JP5065916B2 - Low-pressure steam supply device and pressure control method in this steam supply device - Google Patents

Description

  The present invention relates to a low-pressure steam supply apparatus and a pressure control method in the low-pressure steam supply apparatus that can control a header pressure of a steam header in a plant or the like and provide steam having a stable pressure.

  Conventionally, various plants such as petrochemical complexes have various steam (steam) generation sources, and the steam generated from these steam generation sources is used in various apparatuses. Some steam generation sources, such as boilers, generate steam intentionally, and others generate secondary steam. In various plants, the steam from the plurality of steam generation sources is distributed effectively to various devices that require steam, such as generators and heating facilities, for effective use. In various apparatuses using steam, in addition to being used with the high pressure generated by the steam generation source, the apparatus is supplied while being decompressed to a low pressure suitable for use, that is, a pressure lower than that of the steam generation source.

  By the way, when a device using a plurality of steams is connected, the required amount of steam supplied also changes according to the amount of steam used in each device. Therefore, one pressure controller is provided between a plurality of steam generation sources and various devices so that the pressure remains constant even when the usage amount changes, and any one steam generation source is provided by the pressure controller. The amount of supply from was controlled, and the remaining steam generation sources were kept constant. However, in the control of the supply amount from the one steam generation source, it is difficult to supply the steam required by each device without excess or deficiency so that the pressure is constant.

Japanese Patent Laid-Open No. 04-128505

  Then, this invention is made | formed in view of the above situations, and it aims at providing the pressure control method in this low-pressure steam supply apparatus which can perform stable pressure control, and this low-pressure steam supply apparatus. To do.

  In order to solve the above-described problem, the low-pressure steam supply apparatus according to the present invention is supplied with the first steam from the first steam source and the second steam from the second steam source, A pressure header for storing the second steam as low-pressure steam and supplying the low-pressure steam to the outside; and a first steam adjusting means for adjusting a supply amount of the first steam supplied from the first steam source; The second steam adjusting means for adjusting the supply amount of the second steam supplied from the second steam source, the header pressure detecting means for detecting the pressure of the pressure header, and the header pressure detecting means. A first steam instruction value for instructing the supply amount of the first steam, and a second steam instruction value for instructing the supply amount of the second steam, based on the applied pressure. Constant and, by the first steam indicated value and controls the first steam adjusting means, and a header pressure control means for controlling the second steam adjustment means by the second steam indicated value. The header pressure control means is provided in advance so that the minimum supply amount of the second steam is 0 or more, and based on the pressure detected by the header pressure detection means, the total supply of steam to the pressure header The total steam instruction value indicating the amount is calculated, and the calculated total steam instruction value is less than the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam. When it corresponds, the first steam instruction value and the second steam supply amount become the minimum supply amount, and the first steam supply amount becomes the supply amount according to the total steam instruction value and When a second steam instruction value is determined and the total steam instruction value is equal to or more than the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam, The first scan The first steam instruction value at which the supply amount of the steam is the maximum amount that can be supplied from the first steam source, and the second steam supply amount is determined to be the total steam instruction value and the first steam instruction value. A second steam instruction value corresponding to a difference from the maximum amount that can be supplied from one steam source is determined.

  In the pressure control method according to the present invention, the first steam from the first steam source and the second steam from the second steam source are supplied, and the first and second steams are used as the low pressure steam. A pressure header for storing the low-pressure steam to the outside, a first steam adjusting means for adjusting a supply amount of the first steam supplied from the first steam source, and a second steam source Based on the second steam adjusting means for adjusting the supply amount of the supplied second steam, the header pressure detecting means for detecting the pressure of the pressure header, and the pressure detected by the header pressure detecting means, A first steam instruction value for instructing the supply amount of one steam and a second steam instruction value for instructing the supply amount of the second steam are determined, and the first steam instruction value is used to determine the first steam instruction value. of A pressure control method in a low-pressure steam supply apparatus that controls a team adjustment unit and includes a header pressure control unit that controls the second steam adjustment unit according to the second steam instruction value. Based on the detected pressure, an all steam instruction value calculating step for calculating an all steam instruction value indicating the total supply amount of steam to the pressure header, and an all steam instruction value calculated by the all steam instruction value calculating step Comparing the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam provided in a range of 0 or more in advance, and the comparison step, The total steam indication value is less than the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam. When corresponding, the first steam instruction value and the second steam supply amount become the minimum supply amount, and the first steam supply amount becomes the supply amount according to the total steam instruction value. And determining the two steam instruction values and controlling the first steam source and the second steam source, and the comparing step, the all steam instruction values can be supplied from the first steam source. The first steam supply amount is the maximum amount that can be supplied from the first steam source when the total amount of the first steam is equal to or greater than the total amount of the second steam and the minimum supply amount of the second steam. The steam instruction value is determined, and the second steam supply value is determined according to the difference between the total steam instruction value and the maximum amount that can be supplied from the first steam source. And the first steel Controlling the source of the steam and the second steam source.

