RU2619429C1 - Method of contact heat exchange and device for its implementation - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: contact heat exchange method comprises the heat transfer between the gaseous combustion products and the surface of the liquid, in which the heat transfer by contact heat organize field torch with water in a dropping state by the primary storage in the entire plume vaporization energy of the water droplets in a volume of ~ 4.7% the total weight of the heated water and the subsequent intensive energy exchange resulting gas mixture adhesive-condensing heat exchange with the bulk water drops in the amount of ~ 94.3%. Hot water boiler for implementing the method comprises a burner device, the feed water supply device, a combustion chamber, which comprises a mixing chamber, swirl, irrigation chamber, the separator, the water separator.

EFFECT: intensification of heat transfer with increasing boiler efficiency.

5 cl, 2 dwg

Description

The invention relates to methods of contact heat transfer between the thermal field of fuel combustion products and water, as well as to devices for its implementation, to boilers of contact-type heat exchange condensation-type heat exchange.

A known method of heat exchange between the thermal field of the products of fuel combustion and water and a device for its implementation - contact water heater air-lift type [Kuchukhidze DG Development and research of contact water heaters with cyclone furnaces. Diss. for the degree of Cand. tech. sciences].

A disadvantage of the known method is that heat exchange between the combustion products and the liquid occurs on surfaces limited by the internal geometry of the device, which significantly reduces the heat transfer rate, and the presence of airlift tubes complicates the design of the device for implementing the method and increases its material consumption.

The known method [AC 347530 (USSR). The method of heating the liquid. B.M. Teperikov, L.A. Mipukhin], in which heat is exchanged over the surface of the liquid, while the total amount of fuel required to heat the liquid, such as sea water, is divided into several parts, which are burned in separate steps connected in series along the heated liquid. Also known is a thermal immersion combustion unit [AC 391360 (USSR) I.L. Tenenbaum], which works as follows. With the help of a starter, the engine is started. The fan which is turned on at the same time pumps air into the compressor, diffuser and combustion chamber of the submersible burner. The air compressed in the compressor is directed into its combustion chamber, in which the fuel supplied to it through the nozzle burns. Gases enter the turbine from the combustion chamber. The high-temperature gases leaving the turbine enter a diffuser, in which their speed decreases to a value at which it is possible to burn fuel, and the gas static pressure rises to a value equal to the air pressure after the fan. Here, in the diffuser, gas is mixed with air coming from the fan along the annular gap and through the openings. Toward the flow of the air-gas mixture through the nozzles is sprayed liquid fuel. The resulting fuel-air mixture is sent to the combustion chamber of the burner, where also the air necessary for combustion enters the annular gap from the fan through radial openings. Air flows through the axial holes from the annular gap for film cooling of the wall of the combustion chamber of the burner, where the initial ignition of the fuel-air mixture is carried out using the starting burner. Further continuous ignition of the mixture occurs due to reverse current zones arising behind ring stabilizers. The combustion products enter the reflector through the exhaust pipe, change their direction and sparge through a layer of liquid, giving it their heat.

The disadvantages of the known method and device is that:

- part of the energy is spent on continuously overcoming the static pressure of the bubbler fluid column;

- heat transfer between the combustion products and the liquid comes from the heat accumulated in the gas bubbles of the combustion products having a very low radial heat conductivity and, therefore, reduced heat transfer during their bubbling, which significantly reduces the heat transfer intensity.

Closest to the proposed device is a contact water heater [AC 376636 (USSR). Contact water heater. Yu.P. Sosnin], in which the heated water enters through the pipe into the lower zone of the casing and gradually rises up. At the shield level, the flue gases formed in the combustion chamber enter the liquid layer with high speed through the gap. A gas jet having a certain kinetic energy breaks into many small bubbles upon impact with water, as a result of which, presumably, a developed interfacial surface is created through which heat and mass transfer between gases and water occurs. Bubbles of gases, floating up under the influence of gravitational forces, entrain nearby water layers. The gas-liquid emulsion rises and in its upper zone hits the reflector. In this case, the two-phase gas-liquid system is destroyed. Gas in the form of combustion products and water vapor rises, and heated water enters the collector and then spills by gravity to consumers.

