JPS6411130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that detects pressures at two different heights in a liquid and measures the density (specific gravity) of the liquid based on the differential pressure. The present invention relates to a density measuring device suitable for use in density measurement.

Generally, one method of determining the specific gravity of a liquid in a liquid tank is to detect pressures at two positions at different heights in the liquid and obtain the pressure difference. On the other hand, there are various methods for detecting the pressure at the position of the liquid, that is, the differential pressure, but the most common and cost-effective method is a diaphragm seal differential pressure gauge that uses silicone oil as the pressure transmission medium. be.

However, with such a diaphragm differential pressure gauge, there is a problem in measuring high temperature liquid over a long period of time. In other words, if the temperature of the liquid to be measured exceeds 200°C, the silicone oil sealed in the diaphragm as a pressure transmission medium will gradually deteriorate, making it impossible to accurately transmit differential pressure over a long period of time. There is a problem. This is because the silicone oil is heated through the pressure measuring diaphragm, which causes changes in specific gravity, vapor pressure, etc., and these changes cause errors in the differential pressure gauge.

The present invention was developed in view of the above circumstances, and has an extremely simple configuration in which a gas storage chamber consisting of a rising portion is provided at two pressure outlets provided on the side wall of the liquid tank, and the high temperature inside the liquid tank can be reduced. The present invention provides a density measuring device that can stably measure liquid over a long period of time. Hereinafter, its configuration and the like will be explained in detail using an example shown in the drawings.

FIG. 1 is a longitudinal cross-sectional view showing a part of a liquid tank in which a density measuring device according to the present invention is installed. , this side wall 1 has 2 walls with different heights.
Two pressure outlets 3 and 4 are provided. That is, these two pressure outlets 3 and 4 are provided apart from each other by a predetermined distance h in the height direction. The pressure outlet ports 3 and 4 are
It has extension parts 3a and 4a extending laterally, and a gas storage chamber 5 is provided on the extension parts 3a and 4a.
Rising portions 3b and 4b are provided to form a . A differential pressure detection end 8 in which silicone oil 7 as a pressure transmission fluid is sealed in a pressure measuring diaphragm 6 is attached to the upper open end of the rising portions 3b, 4b. The differential pressure detection ends 8, 8 are connected to the differential pressure gauge main body 9 via a capillary 10.
connected to each diaphragm chamber. Reference numeral 11 denotes a gas collecting member extending inside the pressure outlet ports 3 and 4, and this member 11 is formed of a semi-cylindrical member opening downward as shown in FIG.

Reference numeral 12 indicates a liquid supply port, and reference numeral 13 indicates a gas purge port, which are provided at a location directly below the pressure outlet 4.

Since the apparatus of the present invention is configured as described above, the gas contained in the supplied liquid 2 in the liquid tank is
The gas storage chamber 5 is trapped by the gas collection member 11.
It will accumulate inside. Therefore, the pressure at the pressure outlet ports 3 and 4 acts on the pressure measuring diaphragm 6 via the gas in the gas storage chamber 5. Therefore, the pressure measuring diaphragm 6 does not come into direct contact with the liquid to be measured 2, and the heat transfer path of the liquid to be measured 2 to the detection end 8 for taking out the differential pressure is mainly through the annular rising portions 3b and 4b. , and the heat dissipation effect by the rising portions 3b and 4b can prevent the silicone oil 7 from increasing in temperature.
That is, the convection transfer by the gas in the gas storage chamber 5 is extremely low compared to the heat transfer in the rising portions 3b, 4b, and therefore the length l of the rising portions 3b, 4b is
By increasing the length, the surface temperature of the diaphragm 6 can be reduced to a temperature that does not affect the silicone oil, for example, by only atmospheric heat radiation from the outer peripheral surfaces of the rising portions 3b and 4b.
Can be kept below 200℃.

By the way, since the liquid to be measured generally contains bubbles, a necessary amount of gas can be collected in the gas storage chamber 5 within a short period of time. As described above, when the liquid to be measured contains bubbles, it is desirable to provide the liquid supply port 12 below the pressure outlet 4 as in the above embodiment. On the other hand, if there is no such liquid supply port 12, when the liquid to be measured contains almost no air bubbles, or within a short time, the gas storage chamber 5
When it is desired to store gas, it is sufficient to open the on-off valve 15 and supply the inert gas 16 into the liquid from the gas purge port 13.

