Device for automatic control of tank filling

 

(57) Abstract:

The inventive device includes a transformer with 1 primary and secondary windings, rectifiers 3, 19, a storage capacitor 4, a current limiting resistor 6, the guard electrode 5, the electrodes 7 and 8 of the upper and lower levels, resistors 9, 10, 14 - 17, 22, elements antijamming performed by the capacitors 1, 2 and 13, the measuring unit 11, autocompensation leakage current, in the form of capacitor 18 and transistors 20, 21, a voltage amplifier, made in the form of resistors 23, 24, actuating relay 25. 4-6-23-21-2-19-18-4-3-2, 23-24-17-12-11-25, 24-16-13-11, 19-22-21, 19-20-16-13, 20-17-12, 7-9-12, 8-10-13, 5-14-12, 5-15-13, 4-14, 4-15. 1 the sludge.

The invention relates to devices for automatic control of tank filling bulk and liquid conductive materials, such as coal, rock, silo, flour, slurries, chemicals, etc., and is intended primarily for use in explosive atmospheres for mining, chemical, oil industry and in agriculture.

A device for monitoring the level of granular and liquid explosive atmospheres and is based on the principle of measuring the resistance between the electrode Datterode, the measuring unit associated with said sensor line, the Executive body and the power source (ed. St. USSR N 489958, CL G 01 F 23/24).

The condition of such a device is the presence in the chain of positive feedback of less resistance than in the circuit of the negative feedback. Upon contact of the electrode with controlled material resistance in the circuit of the negative feedback becomes much smaller than in the chain of positive feedback comparator, which leads to the disruption of the relaxation oscillations, and hence the operation of the device.

The sensitivity of the device is determined by the sensitivity of the comparator and depends on the transition resistance of the medium between the electrodes and the magnitude of the applied voltage. In terms of leakage along the surface of the sensor caused by the presence of conductive dust and moisture, the resistance between the measuring and guard electrodes can be reduced to several tens of kilo-ohms. In this regard, the resistance values in the circuit of the positive and negative feedback comparator aligned, which leads to false positives device for level control. Consequently exploiting leakage current on the surface of the sensor affects the control of the two fill levels of the tank. This is because the conductive layer of dust between the guard electrode and the grounded casing of the tank, serving one of the measuring electrodes, reduces ceteris paribus the sensitivity is doubled compared to a single-level device.

Closest to the present invention is a device for two-level control tank fill conductive medium containing transformer with secondary windings, one of which is through a rectifier connected to the capacitor, which is the online source, one plate of which is connected to the guard electrode, and the other through a current limiting resistor to ground, and a two-channel measuring unit, the inputs of which through the elements and anti-jamming attached to the upper electrodes, the lower level and the guard electrode, and the outputs of the measuring unit through the opto-block attached to the Executive body.

The device provides an effective two-level control tank fill in hazardous environment. This is done by the decision of the measuring unit, in the input circuits is set to the element anti-jamming, and the output circuit through the opto-block tool is non-output circuits, the power transformer is made resistant to short circuits, secured the required intrinsic safety of creepage and clearances.

The device operates as follows.

When the electrode touch the bottom level of the filling material in the probe circuit from the operational source begins to flow a constant current through the channel of the lower level of the measuring unit is amplified and fed through opto unit and a ballast resistor to the output relay. The value of the ballast resistor is selected such that the current through the actuating relay not sufficient for its operation, but exceeds the holding current of the relay in drawn condition when it is triggered. Therefore, when the electrode touch the bottom level of the Executive relay is not triggered. When reaching the fill tank of the electrode material of the upper level of the amplified signal on the channel of the upper level via opto-block is fed directly to the output relay, which is triggered and held in the attracted state of the chain, prepared by the control elements of the lower level as long as the tank is emptied, i.e. until the moment when there is no contact electromyostimulation operational amplifier of the measuring unit, which is quite high. However, since the power source to ensure the intrinsic safety is made with a fairly high internal resistance, the occurrence of leakage current on the surface of the upper and lower level leads to a significant decrease in the sensitivity of the device. As a consequence, in some cases, even for large values of the gain of the operational amplifier, is unable to obtain the required sensitivity of exposure to dust and moisture level sensors, and therefore, to ensure the high reliability of the level control device.

