Automation of boiler installations: description, device and diagram. Boiler fittings and instrumentation Kip for boiler houses and heat supply facilities

The development of a boiler room automation project is carried out on the basis of a task drawn up during the implementation of the heat engineering part of the project. The general objectives of monitoring and managing the operation of any power plant are to ensure:

Outputs at every moment required quantity heat at certain parameters of pressure and temperature;

Efficiency of fuel combustion, rational use electricity for the installation’s own needs and to minimize heat losses;

Reliability and safety, i.e. establishing and maintaining normal operating conditions for each unit, excluding the possibility of malfunctions and accidents of both the unit itself and auxiliary equipment.

Based on the tasks and instructions listed above, everything control devices can be divided into five groups intended for measurement:

1. Consumption of water, fuel, air and flue gases.

2. Pressure of water, air gas, measurement of vacuum in elements and gas ducts of the boiler and auxiliary equipment.

3. Water, air and flue gas temperatures

4. Water level in tanks, deaerators and other containers.

5. High-quality composition gases and water.

Secondary devices can be indicating, recording and summing. To reduce the number of secondary devices on the heat shield, some of the values ​​are collected per device using switches; For critical quantities, the maximum permissible values ​​are marked on the secondary device with a red line; they are measured continuously.

In addition to the devices located on the control panel, local installation of control and measuring instruments is often used: thermometers for measuring water temperatures; pressure gauges; various draft meters and gas analyzers.

The combustion process in the KV-TS-20 boiler is controlled by three regulators: a heat load regulator, an air regulator and a vacuum regulator.

The heat load regulator receives a command pulse from the main corrective regulator, as well as pulses for water flow. The heat load regulator acts on the organ that regulates the supply of fuel to the furnace.

The total air regulator maintains the fuel-air ratio by receiving pulses based on fuel consumption from the sensor and the pressure drop in the air heater.

A constant vacuum in the furnace is maintained using a regulator in the boiler furnace and a smoke exhauster acting on the guide vane. There is a dynamic connection between the air regulator and the vacuum regulator, the task of which is to supply an additional impulse in transient modes, which allows you to maintain the correct draft mode during the operation of the air and vacuum regulator.

The dynamic coupling device has directional action, i.e. the slave regulator can only be a discharge regulator.

Power regulators are installed to monitor the consumption of network and feed water.

Mercury expansion thermometer:

Industrial mercury thermometers are made with an embedded scale and, according to the shape of the lower part with the reservoir, there are straight type A and angular type B, bent at an angle of 90º in the direction opposite to the scale. When measuring temperature Bottom part thermometers are completely lowered into the measured medium, i.e. their immersion depth is constant.

Expansion thermometers are indicating instruments located at the point of measurement. Their operating principle is based on the thermal expansion of a liquid in a glass container depending on the measured temperature.

Thermoelectric thermometer:

To measure high temperatures with remote transmission of readings, thermoelectric thermometers are used, the operation of which is based on the principle of the thermoelectric effect. Chromel-copel thermoelectric thermometers develop a thermo-emf that significantly exceeds the thermo-emf of other standard thermoelectric thermometers. The range of application of Chromel - Copel thermoelectric thermometers is from - 50° to + 600° C. The diameter of the electrodes is from 0.7 to 3.2 mm.

Tubular-spring pressure gauge:

Most wide application for measuring overpressure liquid, gas and steam received pressure gauges with simple and reliable design, clarity of indications and small in size. Significant advantages of these devices are also a large measurement range, the possibility of automatic recording and remote transmission of readings.

The operating principle of a deformation pressure gauge is based on the use of elastic deformation sensitive element arising under the influence of the measured pressure.

A very common type of deformation devices used to determine excess pressure are tubular-spring pressure gauges, which play an extremely important role in technical measurements. These devices are made with a single-turn tubular spring, which is a metal elastic tube of oval cross-section bent around a circumference.

One end of the coil spring is connected to the gear, and the other is fixedly mounted on the rack supporting the transmission mechanism.

Under the influence of the measured pressure, the tubular spring partially unwinds and pulls a leash, which sets in motion a gear-sector mechanism and a pressure gauge needle moving along the scale. The pressure gauge has a uniform circular scale with a central angle of 270 - 300°.

Automatic potentiometer:

The main feature of the potentiometer is that it contains the thermoelectric temperature developed by a thermoelectric thermometer. d.s. is balanced (compensated) by a voltage equal in magnitude but opposite in sign from a current source located in the device, which is then measured with great accuracy.

Automatic small-sized potentiometer type KSP2 - an indicating and recording device with a linear scale length and a chart tape width of 160 mm. The main error of the device readings is ±0.5 and the recording error is ±0.1%.

The variation of readings does not exceed half of the main error. The speed of the chart tape can be 20, 40, 60, 120, 240 or 600, 1200, 2400 mm/h.