  According to the present invention, the first and second steam sources can be controlled with a simple configuration, the pressure in the pressure header can be kept constant, and steam can be stably supplied to steam-using equipment. it can.

  Hereinafter, a low-pressure steam supply apparatus to which the present invention is applied will be described in detail with reference to the drawings. FIG. 1 shows a configuration diagram of an embodiment of the present invention. The low-pressure steam supply apparatus 1 according to the present invention is supplied with the first steam S1 from the first steam source 11 and the steam S2 from the boiler 12, and supplies each supplied steam to a plurality of steam-using devices 2. Pressure header 13, first steam adjusting means 14 for adjusting the supply amount of first steam S1 supplied from first steam source 11, and boiler for adjusting the supply amount of steam S2 supplied from boiler 12 The adjustment means 15, the header pressure detection means 16 that detects the pressure of the pressure header 13, and the header pressure control means 17 that controls the first steam adjustment means 14 and the boiler adjustment means 15 are provided.

  The first steam source 11 in the low-pressure steam supply apparatus 1 is a generation source of steam generated in various plants, and is, for example, a large boiler. The first steam source 11 supplies the generated steam to the subsequent pressure header 13. At this time, the steam supplied from the first steam source 11 is referred to as a first steam S1 for explanation.

  A first steam adjusting means 14 for adjusting the supply amount of the first steam S1 is provided at the subsequent stage of the first steam source 11. The first steam adjusting means 14 is a steam control valve that adjusts the supply amount of the first steam S1. The first steam adjusting means 14 is connected to the header pressure control means 17, and the opening / closing amount of the valve is controlled by the header pressure control means 17.

  The boiler 12 is a boiler that is a second steam source in the low-pressure steam supply apparatus 1 and is a steam generation source similar to the first steam source 11. The boiler 12 supplies the generated steam to the subsequent pressure header 13. At this time, the steam supplied from the boiler 12 is referred to as steam S2 for explanation.

  In the fuel supply pipe to the boiler 12, boiler adjusting means 15 for adjusting the amount of steam generated by the boiler 12 and adjusting the amount of steam supplied from the boiler 12 is provided. The boiler adjusting means 15 is a valve that adjusts a fuel supply amount provided in a fuel supply pipe necessary for the operation of the boiler 12. The boiler adjusting means 15 adjusts the amount of steam generated by adjusting the amount of fuel supplied to the boiler 12 and adjusts the amount of steam supplied to the pressure header 13. The boiler adjusting means 15 is connected to the header pressure control means 17, and the opening / closing amount of the valve is controlled by the header pressure control means 17.

Note that the boiler adjusting means 15 does not completely stop the fuel supply but supplies the minimum amount of fuel that does not stop the operation of the boiler. In the boiler 12, the minimum generated steam S2 _min is generated by the minimum operation of the boiler. This minimum generated steam S2 _min is steam generated by maintaining the operating state of the boiler accompanying the supply of the minimum amount of fuel. By maintaining the operating state of the boiler, the time required for ignition and preheating of the boiler is reduced. It can be eliminated and responsiveness can be maintained. As described above, the boiler 12 is not limited to maintaining the minimum operation state, but may stop the fuel supply and completely stop the operation.

  The pressure header 13 is supplied with steam S1 and S2 from the first steam source 11 and the boiler 12, stores the supplied steam S1 and S2 as low-pressure steam, and supplies the steam to the plurality of steam-using devices 2 at the subsequent stage. The pressure header 13 is provided with header pressure detection means 16 for detecting the vapor pressure of the pressure header 13. The low-pressure steam referred to here refers to steam having a pressure lower than that of the first steam source 11 and the boiler 12 which are steam generation sources.

