JP2011196604A - Diffusion valve control device and steam control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of drainage in steam piping and to stably supply steam by suppressing fluctuation of steam pressure even when the steam is diffused by opening a diffusion valve.SOLUTION: In a saturated steam temperature calculating section 11, the steam pressure Ps detected by a steam pressure detector 9 is input, and the steam pressure Ps is converted into a saturated steam temperature Tso of the steam in the steam piping 3, a steam temperature deviation calculating section 14 determines the steam temperature deviation ΔTs between the saturated steam temperature Tso determined by the saturated steam temperature calculating section 11 and the steam temperature in the steam piping detected by the steam temperature detector 10, and a steam temperature regulator 15 calculates opening command of the diffusion valve 6 so that the steam temperature in the steam piping 3 reaches the saturated steam temperature Tso or higher on the basis of the steam temperature deviation ΔTs determined by the steam temperature deviation calculating section 14, and outputs the opening command to the diffusion valve 6.

Description

  The present invention controls a diffusion valve that diffuses steam to the atmosphere in order to prevent the generation of drain in the steam piping of the steam supply system that supplies steam generated by the steam boiler to the user of the steam via the steam piping. The present invention relates to a diffusion valve control device and a steam control system.

  Generally, since the steam in the steam pipe is higher than the ambient temperature, the heat held by the steam is radiated to the atmosphere through the pipe outer wall. This heat loss may condense the vapor and generate drain. If this drain is present in the steam system, it will cause a decrease in thermal efficiency.In addition, the drain in the steam pipe will accumulate at the bottom of the pipe and will be pushed by the steam flowing at high speed, causing adverse effects such as promoting the generation of a water hammer. It has been known.

  For this reason, there is a system in which a drain recovery system that discharges drain generated in the steam pipe from the steam system is provided in the steam system (for example, see Patent Document 1). The thing of patent document 1 aims at the improvement of electric power generation efficiency not only collect | recovering drains by the drain tank in a power station but also effectively utilizing the heat which the collected drains hold.

  On the other hand, the supply of steam is controlled in consideration of the steam pressure and flow rate. For example, the reason why the steam pressure is controlled during the supply of steam is that if the steam pressure is too high, the equipment such as the steam piping will be adversely affected. For this reason, there is a steam pipe provided with a diffusion valve that diffuses the vapor to the atmosphere when the vapor pressure rises above an allowable pressure (see, for example, Patent Document 2). The thing of patent document 2 provides the diffusion valve in order to prevent the abnormal raise of a steam pressure in the main steam piping which sends the steam which generate | occur | produced with the exhaust heat recovery steam boiler of a gas turbine to a steam turbine.

  Moreover, there exists what provided the diffusion valve for the flow control of a vapor | steam (for example, refer patent document 3). The thing of patent document 3 is provided with a diffusion valve in the main steam piping which sends steam from the exhaust heat recovery steam boiler of a gas turbine to a steam turbine like the thing of patent document 2, and flows into a steam turbine by opening a diffusion valve suitably. The steam flow rate is controlled to adjust the output ratio between the gas turbine and the steam turbine.

JP 2009-8290 A (Claim 1 etc.) JP 2008-75996 A (Claim 1 etc.) JP 2007-92721 A (Claim 5 etc.)

  However, it is suitable to provide a drain tank and collect the drain as in Patent Document 1, when steam-related facilities such as in a power plant are relatively close to each other, but the steam generated in the steam boiler is widely used. When the steam supply business to supply to is performed, the supply route becomes long and the cost increases, which is not effective. In the steam supply business, the generation of drain means the loss of steam, so it is desirable to prevent the generation of drain in the first place.

  On the other hand, in Patent Document 2 and Patent Document 3, since the diffusion valve controls the pressure and flow rate of the steam and does not control the steam temperature, the generation of drain cannot be prevented beforehand. Furthermore, when steam is diffused by opening the radiation valve, the steam pressure temporarily fluctuates, which may impede steam supply.

  An object of the present invention is to provide a diffusion valve control device and a steam control system capable of preventing the generation of drain in the steam pipe and suppressing the fluctuation of the steam pressure even when the diffusion valve is opened to dissipate the steam and stably supplying the steam. Is to provide.

  According to a first aspect of the present invention, there is provided a diffusion valve control apparatus for preventing the generation of drain in the steam pipe of a steam supply system that supplies steam generated by a steam boiler to a steam usage destination via the steam pipe. In the diffusion valve control device that controls the opening degree of the diffusion valve provided in the steam pipe, the saturated steam temperature of the steam in the steam pipe is obtained based on the steam pressure in the steam pipe, and the steam temperature in the steam pipe A temperature control unit that calculates the opening command of the diffusion valve so that the temperature is equal to or higher than the saturated steam temperature, and the steam pressure in the steam pipe is set to be equal to or lower than a preset allowable pressure of the steam pressure in the steam pipe. An overpressure prevention unit that calculates an opening command of the diffusion valve, an opening command of the diffusion valve calculated by the temperature control unit, and an opening command of the diffusion valve calculated by the overpressure prevention unit Choose the larger one Characterized in that a maximum value selector for outputting the serial dissipation valve.

