JPH0454511A - Highly accurate flow rate control system for plural nozzle groups - Google Patents

Abstract

PURPOSE:To improve the setting accuracy of a flow rate, to facilitate the adjustment and to decrease the number of control loops for flow rate control by arranging plural flow rate control blocks which can be set to each prescribed throttling value in parallel with each other at the throttling mechanism of the draining side and switching freely a 3-way valve. CONSTITUTION:The water is sprayed to the steel stock carried in an attitude H through the multi-stage nozzle groups 13. Thus a flange is cooled. The stages of the groups 13 are selected by opening/closing a valve 7 in accordance with the width of the flange 14. Then plural control blocks are provided in order to satisfy the steel stock cooling conditions, and a cooling pattern is changed by switching a 3-way valve to the nozzle or draining side. The opening amount of an opening amount control valve 8 is obtained at every control block by reference to a computer table when the valve 7 is set. Then the opening amount of the valve 8 is set at the value set with coincidence secured between the pipeline resistance coefficients of the 3-way valve obtained at the nozzle and detaining sides respectively. Thus the flow rate can be easily adjusted, and the highly accurate control of the flow rate is attained together with the complicated switch of the 3-way valve.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is aimed at suppressing flow rate fluctuations when switching valves as much as possible in piping equipment that uses nozzles for purposes such as cooling, and by changing the number of nozzles. This invention relates to a piping system control system that has a function to change the set.

The details will be described later in the examples, but the nozzle group is divided into stages according to the manufacturing size, and each three-way valve has a piping system consisting of multiple control blocks, allowing for strict flow control and frequent three-way valve switching. It can be applied to flange water cooling equipment for H-beam steel.

[Prior Art] In liquid piping equipment, it is common to use a three-way valve as shown in FIG. 8 as a method of minimizing flow rate fluctuations due to valve switching. In the figure, 1 is a three-way valve;
2 indicates the water supply side, 3 indicates the nozzle side, and 4 indicates the drainage side. The principle of a three-way valve is that when the nozzle on the downstream side of the water supply side 2 is not in use, the fluid flows to the drain side 4, and when the valve is switched, the flow rate fluctuation is minimized by not changing the flow of the upstream fluid. It is.

In a flow control system that performs strict flow control, in order to ensure the set flow rate conditions and minimize flow fluctuations when switching valves, a three-way valve is used, and the nozzle side and drainage It is necessary to equalize the pressure loss on both sides. For this reason, conventionally, the pipe pressure loss on the nozzle side is measured, a pressure loss corresponding to the pressure loss is calculated or measured on the drainage side, and a fixed pressure loss restricting mechanism 5 such as an orifice is inserted.

[Problem to be solved by the invention] Assuming the use explained in the section of the industrial application field above, the permissible range of adaptation of the above-mentioned conventional technology in terms of accuracy is very narrow for the following reasons. Limited to a range.

That is, FIG. 9 shows details of the three-way valve nozzle side 3 of the piping system in which the number of nozzles used on the downstream side of the three-way valve is changed according to manufacturing conditions. In the figure, 6 indicates a multi-stage nozzle, and 7 indicates an opening/closing valve for each nozzle 6.

For example, by opening and closing the on-off valve 7 in accordance with the size of the material to be cooled, the pressure drop on the nozzle side will naturally change as the number of nozzles used changes. It cannot be controlled.

Although it is possible to have a three-way valve instead of the on-off valve 7, the number of three-way valves or the number of on-off valves requires synchronization of their switching timings. Generally, switching timing adjustment involves adjusting the deviation of the three-way valve switching signal, adjusting the variation in the mechanical operation time of the three-way valve, etc.
Quite difficult.

In addition to the above, the three-way valve has a flow control system consisting of a flow meter and a flow adjustment valve on the nozzle side and the drainage side, respectively, and the flow rate is adjusted just before use, and the opening of the flow adjustment valve is fixed during use. There is a way to use it. Although this method is reliable for flow rate control, it is necessary to adjust the flow rate on the nozzle side and drain side each time the flow rate setting is changed, and a two-loop control device is required for one three-way valve. There are disadvantages such as .

The present invention solves the shortcomings of the prior art and is suitable for systems having a plurality of piping system blocks for each three-way valve, which requires selective use of nozzle groups and minimizing flow rate fluctuations during injection on/off. The present invention provides a flow rate control system that has high flow rate setting accuracy, is easy to adjust, and minimizes the number of control loops for flow rate control.

