7 are provided in this order along the flow direction of the high pressure steam line 1 so as to be separated from each other. Note that a plug-in type thermometer is a type of thermometer that measures the temperature of the fluid by placing the temperature detection unit of the temperature measuring means such as a thermocouple in a metal protective tube (sheath) and projecting it into the pipe The contact-type surface thermometer is a thermometer of a type in which the temperature detection unit is brought into contact with the outer surface of the pipe to measure the temperature of the fluid inside the pipe.

  The temperature measurement values measured by the two thermometers 6 and 7 are sent to control means 10 such as a program logic controller (hereinafter referred to as PLC) or a distributed control system (hereinafter referred to as DCS). The control means 10 selects selection means 11 for selecting one of the temperature measurement values from these two thermometers 6 and 7, and the flow control valve 4 based on the temperature measurement value selected by the selection means 11. And calculating the opening degree of the flow control valve 4 by the signal output from the calculating means 12. As a result, an appropriate amount of boiler feed water is supplied to the water injection nozzle 2 of the temperature reducer according to the temperature of the high pressure steam measured downstream of the temperature reducer.

  In the selection means 11 described above, when the supply amount of high pressure steam supplied to the AC is a low load of 50% or less of the design flow rate of the reducer, the insertion type thermometer 6 is used, and the supply amount of the high pressure steam is The choice is made to use the contact surface thermometer 7 if it exceeds 50% of the design flow of the cooler. As a result, high pressure steam can be stably supplied to AC even when, for example, the throughput of AC decreases and the supply volume of high pressure steam supplied to the AC falls below 50% of the design condition of the cooler. It becomes possible.

  The reason why high-pressure steam can be stably supplied in this way is as follows. That is, in temperature control using a plug-in thermometer, a good response corresponding to the amount of water injected from the water injection nozzle can be obtained in low load operation such that the high pressure steam flow rate of the temperature reducer is 50% or less of the design capacity However, if this design capacity exceeds 50%, adhesion of the water sprayed from the water injection nozzle to the protective tube becomes remarkable, and the temperature close to the saturated vapor temperature (266 ° C) is always displayed, and responsiveness Decreases. On the other hand, in temperature control using a contact-type surface thermometer, a temperature lower than the actual high-pressure steam temperature is always output as a measured value at 50% or less of the design capacity of the above-mentioned temperature reducer. Although it becomes difficult to perform, when the design capacity exceeds 50%, a good response can be obtained according to the amount of water injected from the water injection nozzle.

  The temperature control device according to the embodiment of the present invention monitors the steam temperature with a plurality of thermometers having different measurement methods as described above, in which case the trend of the measured values of the plurality of thermometers By comparing with the trend of the opening degree, it is possible to infer that there is a defect in the thermometer or a decrease in the atomization ability of the water injection nozzle 2 of the temperature reducer. That is, when the opening degree of the flow control valve 4 is adjusted based on the measurement value of the plug-in type thermometer 6, even if a problem occurs in the contact type surface thermometer 7 and an abnormal temperature is displayed, If the opening degree of the control valve 4 and the insertion type thermometer 6 are stably temperature controlled regardless of the display of the contact type surface thermometer 7, a problem occurs in the contact type surface thermometer 7. Can be guessed. In this case, for example, it may be checked at the time of the next periodic repair.

  On the other hand, when the opening degree of the flow control valve 4 is adjusted based on the measurement value of the plug-in type thermometer 6, a problem occurs in the plug-in type thermometer 6 and an abnormal temperature is displayed. Since the opening degree of the flow control valve 4 opens and closes based on the measurement value of the built-in thermometer 6, the temperature of the actual high pressure steam fluctuates and the fluctuation of the temperature of the actual high pressure steam is Since the flow control valve 4 continues to be adjusted by the temperature of the plug-in type thermometer 6 displayed and displayed independently of this, the value of the contact type surface thermometer 7 does not return to the desired set value and is abnormal It is possible to estimate that the plug-in type thermometer 6 has a failure, since it is necessary to keep displaying the various temperatures. In this case, the temperature measurement value used to control the flow control valve 4 may be switched from the insertion-type thermometer 6 to the contact-type surface thermometer 7, and the insertion-type thermometer 6 may be checked at the next periodic repair.

