Helpful information. How the heating meter works: the principle of operation and types of heat meters

Ph.D. I.P. Andreev, Doctoral student of the Samara State Technical University, director of CJSC "Tochenergo", Togliatti

The article discusses typical ways distortion of meter readings and methods of dealing with them.

One of the main federal problems of accounting and saving natural and energy resources (PER) during their extraction, transportation, processing, storage, sale and use is the distortion of accounting for PER and their losses, especially in monetary terms. The problem of accounting for PER losses has a number of negative organizational and methodological features hidden from the general public, which are not characteristic of civilized accounting systems.

There is a widespread unpunished practice of material incentives for employees to receive income ("savings") by fraudulently unauthorized distortion of meter readings.

Consider the typical ways of distorting meter readings and methods of dealing with it.

1 . Use of hydrodynamic factors to change instrument readings

One of the most affordable ways to change instrument readings using improvised plumbing tools is to change the velocity diagram and flow swirl using a non-standard sealing gasket installed between the straight section at the flow inlet to the sensor and the sensor itself.

The designs and materials of gaskets can be very different. It is possible to reduce the inner diameter of the gasket and even make screw threads with swirling flow. If the gasket is soft, starts to vibrate and cause flow pulsations, then theoretically this can reduce the effect, because. flow pulsations lead, for example, to overestimation of turbine meters. If the gasket is internally threaded and is a flow swirl but not properly designed, this will cause additional pressure drop and possible noise in the piping. A flow swirler can also be installed in front of a straight section along the flow, especially if, according to the recommendation of the manufacturer of the device, a small length of the section is allowed (3 ... 5 nominal diameters).

Dirty filters, dirty internal surfaces pipelines and partially open gate valves (cranes) installed near the flow sensor also cause changes in the velocity diagram and lead to errors. There is a known case when, due to partial clogging of the inlet filter, the readings of the heat meter in one of the Moscow hotels were underestimated by 30%.

Another case was registered by the author at one of the fruit and vegetable bases, where a partial overlap of the inlet valve in front of the heat meter in warm weather systematically led to an underestimation of the flow rate by about an order of magnitude. Increasing the flow rate to the lower limit of the operating range, on the contrary, led to the restoration of reliable readings. However, it has not been determined exactly whether the underestimation of readings is related to the velocity diagram or the sensitivity threshold of the flow measurement channel.

Air flow with centrifugal pump installed in the line, or an external compressor also causes a change in meter readings. It is well known to use compressors for the purpose of overcharging meters at petrol stations. At the same time, the volume counter, due to the physical features of its work, displays the volume of not only the product, but also the air pumped with the product.

At the same time, airing the flow using pumps in Food Industry, in particular in the alcohol industry, leads to an unfavorable imbalance for the manufacturer of volumes measured by the counter and determined by the number of bottles filled through the dispenser. The explanation for this phenomenon is quite simple - air is dissolved in water in an amount of up to 3% by volume (at atmospheric pressure), and with a strong shake, like from champagne, it is released. To get rid of this phenomenon, it is necessary either to change the pump, or to reduce the flow rate, or to install the meter downstream of the pump. If an air collector is installed, then it is necessary to instrumentally check the effectiveness of its operation. It often happens that air collectors, even complex in design, do not create an extinguishing effect on food products.

Changing the roughness of surfaces. It is known that the inner walls of the pipe and the blades of the turbine must have rough surfaces. If the surface of the blades is very smooth, such as coated with a film or polished, this will make it very difficult for the flow to turbulize along the blade and reach the critical Reynolds number. In turn, this will significantly increase the slip of the turbine in operation and lead to a noticeable underestimation of the meter readings (Fig. 1). For information, on gliders, a thread is specially pulled in front of the wings in order to cause flow turbulence and a large, at the same angle of attack, lift.

Another way is to replace the calibrated washers and impellers of verified meters with fake ones, with a different washer hole diameter or a different impeller screw thread angle. In the pipe, the sensitive elements are not visible, and when opened, it is almost impossible to detect a defect or accuse the customer of a fake of deliberately understating the readings.

2. Mechanical and magnetic braking

Mechanical braking of the impeller with a fishing line passed through a tap or with a filter plug, when organizing apartment accounting water consumption. The plug idea is especially effective, as it clearly demonstrates the incompetence of designers and inspectors in matters of instrumentation.

If mesh filters in apartments are installed downstream of water meters and are not sealed, then switching flows through filter plugs using flexible hoses leads to “twisting” of meter readings.

