SU1161826A1 - Heat flowmeter - Google Patents

Abstract

A HEAT FLOWMETER, containing a current pulse generator, heating elements and thermal receivers, a measuring complex, characterized in that, in order to improve the measurement accuracy, heating elements and thermal receivers are installed in a flow on surfaces coinciding with the axial cross section of the fixed pipeline pipeline at equal distances each from each other along its length, with each of the thermal receivers following its heater, being from it at the same fixed distance, the heating elements are Aligned on both sides of the board, made in the form of orthogonal -, -. narrow lanes connected to the pipeline axis and connected in parallel to common buses connected to a current pulse generator, thermal receivers form along the width of the board several parallel pipe axes of rows (channels) with a constant spacing between them and shifting the rows of one side of the board relative to There are half steps across the other side of the channel, each channel contains the same number of series-connected thermal receivers, the measuring complex contains a KAMAK-compliant timer, clock generator, circuitry control, crate controller, controllable timers, and S also microcomputers, photo reader, (L display and printing device, the output of each of the channels of thermal receivers is connected to the input of the corresponding controlled timer, the first output of the generator of clock pulses is connected to the second inputs of controlled timers, the second generator output. connected to a timer, controlled timers, clock generator, timer, control circuit and crate controller under Oi are connected to the CAMAC highway, the output of the control circuit is connected to the input of the current pulse generator, to the output of which the heating elements are connected, is connected to a microcomputer with a photo reader, a printing mechanism, a display and a crate controller, and the input of each of the controlled timers is the input of the operational amplifier, the output of which is connected to the first the comparator’s input directly, and with the second through the peak detector, you

Description

the comparator stroke is connected to the trigger start input, connected by its counting input to the first clock generator output, the second output of which is connected to the timer input, the comparator output is also connected to the trigger trigger input, the output of which is connected to the trigger input of the comparator The output of which is connected to the second input of the comparator, and the input of the delay and reset circuit, the output of which is connected to the input of the control circuit and to the installation input of the trigger.

The invention relates to instrumentation, namely, to heat metering meters, and can be used to determine the amount of pumped liquid in a stream, for example, oil through a main pipeline. Thermal marking pacx domers are known, the PRINCIPLE of action of which is based on the input of thermal energy into the flow from a pulsed heater, recording the energy state of the flow of a thermal receiver, located at a fixed distance from the radiator, and determining the average flow rate through the passage of this fixed distance thermal tag. Microwave or infrared sources are used as non-contact sources of heat labels. The registration of the passage of the tags is carried out using thermal resistors, capacitive measuring cells, ultrasonic oscillations. However, these devices are of low accuracy due to the fact that with the onset of heat movement in the flow, it is deformed (by the velocity field, thermal conductivity) | and approaches the thermal receiver in the form of a highly diffuse region. The closest in technical essence to the present invention is a flow meter that contains a generator of current pulses, heating elements and thermal receivers, as well as a measuring complex h. In this flow meter, the signal coming from the thermal receivers after preprocessing is continuously differentiated, and the equality of the derivative to zero corresponds to the moment of passing the label of the thermal receiver. However, with an increase in the diameter of the pipeline, the sensitivity of such a flow meter drops sharply due to the absence of signals, which are used to register tags, with a clearly defined maximum. In addition, the accuracy of flow measurement with this device is low due to the low intensity (heat transfer processes in the system moving the pipeline wall flow and the inability to take into account the real diagram of flow rates over the cross section. The purpose of the invention is to improve the accuracy. The goal is achieved containing a current pulse generator, heating elements and thermal receivers, a measuring complex, heating elements and thermal receivers installed in the flow on surfaces coinciding with the axial cross section of the pipeline of the fixed board at equal distances from each other along its length, each of the thermal receivers following its heater, being at the same fixed distance from it, the heating elements are located on both sides of the board, in the video, orthogonal to the axis of the pipeline, narrow bands and connected in parallel to the common buses connected to the current pulse generator, the thermal receivers form along the width of the board several parallel to the axis of the pipelines (channels) with constant th juaroM between them and shifted rows

