Control and measuring instruments for steam and water heating boilers. What control and measuring instruments are equipped with boiler units? Indirect acting regulators

Instrumentation and automation (instrumentation and automation) are designed to measure, control and regulate temperature, pressure, water level in the drum and provide safe work heat generators and heat power equipment of the boiler room.

1. Temperature measurement.

To measure the temperature of the working fluid, manometric and mercury thermometers are used. A stainless steel sleeve is welded into the pipeline, the end of which should reach the center of the pipeline, it is filled with oil and a thermometer is lowered into it.

Manometric thermometer consists of a thermal bulb, a copper or steel tube and a tubular spring of oval cross-section, connected by a lever transmission with an indicating arrow.

Rice. 3.1. Manometric thermometer

1-thermal cylinder; 2-connection capillary; 3-thrust; 4-arrow; 5-dial; 6-gauge spring; 7-tribe-sector mechanism

The entire system is filled with inert gas (nitrogen) under a pressure of 1...1.2 MPa. As the temperature rises, the pressure in the system increases, and a spring moves the needle through a system of levers. Indicating and self-recording pressure gauge thermometers are stronger than glass thermometers and allow readings to be transmitted over a distance of up to 60 m.

Action resistance thermometers– platinum (TSP) and copper (TCM) based on the use of the dependence electrical resistance substances depending on temperature.

Rice. 3.2. Resistance thermometers platinum, copper

Action thermoelectric thermometer based on the use of the dependence of the thermoEMF of a thermocouple on temperature. A thermocouple, as a sensitive element of a thermometer, consists of two dissimilar conductors (thermoelectrodes), one end of which (working) is connected to each other, and the other (free) is connected to the measuring device. At different temperatures of the working and free ends, an emf appears in the circuit of a thermoelectric thermometer.

Most widespread have thermocouples of the TXA (chromel-alumel) and THK (chromel-kopel) types. Thermocouple for high temperatures placed in a protective (steel or porcelain) tube, Bottom part which is protected by a cover and a lid. Thermocouples have high sensitivity, low inertia, and the ability to install recording instruments on long distance. The thermocouple is connected to the device using compensation wires.

2. Pressure measurement.

To measure pressure, barometers, pressure gauges, vacuum gauges, draft gauges, etc. are used, which measure barometric or excess pressure, as well as vacuum in mm of water. Art., mm Hg. Art., m water. Art., MPa, kgf/cm2, kgf/m2, etc. To control the operation of the boiler furnace (when burning gas and fuel oil), the following devices can be installed:

1) pressure gauges (liquid, membrane, spring) - show the fuel pressure on the burner after the operating valve;

Rice. 3.3. Strain gauges:

1 - membrane; 2 - active and compensating strain gauge; 3 - console; 4-arrow

2) pressure gauges (U-shaped, membrane, differential) - show the air pressure on the burner after the control valve;

3) draft meters (TNZh, membrane) - show the vacuum in the firebox.

Liquid thrust gauge(TNZh) is used to measure low pressures or vacuums.

Rice. 3.4. Thrust pressure meter type TNZh-N

To obtain more accurate readings, draft meters with an inclined tube are used, one end of which is lowered into a vessel of large cross-section, and alcohol (density 0.85 g/cm 3) tinted with magenta is used as the working fluid. The can is connected with the “+” fitting to the atmosphere (barometric pressure), and alcohol is poured through the fitting. Glass tube The “−” fitting (vacuum) is connected to the rubber tube and the boiler firebox. One screw sets the “zero” of the tube scale, and the other sets the horizontal level on the vertical wall. When measuring vacuum, the impulse tube is connected to the “−” fitting, and barometric pressure is connected to the “+” fitting.

Spring pressure gauge designed to indicate pressure in vessels and pipelines and is installed in a straight section. The sensitive element is a brass oval-curved tube, one end of which is mounted in a fitting, and the free end, under the influence of the pressure of the working fluid, is straightened (due to the difference in the internal and external areas) and, through a system of traction and a gear sector, transmits force to a pointer mounted on the gear. This mechanism is located in

case with a scale, covered with glass and sealed. The scale is selected so that at operating pressure the pointer is in the middle third of the scale. The scale should have a red line indicating the permissible pressure.

IN electrical contact pressure gauges The ECM has two fixed fixed contacts on the scale, and a moving contact on the working pointer.

