SU787747A1 - Apparatus for determining heat resistance of substance - Google Patents

Description

one

The invention relates to devices for the analytical control of the thermal stability of a substance and can be used in the chemical, metallurgical industry and other branches of the national economy.

A device for determining the pressure of the flowing medium is known, comprising a housing with a flexible membrane dividing it into two chambers, in the center of one of which is an output channel, the flow of the flowing medium into which is controlled by the membrane (1.

The closest to the invention in its technical essence is a device for determining the thermal stability of a substance, comprising a housing with a membrane installed in it, dividing the housing into the measuring H deaf chamber and associated with the zero setting mechanism, a reaction vial connected to the housing deaf chamber by means of an assembly seals and repair device 2.

The disadvantage of this device is a high error, which depends on the range of the parameter, and, consequently, the greater, the wider the range.

The purpose of the invention is to improve the accuracy of parameter measurement while expanding the range of its values by reducing the absolute error.

This goal is achieved by the fact that the device is equipped with an adder, pneumatic resistances and a nozzle installed in the measuring chamber and separating it into two cavities connected to the first and second inputs of the adder, the first input of the adder through the pneumatic resistance and exit

10 an adder is connected via a pneumatic resistance to the recording device.

FIG. Figure 1 shows a diagram of a device for determining the thermal stability of a substance with a single membrane and a local mechanism for setting zero; in fig. 2 - the same, with two membranes and with a remote zero setting mechanism.

A device for determining the thermal stability of a substance consists of a reaction 20 glass 1, a membrane 2, a measuring chamber 3, a seal assembly made in the form of a socket 4, a protrusion 5 of a reaction glass I, a sealing element 6, which is acted upon by a sealing force created by a nut ( not shown in the drawing), nozzles 7. a cavity 8 of the measuring chamber, pneumatic resistances 9-12, an adder 13, a recording device 14. A local zero setting mechanism contains a string 15, a spring 16, an adjusting screw 17 (Fig. 1). The remote zero setting mechanism comprises a second membrane 18, rigidly connected to the membrane 2 (of larger diameter), forming a chamber 19 connected to the pressure setting device 20 (Fig. 2).

The device works as follows.

The device is put into operation by supplying the supply pressure through pneumatic resistance 12. The zero is adjusted using a screw 17, which through the spring 16 and the string 15 creates a force upward and corresponding to a zero value. At the same time, the nozzle 7 is covered and in the measuring chamber 3 the pressure rises, which balances the applied force generated by the screw 17. The pressure from the measuring chamber 3 flows to the adder 13 and through the pneumatic resistances 10 and 11 to the recording device 14, whose readings correspond to zero (initial ) value.

The analyte is placed in the reaction vessel 1., which is placed in the socket 4. When creating the sealing force, the reaction vessel 1 is sealed and placed in a thermostat (not shown in the drawing).

Under the influence of temperature, the analyte decomposes and the pressure in the reaction glass 1 changes. The membrane 2 bends, for example upwards, closes the nozzle 7, and the pressure in the measuring chamber 3 increases to a equilibrium state when the pressure in the reaction glass 1 is equal to the pressure in the measuring chamber 3 taking into account Zero and error settings. The magnitude of the error is determined by the cavity 8 of the measuring chamber, since in the new equilibrium state the research institute membrane 2 assumes a new position, and the gap between the membrane 2 and the nozzle 7 changes, causing a proportional change in pressure of the cavity 8 of the measuring chamber. The signals from chamber 3 of cavity 8 are fed to an adder 13, where the measurement error is compensated. However, the adder 13 operates in the entire measured interval (range) and, therefore, introduces its appreciable error. To reduce the error of the adder 13, signals from camera 3 and from adder 13 through pneumatic pulses (chokes) 10 and 11 are fed to a recording device 14. Thermal stability of the analyte is judged by the change in the output signal over time.

When using two membranes and a remote zero setting mechanism in the device, the work is carried out as follows (Fig. 2).

The device is put into operation by supplying pressure through pneumatic resistance 12. Remote zero setting is performed using pressure setting device 20, which is connected to chamber 19. Since membrane diameter 2 is larger than membrane diameter 18 and membranes are connected by a rigid center, the force action from pressure will be sent up. Further, the operation of the device does not differ from the operation of the device shown in FIG. one

The reduction in absolute measurement error of pressure is accomplished by additionally determining the current value of the measurement error (conversion) and compensating for it by summing the additionally measured error signal and the output signal in which this error occurs.

To determine the error of the measuring chamber 3, there is a cavity 8 of the measuring chamber 3. The magnitude of this signal is formed either pre-selected (constant) or adjusted by adjustable pneumatic resistance 9. To compensate for the errors, the signal of the measuring chamber 3 and the cavity 8 of the measuring chamber 3 are summed. 8 by means of the adder 13 is shifted to the region of the signal value of the measuring chamber 3, and then only a part of the signal is taken from the output signal of the adder 13 for correction. This makes it possible to significantly reduce the error of the adder 13, as can be seen from the following expression.

Y X ± yХ (1 - К) ± Д (1 - К), where Y is the output signal;

X signal in chamber 3; X Р ± Xi, Р - input signal (zero pressure);

X (-sign of signal P in the chamber 3.

Then we get: Y Р ± Х, ± ЛХ (1 -К) ± Л (1-К). .

Through adjustable throttle 9 adjust the value of LH so that Xi-LH (1 - K).

Then we get Y P + D (1 - K).

For example, when K is 0.9, we get P ± 0.1D.

The expected economic effect according to preliminary calculations is 12 thousand rubles. per year for one automatic installation of the control of the substance resistance (AUKS).

Claims (2)

1. US Patent No. 3612085, cl. 137-12, published. 1971. 2. USSR author's certificate No. 546742, cl. F 15 C 3/04, 8.08.74 (prototype).