JPS6047536B2 - steam flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a so-called shunt flow meter, which is mainly used for measuring gases such as water vapor.

The internal fluid flow path of this type of flow meter consists of a straight pipe section into which an orifice J splate is inserted, and a side path that includes a metering turbine chamber, and a portion of the steam to be metered is placed on the upstream side of the orifice. After passing through a side passage and jetting out from a nozzle provided at the entrance of the metering turbine chamber to rotate the metering turbine, it is made to join the main flow again on the downstream side of the orifice.

A brake turbine chamber filled with a predetermined brake fluid is provided below the metering turbine chamber, and both turbine chambers are provided with a metering turbine and a brake turbine, respectively. The assembly consisting of the components is rotatably supported and configured to be freely rotated by steam etc. ejected from the nozzle.

Conventionally, the flow rate has been measured by transmitting this rotation to a mechanical rotation counter via an appropriate speed reduction device, or by providing an appropriate rotation detector and counting its output pulses. It is. In this type of flowmeter, the driving torque T1 by the metering turbine is proportional to the density r of the steam to be metered and the square of the volumetric flow rate ■, and the braking torque T2 by the braking turbine is proportional to the density γ of the braking fluid and the turbine rotation. It is proportional to the square of the number ω, and during steady rotation, and if k1 and K2 are proportional constants, or (where K, .k are meter constants, K=V卜γ, f is the oscillation frequency, f=Kω/KW is the weight flow rate, W=rv).

Therefore, in this type of flow meter, the meter constant K or k
Even if is known, it is not possible to immediately know the weight flow rate W or volumetric flow rate ■ from the turbine rotational speed ω or pulse oscillation frequency f, and the density r of the steam etc. measured by these ω or f
Alternatively, it is necessary to obtain W or ■ by multiplying the square root of the specific volume table by the above meter constant.

Therefore, conventionally, fully automatic and semi-automatic calculation devices have been used to perform this calculation.

Here, fully automatic type means that a detector is installed that can automatically or directly measure the density r of the steam, etc. to be measured, and this automatically measures the density r of the steam, etc., even when the pressure and temperature of the steam, etc. fluctuate. It calculates the above equation (1) or (2), and the semi-automatic method is a method that calculates the value of the density r of steam, etc., or the physical quantities that determine these (e.g., vapor pressure or temperature in saturated steam, etc.) or a physical quantity derived from the density r (for example, specific volume 1/
The value of r) is manually set, and the above calculation is performed based on the set value. However, these conventionally known arithmetic devices have had various problems.

First, regarding mechanical types, although the machines are complex, the usable range of density, pressure, etc. is narrow.
Moreover, the calculation accuracy was low.

In addition, this type of flow meter is required to have a small diameter of about 20 mm to a large diameter of 1000 mm or more, and the orifice plate used can be replaced and the hole diameter changed. As a result, it is required that the measurement range of a flowmeter be configured to be able to change appropriately at any time.Therefore, there are dozens of types of meters, and the reference value of the meter constant K or k also varies widely. Become something.

For this reason, in the past, there has been no mechanical or electronic computing device that can be used commonly across all types of flow transmitters and that can easily and reliably set meter constants, etc.

To explain more specifically, when replacing the flow rate transmitter used in combination or changing the orifice or normal pressure, etc., conventional electronic calculation devices have to perform complicated calculations according to the manual for meter constants etc. After doing so, various constants had to be reset according to the results, which was extremely inconvenient.

Furthermore, in the conventional apparatus, there was a problem in that the pitch of the constant to be set becomes rough depending on the conditions, making it impossible to obtain sufficient accuracy. The present invention has been developed based on the above-mentioned viewpoints, and its purpose is to be able to easily connect to any of a wide variety of flow rate transmitters, even when the orifice, normal pressure, etc. are changed. An object of the present invention is to provide a split-flow steam flowmeter equipped with an electronic calculation device that can be easily handled by simply switching a setting switch without using special numerical tables or performing any calculations. .