Rice. 3.5. Pressure gauge with electrical contact attachment TM-610

When the arrow touches a fixed contact, an electrical signal from them is sent to the control panel and the alarm is activated. A three-way valve must be installed in front of each pressure gauge for purging, checking and shutting it off, as well as a siphon tube (hydraulic seal filled with water or condensate) with a diameter of at least 10 mm to protect the internal mechanism of the pressure gauge from exposure to high temperatures. When installing a pressure gauge at a height of up to 2 m from the level of the observation platform, the diameter of its body must be at least 100 mm; from 2 to 3 m – at least 150 mm; 3…5 m – not less than 250 mm; at a height of more than 5 m, a reduced pressure gauge is installed. The pressure gauge must be installed vertically or tilted forward at an angle of up to 30° so that its readings are visible from the level of the observation platform, and the accuracy class of the pressure gauges must be at least 2.5 - at pressures up to 2.5 MPa and not below 1, 5 – from 2.5 to 14 MPa.

Pressure gauges are not allowed for use if there is no seal (stamp) or the inspection period has expired, the needle does not return to zero on the scale (when the pressure gauge is turned off), the glass is broken or there is other damage. The seal or mark is installed by Gosstandart during inspection once a year.

Checking the pressure gauge should be carried out by the operator upon each shift acceptance, and by the administration at least once every 6 months using a control pressure gauge. The pressure gauge is checked in the following sequence:

1) visually notice the position of the arrow;

2) use the handle of a three-way valve to connect the pressure gauge to the atmosphere - the arrow should go to zero;

3) slowly turn the knob to its previous position - the arrow should return to its previous (before checking) position;

4) turn the tap handle clockwise and put it in a position in which the siphon tube will be connected to the atmosphere - for purging; 5) turn the tap handle to reverse side and set it for a few minutes in a neutral position, in which the pressure gauge will be disconnected from the atmosphere and from the boiler - to accumulate water in the lower part of the siphon tube;

6) slowly turn the tap handle in the same direction and return it to its original position working position– the arrow should return to its original place.

To check the accuracy of the pressure gauge readings, a control (model) pressure gauge is attached to the control flange with a bracket, and the valve handle is placed in a position in which both pressure gauges are connected to the space under pressure. A working pressure gauge should give the same readings as the control pressure gauge, after which the results are recorded in the control check log.

Pressure gauges must be installed on boiler room equipment:

1) in a steam boiler unit - heat generator: on the boiler drum, and if there is a superheater - behind it, to the main valve; on the supply line in front of the valve that regulates the water supply; on the economizer - water inlet and outlet to the shut-off valve and safety valve; on

water supply network - when using it;

2) in a water heating boiler unit - heat generator: at the water inlet and outlet up to the shut-off valve or gate valve; on the suction and discharge lines of circulation pumps, located at the same height; on heating supply lines. On steam boilers with a steam output of more than 10 t/h and hot water boilers with a heating output of more than 6 MW, the installation of a recording pressure gauge is required.

3. Water indicating devices.

When a steam boiler is operating, the water level fluctuates between the lowest and highest positions. The lowest permissible level (LAL) of water in the drums of steam boilers is set (determined) to eliminate the possibility of overheating of the metal walls of the boiler elements and to ensure reliable flow of water into the downpipes of the circulation circuits. The position of the highest permissible level (HPL) of water in the drums of steam boilers is determined from the conditions for preventing water from entering the steam pipeline or superheater. The volume of water contained in the drum between the highest and lower levels, determines the “power supply”, i.e. time allowing the boiler to operate without water entering it.

Each steam boiler must be equipped with at least two water level indicators direct action. Water indicators should be installed vertically or tilted forward, at an angle of no more than 30°, so that the water level is clearly visible from the workplace. Water level indicators are connected to the upper drum of the boiler using straight pipes up to 0.5 m long and an internal diameter of at least 25 mm or more than 0.5 m and an internal diameter of at least 50 mm.

In steam boilers with pressures up to 4 MPa, water-indicating glass (VUS) is used - devices with flat glass with a corrugated surface, in which the longitudinal grooves of the glass reflect light, making the water appear dark and the steam light. The glass is inserted into a frame (column) with a viewing slit width of at least 8 mm, on which the permissible upper water level and lower water level must be indicated (in the form of red arrows), and the height of the glass must exceed the permissible measurement limits by at least 25 mm with each side. The NDU arrow is installed 100 mm above the boiler firing line.

Fire line- this is the highest point of contact between hot flue gases with a non-insulated boiler element wall.

