JPH0140943B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a leak detection device for a load pipeline such as a heat exchanger using a flow meter.

In general, many devices are known for detecting leakage of fluid flowing inside piping. In particular, when fluid leaks from the load pipes of a blast furnace cooling system or heat exchanger, it not only causes a large economic loss and pollutes the environment, but also poses a risk of a steam explosion in the heat exchanger. even occurs,
From a safety management perspective, it is necessary to monitor the presence or absence of leaks from these devices.As this device, flowmeters are installed at the inlet and outlet of the flow path, and leakage can be detected by measuring the difference in flow rate between the two flowmeters. Many detection technologies have been developed.

For example, Figure 1 shows the patent application filed by the applicant.
56-118483 [Flow rate difference detection device] This is an overview of the invention, and this unpublished prior art will be explained below with reference to the drawings.

Reference numeral 1 denotes a flow pipe, 2 a first flow meter disposed on the inflow side of the flow pipe, 3 a second flow meter disposed on the outflow side of the flow pipe, and 4 a flip-flop circuit. This is a flow rate counting circuit. Reference numeral 5 indicates an oscillator for transmitting standard pulses, and 6 indicates a scaler, which is connected to the oscillator 5 to measure the instrumental error of the flowmeter and correct the inherent error. 7 is an up-down counter, 8 is a digital comparator, 9 is a counter, and 10 is an alarm circuit.

The operation of the prior art flow rate difference detection device configured as described above will be explained.

First, in order to count the change in the pulse period due to leakage, that is, the period difference, transmitted from the flowmeters 2 and 3 disposed on the inflow side and the outflow side of the flow path piping 1, respectively, the flow rate counting circuit 4 uses the input signal is divided into one count, and the rising signal of this one count is transmitted as a one-shot signal.

Then, while the output signal from the flow rate counting circuit 4 is 1, the standard oscillation signal from the oscillator 5 is inputted into the scaler 6, where the meter coefficients of both flowmeters 2 and 3 are matched by performing instrumental error correction. It is input to the up-down counter 7.

If a leak occurs, the flow rate will be smaller on the outflow side than on the inflow side depending on the amount of leakage, so for example, the pulse count value of the second flow meter 3 on the outflow side should be
When it is 1000, the counted value of the first flowmeter 2 on the inflow side is always less than 1000. Therefore, the pulse signal inputted to the up-down counter 7 enters the downside counter and is sequentially subtracted from the previously counted value 1000. The numerical difference between the count values detected in this way is determined by the digital comparator 8.
If the value is larger than the value set in , output signal 1 is output and counter 9 counts. When the counted value reaches a preset value, the next-stage alarm circuit 10 is activated to detect a flow rate leak.

According to this unpublished prior art, both flow meters 2,
The existence and amount of leakage can be detected in a short time based on the difference in pulse period with respect to the unit flow rate of 3. Furthermore, the leakage amount can be compared with a set value, and the alarm circuit 10 can easily notify the leakage amount using a lamp, an alarm sound, or the like.

However, like a heat exchanger, both flowmeters 2,
Even if the piping configuration allows the flowmeters 2 and 3 to be installed relatively close together, it is necessary to quickly detect the presence or absence of a leak if the device integrates and compares the periodic pulses of both flowmeters 2 and 3 as described above. In such cases, it may take a relatively long time considering the resolution, and as a result, the leakage amount must be detected after it has increased, which may be problematic in practice.

Furthermore, in the above-mentioned prior art, in the event that a failure occurs in the first flowmeter 2 or the second flowmeter 3, whether the output signal is due to leakage of a load such as the piping 1, or whether each flowmeter 2 , 3, or both of the above causes is difficult to discern.

This invention was made by focusing on the above points, and normally two flowmeters are used to detect leakage in the load pipe, and the flow path of the load pipe is switched as necessary. The object of the present invention is to provide a leakage detection device that periodically detects and corrects the difference in flow rate between two flowmeters.