  According to a second aspect of the present invention, there is provided a diffusion valve control apparatus for preventing the generation of drain in the steam pipe of a steam supply system for supplying steam generated in a steam boiler to a steam usage destination via the steam pipe. In the diffusion valve control device that controls the opening degree of the diffusion valve provided in the steam pipe, the saturated steam temperature of the steam in the steam pipe is obtained based on the steam pressure in the steam pipe, and the steam temperature in the steam pipe A temperature control unit that calculates an opening command of the diffusion valve so that the temperature becomes equal to or higher than the saturated steam temperature, and a total steam flow to be supplied to the user uses a minimum steam flow rate for preventing drain generation in the steam pipe. A minimum flow rate control unit that calculates the opening command of the diffusion valve so as to maintain; an opening command of the diffusion valve calculated by the temperature control unit; and an opening command of the diffusion valve calculated by the minimum flow rate control unit When Out by selecting the larger is characterized in that a maximum value selector for outputting said dissipating valve.

  According to a third aspect of the present invention, there is provided a diffusion valve control apparatus for preventing the generation of drain in the steam pipe of a steam supply system for supplying steam generated in a steam boiler to a steam usage destination via the steam pipe. In the diffusion valve control device that controls the opening degree of the diffusion valve provided in the steam pipe, the saturated steam temperature of the steam in the steam pipe is obtained based on the steam pressure in the steam pipe, and the steam temperature in the steam pipe A temperature control unit that calculates the opening command of the diffusion valve so that the temperature is equal to or higher than the saturated steam temperature, and the steam pressure in the steam pipe is set to be equal to or lower than a preset allowable pressure of the steam pressure in the steam pipe. An overpressure prevention unit that calculates an opening command of the diffusion valve, and a total steam flow supplied to the user to maintain a minimum steam flow rate so as not to generate drain in the steam pipe. Opening A minimum flow rate control unit that calculates a command, an opening command of the diffusion valve calculated by the steam flow controller, an opening command of the diffusion valve calculated by the steam pressure controller, and a calculation by the steam temperature controller The maximum value selector which selects the largest thing among the opening degree instructions of the said diffusion valve, and outputs it to the said diffusion valve is provided.

  A diffusion valve control device according to a fourth aspect of the present invention is the diffusion valve control device according to any one of the first to third aspects, wherein the temperature control unit detects the vapor pressure detected by a vapor pressure detector that detects a vapor pressure in the vapor pipe. A saturated steam temperature calculation unit that converts the steam pressure into a saturated steam temperature of the steam in the steam pipe and outputs the saturated steam temperature, and a predetermined margin value for the saturated steam temperature obtained by the saturated steam temperature calculation unit And a steam management temperature calculation unit that calculates a steam management temperature, and a steam temperature detector that detects the steam management temperature obtained by the steam management temperature calculation unit and the steam temperature in the steam pipe. A steam temperature deviation calculating unit for obtaining a steam temperature deviation with respect to the steam temperature in the steam pipe, and the steam temperature in the steam pipe is equal to or higher than the saturated steam temperature based on the steam temperature deviation obtained by the steam temperature deviation calculating unit. Characterized in that a steam temperature controller the calculated opening command dissipation valve such that output to the dissipation valve.

  According to a fifth aspect of the present invention, there is provided the diffusion valve control device according to any one of the first to third aspects, wherein the excessive pressure prevention unit detects an allowable pressure of the steam pressure in the steam pipe and a steam pressure in the steam pipe. A steam pressure deviation computing unit for obtaining a steam pressure deviation with respect to the steam pressure detected by the steam pressure detector, and the steam pressure in the steam pipe based on the steam pressure deviation obtained by the steam pressure deviation computing unit The diffusion valve control device according to any one of claims 1 to 3, further comprising a steam pressure regulator that calculates an opening degree command of the diffusion valve so as to be equal to or lower than an allowable pressure.

  According to a sixth aspect of the present invention, there is provided the diffusion valve control device according to any one of the first to third aspects, wherein the minimum flow rate control unit supplies the minimum steam flow rate to prevent the drain from being generated in the steam pipe and the use destination. A steam flow deviation calculating unit for obtaining a steam flow deviation with respect to the total steam flow to be performed, and the steam flow in the steam pipe is maintained at the minimum steam flow based on the steam flow deviation obtained by the steam flow deviation calculating unit. A steam flow controller for calculating an opening command for the diffusion valve, an opening command for the diffusion valve calculated by the steam flow controller, and an opening command for the diffusion valve calculated by the steam temperature controller. The diffusion valve control device according to any one of claims 1 to 3, further comprising a maximum value selector that selects a larger one and outputs the highest value to the diffusion valve.

  According to a seventh aspect of the present invention, there is provided a diffusion valve control apparatus according to any one of the first to sixth aspects, wherein an adder that outputs the sum of the opening degree commands to the diffusion valve is provided instead of the maximum value selector. It is characterized by that.