one side of the board with respect to the rows of the other side in half a step, each channel contains the same number of series-connected thermal receivers, the measuring complex contains a timer made in the KAMAK standard, a clock pulse generator, a control-crate control circuit, controlled timers, and also a micro-computer, a photo reader, a display and a printing device, with the output of each of the channels of the thermal receivers connected to the input of the corresponding controlled timer, the first output of the clock pulse generator The second input of the generator is connected to the timer, the controlled timers, clock generator, timer, control circuit and the controller-controller are connected to the CAMAC trunk, the output of the control circuit is connected to the input of the current pulse generator, Heaters are connected to the output of the microcomputer connected to the photo reader, the printing mechanism, the display and the crate controller, and the input to each of the controlled timers is the input of the operational amplifier, the output of which is connected to the first input of the comparator directly, and to the second through a peak detector, the comparator output is connected to the start input of the counter connected to the first output of the clock generator, the second output of which is connected to the timer input, its output is also connected to the trigger input The output of which is connected to the trigger input of the comparator, the input of the discharge key, whose output is connected to the second input of the comparator, and the input of the delay and reset circuit, the output of which It is connected to the input of the control circuit and to the installation input of the trigger. I.

Figure 1 shows the board with heat

thermal elements and thermal receivers and its placement in the pipeline; figure 2 - block diagram of the measuring complex; Fig. 3 is a block diagram of a controlled timer; Fig. 4 is a schematic diagram according to the flow rate calculation algorithm (for a 5 cag flow meter).

Thermal receivers 1-5 (Fig. 1) and heaters 6 with tires 7 feeding them are located on board 8 fixed along the diametral plane of pipeline 9. Board 8 together with heaters 6 distributed over its length and thermal receivers 1-5 is a speed sensor 10 (FIG. 2). The edge of the board meeting the flow has a cross section profile that prevents disturbances of the fluid near the surface of the Speed sensor 10. Through the connector 11, the supply buses 7 are connected to the current pulse generator 12, and the outputs of the channels 1-5 to the inputs of the corresponding controlled timers 13. Each controllable timer 13 (FIG. 3) includes an operational amplifier 14, a peak detector 15, a bit switch 16, a comparator 17, a trigger 18, a counter 19, a delay and reset circuit 20. The output of each channel is connected to the input of the corresponding operational amplifier 14, the output of which is connected to the first input of the comparator 17 directly, and the second through a peak detector 15. The output of the comparator 17 is connected to the start input of the counter 19, the counting input of which is connected to the first input of the clock generator pulses 21 (figure 2). In addition, the output of the comparator 17 is connected to the synchronization input of the trigger 18 (FIG. 3). The trigger output is connected to the trigger input of the comparator 17, the input of the bit switch 16, the output of which is connected to the second input of the comparator 17, and to the input of the delay and reset circuit 20 connected to the trigger input of the trigger 18 and the input of the control circuit 22 (Fig. 2). ). The cell controller 23, the display 24, the photo reader 25 and the printing device 26 are connected to the microcomputer 27. Using the CAMAC bus 28, communication between the delay and reset circuits 20, the counters 19, the control circuit 22, the clock pulse generator 21, the crate the controller 23 and timer 29. The timer input 29 is connected to the second output of the clock pulse generator 21.

The speed sensor 10 operates as follows.