The potentiometer is powered from the mains alternating current voltage 220 V, frequency 50 Hz. The power consumption of the device is 30 V A. Changing the supply voltage by ±10% of the nominal voltage does not affect the device readings. The permissible ambient temperature is 5 - 50°C and relative humidity is 30 - 80%. Dimensions of the potentiometer are 240 x 320 x 450 mm. and weight 17 kg.

It is recommended to install deformation electric pressure gauges near the pressure tap, securing them vertically with the nipple down. For pressure gauges, the ambient air can have a temperature of 5 - 60°C and a relative humidity of 30 - 95%. They must be removed from powerful sources of alternating magnetic fields (electric motors, transformers, etc.)

The pressure gauge contains a tubular spring 1, fixed in a holder 2 using a bushing 3. A magnetic plunger 5 is suspended from the free end of the spring on a lever 4, located in a magnetomodulation transducer 6 sitting on the holder. Next to the latter, an amplifying device 7 is attached to a folding bracket.

The device is enclosed in a steel case 8 s protective casing 9, suitable for flush mounting. The pressure gauge is connected to the measured pressure using a holder fitting, and the connecting wires are connected via terminal box 10. The pressure gauge is equipped with a zero corrector 11. Dimensions of the device are 212 x 240 x 190 mm. and weight 4.5 kg.

MPE type pressure gauges can be used with one or more secondary devices direct current: automatic electronic indicating and recording milliammeter types KSU4, KSU3,

KSU2, KSU1, KPU1 AND KVU1, graduated in pressure units, magnetoelectric indicating and recording milliammeters of types N340 and N349, central control machines, etc. Automatic electronic DC milliammeters differ from the corresponding automatic potentiometers only by the calibrated load resistor connected parallel to the input, the voltage drop by which from the flowing current of the pressure gauge is the measured quantity.

Magnetoelectric milliammeter types N340 and N349 have a scale and chart width of 100 mm. instrument accuracy class 1.5. The chart tape is driven at a speed of 20 - 5400 mm/h from a synchronous micromotor powered from an alternating current network with a voltage of 127 or 220 V, a frequency of 50 Hz.

Dimensions of the device are 160 x 160 x 245 mm. and weight 5 kg.

Direct acting regulator:

An example of a direct acting regulator is a control valve.

The valve consists of a cast iron body 1, closed at the bottom by a flange cover 2, which closes the hole for draining the medium filling the valve and for cleaning the valve. Stainless steel seats 3 are screwed into the valve body. The plunger 4 sits on the seats. The working surfaces of the plunger are ground into seats 3. The plunger is connected to a rod 6, which can raise and lower the plunger. The rod runs in a stuffing box. The oil seal seals the cover 7, which is attached to the valve body. To lubricate the rubbing surfaces of the rod in stuffing box device Oil is supplied from oiler 5. The valve is controlled by a membrane - lever device, consisting of a yoke 8, a membrane head 13, a lever 1 and weights 16,17. In the membrane head, a rubber membrane 15 is clamped between the upper and lower bowls, resting on a plate 14 mounted on the yoke rod 9. A rod 6 is fixed in the rod 9. The yoke rod has a prism 12, on which a lever 11 rests, rotating on a prism support 10 fixed in the yoke 8.

In the upper bowl of the membrane head there is a hole in which it is fixed impulse tube, delivering a pressure pulse to the membrane. Under the influence of increased pressure, the membrane bends and drags the plate 14 and the yoke rod 9 down. The reinforcement developed by the membrane is balanced by weights 16 and 17 suspended on the lever. Weights 17 serve for rough adjustment of the given pressure. Using a weight 16 moving along the lever, the valve is adjusted more precisely.

The pressure on the membrane head is transmitted directly by the controlled medium.

Actuating mechanism:

Regulating bodies are used to regulate the flow of liquid, gas or steam in a technological process. The movement of regulatory bodies is carried out by actuators.

Regulatory bodies and actuators can be in the form of two separate units connected to each other using levers or cables, or in the form of a complete device, where the regulating body is rigidly connected to the actuator and forms a monoblock.

The actuator, receiving a command from the regulator or from a human-controlled command apparatus, converts this command into mechanical movement of the regulator.

The mechanism is electric, single-turn, designed for moving control elements in relay control systems and remote control. The mechanism receives an electrical command, which is a three-phase mains voltage of 220 or 380 V. The command can be issued using a magnetic contact starter.

The actuator consists of an electric motor part

I - servo drive and control column, II servo drive unit. The servo drive consists of a three-phase asynchronous reversible motor 3 with a squirrel cage rotor. From the motor shaft, the torque is transmitted to gearbox 4, which consists of two stages of a worm gear. Lever 2 is mounted on the input shaft of the gearbox, which is articulated with the regulating body using a rod.