A disadvantage of the known device is that the formation of small droplets is not intensive enough when the gas stream hits the surface of the water (the media have an approximately 800-fold density ratio), and the creation of high kinetic energy of the jet using the blower of the burner cannot be obtained due to the low pressure developed by the fan, the increase in fan power is limited by the compressibility of the gases, which will require additional energy. All this does not allow to properly prepare the conditions for intense interfacial heat transfer.

The technical result of the claimed invention is optimization of heat transfer with increasing boiler efficiency, reducing material consumption, size, cost of the boiler, its maintenance and increasing its environmental friendliness and safety of operation.

The specified technical result is achieved by the method of contact heat transfer and a device for its implementation, in which the fuel (liquid or gaseous) is supplied to the burner, in which it is mixed with the supplied air (excess air is determined by the characteristics of the burner depending on the type of fuel burned) and is flared . Feed water is sprayed through the nozzles of the evaporative circuit using a feed pump into the flame flame and tangentially with droplet size d ₁ ≤0.2 mm in the amount of ~ 4% of the total mass of circulating water. These drops perform a threefold function: drip cooling of the wall of the burner combustion chamber; radiation shield of the thermal field of the torch; a source of vapor-gas medium for subsequent adhesive-condensation heat transfer. The resulting vapor-gas mixture, expanding, is mixed with a swirl in the mixing chamber and enters the irrigation chamber of the combustion chamber. Using the feed pump, the remaining mass of feed water (~ 96%) is fed into the mixing chamber of the combustion chamber by flow through the nozzles of the heating circuit and the droplet size d ₂ ≥0.4 mm. Nutrient irrigation water is supplied tangentially with washing the walls of the combustion chamber irrigation chamber to prevent its overheating. The process of heat and mass transfer proceeds intensively, because a high-energy vapor-gas mixture intensively contacts with drops of irrigation, condensing on drops of a colder related drop liquid, which is in a finely dispersed state. Heated water flows into the water collector, from which it is supplied to the consumer by a network pump. The sludge accumulated in the lower part of the catchment is removed with a purge. Exhaust flue gases are cleaned of moisture droplets in a separator-water separator and are removed to the atmosphere. Harmful gas emissions (СО, СО ₂ , nitrogen oxides) are absorbed by water for their further release. This ensures the intensity of contact heat and mass transfer between the thermal field of the products of combustion of fuel and water.

Feed nozzles with an average droplet size d ₁ ≤0.2 mm (by the condition of complete evaporation) are sprayed tangentially through the nozzles of the evaporation circuit using the feed pump into the flame plume in the amount of ~ 4% of the total water mass. These drops, at a negligible cost to obtain them, perform the following set of functions:

- high-quality radiation shield of the thermal field of the torch with a degree of blackness ~ 0.94 ... 0.96;

- a converter of the radiation spectrum of a flame plume with a temperature of ~ 1300 K - immediately to a medium with a temperature of ~ 400 K, at which the initial highly radiative process, proportional to the fourth degree absolute temperature according to the Stefan-Boltzmann law (T ⁴ ), decreases by about 3.25 ⁴ times, i.e. translates into exclusively convective;

- a highly effective convective heat transfer agent between the gaseous medium formed by combustion, water droplets and their vapor;

- drip-steam protective environment for cooling the walls of the burner;

- a highly dynamic and energy-intensive steam-gas medium, an accumulator of all torch energy with a developed contact surface, significantly larger than that of the torch flame itself;

- high-speed spatial carrier of accumulated energy to the zone of subsequent heat exchange with drops of irrigation water;

- adhesive-condensation exchange of accumulated energy with a larger surface of subsequent irrigation drops at the final stage of energy exchange.