The purpose of the invention improving the reliability.

The aim is achieved in that in a device for automatic control of zapolneniya tanks conductive medium containing a transformer, one winding of which is through a rectifier connected to the capacitor, which is the online source, one plate of which is connected to the guard electrode of the sensor, and the other through a current limiting resistor to ground, and the measuring unit, whose input is through the elements of anti-jamming is connected to the measuring and guard electrodes of the sensor, and the output connected to the ISA lining of which is connected to the guard electrode, and the other through a rectifier connected to the winding and is connected to the collector of the first transistor, the base of which is connected through a resistor with its collector and the collector of the second transistor, the emitter of which is connected to the guard electrode, and the base through a resistor voltage divider connected to ground, and via a second resistor of the voltage divider to the emitter of the first transistor through a resistor (resistors) connected to the input (inputs) of the measuring unit.

The invention is illustrated in the drawing.

Device for automatic control of tank filling conductive medium includes a transformer 1 with the secondary winding 2, which through the rectifier 3 is connected to the storage capacitor 4, which is the operational source. One plate of storage capacitor 4 connected to the guard electrode 5 of the sensor, and the other through a current limiting resistor 6 to the ground. The measuring electrodes 7 and 8 respectively of the upper and lower levels are connected through resistors 9, 10 to the inputs of the measuring unit 11, through which the elements antijamming performed by the capacitors 12, 13 and resistors 14, 15 are attached to the guard electrode 5, and through the resistors 16,jenster 18, one plate of which is connected to the guard electrode 5, and the other through the rectifier 19 is connected to the winding 2 of the transformer 1. The collector of transistor 20 is connected to the capacitor 18 and the rectifier 19 and through a resistor 22 is connected with its base connected to the collector of the transistor 21, the emitter of which is connected to the guard electrode 5. The base of the transistor 21 through the resistor 23 of the voltage divider connected to ground, and through resistor 24 to the emitter of transistor 20 is connected to the resistors 16 and 17, which are attached to the inputs of the measuring unit 11. The output of the measuring unit 11 connected to the actuating relay 25.

The device operates as follows.

When empty the tank 26, the filling level of which is controlled by the current from the operational source 4 to the measuring circuits through the input of the measuring unit 11 does not leak. Executive relay 25 is deenergized.

As the load of the tank 26, the body of which is grounded lower electrode 8 deals with fillable reservoir of electrically conductive material. As a result, through the entrance of the lower level of the measuring unit 11 current flows through the circuit: "plus" of the capacitor 4, the entrance of the lower level of the measuring unit 11, the PE the ballast resistor 6, minus the condenser 4. The magnitude of this current is more than the reference current, locking the measuring unit 11, which is determined by the voltage on the capacitor 18 and resistor 16 (the resistance of the emitter-collector junction of transistor 20, which is in a state of conduction can be neglected). Consequently, at the output of the channel of the lower level of the measuring unit a signal preparing circuit actuation of the actuating relay 25.

Touch to fill the tank 26 of electrically conductive material of the electrode 7 of the upper level of operating current through the entrance of the upper level of the measuring unit 11 exceeds a specified threshold, which is determined by the voltage at the capacitor 18 and resistor 17. At the output of the channel of the upper level of the measuring unit 11 a signal, which circuit prepared by the channel of the lower level, results in actuation of the actuating relay 25.

During unloading of the tank 26 to the electrode 7 of the upper level loses electrical contact with the controllable material. The output of the upper level of the measuring unit 11, the signal is missing, but the Executive relay 25 remains in the triggered astray electrical contact with the material, the fill level can be monitored. Output channel of the lower level of the measuring unit 11, the signal becomes close to zero. Executive relay 25 is de-energized, indicating that the level of controllable material has reached the lower limit.

The specified mode is saved when the surface level sensors are not "contaminated". With the appearance on the surface of the sensors 27 and 28, conductive dust and moisture begins to operate autocompensation active leakage currents.