  The steam control system according to the invention of claim 8 controls the opening degree of the diffusion valve control device according to any one of claims 1 to 7 and the steam supply valve provided in the steam pipe of the steam outlet of the steam boiler. A steam supply valve control device that detects the steam supply pressure at the outlet of the steam supply valve and detects the steam supply pressure detected by a steam supply pressure detector and a predetermined steam supply. A steam supply pressure deviation calculating unit for obtaining a steam supply pressure deviation with respect to the pressure setting value, a steam pressure fluctuation amount calculating unit for converting an opening degree command of the diffusion valve output from the diffusion valve control device into a steam pressure fluctuation amount, An adder for adding the steam pressure fluctuation amount obtained by the steam pressure fluctuation amount computing unit to the steam supply pressure deviation obtained by the steam supply pressure deviation computing unit; and an output value of the diffusion valve based on an output value from the adder. Due to opening change Characterized in that a steam supply pressure regulator that outputs the opening command of the steam supply valve in consideration of steam pressure variation amount in the steam supply valve.

  According to the diffusion valve control device of the present invention, in consideration of the steam temperature, the steam temperature in the steam pipe is set to be equal to or higher than the saturated steam temperature, and the steam pressure in the steam pipe is limited to a permissible pressure or less. Since the diffusion valve is controlled, it is possible to reliably prevent the generation of drain in the steam pipe while improving safety. Furthermore, even if the amount of steam used at the use site fluctuates, the steam flow rate in the steam pipe is maintained at the minimum steam flow rate that does not generate drain, so that it is possible to reliably prevent the drain from being generated in the steam pipe.

  In addition, according to the steam control system of the present invention, the steam supply valve is controlled in consideration of the steam pressure fluctuation amount due to the change in the opening degree of the diffusion valve. Therefore, even when the diffusion valve is opened to dissipate the steam, the steam pressure fluctuates. Steam can be supplied stably.

The steam supply system figure which shows an example of the steam supply system with which the diffusion valve control apparatus and steam control system concerning embodiment of this invention are applied. The block block diagram of Example 1 of the diffusion valve control apparatus concerning embodiment of this invention. The characteristic figure of an example of the function which converts the steam pressure Ps into the saturated steam temperature Tso in the saturated steam temperature calculating part in embodiment of this invention. The block block diagram of Example 2 of the diffusion valve control apparatus concerning embodiment of this invention. The block block diagram of Example 3 of the diffusion valve control apparatus concerning embodiment of this invention. The block block diagram of the steam control system concerning embodiment of this invention. The characteristic view of an example of the function which converts the opening degree of a diffusion valve into steam pressure fluctuation amount (DELTA) P in a steam pressure fluctuation amount calculating part.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the following embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified.

  FIG. 1 is a steam supply system diagram showing an example of a steam supply system to which a diffusion valve control device and a steam control system according to an embodiment of the present invention are applied. The steam supply system includes a steam boiler 1 that generates steam, a steam supply valve 2 that controls steam supply from the steam boiler 1, a steam pipe 3 that sends steam, and a plurality of users 4a that use the sent steam. To 4n, usage control valves 5a to 5n for controlling the supply of steam to the usages 4a to 4n, and a diffusion valve 6 for releasing the steam to the atmosphere. By appropriately dissipating the steam from the diffusion valve 6 to the atmosphere, a constant steam flow is secured in the steam pipe 3, and the generation of drain due to the stay of steam is prevented.

  The steam supply valve 2 is controlled by the steam supply valve control device 7, and the diffusion valve 6 is controlled by the diffusion valve control device 8. Further, FIG. 1 shows a case where the diffusion valve 6 is provided at the end portion of the steam pipe 3.

  The opening degree of the diffusion valve 6 provided at the end of the steam pipe 3 is controlled by the diffusion valve control device 8 so as to prevent the generation of drain in the steam pipe 3, and the boundary between the steam boiler 1 and the steam pipe 3 ( The opening degree of the steam supply valve 2 provided at the steam outlet of the steam boiler 1 is controlled by the steam supply valve control device 7. The diffusion valve control device 8 and the steam supply valve control device 7 constitute a steam control system.

  The flow of steam in such a steam supply system is as follows. The steam generated in the steam boiler 1 is sent to the steam pipe 3 after the steam pressure and the steam flow rate are adjusted by the steam supply valve 2 by the steam supply valve control device 7. Steam corresponding to the amount of use at the destinations 4a to 4n is sent from the steam pipe 3 through the destination control valves 5a to 5n. Further, in order to prevent the steam from staying in the steam pipe 3, the steam is appropriately diffused from the diffusion valve 6 to the atmosphere, and a constant flow of the steam is ensured.

  The steam boiler 1 may be of any type as long as a sufficient amount of steam can be generated in the steam boiler 1. For example, not only a coal steam boiler and a heavy oil steam boiler that generate fuel by burning fuel, but also an exhaust heat recovery steam boiler that introduces exhaust gas from a gas turbine and generates steam by its exhaust heat, and the like.

  The usage destinations 4a to 4n widely include facilities and facilities that can use steam as a heat source such as factories and buildings. As long as the steam can be supplied by the steam pipe 3, the steam boiler 1 and the users 4a to 4n are not separated from each other. However, as will be described later, the diffusion valve control device according to the embodiment of the present invention is particularly used. It is suitably used for a steam supply system in which 4a to 4n are dispersed over a wide range.

