JPS59184921A - Method and device for controlling fluid pressure - Google Patents

Abstract

PURPOSE:To supply a fluid with high efficiency by selecting the proper pressure in accordance with the switching states of valves provided to plural branch pipes of a main pipe and controlling the number of revolutions of a pump motor based on the deviation between said proper pressure and the pressure generated actually. CONSTITUTION:A main pipe 4 of fluid is branched into five branch pipes 5, and valves V1-Vn are opened and closed in accordance with a desired quantity of fluid. The flow rate signal detected by a flow rate converter 9 of the pipe 4 is fetched to a pressure operator 12, and the set pressure value corresponding to the desired quantity of fluid is calculated from the flow-rate/pressure characteristics f1-fn obtained previously. Then the characteristics fi is selected 13 and the pressure signal P2 is delivered. The pressure of the pipe 4 is detected 6 to obtain the pressure signal P1. The signal P is obtained from signals P1 and P2 through a prescribed operation 7. Then the number of revolutions of a pump motor is controlled 8 to drive the motor 2. A flow rate controller 10 is controlled by the characteristics fi so that a flow rate control valve 11 is fully opened. Thus the pressure is set in response to the switching state of the valve, and the necessary motive power of a pump is minimized without causing the shortage of fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a t-fluid delivery system in which a plurality of branch pipes are branched and connected downstream of a base pipe, and each branch pipe is provided with a fluid cutoff valve for blocking the flow of fluid. The present invention relates to a method and apparatus for controlling fluid pressure in, for example, a combustion air supply system of a heating furnace. Hereinafter, a combustion air supply system for a heating furnace will be explained as an example.

The combustion air supply system to each burner in the heating furnace has a configuration in which combustion air is distributed and distributed to each burner through a plurality of branch pipes branched from a single base pipe connected to a base blower. Each branch pipe is equipped with a combustion air cutoff valve.

The flow rate of combustion air in such a feeding system is controlled by a flow control valve installed in the base pipe, but if the combustion air pressure in the base pipe is lower than the appropriate value, Even if the flow rate control valve is fully opened, the specified combustion air flow rate cannot be secured, resulting in incomplete combustion.On the other hand, if the combustion air pressure is too high than the appropriate value, , ζ, which causes an increase in power consumption if pressure control is performed by controlling the rotation speed of the blower. In addition, when thinning out the burners in order to secure an appropriate φ-nare flame length and stabilize combustion when the combustion load is reduced, in other words, when the combustion air cutoff valve of the branch pipe is fully opened, it is especially important to Since the pressure drop increases, it becomes necessary to increase the combustion air pressure before the shutoff valve closes in order to supply an appropriate amount of combustion air to the burner. Therefore, conventionally, control is performed by setting the overall combustion air pressure to be high so as not to cause the shortage of combustion air. Therefore, the electric power cost of the blower is high.

This invention has been made to solve the above-mentioned conventional problems, and is a fluid pressure control method and apparatus that allows optimal pressure setting even when thinning burners, that is, when opening and closing the combustion air cutoff valve of each branch pipe. This is what we propose.

This invention method is applicable to - a fluid supply system in which a plurality of branch pipes are branched and connected downstream of a base pipe to which fluid is supplied by a base fluid machine, and a fluid cutoff valve is installed in each branch pipe; In the fluid pressure control method, the flow rate control valve of the base pipe section is controlled according to the deviation between the fluid flow rate value of the base pipe section and the set flow rate value, and the flow rate control valve of the base pipe section is controlled according to the flow rate-pressure characteristic of each branch pipe determined in advance. Calculate the set pressure value of each branch pipe corresponding to the flow rate value of the pipe section, select the set pressure value according to the number of shutoffs of each fluid cutoff valve, and calculate the selected set pressure value and the fluid pressure value of the base pipe section. The fluid feeding output of the fluid machine is controlled according to the deviation from the fluid machine.