The resulting vapor-gas mixture, expanding, is mixed with a swirl in the mixing chamber of the combustion chamber and enters the irrigation chamber of the combustion chamber. In this case, the gas-vapor mixture contains the total energy reserve:

- thermal, obtained from the thermal field of the torch (radiation and convective);

- the energy of the development of the surface of the primary drops obtained from the feed pump.

The amount of supply of feed water to the nozzles of the evaporative circuit is determined by the requirement of its complete evaporation, based on the heat balance of the boiler, determined for a unit flow rate of the coolant by the ratio:

c (t _r -t _o ) = r * q,

where c is the heat capacity of water, s = 4200 J / (kg * K);

t _g and t _o are the hot water temperature and return water temperature, respectively, t _g = (273 + 95) K and t _o = (273 + 70) K;

r is the latent heat of vaporization of water at atmospheric pressure, r = 2.5 * 10 ⁶ J / kg;

q is the mass fraction of the supply of feed water to the nozzles of the evaporation circuit.

Then the mass fraction at the maximum water temperature in the return pipe of the boiler (return network water) equal to 70 ° C:

q = c (t _g -t _o ) / r = 4200 (95-70) / 2.25 * 10 ⁶ = 0.0467 = 4.7%.

The remaining mass of feed water (~ 95%) is fed into the irrigation chamber of the combustion chamber with the help of a feed pump through a nozzle sprayed onto droplets of size d ₂ ≥0.4 mm, according to the condition of non-evaporation. Nutrient irrigation water is supplied tangentially with two tasks:

- forced washing of the walls of the irrigation chamber to prevent overheating;

- vortex intensification of the heat and mass transfer process with vapors of the evaporated part of the water, accumulating all the energy of the combusted fuel.

Since in the irrigation chamber of the combustion chamber heat and mass transfer of related media occurs: steam-gas mixture with a temperature of about 100 ° C and fine droplets of irrigation water with a temperature of about 70 ° C, with high mutual adhesion, the vapor component of the gas-vapor mixture condenses on the drops of irrigation, exchanging energy with the rest mass of water, summing up and heat of the adhesive-condensation conversion. The gas component is absorbed by the colder surface of the irrigation droplets. Thus, all energy costs are converted to heat in the feed water. Further, the energy costs of the feedwater pump for the development of the surface of the irrigation droplets are also transferred to the heat of water in the return pipe of the boiler at the end of the process with concentration coalescence of the droplets into the flow of network water, as a result of which there is a complete separation into two macrophases: liquid - gas.

Evaluation of energy consumption for droplet formation [Energy dispersion and condensation. P. 115] [The surface tension of liquids and aqueous solutions. S. 428, Appendix 5].

A) The rationale for the low cost of obtaining drops of water

1. The volume of a single drop on:

- evaporation at d ₁ ~ 0.2 mm

- irrigation at d ₂ ~ 0.4 mm

2. The mass of a single drop (ρ = 10 ³ kg / m ³ ):

- for evaporation:

m ₁ = ρ⋅V _K1 = 10 ³ ⋅4.19⋅10 ^-12 = 4.19⋅10 ^-9 kg;

- for irrigation:

m ₂ = ρ⋅V _K2 = 10 ³ ⋅3.35⋅10 ^-11 = 3.35⋅10 ^-8 kg.

3. The number of drops formed every second when:

- d ₁ ~ 0.2⋅10 ^-3 m and 0.047⋅G _m kg / s,

where G _m is the mass flow rate of network water of the heating system for heating from a temperature of 70 ° C to a temperature of 95 ° C, kg / s;

- d ₂ ~ 0.4⋅10 ^-3 m and 0.953⋅G _m kg / s

4. The surface of a single drop with:

- d ₁ ~ 0.2⋅10 ^-3 m

- d ₂ ~ 0.4⋅10 ^-3 m

5. Surfaces that are developed every second by drops with:

- d ₁ ~ 0.2⋅10 ^-3 m

ΣS ₁ = n ₁ ⋅S ₁ = 11.22⋅10 ⁶ ⋅1.26⋅10 ^-7 ⋅G _m = 1.4⋅G _m m ² ;

- d ₂ ~ 0.4⋅10 ^-3 m

ΣS ₂ = n ₂ ⋅S ₂ = 28.44⋅10 ⁶ ⋅5.03⋅10 ^-7 ⋅G _m = 14.3⋅G _m m ² .