  FIG. 2 is a block configuration diagram of Example 1 of the diffusion valve control device according to the embodiment of the present invention. The diffusion valve control device 8 includes a temperature control unit 18, an excessive pressure prevention unit 16, and a maximum value selector 17. The temperature control unit 18 calculates the opening degree command s1 of the diffusion valve 6 so that the steam temperature Ts in the steam pipe 3 is equal to or higher than the saturated steam temperature Tso, and outputs it to the maximum value selector 17. The excessive pressure prevention unit 19 calculates the opening degree command s2 of the diffusion valve 6 so that the steam pressure Ps in the steam pipe 3 becomes equal to or lower than the preset allowable pressure Pm in the steam pipe 3, and a maximum value selector 17 is output. The maximum value selector 17 selects the larger one of the opening command s1 of the diffusion valve 6 calculated by the temperature control unit 18 and the opening command s2 of the diffusion valve 6 calculated by the excessive pressure prevention unit 16 to select the diffusion valve. 6 is output as an opening degree command s, and the release valve 6 is controlled to open and close.

  The temperature control unit 18 inputs the steam pressure Ps in the steam pipe 3 detected by the steam pressure detector 9 and the steam temperature Ts detected by the steam temperature detector 10. The steam pressure Ps detected by the steam pressure detector 9 is input to the saturated steam temperature calculation unit 11 of the temperature control unit 18 and converted to the saturated steam temperature Tso by the saturated steam temperature calculation unit 11. FIG. 3 is a characteristic diagram of an example of a function for converting the steam pressure Ps into the saturated steam temperature Tso by the saturated steam temperature calculation unit 11. As shown in FIG. 3, the saturated steam temperature Ts is expressed as a function of the steam pressure Ps, and has a characteristic that the saturated steam temperature Ts increases as the steam pressure Ps increases. The saturated steam temperature calculation unit 11 converts the steam pressure Ps into the saturated steam temperature Tso based on the function shown in FIG.

  Next, the saturated steam temperature Tso obtained by the saturated steam temperature calculation unit 11 is input to the adder 12, and a preset margin value α is added to the margin value setter 13, so that the management temperature Tsr (= Tso + α) is obtained. Desired. Since the management temperature Tsr is a target value of the steam temperature Ts, a value obtained by adding a margin value α to the saturated steam temperature Tso so that drain does not occur in the steam pipe 3. The management temperature Tsr obtained by the adder 12 is input to the steam temperature deviation calculator 14.

  The steam temperature deviation calculating unit 14 receives the management temperature Tsr from the adder 12 and the steam temperature Ts detected by the steam temperature detector 10 and obtains the steam temperature deviation ΔTs (= Tsr−Ts). The steam temperature deviation ΔTs obtained by the steam temperature deviation calculator 14 is input to the steam temperature controller 15, and the steam temperature controller 15 sets the opening command s 1 of the diffusion valve 6 so that the steam temperature deviation ΔTs becomes zero. Calculate and output to the diffusion valve 6. Thereby, the steam temperature Ts in the steam pipe 3 is controlled to be equal to or higher than the saturated steam temperature Tso.

  Here, since the drain is generated when the steam temperature Ts in the steam pipe 3 is lower than the saturated steam temperature Tso, the diffusion valve control device 8 of the first embodiment causes the steam temperature Ts to be equal to or higher than the saturated steam temperature Tso. In addition, the opening degree of the diffusion valve 6 is controlled.

  Therefore, the margin value α is determined so that the steam temperature Ts in the steam pipe 3 becomes equal to or higher than the saturated steam temperature Tso, but generally the margin value α is set to a value in the range of several percent of the saturated steam temperature Tso. It is preferable to do this. If the margin value α is smaller than this range, the control becomes sweet and there is a high possibility that drain is generated. Conversely, if the margin value α is large, the control becomes too strict and the steam diffused from the diffusion valve 6 increases and the loss increases.

  When the steam temperature Ts in the steam pipe 3 falls below the control value Tsr (saturated steam temperature Tso + α), the release valve 6 is opened and the steam whose temperature is lowered is released into the atmosphere, and fresher steam is introduced. By doing so, the steam temperature Ts in the steam pipe 3 is raised to the saturated steam temperature Tso or more, and the generation of drain is prevented.

  Next, the excessive pressure prevention unit 16 includes an allowable pressure setting device 19 in which the allowable pressure Pm of the steam pressure Ps in the steam pipe 3 is set, and the allowable pressure Pm set in the allowable pressure setting device 19 and the inside of the steam piping 3. The steam pressure deviation calculating unit 20 for determining the steam pressure deviation ΔPs (= Ps−Pm) with the steam pressure Ps detected by the steam pressure detector 9 for detecting the steam pressure Ps of The steam pressure controller 21 calculates an opening degree command of the diffusion valve 6 so that the steam pressure Ps in the steam pipe 3 becomes equal to or less than the allowable pressure Pm based on the steam pressure deviation ΔPs.