The principle of operation of autocorrelator based on the resistance change of the transition, the emitter-collector of transistor 20, which is controlled by the transistor 21, the offset on the basis of which is set by the voltage divider 23, 24, varies depending on the voltage between the guard electrode 5 and ground.

The tension between the guard electrode 5 and ground depends on the ratio between the ballast resistor 6, the value of which is chosen from the condition of intrinsic safety, and the equivalent resistance of the conductive dust and moisture on the surface of the sensors 27, 28. The more surface sensors are coated with a layer of dust, the less operational current in the measuring circuit unit 11.

Due to the fact that the capacitor 4, which is the operational source and the capacitor 18, which is the reference source respectively through rectifiers 3 and 19 are connected to the same winding 2 of the transformer 1, the change of voltage fluctuations in the network do not change the differential current through the input of the measuring unit 11.

In this work awakeningaimee tank.

Thus, the introduction of autocompensation leakage current on the surface of the sensors allows to increase the operational reliability of the device control of tank filling. This reduces operational costs associated with the need for a preventive cleaning of the sensors from conductive dust, a thick layer which in some cases led to the loss of the monitoring device.

DEVICE FOR AUTOMATICALLY CONTROLLING the filling of the TANKS containing the transformer, the first and the second terminal of the secondary winding of which is connected respectively with the first and through the first rectifying diode with the second plates of a storage capacitor, the third resistor, the output relay, the first and the second inputs of which are connected respectively to the first and second outputs of the measuring unit, the second and the third input of which is connected to the first plates respectively of the first and second elements and anti-jamming, the second plates are connected respectively with the first and fourth inputs of the measuring unit and through the first and second resistors connected to the electrodes respectively of the upper and lower levels, while the first and second plates nucopia bus, characterized in that it introduced the fourth and fifth resistors connected to the first plates respectively of the first and second elements and anti-jamming, sixth and seventh resistors connected to the second plates, respectively, the first and second elements and anti-jamming, a voltage divider, a second rectifier diode and autocompensation leakage current, made in the form of first and second transistors and a capacitor, the first plate through which the second rectifier diode connected to the second terminal of the secondary winding of the transformer and is connected to the collector of the first transistor, which is connected through a third resistor with its base connected to the collector of the second transistor, the base through the first resistor of the voltage divider is connected to the shared bus and via a second resistor of the voltage divider is connected to the emitter of the first transistor and the second pins of the sixth and seventh resistors, while the guard electrode is made in two parts, to a connection point which is connected to the second findings of the fourth and fifth resistors, the emitter of the second transistor and the second capacitor plate of autocompensation leakage current.

 

Same patents:

The invention relates to devices for automatic control of tank filling bulk and liquid conductive materials, such as coal, rock, silo, flour, slurries, chemicals, etc

Ohmic transmitter // 2047843

The invention relates to measuring technique and can be used to indicate the presence or absence of fluid and discrete measurement of liquid level, including in the conditions of high temperatures, pressures and corrosive environment

The invention relates to techniques for measuring non-electrical quantities and can be used to determine the position of the boundary of two immiscible liquids with different dielectric constant of the level and volume of liquids in containers of arbitrary shape

The invention relates to the field of determining fluid levels, namely the alarms section of the phase viscous oil and condensate tanks, mostly in the condensate gathering tanks for thermal plants running on heavy fuel oil

The invention relates to the instrument and can be used for measuring liquid level

FIELD: measuring engineering.

SUBSTANCE: device comprises fuel level indicator and rheostat pickup made of an analogue-digital converter with the balance input. The three-position switch is connected with the lever indicator. The device additionally has three resistive dividers, voltage stabilizer, and shunting resistor made of a 0.003-0.006-Om resistor. The rheostat level pickup is mounted inside the fuel tank vertically, and its linear horizontal size at this level is directly proportional to the area of the tank section in the horizontal plane at this level.

EFFECT: expanded functional capabilities.

1 dwg

FIELD: measuring engineering.