By rotating handwheel 1, with manual control you can rotate the output shaft of the gearbox without the help of an electric motor. By manually operating the flywheel, the mechanical transmission from the electric motor to the flywheel is disconnected.

The regulatory body is designed to change the flow of the regulated medium, energy or any other quantities in accordance with the requirements of the technology.

In poppet valves, the closing and throttling surface is flat. A valve with smooth plug-type working surfaces has a linear characteristic, i.e., the valve capacity is directly proportional to the stroke of the plunger.

Regulation is carried out by changing the flow area by translational movement of the spindle while rotating the flywheel using a lever articulated through a rod with an electric actuator.

Valves cannot serve as shut-off organs.

Control starter:

PMTR-69 starters are made on the basis of magnetic reversing contacts, each of which has three normally open power contacts connected to the power supply circuit of the electric motor. In addition, the starting device has a braking device made on the basis of an electric capacitor and connected through open contacts to one of the stator windings of the electric motor. When any group of power contacts is closed, the auxiliary contacts open and the capacitor is disconnected from the electric motor, moving by inertia, interacts with the residual magnetic field stator and induces emf in its windings.

Auxiliary contacts, closing the circuit of the stator winding of the capacitor, create in the stator the rotor’s own magnetic field and the stator causes a braking effect counteracting rotation, which prevents the actuator from running out. The main disadvantage of starters is low reliability (burning of contacts, short circuit).

The block has three current and one voltage inputs. Block R - 12 consists of the main components: VCC input circuits, DC amplifiers UPT 1 and UPT 2, MO limiting unit, while UPT 2 allows one current signal and an additional voltage signal to be received at the output. Block R - 12 receives power from the power supply unit, which receives an additional signal from the control unit BU.

The signal from the sensor is supplied to the input circuit node, where the signal from the master device I is also supplied. Next, the mismatch signal y goes to the DC amplifier UPT 1, passing through the adder, where mismatch signals from the input circuits and feedback. The OM signal limiting block ensures its further transformation, limiting the signal to a minimum and maximum. Amplifier UPT 2 is the final amplification unit. The MD feedback unit receives a signal from the output of the amplifier UPT 2 and ensures smooth switching of circuits from manual to automatic control. The MD feedback unit ensures the formation of a control signal in accordance with P -, PI - or PID control laws.

Technological protection.

To avoid emergency modes, equipment control systems in the event of excessive deviations of parameters and to ensure operational safety are equipped with technological protection devices.

Depending on the results of the impact on the equipment, protection is divided into: those that stop or shut down units; transferring equipment to reduced load mode; performing local operations and switching; preventing emergency situations.

Protection devices must be reliable in pre-emergency and emergency situations, i.e. there should be no failures or false positives in the protection actions. Failures in the protection actions lead to untimely shutdown of equipment and further development accidents, and false alarms take equipment out of the normal technological cycle, which reduces its operating efficiency. To meet these requirements, highly reliable instruments and devices are used, as well as appropriate protection circuit designs.

The protection includes sources of discrete information: sensors, contact devices, auxiliary contacts, logic elements and a relay control circuit. The activation of protections must ensure unambiguous action, while the equipment is transferred to operating mode after its protection is carried out after checking and eliminating the reasons that caused the operation.

When designing thermal protections for boilers, turbines and other thermal equipment, the so-called priority of protection action is provided, i.e., performing first the operations for the one of the protections that causes a greater degree of unloading. All protections have independent power sources and the ability to record the causes of operation, as well as light and sound alarms.

Technological alarm.

General information about signaling.

The process alarm included in the control system is designed to notify operational personnel about unacceptable deviations of equipment parameters and operating modes.

Depending on the requirements for signaling, it can be divided into several types: signaling, ensuring the reliability and safety of equipment operation; alarm system that records the activation of equipment protections and the reasons for the operation; alarm, notifying about unacceptable deviations of the main parameters and requiring immediate shutdown of the equipment; signaling a fault in the power supply of various equipment and equipment.

All signals are sent to the light and sound devices of the control panel. Sound alarm There are two types: warning (bell) and emergency (siren).

Light signaling are made in a two-color design (red or green lights) or with the help of illuminated panels, which indicate the reason for the alarm.

Newly received signals against the background of those already controlled by the operator may go unnoticed, so signaling circuits are designed so that the new signal is highlighted by blinking.

Functional diagram of the alarm device.

The alarm circuit receives power from a DC power supply, which increases their reliability. The signal to turn on the CB alarm is supplied to the relay signal interruption unit BRP, and then in parallel to the ST light board and the sound device of the charger. At the same time, in the PDU the circuit is designed in such a way that it provides intermittent lighting on the display and a constant sound signal.

After receiving a signal and removing the sound, the circuit must be ready to receive the next signal, regardless of whether the signaling parameter has returned to its nominal value.

Each light signal must be accompanied by a sound to attract the attention of operating personnel.

