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1 kilogram per second [kg/s] = 3.6 ton (metric) per hour [t/h]

Initial value

Converted value

kilogram per second gram per second gram per minute gram per hour gram per day milligram per minute milligram per hour milligram per day kilogram per minute kilogram per hour kilogram per day exagram per second petagram per second teragram per second gigagram per second megagram per second hectogram in second decagrams per second decigrams per second centigrams per second milligrams per second micrograms per second ton (metric) per second ton (metric) per minute ton (metric) per hour ton (metric) per day ton (short) per hour pound per second pound per minute pound per hour pound per day

More about mass flow

General information

The amount of liquid or gas that passes through certain area over a certain amount of time, can be measured in different ways, for example, by determining mass or volume. In this article we will look at calculation by mass. Mass flow depends on the speed of movement of the medium, the cross-sectional area through which the substance passes, the density of the medium, and the total volume of the substance passing through this area per unit time. If we know the mass and we know either the density or the volume, we can know the other quantity because it can be expressed using the mass and the quantity we know.

Mass flow measurement

There are many ways to measure mass flow and there are many different models flowmeters that measure mass. Below we will look at some of them.

Calorimetric flow meters

Calorimetric flowmeters use temperature differences to measure mass flow. There are two types of such flow meters. In both, the liquid or gas cools the thermal element it flows past, but the difference is what each flow meter measures. The first type of flowmeter measures the amount of energy required to maintain a constant temperature on a thermal element. The higher the mass flow, the more energy it requires. In the second type, the difference in flow temperatures is measured between two points: near the thermal element and at a certain distance downstream. The higher the mass flow, the higher the temperature difference. Calorimetric flow meters are used to measure mass flow in liquids and gases. Flow meters used in liquids or gases that are corrosive are made from materials that resist corrosion, such as special alloys. Moreover, only parts that have direct contact with the substance are made from such material.

Variable differential pressure flowmeters

Variable pressure flow meters create a pressure difference within the pipe through which the fluid flows. One of the most common methods is to partially block the flow of liquid or gas. The greater the measured pressure difference, the higher the mass flow. An example of such a flow meter is diaphragm based flow meter. The diaphragm, that is, a ring installed inside the pipe perpendicular to the flow of liquid, limits the flow of liquid through the pipe. As a result, the pressure of this fluid in the place where the diaphragm is located is different from the pressure in other parts of the pipe. Flowmeters with restriction devices, for example, with nozzles, they work in a similar way, only the narrowing in the nozzles occurs gradually, and the return to normal width occurs instantly, as in the case of a diaphragm. The third type of variable pressure flow meters, called Venturi flow meter in honor of the Italian scientist Venturi, it narrows and expands gradually. A tube of this shape is often called a Venturi tube. You can imagine what it looks like if you place two funnels with narrow parts facing each other. The pressure in the constricted part of the tube is lower than the pressure in the rest of the tube. It should be noted that flowmeters with a diaphragm or restriction device operate more accurately at high pressures, but their readings become inaccurate if the liquid pressure is weak. Their ability to partially retain the flow of water deteriorates with prolonged use, so as they are used, they must be regularly maintained and, if necessary, calibrated. Despite the fact that such flowmeters are easily damaged during operation, especially due to corrosion, they are popular due to their low price.

Rotameter

Rotameters, or variable area flowmeters- these are flow meters that measure mass flow by pressure difference, that is, they are differential pressure flow meters. Their design is usually a vertical tube that connects horizontal inlet and outlet pipes. At the same time inlet pipe is below the output. At the bottom, the vertical tube narrows - that is why such flow meters are called flow meters with a variable cross-section. The difference in cross-sectional diameter creates a pressure difference - just like with other differential pressure flowmeters. A float is placed in a vertical tube. On one side, the float tends upward, since it is acted upon by a lifting force, as well as by liquid moving up the pipe. On the other hand, gravity pulls it down. In the narrow part of the pipe total amount forces acting on the float pushes it up. With height, the sum of these forces gradually decreases until at a certain height it becomes zero. This is the height at which the float will stop moving up and stop. This height depends on constant variables such as the weight of the float, the taper of the tube, and the viscosity and density of the liquid. The height also depends on the variable mass flow rate. Since we know all the constants, or we can easily find them, then, knowing them, we can easily calculate the mass flow if we determine at what height the float stopped. Flow meters that use this mechanism are very accurate, with an error of up to 1%.

Coriolis flow meters

The operation of Coriolis flow meters is based on the measurement of Coriolis forces arising in oscillating tubes through which the medium flows, the flow of which is measured. The most popular design consists of two curved tubes. Sometimes these tubes are straight. They oscillate with a certain amplitude, and when there is no fluid flowing through them, these oscillations are phase-locked, as in Figures 1 and 2 in the illustration. If liquid is passed through these tubes, the amplitude and phase of the oscillations change, and the oscillations of the pipes become asynchronous. The change in phase of the oscillations depends on the mass flow rate, so we can calculate it if we have information about how the oscillations changed when the liquid was released through the pipes.

To better understand what happens to pipes in a Coriolis flow meter, let's imagine a similar situation with a hose. Take the hose attached to the faucet so that it is bent and begin to pump it from side to side. The vibrations will be uniform as long as no water flows through it. As soon as we turn on the water, the vibrations will change and the movement will become serpentine. This movement is caused by the Coriolis effect - the same thing that acts on the pipes in a Coriolis flow meter.

Ultrasonic flow meters

Ultrasonic or acoustic flowmeters transmit ultrasonic signals through liquids. There are two main types of ultrasonic flowmeters: Doppler and time-pulse flowmeters. IN Doppler flow meters The ultrasonic signal sent by the sensor through the liquid is reflected and received by the transmitter. The difference in frequency of the sent and received signals determines the mass flow. The higher this difference, the higher the mass flow.

Time-pulse flow meters compare the time it takes for a sound wave to reach a receiver downstream with the time taken upstream. The difference between these two quantities is determined by the mass flow rate - the larger it is, the higher the mass flow rate.

These meters do not require the devices that emit the ultrasonic wave, the reflectors (if used), and the receiving sensors to be in contact with the liquid, so they are convenient for use with liquids that are corrosive. On the other hand, the liquid must pass ultrasonic waves, otherwise the ultrasonic flow meter will not work in it.

Ultrasonic flowmeters are widely used to measure the mass flow of open streams, such as in rivers and canals. These meters can also measure mass flow in sewers and pipes. The information obtained from the measurements is used to determine the ecological state of the water stream, in agriculture and fish farming, in the treatment of liquid waste, and in many other industries.