Water indicating devices for disconnecting them from the boiler and carrying out purging are equipped with shut-off valves(taps or valves). The fittings must be clearly marked (cast, embossed or painted) in the direction of opening or closing, and the internal diameter of the passage must be at least 8 mm. To drain water during purging, a double funnel with protective devices and an outlet pipe for free drainage are provided, and a purge valve is installed on the boiler fire line.

The boiler room operator must check the water indicator glass using the blowing method at least once per shift, for which he should:

1) make sure that the water level in the boiler has not dropped below the minimum level;

2) visually notice the position of the water level in the glass;

3) open the purge valve - the steam and water valves are purged;

4) close the steam valve, blow out the water valve;

5) open the steam tap - both taps are purged;

6) close the water tap, blow out the steam;

7) open the water tap - both taps are ventilated;

8) close the purge valve and observe the water level, which should rise quickly and fluctuate around the previous level if the glass was not clogged.

Do not close both taps while the purge tap is open, as the glass will cool down and may burst if hot water hits it. If, after blowing, the water in the glass rises slowly or has occupied a different level, or does not fluctuate, then it is necessary to repeat the blowing, and if repeated blowing does not produce results, it is necessary to clean the clogged channel.

A sharp fluctuation of water characterizes abnormal boiling due to the increased content of salts, alkalis, sludge or the extraction of steam from the boiler more than it is produced, as well as the combustion of soot in the boiler flues.

A slight fluctuation in the water level characterizes partial “boiling” or clogging of the water tap, and if the water level is higher than normal, “boiling” or clogging of the steam tap. When the steam tap is completely clogged, the steam above the water level condenses, causing water to completely and quickly fill the glass to the very top. If the water tap is completely clogged, the water level in the glass will slowly rise due to steam condensation or will take a calm level, the danger of which is that, without noticing fluctuations in the water level and seeing it in the glass, you might think that there is enough water in the boiler.

It is unacceptable to increase the water level above the air pressure limit, as water will flow into the steam line, which will lead to water hammer and rupture of the steam line.

When the water level drops below the NDU, it is strictly forbidden to feed the steam boiler with water, since in the absence of water the metal of the boiler walls becomes very hot, becomes soft, and when water is supplied to the boiler drum, strong steam formation occurs, which leads to a sharp increase in pressure, thinning of the metal, the formation of cracks and pipe rupture.

If the distance from the water level observation site is more than 6 m, as well as in case of poor visibility (lighting) of the instruments, two lowered remote level indicators must be installed; in this case, one direct-acting VUS can be installed on the boiler drums. Reduced level indicators must be connected to the drum on separate fittings and have a damping device.

4. Measuring and regulating the water level in the drum.

Diaphragm differential pressure gauge(DM) is used for proportional control of the water level in drum steam boilers.

Rice. 3.6. Diaphragm indicating differential pressure gauge with vertical diaphragm

1 - “plus” camera; 2 - “minus” camera; 5 - sensitive corrugated membrane; 4- transmitting rod; 5 - transmission mechanism; 6 - safety valve and, accordingly, an index arrow, indicating the measured pressure on the instrument scale

The pressure gauge consists of two membrane boxes communicating through a hole in the diaphragm and filled with condensate. The lower membrane box is installed in the positive chamber filled with condensate, and the upper one is installed in the negative chamber filled with water and connected to the measured object (the upper drum of the boiler). The core of the induction coil is connected to the center of the upper membrane. At an average water level in the boiler drum, there is no pressure drop and the membrane boxes are balanced.

As the water level in the boiler drum increases, the pressure in the minus chamber increases, the membrane box contracts, and the liquid flows into the lower box, causing the core to move downward. In this case, an EMF is generated in the coil winding, which sends a signal through the amplifier to the actuator and closes the valve on the supply line, i.e. reduces the flow of water into the drum. When the water level drops, the DM operates in the reverse order.

Level column The control unit is designed for positional control of the water level in the boiler drum.

Rice. 3.7. Level column UK-4

It consists of a cylindrical column (pipe) with a diameter of about 250 mm, in which four electrodes are installed vertically, capable of controlling the highest and lowest permissible water levels (VDU and NDU), the highest and lowest operating water levels in the drum (ARU and NRU), the operation of which based on the electrical conductivity of water. The column is connected on the side to the steam and water volume of the boiler drum using pipes with taps. At the bottom of the column there is a purge valve.