Signaling means.

Electronic contact pressure gauge.

To measure and signal pressure, an EKM type pressure gauge with a tubular spring is used. The pressure gauge has a body with a diameter of 160 mm. with rear flange and radial fitting. The device contains arrow 1, setting signal arrows 2 and 3 (minimum and maximum), set to specified pressure values ​​using a key. Box 4 with clamps for connecting the alarm circuit to the device. The pressure gauge mechanism is enclosed in housing 5. The device communicates with the medium being measured through fitting 6.

When any of the specified limit pressures are reached, the contact associated with the indicator arrow comes into contact with the contact located on the corresponding signal arrow and closes the alarm circuit. The contact device is powered from a direct or alternating current network, voltage 220 V.

A boiler plant (boiler room) is a structure in which the working fluid (coolant) (usually water) is heated for a heating or steam supply system, located in one technical room. Boiler houses are connected to consumers using heating mains and/or steam pipelines. The main device of a boiler room is a steam, fire tube and/or hot water boiler. Boiler houses are used for centralized heat and steam supply or local heat supply to buildings.

A boiler installation is a complex of devices located in special premises and serving to convert the chemical energy of fuel into thermal energy of steam or hot water. Its main elements are a boiler, a combustion device (furnace), feeding and draft devices. In general, a boiler installation is a combination of boiler(s) and equipment, including the following devices: fuel supply and combustion; purification, chemical preparation and deaeration of water; heat exchangers for various purposes; source (raw) water pumps, network or circulation - for circulating water in the heating system, make-up - to replace water consumed by the consumer and leaks in networks, feed pumps for supplying water to steam boilers, recirculation (mixing); nutrient tanks, condensation tanks, hot water storage tanks; blower fans and air duct; smoke exhausters, gas path and chimney; ventilation devices; systems for automatic regulation and safety of fuel combustion; heat shield or control panel.

A boiler is a heat exchange device in which heat from the hot combustion products of fuel is transferred to water. As a result of this, in steam boilers The water turns into steam and is heated in hot water boilers to the required temperature.

The combustion device is used to burn fuel and convert its chemical energy into heat of heated gases.

Feeding devices (pumps, injectors) are designed to supply water to the boiler.

The draft device consists of blower fans, a gas-air duct system, smoke exhausters and a chimney, which ensure the supply of the required amount of air to the firebox and the movement of combustion products through the boiler flues, as well as their removal into the atmosphere. Combustion products, moving through flues and coming into contact with the heating surface, transfer heat to water.

To provide more economical operation modern boiler systems have auxiliary elements: water economizer and air heater, which serve to heat water and air, respectively; devices for fuel supply and ash removal, for cleaning flue gases and feed water; thermal control devices and automation equipment that ensure normal and uninterrupted operation of all parts of the boiler room.

Depending on the use of their heat, boiler houses are divided into energy, heating and industrial and heating.

Energy boiler houses supply steam to steam power plants that generate electricity, and are usually part of a power plant complex. Heating and industrial boiler houses are located at industrial enterprises and provide heat to heating and ventilation systems, hot water supply to buildings and production processes. Heating boiler houses solve the same problems, but serve residential and public buildings. They are divided into free-standing, interlocking, i.e. adjacent to other buildings, and built into buildings. Recently, more and more often, separate enlarged boiler houses are being built with the expectation of servicing a group of buildings, a residential area, or a microdistrict.

The installation of boiler rooms built into residential and public buildings is currently permitted only with appropriate justification and agreement with the sanitary inspection authorities.

Boiler rooms low power(individual and small group) usually consist of boilers, circulation and make-up pumps and draft devices. Depending on this equipment, the dimensions of the boiler room are mainly determined.

2. Classification of boiler installations

Boiler installations, depending on the nature of consumers, are divided into energy, production and heating and heating. Based on the type of coolant produced, they are divided into steam (for generating steam) and hot water (for producing hot water).

Power boiler plants produce steam for steam turbines in thermal power plants. Such boiler houses are usually equipped with high- and medium-power boiler units that produce steam with increased parameters.

Industrial heating boiler systems (usually steam) produce steam not only for industrial needs, but also for heating, ventilation and hot water supply.

Heating boiler systems (mainly hot water, but they can also be steam) are designed to service heating systems for industrial and residential premises.

Depending on the scale of heat supply, heating boiler houses are local (individual), group and district.

Local boiler houses are usually equipped with hot water boilers that heat water to a temperature of no more than 115 °C or steam boilers with a working pressure of up to 70 kPa. Such boiler houses are designed to supply heat to one or more buildings.

Group boiler systems provide heat to groups of buildings, residential areas or small neighborhoods. They are equipped with both steam and hot water boilers with higher heating capacity than boilers for local boiler houses. These boiler rooms are usually located in specially constructed separate buildings.

