RU2309332C1 - Multifunctional burner - Google Patents

Abstract

FIELD: heat and power industry; other industries; production of the multifunction burners.

SUBSTANCE: the invention is pertaining to the heat and power industry and may be used in the boilers of the heat power plants burning the gas and the coal dust, for reduction of the present nitrogen oxides, and for improvement of the performance and reliability. The multifunctional burner contains: the thermoprotective body with the upright-slit separated by partition and the conditional vertical plane of symmetry the air-dust withdrawing and the main air-withdrawing windows having the internal and external vertical walls, the ceiling and the hearth floors; the main gas-release nozzles located in the body under the dust-withdrawing window additional air withdrawing nozzle and the main gas-release nozzles placed beyond the overall dimensions of the windows composed in the vertical rows and mounted in the body at an angle to the conditional vertical plane of the symmetry of the burner along the external wall of the main air-withdrawing window and also the additional gas-release nozzles. At usage of the device the installation angle of the main gas-release nozzles is equal to 2.5-9.5 degree. The additional gas-release nozzles also are composed in the vertical rows, put beyond the overall dimensions of the windows, but installed along the external wall of the dust-withdrawing window at then angle to the conditional vertical plane of the symmetry of the burner equal to 5.5-20.5 degrees. The invention allows to increase the effectiveness of burning of the coal of the lower quality, especially with the low output of the volatile substances, to reduce concentration of nitrogen oxides in the flue gases, to diminish incomplete burning and to increase thermal stability of the fuel-air withdrawing windows and nozzles of the multifunctional burner.

EFFECT: the invention ensures the increased effectiveness of burning of the lower quality coal, especially the cal with the low output of the volatile substances, to reduce concentration of nitrogen oxides in the flue gases, to diminish incomplete burning and to increase thermal stability of the fuel-air withdrawing windows and nozzles of the multifunctional burner.

5 dwg

Description

The invention relates to energy and can be used in combustion technology on boilers of thermal power plants that burn gas and coal dust.

Known dust-and-gas multifunctional burner, comprising a housing, vertical slotted dust-exhaust and main air-outlet windows separated by piers, placed below and above the dust-exhaust window, additional air-exhaust nozzles arranged in vertical rows of gas-exhaust nozzles, and also air-exhaust and dust-exhaust ducts, windows (patent RU No. 2228491, IPC F23D 17/00 of 04/15/2003, BI No. 13, 2004). The burner implements modes with a reduced yield of nitrogen oxides in the combustion products. The disadvantage of the burner, as shown by operating experience, can be attributed to the need to select the installation site of the exhaust nozzles in the main air outlet windows to increase the heat resistance of the burner depending on the specific size of the elements and the type of solid fuel burned. When switching to burning fuel with non-calculated thermophysical characteristics together with gas in the exhaust section of the burner, large heat fluxes can occur in the direction of the wiring, activating the thermal destruction of the latter.

Known dust-gas burner containing an axisymmetric window for the output of dust and air flows, dust-air supply and air supply channels connected to the window, as well as gas exhaust nozzles placed outside the window dimensions and inclined to the central axis of the burner (USSR author's certificate No. 1163088, IPC F23C 1/12 from 04.04.83, BI No. 23, 1985). The burner allows you to organize the joint burning of gas and dust of solid fuel of deteriorated quality with a reduced underburning of the latter. The disadvantage of the burner is the low reliability of the metal structures of the dusty air outlet assemblies in the window and inlet ducts during joint combustion of gas and dust, as well as the high concentration of nitrogen oxides in the exhaust gases.

A dust and gas burner is also known, which contains an axisymmetric window for discharging dust and air flows, inlet ducts and dust pipes connected to the window, as well as main and additional gas outlet nozzles built into the air outlet window (Shnitser I.N. Study of the combustion process when burning non-project anthracite separately and together with gas // Journal "Heat Power Engineering", 1988, No. 1, pp. 16-22). The burner allows you to burn solid fuel dust with gas at a reduced degree of underburning. The disadvantage is the high yield of nitrogen oxides in the combustion products, as well as the insufficiently high reliability of the burner metal structures.

Known dust and gas burner containing vertically slit, separated by a wall and a conventional vertical plane of symmetry, dust and air exit and exit windows having external and internal vertical walls, ceiling and hearth ceilings, arranged in a vertical row and installed in the air exit window along its outer wall at an angle to vertical plane of symmetry ~ 20.7 deg gas exhaust nozzles (Guiding technical material. Direct-flow pulverized coal, dust and gas burners and their arrangement with the furnace and. The methods of calculation and design. 108.030.120-78 RTM. Official publication. Drawing 14, p.29). By installing exhaust nozzles arranged in a vertical row in the air outlet window, the yield of nitrogen oxides with combustion products is reduced. The disadvantage of the burner is its low reliability due to the active burning of metal structures and the destruction of the lining, especially when co-burning pulverized coal gas.