Converting mass flow to volumetric flow

If the density of the liquid is known, then the mass flow rate can be easily converted to volumetric flow, and vice versa. Mass is found by multiplying density by volume, and mass flow can be found by multiplying volume flow by density. It is worth remembering that volume and volumetric flow change with changes in temperature and pressure.

Application

Mass flow is used in many industries and in everyday life. One application is to measure water flow in private homes. As we discussed earlier, mass flow is also used to measure open flows in rivers and canals. Coriolis and variable area flowmeters are often used in waste treatment, mining, paper and pulp production, power generation, and petrochemical extraction. Some types of flow meters, such as transition flow meters, are used in complex systems assessments of various profiles. In addition, information about mass flow is used in aerodynamics. There are four main forces acting on an airplane: lift (B), directed upward; thrust (A), parallel to the direction of movement; weight (C) directed towards the Earth; and drag (D), directed opposite to the movement.

Air mass flow affects the movement of an airplane in several ways, and we'll look at two of them below: the first is the overall flow of air past the airplane, which helps the airplane stay in the air, and the second is the flow of air through the turbines, which helps the airplane move forward. Let's consider the first case first.

Let's consider what forces influence the plane during flight. It is not easy to explain the action of some of them within the framework of this article, so we will talk about them in general, using a simplified model, without explaining small details. The force that pushes the plane upward and is labeled B in the illustration is - lift.

The force that, due to the gravity of our planet, pulls the plane towards the Earth is its weight, indicated in the figure by the letter C. In order for the plane to remain in the air, the lift force must overcome the weight of the plane. Drag- the third force that acts on the plane in the direction opposite to the movement. That is, drag resists forward movement. This force can be compared to the force of friction, which slows down the movement of a body on a solid surface. Drag is indicated in our illustration by the letter D. The fourth force that acts on the airplane is traction. It occurs as the engines operate and pushes the plane forward, that is, it is directed opposite to the drag. In the illustration it is indicated by the letter A.

The mass flow of air that moves relative to the aircraft affects all of these forces except weight. If we try to derive a formula for calculating mass flow using force, we will notice that if all other variables are constant, then the force is directly proportional to the square of the speed. This means that if you double the speed, the force will quadruple, and if you triple the speed, the force will increase nine times, and so on. This relationship is widely used in aerodynamics, since this knowledge allows us to increase or decrease speed by changing force, and vice versa. For example, to increase lift we can increase speed. You can also increase the speed of the air that is forced through the engines to increase thrust. Instead of speed, you can change the mass flow.

Don't forget that lift is affected not only by speed and mass flow, but also by other variables. For example, decreasing air density reduces lift. The higher the plane rises, the lower the air density, therefore, in order to use fuel most economically, the route is calculated so that the altitude does not exceed the norm, that is, so that the air density is optimal for movement.

Now consider an example where mass flow is used by turbines through which air passes to create thrust. In order for the aircraft to overcome drag and weight and be able to not only stay in the air for required height, but also to move forward at a certain speed, the thrust must be high enough. Airplane engines create thrust by passing a large flow of air through turbines and pushing it out with great force, but over a short distance. The air moves away from the airplane in the opposite direction to its motion, and the airplane, according to Newton's third law, moves in the opposite direction to the air's motion. By increasing mass flow, we increase thrust.

To increase thrust, instead of increasing mass flow, you can also increase the speed at which air exits the turbines. In airplanes, this consumes more fuel than increasing mass flow, so this method is not used.

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Saturated or superheated steam for the technological needs of enterprises. Boilers are available in three types:

E(KE) with productivity 2.5; 4; 6.5; 10 and 25 t/h with layer combustion devices;

E(DE) with productivity 4; 6.5; 10; 16 and 25 t/h with gas-oil burners;

DKVR with productivity 2.5; 4; 6.5 and 10 t/h with gas-oil furnaces.

Steam boilers type E(KE) with layer combustion devices.

Steam boilers of type E (KE) have the following versions: E-2.5-1.4R (KE-2.5-14S); E-4-1.4R (KE-4-14S); E-6.5-1.4R (KE-6.5-14S); E-10-1.4R (KE-10-14S).

The main elements of type E(KE) boilers (Fig. 73) are upper and lower drums with an internal diameter of 1000 mm, left and right side screens and a convective beam made of pipes

0 51 X 2.5 mm. In addition, the boiler is equipped with equipment, the list of which is given in table. 46 (for all types of boilers, blower fan VDN-9).

Boilers of type E (KE) (Table 47) are supplied to consumers in assembled blocks, with a frame frame, without lining or cladding.

Steam boiler type E-25-1.4R (KE-25S) with a layer combustion device. The boiler (Fig. 74) consists of two drums (upper and lower), having an internal diameter of 1000 mm and a wall thickness of 13 mm.

The combustion chamber of the boiler, 2710 mm wide, is completely shielded by pipes 0 51 X 2.5 mm (screening degree 0.8).

To burn hard and brown coals, a mechanical firebox TCZM-2.7/5.6 is placed under the boiler, which consists of a flake chain return grate and two pneumo-mechanical feeders with a plate feeder ZP-600. Active area of ​​the combustion mirror

Rice. 73. Steam boiler E-2.5-1.4R: / - grate; 2 - side screen; 3 - upper drum; “/ - feed water supply pipeline; 5 - boiling pipes; 6 - lower drum; 7 - service area; 8 - lining; 9 - firebox

Rice. 74. Steam boiler E-25-1.4R:

/ - chain grille; 2 - fuel feeder; 3 - side screen; 4 - rear screen; 5 - upper drum; 6 - supply pipe feed water; 7 - lower drum; 8 - air heater; 9 - bypass pipes; 10 - service area

The tail surfaces consist of a single-pass air heater VP-228 with a heating surface of 228 m2, which provides air heating to approximately 145 °C and a cast iron economizer EP1-646 with a heating surface of 646 m installed after it along the gas flow.

The boiler kit includes a VDN-12.5 fan with a 55 kW (1000 min-1) electric motor, a DN-15 smoke exhauster with a 75 kW (1000 min-1) electric motor, and a BC-2 X 6 X 7 ash collector for cleaning flue gases.