An embodiment of the present invention will be described below with reference to FIG.

Note that the same configurations as those of the above-described prior art shown in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

It is assumed that 1a is a load such as a heat exchanger, and a desired fluid is flowing in the direction of the arrow.

Reference character a denotes an inflow side pipe attached to the inlet side of the heat exchanger 1a, and is equipped with a first flow meter 2. Similarly, b is
A second flow meter 3 is provided on the outflow side piping attached to the outlet side of the heat exchanger 1a. Note that G is a first valve provided on the outlet side of the first flow meter 2 of the inlet pipe a. H is the outflow side pipe b
This is a second valve provided on the inlet side of the second flowmeter 3. A and B are valves provided on the inflow side and the outflow side of the first flowmeter 2, respectively. C and D are valves provided on the inflow side and the outflow side of the second flowmeter 3, respectively. c is the load piping 1a side of the first valve G and the first flowmeter 2
This is a first bypass conduit provided to connect the inflow side of the inlet. d is a second bypass line provided to connect the load line side of the second valve H and the outflow side of the second flow meter 3. E
is a third valve provided in the first bypass conduit c. F is a fourth valve provided in the second bypass line d. e is provided to connect a branch point between the first valve G and the outflow side of the first flowmeter 2 and a branch point between the second valve H and the inflow side of the second flowmeter 3. This is the third bypass line. I is the fifth valve provided in the third bypass line. J is a controller which inputs signals to the operating ends of the first to fifth valves and valves A, B, C, and D to open and close the valves.

A scaler 6 is connected to the oscillator 5, works in conjunction with the up-down counter 7, performs instrumental error correction of both flowmeters 2 and 3, and further corrects the instrumental error of both flowmeters 2 and 3 based on the setting conditions of the scaler corresponding to changes in flow rate. A change in deviation between both flowmeters 2 and 3 is detected.

The operation of the present invention will be explained based on the above configuration.

The desired fluid usually flows out from the inflow side piping a through the heat exchanger 1a and both flow meters 2 and 3 before and after the heat exchanger 1a, and then flows out to the outflow side piping b. In this case, the third valve E, the fourth valve F, and the fifth valve I are closed, and the other valves are left open.

Now, if you want to measure the flow rate difference between both flowmeters 2 and 3, open the fifth valve I of the third bypass pipe e, and open the first valve G, second valve H, and third valve E. Then, the fourth valve J is closed to stop the fluid flowing to the heat exchanger 1a. These valve switching operations can be performed instantaneously by sending a signal from the controller J to the operating end of each valve.

Therefore, the desired fluid flows through the first flow meter 2 disposed on the inflow side piping a, flows into the bypass conduit e, and further passes through the second flow meter 3 disposed on the outflow side piping b.

In this state, first, a flow measurement pulse signal proportional to the flow rate transmitted from the flow meter 3 is input to the flow rate counting circuit 4. The flow rate counting circuit 4 divides the frequency of this input signal and transmits the rising signal of one count as a one-shot pulse. Next, the high frequency received from oscillator 5, for example 10K.
A standard pulse of Hz is input in synchronization with this one-shot pulse, and the up-down counter 7 counts the timing pulses that occur during one count. Similarly, the timing pulses of the pulse signal proportional to the flow rate emitted from the flowmeter 2 are counted in the manner described above. By correcting the count signals of both flowmeters 2 and 3 by applying a scaler 6, the inherent deviation of both flowmeters 2 and 3 can be stored in the register 11 periodically or when necessary. , can be counted at high speed and with high precision.

