JPH0555762B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cooling water injection amount control device for a steam desuperheater, and in particular, it injects cooling water into superheated steam to control the temperature of the superheated steam to a predetermined temperature. The present invention relates to a cooling water injection amount control device for a steam desuperheater that reduces the amount of water to be injected.

[Prior Art] When using steam to superheat a substance, it is desirable to use saturated steam. FIG. 3 is a diagram showing a control system of a conventional cooling water injection amount control device for a steam desuperheater for converting superheated steam into saturated steam, and FIG. 4 is a steam state diagram.

In FIG. 3, superheated steam is supplied to a superheated steam pipe 1, and the steam pressure inside the superheated steam pipe 1 is detected by a pressure detector 2. The detection power of the pressure detector 2 is given to the steam pressure regulator 3, and the steam pressure regulator 3 adjusts the pressure to a preset steam pressure based on the steam pressure detected by the pressure detector 2. Control valve 4. Thereby, the pressure within the superheated steam pipe 1 is kept constant. The superheated steam pipe 1 is provided with a cooling water injection device 7 . A temperature detector 5 is provided on the exit side of the superheated steam pipe 1 to detect the temperature of the superheated steam. The temperature detected by this temperature detector 5 is provided to a steam temperature controller 6. The steam temperature controller 6 controls the flow rate of cooling water supplied to the cooling water injection device 7 so that the temperature detected by the temperature detector 5 becomes a preset temperature. Cooling is injected into the superheated steam by the cooling water injection device 7, and superheated steam whose temperature has been reduced is obtained at the outlet side of the superheated steam pipe 1. That is, the outlet side of the superheated steam pipe 1 is adjusted so that the steam temperature is constant.

[Problems to be solved by the invention] By the way, saturated steam has the following problems as shown in FIG.
Even if the temperature is constant, the degree of dryness varies depending on the amount of enthalpy. Therefore, as mentioned above, when detecting the temperature of superheated steam and controlling the injection amount of cooling water to maintain a constant temperature, if the flow rate of the steam used is not stable, the degree of superheating after temperature reduction will increase. It becomes difficult to reduce to 0. Generally, in a system using superheated steam, the flow rate of the steam changes from moment to moment, so in order to reduce the degree of superheat to 0 after cooling, the superheated steam is heated to a slightly higher degree of superheat. I was adjusting.

However, this adjustment was difficult and the object was unsuitable for use as heating steam.

Therefore, the main purpose of this invention is to inject cooling water that matches the flow rate of superheated steam from the respective enthalpies of superheated steam and cooling water, so that the steam after temperature reduction becomes dry and saturated steam, and is suitable for use as heating steam. An object of the present invention is to provide a cooling water injection amount control device for a steam desuperheater that can be processed into a steam desuperheater.

[Means for Solving the Problems] A cooling water injection amount control device for a steam desuperheater according to the present invention includes a temperature detection means for detecting the temperature of superheated steam, and a temperature detection means for detecting the flow rate of superheated steam. a steam flow rate detection means; a calculation control means for calculating an injection amount of cooling water to produce a preset dry saturated steam based on the detected temperature and flow rate; It consists of cooling water injection means that injects water into superheated steam.

[Operation] The cooling water injection amount control device for a steam desuperheater according to the present invention calculates the injection amount of cooling water to make dry saturated steam to a preset value based on the temperature of superheated steam and the steam flow rate. The amount of cooling water injected is then controlled based on the calculation results, making it possible to process superheated steam into dry saturated steam that is suitable as heating steam even in systems where the steam flow rate fluctuates widely. I can do it.

[Embodiment of the Invention] FIG. 1 is a schematic diagram showing a control system of an embodiment of the present invention, and FIG. 2 is a concrete block diagram of the cooling water flow rate setting device shown in FIG. 1.

First, the configuration of an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. In FIG. 1, the same superheated steam piping 1, pressure detector 2, steam pressure regulator 3, and pressure regulating valve 4 as shown in FIG. 3 are used. Further, the superheated steam pipe 1 is provided with a steam flow rate detector 8 that detects the flow rate of superheated steam in the superheated steam pipe 1, and a temperature detector 5 that detects the temperature of the superheated steam.
The flow rate detected by the steam flow rate detector 8 and the temperature detected by the temperature detector 5 are provided to a cooling water flow rate setting device 9. The cooling water flow rate setting device 9 calculates the cooling water flow rate corresponding to the steam flow rate based on the input flow rate and temperature, preset information and an arbitrary function, and adjusts the flow rate of the cooling water flow rate regulator 11. do. The cooling water flow rate regulator 11 is provided with a detection output from a water flow rate detector 10 that detects the flow rate of cooling water, and the flow rate detected by the water flow rate detector 10 is calculated by the cooling water flow rate setting device 9. The cooling water injection device 7 is controlled so that the flow rate becomes the same. Thereby, cooling water corresponding to the steam flow rate is injected from the cooling water injection device 7, processed into dry saturated steam, and output.