District heating boiler houses are used to supply heat to large residential areas: they are equipped with relatively powerful hot water or steam boilers.

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It is customary to conventionally show individual elements of a boiler installation schematic diagram in the form of rectangles, circles, etc. and connect them to each other with lines (solid, dotted), indicating a pipeline, steam lines, etc. B circuit diagrams There are significant differences between steam and hot water boiler plants. A steam boiler plant (Fig. 4, a) consisting of two steam boilers 1, equipped with individual water 4 and air 5 economizers, includes a group ash collector 11, to which the flue gases are approached through a collection hog 12. For suction of flue gases in the area between the ash collector 11 and chimney 9 smoke exhausters 7 with electric motors 8 are installed. To operate the boiler room without smoke exhausters, dampers 10 are installed.

Steam from the boilers through separate steam lines 19 enters the common steam line 18 and through it to the consumer 17. Having given up heat, the steam condenses and returns through the condensate line 16 to the boiler room in the collecting condensation tank 14. Through pipeline 15, additional water from the water supply or chemical water treatment is supplied to the condensation tank (to compensate for the volume not returned from consumers).

In the case when part of the condensate is lost from the consumer, a mixture of condensate and additional water is supplied from the condensation tank by pumps 13 through the supply pipeline 2, first into the economizer 4, and then into the boiler 1. The air required for combustion is sucked in by centrifugal blower fans 6 partially from the room boiler room, partly from the outside and through air ducts 3, it is supplied first to air heaters 5, and then to the boiler furnaces.

The water heating boiler installation (Fig. 4, b) consists of two water heating boilers 1, one group water economizer 5, serving both boilers. Flue gases leaving the economizer through a common collection duct 3 enter directly into the chimney 4. Water heated in the boilers enters the common pipeline 8, from where it is supplied to the consumer 7. Having given off heat, the cooled water through the return pipeline 2 is sent first to the economizer 5 , and then again into the boilers. Water is moved through a closed circuit (boiler, consumer, economizer, boiler) by circulation pumps 6.

Rice. 5. : 1 - circulation pump; 2 - firebox; 3 - steam superheater; 4 - upper drum; 5 - water heater; 6 - air heater; 7 - chimney; 8 - centrifugal fan(smoke exhauster); 9 - fan for supplying air to the air heater

In Fig. Figure 6 shows a diagram of a boiler unit with a steam boiler having an upper drum 12. At the bottom of the boiler there is a firebox 3. To burn liquid or gaseous fuel, nozzles or burners 4 are used, through which the fuel together with air is supplied to the firebox. Boiler limited brick walls- lining 7.

When burning fuel, the heat released heats water to a boil in tube screens 2 installed on the inner surface of the firebox 3 and ensures its transformation into water vapor.

Fig 6.

Flue gases from the furnace enter the boiler flues, formed by lining and special partitions installed in the pipe bundles. When moving, the gases wash the bundles of pipes of the boiler and superheater 11, pass through the economizer 5 and the air heater 6, where they are also cooled due to the transfer of heat to the water entering the boiler and the air supplied to the firebox. Then, the significantly cooled flue gases are removed through the chimney 19 into the atmosphere using a smoke exhauster 17. Flue gases can be removed from the boiler without a smoke exhauster under the influence of natural draft created by the chimney.

Water from the water supply source through the supply pipeline is supplied by pump 16 to the water economizer 5, from where, after heating, it enters the upper drum of the boiler 12. Filling of the boiler drum with water is controlled by water indicator glass installed on the drum. In this case, the water evaporates, and the resulting steam is collected in the upper part of the upper drum 12. Then the steam enters the superheater 11, where due to the heat of the flue gases it is completely dried and its temperature rises.

From the superheater 11, steam enters the main steam line 13 and from there to the consumer, and after use it is condensed and returned to the boiler room in the form of hot water (condensate).

Losses of condensate from the consumer are replenished with water from the water supply or from other water supply sources. Before entering the boiler, water is subjected to appropriate treatment.

The air required for fuel combustion is taken, as a rule, from the top of the boiler room and supplied by fan 18 to air heater 6, where it is heated and then sent to the furnace. In boiler houses of small capacity, there are usually no air heaters, and cold air is supplied to the firebox either by a fan or due to the vacuum in the firebox created by the chimney. Boiler installations are equipped with water treatment devices (not shown in the diagram), control and measuring instruments and appropriate automation equipment, which ensures their uninterrupted and reliable operation.

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For correct installation All elements of the boiler room use a wiring diagram, an example of which is shown in Fig. 9.

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Hot water boiler systems are designed to produce hot water used for heating, hot water supply and other purposes.

To ensure normal operation, boiler rooms with hot water boilers are equipped with the necessary fittings, instrumentation and automation equipment.