Convective superheater Volume, m3 water steam

Efficiency when burning coal, %

Coal consumption, kg/h

TOC o "1-5" h z stone 3080

Brown 5492

Dimensions(with platforms 12 640 X 5628 X 7660 and stairs), mm

Weight, kg 37,372

* Boilers of type E-25R are also available with an absolute steam pressure of 2.4 MPa (24 kgf/cmg). In boilers with superheaters. the temperature of the superheated steam is 250°C. In necessary and technically justified cases, it is allowed to manufacture boilers with a steam temperature of 350 °C.

Steam gas-oil boilers type E(DE). Gas-oil boilers of type E(DE) (Table 48), depending on the steam output, are produced in the following versions: E-4-1.4GM (DE-4.0-14GM);

E-6.5-1.4GM (DE-6.5-14GM); E-10-1.4GM (DE-10-14GM); E-16-1.4GM (DE-16-14GM); E-25-1.4GM (DE-25-14GM).

Main components The listed boilers (Fig. 75) are the upper and lower drums, the convective beam, the front, side and rear screens that form the combustion chamber.

Boilers with steam capacity 4; 6.5 and 10 t/h are made with a single-stage evaporation scheme. In boilers with a capacity of 16 and 25 t/h, two-stage evaporation is used.

The boilers are supplied in two blocks, including upper and lower drums with internal drum devices, a pipe system of screens and a convection beam (if necessary, a superheater), a support frame and a piping frame.

V-v

Type E (DE) boilers are equipped with additional equipment (Table 49).

Steam gas and oil boiler type E-25-2.4GM. Designed to produce superheated steam with a working pressure of 2.4 MPa (24 kgf/cm2) and a temperature of 380°C, used to drive steam turbines and for the technological needs of the enterprise.

The boiler E-25-2.4GM (DE-25-24-380GM) is a two-drum vertical water-tube unit equipped with a fully shielded firebox.

The combustion chamber screens are made of pipes 0 51 X 2.5 mm. The boiler is equipped with a cast iron economizer made from VTI pipes type EP-1 from to
heating surface 808 m2, VGDN-19 smoke exhauster with 4A31556UZ electric motor and VDN-11.2 fan with 4A200M6 electric motor.

A GMP-16 burner with a two-stage fuel combustion chamber was used as a burner device. The burner device consists of a GM-7 gas-oil burner and a lined fire brick combustion chamber with an annular air guide device in its middle part.

Steam boilers DKVR-2.5; DKVr-4; DKVR-6.5 and DKVR-10 with gas-oil furnaces. Designed to produce saturated or slightly superheated steam used for the technological needs of enterprises, heating, ventilation and hot water supply systems.

Currently, serial production of DKVR type boilers has been discontinued, however, a significant number of these boilers are used at canning enterprises (Tables 50, 51).

Exercise

1. Characteristics of the boiler unit

1.1 Technical characteristics of the boiler KE-25-14S

2. Calculation of fuel by air

2.1 Determination of the amount of combustion products

2.2 Determination of enthalpy of combustion products

3. Verification thermal calculation

3.1 Preliminary heat balance

3.2 Calculation of heat transfer in the furnace

3.3 Calculation of heat transfer in a convective surface

3.4 Economizer calculation

4. Final heat balance

Bibliography

Exercise

Complete the design of a stationary steam boiler in accordance with the following data:

boiler type KE-25-14S

full performance saturated steam, D, kg/s 6,94

working pressure (excessive), R, MPa 1,5

feed water temperature:

to the economizer, t pv1, ºС 90

behind the economizer, t pv2, ºС 170

temperature of air entering the furnace:

to the air heater, t v1, ºС 25

behind the air heater, tВ2, ºС 180

fuel KU-DO

fuel composition: C g = 76.9%

N g = 5.4% g = 0.6%

O g = 16.0% g = 1.1%

Fuel ash content A c = 23%

fuel moisture W p = 7.5%

excess air coefficient α = 1.28.

stationary thermal steam boiler

1. Characteristics of the boiler unit

Steam boiler KE-25-14S, with natural circulation with layered mechanical fireboxes designed to generate saturated or superheated steam used for the technological needs of industrial enterprises, in heating, ventilation and hot water supply systems.

The combustion chamber of KE series boilers is formed by side screens, front and back walls. Combustion chamber of KE boilers with steam output from 2.5 to 25 t/h divided brick wall for a firebox with a depth of 1605÷2105 mm and an afterburning chamber with a depth of 360÷745 mm, which allows you to increase the efficiency of the boiler by reducing mechanical underburning. The entrance of gases from the furnace into the afterburning chamber and the exit of gases from the boiler are asymmetrical. It is tilted under the afterburning chamber in such a way that the bulk of the pieces of fuel falling into the chamber roll onto the grate.

The KE-25-14S boiler uses a single-stage evaporation scheme. The water circulates as follows: feed water from the economizer is supplied to the upper drum under the water level through a perforated pipe. Water is drained into the lower drum through the rear heated pipes of the boiler bundle. The front part of the beam (from the front of the boiler) is lifting. From the lower drum, water flows through overflow pipes into the chambers of the left and right screens. The screens are also fed from the upper drum via lower risers located at the front of the boiler.

The boiler block KE-25-14S is supported by the chambers of the side screens on longitudinal channels. The chambers are welded to the channels along their entire length. In the area of ​​the convection beam, the boiler block rests on the rear and front transverse beams. The transverse beams are attached to the longitudinal channels. The front beam is fixed, the rear beam is movable.

The binding frame of the KE-25-14S boiler is installed on corners welded along the chambers of the side screens along the entire length.

To make it possible to move the elements of the KE-25-14S boiler blocks in a given direction, some of the supports are made movable. They have oval holes for bolts that secure them to the frame.

KE boilers with grate and economizer are delivered to the customer in one transportable unit. They are equipped with an entrainment return system and a sharp blast. The entrainment, settling in four ash pans of the boiler, is returned to the furnace using ejectors and introduced into the combustion chamber at a height of 400 mm from the grate. The mixing pipes for entrainment return are made straight, without turns, which ensures reliable operation of the systems. Access to the entrainment return ejectors for inspection and repair is possible through hatches located on the side walls. In places where hatches are installed, the pipes of the outermost row of the bundle are inserted not into the collector, but into the lower drum.

The KE-25-14S steam boiler is equipped with a stationary device for cleaning heating surfaces according to the plant design.

The KE-25-14S steam boiler is equipped with a firebox of the ZP-RPK type with pneumomechanical throwers and a grate with rotary grates.