When the water level of the ASU is reached, the relay is turned on and the contactor breaks the power circuit of the magnetic starter, turning off the feed pump drive. The water supply to the boiler stops. The water level in the drum decreases, and when it drops below the NRU, the relay is de-energized and the feed pump is turned on. When the water level of the VDU and NDU is reached, an electrical signal from the electrodes goes through the control unit to the fuel supply cutoff to the firebox.

5. Instruments for measuring flow.

Flow meters are used to measure the flow of liquids (water, fuel oil), gases and steam:

1) high-speed volumetric, measuring the volume of liquid or gas by flow velocity and summing up these results;

2) throttling, with variable and constant differential pressure or rotameters.

In the working chamber high-speed volumetric flow meter(water meter, oil meter) a vane or spiral turntable is installed, which rotates from the liquid entering the device and transmits the flow rate to the counting mechanism.

Volumetric rotary counter(RG type) measures the total gas flow rate up to 1000 m 3 / h, for which two mutually perpendicular rotors are placed in the working chamber, which are driven into rotation under the influence of the pressure of the flowing gas, each revolution of which is transmitted through gears and a gearbox to the counting mechanism.

Throttle flow meters with a variable pressure drop have restriction devices - normal diaphragms (washers) chambered and tubeless with a hole smaller than the cross-section of the pipeline.

When a flow of medium passes through the hole of the washer, its speed increases, the pressure behind the washer decreases, and the pressure difference before and after the throttling device depends on the flow rate of the measured medium: the greater the amount of substance, the greater the difference.

The pressure difference before and after the diaphragm is measured by a differential pressure gauge, from the measurements of which the speed of fluid flow through the washer hole can be calculated. A normal diaphragm is made in the form of a disk (made of stainless steel) 3...6 mm thick with a central hole having a sharp edge, and should be located on the liquid or gas inlet side and installed between the flanges on a straight section of the pipeline. The pressure pulse to the differential pressure gauge is produced through holes from the annular chambers or through an hole on both sides of the diaphragm.

To measure steam flow on impulse tubes, equalizing (condensation) vessels are installed to the differential pressure gauge, designed to maintain constant condensate levels in both lines. When measuring gas flow, the differential pressure gauge should be installed above the restriction device so that the condensate formed in the impulse tubes can drain into the pipeline, and the impulse tubes along the entire length should have a slope towards the gas pipeline (pipeline) and be connected to the upper half of the washer. Calculation of diaphragms and installation on pipelines is carried out in accordance with the rules.

6. Gas analyzers are designed to monitor the completeness of fuel combustion, excess air and determine the volume fraction in combustion products carbon dioxide, oxygen, carbon monoxide, hydrogen, methane.

Based on their operating principle, they are divided into:

1) chemical(GHP, Orsa, VTI), based on the sequential absorption of gases included in the analyzed sample;

2) physical, operating on the principle of measuring physical parameters (density of gas and air, their thermal conductivity);

3) chromatographic, based on the adsorption (absorption) of the components of a gas mixture with a certain adsorbent (activated carbon) and their sequential desorption (release) as they pass through a column with an adsorbent gas.

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 plant is a complex of devices located in special rooms and used to transform chemical energy 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 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 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, water is converted into steam in steam boilers, and heated to the required temperature in hot water boilers.

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 ensures the supply required quantity air into the furnace 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 ensure more economical operation, modern boiler systems have auxiliary elements: a water economizer and an 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 found in industrial enterprises and provide heat for 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 an operating 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.

Rice. 1.

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Rice. 3.

Rice. 4.

Individual elements It is customary to conventionally show a schematic diagram of a boiler installation in the form of rectangles, circles, etc. and connect them to each other with lines (solid, dotted), indicating a pipeline, steam lines, etc. There are significant differences in the basic diagrams of steam and water heating 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. The boiler is limited by 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.

Figure 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 a 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 it 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.

Rice. 7.

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

Rice. 9.

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 as 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 natural circulation steam boilers are made of 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.

Rice. 10.

Rice. eleven.

Rice. 12.

In steam boilers with multiple forced circulation 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 capacity, 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.

Rice. 13.

Rice. 14.

Based on the relative movement of heat exchange 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.

Rice. 15.

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

Modern thermal power engineering cannot be imagined without high-precision measuring instruments. The technological process at energy facilities must be constantly monitored using sensors or converters that not only passively receive information, but also allow automatic adjustment and protective shutdown in the event of a violation of normal operation.