  In addition, when the atomization performance of the water injection nozzle 2 is lowered, a large number of water droplets sprayed in the vapor adhere to the protective tube of the temperature detection unit in the insertion type thermometer 6, and evaporation occurs there, so saturation occurs. A temperature close to the steam temperature will always be displayed. On the other hand, in the contact-type surface thermometer 7, even if the atomization performance of the water injection nozzle 2 is reduced, the water droplets hardly adhere, so the actual temperature of the high pressure steam is displayed. Therefore, by comparing these two temperature measurement values and referring to the trend of the temperature of these thermometers and the trend of the opening of the flow control valve 4 when the atomization performance has deteriorated in the past, as needed, The atomization performance of the water injection nozzle can estimate the occurrence of a decrease to some extent. EXAMPLES Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

[Example]
A plug-in thermometer (model number RTD) manufactured by TSSPL at a position 30m downstream from the water injection nozzle equivalent to three times the distance recommended by the temperature reducer manufacturer to the high pressure steam line for AC supply equipped with a temperature reducer. Contact temperature thermometer made by Okazaki Mfg. Co., Ltd. (Model FPN (Model No. FPN) at a position 50 m away from the water injection nozzle equivalent to 5 times the distance recommended by the temperature reducer manufacturer. R49N-EC)) was installed. The algorithm of DCS was constructed so that the measurement value to be used for temperature control could be selected from these two thermometers.

  And when the design capacity of the cooler is less than 50%, the measured value of the plug-in type thermometer is used when the load is less than 50%, and when the design capacity is more than 50%, the measured value of the contact type surface thermometer is used. The degree of opening of the flow control valve provided in the boiler feed water supply line supplied to the water injection nozzle of the cooler was controlled. In addition, the design capability of the used cooler, ie, the maximum design flow rate of high pressure steam, is 110 t / hr, so 50% of the design capability is the high pressure steam flow of 55 t / hr. The AC operation was performed with the high-pressure steam flow varied within the range of 50 to 110 t / hr while performing the above-mentioned temperature control. As a result, the control value (275 ° C.) ± 5 ° C. It became possible to control.

Comparative Example 1
A plug-in type thermometer was installed at a distance of 10 m downstream from the water injection nozzle, which is the recommended distance from the temperature reducer manufacturer, and the DCS algorithm was changed to use only the measured value of the thermometer for temperature control. The AC operation was performed in the same manner as in the above example. As a result, at the time of high load operation with a high pressure steam flow rate of 110 t / hr, a temperature close to the saturated steam temperature of 266 ° C. was always displayed, and temperature control could not be performed well.

Comparative Example 2
The AC operation was performed in the same manner as in the above example except that a plug-in type thermometer was provided in the AC and the DCS algorithm was changed so that only the measurement value of the thermometer was used for temperature control. As a result, since AC is located about 300 m downstream from the water injection nozzle of the temperature reducing device, the response of the water injection amount is delayed when the amount of steam used increases, and the steam of 20 ° C. for the control value of 275 ° C. A temperature rise occurred and the steam temperature could not be properly adjusted.

1 High-pressure steam line 2 Water injection nozzle of reducer 3 Boiler feed line 4 Flow control valve (automatic)
5a Primary side manual valve 5b Secondary side manual valve 6 Plug-in thermometer 7 Contact-type surface thermometer 10 Control means 11 Selection means 12 Calculation means

Claims (3)

  A temperature control method for high pressure steam supplied to an autoclave via a steam supply line including a temperature reducer, wherein the temperature of the steam supply line is in the range of 20 m to 100 m downstream from the water injection nozzle of the temperature reducer. A plug-in type thermometer and a contact type surface thermometer are installed, and the plug-in type thermometer is used in the case of low load operation where the supply amount of the high pressure steam is 50% or less of the design flow rate of the temperature reducer, A method for controlling the temperature of high pressure steam comprising using the contact-type surface thermometer in the case of high load operation where the supply amount of the high pressure steam exceeds 50% of the design flow rate.   The water supply amount supplied from the water injection nozzle of the temperature reducer is adjusted based on the temperature of the high pressure steam measured by the plug-in type thermometer or the contact type surface thermometer. The method of controlling the temperature of high pressure steam according to claim 1.   A temperature control device for high pressure steam supplied to an autoclave via a steam supply line provided with a temperature reducer, wherein the temperature control device is disposed in the range of 20 m to 100 m downstream of the water injection nozzle of the temperature reducer in the steam supply line. The water injection nozzle according to the provided plug-in type thermometer and contact type surface thermometer, selection means for selecting any one of the measurement values of these two thermometers, and the measurement value selected by the selection means Calculation means for calculating the degree of opening of the flow control valve of water supplied to the air conditioner, and the selection means is a low load operation in which the supply amount of high pressure steam is 50% or less of the design flow rate of The contact type surface thermometer is used in the case of a normal load operation in which the amount of supply of the high pressure steam exceeds 50% of the design flow rate using the plug-in type thermometer; Temperature control device.

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