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

The drawing is an explanatory diagram showing one embodiment of the steam flow meter according to the present invention, in which 1 is a flow transmitter, and 2 and 3 are steam piping that transports saturated steam at a constant pressure from the lower part to the upper blade in the drawing. The flow rate transmitter 1 includes a straight pipe housing 5 into which the orifice 4 is inserted, an orifice insertion hole cover 6, a metering turbine chamber housing 7,
Its lid body 8, nozzle plate 9, brake turbine chamber housing 1
0, its lid body 11, metering turbine 12, braking turbine 1
3. Consists of a rotating main shaft 14, magnets 15, 15, and a magnetic sensor 16. Further, 17 is a preamplifier, 18 is an input pulse waveform shaping circuit, 19 is a P-ROM1O, and 21 is a first and second frequency divider, respectively.
25 and 26 are a 1-frequency frequency generator and T which constitute an auxiliary frequency divider.
Bistable element, 27 and 28 are selector switches for frequency division ratio selection, 29 is an electromagnetic counter, 30 is a connecting pipe diameter coding circuit, 31 is an orifice type coding circuit, and 32 is a code for steam pressure to be measured. circuit, 33,3
4 and 35 are three-digit m-adic M setting circuits that set the frequency division ratio of the second frequency divider 21 in order to correct the instrumental error of the flow rate transmitter 1.

The metering turbine chamber housing 7 defines a metering turbine chamber 7 a together with a lid 8 and a nozzle plate 9 and also constitutes side passages 7 b and 7 c to the orifice 4 . The brake turbine chamber housing 10 defines a brake turbine chamber 10a together with its lid 11, which is filled with water as a brake fluid.

The metering turbine 12 and the braking turbine 13 are connected to the rotating main shaft 14
The braking turbine 13 is connected to a magnet 15,
15 is installed.

Therefore, these turbine chamber casings 7 and 10, as well as the various parts installed inside and outside of them, have the same shape and the same dimensions even if the diameter D of the straight pipe part casing 5 and the opening ratio ψ of the orifice 4 are different. These are commonly used.

Most of the steam flowing in from the steam pipe 2 passes through the orifice 4, but part of it is diverted through the side passage 7b and flows from the nozzle holes 9a, 9a of the nozzle plate 9 to the metering turbine chamber 7a.
It is injected into the interior, causing the metering turbine 12 to rotate together with the braking turbine 13, and then passes through the side channel 7c and joins the main stream downstream of the orifice 4. The rotation of the braking turbine 13 is detected by the magnetic sensor 16 and converted into a pulse signal, which is passed through the preamplifier 17 and the waveform shaping circuit 18 to the first frequency divider 20.
sent to.

The frequency division ratio of the first frequency divider 20 is -N- (however, N is
100001000J). Above, 10,000
N is set by the output data of P-ROM19.

In the P-ROM 19, the numerical values of N corresponding to the addresses designated by the outputs of the address selection circuit consisting of the connection pipe diameter encoding circuit 30, the orifice type encoding circuit 31, and the steam pressure encoding circuit 32 are recorded as data. has been done.

When measuring the weight flow rate, if we ignore the instrumental error of the flow transmitter based on manufacturing errors of each part,
Even if the diameter D of the straight tube housing 5 and the opening ratio ψ of the orifice 4 are different, the other members are common and their specifications are fixed, so the meter constant k in equation (2) is the above D1ψ. The steam density r is determined by the steam pressure P. Thus, as shown as an example, each of the encoding circuits 30, 31 and 32 is connected to four switches 30-1 to 30-4, one switch 31-1 and five switches 32. -1 to 3
2-5, and resistors inserted in series with each of them, and each code is as shown in Table 1.
It is possible to define as shown in Tables 2 and 3.

Therefore, the meter constant KCkg+・m+ of the flowmeter is indicated by the 5-bit code Klk2k3k,k, which is a combination of the straight pipe diameter code and the orifice opening ratio code.
The corresponding numerical value A and the vapor pressure code K6k7k8k9k
Square root of saturated vapor density r under pressure corresponding to O VYCk
g+・m−÷], and their product A−
B always has a 4-digit integer part N, and the frequency division ratio of the second frequency divider, which will be described later, is 30, and the frequency division ratio of the auxiliary frequency divider (h )゛・(2)
, and set this 4-digit decimal integer N as a binary coded or binary coded decimal number, P-RO
It is stored in the corresponding address of M19.

Thus, the second frequency divider 21 is for compensating for the deviation of the meter constant k from the reference value based on the manufacturing error of each component of the flow transmitter 1.

The frequency division ratio of the second frequency divider 21 is set by an M setting circuit that can set a three-digit decimal number -M.

Therefore, for the value of M, the meter constant k is the reference value K. If the value A. is equal to, for example, exactly 500, then the numerical value A. ．． B. ．． N. ．． Therefore, if there is an error Δk in k and it is found that Settings are made using setting circuits 33, 34 and 35.