6. Every second, the energy spent on the development of the surface of the droplets when:

- ΣS ₁ = 1.4⋅G _m m ²

ΣW ₁ = σ⋅1.4⋅G _m = 0.073⋅1.2⋅G _m = 0.1⋅G _m J / s;

- ΣS ₂ = 14.3⋅G _m m ²

ΣW ₂ = σ⋅ΣS ₂ = 0.073⋅14.3⋅G _m = 1.04⋅G _m J / s.

7. The total energy consumption for the droplet formation of all feed water:

ΣW = ΣW ₁ + ΣW ₂ = G _m (0,1 + 1,04) = 1,14⋅G _m J / s.

8. If we bring these calculations to a typical quarterly boiler house, in particular, with a capacity of W = 14 MJ / s, which has four boilers with a capacity of 3.5 MW each, we obtain that for every second conversion of heat energy 14⋅10 ⁶ J / s into energy evaporation of droplets with a mass of Σm ₁ and d ₁ ~ 0.2⋅10 ^-3 m requires a mass flow rate of network water:

where r is the heat of vaporization of water, equal to 2.25⋅10 ⁶ J / kg.

9. According to the application, ΣGm ₁ = 0.047⋅G _m . From here

10. The total mass of irrigation drops formed every second is:

ΣGm ₂ = Gm-ΣGm ₁ = 132.3-6.22 = 126.1 kg / s.

11. The total energy consumption, taking into account clause 7, will be:

ΣW = 1.14 * G _m = 1.14⋅126.1 = 143.8 J / s = 143.8 W,

which can be neglected in comparison with the boiler room power of 14⋅10 ⁶ W, because they will be approximately 1.03⋅10 ^-9 %. However, with the adhesive-condensation heat transfer proposed in the application, even this energy (ΣW) will be returned to the heat supply system, increasing the overall efficiency of the boiler.

All this together successfully recuperates all preliminary costs, increasing the overall efficiency of the process of heating water.

B) Justification of the effectiveness of shielding and perception of radiation from a flame plume

1. The volume of the full drip cylinder of the combustion chamber:

_C.c V = V _c -V _f = 0,25 * π * l _c * (d _c -d ² ₌ ^2), m ^3,

where l _cg is the length of the combustion chamber (flame);

d _cg is the inner diameter of the combustion chamber or the outer diameter of the drip cylinder;

d _f - the outer (visible) diameter of the torch or the inner diameter of the full drip cylinder;

V _cg is the internal volume of the combustion chamber or the volume of the drip cylinder;

V _f - external (visible) volume of the torch or the volume of a full drip cylinder;

Δd _k.c is the _half -difference of the diameters of the ends of the complete drip cylinder,

Δd _K.c = 0.5 * (d _cr -d _f );

n _c - the number of elementary coaxial cylinders from the partition of the radial thickness - Δd _k.ts full drip cylinder.

2. The number of droplets formed from a 4.7% mass water flow rate for evaporation of 0.047 * G _m :

n ₁ = 0.047 * G _m / m ₁ = 0.047 * G _m / (1/6) (ρ * π * d _to ³ ) = 0.282 * G _m / ρ * π * d _to ³ , pcs.,

where G _m is the mass flow rate of network water for heating it from 70 ° C to 95 ° C, kg / s;

ρ is the density of water, kg / m ³ ;

d _to - the diameter of the droplets of the dropping cylinder, m

3. The volume concentration of water droplets in a complete drip cylinder of paragraph 1:

C ₁ = n ₁ / V _c.c = (0.282 * G _m / ρ * π * d _c ³ ) / 0.25 * π * l _cg * (d _cg ² -d _f ² ) = 1.128 * G _m / ρ * π ² * d _to ³ * l _cg * (d _cg ² -d _f ² ), 1 / m ³ ,

where V _k.ts - part of the volume of the combustion chamber occupied by the full drip cylinder, item 1, m ³ .