Types of instrumentation and automation in a boiler room

From common name and the above, we can conclude that for trouble-free operation gas equipment the following complexes are required:

• measuring;
• adjusting;
• protective.

The operation of water heating and power plants without protective devices is prohibited, since non-standard situations and breakdowns, the threat to human life and the integrity of mechanisms increases many times over. Before lighting, the duty personnel will check the operation of the protection to stop the boiler. The introduction of this clause in the PTE helped to seriously reduce the negative consequences of accidents.

Peculiarities instrumentation and automation work boiler equipment

For network and gas pipelines Both remote digital systems and on-site mechanical devices are provided. This allows service personnel to monitor the state of the environment while touring the boiler room or in the event of a power loss. The protection most often applies to the fuel supply, to prevent an explosion in the event of violations of the combustion regime in boilers.

Maintenance of instrumentation and automation in boiler rooms

For proper operation control devices at thermal power engineering facilities form a special workshop or division. This service performs the following functions:

• daily monitoring of the accuracy of readings,
• checking protection devices;
• repair and replacement of failed devices;
• periodic verification of measuring devices.

Maintaining the boiler unit mode is impossible without constant monitoring by the boiler room operator. Several rounds per shift help keep such measuring equipment in good working order.

Instrumentation and automation devices for boiler rooms

The main measuring devices in gas boiler houses are:

• Pressure gauges. Necessary for monitoring pressure in pipelines; without them, operation is often impossible. They are used to regulate the combustion process in water heating and energy boilers, by measuring pressures natural gas and air.
• Thermocouples. The coolant must be supplied to the city at a certain temperature. To control it, and therefore the operating mode of the boiler room, several thermal converters are installed.
• Flow meters. Economic characteristics production of thermal and electrical energy associated with the costs of the working environment and fuel. Digital recording devices are used to measure them.

Instrumentation and automation mechanic for gas boiler houses

IN modern production all parameters received from measuring instruments are accumulated at the point. Computer systems it allows you to access this information up to a certain period. This order is useful for analysis.

The responsibilities of the duty mechanic include general items:

• ensuring the serviceability of control and protection devices;
• periodic checking of measuring instruments;
• instrumentation and automation maintenance in the boiler room;
• accumulation and provision of comprehensive information on the parameters of the production process.

Operating personnel take shifts to ensure the normal operation of measuring systems at energy facilities and heating networks. He also monitors the information collection system to prevent failures.

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. Common tasks control and management of any work power plant is to ensure:

Generating at each moment the required amount of heat at certain parameters of pressure and temperature;

Efficiency of fuel combustion, rational use electricity for own needs installation and minimization of heat loss;

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 the elements and gas ducts of the boiler and auxiliary equipment.

3. Temperatures of water, air and flue gases

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

5. Qualitative composition of 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 with a red line on the secondary device; 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 maintaining 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 manufactured with an embedded scale and, according to the shape of the lower part with a reservoir, they are straight type A and corner type B, bent at an angle of 90º in the direction opposite to the scale. When measuring temperature, the lower part of the thermometers is completely lowered into the medium being measured, 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. Electrode diameter is from 0.7 to 3.2 mm.

Tubular-spring pressure gauge:

The most widely used for measuring excess pressure of liquid, gas and steam are pressure gauges that have a simple and reliable design, clarity of indications and small in size. Significant advantages of these devices are also a large measurement range, the ability automatic recording and remote transmission of readings.

The operating principle of a deformation pressure gauge is based on the use of deformation of an elastic sensing element that occurs 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 a 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 central angle 270 - 300є.

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 by an AC voltage of 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. Permissible value ambient temperature 5 - 50°C and relative humidity 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 relative humidity 30 - 95%. They must be removed from powerful sources 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 amplification 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, calibrated in pressure units, magnetoelectric indicating and recording milliammeters of types N340 and N349, central control machines, etc. Automatic electronic direct current 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, oil is supplied to the stuffing box 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, between the upper and lower bowls, a rubber membrane 15 is clamped, 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 an impulse tube is fixed, supplying a pressure pulse to the membrane. Under the influence of increased pressure, the membrane bends and drags plate 14 and 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 to move control elements in relay control and remote control systems. 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 of the stator and induces an 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: input circuits VCC, DC amplifiers UPT 1 and UPT 2, limiting unit MO, while UPT 2 allows you to receive one current signal and an additional voltage signal 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 are generated. 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 block 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 must be no failures or false alarms in the protection actions. Failures in the protection actions lead to untimely shutdown of equipment and further development of the accident, and false alarms take the equipment out of normal operation. technological cycle, which reduces its efficiency. To meet these requirements, highly reliable instruments and devices are used, as well as appropriate protection circuits.