  The header pressure control means 17 is a control means for controlling the entire low pressure steam supply device 1 and is connected to the first steam adjustment means 14, boiler adjustment means 15, pressure header 13, header pressure detection means 16, and each device The detected value from is supplied, and a control signal is supplied to each device. Specifically, as shown in FIG. 2, the header pressure control unit 17 receives the header pressure value from the header pressure detection unit 16 and is set by the user from the target pressure setting unit 21. Is supplied, and a deviation calculation unit 22 for calculating a deviation between the set value and the header pressure value, and a deviation calculated by the deviation calculation unit 22 are input to calculate a total steam instruction value Mc. Unit 23, a steam supply balance determination unit 24 that generates a control signal for controlling the first steam adjustment means 14 and the boiler adjustment means 15 based on the total steam instruction value Mc, and the total steam based on the total steam instruction value Mc. The control parameter determination unit 25 determines a parameter for calculating the instruction value Mc.

  The target pressure setting unit 21 has an input unit (not shown), stores a set pressure value input by the user via the input unit, and outputs the set pressure value to the deviation calculation unit 22.

  The deviation calculation unit 22 calculates a deviation between the header pressure value from the header pressure detection unit 16 and the set pressure value from the target pressure setting unit 21, and outputs the deviation to the all steam instruction value calculation unit 23.

  The all steam instruction value calculation unit 23 receives the deviation from the deviation calculation unit 22 and calculates the total steam instruction value Mc indicating the total supply amount of steam by performing PID control calculation based on this value. All steam instruction values Mc are output to the steam supply balance determination unit 24.

  The steam supply balance determination unit 24 controls the control signal MV1 for controlling the first steam adjustment unit 14 and the boiler adjustment unit 15 based on the total steam instruction value Mc calculated by the all steam instruction value calculation unit 23. A signal MV2 is generated, and these control signals MV1 and MV2 are output to each device.

  The control parameter determination unit 25 stores a control parameter suitable for controlling the first steam adjustment unit 14 and a control parameter suitable for controlling the boiler adjustment unit 15. There is a mechanism for comparing the calculated total steam instruction value Mc with the total amount S of the maximum amount that can be supplied from the first steam source 11 and the minimum supply amount from the boiler 12, and the total steam instruction value Mc is the sum A control parameter suitable for controlling the first steam adjusting means 14 when the amount is less than the amount S, and a control parameter suitable for controlling the boiler adjusting means 15 when the total steam instruction value is equal to or greater than the total amount S. And output to all steam instruction value calculation unit 23. The control parameters stored in the control parameter determination unit 25 can be changed using input means (not shown).

  Next, an operation method of the low pressure steam supply apparatus 1 will be described.

  FIG. 3 shows the total steam instruction value Mc output from the header pressure control means 17 on the horizontal axis, and the steam S1 from the first steam source 11 supplied in accordance with the total steam instruction value Mc on the vertical axis. The first steam instruction value MV1 for instructing the steam and the second steam instruction value MV2 for instructing the steam S2 from the boiler 12 are shown.

As shown in FIG. 3, the first steam source 11 has a maximum steam S1 _max that is the maximum amount of steam S1 that can be supplied. Further, the boiler 12 is not completely stopped by the boiler adjusting means 15 but is supplied with the minimum amount of fuel capable of maintaining the minimum operation state and generating the minimum generated steam S2 _min. The amount is specified.

The header pressure control means 17 calculates the total steam instruction value Mc, which is the steam supply amount to the desired pressure header 13, and this total steam instruction value Mc is the minimum occurrence that is the maximum steam S1 _max and the minimum boiler supply amount. When the total amount of steam S2 _min is smaller, that is, when the steam supply amount to the pressure header 13 can be covered only by the minimum operation state of the boiler 12 and the first steam source 11, the boiler 12 The second steam instruction value MV2 of the supply amount of steam is set to the lowest generated steam S2 _min, and the first steam instruction value MV1 of the supply amount from the first steam source 11 is adjusted. The first steam instruction value MV1 and the second steam instruction value MV2 are determined according to the total steam instruction value Mc. However, at this time, the header pressure control means 17 controls the boiler adjusting means 15 so that the steam S2 becomes the lowest generated steam S2 _min for the boiler 12. Further, the steam S1 from the first steam source 11 is controlled to have an amount obtained by subtracting the second steam instruction value MV2 that is the minimum generated steam S2 _min from the total steam instruction value Mc.