4. Linear droplet concentration - the number of droplets along any linear measurement in the cylinder: radius, circumference of the arc, length of the combustion chamber

C ₂ = [1.128 * G _m / ρ * π ² * d ₁ ³ * l _cg * (d _cg ² -d _f ² )] ^1/3 . 1m

5. The number of drops per linear radial width Δd _{k.c of the} end ring of the complete drip cylinder of FIG. 1, i.e. on Δd _K.c = 0.5 * (d _cr -d _f ):

n _k = C ₂ * Δd _c = [0.141 * G _m * (d _cg- d _f ) ² / ρ * π ² * d _to ³ * l _cg * (d _cg + d _f )] ^1/3 .

6. The surface concentration of droplets on the side surface of each elementary coaxial droplet cylinder

C ₃ = C ₂ ² = [1.128 * G _m / ρ * π ² * d _to ³ * l _cg * (d _cg ² -d _f ² )] ^2/3 , 1 / m ² .

7. Through each of the drops n _k (p. 5) we draw an imaginary elementary coaxial drop cylinder of length - l _c with the surface concentration of C ₃ drops (p. 6), that is, we get n _c = n _k (p. 5) - the number of such elementary drop cylinder-surfaces embedded in each other with a thickness of the lateral cylindrical wall equal to the diameter of the drop.

The radiation component of the flame will be directed from the inside of the entire coaxial set of elementary cylinders-surfaces - through their side surfaces to the wall of the combustion chamber (Fig. 1). A receiver-absorber of this radiation component of the torch and a radiation screen for the wall of the combustion chamber will be a set of drops on the surfaces of all n _c (item 5) of elementary coaxial cylinders. Since the surface concentration of droplets on the lateral (cylindrical) surface of each elementary i-th droplet cylinder is constant and equal to - C ₃ , the number of droplets on the surface of the i-th cylinder depends only on the diameter of the i-th cylinder itself.

If n _cb = C ₃ * S _bc is the number of drops of the lateral surface of each of the elementary coaxial cylinders, then we can write the ratio of the total area of the projection of the drops (Middel section - S _ave. * C ₃ * S _b.c ) on the lateral surface of the cylinders to the area of the very lateral surface. The projection area of a spherical drop on the surface

S _pr.k = 0.25 * π * d _to ² .

We compose the ratio of the sum of the projection areas of all the drops of an elementary dropping cylinder onto its lateral surface - χ:

χ = S _ave. * C ₃ * S _b.c / S _b.c = S _ave. * * ₃ ,

those. χ = S _pr.k * C ₃ ,

then χ = S _pr.k * C ₃ = 0.25 * π * d _to ² * [1,128 * G _m / ρ * π ² * d _to ³ * l _cr * (d _cg ² -d _f ² )] ^{2 / 3} = 0.27 * G _m ^2/3 / ρ ^2/3 * π ^1/3 * l _cg ^2/3 * (d _cg ² -d _f ² ) ^2/3 .

8. Since all n _c.c. (item 7) of coaxial droplet cylinders overlap each other with their lateral cylindrical surfaces, the screening of the radiation flux is the result of their collective screening effect. Taking into account the fact that the “pictures” of the location of the droplets on the lateral surface of all n _K. cylinders are not correlated with each other and are a probabilistic process, in such cases χ _res is defined as the mathematical expectation, namely:

Here: χ _res = 1 - based on the desire to provide 100% shielding of the radiation flux, n _c ^0.5 = [0.141 * G _m * (d _cg -d _f ) ² / ρ * π ² * d _to ³ * l _cg * (d _cg + d _f )] ^1/6 .