  The steam pressure Ps detected by the steam pressure detector 9 is input to the steam pressure deviation calculation unit 20 of the excessive pressure prevention unit 16, and the steam pressure deviation ΔPs from the allowable pressure Pm set in the allowable pressure setting unit 19 (= Ps−Pm) is calculated. The steam pressure deviation ΔPs obtained by the steam pressure deviation computing unit 20 is input to the steam pressure regulator 21, and the steam pressure regulator 21 computes the opening command s2 of the diffusion valve 6 so that the steam pressure deviation ΔPs becomes zero. To do. That is, when the steam flow rate in the steam pipe 3 decreases, the steam pressure Ps in the steam pipe 3 increases, so that the opening command of the diffusion valve 6 is calculated so that the steam pressure Ps does not exceed the allowable pressure Pm.

  Then, the steam pressure regulator 21 is output to the maximum value selector 17. The maximum value selector 17 is also input with the opening command s1 of the diffusion valve 6 from the steam temperature controller 15 of the temperature controller 18, and the maximum value selector 17 is the steam temperature controller 15 of the temperature controller 18. The larger one of the opening command s <b> 1 of the diffusion valve 6 from and the opening command s <b> 2 of the diffusion valve 6 from the steam pressure regulator 21 of the excessive pressure prevention unit 16 is selected and output to the diffusion valve 6.

  In the state where the opening degree of the diffusion valve 6 is controlled by the opening degree command s1 of the diffusion valve 6 from the steam temperature controller 15 of the temperature control unit 18, the diffusion valve from the steam pressure controller 21 of the excessive pressure prevention unit 16 When the opening degree command s2 of 6 is increased, the opening degree of the diffusion valve 6 is opened to a greater extent. Therefore, the steam whose temperature has been lowered is diffused from the diffusion valve 6 to the atmosphere and fresh steam flows into the atmosphere. I will let you. Therefore, no drain is generated in the steam pipe 3, and the steam pressure Ps can be limited to the allowable pressure Pm or less.

  On the other hand, in the state in which the opening degree of the diffusion valve 6 is controlled by the opening degree command of the diffusion valve 6 from the steam pressure regulator 21 of the excessive pressure prevention unit 16, the diffusion from the steam temperature regulator 15 of the temperature control unit 18. Even when the opening degree command s1 of the valve 6 becomes large, the opening degree of the diffusion valve 6 becomes a direction in which the opening degree becomes larger, so that the steam pressure Ps does not become larger than the allowable pressure Pm, There is no drainage.

  Various existing pressure gauges can be used for the steam pressure detector 9 that detects the steam pressure Ps in the steam pipe 3, and similarly, various existing thermometers can be used for the steam temperature detector 10. .

  The installation position of the steam pressure detector 9 and the steam temperature detector 10 may be any position within the steam pipe 3, but is preferably near the end of the steam pipe 3 close to the diffusion valve 6. This is because the vicinity of the end of the steam pipe 3 is an area where the steam temperature Ts is the lowest in the steam pipe 3 and drainage is likely to occur. Therefore, the opening of the diffusion valve 6 is controlled based on the steam temperature Ts in this area. This is because the generation of drain can be effectively prevented.

  According to Example 1 in the embodiment of the present invention, the opening degree of the diffusion valve 6 is controlled so that the steam temperature Ts in the steam pipe 3 becomes equal to or higher than the saturated steam temperature Tso. It can be surely prevented from occurring. Moreover, since the steam pressure Ps in the steam pipe 3 can be limited to the allowable pressure Pm or less, safety can be further improved.

  Next, Example 2 of the diffusion valve control apparatus according to the embodiment of the present invention will be described. FIG. 4 is a block configuration diagram of Example 2 of the diffusion valve control device according to the embodiment of the present invention. The second embodiment is different from the first embodiment shown in FIG. 2 in that a minimum flow rate control unit 22 is provided in place of the excessive pressure prevention unit 16.

  The minimum flow rate control unit 22 has a diffusion valve 6 so that the steam flow rate in the steam pipe 3 can ensure the minimum steam flow rate Qs that does not generate drain in the steam pipe 3 even if the amount of steam used at the destinations 4a to 4n varies. Is to control. The same elements as those in FIG.

  The minimum flow rate control unit 22 includes a minimum steam flow rate setting unit 24 in which a minimum steam flow rate Qs is set so as not to generate drain in the steam pipe 3, and a minimum steam flow rate Qs and steam set in the minimum steam flow rate setting unit 24. A steam flow deviation calculation unit 25 for obtaining a steam flow deviation ΔQs (= Qs−Qt) with a total steam flow Qt supplied from the boiler 1 to the users 4a to 4n, and a steam flow deviation ΔQs obtained by the steam flow deviation calculation unit 25 And a steam flow rate regulator 26 for calculating the opening degree command s3 of the diffusion valve 6 so that the steam flow rate in the steam pipe 3 maintains the minimum steam flow rate Qs.

  When the total steam flow Qt supplied from the steam boiler 1 to the users 4a to 4n is larger than the minimum steam flow Qs set in the minimum steam flow setter 24, the steam flow in the steam pipe 3 is maintained at the minimum steam flow Qs. it can. From this, the steam flow deviation calculator 25 obtains a steam flow deviation ΔQs (= Qs−Qt) between the minimum steam flow Qs and the total steam flow Qt supplied to the users 4a to 4n, and the steam flow controller 26 Based on this steam flow deviation ΔQs (= Qs−Qt), the opening degree command s3 of the diffusion valve 6 is calculated.