The auxiliary frequency dividers 22, 23 and the changeover switch 27 are used to shift the scale of the electromagnetic counter 29, and T
The bistable elements 24, 25, 26 and the changeover switch 28 are used to make the effective number of the set value N of the P-ROM 19 as large as possible, and to obtain the highest possible resolution.

Since the present invention is configured as described above, when according to the present invention, the receiver consisting of the circuits after the preamplifier 17 can be used in common regardless of the diameter of the flow transmitter and the orifice opening ratio l. Once the meter constant k of the flow rate transmitter 1 is known, when the orifice is replaced and its opening ratio is changed, simply switch 31-1, and when the steam pressure to be used is changed, switch 32 -1 to 3
Measurement accuracy can be easily maintained by simply switching 2--5.

Note that the configuration of the present invention is not limited to the above-mentioned embodiments; for example, although a flow rate transmitter is shown here for use in vertical piping running from below to above, it may also be applied to vertical piping running from above to below. It can also be applied to known flow rate transmitters used in horizontal piping, and the first and second frequency dividers can be configured by combining ICs known as #14527. Front, 10T
1 is shown, but there are also those with a frequency division ratio of -N7-Y7, and even 7゜7N. M. Generally, the frequency division ratio is C. ．． Let C'' be a constant.

．． ．． 05, the coding circuit 32 can be configured to be controlled by an appropriate digital pressure gauge, etc. The method of setting M, the configuration of the encoding circuit, etc. can be freely changed within the scope of the purpose of the present invention, and the present invention encompasses all of them.

[Brief explanation of drawings]

The drawing is an explanatory view showing one embodiment of a steam flow meter according to the present invention. 1...Flow rate transmitter, 4...Orifice,
5... Straight pipe section casing, 7... Measuring turbine chamber casing, 9... Nozzle plate, 10... Braking turbine chamber casing, 12... Metering Turbine, 13...
... Braking turbine, 14 ... Rotating main shaft, 1
5... Magnet, 16... Magnetic sensor, 1
7...Preamplifier, 18...Input pulse waveform shaping circuit, 19...P-ROMl2O.
・First frequency divider, 21...Second frequency divider, 29...
...Electromagnetic counter, 30... Connection pipe diameter coding circuit, 31... Orifice type coding circuit, 32...
...Coding circuit for vapor density, etc., 33, 34, 35
...M setting circuit.

Claims (1)

[Scope of Claims] 1. A pipe joint that can be connected to a transport pipeline for steam or gas to be measured (hereinafter referred to as steam, etc.), which is connected to the pipe joint,
and a housing having a straight pipe portion in the middle into which an orifice with an appropriate opening ratio is inserted, a side passage including a metering turbine chamber, and a braking turbine chamber provided isolated below the metering turbine chamber; A metering turbine provided in the turbine chamber, a nozzle provided at the inlet of the metering turbine chamber for injecting and rotating steam flowing through a side path to the metering turbine, and a rotary main shaft provided in the brake turbine chamber and penetrating the partition wall. a braking turbine coupled to a metering turbine;
A brake fluid injected into the brake turbine chamber, a pulse transmitter that detects the rotation of the rotating main shaft and transmits pulses, and counts the pulses and performs necessary correction calculations according to the density of the steam, etc. to be measured. A steam flow meter comprising a counter for displaying the weight and/or volumetric flow rate of passed steam, etc., wherein the counter comprises the circuits described in (a) to (g) below. (a) Input pulse waveform shaping circuit. (b) P-ROM (c) A coding circuit for the connecting pipe diameter, a coding circuit for the type of orifice to be used, and a code for the density of the steam, etc. to be measured, or the physical quantity that determines the density or is determined by the density. An address selection circuit for the P-ROM, comprising a conversion circuit. (d) Numerical value N determined by the output data of the above P-ROM
a first frequency divider whose frequency division ratio N/C is determined by and constant C; (e) A second frequency divider whose frequency division ratio M/C' is determined by a manually set numerical value M and a constant C'. (f) Pulse counter (g) A circuit in which the first frequency divider and the second frequency divider are connected in series in an appropriate order between the input pulse waveform shaping circuit and the pulse counter. 2. The address selection circuit is a connection pipe diameter coding circuit,
A steam flow meter according to claim 1, comprising an orifice opening ratio encoding circuit and a metered steam pressure encoding circuit.