A hot water boiler house has one coolant - water, in contrast to a steam boiler house, which has two coolants - water and steam. In this regard, the steam boiler room must have separate pipelines for steam and water, as well as tanks for collecting condensate. However, this does not mean that the circuits of hot water boiler houses are simpler than steam ones. Water heating and steam boiler houses vary in complexity depending on the type of fuel used, the design of the boilers, furnaces, etc. Both steam and water heating boiler systems usually include several boiler units, but not less than two and no more than four or five . All of them are connected by common communications - pipelines, gas pipelines, etc.

The design of lower power boilers is shown below in paragraph 4 of this topic. To better understand the structure and principles of operation of boilers of different power, it is advisable to compare the structure of these less powerful boilers with the structure of the higher power boilers described above, and find in them the main elements that perform the same functions, as well as understand the main reasons for the differences in designs.

3. Classification of boiler units

Boilers like technical devices for the production of steam or hot water are distinguished by a variety of design forms, principles of operation, types of fuel used and production indicators. But according to the method of organizing the movement of water and steam-water mixture, all boilers can be divided into the following two groups:

Boilers with natural circulation;

Boilers with forced movement of coolant (water, steam-water mixture).

In modern heating and heating-industrial boiler houses, boilers with natural circulation are mainly used to produce steam, and boilers with forced movement of coolant operating on the direct-flow principle are used to produce hot water.

Modern steam boilers with natural circulation are made from vertical pipes located between two collectors (upper and lower drums). Their device is shown in the drawing in Fig. 10, photograph of the upper and lower drum with the pipes connecting them - in Fig. 11, and placement in the boiler room is shown in Fig. 12. One part of the pipes, called heated “riser pipes,” is heated by the torch and combustion products, and the other, usually unheated part of the pipes, is located outside the boiler unit and is called “descent pipes.” In heated lifting pipes, water is heated to a boil, partially evaporates and enters the boiler drum in the form of a steam-water mixture, where it is separated into steam and water. Through lowering unheated pipes, water from the upper drum enters the lower collector (drum).

The movement of the coolant in boilers with natural circulation is carried out due to the driving pressure created by the difference in the weights of the water column in the lowering pipes and the column of steam-water mixture in the rising pipes.

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In steam boilers with multiple forced circulation, the heating surfaces are made in the form of coils that form circulation circuits. The movement of water and steam-water mixture in such circuits is carried out using a circulation pump.

In direct-flow steam boilers, the circulation ratio is unity, i.e. The feed water, when heated, successively turns into a steam-water mixture, saturated and superheated steam.

In hot water boilers, water moving along the circulation circuit is heated in one revolution from the initial to the final temperature.

Based on the type of coolant, boilers are divided into hot water and steam boilers. The main indicators of a hot water boiler are thermal power, that is, heating output, and water temperature; The main indicators of a steam boiler are steam output, pressure and temperature.

Hot water boilers, the purpose of which is to obtain hot water of specified parameters, are used for heat supply to heating and ventilation systems, household and technological consumers. Hot water boilers, usually operating on the direct-flow principle with a constant flow of water, are installed not only at thermal power plants, but also in district heating, as well as heating and industrial boiler houses as the main source of heat supply.

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Based on the relative movement of heat-exchanging media (flue gases, water and steam), steam boilers (steam generators) can be divided into two groups: water-tube boilers and fire-tube boilers. In water-tube steam generators, water and a steam-water mixture move inside the pipes, and flue gases wash the outside of the pipes. In Russia in the 20th century, Shukhov water-tube boilers were mainly used. In fire tubes, on the contrary, flue gases move inside the pipes, and water washes the pipes outside.

Based on the principle of movement of water and steam-water mixture, steam generators are divided into units with natural circulation and with forced circulation. The latter are divided into direct-flow and multiple-forced circulation.

Examples of placement of boilers of different capacities and purposes, as well as other equipment, in boiler rooms are shown in Fig. 14-16.

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Rice. 16. Examples of placement of household boilers and other equipment

Section Contents

Combined drumless steam and hot water boilers differ from conventional drum steam boilers low pressure and steel direct-flow water heating boilers in that they can operate in three different modes: pure water heating, combined with the simultaneous delivery of hot water and low-pressure water steam, and pure steam, when all heating surfaces of the combined boiler operate as evaporative ones. In this case, all screen surfaces of the combustion chamber and the rear screen of the convective shaft are converted into drumless steam circuits with natural circulation.

Convection packages with horizontal tube bundles and side screens of the convection shaft work as evaporative steam circuits with multiple forced circulation. Transferring a combination boiler from one operating mode to another requires a short stop of the boiler to remove and install plugs on the corresponding water bypass pipes of the water heating circuit, as well as on the connecting pipes of the steam evaporation circuits. Instead of plugs, the installation of water and steam valves with remote switching on and off from the central control panel had to be abandoned, since the practice of their use has shown that the valves do not provide the proper density and allow an unacceptable flow of medium from one circuit to another.