Magnetic braking of impellers and magnetic couplings by means of an external permanent or rotating magnetic field possible, but if there are ferromagnetic screens on the meter, it is usually inefficient. Apparently, more research is needed on this issue.

As for vortex counters with a constant magnetic excitation field, then, as shown by our experimental studies, there are opportunities to change (falsify) the meter registered lower limit measurements on the threshold of sensitivity. In other words, if the vortex counter's electronic recorder is set to 1 m 3 /h, then with artificial magnetic field compensation, operation can occur at a much higher flow rate, for example, at 4 m 3 /h. Volumes with flow rates up to the given value will be recorded at the lower presetting. All that is required for this is to occasionally connect to the magnetic system of the vortex sensor an external electromagnetic system from a power supply unit and a solenoid, the core of which is a vortex sensor magnet. 2-tube measurements require 2 solenoids. However, for technological measurements, the vortex sensor of the described design may be of interest.

3. Temperature factors

At the same metering unit, our instrumental surveys revealed the fact of underestimation of the heat carrier supply temperature readings by 20 °C, which gave a large consumer almost 50% underestimation of the heat metering unit readings. The source of the defect was a non-standard thermowell (thermowell) made of a segment water pipe, which protruded about 8 cm above the supply pipeline and was filled to the top with liquid. Since thermowells are not subject to inspection when they are installed in a pipeline, their special design and filling with liquid above the operating level of the RTD sensing element can also contribute to the change in meter readings.

You can replace the resistance thermometer with a fake one or connect a resistor of a certain rating in parallel with it or the communication line. The effect is similar to the previous one, and in the presence of a hidden switched resistor, it is difficult to detect the cause of underestimation during inspections.

4. Influence of cable asymmetry and correct grounding

At 2 metering stations of the same type, a discrepancy of approximately 4% was found in the readings of digital flow meters and computers connected to them, and, oddly enough, in one case the readings of the flow meter were higher than those of the calculator, and in the other, vice versa. This fact can be explained by the fact that instead of a cable with cores of the same section, asymmetric wires enclosed in a metal hose were used, as well as by incorrectly executed grounding, which led to loop currents of the corresponding direction.

5. Incorrect sealing and the presence of a keyboard

The presence of soft, especially plasticine, seals on the components of the metering units allows you to make impressions from the seals and open the metering units with the provision of a change in readings by any accessible way. Remarkably, but once tax office refused the author to withdraw samples of lead seals from the investigated metering station alcoholic products, because seals with cut ends of the wire were subject to accounting. Perhaps, in the delivery of used seals, the meaning is laid not only of the disposal of lead, but also deep meaning counterfeit control (according to outward signs and composition).

After completing the training of one of the thermal inspections, the author asked to perform a control sealing of any metering unit so that it was impossible, as promised, to underestimate the readings in 5 minutes. What was the general amazement when the author, having examined all the seals, instead of the planned method, opted for the seal of the supply pipeline thermometer and managed to unscrew the resistance thermometer without breaking the seal. The entire operation to underestimate the readings of the metering station took 2 minutes.

The presence of a keyboard allows you to "zombify" the calculator program and control the change in readings directly from the keyboard using only commands known to scammers. In the first developments of domestic heat meters, the power supply of the flowmeter and calculator was separate. Disconnecting the flow meter from the network did not lead to the shutdown of the operating time counter in the calculator. Until now, some meters, installed by the author back in 1994, operate in the mode of unauthorized underestimation of readings, and heating networks compensate for their losses by increasing energy tariffs. Any software tricks of developers in the form of alarms, as it turned out, are easily removed and do not give any benefit, except for problems in operation.

6. Unbalanced Accounting

When organizing a metering system that includes a certain number of metering units combined into a single system, there is an imbalance in the entire system with a significant excess of the resulting error that the entire system as a whole should have. For example, at night apartment meter shows the amount of water consumed by the consumer, and the meter at the entrance to an apartment building, for example, a vortex type, does not respond to the flow due to the presence of a threshold flow rate. Such an imbalance seems to be “beneficial” to the residents of the house, if you do not take into account that unbalanced accounting according to the standards for measuring Information Systems and norms of accuracy is illegal.

Findings:

Thus, from the foregoing, priority measures arise to reduce the uncertainty and distortion of the commercial accounting of PER and their losses:

To improve the reliability of accounting measurements of energy and natural resources metering units must undergo state verification by the bodies of the State Standard of the Russian Federation directly at the places of operation without violating the integrity of metering units.