Behind boiler units in case of combustion of hard and brown coals with reduced humidity W< 8 устанавливаются водяные экономайзеры.

Boiler platforms of the KE type are located in places necessary for servicing boiler fittings. Main boiler platforms: side platform for servicing water indicating devices; side platform for servicing safety valves and shut-off valves on the boiler drum; a platform on the rear wall of the boiler for servicing the purge line from the upper drum and for access to the upper drum when repairing the boiler.

There are stairs leading to the side landings, and a descent (short staircase) from the upper side landing to the back landing.

The KE-25-14 C boiler is equipped with two safety valves, one of which is control. For boilers with superheaters, the control safety valve is installed on the outlet manifold of the superheater. A pressure gauge is installed on the upper drum of each boiler; If there is a superheater, the pressure gauge is also installed on the outlet manifold of the superheater.

The following fittings are installed on the upper drum: the main steam valve or valve (for boilers without a superheater), valves for sampling steam, sampling steam for auxiliary needs. A shut-off valve with a nominal bore of 50 is installed on the elbow for draining water. mm.

In the KE-25-14S boiler, periodic and continuous blowdowns are carried out through the purge pipe. Shut-off valves are installed on the periodic purge lines from all lower chambers of the screens. The blower steam line is equipped with drain valves to remove condensate when the line is heated and shut-off valves for supplying steam to the blower. Instead of steam blowing, a gas pulse or shock wave generator (SHW) can be installed.

On the supply pipelines in front of the economizer, they are installed check valves and shut-off valves; A power control valve is installed in front of the check valve, which is connected to the boiler automation actuator.

The KE-25-14S steam boiler provides stable operation in the range from 25 to 100% of the nominal steam output. Tests and operating experience large number boilers of the KE type have confirmed their reliable operation at a lower pressure than the nominal pressure. With decreasing operating pressure Boiler efficiency does not decrease, which is confirmed by comparative thermal calculations of boilers at nominal and reduced pressure. In boiler houses intended for the production of saturated steam, boilers of the KE type are reduced to 0.7 MPa pressure provide the same performance as at pressure 1.4 MPa.

For KE type boilers, the throughput of the safety valves corresponds to the rated steam output at an absolute pressure of 1.0 MPa.

When operating at reduced pressure, safety valves on the boiler and additional safety valves installed on the equipment must be adjusted to the actual operating pressure.

With a decrease in pressure in boilers to 0.7 MPa The equipment of boilers with economizers does not change, since in this case the underheating of water in feed economizers to the steam saturation temperature in the boiler is 20°C, which meets the requirements of the Gosgortekhnadzor rules.

1.1 Technical characteristics of the boiler KE-25-14S

Steam capacity D = 25 t/h.

Pressure R = 24 kgf/cm 2 .

Steam temperature t= (194÷225) ºС.

Radiation (beam-receiving) heating surface N l = 92.1 m 2 .

Convective heating surface N k = 418 m 2 .

Type of combustion device TCHZ-2700/5600.

Combustion mirror area 13.4 m 2 .

Overall dimensions of the boiler (with platforms and stairs):

length 13.6 m;

width 6.0 m;

height 6.0 m.

Boiler weight 39212 kg.

2. Calculation of fuel by air

2.1 Determination of the amount of combustion products

The calculation of the amount of combustion products is based on stoichiometric ratios and is performed with the aim of determining the amount of gases formed during the combustion of fuel of a given composition at a given excess air ratio. All calculations of the volume of air and combustion products are carried out on 1 kg fuel.

Since the task indicates the ash content of the dry mass of the fuel, we will determine the ash content of the working mass of the fuel.

A r = A s (100 - W r) / 100,

A p = 2.3∙ (100 - 7.5) /100 = 21.3%.

Conversion factor of combustible mass into working mass

(100 - W р - А р) /100 = (100 - 7.5 - 21.3) /100 = 0.71.

Operating mass of fuel components

C p = 76.9 ∙ 0.71 = 54.6%, H p = 5.4 ∙ 0.71 = 3.9%, p = 0.6 ∙ 0.71 = 0.5%,

О р = 16.0 ∙ 0.71 = 11.4%, р = 1.1 ∙ 0.71 = 0.8%.

Examination:

р + Н р + S р + О р + N р + А р + W р = 100%,

6 + 3,9 + 0,5 + 11,4 + 0,8 + 21,3 + 7,5 = 100%.

Theoretically required quantity dry air

o = 0.089 (C p + 0.375S p) + 0.267H p - 0.033O p; o = 0.089∙ (54.6 + 0.375 ∙ 0.5) + 0.267 ∙ 3.9 - 0.033 ∙ 11.4 = 5.54 m 3 /kg.

Volume of triatomic gases

V = 0.01866 (C p + 0.375S p); = 0.01866∙ (54.6 + 0.375 ∙ 0.5) = 1.02 m 3 /kg.

Theoretical nitrogen volume

0.79V o + 0.008N p; V = 0.79 ∙ 5.54 + 0.008 ∙ 0.8 = 4.38 m 3 /kg.

Theoretical volume of water vapor

0.112Н р + 0.0124W р + 0.016V о; = 0.112 ∙ 3.9 + 0.0124 ∙ 7.5 + 0.016 ∙ 5.54 = 0.61 m 3 /kg.

Theoretical amount of humid air

o vl = V + 0.016V o; (2.8), V = 0.61 + 0.016 ∙ 5.54 = 0.70 m 3 /kg.

Excessive air volume

and = (α - 1) V o; u = 0.28 ∙ 5.54 = 1.55 m 3 /kg.

Total volume of combustion products

r = V+ V + V+ V and; g = 1.02 + 4.38 + 0.61 + 1.55 = 7.56 m 3 /kg.

Volume fraction of triatomic gases

V/V g; = 1.02/7.56 = 0.135.

Volume fraction of water vapor

V/V g; r = 0.70/7.56 = 0.093.

Total fraction of water vapor and triatomic gases

n = r+ r, n = 0.093 + 0.135 = 0.228.

The pressure in the boiler furnace is taken equal to P t = 0.1 MPa.

Partial pressure of triatomic gases

Р= 0.135 ∙ 0.1 = 0.014 MPa.

Partial pressure of water vapor

P = 0.093 ∙ 0.1 = 0.009 MPa.

Total partial pressure

P p = P + P; R p = 0.014 + 0.009 = 0.023 MPa.

