RU2601615C1 - Method for determining volume of non-tight tank - Google Patents

Abstract

FIELD: measurement technology.

SUBSTANCE: use: determining volume of large-size non-tight tanks in the aerospace, nuclear, petrochemical, food and mining industries. Method for determining volume of non-tight tank involves increasing pressure in tested tank, disconnection of pressure source, recording of pressure variation during time. Wherein high pressure gas is supplied into the tank with simultaneous measurement of time of gas supply through gas flow meter, measurement of temperature change by means of temperature sensor. Then, gas supply is switched off and time of recovery of pressure and temperature to initial values are measured, and volume of non-tight tank is determined by formula: $$V_0=\frac{Q_{\sup }}{\left(\frac{p_1}{R{T}_1}-\frac{p_0}{R{T}_0}\right)}\frac{t_2}{t_1+t_2},$$

where Q_sup is weight of gas pumped through meter, t₁, t₂ - time of variation of parameters (pressure, temperature) in tested tank, T₀ and T₁ - temperature in the tank before and after supply of gas, respectively, p₀ and p₁ - pressure in the tank before and after supply of gas, respectively, R - gas constant (specific).

EFFECT: technical result is high accuracy of determining volume of non-tight tank.

1 cl, 1 dwg

Description

The invention relates to measuring equipment, in particular to determining the volume of large-sized leaky containers in the aerospace, nuclear, petrochemical, food and mining industries.

There is a method of determining the volume of an unpressurized gas-filled container (Pat. RU No. 2018790, IPC: G01F 17/00, publ: 08/30/1994), in which a fixed amount of P _g · V _{g of} indicator gas is introduced into a controlled container, pressure Ρ of the mixture, concentration are measured it contains indicator gas and processes the measurement results, characterized in that, in order to improve accuracy by performing measurements in a homogeneous medium, the gas is continuously mixed in the container before the indicator gas is introduced and during the entire determination process, before the indicator is introduced -gas concentration is measured in its background capacitance C _p, C _m largest lower limit indication indicative measurement means and a predetermined volume V indicative controlled capacitance determined fixed amount of tracer gas, corresponding to the relation

where Ρ _g - absolute pressure of the tracer gas;

V _g - indicator gas volume at absolute pressure R _g ,

after the start of the introduction of the indicator gas into the controlled vessel, its concentration is continuously measured and measurements are continued after the end of the introduction until the concentration level is 0.7-0.8 of its maximum calculated value corresponding to the conditions for instant introduction into the volume V of the entire amount of the indicator gas without loss, and when processing the measurement results are capacitance value of the volume V from the expression _EMK

The disadvantages of this method include the difficulty of introducing into the test tank a fixed amount of indicator gas with continuous mixing of gas in the tank, measuring the background concentration of the indicator gas in the tank, the amount of the indicator is determined by the value of the lower limit of the indication that characterizes the measuring instrument, and the approximate volume of the tank gas, calculate the maximum value of the concentration corresponding to the conditions of instant introduction into the volume of the total number of indicators iterated gas without losses, and the volume capacity is determined from a mathematical expression.

The closest in technical essence and the achieved result to the claimed method is known for determining the volume of an unpressurized tank with a laminar nature of the outflow of gas from it (Pat. Ru No. 2026533, IPC: G01F 17/00, publ.: 09/01/1995), including the creation of excess pressure in it with the subsequent shutdown of the pressure source, recording the pressure change over time in the leaky tank and determining the volume of the leaky tank, characterized in that they calculate the time constant of the leaky tank, then connect the leaky tank the reference vessel, observing the conditions of free flow of gas between them, create an overpressure in the system formed from an unpressurized and reference vessel and then turn off the pressure source, record the pressure change in the formed system, on the basis of which the time constant of the formed system is calculated, and the volume determination is leaky capacities are produced by the computational values of the time constants of the leaky capacitance and the formed system and by the volume of the reference capacitance.

The disadvantage of this method is the large consumption of materials, the complexity associated with the need to use a reference tank, as well as ensuring the laminar flow of gas from tank to tank, and failure to fulfill the latter condition leads to a significant error.

The objective of the invention is to reduce material consumption, simplifying the method of determining the volume of leaky capacity.

The technical result is an increase in the accuracy of determining the volume of leaky capacity.

The problem is solved, and the technical result is achieved by the method of determining the volume of an unpressurized container, which consists in increasing the pressure in the test container, followed by turning off the pressure source, recording the pressure change in time, in which according to the invention the pressure is increased by supplying gas to the container with simultaneous measurement of time gas supply through a gas flow meter, measuring the temperature change by means of a temperature sensor, then turn off the gas supply and measure the time the formation of pressure and temperature to the initial values, and the volume of the leaky tank is determined by the formula:

where Q _Zack - the volume of injected gas through the meter,

t ₁ , t ₂ - time changes in the parameters (pressure, temperature) in the test tank,

T ₀ and T ₁ - temperature in the tank before and after gas injection, respectively,

p ₀ and p ₁ - pressure in the tank before and after gas injection, respectively,

R is the gas constant (specific).

The invention is illustrated in the drawing, which shows a diagram for determining the volume of leaky containers.

An example of a specific implementation of the method

The circuit for determining the volume of an unpressurized container contains a container of a determined volume 1, a pressure source (in this case, a compressor) 2, a receiver 3, a gas flow meter 4, a pressure gauge 5, and a thermometer 6.

Gas is pumped into the leaky tank 1, for example, air through a compressor 2 through a receiver 3 and a meter 4 with a mass Q _zak , as a result of which the pressure in the tank 1, measured by a pressure gauge 5, increases from p ₀ to p ₁ , and the temperature measured by a thermometer 6, from T ₀ to T ₁ , at time t ₁ . Then the injection is stopped, the time t ₂ of pressure reduction from the value of p ₁ to p ₀ , the temperature from T ₁ to T _{0 is} measured. If q _ut is the average leakage value from an unpressurized container (kg / s), then

where m ₀ is the initial mass of gas in the tank,

T ₀ and T ₁ - temperature in the tank before and after gas injection, respectively,

R is the gas constant (specific).

Expressing q _уm from equations (2) and (3) (we assume that the leakage rate during and after gas injection remains constant) and equating the obtained expressions, we obtain:

from (2):

from (3):

Equate:

We collect:

Solving the system, we find the volume of the leaky capacity

So, the claimed invention allows to reduce the consumption of materials, to increase the accuracy of determining the volume of leaky capacity.

Claims (1)

A method for determining the volume of an unpressurized tank, which consists in increasing the pressure in the test tank, turning off the pressure source, recording the pressure change in time, characterized in that the pressure is increased by supplying gas to the tank while measuring the time of gas supply through the gas flow meter, measuring the temperature change by means of a sensor temperature, then turn off the gas supply and measure the time of restoration of pressure and temperature to the original values, and the volume of the leaky tank predelyayut by the formula:
$$V_0=\frac{Q_{s\mathrm{but}\mathrm{to}}}{\left(\frac{p_{\mathrm{one}}}{R{T}_{\mathrm{one}}}-\frac{p_0}{R{T}_0}\right)}\frac{t_2}{t_{\mathrm{one}}+t_2}$$

where Q _Zack - the mass of the injected gas through the meter;
t ₁ , t ₂ - time changes in the parameters (pressure, temperature) in the test tank,
T ₀ and T ₁ - temperature in the tank before and after gas injection, respectively,
p ₀ and p ₁ - pressure in the tank before and after gas injection, respectively,
R is the gas constant (specific).

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