Next, to describe the density measurement of liquid with the above configuration, the gas collection member 1 of each pressure outlet 3, 4 will be described.
Since the head pressure from the liquid level of the liquid tank is applied to the liquid level of 1 and 11, each diaphragm 6 and 6 is
are subjected to their respective head pressures. The diaphragms 6, 6 used as pressure sensors are made of metal or non-metal materials (e.g. DSTJ),
The pressures at the upper and lower outlets 3 and 4 are measured as a differential pressure ΔP, and the density γ can be calculated from the equation γ=Δh/h from this differential pressure ΔP and a preset constant value h.

If the liquid level in the liquid tank fluctuates, for example, rises, the head pressure will increase, so the liquid level in the gas collecting members 11, 11 will also rise, and the liquid level in the upper and lower gas collecting members 11, 11 will increase. Since the numbers are different, h is
h′, and the density γ cannot be measured accurately.

In contrast, the present invention provides each gas collection member 11,
11 is attached directly above the liquid supply port 12 and its shape is opened downward so that gas can be easily and reliably collected. The liquid level in the gas collecting members 11, 11 is always kept constant even if the liquid level in the liquid tank fluctuates, and the gas purge hole 13 is also provided in case the air bubbles in the inflowing liquid alone are not sufficient for replenishment. is prepared, which makes it possible to measure the density γ.

In addition, the dimensions of the gas collection member 11 and the diaphragm 6 are set relatively large, and as a measure against high temperatures,
Since the dimensions are introduced, the volume of the gas storage chambers 5, 5 is large, and therefore, the liquid level in the gas collecting members 11, 11 does not change greatly even when the liquid level in the liquid tank changes. .

Therefore, for this reason, the influence on h, which is the difference between the liquid levels in the upper and lower gas collecting members 11, 11, is also reduced.

On the other hand, if the volume of the gas storage chambers 5, 5 is small, the liquid level in the gas collecting members 11, 11 will fluctuate greatly due to the liquid level fluctuation in the liquid tank, resulting in pressure loss and Although accurate pressure may not be transmitted, in the present invention, as described above, each pressure outlet 3, 4 is provided with rising portions 3b, 4b, respectively, to increase the volume, so there is no need to worry about this.

As explained above, according to the present invention, the liquid is prevented from coming into direct contact with the pressure measuring diaphragm of the differential pressure gauge by using air bubbles in the high-temperature liquid or by supplying gas into the liquid. , it is possible to perform stable density measurements over a long period of time without changing the quality of the diaphragm-sealed pressure transmission fluid. Another advantage is that relatively inexpensive silicone oil can be used as the pressure transmission fluid because the pressure transmission fluid is not heated to high temperatures. Furthermore, since the liquid to be measured does not come into contact with the diaphragm, the liquid does not adhere to or solidify on the diaphragm surface, and the sensitivity of the diaphragm can be maintained constant.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a density measuring device according to the present invention, and FIG. 2 is a cross-sectional view. 1... Side wall, 2... Liquid to be measured, 3, 4... Pressure outlet, 3b, 4b... Rising part, 5... Gas storage chamber, 8... Differential pressure extraction detection end, 13... Gas purge mouth.

Claims (1)

[Scope of Claims] 1. Two pressure outlets having different heights are provided in the side wall of the liquid tank, and a rising portion forming a gas storage chamber is provided above each pressure outlet, and the inner part of the outlet is provided with a rising part forming a gas storage chamber. A downwardly-opening gas collecting member protruding into the liquid tank is extended at each end, and a differential pressure extraction detection end is provided in which a pressure measuring diaphragm faces the gas storage chamber and a pressure transmitting liquid is sealed. Features: Density measurement device for high-temperature liquids. 2. Two pressure outlets are provided at different heights on the side wall of the liquid tank, and a rising part forming a gas storage chamber is provided above each of these outlets, and a pressure outlet is provided inside the liquid tank at the inner end of the outlet. Protruding downward-opening gas collection members are each extended, and a differential pressure extraction detection end in which a pressure measurement diaphragm faces the gas storage chamber and pressure transmission fluid is sealed is provided, and a gas collection member is provided directly below the pressure extraction port. A high temperature liquid density measuring device characterized by being equipped with a purge port.