2.2 Determination of enthalpy of combustion products

Flue gases formed as a result of fuel combustion act as a coolant in the working process of a steam boiler. The amount of heat given off by gases can be conveniently calculated from the change in enthalpy of the flue gases.

The enthalpy of flue gases at any temperature is the amount of heat spent on heating the gases obtained from the combustion of one kilogram of fuel from 0º to this temperature at constant gas pressure in the furnace.

The enthalpy of combustion products is determined in the temperature range 0…2200ºС with an interval of 100ºС. We carry out the calculations in tabular form (Table 2.1).

The initial data for the calculation are the volumes of gases that make up the combustion products, their volumetric isobaric heat capacities, excess air coefficient and gas temperature.

We take the average isobaric heat capacities of gases from reference tables.

The theoretical amount of gases is determined by the formula

I = ΣV c t= VC+ VC + VC) t.

The theoretical enthalpy of moist air is determined by the formula

V o C cc t.

r = I + (α - 1) I.

Table 2.1 Calculation of enthalpy of combustion products

The theoretical enthalpy of moist air is determined by the formula

I = V o C inc t.

The enthalpy of gases is determined by the formula

r = I + (α - 1) I.

Based on the calculation results (Table 2.1), we construct a diagram of the dependence of the enthalpy of gases I 1 from their temperature t(Fig. 2.1).

Fig. 2.1 - Diagram of the dependence of the enthalpy of gases on their temperature

3. Verification thermal calculation

3.1 Preliminary heat balance

When a steam boiler operates, all the heat entering it is spent on generating useful heat contained in the steam and covering various heat losses. The total amount of heat entering the boiler is called available heat. There must be equality (balance) between the heat entering the boiler and leaving it. The heat leaving the boiler is the sum of useful heat and heat losses associated with the technological process of generating steam of specified parameters.

The heat balance of the boiler is compiled in relation to one kilogram of fuel under steady-state (stationary) boiler operation.

The lower calorific value of the working mass of fuel is determined using the Mendeleev formula:

n r = 339C r + 1030H r - 109 (O r - S r) - 25W r, n r = 339 ∙ 54.6 + 1030 ∙ 3.9 - 109 ∙ (11.4 - 0.5) - 25 ∙ 7.5 = 21151 kJ/kg.

Coefficient useful action boiler (accepted according to the prototype)

Heat loss:

from chemical incomplete combustion (p.15)

3 = (0.5÷1.5) = 0.5%;

from mechanical underburning (Table 4.4) 4 = 0.5%;

into the environment (Fig. 4.2) 5 = 0.5%;

with flue gases

2 = 100 - (η" + q 3 + q 4 + q 5), 2 = 100 - (92 + 0.5 + 0.5 + 0.5) = 6.5%.

Average isobaric volumetric heat capacities of moist air

cold, at a temperature t v1 (Table 1.4.5)

With b1 = 1.32 kJ/kg;

heated, at a temperature t v2 (Table 1.4.5)

With b1 = 1.33 kJ/kg.

The amount of heat introduced into the furnace with air:

cold

xv = 1.016αV o With in1 t b1, xb = 1.016 ∙ 1.28 ∙ 5.54 ∙ 1.32 ∙ 25 = 238 kJ/kg;

warmed up

gv = 1.016αV o With v2 t v2, gv = 1.016 ∙ 1.28 ∙ 5.54 ∙ 1.33 ∙ 180 = 1725 kJ/kg.

The amount of heat transferred in the air heater

vn = I gv - I hv, vn = 1725 - 238 = 1487 kJ/kg.

We assume the temperature of the fuel entering the furnace is equal to

t tl = 30°C.

Heat capacity of dry mass of fuel (Table 4.1)

s s tl = 0.972 kJ/ (kg deg).

Heat capacity of the working fuel mass

c p tl = c c tl (100 - W p) /100 + cW p /100,

Where With- heat capacity of water, With= 4,19 kJ/ (kg deg),

s р tl = 0.972 · (100 - 7.5) /100 + 4.19 · 7.5/100 = 1.21 kJ/ (kg deg).

Heat introduced into the furnace with fuel

tl = c p tl t tl,

i tl = 1.21 30 = 36 kJ/kg.

Available heat of fuel

Q + Q int + i tl, = 21151 + 1487 + 36 = 22674 kJ/kg.

Flue gas enthalpy

"ух = q 2 Q р р / (100 - q 4) + I хв," ух = 6.5 ∙ 22674/ (100 - 4.5) + 238 = 1719 kJ/kg.

Flue gas temperature (Table 1)

t"uh = 164°C.

We accept the degree of dryness of the resulting steam (p. 17)

X = (0,95…0,98) = 0,95.

Enthalpy of dry saturated steam (according to water vapor tables) at a given pressure

i" = 2792 kJ/kg.

Latent heat of vaporization

r = 1948 kJ/kg.

Enthalpy of wet steam

i x = i" - (1 - x) r,

i x= 2792 - (1 - 0.95) 1948 = 2695 kJ/ kg.

Enthalpy of feedwater before the economizer (at t c2)

i pv = 377 kJ/kg.

Secondary fuel consumption

B p = = 0,77 kg/s.

3.2 Calculation of heat transfer in the furnace

The purpose of the verification calculation of heat transfer in the firebox is to determine the temperature of the gases behind the firebox and the amount of heat transferred by the gases to the heating surface of the firebox.

This heat can only be found with known geometric dimensions of the firebox: the size of the radiation-receiving surface, N l, full surface walls limiting the combustion volume, F st, the volume of the combustion chamber, V T.

Fig.3.1 - Sketch of the KE-25-14S steam boiler

The beam-receiving surface of the firebox is found as the sum of the beam-receiving surfaces of the screens, i.e.

Where N le - surface of the left side screen,

N pe - surface of the right side screen;

N z - surface of the rear screen;

N le = N pe = L t l bae X bae;

N ze = V ze l ze X bae;

t - length of the firebox;

l bе is the length of the side screen tubes;

IN ze - width of the rear screen;

X bе - angular coefficient of the side screen;

l ze is the length of the rear screen tubes;

X ze is the angular coefficient of the rear screen.

Due to the difficulty of determining the lengths of the tubes, we take the size of the radiation-receiving heating surface from the technical characteristics of the boiler:

N l = 92.1 m 2 .

Full surface of the furnace walls, F st, is calculated from the dimensions of the surfaces limiting the volume of the combustion chamber. We reduce surfaces of complex configuration to an equal-sized simple geometric figure.