Moreover, the header pressure control means 17 is only the minimum operation state of the boiler 12 and the 1st steam source 11 when the steam supply amount to the desired pressure header 13 is more than the maximum steam S1 _max. Thus, when the steam supply amount to the pressure header 13 cannot be covered, the first steam instruction value MV1 indicating the supply amount from the first steam source 11 becomes the maximum steam S1 _max. The boiler adjustment is performed so that the steam supply amount from the boiler 12 is adjusted according to the difference between the total steam instruction value Mc to the pressure header 13 and the value of the first steam instruction value MV1 as the maximum steam S1 _max. A second steam instruction value MV2 for controlling the means 15 is determined.

  FIG. 4 is a flowchart illustrating a pressure control method according to the present invention. In step S <b> 11, the header pressure control means 17 calculates the total steam instruction value Mc that indicates the total supply amount of steam to the pressure header 13 based on the pressure value detected by the header pressure detection means 16.

Next, in step S12, the header pressure control means 17 determines the calculated total steam instruction value Mc, the maximum steam S1 _max that indicates the maximum amount that can be supplied from the first steam source 11, and the minimum supply amount of the boiler 12. Is compared with the total amount of the minimum generated steam S2 _min . When the total steam instruction value Mc is less than the total amount, the process proceeds to step S13, and when it is equal to or greater than the total amount, the process proceeds to step S14.

Next, in step S13, the header pressure control means 17 indicates the total steam instruction value Mc that indicates the total supply amount of steam to the pressure header 13 calculated based on the header pressure value detected by the header pressure detection means 16. Is determined to be less than the total amount of the maximum steam S1 _max and the minimum generated steam S2 _min, and, as shown in FIG. 3, in the boiler 12, the boiler 12 is set to the minimum generated steam S2 _min. 12, the steam supply amount from the first steam source 11 is determined from the calculated total steam supply amount to the pressure header 13 and the minimum generated steam S2 _min. Is a value for controlling the first steam source 11 so as to be a value obtained by subtracting, and the first steam adjusting means 1 of the first steam source 11 4 and control signals MV1 and MV2 are output to the boiler adjusting means 15 of the boiler 12. That is, the control signal MV2 is S2 _min , and the control signal MV1 is (Mc−S2 _min ).

Next, in step S14, the header pressure control means 17 indicates the total steam instruction value Mc that indicates the total supply amount of steam to the pressure header 13 calculated based on the header pressure value detected by the header pressure detection means 16. Is determined to be equal to or greater than the total amount of the maximum steam S1 _max and the minimum generated steam S2 _min, and the total steam instruction value Mc becomes the maximum steam S1 _max in the first steam source 11 as shown in FIG. In this way, the boiler 12 controls the boiler 12 so that the maximum steam S1 _max is subtracted from the calculated total supply amount of steam to the pressure header 13. Control signals MV1, MV2 to the first steam adjusting means 14 of the first steam source 11 and the boiler adjusting means 15 of the boiler 12 Is output. That is, the control signal MV1 is S1 _max , and the control signal MV2 is (Mc−S1 _max ).

  In the low-pressure steam supply apparatus 1 having the above-described configuration, the header pressure control unit 17 determines the total steam instruction value Mc based on the header pressure value detected by the header pressure detection unit 16, and the first steam The adjusting means 14 and the boiler adjusting means 15 are controlled. The low-pressure steam supply apparatus 1 thus determines the first steam instruction value MV1 and the second steam instruction value MV2 instructing the steam supply amount from the boiler 12 based on the total steam instruction value Mc, The amount of steam supplied from one steam source 11 and the amount of steam supplied from the boiler 12 can be controlled. Further, the low-pressure steam supply apparatus 1 mainly uses the first steam source 11, and when the pressure in the pressure header 13 can be controlled only by the first steam source 11, such a case, when it cannot be controlled, Steam can be supplementarily supplied to the pressure header 13 using the boiler 12, and the inside of the pressure header 13 can be controlled to be a predetermined pressure. As described above, the low-pressure steam supply device 1 can control the first steam source 11 and the boiler 12 with a simple configuration, and can maintain the pressure in the pressure header 13 at a constant level. Steam can be supplied.

  Note that the low-pressure steam supply apparatus 1 is not limited to providing only the first steam source 11 and the boiler 12 as the steam generation source as described above, and may include, for example, a plurality of boilers 12.