On strategically important routes for the transportation of natural and energy resources, in addition to metrological control, tax (balance) control should be carried out using portable calibrators, communications, computers, statistical processing methods and other tools for detecting excess losses.

The control of metering stations, interpreted in a peculiar way and actually carried out by power engineers, is illegal, brings huge annual losses to consumers of resources and the treasury in the form of a shortage of products, taxes, customs duties and the presence of losses (up to $ 100 billion annually), hinders technical progress. It is advisable to exclude illegal actions from the Accounting Rules and everyday practice and bring them into line with the standards and basics of metrology of measuring information systems.

It is necessary to import the well-known, primarily tax and customs, requirements for the protection of goods and commercial information from unauthorized access to accounting nodes. Specific methods and means of protection must pass certification tests.

Literature

1.Andreev I.P. Common Mistakes organization of commercial heat metering. Energy Efficiency, CENEf, 1995, No. 9.

2. Andreev I. P. Instrumental survey and detection of defects in urban systems of heat and water accounting. Energy Efficiency, TSENEF, 1998, No. 21, p. 20-22.

3.Andreev I.P. About metrological support of

accounting for energy resources. Report to the Scientific and Technical Committee of the State Standard of the Russian Federation, protocol No. 10 dated June 27, 2000.

4. Andreev I. P. Portable calibrators for rejection, adjustment, operational and metrological control, certification of commodity pipeline metering systems for energy and natural resources and provision of services to eliminate metering defects. The project that won the Russian Competition of Innovative Projects "Science-Technology-Production"

A heat meter is a device for recording the consumed heat carrier, which is currently very profitable, as it allows you to save money by paying only for the consumed heat, eliminating overpayment.

The important point is right choice type of device depending on the place of installation and design features heating networks, as well as the conclusion of an agreement with a service organization that will control technical condition devices.

There are many models of heat meters that differ in design and size, but the principle of how the heating meter works remains the same as on the simplest device that measures the temperature and water flow at the inlet and outlet of the heat supply pipeline. Differences appear only in engineering approaches to solving this issue.

The operation of the heat meter is based on the principle of calculating the amount of heat using data taken from a coolant flow sensor and a pair of temperature sensors. There is a measurement of the amount of water that has passed through the heating system, as well as the temperature difference at the inlet and outlet.

The amount of heat is calculated by the product of the flow rate of water passing through heating system, and the temperature difference between the incoming and outgoing coolant, which is expressed by the formula

Q \u003d G * (t 1 -t 2), gcal/h, in which:

• G – mass flow water, t/h;
• T1,2- temperature indicators of water at the inlet and outlet of the system, o C.

All data from the sensors are sent to the calculator, which, after processing them, determines the value of heat consumption and records the result in the archive. The value of the consumed heat is displayed on the display of the device and can be taken from any moment.

What affects the accuracy of the heat meter

Techem compact V

A heat meter, like any precision device, has a certain total error when measuring consumed heat, which is the sum of the errors of temperature sensors, a flow meter and a calculator. In apartment accounting, devices are used that have an allowable error of 6-10%. The actual error rate may exceed the base one, depending on the technical characteristics of the components.

The increase in the indicator is determined by the following factors:

1. The amplitude of the incoming and outgoing coolant temperature, which less than 30 o C.
2. Violations during installation in relation to the requirements of the manufacturer (when installed by an unlicensed organization, the manufacturer withdraws warranty obligations from it).
3. Inadequate quality of pipes, hard water used in the coolant, and the presence of mechanical impurities in it.
4. At a coolant flow rate below minimum value, indicated in technical specifications devices.

How is heat consumed measured?

It is customary to calculate the tariff for consumed heat in gigacalories. The unit of measurement refers to non-systemic, and has been traditionally used since the existence of the USSR. Appliances made in Europe calculate the consumed heat in GigaJoules (SI), or a generally accepted international non-systemic unit kWh (kWh).

Types of heat meters

All heating meters available for purchase are divided into the following types:

• Tachometric or mechanical

It measures the amount of coolant that has passed through the section of the pipe using a rotating part. The active part of the device can be screw, turbine or in the form of an impeller.
The devices are affordable and easy to use. Weak side similar devices - sensitivity to dirt and settling inside the mechanism of dirt, rust, and to water hammer. For this, a special magnetic mesh filter is provided in the design. Also, the devices are not able to store the data collected per day.