Furnace wall surface area:

boiler front

fr = 2.75 ∙ 4.93 = 13.6 m 2 ;

back wall of the firebox

zs = 2.75 ∙ 4.93 = 13.6 m 2 ;

firebox side wall

bs = 4.80 ∙ 4.93 = 23.7 m 2 ;

under the firebox

under = 2.75 ∙ 4.80 = 13.2 m 2 ;

firebox ceiling

sweat = 2.75 ∙ 4.80 = 13.2 m 2 .

The full surface of the walls delimiting the combustion volume

st = F fr + F zs + 2F bs + F under + F sweat, st = 13.6 + 13.6 + 2 ∙ 23.7 + 13.2 + 13.2 = 101.0 m 2 .

Combustion volume:

t = 2.75 ∙ 4.80 ∙ 4.93 = 65.1 m 3 .

Firebox screening degree

Ψ = N l / F st,

Ψ = 92.1/101.0 = 0.91.

Heat retention coefficient

φ = 1 - q 5 /100,

φ = 1 - 0.5/100 = 1.00.

Effective thickness of the radiating layer

3.6V t /F st, = 3.6 65.1/101.0 = 2.32 m.

Adiabatic (theoretical) enthalpy of combustion products

a = Q (100 - q 3 - q 4) / (100 - q 4) + I gv - Q vn, a = 22674 (100 - 0.5 - 0.5) / (100 - 0.5) + 1725 - 1487 = 22798 kJ/kg.

Adiabatic (theoretical) temperature of gases (Table 1)

T a = 1835°C = 2108 TO.

We take the temperature of the gases at the outlet of the furnace

T" t = 800°C = 1073 TO.

Enthalpy of gases at the exit from the furnace (Table 1) at this temperature" t = 9097 kJ/kg.

Average total heat capacity of combustion products

(V g C av) = (I a - I "t) / ( t a- t" T),

(V g C avg) = (22798 - 9097) / (1835 - 800) = 13.24 kJ/ (kg deg).

Conditional coefficient (Table 5.1) of heating surface contamination during layer combustion of fuel

Thermal stress of the combustion volume

v = BQ/V t, v = 0.77 22674/65.1 = 268 kW/m 3 .

Thermal efficiency coefficient

Ψ e = 0.91 · 0.60 = 0.55.

,

∙0,228 = 5,39 (m MPa) - 1 .

Coefficient of attenuation of rays by soot particles

s = 0.3 (2 - α) (1.6T t /1000 - 0.5) C r /H r, s = 0.3 (2 - 1.28) (1.6 1073/1000 - 0.5) 54.6/3.9 = 3.68 ( m MPa) - 1 .

Part of the fuel ash carried away from the furnace into the convective flues (Table 5.2)

Flue gas mass

g = 1 - A p /100 + 1.306αV o, g = 1 - 21.3/100 + 1.306 1.28 5.54 = 10.0 kg/kg.

The coefficient of attenuation of rays by suspended particles of fly ash (Fig. 5.3) at accepted temperature t T

k zł = 7.5 ( m ata) - 1 .

Coefficient of attenuation of rays by particles of burning coke (p.29)

k k = 0.5 ( m ata) - 1 .

Concentration of ash particles in the gas stream

μ PLN = 0.01 A r a u n /G g, μ PLN = 0.01 · 21.3 · 0.1/10.0 = 0.002.

Coefficient of attenuation of rays by the combustion medium

k t = 5.39 + 7.5 0.002 + 0.5 = 5.91 ( m ata) - 1 .

Effective flame blackness

and f = 1 - e -k tPtS,

a f = 1 - 2.7 -5.91·0.1·2.32 = 0.74.

The ratio of the combustion mirror to the total surface of the furnace walls during layer combustion

ρ = F under /F st,

ρ = 13.2/101.0 = 0.13.

The degree of blackness of the furnace during layer combustion of fuel

a t = ,

a t = = 0,86.

The value of the relative position of the maximum temperature for layer furnaces when burning fuel in a thin layer (furnaces with pneumomechanical throwers) is taken (p. 30) equal to:

Parameter characterizing the temperature distribution along the height of the firebox (f.5.25)

M = 0.59 - 0.5X t, M = 0.59 - 0.5 0.1 = 0.54.

Estimated temperature of gases behind the furnace

T t = ,

T t = = 1090 TO= 817°C.

The discrepancy with the previously accepted value is

∆t t = t T - t" T,

∆t t = 817 - 800 = 17°C< ± 100°C.

Enthalpy of gases behind the furnace t = 9259 kJ/kg.

The amount of heat transferred in the firebox

t = φВ (I a - I t), t = 1.00 0.77 (22798 - 9259) = 10425 kW.

Direct return coefficient

μ = (1 - I t /I a) 100,

μ = (1 - 9259/22798) 100 = 59.4%.

Actual thermal stress of the combustion volume

v = Q t /V t, q v = 10425/65.1 = 160 kW/m 3 .

3.3 Calculation of heat transfer in a convective surface

Thermal calculation of the convective surface serves to determine the amount of heat transferred and comes down to solving a system of two equations - the equation heat balance and heat transfer equations.

The calculation is performed for 1 kg burning fuel under normal conditions.

From previous calculations we have:

gas temperature in front of the gas duct in question

t 1 = t t = 817°C;

enthalpy of gases in front of the flue 1 = I t = 9259 kJ/kg;

heat retention coefficient

second fuel consumption

B p = 0.77 kg/s.

We first accept two values ​​for the temperature of combustion products after the flue:

t" 2 = 220ºC,

t"" 2 = 240ºC.

We carry out further calculations for two accepted temperatures.

Enthalpy of combustion products after the convective beam: "2 = 2320 kJ/kg,"" 2 = 2540 kJ/kg.

The amount of heat given off by gases in the beam:

1 = φВ р (I t - I 1); " 1 = 1.00 ∙ 0.77 (9259 - 2320) = 5343 kJ/kg,"" 1 = 1.00 · 0.77∙ (9259 - 2540) = 5174 kJ/kg.

Outer diameter of convective bundle pipes (according to drawing)

d n = 51 mm.

The number of rows along the flow of combustion products (according to the drawing) 1 = 35.

Transverse pipe pitch (according to drawing) 1 = 90 mm.

Longitudinal pitch of pipes (according to drawing) 2 = 110 mm.

Pipe washing coefficient (Table 6.2)

Relative transverse σ 1 and longitudinal σ 2 pipe pitches:

σ 1 = 90/51 = 1.8;

σ 2 = 110/51 = 2.2.