The general objectives of monitoring and managing the operation of a combined boiler are to ensure the production at any given moment of the required amount of heat in the form of hot water and steam at certain parameters - pressure and temperature, as well as ensuring the efficiency of fuel combustion, rational use of electricity for own needs and minimizing heat loss. The reliable operation of the boiler and its auxiliary equipment must also be ensured.

Operating personnel must always have a clear understanding of the operating mode of the entire unit according to the readings of instrumentation.

These devices can be divided into five groups according to the types of measurements:

a) consumption of steam, water, fuel, sometimes air, flue gases;

b) pressures of steam, water, gas, fuel oil, air and vacuum in the boiler flues;

c) temperatures of steam, water, fuel, air and flue gases;

d) water level in the boiler steam circuit, cyclones, tanks, deaerators, fuel level in bunkers and other containers;

e) the composition of flue gases, as well as the quality of steam and water.

Almost all instrumentation consists of a receiving part (sensor), a transmitting part and a secondary device, which is used to read the measured value. Secondary devices can be indicating, recording (recording) and summing (counters). To reduce the number of secondary devices on the heat shield, some of the values ​​are collected onto one secondary device using switches. On the secondary device, for critical quantities, the maximum permissible values ​​​​of the operating parameters of the combined boiler are marked with a red line (pressure of water, steam, water heating, etc.).

Responsible quantities are measured continuously, and the rest - periodically.

When choosing the number of devices and their placement, they are guided by the rules of Gosgortekhnadzor for boiler units, gas supervision rules, departmental rules such as rules technical operation And building codes and rules (SNiP), which regulate a number of measurements necessary for personnel safety and accounting.

The general principle when choosing a location for installing devices is ease of maintenance of the unit. minimum number people with low capital and operating costs for devices. Therefore, when developing a boiler house project of any capacity, a diagram, drawings and estimates for the installation of instruments and automation devices are completed. The costs of instrumentation should not exceed a few percent of the total cost of the boiler installation.

Typically, automation systems are designed in such a way that the part of the control and measuring device that perceives changes in any magnitude serves as a pulse sensor for the automatic control system. Electromotive force thermoelectric converter, a change in vacuum in the furnace or behind the unit, a change in pressure in the boiler unit and other quantities are used as impulses entering the regulator. The latter, receiving impulses, algebraically sums them up, amplifies and sometimes converts them, and then transmits them to the controls. In this way, automation of the installation is combined with control of its operation.

In addition to the instruments displayed on the control panel, local installation of instrumentation is often used (thermometers for measuring the temperature of water, steam, fuel oil, pressure gauges and vacuum gauges for measuring pressure and vacuum, various draft meters and gas analyzers). Devices are needed not only for correct operation unit, but also for periodic tests carried out after repair or reconstruction.

Installed for monitoring proper work and safe operation of boilers, are conditionally divided into two main categories: indicating and recording

showing is used when periodic recording of the boiler operating mode is allowed. Recording instruments are used to constantly determine the operating parameters of the unit or for any period of time.

All both indicating and recording instrumentation are installed on the boiler control panel, convenient for monitoring their indicators that determine the operating mode of the boiler

Instrumentation is used for systematic monitoring of the following quantities and parameters of the boiler:

temperature and pressure of superheated steam at the outlet;

steam pressure in the boiler and the temperature of the water supplying the boiler;

water level in the boiler;

the amount of water entering the boiler and the amount of steam produced;

vacuum in the firebox and in front of the fire chamber;

temperature and air pressure before and after air heating;

To measure excess pressure, use various designs pressure gauges, the dial of which must be in a vertical plane or tilted forward up to 30 °. A red line is drawn on the pressure gauge dial behind the pressure, corresponding to the highest permissible operating pressure for a particular boiler unit. Pressure gauges must undergo a control check every 6 months, be in good working order and sealed.

Why is automatic control of boiler units introduced?

Automatic control of the boiler unit is introduced to regulate thermal processes and maintain specified quantitative and qualitative indicators of the production process

To generate steam, an appropriate amount of fuel, water and air is required, which must correspond to the volume of production and change along with changes in steam consumption

Automatic safety allows you to automatically change the mode of supply of fuel, air and water. When the operating mode changes or malfunctions of individual boiler devices, the gas supply to the alniq is automatically turned off.

The main safety elements are safety valves. They are automatically triggered if the pressure in the boiler rises above the permissible level

According to the principle of operation, safety valves are classified as lever-weight, lever-spring and spring; by design - open or closed. They are installed on the boiler in pairs or individually equipped with devices that protect personnel from burns when they are triggered, as well as signaling devices for giving a signal when the bet is released.

The automation provides special starting devices for the safe ignition of boilers, which allow gas to be supplied into the gas pipeline only if there is a flame in the furnace in front of the working burners, and the valves in front of the burners and at the discharge to the atmosphere are closed.