That is, in this invention method, the set pressure value corresponding to the fluid flow rate of the base pipe is calculated based on the flow rate-pressure characteristic determined in advance, and the set pressure value is calculated according to the number of shutoffs of the fluid cutoff valve of each branch pipe. In this method, the fluid pressure, that is, the fluid feed output of the fluid machine, is controlled according to the deviation between the set pressure value and the detected pressure value.

According to this method, it is possible to set the pressure according to the number of shutoffs of the fluid cutoff valve of each branch pipe, so it is possible to secure a predetermined flow rate without having to set the overall fluid pressure high. Machines can be used effectively.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Here, a case will be described in which the present invention is applied to a combustion air supply system for a heating furnace.

The drawing is a block diagram showing the supply system that supplies combustion air to each burner of the heating furnace and its control device.
(1) is a blower, (2) is a motor that drives the blower, (
3) is a preheater that preheats the combustion air sent from the blower, (4) is a base pipe for supplying combustion air to branch pipes to be described later, and (6) is a t-branch connected to the base pipe. tube, (B,
) to (Bn) are burners attached to the tip of each branch pipe, (
V, ) to (Vn) are combustion air cutoff valves attached to respective branch pipes corresponding to the burners.

(6) is a pressure converter that detects the combustion air pressure in the base pipe section and converts it into an electric signal, and (7) is a combustion air pressure regulator, which includes a set pressure signal P2 and a detected pressure signal P, which will be described later.
, the blower drive motor (
2) outputs the rotational speed signal P. (8) is a rotation speed control device which inputs the rotation speed signal P and controls the drive motor (2) to a predetermined rotation speed.

(9) is a flow rate converter that detects the amount of combustion air sent from the blower and converts it into an electrical signal, and (lO) is a flow rate converter that detects the amount of combustion air sent from the blower and converts it into an electrical signal. A flow controller that performs calculations and outputs a valve opening signal;
(The valve is a flow rate control valve that manually controls the valve opening signal to adjust the combustion air flow rate.

(12) is a pressure calculator that inputs the detected flow rate signal output from the flow rate converter (9) and calculates a set pressure value corresponding to the detected flow rate signal based on the flow rate-pressure characteristic determined in advance. A plurality of flow rate-pressure characteristics (fl) to (fn) are provided corresponding to the number of combustion air cutoff valves provided in the pipe. FIG. 2 is a chart illustrating flow rate-pressure characteristics. (I3) selects the set pressure signal output from the pressure calculator θ2) according to the number of shutoffs by the shutoff commands (CMD, ) to (CMD n) for each combustion air cutoff valve (■) to (vn). This is a signal selector that outputs the selected set pressure signal P to the combustion air pressure regulator (7).

In addition, the flow rate-pressure characteristic (f,) of the pressure calculator (12) ~
(fn) is determined so that the valve opening degree of the flow rate control valve (11) is close to full open in any flow rate range, that is, the characteristic is determined so that the flow rate control valve (11) does not cause pressure loss in itself as much as possible.

Next, the control operation will be explained.

Normal combustion air flow rate control is performed by giving a valve opening signal from a flow rate regulator (lO) to a flow rate control valve (11) based on a set flow rate signal, and error correction is performed using a flow rate converter (9). ) A predetermined calculation is performed on the deviation between the detected flow rate and the set flow rate to control the flow rate control valve (11).

Currently, due to the reduction in the combustion load of the heating furnace, burners are being thinned out to ensure the appropriate length of the burner frame and to stabilize combustion, and a predetermined number of combustion air cutoff valves (V, ) to (vn) are being thinned out. If a situation arises in which the pressure is shut off or fully opened, the set pressure signal is determined by the following method.