Clear cross-sectional area for the passage of gases during cross-flushing of pipes

f = ab- z 1 l d n,

Where A And b- dimensions of the flue in the clear, m;

l- length of the projection of the pipe onto the plane of the section under consideration, m;

w = 2.5 ∙ 2.0 - 35 ∙ 2.0 ∙ 0.051 = 1.43 m 2 .

Effective thickness of the radiating layer of gases

S eff = 0.9d n, eff = 0.9 0.051 = 0,177 m.

Boiling point of water at operating pressure (according to tables of saturated water vapor)

t" s = 198°C.

Average gas flow temperature

av1 = 0.5 ( t 1 + t);

t" av1 = 0.5 (817 + 220) = 519ºC,

t"" av1 = 0.5· (817 + 240) = 529ºC.

Average gas consumption

V"" cp1 = 0.77 7.56 (529 + 273) /273 = 17.10 m 3 /With.

Average gas speed

ω g1 = V cp1 /F w,

ω" g1 = 16.89/1.43 = 11.8 m/s,

ω"" g1 = 17.10/1.43 = 12.0 m/s.

Heating surface contamination coefficient (p.43)

ε = 0.0043 m 2 hail/Tue

Average temperature of the contaminated wall (p.42)

z = t" s + (60÷80), t h = (258÷278) = 270°C.

Correction factors for determining the heat transfer coefficient by convection (Fig. 6.2):

by the number of rows

into relative steps

to change physical characteristics

Viscosity of combustion products (Table 6.1)

ν" = 76·10 -6 m 2 /With,

ν"" = 78·10 -6 m 2 /With.

Thermal conductivity coefficient of combustion products (Table 6.1)

λ" = 6.72·10 -2 W/ (m°C),

λ"" = 6.81·10 -2 W/ (m°C).

Prandtl criterion for combustion products (f.6.7)

Pr" = 0.62, Pr"" = 0.62.

Heat transfer coefficient by convection (Table 6.1)

α k1 = 0.233С z C f λР (ωd n /ν) 0.65 /d n,

α" k1 = 0.233 1 1.05 6.72 10 -2 0.62 0.33 (11.8 0.051/76 10 -6) 0.65 /0.051.α" k1 = 94.18 W/ (m 2 · TO);

α"" k1 = 0.233 · 1 · 1.05 · 6.81·10 -2 · 0.62 0.33 · (12.0 · 0.051/78·10 -6) 0.65 /0.051,α"" k1 = 94.87 W/ (m 2 · TO).

Coefficient of attenuation of rays by triatomic gases

,

·0.228 = 23.30 ( m MPa) -

1, ·0.228 = 23.18 ( m MPa) -

1, Total partial pressure of triatomic gases (previously defined)

R p = 0.023 MPa.

Beam attenuation coefficient in a volume filled with ash at temperature t cf (Fig. 5.3)

K"" zl = 9.0.

Concentration of ash particles in the gas stream (previously determined)

μ zl = 0.002.

Blackness degree of dust-laden gas flow

a = 1 - e-kgkzlRp μ zlSef,

a" = 1 - e-23.30 9.0 0.002 0.023 0.177 = 0.002,a"" = 1 - e-23.18 9.0 0.002 0.023 0.177 = 0.002.

Radiation heat transfer coefficient when burning coal

a l = 5.67·10 -8 (a st + 1) aT 3 /2,

Where A st - degree of blackness of the wall, accepted (p.42)

a st = 0.82;
kJ/kg ;"" k = 62.46 · 418 · 214/1000 = 5587 kJ/kg.

According to the accepted two temperature values

t" 1 = 220ºC;

t"" 1 = 240ºC

and the obtained values

" b1 = 5343 kJ/kg;"" b1 = 5174 kJ/kg;" k1 = 4649 kJ/kg;"" k1 = 5587 kJ/kg

We perform graphical interpolation to determine the temperature of combustion products after the convective heating surface. For graphical interpolation, we build a graph (Fig. 3.2) of the dependence Q = f (t).

Fig.3.2 - Graph of dependence Q = f (t)

The point of intersection of the lines will indicate the temperature t p of gases escaping after the convective surface:

t k = 232ºС.

The amount of heat absorbed by the heating surface k1 = 5210 kW.

Enthalpy of gases at this temperature

I k1 = 2452 kJ/kg.

3.4 Economizer calculation

Enthalpy of feedwater at the economizer inlet

i xv = 377 kJ/kg.

Enthalpy of feedwater leaving the economizer

i gv = 719 kJ/kg.

Heat retention coefficient (found earlier)

The amount of heat given off by the flue gases in the economizer

ek = D ( i gv - i xv);

Q eq = 6.94∙ (719 - 377) = 2373 kJ.

Enthalpy of flue gases behind the economizer х = I к - Q eq /В р, ух = 2452 - 2373/0.77 = 103 kJ/kg.

Flue gas temperature behind the economizer

tх = 10ºС.

4. Final heat balance

After performing a thermal calculation, the final heat balance is established, the purpose of which is to determine the achieved steam production at a given fuel consumption and the efficiency of the boiler.

Available heat

Q = 22674 kJ/m 3 .

Fuel consumption

B = 0.77 kg/s.

The amount of heat transferred in the firebox pt = 10425 kW.

The amount of heat transferred in the vapor-forming convective beam k = 5210 kW.

Amount of heat transferred in the economizer eq = 2373 kW.

The total amount of heat transferred to the water in the boiler

1 = Q pt + Q k + Q eq, 1 = 10425 + 5210 + 2373 = 18008 kW.

Feed water enthalpy

i p.v = 377 kJ/kg.

Enthalpy of wet steam

i x = 2695 kJ/kg.

Full (maximum) steam output of the boiler

Q 1 / ( i X - i item c); = 18008/ (2695 - 377) = 7.77 kg/s.

Boiler efficiency

η = 100∙Q 1 / (V p Q);

η = 100 18008/ (0.77 22674) = 100%.

Balance discrepancy:

in thermal units

ΔQ = QηB p - Q 1 (100 - q 4) /100;

ΔQ = 22673 1.00 0.77 - 18008 (100 - 0.5) /100 = 65 kJ;

in percent

δQ = 100∆Q/Q,

δQ = 100 65/22674 = 0.29%< 0,5%.