• Ultrasonic

More commonly used as a general counter apartment building. It has varieties:

1. frequency,
2. temporal,
3. doppler,
4. correlation.
   It works on the principle of generating ultrasound passing through water.

The signal is generated by the transmitter and picked up by the receiver after passing through the water column. Guarantees high measurement accuracy only with sufficient purity of the coolant.

• Electromagnetic

Differs in high accuracy of indications and cost. The operation of the device is based on the principle of passing a magnetic field through the coolant flow, which reacts to its state. The device needs periodic maintenance and cleaning. It consists of a primary converter, an electronic unit and temperature sensors.

• Vortex

It works on the principle of measuring the number and speed of vortices. It is not sensitive to clogging, but reacts to the appearance of air in the system. The device is installed in horizontal position between two pipes.

How to present evidence correctly

An apartment heat meter is functionally much simpler than a modern one. mobile phone, but users periodically have misunderstandings about the process of taking and sending display readings.

To prevent such situations, before starting the procedure for taking and transferring readings, it is recommended to carefully study his passport, which provides answers to most questions related to the characteristics and maintenance of the device.

Depending on the design features of the device, data collection is carried out in the following ways:

1. From the liquid crystal display by visual fixation of readings from various sections of the menu, which are switched by the button.
2. ORTO transmitter, which is included in the basic package of European devices. The method allows you to display on a PC and print extended information about the operation of the device.
3. M-bus module is included in the delivery of individual meters in order to connect the device to the network of centralized data collection by heat supply organizations. So, a group of devices is combined into a low-current network with a twisted pair cable and connected to a hub that periodically polls them. After that, a report is generated and delivered to heat supply organization or displayed on the computer display.
4. Radio module, supplied with some meters, transmits data wirelessly over a distance of several hundred meters. When the receiver enters the range of the signal, the readings are recorded and delivered to the heat supply organization. So, the receiver is sometimes attached to a garbage truck, which, when following the route, collects data from nearby counters.

Archiving readings

All electronic heat meters store in the archive data on the accumulated indicators of thermal energy consumption, operating and idle time, coolant temperature in the forward and return pipelines, total time developments and error codes.

By default, the instrument is set to various modes archiving:

• hourly;
• daily;
• monthly;
• annual.

Some of the data, such as total operating time and error codes, can only be read using a PC and special software installed on it.

Transfer of readings via the Internet

One of the most convenient ways transmission of indications of consumed thermal energy to institutions for its accounting is transmission via the Internet. Its convenience and practicality lies in the ability to independently control payments and debts, as well as track heat consumption in different periods without staying in queues and spending a small amount of time.

To do this, you must have a personal computer connected to the network and the address of the website of the controlling organization, as well as a login and password. personal account, after entering which a form for entering readings will open. To prevent the occurrence of disagreements in the event of a possible failure or malfunction on the site, it is advisable to take “screenshots” of the screen after entering information.

Breakdowns and repairs

Maintenance of the device is limited to maintaining it in working condition, regular inspection, and avoiding causes that cause premature wear and tear. According to paragraph 80 of the Rules for the commercial accounting of the coolant, all maintenance and control of the correct operation of the meter is carried out by the consumer. On the part of the owner, he special care does not need.

lithium battery or the batteries that power the device are not suitable for reuse and should be disposed of if they fail.

If any malfunction in the operation of the metering device is detected, the consumer must notify the service company and the organization providing heat supply within 24 hours. Together with the arrived authorized employee, an act is drawn up, which is then transferred to the heat supply organization with a report on heat consumption for the corresponding period. In case of untimely notification of a breakdown, heat consumption is calculated in a standard way.

The service company will provide services to repair or replace the meter, and may install a replacement device during the repair. The cost of installation and dismantling, repair and other services is regulated by an agreement between the consumer and the service company.

Error logging

As standard, heat meters are equipped with a self-testing system that can detect inaccuracies in operation. The calculator periodically queries the sensors, and if they fail, fixes an error, assigns a code to it and writes it to the archive. The most common reported errors are:

1. Incorrect installation or damage to the temperature sensor or flow device.
2. Insufficient battery charge.
3. The presence of air in the flow path.
4. No flow if there is a temperature difference for more than 1 hour.

Removal and installation of the heating meter

Before installing a heating meter in an apartment or apartment house, specialists of specialized companies with permits for this type of work are invited. Based on the specific situation, they can take on the following obligations:

1. Develop a project.
2. Submit documents to certain authorities in order to obtain permits.
3. Install and register the device. In the absence of registration, payment for the supplied heat is made according to the established tariffs.
4. Carry out test tests and put the device into operation.

