SU947684A1 - Sampling device - Google Patents

Description

(54) SAMPLING DEVICE

The invention relates to automatic sampling devices for sampling gas from a stream and can be used as part of an automated process control system for automating production in the chemical, petrochemical and other sectors of the national economy.

A device for automatic sampling of gas from a stream is known, comprising a pneumatic pulse generator, a pulse metering device, a sampler, a carrier gas flow controller, a gas mixture flow regulator, a choke divider. The device periodically takes a portion of the sample, dilutes it with an inert gas and, through the mixture flow controller, supplies the sample for analysis 11.

The disadvantage of the device is its complexity, low reliability, high accuracy requirements. Generator work.

An automatic sampling device is known that contains a mixing collector, two throttles installed on the lines of an inert gas and a diluted sample, an amplifier, an ejector 2.. .

The device maintains equal pressure drops at both throttles ,.

which provides a relatively accurate degree of dilution of the test gas inert. In this case, before the throttle installed in the inert gas line, the pressure is maintained by the amplifier twice as large as before the dm throttle.

Studies of this device showed that, when the pressure of the gas being analyzed changes, the dilution accuracy is the lower, the wider the range of pressure changes.

The purpose of the invention is to improve the accuracy of sampling.

Claims (2)

The goal is achieved by the fact that the device containing a mixing manifold, a throttle installed in the inert gas line, an amplifier connected to the inlet and outlet respectively with the output and inlet throttle inlet gas, the ejector, is equipped with a pressure stabilizer and a mixer, the outputs of which are supplied with throttles, connected to the mixing manifold, a pressure stabilizer, and an ejector inlet, while the internal cavity of the mixer is connected to the atmosphere. FIG. 1 shows a circuit diagram of the device in FIG. 2 is a graph of flow versus pressure. The device consists of a pneumatic amplifier 1, an ejector 2, throttles 3, a mixing manifold 4, a mixture of bodies 5, a pressure stabilizer 6. In the mixer 5 installed chokes 8 and 9. The device operates as follows. The analyzed gas from the 10 riojct apparatus enters its own pressure into the collector 4, where it mixes with the inert gas through the throttle 3. The pressure in the collector 4 along the route 11 is fed to the input of the amplifier 1, at the outlet of which up to throttle 3 is maintained the input of the amplifier 1. The gas from the manifold, 4 through the choke 9 enters the mixer 5. Into the inert gas from the stabilizer through the choke 8 b. Atmospheric pressure is always kept in the mixer. The mixture from mixer 5 is sucked into the ejector 2, from where it enters the analyzer 12. Thus, a three-stage dilution occurs in the device: in the collector 4, in the mixer 5 and in the ejector 2. When the inert gas flow stabilizes through the ejector and the pressure stabilizes on stabilizer output b accuracy of dilution depends on the ratio of gas flow through the inductors 3 and 9. At the throttle 9, the differential is equal to the pressure in the apparatus 10. At the input of the throttles 3 the pressure is twice as large as in the collector 4, therefore the differential at throttle 3 is equal to the differential at throttle 9. But since the flow through the choke depends not only on the differential, but also on the absolute pressure at its inlet, when the pressure in the apparatus 10 changes, the flow through the inductors 3 and 9 change disproportionately. In the drawing, expenses G are indicated through a choke 3, G is the flow rate of the gas being analyzed, Gj is the flow through choke 9, 64 is the flow through the choke 8. Studies have shown that the dependence of the flow rates G j and (C on pressure in apparatus 10 is non-linear. In the range of pressure from P to RP, the flow curves can be approximated directly and € g. From the drawing it can be seen that e and e intersect at point Q below the pressure axis. As a result, the ratio G / G is different at each point of the pressure range from P to Pij. To keep this attitude constant To transfer the origin of coordinates from point O to point I. This is achieved by adding a constant flow rate G to the flow rate G .. The flow rate G in the sampling scheme is introduced into the mixture through the choke 8. In so doing, consider the ratio (G + G) / G (j, which does not depend on the pressure in the apparatus 10. The dilution error now depends only on the inaccuracy of the approximation of the G and G curves of the straight lines R. Laboratory testing of the proposed dilution sampling device showed that when the pressure changes from 0.2 to 0.8 kgf / cm dilution decreased d about 1% with a ratio (G + Gj) / G4 equal to 5 i. Previously, this ratio changed from 5.3 to 4.6. Claims: Sampling device containing displacement collector, choke, installed on inert gas line, amplifier connected to inlet and outlet, respectively, with inlet gas inlet throttle outlet and inlet, ejector, characterized in that it is equipped with a pressure stabilizer to improve sampling accuracy and a mixer, whose people are equipped with throttles and are connected to a mixing manifold, a pressure stabilizer and an ejector inlet, while the internal cavity of the mixer is connected to the atmosphere. Sources of information taken into account in the examination 1. USSR author's certificate number 453606, cl. G 01 N 1/22, 1973. 2. Authors certificate of the USSR 581417, cl. G 01 N 1/22, 1976.