[Means for Solving the Problems] A flow control system according to the present invention for achieving the above object includes a three-way valve having ports on the water supply side, a nozzle side, and a drainage side, and a nozzle group on the nozzle side of the three-way valve. It has multiple open/close valves that can be selected, and a piping system with a variable throttle mechanism on the three-way valve drainage side. The present invention is characterized in that a plurality of the flow rate control blocks, which can provide a preset value and set a predetermined aperture value, are arranged in parallel, and the three-way valves can be freely switched.

Further, in the flow control blocks arranged in multiple rows in parallel, the opening degree of the flow rate regulating valve arranged on the upstream side of the three-way valve is fixed, and the three-way valve is switched before and after switching in units of control blocks. It is characterized in that the opening degree of the throttle mechanism on the drainage side that makes the subsequent flow rates equal is given as a preset value.

The details of the present invention will be explained below with reference to the drawings.

Figure 1 shows the basic configuration of the present invention, in which the water supply side,
Piping having a three-way valve 1 having ports on the nozzle side and a drainage side, a plurality of valves 7 that can be opened and closed to select a nozzle group 6 on the nozzle side of the three-way valve 1, and a variable throttle mechanism 5 on the drainage side of the three-way valve. It is made up of a plurality of flow rate control blocks each having a system (three systems in the figure) arranged in parallel.

FIG. 2 shows a method of equalizing the pressure loss on the nozzle side and the drain side of the three-way valve for a set flow rate. In the figure, 1 is a three-way valve, 6 is a nozzle, and 7 is an on-off valve. Reference numeral 8 denotes an opening adjustment valve, which receives opening information from a computer according to the number of nozzles in use, which is determined as a result of the operating conditions of the on-off valve 7, and the opening determines the pressure drop on the drainage side relative to the set flow rate. The piping resistance can be adjusted to be equal to that on the nozzle side.

Assuming that the pressure drop in the piping system is H1, the flow rate is Q, the internal area of the piping is A, and the flow velocity is ■, the relationship between the three is as follows.

v=Q/AH=ζ×%×■2/g (ζ is the piping resistance coefficient, g is the acceleration of gravity) The pressure loss is proportional to the square of the flow rate. Further, ζ is a value specific to the piping system, and the pressure loss after the three-way valve is released to the atmosphere when a nozzle is used, so the pressure loss is balanced according to the flow rate. The pressure loss on the nozzle side of a three-way valve mainly consists of the piping pressure loss to the nozzle and the nozzle pressure loss. If the number of nozzles changes, the piping resistance coefficient will also change, so naturally the flow rate, which is in a balanced relationship with the pressure loss on the nozzle side, will change. If the piping resistance coefficient on the drainage side of the three-way valve can be set equal to that on the nozzle side of the three-way valve, it is considered that the flow rate fluctuation when switching the three-way valve is caused only by an error in the setting of the piping resistance coefficient.

Note that 9 is a flow meter and 10 is a flow rate regulating valve, which are arranged on the upstream side of the three-way valve. The flow rate control of the system is performed by a flow rate control loop of a flow meter 9 and a flow rate regulating valve 10. As mentioned above, if the piping resistance coefficients on the three-way valve nozzle side and the drainage side are equal, the flow rate when switching the three-way valve will be theoretically equal, so by using this characteristic, the opening degree of the three-way valve drainage side can be adjusted. The opening degree of the adjustment valve 8 is determined.

In the above explanation, we have described the opening adjustment using one valve, but due to constraints such as the flow rate control range, it is recommended to consider the throttling mechanism on the drainage side of the three-way valve as an aggregate of multiple throttling mechanisms as shown in Fig. 3. is also possible. In this case, by selecting the valve 7' of the resistance piping body 5' which has various piping resistances, the same effect as the opening adjustment of the three-way drain side opening adjustment valve 8 in the above self-explanation can be obtained. can get.

The method will be explained below. By setting the on-off valve 7, the piping resistance coefficient on the three-way valve nozzle side becomes a unique value. The purpose of this adjustment is to replace this eigenvalue with the opening degree of the opening adjustment valve 8 using the following procedure. After setting the on-off valve 7, first fix the opening degree of the flow rate adjustment valve IO,
Fluid is caused to flow to the three-way valve nozzle side, and the flow rate measured by the flow meter 9 when the flow rate is stable is determined. Next, with the three-way valve switched to the drain side, the opening degree of the valve 8 is manually changed to adjust the flow rate at a stable time to the flow rate on the nozzle side. After the adjustment is completed, the three-way valve opening degree is stored on the computer table. The opening degree of the valve 8 described above is stored for each case of the usage conditions of the on-off valve 7. When using the piping system shown in Figure 3, when setting the on-off valve 7, at the same time
' is set, and the orifice of the piping resistor 5' is adjusted in the same manner as described above.