Automatic safety controls the combustion process and heating of water in the boiler. In case of violation normal operation boiler and its parameters, control devices act on the safety system and turn off. Turning off the gas supply to the boiler.

Before putting boiler units into operation, automation devices must be checked and adjusted in accordance with the specified operating mode

What applies to boiler installation fittings?

In accordance with safety requirements, fittings are installed on all boilers with a steam output of 2 t/h and above, which include water level indicators that control the water level. Water level indicators are connected to the boiler using the upper and lower pipes, which are included in the steam and water space.

A sign with the inscription “Lower water level” is installed on water indicating devices. It must be 50 mm below the normal level and no less than 25 mm above the lower visible level. Glass edges

The "Upper water level" indicator is installed 50 mm above the normal level in the boiler and no less than 25 mm below the upper visible edge of the glass

In addition to the above, boilers are equipped with automatic sound and light alarms for the upper and lower water levels, as well as safety devices that automatically stop the heat supply to the boiler when low or high level water or high steam pressure.

State Register No. 25264-03. Certificate of the State Standard of the Russian Federation on type approval SI No. 15360 dated July 16, 2003.
Verification method MI2124-90, verification interval 2 years.

Deformation pressure gauges Type DM 02
The body is painted steel (black), the mechanism is brass.
Instrument glass, radial fitting (down).
Temperature of the measured medium up to +160°С (for a diameter of 63 mm up to +120°С).

There are also vacuum gauges and pressure and vacuum gauges. On high pressure by order.

Deformation pressure gauges Type DM 15
Axial (fitting in the rear center).
Execution type DM02.
Temperature of the measured medium up to +120°C.

Deformation pressure gauges Type DM 90
Stainless steel case and mechanism, instrument glass.
The fitting is radial (down).
Temperature of the measured medium up to +160°С.

Deformation pressure gauges Type DM 93
Stainless steel case, brass mechanism, polycarbonate glass.
Hydraulic filling of the body with glycerin, radial fitting (down).
Temperature of the measured medium up to +60°С.

Vacuum gauges and pressure-vacuum gauges. 3-way brass valves for pressure gauges

We also supply:
Vacuum gauges and pressure-vacuum gauges
3-way brass valves for pressure gauges
from 78 rub. (made in Italy) PN 16 temp. up to +150°С.
State checking pressure gauges increases the cost by 45 rubles. per piece
Performed at the customer's request. The verification period is 3-10 working days.

are designed to measure the pressure of various media and control external electrical circuits from a direct-acting signaling device by turning on and off contacts in signaling, automation and blocking circuits of technological processes.

Water indicator equipment for boilers

Liquid level indicators 12kch11bkused in steam boilers, vessels, apparatus, liquid tanks with Ru25 and t=250 degrees. C and other liquid non-aggressive media, steam and ethyl mercaptan.
Body material: malleable cast iron - KCh30-6.
The pointer consists of a body, a cover, an upper and lower tube and an index glass. The reflection and refraction of light rays in the glass edges provides an indication of the level of the liquid, which takes on a dark tint.
The connection between the cover and the body is bolted.

Drawing and dimensions:

Specifications:

consist of lower and upper taps. Quartz glass tubes are also used as a level indicator.

Specifications:

Quartz glass tubes

Clear Quartz Glass Tubesused for measuring liquid levels, for electric heating devices, for various instruments and devices and are designed to operate at temperatures up to 1250 o C.
Tubes intended for installation in taps of shut-off devices for liquid level indicators must have an outer diameter of 20 mm and withstand a maximum pressure of 30 kgf/cm 2 . The ends of the tubes are cut and ground before installation.

Main tube sizes:

Physical properties of quartz glass

Quartz glass has a number of unique properties, unattainable for other materials.
Its coefficient of thermal expansion is extremely low.
The transformation point and softening temperature of quartz are very high.
On the other hand, quartz's low coefficient of thermal expansion gives it unusually high heat resistance.
The electrical resistance of quartz is significantly higher than that of the best silicate glasses. This makes quartz an excellent material for the manufacture of heat-operated insulating elements.

Porthole viewing glassesflat are intended for windows of industrial installations and observation lights.
Viewing windowsare designed for visual monitoring of the presence of a flow of various media in technological processes of the food, chemical, oil refining, construction and other industries.
Also, these glasses (untempered) are used by astronomers as blanks for mirrors.

Glass is divided into:

according to composition and manufacturing method:

• type A - non-tempered sheet glass,
• type B - tempered sheet glass,
• type B - tempered from heat-resistant glass (produced since 01/01/91, at the moment practically not produced),
• type G - made of quartz glass;

according to form:

• round (types A, B, C, D),
• rectangular (type A).

Glass diameters - from 40 to 550 mm, standard thicknesses: 8, 6, 10, 12, 15, 18, 20, 25 mm.