Next, the controller J is operated to simultaneously open the first valve G and the second valve H, and the third valve
When valve I is closed, the desired fluid flow path is switched to the normal state described above. In this state, when the flow measurement pulses from both flowmeters 2 and 3 are subjected to the above calculation processing, the scaler 6 and up-down counter 7 calculate the value under the arbitrary setting conditions of the scaler 6 corresponding to the change in flow rate. Count the timing pulses of each flow meter 2, 3. Next, the digital comparator 8 compares this count value with the characteristic deviation value stored in the register 11 to measure the instrumental difference change between both flowmeters 2 and 3, that is, the amount of change in the flow rate difference. In addition, the digital comparator 8 has
A setting digital switch is provided, and the setting value of this switch can be changed. For example, when the amount of change in the deviation value of both flowmeters 2 and 3 is larger than the setting value, output signal 1 is output. Is possible.

If the alarm circuit is configured to issue an alarm upon receiving this output signal, fluid leakage from the heat exchanger 1a can be detected immediately.

In this way, the present invention can detect the presence or absence of leakage in the load pipe line, or the amount thereof, in an extremely short time and with high precision, so that necessary countermeasures can be taken immediately.

As explained above, this invention has the following advantages.

(1) With two flowmeters connected directly without any load, the inherent deviation values of both flowmeters are periodically checked by counting timing pulses proportional to the flow rates of both flowmeters. There are usually
If the alarm circuit is activated, it is possible to know that there is a fluid leak in the load, so that necessary measures can be taken immediately.

(2) Since the change in the characteristic deviation of both flowmeters corresponding to the amount of leakage is detected by counting timing pulses synchronized with high-frequency standard pulses, it is possible to detect the change in the characteristic deviation of both flowmeters in response to the amount of leakage. Since leaks can be detected, this method is particularly effective in detecting leaks of fluids that may be explosive.

(3) Electrically control the opening and closing states of the valves installed in the case of changing the fluid flow path for measuring the inherent deviation of the flowmeter and changes in the deviation, and replacing the flowmeter due to failure etc. The system allows instant switching, so there is no need to interrupt fluid transfer and stop the plant.

[Brief explanation of drawings]

In the drawings, Fig. 1 is a block diagram of the prior art invented by the present applicant, and Fig. 2 is a diagram showing a case where the inherent deviation correction device for a flowmeter according to the present invention is arranged in piping to a load such as a heat exchanger. FIG. 2 is a block diagram showing an embodiment. 1... Piping, 1a... Load such as heat exchanger,
2, 3...Flowmeter, 4...Flow rate counting circuit, 5...
Oscillator, 6... Scaler, 7... Up-down counter, 8... Digital comparator, 9
...Counter, 10...Alarm circuit, 11...Register, a...Inflow side piping, b...Outflow side piping,
c, d, e...bypass pipe line, A, B, C, D,
E, F, G, H, I...Valve, J...Controller.

Claims (1)

[Claims] 1 The first
A flowmeter is provided in the outflow side pipe, and a second flowmeter is provided in the outflow side pipe, and leakage in the load pipe is detected by detecting a flow rate difference between the second flowmeter and the first flowmeter. In the detection device, a first valve is provided on the outlet side of the first flowmeter of the inflow side piping,
A second flowmeter is installed on the inlet side of the second flowmeter of the outflow side piping.
a valve is provided, and the first bypass line is connected to the first bypass line.
A second bypass pipe is provided to connect the load pipe side of the second valve and the inflow side of the first flowmeter, and a second bypass pipe is provided to connect the load pipe side of the second valve and the outflow side of the second flowmeter. a third valve is provided in the first bypass conduit, a fourth valve is provided in the second bypass conduit, and the third bypass conduit is connected via a fifth valve. connected to a branch point between the first valve and the outflow side of the first flowmeter and a branch point between the second valve and the inflow side of the second flowmeter, and connects the first to fifth valves. A controller that opens and closes is provided, and when the flow rate difference between the first flowmeter and the second flowmeter is detected by operating the controller, the fifth valve is opened, the other valves are closed, and leakage is detected. 1. A leakage detection device for a load pipe line, characterized in that, at the time of detection, the third, fourth, and fifth valves are closed and the flow path can be switched so that the other valves are opened.