SUBSTANCE: method comprises pressing unit reinforced by electrodes with simultaneous forming of insulator between the electrodes. The space that is defined by surfaces of the electrodes is filled with casting plastic mass. The pressure tightness is provided by tightening the insulator with electrodes by means of a nut.

EFFECT: enhanced reliability.

1 dwg

FIELD: the invention refers to measuring technique and may be used for controlling bulk and liquid materials.

SUBSTANCE: the oscillating indicator of a level has a sensible element( a probe) 1 connected with an anchor 2, a driving arrangement 4 in the shape of a coil with a ferromagnetic core and also a sensor 5 of the displacements of the anchor, a drive-pulse generator 6 and an amplifier 7 and a relay block 9 successively connected. The amplifier is spanned with a regulated negative feedback fulfilled in the shape of a resistor 8. The sensor 5 of the displacements of the anchor may be fulfilled in the shape of a coil with a ferromagnetic core. At that the section of the anchor 2 between the coils is fulfilled out of non-magnetic material that prevents electromagnetic connection between the coils providing protection from high frequency oscillations in the system anchor-coil-amplifier.

EFFECT: allows to control the levels of the bulk and liquid materials being present in aggressive mediums, under pressure,( discharge)and at temperature till 200 degrees.

2 dwg

Level meter sensor // 2276333

FIELD: instrument engineering.

SUBSTANCE: level meter sensor comprises hollow rigid base with the port in its bottom end, diaphragm, strain gage converter with box, flexible spacer arranged over periphery of the box, and tube whose one end is mounted pressure-tightly in the port of the support and the other end is connected to the space of the box. The diaphragm is made of a rigid material and mounted on the flexible spacer for permitting cooperation with the strain gage converter.

EFFECT: enhanced reliability and simplified structure.

1 dwg

FIELD: the invention refers to the field of instrument making and designed for control of the level of dielectric and current conducting liquids in hydraulic systems (fuel, freezing, accumulative etc) for example the level of oil or cooling agent in transport vehicles.

SUBSTANCE: the liquid level meter has a two-electrode capacitance sensor with an external 10 and interior 11 electrodes electrically connected with an electronic scheme having a stabilized source of power supply, an amplifier, a generator and a trigger. According to the first variant the capacitance sensor is fulfilled in the shape of a coaxial condenser "C". The interior electrode 11 of the sensor is fulfilled tubular and is mounted inside a fluoroplastic probing rod 12. The interior electrode 11 is connected to the input of a phase comparator which is additionally introduced in the scheme and whose output is connected with input of the trigger and the output of the last is provided with a line of delay and has two outputs - direct and inverse connected with a transistor key fulfilled with possibility of fulfillment of an operation "switched on" or "switched off". At that the electronic scheme is fulfilled on a digital integrated microchip. According to the second variant the interior electrode 11 of the coaxial condenser "C" is fulfilled tubular and is additionally provided with a protective shield 22. The shield 22 is fulfilled in the shape of a spiral spring out of bronze and electrically connected with the external electrode - the body 10 of the coaxial condenser "C".

EFFECT: increases sensitiveness and accuracy of measuring of the level of liquid.

6 cl, 4 dwg

FIELD: invention refers to control-measuring technique and is assigned for control and signaling about border of interface between mediums petroleum product-water in installations for purification water from petroleum products or watered petroleum products from water.

SUBSTANCE: sensor has flange, three electrodes with sleeves on their low ends filled with fresh water, moreover two of them are covered with dielectric insulation. Electrodes with sleeves are located inside tube of protective screen and are fastened in flange with aid of stuffing boxes-insulators. Screen in upper part has diaphragm ring with openings along circumference coinciding with openings in screen forming swinging compensator and is fastened to flange with aid of screws. Electrodes of sensor together with sleeves and electronic part form oscillating contour going in resonance at presence in space between electrodes of electric conductive medium (water) with following triggering of executive elements and at presence of water between electrodes of petroleum product resonance of contour stops.

EFFECT: increases reliability of work of sensor.

2 cl, 1 dwg

FIELD: physics, measurement.