The developed project should include the following points:

1. Type and device of the model, which is designed to work in a particular heating system.
2. Necessary calculations for heat load and coolant flow.
3. Scheme of the heating system with the installation location of the heat meter.
4. Calculation possible losses heat.
5. Calculation of payment for the supply of thermal energy.

Checking heating meters

As a rule, a quality device arrives at the point of sale initially tested. The procedure is carried out at the factory, which is evidenced by a stamp with a record corresponding to the record in the documentation. In addition, the documents indicate the calibration interval.

After the expiration of this period, the owner of the device must contact service center manufacturer or an organization authorized to check and install the meter. There are companies that, after installing the device, are engaged in its maintenance.

Periodic confirmation of the metrological class, or in a word, verification, is carried out by a specialized company that has pouring installations, as well as a permit issued by the metrological supervision authorities.

The calibration period depends on the type of device, and averages 4-5 years.

For this purpose, a metrologist is called, seals are removed, a specialist from a service organization dismantles the meter and sends it for verification. After checking and reassembly, the device is sealed.

A heating meter is a device for accounting for thermal energy, which allows you to save money by paying only for the actually consumed service. Failure to comply with the conditions below will lead to the inability to pay for heat according to the meter readings.

For the correct and long-term operation of the device, it is important to choose the type of meter, which must be present in the state register of measuring instruments acceptable for use, and also have metrological certification in the appropriate authority.

The device is installed by an enterprise licensed to carry out such work.

With filled pipeline and closed shutoff valves(displayed flow must be 0) g1 values ​​are displayed.

Likely cause:

1. An electric current flows through the pipeline, on which a heat meter with a primary flow converter is installed.

2. Malfunction of valves

1. Since heating network not designed to transmit electricity, find and eliminate the source of electric current.

2. Let the current pass through the area where the heat meter is installed, as follows:

Insulate flange bolts. For devices with threaded connection- embed flanges on nearby sections of pipelines or use the flanges of adjacent fittings;

Rice. 1. Diagram of insulating flange bolts

Perform electrical shunting of the pipeline section on which the heat meter is installed with a shunt bus. Use steel wire with a diameter of 6...8 mm. Connection method - welding.

Rice. 2. Scheme of electrical shunting of the pipeline section.

With the assumed uninterrupted flow of the coolant, instability of the readings g1 (g2) is observed.

Most likely causes:

A foreign body got into the channel or the primary flow converter connected to it.

Elimination Methods:

Dismantle PPR (primary flow converter). It is possible to install a filter if the problem persists.

With the expected ratio of flows in the supply and return pipelines, there is a difference in readings between g1 and g2. In this case (g1-g2)/g1*100 > 2%

Most likely causes:

1. A foreign body has entered the channel or the primary flow converter connected to it.

2. The requirements for straight sections of pipelines have not been met.

3. Malfunction of the primary flow converter.

Elimination Methods:

In the event that no clogging of the flow path is detected, send the flow transducer for repair and verification

No signal from flow transducer channel V1.

Most likely causes:

1. The direction of the flow in the pipeline does not correspond to the direction of the arrow printed on the body of the primary converter

2. An electrically conductive foreign body got into the channel or the flow converter connected to it and shorted the electrodes to the body.

Diagnostics:

1. Analyze the correspondence of the direction of the arrow to the direction of flow.

2. Dismantle the PPR, inspect the flow path

3. Ring the power supply circuit from the calculator.

Elimination :

1. Remount the PPR.

2. Clean the flow part and install a magnetic-mechanical filter before the flow converter.

3. Restore the network when it breaks.

Breakage or short circuit of temperature sensors of channel T1 or T2.

Most likely causes:

1. Temperature sensors are not connected or another device is connected instead (flow sensor).

2. Break or short circuit in the wires connecting the temperature sensors to the calculator or the temperature sensors are faulty.

Diagnostics :

1.Check if the connection is correct.

2. Disconnect the wires from the temperature sensors, measure their resistance (resistance from 500 to 780 Ohm is considered normal). If the resistance goes beyond the mentioned limits, this may indicate a break, short circuit or a malfunction of the temperature sensors.

Elimination :

1. Carry out a new installation with the selected measuring circuit.

2. Replace temperature sensors if a malfunction is found in them

T1 2.