  That is, when the total steam flow Qt supplied to the users 4a to 4n is larger than the minimum steam flow Qs, the steam flow deviation ΔQs (= Qs−Qt) becomes a negative value. Is calculated as the opening degree command s3 in the direction of closing. On the other hand, when the total steam flow Qt supplied to the users 4a to 4n is smaller than the minimum steam flow Qs, the steam flow deviation ΔQs (= Qs−Qt) becomes a positive value. Is calculated as an opening degree command s3 in the direction of opening the.

  The maximum value selector 17 is an opening command s3 of the diffusion valve 6 calculated by the steam flow controller 26 of the minimum flow controller 22, and an opening command of the diffusion valve 6 calculated by the steam temperature controller 15 of the temperature controller 18. A larger one of s1 is selected and output as an opening degree command s to the diffusion valve 6. Thereby, even if the amount of steam used at the destinations 4a to 4n varies, the minimum steam flow rate Qs at which the steam flow rate in the steam pipe 3 does not generate drain in the steam pipe 3 can be secured.

  According to Example 2 in the embodiment of the present invention, the minimum steam that does not generate drainage in the steam flow rate in the steam pipe 3 even if the use steam amount of the use destinations 4a to 4n fluctuates by the minimum flow rate control unit 22. Since the flow rate is maintained at Qs, the generation of drain in the steam pipe 3 can be reliably prevented.

  Next, Example 3 of the diffusion valve control apparatus according to the embodiment of the present invention will be described. FIG. 5 is a block configuration diagram of Example 3 of the diffusion valve control apparatus according to the embodiment of the present invention. In the third embodiment, the minimum flow rate control unit 22 shown in the second embodiment shown in FIG. 4 is added to the first embodiment shown in FIG.

  In the third embodiment, the maximum value selector 17 is calculated by the opening command s3 of the diffusion valve 6 calculated by the steam flow controller 26 of the minimum flow controller 22 and the steam pressure controller 21 of the excessive pressure prevention unit 16. The opening command s2 for the diffusion valve 6 is selected from the opening command s2 for the diffusion valve 6 and the opening command s1 for the diffusion valve 6 calculated by the steam temperature controller 15 of the temperature control unit 18, and the opening command s for the diffusion valve 6 is selected. Output as.

  Thereby, in addition to the effects of the first embodiment, it is possible to secure the minimum steam flow rate Qs at which the steam flow rate in the steam pipe 3 does not generate drain in the steam pipe 3 even if the steam usage amount of the use destinations 4a to 4n varies.

  In the above description, the case where the maximum value selector 17 is provided has been described, but an adder may be provided instead of the maximum value selector 17. In the case of the first embodiment, the opening command s2 of the diffusion valve 6 calculated by the steam pressure controller 21 of the excessive pressure prevention unit 16 and the opening of the diffusion valve 6 calculated by the steam temperature controller 15 of the temperature control unit 18. The sum with the command s 1 is obtained by an adder, and the sum is output as the opening command s to the diffusion valve 6. Similarly, in the case of the second embodiment, the opening command s3 of the diffusion valve 6 calculated by the steam flow controller 26 of the minimum flow control unit 22 and the opening of the diffusion valve 6 calculated by the steam temperature controller 15 of the temperature control unit 18 are used. The sum with the degree command s 1 is obtained by an adder, and the sum is output as the opening degree command s to the diffusion valve 6.

  Furthermore, in the case of the third embodiment, the opening command s3 of the diffusion valve 6 calculated by the steam flow controller 26 of the minimum flow controller 22 and the diffusion valve calculated by the steam pressure controller 21 of the excessive pressure prevention unit 16 are used. 6 is obtained by an adder, and the sum of the opening command s2 of the diffusion valve 6 calculated by the steam temperature controller 15 of the temperature control unit 18 is obtained. Output as. By obtaining the sum of the respective opening commands, the opening of the diffusion valve 6 is increased, but the certainty of multifaceted control regarding the flow rate, pressure, and temperature of the steam can be further increased.

  Next, the steam control system according to the embodiment of the present invention will be described. FIG. 6 is a block diagram of a steam control system according to the embodiment of the present invention. The steam control system according to this embodiment includes a diffusion valve control device 8 according to Examples 1 to 3 and a steam supply valve control device that controls the opening degree of the steam supply valve 2 in accordance with the opening degree of the diffusion valve 6. 7.

  The steam supply valve control device 7 inputs the steam supply pressure Pks detected by the steam supply pressure detector 27 at the outlet of the steam supply valve 2 and the opening degree of the diffusion valve 6, and steam due to the change in the opening degree of the diffusion valve 6. The steam supply valve 2 is controlled in consideration of the pressure fluctuation amount.