SUBSTANCE: invention is related to the field of facilities for automation of different liquids level detection in industrial and household reservoirs, and also for detection of liquids availability and flow in pipelines. Method is based on application of two thermistors that have identical thermal characteristics, and includes heating of one of the thermistors by electric current and its cool-down due to heat transfer to environment, periodic measurement of voltage drop at thermistors, calculation of informative parameter, its comparison with threshold value and making decision on availability or unavailability of liquid at controlled level. At that one of thermistors is periodically heated by short pulses from power supply source. After heating is completed, ratio of non-heated and heated thermistors' voltages are repeatedly measured, and as informative parameter scaled time derivative is calculated by means of specified ratio measurement results array processing. Device for method implementation contains two thermoresistors, which are installed in sensitive element, connected to power supply source and which have temperature resistance coefficients (TRC) of the same sign and identical coefficient of heat emission in gas. Besides, it also contains analog-digital transducer and comparator, reference inlet of which is connected to source of reference signal, and outlet is connected with actuating device. Moreover, device is equipped with pulse switch and serially connected regulator of heating time and synchroniser, and also calculator of scaled derivative. For alarm on liquid flow availability, device is additionally equipped with the second comparator that is connected parallel to the first one, and the second actuating device.

EFFECT: higher efficiency of liquid level detection by increase of device actuation fast-action, reduction of power inputs and expansion of its application field.

13 cl, 3 dwg

FIELD: measuring technology.

SUBSTANCE: invention refers to a measuring device for determination of an amount d(V(z)) of conducting liquid of the conductivity LF by a capacity with vertically (z-direction) varied filling points. There is provided conductivity metre which among others has at least two electrodes extended in a z-direction. The capacitance parametres and/or the metres are ensured so that it/they can be described by means of at least one parametric function, fpi (V(z)) depending on V(z). At least one said parametric functions shall have exponential dependence on V(z). There is also described measuring element, and also method for determination of total amount of flowing liquid d (V).

EFFECT: simplified design of the device and method of measuring conductivity of the conducting liquid.

42 cl, 14 dwg

FIELD: physics.

SUBSTANCE: method if based on measuring capacitance of a double-electrode capacitive liquid level sensor, which in turn in any sequence measures capacitance of the double-electrode capacitive liquid level sensor and capacitance of the same sensor is measured after connecting a capacitive sensor of dielectric properties to it, after which the level h from the upper end of the double-electrode capacitive liquid level sensor is calculated using the formula:

, where h is the level of the liquid in the reservior; CA is capacitance of the double-electrode capacitive liquid level sensor; CB is overall capacitance of the double-electrode capacitive liquid level sensor connected in parallel to the capacitive sensor of dielectric properties; A, B and D are structural parametres of the double-electrode capacitive liquid level sensor and capacitive sensor of dielectric properties. The device for measuring liquid level has a double-electrode capacitive liquid level sensor made in form of a coaxial capacitor, and two cylindrical electrodes. The lower end of the inner electrode of the double-electrode capacitive liquid level sensor is connected to one of the electrodes of the capacitive sensor of dielectric properties through the closing contact of a reed relay, and the lower end of the outer electrode of the double-electrode liquid level sensor is connected to the second electrode of the capacitive sensor of dielectric properties.

EFFECT: high accuracy of measuring the level of different liquids, as well as elimination of measurement errors caused by change in dielectric permittivity of the measured liquid.

2 cl, 1 dwg

FIELD: physics.

SUBSTANCE: sensor for monitoring the level of a liquid has a housing and a printed-circuit board on which there is a substrate having one or two identical film resistors (thermistors) and contact pads (conductors). The printed-circuit board is in form of a plate, one short side of which is rigidly attached to the base of the housing and on the edge of the opposite free side there is a hole whose diameter is 2…4 times larger than the width of the substrate lying over the hole and made from thin heat-insulating material. Each film resistor (thermistor) is in 'point' form with dimensions in the range (0.15…0.5) mm • (0.5…0.5) mm and thickness not more than 0.0005 mm. The boundary surface between each film resistor (thermistor) and contact pads of the substrate (conductors) is in form of broken lines consisting of straight sections.

EFFECT: high mechanical strength of the structure.

3 dwg

Up!