JPS5929207Y2 - fluid flow control device - Google Patents

Description

[Detailed description of the invention] This invention relates to a fluid flow rate control device, and in particular, when fluid is supplied through a plurality of branch pipes connected to a main pipe, for example, the flow rate of combustion air to each burner in a heating furnace is controlled. This invention relates to a control device suitable for controlling such as.

The method of controlling the flow rate of combustion air to each burner in a conventional heating furnace is to supply combustion air to a single base pipe connected to a base blower, and then to multiple branch pipes that branch from this base pipe. Accordingly, combustion air was branched and fed to each burner, and each branch pipe was provided with a flow rate detection controller to control the air flow rate fed to each burner.

Therefore, if the pressure inside the base pipe becomes insufficient, it becomes impossible to obtain a necessary and sufficient flow rate of combustion air, so the pressure inside the base pipe is set to a high pressure with a considerable margin to supply combustion air.

For this reason, in the past, the effective utilization rate of blower power was low and energy loss was significant.

This invention was devised to solve these conventional problems, and aims to provide a fluid flow rate control device with a high effective utilization rate of fluid mechanical power.

The fluid flow rate control device according to this invention determines the resistance characteristics of each branch pipe based on the flow rate control status of the flow rate detection controller, and determines the fluid pressure toward the base pipe to obtain a predetermined flow rate based on the resistance characteristics. Furthermore, the highest pressure among the fluid pressures toward the base tube corresponding to each branch pipe is determined, and the fluid machine is controlled so as to make the fluid pressure toward the base tube coincide with this maximum pressure.

Next, an embodiment of the fluid flow rate control device according to the invention for controlling the flow rate of combustion air to each burner in a heating furnace will be described with reference to the drawings.

In the first time, the blower 1 sends combustion air A to multiple branch pipes 3 through the base pipe 2 having one air preheater R, and from this branch pipe 3 to each band burner (not shown) burns. When supplying the combustion air A, the flow rate detection controller 4 controls the flow rate in each branch pipe 3, and the rotation speed controller 5 controls the rotation speed of the blower 10 to supply the combustion air A in the base pipe 2.
The flow rate detection controller 4 includes a flow rate detector 6 and a flow rate control valve 7, and adjusts the opening degree of the valve 7 so that the flow rate actually measured by the flow rate detector 6 matches a predetermined flow rate. do.

A pressure detector 8 is provided in the base pipe 2, and this pressure detector 8
is connected to the rotation speed controller 5.

The rotation speed controller 5 controls the pressure Po of the air A in the base pipe 2 actually measured by the pressure detector, and the maximum value of the required pressure in the base pipe 2 to supply a predetermined flow rate to each branch pipe 3. Pmax
The rotation speed of the motor 9 that drives the blower 1 is adjusted based on the difference ΔP (-Pmax-P o ).

The flow rate detection controller 4 includes a computing unit that determines the resistance characteristic of the branch pipe 3 according to the opening degree of the valve 7 and calculates the air pressure P in the base pipe 2 to obtain a predetermined flow rate based on this resistance characteristic. 10 are connected.

In order to execute this calculation, the original resistance characteristics of each branch pipe 3 including the burner etc., the resistance characteristics of the valve 7 according to the opening degree of the valve 7, a predetermined flow rate, etc. are input into the calculation unit 10. There is.

A selection circuit 11 is connected to the calculator 10, and the pressure P for each branch pipe 3 is input to this selection circuit 11.

The selection circuit 11 compares the pressures P for each branch pipe 3 to determine the maximum pressure Pmax, and inputs this Pmax to the rotation speed controller 5.

The pressure detector 8 and the selection circuit 11 further include an alarm 12.
is connected to the alarm 12, which calculates ΔP and outputs a command signal S to stop the supply of heavy oil to the burner, assuming that the air flow rate cannot be controlled when ΔP exceeds a certain set value.

The rotation speed controller 5 calculates the pressure difference △P and also calculates the pressure difference △P.
The rotational speed of the blower 1 is controlled to make it zero, and air is thereby fed with the minimum necessary pressure Po, that is, with the minimum necessary power of the blower 1.

Therefore, the utilization rate of blower power can be maximized.

The relationship between the required flow rate QCNm''/h of combustion air A and the electric power E (KW) consumed by the motor 9 to feed this combustion air A is as shown in FIG. Case according to example (shown by solid line in the figure).

) is based on the conventional example (indicated by a broken line in the figure).

), it can be seen that the power consumption E is much lower than that of

Although this embodiment relates to the supply of combustion air to a heating furnace burner, the present invention can also be applied to the supply of other fluids.

Furthermore, the fluid machine is not limited to a centrifugal air machine, but may also be a positive displacement air machine, a centrifugal type, or a positive displacement hydraulic machine.

However, due to the need for pressure control, a surge tank should be used in conjunction with positive displacement fluid machines.

As mentioned above, the fluid flow control device according to this invention determines the resistance characteristics of each branch pipe based on the flow rate control status of the flow rate detection controller, and calculates the fluid pressure in the base pipe direction based on this resistance property to obtain a predetermined flow rate. Then, the highest pressure among the base pipe direction fluid pressures corresponding to each branch pipe is determined, and the fluid machine is controlled so that the base pipe direction fluid pressure matches this maximum pressure.

This has the excellent effect of increasing the effective utilization rate of fluid mechanical power.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the fluid flow rate control device according to this invention, and Fig. 2 shows the relationship between the required flow rate Q of combustion air and the power consumption E in the embodiment (solid line) and the conventional example (broken line). ) is a graph comparing 1...Blower, 2...Base pipe, 3...
...Branch pipe, 4...Flow rate detection controller, 5...
...Rotation speed controller, 6...Flow rate detector, 7.
...Flow control valve, 8...Pressure detector, 9
...Motor, 10...Arithmetic unit, 11.
...Alarm. A...Combustion air, R...Air preheater, P o, P, Pmax...Pressure, S
・・・・・・Command signal.

Claims (1)

[Scope of utility model registration request] Multiple branch pipes are connected to a single base pipe to which fluid is supplied by a single fluid machine, and each branch pipe has flow rate detection that controls the fluid flow rate to bring the fluid flow rate of each branch pipe close to a predetermined flow rate. A controller is provided, and the flow rate detection controller determines the resistance characteristics of each branch pipe based on the flow rate control status of the flow rate detection controller, and calculates the required fluid pressure in the base pipe to obtain a predetermined flow rate based on this resistance property. A calculation unit for determining the pressure is connected, a selection circuit for determining the highest pressure among the required fluid pressures in the base pipe is connected to the calculation unit, a pressure detector is provided in the base pipe for detecting the fluid pressure in the direction of the base pipe, and this The fluid machine is connected to the pressure detector and the selection circuit so as to compare the maximum pressure with the actual measured value of the base fluid pressure and make the base fluid pressure match the maximum pressure. Control device.