Next, the cooling water flow rate setting device 9 will be explained in detail. As shown in FIG. 2, the cooling water flow rate setting device 9 is composed of an input buffer 91, a constant setting device 92, a multiplexer 93, an A/D converter 94, a control section 95, an output circuit 96, and a display 97. . The input buffer 91 is supplied with the steam flow rate detected by the steam flow rate detector 8 shown in FIG. 1 described above and the steam temperature detected by the temperature detector 5. Note that the steam pressure detected by the pressure detector 2 is input to this input buffer 91, and
Alternatively, the temperature of the cooling water may be detected and the temperature information may be provided. The constant setter 92 is used to set the enthalpy of dry saturated steam to be obtained and the upper and lower limits of the amount of cooling water. Each piece of information input to the input buffer 91 and the set value set by the constant setter 92 are given to a multiplexer 93. The multiplexer 93 sequentially selects each piece of information given from the input buffer 91 and the set value set by the constant setter 92 and supplies them to the A/D converter 94 . A/D converter 94 converts the information into digital signals and provides them to control section 95.

The control unit 95 calculates the corrected steam flow rate and cooling water amount based on the input information. In other words, the steam pressure is P, the steam temperature is T, the differential pressure is Δp, the water injection temperature is Tw, and the corrected steam flow rate is
If Fs is the amount of cooling water and Fw is the amount of cooling water, then the corrected steam flow rate is
Fs is determined by the following formula.

However, K1 to K4 are constants. Also, the estimated cooling amount Fw is obtained by the following formula.

Fw=K5・T−K6・P−K7・P1+K8/K9・P1−K10・Tw+K
11 ・Fs/K12−K13・Tw However, K5 to K13 and P1 are constants Based on the corrected steam flow rate and cooling water amount calculated by the control unit 95 as described above, the output circuit 96 adjusts the cooling water flow rate. Set the amount of cooling water in the container 11. The cooling water flow rate regulator 11 controls the cooling water injection device 7 based on the amount of cooling water set by the cooling water flow rate setting device 9. Thereby, dry saturated steam is obtained from the output side of the superheated steam pipe 1.

[Effects of the Invention] As described above, according to the present invention, the injection amount of cooling water required to make superheated steam dry and saturated steam is calculated based on at least the flow rate and temperature of superheated steam, and The cooling water flow rate is adjusted using the setting value of the cooling water flow rate controller, and even in processes where the steam flow rate fluctuates greatly, superheated steam can be processed into dry saturated steam suitable as heating steam. I can do it. Therefore, it is possible to solve problems such as near-uniformity of heating surface dullness and generation of large thermal stress in a heating device using superheated steam.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a control system of an embodiment of the present invention. FIG. 2 is a concrete block diagram of the cooling water flow rate setting device shown in FIG. 1. FIG. 3 is a schematic diagram showing a control system of a conventional steam desuperheater cooling water injection amount control device. FIG. 4 is a state diagram of steam. In the figure, 1 is a superheated steam pipe, 2 is a pressure detector, 3 is a steam pressure regulator, 4 is a pressure regulating valve, 5 is a temperature detector, 7 is a cooling water injection device, 8 is a steam flow rate detector, and 9 is a steam flow rate detector. A cooling water flow rate setting device, 10 a water flow rate detector, and 11 a cooling water flow rate regulator.

Claims (1)

[Scope of Claims] 1. A cooling water injection amount control device for a steam desuperheater for controlling the injection amount of cooling water in order to convert superheated steam into dry saturated steam, the device comprising: detecting the temperature of the superheated steam; temperature detection means for detecting the flow rate of the superheated steam, steam flow rate detection means for detecting the flow rate of the superheated steam, based on the temperature detected by the temperature detection means and the flow rate detected by the steam flow rate detection means. , an arithmetic control means for calculating an injection amount of the cooling water in order to produce a preset dry saturated steam; and an arithmetic control means for injecting cooling water into the superheated steam based on the injection amount calculated by the arithmetic and control means. A cooling water injection amount control device for a steam desuperheater, which is equipped with a cooling water injection means. 2 further includes steam pressure detection means for detecting the pressure of the superheated steam, and the arithmetic control means is configured to detect the cooling temperature based on the pressure detected by the steam pressure detection means and the detected temperature and flow rate. A cooling water injection amount control device for a steam attemperator according to claim 1, which calculates an injection amount of water. 3. The cooling water injection means further includes a flow rate detection means for detecting the flow rate of the cooling water, and the cooling water injection means controls the overheating so that the flow rate detected by the flow rate detection means becomes the calculated injection amount. A cooling water injection amount control device for a steam desuperheater according to claim 1, which adjusts the flow rate of cooling water injected into the steam.