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 causes that caused the operation.

When designing thermal protection of boilers, turbines and other thermal equipment provide for the so-called priority of protection action, i.e., performing first of all 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, which is part of the control system, is designed to notify operating personnel about unacceptable deviations in the parameters and operating mode of the equipment.

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 alarms are made in a two-color design (red or green lights) or using 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.

In heating boiler houses operating on gas and liquid fuel, complex control systems are used, each of which, depending on the purpose and power of the boiler room, gas pressure, type and parameters of the coolant, has its own specifics and scope.

Main requirements for boiler room automation systems:
— ensuring safe operation
— optimal regulation of fuel consumption.

An indicator of the perfection of the applied control systems is their self-control, i.e. giving a signal about emergency stop boiler room or one of the boilers and automatic recording of the reason that caused the emergency shutdown.
A number of commercially produced control systems allow for semi-automatic start and stop of boiler units operating on gas and liquid fuel. One of the features of automation systems for gasified boiler houses is complete control over the safety of equipment and units. The system of special protective interlocks must ensure that the fuel supply is turned off when:
— violation of the normal sequence of starting operations;
— turning off the blower fans;
— a decrease (increase) in gas pressure below (above) the permissible limit;
— violation of draft in the boiler furnace;
— failures and extinguishing of the torch;
— loss of water level in the boiler;
— other cases of deviation of the operating parameters of boiler units from the norm.
Respectively modern systems controls consist of instruments and equipment that provide comprehensive regulation of the regime and the safety of their operation. The implementation of complex automation involves a reduction in service personnel depending on the degree of automation. Some of the control systems used contribute to the automation of all technological processes in boiler rooms, including the remote mode of boilers, which allows you to control the operation of boiler rooms directly from the control center, while the personnel are completely removed from the boiler rooms. However, dispatching boiler houses requires a high degree of operational reliability. executive bodies and sensors of automation systems. In some cases, they are limited to the use of “minimum” automation in boiler rooms, designed to control only basic parameters (partial automation). A number of technological requirements are imposed on manufactured and newly developed control systems for heating boiler houses: aggregation, i.e. the ability to set any scheme from a limited number of unified elements; block design - the ability to easily replace a failed block. Availability of devices allowing for telecontrol automated installations By minimum quantity communication channels minimal inertia and speedy return to normal for any possible imbalance of the system. Full automation of the operation of auxiliary equipment: regulation of pressure in the return manifold (feeding the heating network), pressure in the deaerator head, water level in the deaerator accumulator tank, etc.

Boiler room protection.

Very important: Use only lightning protected equipment in locking positions.

Protecting the boiler unit in the event of emergency conditions is one of the main tasks of boiler plant automation. Emergency modes arise mainly as a result of incorrect actions of maintenance personnel, mainly when starting the boiler. The protection circuit provides a specified sequence of operations when lighting the boiler and automatically stops the fuel supply when emergency conditions occur.
The protection scheme must solve the following problems:
- control for correct execution pre-launch operations;
— turning on draft devices, filling the boiler with water, etc.;
— monitoring the normal state of parameters (both during startup and during operation of the boiler);
— remote ignition of the igniter from the control panel;
— automatic shutdown of gas supply to the igniters after short-term joint operation of the igniter and the main burner (to check the combustion of the torch of the main burners), if the torches of the igniter and burner have a common control device.
Equipping boiler units with protection when burning any type of fuel is mandatory.
Steam boilers, regardless of pressure and steam production when burning gaseous and liquid fuels, must be equipped with devices that stop the supply of fuel to the burners in the event of:
— increasing or decreasing the pressure of gaseous fuel in front of the burners;
— reducing the pressure of liquid fuel in front of the burners (do not do this for boilers equipped with rotary nozzles);

— decreasing or increasing the water level in the drum;
- reducing the air pressure in front of the burners (for boilers equipped with burners with forced submission air);
— increasing steam pressure (only when boiler rooms are operating without permanent maintenance personnel);


Hot water boilers when burning gaseous and liquid fuels must be equipped with devices that automatically stop the fuel supply to the burners in the event of:
— increasing the water temperature behind the boiler;
— increasing or decreasing the water pressure behind the boiler;
— reducing the air pressure in front of the burners (for boilers equipped with burners with forced air supply);
— increase or decrease of gaseous fuel;
— reducing the pressure of liquid fuel (for boilers equipped with rotary burners, do not perform this);
— reducing vacuum in the furnace;
— reducing water flow through the boiler;
— extinguishing the torch of burners, the shutdown of which is not allowed during boiler operation;
— malfunction of protection circuits, including loss of voltage.
For hot water boilers with a water heating temperature of 115°C and lower, protection for reducing water pressure behind the boiler and reducing water flow through the boiler may not be provided.