A gas burner is known that contains a ceramic heat-shielding case with vertically slit gas-venting windows separated by piers, a conditional vertical plane of symmetry passing through the body of the housing, an air duct connected to the housing windows and gas exhaust nozzles built into it (D.M. Khzmalyan, Y.A. Kagan, Combustion Theory and Furnace Devices, Moscow: Energy, 1976, p. 175, fig. 9-16; fig. 9-17). The implementation of the burner body with the fuel air outlet and nozzles in a heat-shielding design increases the thermal stability of the structure, increases the reliability of the furnace and burner assemblies, and extends the overhaul period. The disadvantage of the burner is a high yield of nitrogen oxides with combustion products.

The objective of the present invention is to increase the efficiency of burning coal of deteriorated quality, especially with a low yield of volatile substances, with a reduced concentration of nitrogen oxides in flue gases, reduced undercooking and increased heat resistance of fuel-exhaust windows and nozzles of a multi-function burner.

To solve this problem, in a multifunctional burner containing a heat-shielding case with vertically slit, separated by a wall and a conditional vertical plane of symmetry, dust-exhaust and main air-exit windows, having external and internal vertical walls, ceiling and hearth ceilings, an additional air-outlet placed in the housing under the dust-air exit window nozzle placed outside the window dimensions, arranged in vertical rows and installed in the housing at an angle to the conventional vertical according to the invention, the installation angle of the main gas outlet nozzles is α ₁ = 2.5-9.5 degrees, and the additional gas outlet nozzles are also arranged in vertical rows, taken out of the dimensions of the embrasure windows, but installed along the outer wall of the dusty air outlet window at an angle to the vertical plane of symmetry of the burner equal to α ₂ = 5.5–20.5 degrees.

The removal of gas exhaust nozzles beyond the dimensions of the air outlet window eliminates the possibility of early ignition of gas and the spread of off-design large heat fluxes into the burner and connected air supply ducts and dust pipes, regardless of the type of fuel burned, which increases the reliability of the device, prolongs its service life, and reduces the amount of necessary repairs. By installing the main gas outlet nozzles at an angle α ₁ = 2.5–9.5 degrees to the conditional vertical plane of symmetry of the burner, the optimal combustion regimes for the output of nitrogen oxides, carbon monoxide and chemical underburning of the fuel are achieved. By installing additional gas outlet nozzles along the outer wall of the dusty exhaust window, arranging them in vertical rows, the reliability of the burner elements — its windows and adjacent ducts and dust ducts — is increased regardless of their design dimensions and type of fuel burned. By turning additional gas outlet nozzles to the vertical plane of the burner α ₂ = 5.5-20.5 degrees, the optimized modes of co-burning dust of deteriorated coal and gas are ensured by mechanical underburning of fuel particles with different contents of volatile combustible substances and the release of nitrogen oxides with combustion products. The presence of an additional air outlet nozzle contributes to the activation of combustion of the largest particles of solid fuel, separating from the dusty air stream.

The invention is illustrated by drawings, where figure 1 shows a diagram of a multi-function burner with single-row placement in the body of the main and additional gas outlet nozzles, adjacent to the under-floor of the dust-exhaust window of the additional air-outlet nozzle in horizontal section; figure 2 is a view And from the furnace to a heat-shielding casing with gas and dust-venting windows and nozzles in figure 1; figure 3 is a diagram of a multi-function burner with double-row placement in the body of the main and single-row additional gas outlet nozzles, with a piers between the hearth of the dusty air outlet and the additional air outlet nozzle in horizontal section; figure 4 is a view B from the furnace to a heat-shielding case with gas and dust-venting windows and nozzles in figure 3; figure 5 is a diagram of a multi-function burner with a multilayer housing 1 and a diagram of its installation on the wall of the combustion chamber, horizontal section.

The multi-function burner in FIGS. 1, 2 comprises a heat-shielding housing 1 with vertically slotted dust-air exhaust 2 and a main air-exhaust 3 windows, a wall 4 between them, a conditional vertical plane of symmetry 5; the dust-exhausting window 2 has an outer 6 and an inner 7 vertical walls, a ceiling 8 and a hearth 9 floors; the air outlet window 3 also has an external 10 and an internal 11 vertical walls, a ceiling 12 and a hearth 13 floors; under the dusty air outlet window 2 in the housing 1 without a wall there is an additional air outlet nozzle 14; in the housing 1 along the outer wall 10 of the main air outlet window 3 at an angle "α ₁ " to the conditional vertical plane of symmetry 5, the main gas outlet nozzles 15 are installed, arranged in one vertical row; from the side of the wall 6 of the dusty exhaust window 2 at an angle "α ₂ " to the conditional vertical plane of symmetry 5, additional gas outlet nozzles 16 are installed, also arranged in one vertical row. The axes 17 of all nozzles 15 pass through a conditional vertical plane 19, and the axes 18 of all nozzles 16 pass through a conditional vertical plane 20. Plane 19 with axes 17 of all nozzles 15 forms an angle “α ₁ ” with conditional plane 5, and plane 20 with axes 18 all nozzles 16 - angle "α ₂ ".