  A predetermined steam supply pressure set value Pko is set in the steam supply pressure setting unit 28 of the steam supply valve control device 7. The steam supply pressure deviation calculating unit 29 obtains a steam supply pressure deviation ΔPk between the steam supply pressure Pks detected by the steam supply pressure detector 27 and a predetermined steam supply pressure set value Pko, and outputs it to the adder 30. .

  On the other hand, the steam pressure fluctuation calculation unit 31 of the steam supply valve control device 7 is input with the opening command s (opening of the diffusion valve 6) of the diffusion valve 6 output from the diffusion valve control device 8, and the steam pressure. The fluctuation amount calculation unit 31 converts the opening degree of the diffusion valve 6 into a steam pressure fluctuation amount ΔP and outputs it to the adder 30.

  FIG. 7 is a characteristic diagram of an example of a function for converting the opening degree of the diffusion valve 6 into the steam pressure fluctuation amount ΔP by the steam pressure fluctuation amount calculation unit 31. As shown in FIG. 7, the steam pressure fluctuation amount ΔP is expressed as a function of the opening degree of the diffusion valve 6, and has a characteristic that the steam pressure fluctuation quantity ΔP increases as the opening degree of the diffusion valve 6 increases. This function is set so as to satisfy the relationship between the steam pressure fluctuation amount ΔP in the steam supply valve 2 and the opening degree of the diffusion valve 6. For example, assuming that the influence of steady pressure fluctuation is larger when the opening degree of the diffusion valve 6 is small, the steam pressure fluctuation amount ΔP in the steam supply valve 2 is set to be small, and when the opening degree of the diffusion valve 6 increases, the radiation is dissipated. Assuming that the opening degree of the valve 6 has a great influence, the steam pressure fluctuation amount ΔP is set to increase exponentially.

  Further, since it is preferable to output the steam pressure fluctuation amount ΔP in consideration of the separation between the diffusion valve 6 and the steam supply valve 2, for example, the delay time of the steam pressure fluctuation is calculated in consideration of the separation, and the steam supply valve This is reflected in the control of the opening degree of 2.

  Next, the adder 30 adds the steam pressure fluctuation amount ΔP obtained by the steam pressure fluctuation amount calculation unit 31 to the steam supply pressure deviation ΔPk obtained by the steam supply pressure deviation calculation unit 29, and the steam supply pressure regulator 32. Output to. The steam supply pressure controller 32 outputs an opening degree command for the steam supply valve 2 to the steam supply valve 2 based on the output value (ΔPk + ΔP) from the adder 30. Thereby, since the steam pressure fluctuation amount ΔP due to the change in the opening degree of the diffusion valve 6 is included in the opening degree command of the steam supply valve 2, the steam supply valve is taken into consideration by the steam pressure fluctuation amount ΔP due to the opening degree change of the diffusion valve 6. 2 can be controlled.

  According to the steam supply system according to the embodiment of the present invention, even when the diffusion valve 6 is opened to dissipate the steam, the steam supply pressure Pks does not fluctuate and the steam can be stably supplied.

DESCRIPTION OF SYMBOLS 1 ... Steam boiler, 2 ... Steam supply valve, 3 ... Steam piping, 4 ... Usage destination, 5 ... Usage destination control valve, 6 ... Dissipation valve, 7 ... Steam supply valve control apparatus, 8 ... Dissipation valve control apparatus, 9 ... Steam pressure detector, 10 ... Steam temperature detector, 11 ... Saturated steam temperature calculator, 12 ... Adder, 13 ... Margin value setter, 14 ... Steam temperature deviation calculator, 15 ... Steam temperature controller, 16 ... Excessive Pressure prevention unit, 17 ... Maximum value selector, 18 ... Temperature control unit, 19 ... Allowable pressure setter, 20 ... Steam pressure deviation calculation unit, 21 ... Steam pressure controller, 22 ... Minimum flow rate control unit, 24 ... Minimum steam Flow rate setting unit, 25 ... Steam flow rate deviation calculating unit, 26 ... Steam flow rate controller, 27 ... Steam supply pressure detector, 28 ... Steam supply pressure setting unit, 29 ... Steam supply pressure deviation calculating unit, 30 ... Adder, 31 ... Steam pressure fluctuation calculation unit, 32 ... Steam supply pressure controller

Claims (8)