Technological alarm in boiler houses.

To warn operating personnel about deviations of the main technological parameters from the norm, a technological warning is provided light and sound alarm. The process alarm circuit of a boiler room is divided, as a rule, into alarm circuits for boiler units and auxiliary equipment of the boiler room. In boiler rooms with permanent maintenance personnel, an alarm system must be provided:
a) stopping the boiler (when the protection is triggered);
b) reasons for protection activation;
c) lowering the temperature and pressure of liquid fuel in the common pipeline to the boilers;
d) reducing the water pressure in the supply line;
e) decreasing or increasing water pressure in the return pipeline of the heating network;
f) increasing or decreasing the level in tanks (deaerator, accumulator hot water supply systems, condensate, feed water, liquid fuel storage, etc.), as well as decreasing the level in wash water tanks;
g) increasing the temperature in liquid additive storage tanks;
h) malfunction of the equipment of installations for supplying boiler houses with liquid fuel (when they are operated without permanent maintenance personnel);
i) increasing the temperature of electric motor bearings at the request of the manufacturer;
j) decreasing the pH value in the treated water (in water treatment schemes with acidification);
k) increasing pressure (deterioration of vacuum) in the deaerator;
m) increasing or decreasing gas pressure.

Control and measuring instruments for boiler rooms.

Instruments for measuring temperature.

IN automated systems Temperature measurement is carried out, as a rule, on the basis of control physical properties bodies functionally related to the temperature of the latter. Temperature control devices based on their operating principle can be divided into the following groups:
1. expansion thermometers to monitor the thermal expansion of a liquid or solids(mercury, kerosene, toluene, etc.);
2. manometric thermometers for temperature control by measuring the pressure of a liquid, steam or gas enclosed in a closed system of constant volume (for example TGP-100);
3. devices with resistance thermometers or thermistors for monitoring the electrical resistance of metal conductors (resistance thermometers) or semiconductor elements (thermistors, TCM, TSP);
4. thermoelectric devices for monitoring the thermoelectromotive force (TEMF) developed by a thermocouple of two various conductors(the value of TEMF depends on the temperature difference between the junction and the free ends of the thermocouple connected to measuring circuit) (TPP, TCA, THC, etc.);
5. Radiation pyrometers for measuring temperature by brightness, color or thermal radiation incandescent body (FEP-4);
6. Radiation pyrometers for measuring temperature by the thermal effect of radiation from an incandescent body (RAPIR).

Secondary temperature measuring instruments.

1. Logometers are designed to measure temperature in combination with thermometers
2. Resistance bridges of standard calibrations 21, 22, 23, 24, 50-M, 100P, etc.
3. Millivoltmeters are designed to measure temperature, complete with
4. Potentiometer with thermocouples of standard calibrations TPP, TXA, TXK, etc.

Instruments for measuring pressure and vacuum (in boiler rooms).

According to the principle of operation, instruments for measuring pressure and vacuum are divided into:
- liquid - pressure (vacuum) is balanced by the height of the liquid column (U-shaped, TJ, TNZh-N, etc.);
- spring - the pressure is balanced by the force of elastic deformation of the sensitive element (membrane, tubular spring, bellows, etc.) (TNMP-52, NMP-52, OBM-1, etc.).

Converters.

1. Differential transformer (MED, DM, DTG-50, DT-200);
2. Current (SAPHIRE, Metran);
3. Electric contact (EKM, VE-16rb, DM-2005, DNT, DGM, etc.).

To measure the vacuum in the boiler furnace, devices of the DIV modification are most often used (Metran22-DIV, Metran100-DIV, Metran150-DIV, Sapphire22-DIV)

Instruments for measuring flow.