The multi-function burner in FIGS. 1, 2 is carried out by supplying dust and air flows to the boiler furnace through windows 2, 3 and the nozzle 14, and gas through the nozzles 15, 16. When flowing into the combustion chamber, the streams are heated to the temperature necessary for ignition, the fuel particles enter the exothermic oxidative reaction with atmospheric oxygen with the formation of high-temperature flue gases. The latter give heat to the water supplied to the boiler to generate steam. The removal of gas outlet nozzles 15, 16 beyond the dimensions of the windows 2, 3 achieves acceptable thermal conditions of the housing 1, and turning them to certain angles "α ₁ " and "α ₂ " minimizes the yield of nitrogen oxides, carbon monoxide and heat loss with chemical and mechanical unburned fuel, regardless of the design ratios of channels 2, 3 and the type of fuel burned. It is possible to burn only gas, only coal dust and co-burning gas with dust.

The burner feature in FIGS. 3, 4 is a two-tier arrangement of the main gas outlet nozzles 15 and the presence of a wall 21 between the hearth 9 of the dust-exhausting channel 2 and the additional air-outlet nozzle 14. For a fixed angle “α ₁ ” for both rows of the main gas-outlet nozzles 15, conditional passage planes 19 their axes 17 are parallel to each other.

The operation of the multi-function burner in figure 3, 4 is similar to the operation of the burner in figure 1, 2.

The housing 1 of the multi-function burner shown in FIG. 5 can be multilayer. Layer 22, facing the combustion torch, is made of heat-resistant concrete, layer 23 is made of porous poorly conductive heat foam concrete, which extinguishes the heat flow from the furnace. Perhaps the use of additional heat-absorbing materials.

The operation of the burner in FIG. 5 is similar to the operation of the burner in FIGS. 1, 2.

, а концентрация окиси углерода CO≈0%. Последнее означает, что и степень химического недожога газообразного топлива q_x≈0%. При α₁=2,5 град появляются следы СО в уходящих газах, а соответствующие потери тепла (степень) химического недожога топлива q_x≈0,05%. Как только α₁≤2,5 град, параметры CO>0%, q_x=0,5÷1,0%, то есть начинают резко скачкообразно увеличиваться; при этом значения

сохраняются. При α₁=9,5 град уровень

на ~5%, а при α₁>9,5 град параметр NO_x резко скачкообразно увеличивается, достигая 120-130% от своего минимального значения

; при этом СО≈0%; q_x≈0%. Отсюда только в диапазоне α₁=2,5-9,5 град сохраняются улучшенными все показатели сжигания газа: NO_x, СО и q_x. Все то же сохраняется и при α₂=6; 15; 20 град. При α₂=5,5 град и при α₂=20,5 град значения NO_x увеличиваются на ~5%, а при даже незначительных дальнейших отклонениях α₂<5,5 град и α₂>20,5 град параметр NO_x достигает величины

. Значения параметра "α₂" очень сильно влияют на протекание процесса совместного сжигания газа и угольной пыли. При фиксированном α₁=5,0 град и 5,5 град <α₂<20,5 град все частицы с содержанием летучих горючих веществ V^Л=10-46% имеют минимальные потери тепла с механическим недожогом топлива

и концентрацию оксидов азота в продуктах сгорания

. При α₂=5,5 град

, если V^Л≥40%;

, если V^Л=20-30%;

, если V^Л=10-20%. Как только α₂=5,0 град параметр, характеризующий качество горения "q_M" начинает резко скачкообразно увеличиваться:

, если V^Л≥40%;

, если V^Л=20-30%;

, если V^Л<20%. При этом параметры СО≈0%; q_x1≈%;

во всех вышерассмотренных случаях. Если α₂=20,5 град, то

для всех видов твердого топлива; дальнейшее даже незначительное увеличение угла наклона, например до α₂=21,0 град, приводит к резкому скачкообразному увеличению экологического показателя горения до

; значения

, CO≈0%; q_x1≈0%, то есть не меняются во всех случаях используемого топлива. При дальнейшем, даже незначительном, увеличении угла наклона, например до α₂>21,0 град, кроме того, наблюдается резкое увеличение потока тепла в направлении топливо- и воздуховыводящих окон многофункциональной горелки, что уже нежелательно с позиции термостойкости этих элементов. Таким образом, только в диапазоне α₂=5,5-20,5 град сохраняются минимальные показатели совместного сжигания газа и угольной пыли различного качества: CO≈0%; q_x1≈0%,