4 and 5 are diagrams in which the control blocks of FIG. 2 are arranged in parallel in a plurality of columns. Flowmeter 9 and flow rate adjustment valve lO in Figure 4
As long as the accuracy in the adjustment stage of the opening adjustment valve in step 8 allows,
They can be integrated like the flowmeter 11 and flow rate adjustment valve 12 in FIG. In Figure 5, where multiple rows of control blocks are covered by one flow rate control loop, the opening angle adjustment for each condition of the three-way valve nozzle side and the drainage side is performed without changing the conditions of the three-way valves of the control blocks other than those to be adjusted. In this case, it is possible to switch only the target three-way valve. Unlike when adjusting in a single row, the flowmeter used is a flowmeter for measuring large flow rates, so economical integration of control blocks can be achieved by considering the adjustment accuracy of flowmeter measurement error factors.

[Embodiment] An example in which the system of the present invention can be applied to a flange water cooling device for H-beam steel will be explained with reference to FIGS. 6 and 7. FIG. 6 shows an actual device diagram, and FIG. 7 shows a control procedure block diagram.

A multi-stage nozzle group 13 is used for steel materials transported in the H posture.
The flange 14 is cooled by jetting more water. The selection of the nozzle group is performed by selecting a stage corresponding to the flange width by opening/closing the opening/closing valve 7 shown in FIG. In order to satisfy the steel cooling conditions, the control block is divided into a plurality of control blocks as shown in FIGS. 4 and 5, and the cooling pattern is changed by switching the three-way valve to the nozzle side or the drain side.

In conjunction with the setting of the opening/closing valve, the opening degree of the opening adjustment valve 8 shown in FIG. 6 is given for each control block from a computer table. The opening degree of the opening adjustment valve is a value determined by matching the piping resistance coefficients on the nozzle side and the drain side of the three-way valve according to the above-mentioned procedure. When using multiple piping resistors, select the opening/closing valve for the piping resistor.

Next, the flow rate in the control block registered for each size is set.

Since the system in the example is acceptable in terms of accuracy, the fifth
Although the control loop shown in the figure is an aggregation of multiple rows of control blocks, since the piping resistance coefficients after the three-way valve are equal, it is hardly affected by fluctuations when switching the three-way valve. In addition, the flow rate setting using 11°I2 shown in Figure 5 is possible while fluid is flowing to the three-way valve drainage side, that is, it is possible without injecting coolant to the line side, so the impact on operation is extremely small. .

[Effects of the Invention] According to the present invention described above, a flow rate control system using a three-way valve has the advantage that it can support strict flow rate control, has small flow rate fluctuations when switching valves, and is easy to adjust. be. Therefore, it is ideal for application to a flange cooling means for H-beam steel that requires strict flow control and complicated three-way valve switching.

[Brief explanation of the drawings] Fig. 1 is a piping system diagram showing a basic configuration example for carrying out the present invention, Fig. 2 is a piping system diagram showing a method of equalizing the pressure loss on the nozzle side and the drain side of a three-way valve. System diagram, Fig. 3 is a piping system diagram showing another example of Fig. 2, Figs. 4 and 5 are system diagrams in which control blocks of Fig. 2 are arranged in multiple rows in parallel, and Fig. 6 is a piping system diagram showing another example of Fig. 2. Fig. 7 is a block diagram showing the control procedure of Fig. 6;
FIGS. 8 and 9 are diagrams showing conventional flow control systems. l... Three-way valve, 5... Variable throttle mechanism, 6... Nozzle group, 7... Opening/closing valve, 8... Opening adjustment valve,
9...Flowmeter, IO...Flow rate adjustment valve, 13...Multi-stage nozzle group, 14...Flange

Claims (1)

[Claims] 1. A three-way valve with ports on the water supply side, nozzle side, and drainage side; a plurality of valves that can be opened and closed to select nozzle groups on the nozzle side of the three-way valve; and a variable throttle on the drainage side of the three-way valve. The flow rate control block has a piping system with a mechanism, and provides a preset value to the throttling mechanism on the drainage side so that the pressure drop on the drainage side with respect to the set flow rate is equal to that on the nozzle side, and can set the restriction to a predetermined throttling value. A flow control system characterized by arranging multiple systems in parallel and freely switching three-way valves. 2. In the flow rate control blocks arranged in multiple rows in parallel, the opening degree of the flow rate regulating valve placed upstream of the three-way valve is fixed, and the flow rate before and after switching of the three-way valve is determined for each control block. 2. The system according to claim 1, wherein the opening degree of the drainage-side throttling mechanism at which the values are equal is given as a preset value.