It is a block diagram of a low-pressure steam supply device to which the present invention is applied. It is a block diagram of the header pressure control means of the low pressure steam supply apparatus to which this invention is applied. It is a correlation diagram of the control signal equivalent to the flow volume for controlling all the steam instruction values memorize | stored in the steam supply balance determination part, and each apparatus. It is a flowchart of the pressure control method to which this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Low pressure steam supply apparatus, 2 Steam use apparatus, 11 1st steam source, 12 Boiler, 13 Pressure header, 14 1st steam adjustment means, 15 Boiler adjustment means, 16 Header pressure detection means, 17 Header pressure control means, 21 target pressure setting unit, 22 deviation calculating unit, 23 all steam instruction value calculating unit, 24 steam supply balance determining unit, 25 control parameter determining unit

Claims (4)

A first steam from a first steam source and a second steam from a second steam source are supplied, the first and second steams are stored as low pressure steam, and the low pressure steam is supplied to the outside. A pressure header;
First steam adjusting means for adjusting a supply amount of the first steam supplied from the first steam source;
Second steam adjusting means for adjusting the supply amount of the second steam supplied from the second steam source;
Header pressure detecting means for detecting the pressure of the pressure header;
Based on the pressure detected by the header pressure detecting means, a first steam instruction value for instructing the supply amount of the first steam, and a second steam instruction value for instructing the supply amount of the second steam, Header pressure control means for controlling the first steam adjustment means according to the first steam instruction value, and controlling the second steam adjustment means according to the second steam instruction value,
The header pressure control means is
The minimum supply amount of the second steam is provided in advance in the range of 0 or more,
Based on the pressure detected by the header pressure detection means, a total steam instruction value indicating the total supply amount of steam to the pressure header is calculated, and the calculated total steam instruction value is the first steam source. If the total amount of the second steam is less than the total amount of the second steam and the minimum supply amount of the second steam, the supply amount of the second steam becomes the minimum supply amount, and the supply amount of the first steam Determine the first steam instruction value and the second steam instruction value so that the supply amount according to the total steam instruction value,
When the total steam indication value is equal to or greater than the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam, the supply amount of the first steam is The first steam instruction value that is the maximum amount that can be supplied from the first steam source is determined, and the supply amount of the second steam can be supplied from the entire steam instruction value and the first steam source. A low-pressure steam supply apparatus for determining a second steam instruction value according to a difference from a maximum amount. The header pressure control means is
When the calculated total steam instruction value is less than the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam, the supply amount of the first steam A first steam instruction value is determined by a PID calculation based on a preset PID parameter based on the relationship between the first steam instruction value and all steam instruction values;
When the calculated total steam instruction value is equal to or greater than the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam, the supply of the second steam The low-pressure steam supply apparatus according to claim 1, wherein the second steam instruction value is determined by PID calculation based on a preset PID parameter based on a relationship between the amount and the difference.   The low-pressure steam supply apparatus according to claim 1 or 2, wherein the second steam source is a steam boiler. A first steam from a first steam source and a second steam from a second steam source are supplied, the first and second steams are stored as low pressure steam, and the low pressure steam is supplied to the outside. A pressure header, a first steam adjusting means for adjusting a supply amount of the first steam supplied from the first steam source, and a supply amount of the second steam supplied from the second steam source. A second steam adjusting means for adjusting; a header pressure detecting means for detecting the pressure of the pressure header; and a first instruction for instructing the supply amount of the first steam based on the pressure detected by the header pressure detecting means. And a second steam instruction value for instructing the supply amount of the second steam, and controlling the first steam adjusting means according to the first steam instruction value. A pressure control method in the low-pressure steam supply system and a header pressure control means for controlling the steam adjustment means of the second by the second steam indicated value,
An all steam instruction value calculating step for calculating an all steam instruction value indicating the total amount of steam supplied to the pressure header based on the pressure detected by the header pressure detecting means;
The sum of all steam instruction values calculated in the all steam instruction value calculating step, the maximum amount that can be supplied from the first steam source, and the minimum supply amount of the second steam that is provided in a range of 0 or more in advance. A comparison step for comparing the quantity;
When the comparison step indicates that the total steam instruction value is less than the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam, The first steam instruction value and the second steam instruction value are determined so that the supply amount becomes the minimum supply amount, and the supply amount of the first steam becomes the supply amount according to the total steam instruction value, Controlling to control the first steam source and the second steam source;
When the comparison step indicates that the total steam indication value is equal to or greater than the total amount of the maximum amount that can be supplied from the first steam source and the minimum supply amount of the second steam, The first steam instruction value at which the supply amount is the maximum amount that can be supplied from the first steam source is determined, and the supply amount of the second steam is the total steam instruction value and the first steam value. Determining a second steam instruction value corresponding to a difference from a maximum amount that can be supplied from the source, and controlling the first steam source and the second steam source.

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