BRIEF INFORMATION ON LIQUID AND GAS FLOW METERING

Substantiation of new developments in flow metering sphere
The overwhelming majority of meters and flowmeters used in the oil and gas industry has been represented for more than one hundred years by the instruments where a jump of pressure in a constriction device serves as a basic value being measured (the so called diaphragm instruments). It’s no doubt that the US “Superflow-2” is now the most advanced instrument of this type. This flowmeter has had no chance to become the principal one in such countries as Ukraine, Russia etc. due to its high cost (it’s price is about U.S. $15000). Therefore, the national instruments operating on the same principle have been developed in many countries. The “Flowtech” and “Flowcore” flowmeters produced in Kiev are among the most popular ones in Ukraine. These instruments are twice cheaper than “Superflow-2” (due to a worse quality, of course). It may be noted right here at the assembly of a diaphragm instrument costs at least U.S. $1500 —$2000. It’s natural that diaphragm instruments were chosen by impressive reasons. One of such reasons is expressed by the fact that recalculation of pressure jumps to flow rates is based on simple fundamental laws of hydro- and gas dynamics. Hence, theoretical calibration of instruments can be quite used in practice which cannot be said about any other flowmeter belonging to a different system. During the time when reliable calibration benches did not practically exist nobody even tried to find an alternative. Nowadays, reliable calibration benches have been developed in all gas- and oil production countries, as well as the countries engaged in transportation and storage of gas (including Ukraine). Thus, diaphragm flowmeters are gradually losing the advantage of theoretical calibration practical use. Moreover, it were full-size benches that helped to find out that diaphragm flowmeters lost fast their metrological characteristics in respect of dirty gas or liquid. In particular, diaphragm instruments cannot be used for measurement of flow rates in well mouths, as well as in gas underground stores. One of the reasons of this situation is the loss of metrological characteristics, while the other reason is a high aerodynamic resistance generated by diaphragms. There are two more cases when diaphragm instruments cannot be used: 1) conditions of low flow rates; 2) large diameters of pipelines. Particularly, diaphragm flowmeters cannot be used for measurements of flare gas flow rates.
Considering the above it becomes clear why new flowmeters running on the principles based on different physical phenomena are under development in many countries (thermal, electromagnetic, acoustic, optical and other flowmeters). Thermal flowmeters based on the principles of heat take off from thermal probes, as well as ultrasonic flowmeters based on the measurement of deviations of ultrasonic waves by moving flows belong to the most promising ones.

Family of «Cyclone-1», «Cyclone-2», «Cyclone-2M» flowmeters
The «Cyclone» family has been developed by the scientists and engineers of the «Cyclone» Measurement Equipment Institute”, Kharkov. The flowmeters of «Cyclone» type possess considerable advantages over thermal flowmeters that were produced in Germany and Russia. The principal advantage is that the working chamber accommodating a thermal probe (thermal transducer) communicates with the main flow via a so called “flow divider”; the flow divider reduces the main flow to create a flow being proportional to the main flow but having a lower speed (in any controlled number of times). In addition, the flow divider acts as a filter and, therefore, the «Cyclones» can be installed both in mouth wells and in underground gas stores. The early «Cyclones» were developed more than 10 years ago and were not admired by supporters of diaphragm flowmeters. During the last 10 years the «Cyclones» have been improved, the remarks of operation organizations being taken into account. At present, «Cyclone-2M» is the most advanced one (in all respects). «Cyclone-2M» can measure any flow rates (practically from zero and up to tens million m3/hour). Pipeline internal diameters, on a larger side, are not limited with the lower limit making 100 mm. All «Cyclone» instruments are protected by patents, as well as have been made a part of the state registers of Ukraine and Russia. It’s extremely important that «Cyclone-2M» is the sixteen-channel instrument, i.e. one instrument can measure flow rates in parallel in sixteen pipelines (or in any less number of pipelines). This makes the flowmeter much cheaper than any other flowmeters.
«Cyclone-2» operated with success in the “Kharkovtransgas”, “Kharkovgasdobycha”, “Poltavatransgas”, “Poltavagasdobycha” “Lvovtransgas”, “Severgasprom” (Russia) and many other enterprises.
«Cyclone-2M» underwent the State Tests at air test benches and showed a relative error of 1 %. Besides, a relative error of 2 % was shown as a result of full-size tests in Ivano-Frankovsk.
«Cyclone-2M» underwent long-term tests carried out by the “Lvovtrangas” enterprise in the underground gas stores (under conditions of a very dirty gas) where the 3 % relative error was demonstrated. Neither instruments that had been used earlier under similar conditions showed such results (normally, 6-10%).
During the period of 7 months «Cyclone-2M» underwent the tests at the Akhtyrka Oil-and-Gas Department for measurement of flare gas flow rates. It was admitted by the management of this enterprise that «Cyclone-2M» is above competition as far as flare gas measurements are concerned. The previous modifications of the «Cyclone-2» instrument stood the tests under conditions of extreme north and subtropics (Brasilia).

PHYSICAL PRINCIPLES OF «CYCLONE-2M» OPERATION

Welded in the wall of pipe 5 is boss 4 having a threaded hole provided therein to fasten flow divider 3. Provided inside the flow divider is a transducer 2, including thermal resistor 1 and active thermal resistance 7.
The pressure in shadow zone T is higher than the pressure on the tip of the lens which makes the end face of the flow divider by the value of the medium dynamic pressure in the lens tip zone which is located at the distance of 0.242 R (where the local velocity is equal to the section average velocity, R is the pipeline radius).
On account of this pressure distance the measurement medium passes between the transducer outer surface and flow divider inner surface. In this case, the medium washes about the transducer casing portion being connected with the thermal resistor (via compound). The higher is the washing about velocity, i.e. the flow rate the faster the preheated resistor gives away heat (cools down) as a result of it. The gas (liquid) velocity inside the flow divider is lower than the velocity of flow inside the main pipe. In this case, the reduction coefficient can be controlled to vary over a wide range (from 10 to 106) with the help of holes provided in the flow divider. The thermal probe cooling down rate serves as the major source of flow rate data.

ADVANTAGES OVER FLOWMETERS OF OTHER SYSTEMS

• multiple channels;
• wide range of measured flow rates;
• measurements are made with pipeline capacities being maintained;
• no moving elements in the flow;
• convenient and fast assembly and disassembly;
• lower prices.