Bibliography

1. Tomsky G.I. Thermal calculation of a stationary boiler. Murmansk. 2009. - 51 p.

2. Tomsky G.I. Fuel for stationary steam and hot water boilers. Murmansk. 2007. - 55 p.

Esterkin R.I. Boiler installations. Coursework and diploma design. L.: Energoatomizdat. 1989. - 280 p.

Esterkin R.I. Industrial boiler installations. L.: Energoatomizdat. 1985. - 400 p.

Steam boiler low pressure Viessmann with a capacity of 25 t/h, can be used in thermal power plants as a backup source of steam.

Fuel

With given characteristics natural gas:

• CH4 - 98%
• C2H6 - 0.72%
• C3H8 - 0.23%
• C4H10 - 0.10%
• N2 - 0.79%
• O2 - 0.00%
• CO2 - 0.06%
• other - 0.02%

Fuel gas consumption for the backup boiler - 1936 Nm3/hour

Operating overpressure 300 kPa

Oil

Fuel oil consumption – 1236 kg/h

Operating excess oil pressure in front of the burner 400 – 500 kPa

Temperature environment 5-35 C

Main characteristics of the boiler

The specified waste values ​​refer to dry flue gases, pressure 101,325 Pa, temperature 0°C and O 2 content 3% by volume.

Description of the Viessmann boiler

Steel three-pass boiler with a cylindrical combustion chamber and controlled convection heated panels.

The boiler is designed with wide water walls and big step between flame tubes to ensure safety during operation.

The boiler design takes into account a large volume of water, a large space for steam and a large area of ​​the evaporation mirror, as well as a built-in drop separator to improve the quality of steam. Losses due to radiation are not large; this is achieved due to water cooling of the rotating chambers of the wall without lining.

The boiler is placed on longitudinal profiles, which are mounted on concrete foundation. Sound insulation is installed between the profile supports and the foundation. The boiler is manufactured and tested in accordance with Instruction TRD 604. After 1 year of operation it is necessary to carry out internal control boiler

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To ensure safety, the boiler room must be ventilated. The minimum hole for ventilation should have a diameter of 150 cm 2, in addition, for each kW of rated power exceeding 50 kW, it is necessary to provide an increase in the diameter of the hole by 2 cm 2, and the air flow speed should be 0.5 m/s.

Shut-off valves with actuators on the steam line are included in the delivery of the boiler.

In order to prevent an unacceptable increase in pressure, the boiler is equipped with safety valve. Sludge removal is carried out periodically in automatic mode.

Alkalinization occurs continuously and is ensured by a control valve with a servomotor, which is regulated depending on the level of water conductivity in the boiler.

The boiler body is insulated with continuous insulation 120 mm thick.

Operation

The first start-up of the boiler is carried out by a service organization or a person authorized by it. The value settings must be reflected in the measurement report and confirmed at the manufacturer and with the future customer. The boiler can be operated without the constant presence of personnel.

The reserve boiler must be mothballed, like a boiler that is taken out of service for a long period.

When the boiler is idle for a long time, it is necessary to thoroughly clean its surface on the flue gas side. Then preserve the surfaces with preservative oil mixed with graphite.

On the water side, it is recommended to fill the boiler with water purified from gas impurities, with a low salt content and the addition of additives to combine with oxygen. After this, it is necessary to close the shut-off valve on the steam side. The concentration of oxygen sorbents must be monitored at least once a year, and if necessary, more.

It is necessary to inspect it from the outside annually, and control it every three years. internal parts. Every nine years it is necessary to carry out hydraulic tests for strength. Once every six months, inspect all safety and regulatory equipment.

Boiler technical equipment

The boiler also includes:

• pressure regulator with range 0 - 1.6 MPa
• safety valve, DN100/150 in angular design with response pressure 1.0 MPa s throughput 29.15 t/hour.
• feed pump, centrifugal pump high pressure GRUNDFOS type CR 32-8K with electric motor. Water consumption 28.8 m3/hour, lift height 107 m. Minimum pressure height 4.5 m. Feed water temperature no more than 105 °C. Electric motor power 15 kW.
• check valve DN 80, PN16
• water indicator PN 40 with holder, two shut-off valves and one release valve
• boiler level regulator. A level regulator is integrated into the electrical control cabinet of the Viessmann-Control boiler for continuous regulation of the boiler feed water with maximum level limitation and a level switch for limiting the minimum boiler water level.
• shut-off steam valves DN 300, PN 16
• Feed water shut-off valves DN 80, PN16
• feed water control valve
• automatic desalting equipment consisting of a conductivity electrode, a sampling valve and a desalting regulator.
• pressure gauge with a range of 0 – 1.6 MPa
• cooler of selected steam samples with an excess pressure of no more than 2.8 MPa with a valve for the test sample and a valve for cooling the sample.
• pressure limiter in the range 0 – 1.6 MPa
• air vent DN 15, PN 16

Read also: double-circuit exhaust gas recovery boiler

Feed water

Boiler feedwater parameters:

Water should be colorless, clean, without soluble substances

burner

Double burner gas grade WEISHAUPT with O2 regulation for burning liquid fuels in accordance with DIN 51603 or gas in accordance with DVGW worksheet G 260. The burner operates on a rotary atomization principle for high-intensity fuels.

Industrial combined weishaupt burner type WКГMS 80/3-A, ZM-NR with reduced NOx and CO emissions. Version with separate fan, burner body made of light alloys with sectional air valve. Power regulation is two-stage, sliding when using a step regulator and smooth when using a stepper power regulator.

Electronic general control of gas-air combustion with separate servomotors and automatic control of the tightness of gas fittings are integrated into the digital burner control unit. The microprocessor-controlled digital burner automation W-FM 100 is designed to control and monitor all burner functions.

A dual fuel gas/fuel oil burner must be tested in accordance with the instructions for gas and oil burners. The oil burner must be tested and marked in accordance with EN 267 and TRD 411. Gas burner must be tested in accordance with EN 676 and marked in accordance with Directive 90/396/EWG with the CE mark and TRD 412.

The connection of the burner to the boiler will be carried out at the manufacturer's factory.

The fuel oil or gas flow rate setting must be such that the maximum thermal output of the boiler is not exceeded.

air fan

The combustion air is equipped with an air fan with a noise suppressor, a fan-air duct compensator, and a protective mesh on the suction side. The fan is installed in an anti-noise box, which reduces general noise from fan operation to a level of 80 dB. The air duct is routed to the burner through a channel. An integral part The burner valve is a control valve connected to the burner inlet flange.