The maximum permissible droplet diameter, providing 100% shielding, is determined from the last expression

0.286 * G _m ^5/6 / ρ * π ^7/3 * d ₁ ³ * l _cg ^5/3 * (d _cg ² -d _f ² ) ^1/3 * (d _cg + d _f ) ^1/6 = 1 , namely

d _c.max = _0.286 * G _m ^5/6 / ρ * π ^7/3 * l _cg ^5/3 * (d _cg ² -d _f ² ) ^1/3 * (d _cg + d _f ) ^1/6 ,

we get for one boiler G _m = 31.53 kg / s, ρ = 1000 kg / m ³ , l _cg = 1.7 m, d _cg = 1 m, d _f = 0.5 m, then

d _k.max = _0.286 * 31.53 ^5/6 / 1000 * π ^7/3 * 1.7 ^5/3 * (1 ² ⋅0.5 ² ) ^1/3 * (1 + 0.5) ^{1 / 6} = 361 * 10 ^-6 m = 0.361 mm.

Having grouped in the expression for d _{to the} terms depending on the boiler capacity in separate square brackets, and the independent ones in separate round brackets, we obtain:

d _k = 0.286 * G _m ^5/6 / ρ * π ^7/3 * l _cg ^5/3 * (d _cg ² -d _f ² ) ^1/3 * (d _cg + d _f ) ^1/6 = (0.286 / ρ * π ^7/3 ) * [G _m / l _cr * (d _cg ² -d _f ² ) ^1/3 * (d _cg + d _f )].

Note that in the factor [G _m / l _cg * (d _cg ² -d _f ² ) ^1/3 * (d _cg + d _f )] ^1/6 ] the numerator and denominator, oppositely varied values as a function of the boiler power, then there is, this ratio is slightly variable, and therefore we use the obtained value d _to.max ~ 0.36 mm as the base. Those. with, in particular, a ~ 2-fold decrease in the diameter of the droplet to d _to ~ 0.2 mm or less, we will ensure a guaranteed χ _res . Reducing the diameter of the droplet is desirable in terms of avoiding gravitational separation of the droplets and facilitating Brownian soaring of the droplets in the heat field of the torch and subsequent heat exchange with irrigation drops.

χ _res = 0.286 * G _m ^5/6 / ρ * π ^7/3 * d ₁ ³ * l _cg ^5/3 * (d _cg ² -d _f ² ) ^1/3 * (d _cg + d _f ) ^{1 / 6} = 1.

This will provide a high coefficient of exergy of the process of accumulation of radiation energy in the sprayed droplets around the flame of the combustion chamber. A high shielding factor is important because allows you to compensate for the non-unity of the real degree of blackness of water ε ~ 0.94, especially since in water there is a known transparency window for rays with a wavelength of λ = 9 ... 12 μm. The real situation with absorption is even better, because regular circulating network water is usually turbid, i.e. has a high degree of blackness.

A device for implementing the method is a contact-type hot-water boiler including a burner device, feed water supply device, a combustion chamber containing a mixing chamber, a swirler, an irrigation chamber, a separator-water separator, where heat exchange is organized by optimizing contact of the heat field of the torch with water in the dropping state by means of the primary accumulation of all torch energy (radiation and convective components) in the heat of vaporization of droplets (d ₁ ≤0.2 mm) of water in a volume of ~ 4.7% of the total mass of heated water with the formation of a dynamic vapor-gas mixture and the subsequent intensive energy exchange of the gas-vapor mixture by adhesive-condensation heat transfer with drops (d ₂ ≥0.4 mm) of the bulk of the water in a volume of ~ 94.3%. When the vapor-gas mixture is intensively contacted with irrigation drops, the primary drops condense on drops of a related drop liquid. In the separator-water separator, as a result of the oncoming movement of the flue gases and feed water supplied to the separator-water separator, partially carried away droplet moisture and moisture condense from the flue gases are separated when the temperature of the flue gases drops below the temperature of the dew point of the moisture contained in the vaporized flue gas gases. The amount of feed water supplied to the separator-water separator is determined by the heat balance and is approximately 1% of the total feed water flow.