Pulsed thermal energy is introduced into the flow by heating 5 fluid in areas of contact with heating elements 6 by passing current pulses from generator 12 through them. Heat marks sent by all heaters 6 are almost simultaneously transferred by fluid through pipeline 9 and are recorded thermal receivers 1-5, located behind each of the heating elements 6 separately at the same fixed distance in the direction of flow. Serial connection of N thermal receivers within each of the n series formed by them provides N-fold amplification of the useful input signal. The time elapsed by the thermal label of the distance E is counted from the moment of sending a current pulse by the generator 12 to the moment when the multiplicated signal from the row of thermal receivers reaches the maximum level. For each i-ro channel, this time interval will have its own meaning. 1 (i 1,2,3, ..., p), corresponding to the pattern of flow velocity distribution over the cross section. The first to reach the maximum level is a signal from a series of thermal receivers along which the fluid moves at the highest speed; the last will be the signal of the row of the pipe closest to the wall 9. The average flow velocity along the i-ro row of thermal receivers V; e / i :; . To calculate the flow rate, the following algorithm is adopted. The flow section is divided into m zones (Fig. 4). If the speed sensor 10 contains n channels, then m (n + 1) / 2 coincides with the number of i-ro p and thermal receivers located along the axis of the pipeline 9. The outer boundary of the j-th zone (J 1,2,3 ,. .., t) is a circle of radius RJ (2j-1) R, where R is the radius of the central-oral zone through which the heat passes at an average speed V,. The second flow rate V is determined as follows: V irRvPtv .-, e (rH (n, 4, -i, {mi.j) The total flow per time t is defined as follows: v4, vX, 26 where P is the number of generator starts current pulses 12 in time ki where Tj, is the k-ro measurement time, i.e. the interval between (kl) -M and k-th pulses from the generator 12. + where Uj, is the time to reach the maximum signal level from a series of thermal receivers, along which the liquid moved with the lowest speed during the k-ro measurement, and the processing complex of the obtained results at the time of processing. After starting the program, located in the microcomputer, the control circuit 22 starts the current pulse generator 12 and sets the controllable timers 13 completely identical in their electrical circuits to the initial state, in which the trigger inputs of the comparators 17 are set and the signals from the outputs the comparators enable the counters 19 to count the pulses from the clock pulse generator 21. The pulses from the other generator output go to timer 29, which determines the end time of the measuring complex. The i-ro channel signal is fed to the input of the corresponding controlled timer 13, where the amplified operational amplifier 14 is fed to one comparator input. 17 directly, and to its other input through the peak detector 15. When the signal reaches the maximum, maximum level, a comparator 17 is triggered, which with its output pulse stops counter 19 and flips the trigger 18. The pulse from the trigger output determines the following sequence of signals: trigger reset the input of the comparator 17, which eliminates the possibility of its switching to the initial state, opening the bit 16 and the bit of the peak detector 15; starting the delay and reset circuit 20. The output signal of the delay and reset circuit returns 7 to the previous condition trigger 18, the signal from the output of which locks bit 1 sets the trigger input of comparator 17 and also sends a counter 19 stop signal to control circuit 22. Counter The i-ro channel stores the number A; cl- / t, where is the pulse repetition period of the generator 21, Ots and determines the time L; for which the liquid transferred the heat label from the heaters to the thermal receivers of the i-ro channel. After all the counters 19 are stopped, the control circuit 22 sends to the crate controller 23 a request signal, on reception of which data from the counters via the CAMAC 28 highway and the crate controller come to the microcomputer 27. Using this data, the microcomputer 27 calculates the second consumption of V and puts it in memory. Then, the control circuit 22 again starts the current pulse generator 12, sets 26 controlled timers 13 to the initial state, and the cycle of determining the second consumption rate is repeated. After the time t, for which the fluid flow V is required to be determined, timer 29 is triggered, the output of which allows the microcomputer 27 to proceed to determining the final result and outputting it to the printing device 26. The operation of the measuring complex is monitored through the display 24. The program is entered into a micro-computer through a photo reader 25. The use of the invention as a result of the multiplication effect of the useful signal by each series of thermal receivers in combination with the distribution of these rows over the cross section of the pipeline using the computer system on the basis of a microcomputer and hardware CAMAC allows to take into account the actual velocity profile and determine the liquid flow rate with high accuracy.

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Claims (1)

HEAT FLOW METER, comprising a current pulse generator, heating elements and thermal detectors, a measuring complex, characterized in that, in order to improve the measurement accuracy, the heating elements and thermal detectors are installed in the flow on surfaces that coincide with the axial section of the pipeline of the fixed plate at equal distances from each other along its length, while each of the heat detectors follows its own heater, being at the same fixed distance from it, the heating elements are located s on both sides of the board, made in the form of orthogonal narrow bends to the pipeline axis and connected in parallel to common buses connected to the current pulse generator, the heat detectors form several rows (channels) parallel to the pipe axis along the board width with a constant step between by them and with a shift of the rows of one side of the board in relation to the rows of the other side by half a step, each channel contains the same number of series-connected thermal receivers, the measuring complex contains those made in the CA standard MAK timer, clock generator, control circuit, clock controller, controllable timers, as well as microcomputers, a photo reader, a display and a printing device, the output of each of the thermal detector channels being connected to the input of the corresponding controlled timer, the first output of the clock generator connected to the second inputs controlled timers, the second output of the generator is connected to a timer, controlled timers, a clock, timer, control circuit and crate controller are connected to the KAMAK trunk, you the control circuit is connected to the input of the current pulse generator, to the output of which heating elements are connected, the microcomputer is connected to a photo reader, a printing mechanism, a display and a crate controller, while the input of each of the controlled timers is the input of the operational amplifier, the output of which is connected to the first directly with the input of the comparator, and with the second through the peak detector, you> the comparator stroke is connected to the counter start input, connected by its counter input to the first output of the clock pulse generator, the second output of which is connected to the timer input, the comparator output is also connected to the trigger synchronizing input, the output of which is connected to the comparator trigger input, the discharge key input, the output which is connected to the second input of the comparator, and to the input of the delay and reset circuit, the output of which is connected to the input of the control circuit and to the installation input of the trigger.