  Controls the opening degree of the diffusion valve provided in the steam pipe to prevent the generation of drain in the steam pipe of the steam supply system that supplies the steam generated from the steam boiler to the steam user through the steam pipe In the diffusion valve control device, the saturation valve temperature of the steam in the steam pipe is obtained based on the steam pressure in the steam pipe so that the steam temperature in the steam pipe becomes equal to or higher than the saturated steam temperature. A temperature control unit that calculates the opening command of the steam valve, and an excessive pressure that calculates the opening command of the diffusion valve so that the steam pressure in the steam pipe is equal to or lower than a preset allowable pressure of the steam pressure in the steam pipe A maximum of the prevention valve, the opening command of the diffusion valve calculated by the temperature control unit, and the opening command of the diffusion valve calculated by the excessive pressure prevention unit, and output to the diffusion valve With a value selector Dissipating valve control device, characterized in that.   Controls the opening degree of the diffusion valve provided in the steam pipe to prevent the generation of drain in the steam pipe of the steam supply system that supplies the steam generated from the steam boiler to the steam user through the steam pipe In the diffusion valve control device, the saturation valve temperature of the steam in the steam pipe is obtained based on the steam pressure in the steam pipe so that the steam temperature in the steam pipe becomes equal to or higher than the saturated steam temperature. A temperature control unit that calculates the opening command of the exhaust valve, and calculates the opening command of the diffusion valve so that the total steam flow supplied to the user maintains a minimum steam flow so as not to generate drain in the steam pipe And selecting the larger one of the opening command of the diffusion valve calculated by the temperature control unit and the opening command of the diffusion valve calculated by the minimum flow control unit to the diffusion valve output Dissipating valve controller is characterized in that a maximum value selector that.   Controls the opening degree of the diffusion valve provided in the steam pipe to prevent the generation of drain in the steam pipe of the steam supply system that supplies the steam generated from the steam boiler to the steam user through the steam pipe In the diffusion valve control device, the saturation valve temperature of the steam in the steam pipe is obtained based on the steam pressure in the steam pipe so that the steam temperature in the steam pipe becomes equal to or higher than the saturated steam temperature. A temperature control unit that calculates the opening command of the steam valve, and an excessive pressure that calculates the opening command of the diffusion valve so that the steam pressure in the steam pipe is equal to or lower than a preset allowable pressure of the steam pressure in the steam pipe A minimum flow rate control unit that calculates an opening degree command of the diffusion valve so as to maintain a minimum steam flow rate so that a total steam flow rate supplied to the user does not generate drain in the steam pipe, Of the opening command of the diffusion valve calculated by the air flow controller, the opening command of the diffusion valve calculated by the steam pressure controller, and the opening command of the diffusion valve calculated by the steam temperature controller A diffusion valve control device comprising a maximum value selector that selects a large value and outputs the selected value to the diffusion valve.   The temperature control unit inputs the steam pressure detected by a steam pressure detector that detects the steam pressure in the steam pipe, converts the steam pressure into a saturated steam temperature of the steam in the steam pipe, and outputs it. Saturated steam temperature calculation unit, a steam management temperature calculation unit that calculates a steam management temperature by adding a predetermined margin value to the saturated steam temperature obtained by the saturated steam temperature calculation unit, and the steam management temperature calculation unit A steam temperature deviation calculating unit for obtaining a steam temperature deviation between the steam management temperature obtained in step 1 and a steam temperature in the steam pipe detected by a steam temperature detector for detecting a steam temperature in the steam pipe; Steam temperature adjustment for calculating an opening degree command of the diffusion valve and outputting it to the diffusion valve so that the steam temperature in the steam pipe is equal to or higher than the saturated steam temperature based on the steam temperature deviation obtained by the temperature deviation calculation unit vessel Dissipating valve control device according to any one of claims 1 to 3, further comprising a.   The excessive pressure prevention unit calculates a steam pressure deviation between a permissible pressure of the steam pressure in the steam pipe and a steam pressure deviation detected by a steam pressure detector that detects the steam pressure in the steam pipe. And a steam pressure regulator that calculates an opening command of the diffusion valve based on the steam pressure deviation obtained by the steam pressure deviation calculating unit so that the steam pressure in the steam pipe is equal to or lower than the allowable pressure. The diffusion valve control device according to any one of claims 1 to 3, further comprising:   The minimum flow rate control unit includes a steam flow rate deviation calculating unit for obtaining a steam flow rate deviation between a minimum steam flow rate for preventing drain generation in the steam pipe and a total steam flow rate supplied to the user, and the steam flow rate deviation calculation A steam flow controller for calculating an opening degree command of the diffusion valve so that the steam flow in the steam pipe maintains the minimum steam flow based on the steam flow deviation obtained in the unit, and the steam flow controller A maximum value selector that selects the larger one of the opening command of the diffusion valve and the opening command of the diffusion valve calculated by the steam temperature controller and outputs the selected one to the diffusion valve. The diffusion valve control device according to any one of claims 1 to 3. 7. The diffusion valve control device according to claim 1, further comprising an adder that outputs a sum of the opening degree commands to the diffusion valve, instead of the maximum value selector. The diffusion valve control device according to any one of claims 1 to 7, and a steam supply valve control device that controls an opening degree of a steam supply valve provided in the steam pipe at a steam outlet of the steam boiler. The supply valve control device determines a steam supply pressure deviation between the steam supply pressure detected by a steam supply pressure detector that detects a steam supply pressure at the outlet of the steam supply valve and a predetermined steam supply pressure set value. A supply pressure deviation calculation unit, a steam pressure fluctuation amount calculation unit that converts the opening degree command of the diffusion valve output from the diffusion valve control device into a steam pressure fluctuation amount, and the steam supply obtained by the steam supply pressure deviation calculation unit An adder that adds the steam pressure fluctuation amount obtained by the steam pressure fluctuation amount calculation unit to the pressure deviation, and the steam pressure fluctuation amount due to a change in the opening of the diffusion valve based on the output value from the adder Steam supply valve Vapor control system is characterized in that a steam supply pressure regulator for outputting a degree command to the steam supply valve.

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