As a result: the boiler efficiency increases due to the use of condensation heat of water vapor contained in flue gases; the material consumption of the boiler and its cost are reduced due to a decrease in its dimensions with more intense heat transfer; requirements for feed water quality are reduced in terms of scale formation on heating surfaces, as the heating surface is water droplets and scale forms in the form of sludge that is removed by blowing; environmental friendliness increases due to washing with droplets of irrigation water flue gases absorbing harmful gas emissions (СО, СО ₂ , nitrogen oxides); increased operating safety, as the boiler body is not under pressure. The resulting harmful liquid effluents are substantially more easily, cheaper and more localized in comparison with gas emissions for the purpose of their local disposal or return to the chemical industry.

In FIG. 2 shows a schematic diagram of a boiler for contact heating. The scheme includes the following elements: 1 - combustion chamber, 2 - mixing chamber, 3 - irrigation chamber, 4 - burner, 5 - fuel supply, 6 - air supply, 7 - flame, 8 - feed water, 9 - spray nozzles combustion chambers, 10 - drip evaporated water, 11 - flow of droplets, 12 - swirl, 13 - feed pump, 14 - irrigation nozzles, 15 - return network water, 16 - supply of feed water to the nozzles, 17 - water separator, 18 - sump, 19 - mains pump, 20 - hot mains water, 21 - sludge purge, 22 - exhaust flue gases.

The method is as follows.

Fuel 5 (liquid or gaseous) is supplied to the burner 4, in which it is mixed with the supplied air 6 (excess air is determined by the characteristics of the burner depending on the type of fuel burned) and is flared. Around the flame plume 7, feed water 8 is dripped and tangentially injected through the spray nozzles of the combustion chamber 9 by the drip of evaporated water 10 of the combustion chamber 1 by means of the feed pump 13 forcing the return network water 15 to supply the feed water to the nozzles 16 for:

- drip-evaporative cooling of the wall of the combustion chamber 1 and burner 4;

- absorption of the radiation component of the thermal field of the plume - radiation screen;

- steam formation (average droplet size over the fullness of evaporation d ₁ ≤0.2 mm) - the formation of an energy-intensive phase state of water related to subsequent irrigation water.

The resulting expanding vapor-gas mixture is mixed by means of a swirler 12 located in the combustion chamber along the way through the mixing chamber 2 of the combustion chamber into the irrigation chamber 3 of the combustion chamber. Feed water 16 is supplied to the irrigation chamber 3 of the combustion chamber through the irrigation nozzles 14 of the heating circuit using a branch from the feed pump 13. The sprayed feed water is introduced tangentially by washing the walls of the irrigation chamber 3 to prevent it from overheating. The process of heat and mass transfer proceeds intensively, because the gas-vapor mixture is in contact with a related and colder droplet liquid in a finely dispersed state, droplet sizes to minimize evaporation d ₂ ≥0.4 mm. Heated water flows into the water collector 18, which is a water trap and a sludge separator, from which the network pump 19 is supplied to the consumer in the form of network hot water 20. The sludge accumulated in the lower part of the water collector 18 is removed with a purge 21. The exhaust flue gases 22 are cleaned of moisture and moisture droplets, condensed from the flue gas when the temperature of the flue gas drops below the temperature of the dew point of the moisture contained in the vaporized flue gas in the separator-water separator 17 located at the outlet of the combustion chamber, and removed I was in the atmosphere. Harmful gas emissions (СО, СО ₂ , nitrogen oxides) are absorbed by water.

An example of the method

The contact heating water-heating boiler is designed to produce hot water with a temperature of not more than 95 ° C for heat supply needs. The temperature of the return network is not limited by the lower limit (in ordinary boilers, the temperature of the return network water is limited to a temperature of 70 ° C, which is associated with the prevention of condensation on the tail surfaces of the heating). In the proposed method, the temperature of the return network water can be lower than 70 ° C, depending on the consumer.