To measure the flow of liquids and gases, mainly two types of flow meters are used - variable and constant differential. The operating principle of variable differential flow meters is based on measuring the pressure drop across a resistance introduced into a liquid or gas flow. If you measure the pressure before the resistance and directly behind it, then the pressure difference (difference) will depend on the flow rate, and therefore on the flow rate. Such resistances installed in pipelines are called restriction devices. Normal diaphragms are widely used as restriction devices in flow control systems. A set of diaphragms consists of a disk with a hole, the edge of which makes an angle of 45 degrees with the plane of the disk. The disk is placed between the housings of the annular chambers. Sealing gaskets are installed between the flanges and chambers. Pressure samples before and after the diaphragm are taken from the annular chambers.
Differential pressure gauges (differential pressure gauges) DP-780, DP-778-float are used as measuring instruments and transmitting converters, complete with variable differential converters for flow measurement; DSS-712, DSP-780N-bellows; DM-differential transformer; "SAPHIRE" - current.
Secondary devices for level measurement: VMD, KSD-2 for working with DM; A542 for working with SAPPHIRE and others.

Level measuring instruments. Level alarms.

Designed for signaling and maintaining within specified limits the level of water and liquid electrically conductive media in the tank: ERSU-3, ESU-1M, ESU-2M, ESP-50.
Devices for remote level measurement: UM-2-32 ONBT-21M-selsinny (the device set consists of a DSU-2M sensor and a USP-1M receiver; the sensor is equipped with a metal float); UDU-5M-float.

To determine the water level in the boiler, it is often used, but the piping is not classic, but the other way around, i.e. the positive selection is supplied from the upper point of the boiler (the pulse tube must be filled with water), the minus from the lower point, and the reverse scale of the device is set (on the device itself or secondary equipment). This method measuring the level in the boiler has shown its reliability and stability of operation. It is mandatory to use two such devices on one boiler, one regulator on the second for alarm and blocking.

Instruments for measuring the composition of matter.

Auto stationary gas analyzer MH5106 is designed for measuring and recording oxygen concentration in the exhaust gases of boiler plants. Recently, CO-carbon monoxide analyzers have been included in boiler room automation projects.
Converters type P-215 are intended for use in systems for continuous monitoring and automatic regulation of the pH value of industrial solutions.

Ignition protective devices.

The device is intended for automatic or remote ignition of burners operating on liquid or gaseous fuel, as well as for protecting the boiler unit when the torch goes out (ZZU, FZCh-2).

Direct acting regulators.

The temperature controller is used to automatically maintain the set temperature of liquids and gaseous media. The regulators are equipped with a direct or reverse channel.

Indirect acting regulators.

Automatic control system "Kontur". The Kontur system is intended for use in automatic regulation and control circuits in boiler rooms. Regulating devices of the R-25 (RS-29) type system form, together with the actuators (MEOK, MEO), the “PI” law of regulation.

Automation systems for heating boiler rooms.

The KSU-7 control set is designed for automatic control of single-burner water-heating boilers with a capacity from 0.5 to 3.15 MW, operating on gaseous and liquid fuels.
Technical data:
1. autonomous
2. from the top level of the control hierarchy (from the control center or public control device).
In both control modes, the kit provides the following functions:
1. automatic start and stop of the boiler
2. automatic vacuum stabilization (for boilers with draft), positional control law
3. positional control of the boiler power by turning on the “high” and “small” combustion modes
4. emergency protection, ensuring the boiler stops if emergency situations, turning on the sound signal and remembering the root causes of the accident
5. light signaling about the operation of the kit and the state of the boiler parameters
6. information communication and management communication with the upper level of the management hierarchy.

Features of setting up equipment in boiler rooms.

When setting up a set of KSU-7 controls, special attention must be paid to controlling the flame in the boiler furnace. When installing the sensor, observe the following requirements:
1. orient the sensor to the zone of maximum intensity of flame radiation pulsations
2. there should be no obstacles between the flame and the sensor, the flame must always be in the field of view of the sensor
3. The sensor must be installed with an inclination that prevents the settling of various fractions on its sighting glass
4. the sensor temperature should not exceed 50 C; for which it is necessary to carry out constant blowing through a special fitting in the sensor housing, to provide thermal insulation between the sensor housing and the burner device; FD-1 sensors are recommended to be installed on special tubes
5. use photoresistors FR1-3-150 kOhm as the primary element.

Conclusion.

Recently, devices based on microprocessor technology have become widely used. So, instead of the KSU-7 control set, KSU-EVM is being produced, which leads to an increase in the indicators of perfection of the safety systems used, the operation of equipment and units.