That is, the flow rate signal detected by the flow rate converter (9) installed in the base pipe (4) is taken into the pressure calculator 02), and the combustion air is Calculate the set pressure value corresponding to the flow rate 4゜In this case,
(f,) is the characteristic when the number of valves is 0, (f2) is the characteristic when the number is 1, and (f,) is the characteristic when the number is n-4, so that each combustion air cutoff valve ( Vυ〜(vl)
For example, if the number of shutoffs due to double-through shutoff command (CMD, ) ~ (CMD, ) is O, the set pressure signal of (f,) is
If the number of interruptions is 1, the set pressure signal P of (f2)! are selected by the signal selector (I:il), and the set pressure signal P2 is output to the combustion air pressure regulator (7).

This pressure regulator (7) has a pressure transducer (
6) A predetermined calculation is performed on the deviation from the detected pressure signal P outputted from the rotation speed signal P, and the rotation speed control bag @(
8) controls the drive motor (2) of the blower (1).

What should be noted here is that the flow i − of the pressure calculator (12)
The pressure characteristics (f,) to (fn) are determined so that the valve opening degree of the flow rate control valve (+I) is close to full open in any flow rate range, that is, so that pressure loss does not occur in the flow rate control valve itself as much as possible. There is no need to apply pressure with a considerable margin in advance.

As explained above, according to the present invention, it is possible to set the pressure immediately in response to a command to shut off a branch pipe when thinning burners, etc., there is no shortage of combustion air flow rate, and the power consumed by the blower is minimized. Since it is possible to control the combustion air pressure, it is possible to stabilize the fluid supply in systems where fluid is supplied through multiple branch pipes connected to a base pipe, such as the combustion air supply system of a heating furnace. It is possible to improve economic efficiency and economic efficiency.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a chart showing flow rate-pressure characteristics of the pressure calculator in the same. DESCRIPTION OF SYMBOLS 1... Blower, 2... Drive motor, 3... Preheater, 4... Base pipe, 5... Branch pipe, 6... Pressure transducer,
7... Combustion air pressure regulator, 8... Rotation speed control device, 9... Flow rate converter, 1o... Flow rate regulator, 11
...Flow control valve, 12...Pressure calculator, 13...
Signal selector, B1~Bn... Burner, ■~V...
Fluid cutoff valve, f, ~fn...Flow rate-pressure characteristics, Pl.
...Detected pressure signal, P=...Setting pressure signal, P...
Rotation speed signal. Applicant Sumitomo Metal Industries Co., Ltd. Agent ・Oshi 1) Yoshihisa,'', ::':'i
・ ,B

Claims (1)

[Scope of Claims] 1 - A fluid supply system in which a plurality of branch pipes are branched and connected downstream of a base pipe to which fluid is supplied by one fluid machine, and a fluid cutoff valve is installed in each branch pipe. In the fluid pressure control method of the system, the base pipe part P flow control valve is controlled according to the deviation between the fluid flow rate value of the base pipe part and the set flow rate value, and the flow rate-pressure characteristic of each branch pipe is determined in advance. Calculate the set pressure value of each of the six branch pipes corresponding to the flow rate value of the base pipe part, select the set pressure value according to the number of shutoffs of each fluid cutoff valve, and combine the selected set pressure value and the base pipe part. 1. A fluid pressure control method comprising controlling a fluid feed output of a fluid machine according to a deviation from a fluid pressure value of . In a fluid delivery system in which a plurality of branch pipes are connected to the downstream side of a base pipe to which fluid is supplied by two fluid gateways, and each branch pipe is equipped with a fluid cutoff valve, the base pipe part A pressure oil extractor and a flow rate detector that detect the fluid pressure and flow rate, multiple pressure calculators that have flow rate-pressure characteristics according to the number of shutoffs of the fluid cutoff valve, and a pressure calculator that takes the pressure signal as input and sets the pressure signal. comprises a signal selector selected according to the number of shutoffs of the fluid cutoff valve, and a fluid pressure regulator that emits a rotation speed signal according to the deviation between the detected fluid pressure signal of the base pipe section and the set pressure signal, and the rotation speed A fluid pressure control device configured to control the fluid feed output of a fluid machine based on a signal.