Feedwater is sprayed through the tangential nozzles of the evaporation circuit using a feed pump into the flame plume with an average droplet size d ₁ ≤0.2 mm under the condition of complete evaporation in an amount of ~ 4.7% of the total water mass. The temperature of the flue gases decreases and the walls of the combustion chamber of the burner and the boiler body do not overheat.

The bulk of feed water (~ 94.3%) is fed into the irrigation chamber of the combustion chamber by flow through nozzles with tangential spraying onto droplets of size d ₂ ≥0.4 mm (under the condition of non-evaporation) using a feed pump. The heat carrier is heated by a gas-vapor mixture to a temperature of 95 ° C in an irrigation chamber. With direct contact of liquid droplets and gas flow, the heat transfer coefficient reaches 20 ... 50 kW / (m ² * K), and the heat transfer surface depends on the required degree of atomization (torch parameters) determined by the nozzle design.

The calculation and selection of nozzles and the determination of the geometric dimensions of the apparatus (torch height) are based on experimental data [V. Galustov. Direct-flow spraying apparatus in the power system. - M .: Energoatomizdat, 1989. - 240 p.)].

Flue gases are removed through the chimney, passing first through a separator-water separator located at the outlet of the combustion chamber. In the separator-water separator as a result of the oncoming movement of flue gases and feed water supplied with a flow rate of ~ 1% of the total feed water flow rate, in particular, on a perforated (perforated) sheet, entrained droplet moisture and moisture condensed from the flue gases are separated with a decrease flue gas temperatures are below the dew point temperature of the moisture contained in the vaporized flue gas. The height of the chimney can be reduced due to increased environmental friendliness of gas emissions.

Feed water is supplied to the nozzles by a centrifugal feed pump under normalized nozzles with a pressure of 0.15-0.3 MPa or more. The distribution of water flows is carried out by selecting the total nozzle cross-section in accordance with a given ratio of flow rates.

The flue gases have a temperature below 70 ° C, which is lower than the temperature of the flue gases for conventional boilers (110-140 ° C is recommended depending on the characteristics of the fuel and the capacity of the boiler). In this regard, heat losses with flue gases are reduced and, accordingly, efficiency is increased (lowering the temperature of the flue gases by 12-15 ° C increases the efficiency by about 1%). It is also possible to increase the efficiency of the boiler by utilizing the heat of condensation of the water vapor of the flue gases using the higher calorific value of the fuel, which can additionally increase the efficiency of the boiler by 5-6%.

The sludge accumulated in the lower part of the collector is purged and part of the water that accumulates as a result of condensation of water vapor from the flue gas is removed.

Claims (5)

1. The method of contact heat transfer, including heat exchange between the gaseous products of fuel combustion and the surface of the liquid, characterized in that the heat exchange is organized by contacting the heat field of the torch with water in a droplet state through the primary accumulation of all the energy of the torch in the evaporation of droplets of water in a volume of ~ 4.7 % of the total mass of heated water and the subsequent intense energy exchange of the resulting vapor-gas mixture by adhesive-condensation heat transfer with drops of the bulk of the water in a volume of ~ 94.3%. 2. The method according to p. 1, characterized in that the size of the water droplets is set for evaporation d ₁ ≤0.2 mm for maximum evaporation, and for irrigation - d ₂ ≥0.4 mm for minimum evaporation. 3. The method according to p. 1, characterized in that the bulk of the drop water, ~ 94.3%, is introduced along the walls of the irrigation chamber with tangential washing of the walls. 4. The method according to p. 1, characterized in that the exhaust flue gas is washed with feed water in a volume of ~ 1% of the total feed water flow. 5. A hot water boiler for implementing the method according to claim 1, comprising a burner device, a feed water supply device, a combustion chamber, characterized in that the combustion chamber comprises a mixing chamber, a swirler, an irrigation chamber, a separator-water separator.

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