;

. Та же картина наблюдается, если фиксируется параметр α₁=3; 7; 9 град. Как только α₁=2,5 град; α₁=9,5 град значение NO_x1 увеличивается на ~5%; дальнейшее отклонение этого параметра до α₁=2,0 град; α₁=10,0 град приводит к резкому скачкообразному увеличению NO_x1 на 30-40%. Раздельное сжигание газа только в основных 15 или только в дополнительных 16 газовыпускных соплах ухудшает параметры горения: появляются следы сажи на стенах, в связи с чем возникает необходимость увеличивать расход воздуха. Неизбежно при этом увеличиваются потери тепла с уходящими газами, а также концентрация оксидов азота. Форма дополнительного воздуховыводящего сопла 14 и наличие установочного простенка 21 принципиально на процесс горения пыли в топке не влияют. Вместе с тем наличие самого дополнительного сопла 14 существенно способствует снижению недожога сепарирующих из пылеугольного факела крупных частиц. При испытаниях котла БКЗ-210-140Ф конструктивные параметры высоты, длины, ширины пыле- и воздуховыводящих окон 2, 3 имели фиксированные значения, также как диаметры и количество газовыпускных сопл 15, 16. Отыскание возможной связи обозначенных параметров с режимами работы топочного устройства - за границами настоящего изобретения. Дополнительный анализ термостойкости горелок показал, что при использовании установочных значений углов α₁=2,5-9,5 град; α₂=5,5-20,5 град в направлении топливовыводящих окон и сопл со стороны факела фиксируется минимальный уровень падающих лучистых потоков. Выход за пределы α₁>9,5 град; α₂>20,5 град влечет резкое скачкообразное увеличение падающих лучистых потоков в 1,5-2 раза с нарушением прочности конструкций топливовыводящих окон и сопл. Таким образом, диапазоны α₁=2,5-9,5 град; α₂=5,5-20,5 град полезны для использования не только с экономических и экологических позиций, но и с точки зрения термостойкости, продления срока службы основных технологических узлов многофункциональных горелок.The practical use of a multifunctional burner is associated with the combustion devices of boiler units of thermal power plants that burn gas and coal with various thermophysical properties. In particular, on the boiler BKZ-210-140F of the Chelyabinsk TPP-2, burners are installed on the wall of the combustion chamber in accordance with the diagram in Fig. 5. The burner housing 1 is built into the wiring of the screen tubes 24 and is attached to them by a metal sheet 25. An air duct 26 and a dust duct 27 are connected to the sheet mount 25. Nozzles 15, 16 are connected to the gas ducts 28, 29. The flow of air, dust and gas is controlled by flow regulators , in figure 5 they are not shown. A heat-shielding insulation layer 30 is applied to the screen tubes 24. During operation of the BKZ-210-140F boiler with burners in FIG. 5, a certain relationship was found between the flare parameters of gaseous and solid fuels with the angle of installation of the gas outlet nozzles α ₁ and α ₂ . The parameter "α ₁ " mainly characterizes the efficiency of the gas combustion process. So if you fix α ₂ = 10 degrees, and 2.5 degrees <α ₁ <9.5 degrees, then the values of the concentration of nitrogen oxides have minimum values

, and the concentration of carbon monoxide CO≈0%. The latter means that the degree of chemical underburning of gaseous fuel q _x ≈0%. At α ₁ = 2.5 degrees, traces of CO appear in the exhaust gases, and the corresponding heat loss (degree) of the chemical underburning of the fuel is q _x ≈ 0.05%. As soon as α ₁ ≤2.5 deg, the parameters CO> 0%, q _x = 0.5 ÷ 1.0%, that is, they begin to increase sharply in steps; with values

saved. When α ₁ = 9.5 deg level

by ~ 5%, and for α ₁ > 9.5 degrees, the parameter NO _x increases abruptly, reaching 120-130% of its minimum value

; while СО≈0%; q _x ≈0%. Hence, only in the range of α ₁ = 2.5–9.5 deg are all the indicators of gas combustion improved: NO _x , СО, and q _x . All the same holds true for α ₂ = 6; fifteen; 20 deg. With α ₂ = 5.5 degrees and with α ₂ = 20.5 degrees, the values of NO _x increase by ~ 5%, and even with slight further deviations of α ₂ <5.5 degrees and α ₂ > 20.5 degrees, the parameter NO _x reaches a value

. The values of the parameter "α ₂ " greatly affect the course of the process of co-combustion of gas and coal dust. With a fixed α ₁ = 5.0 degrees and 5.5 degrees <α ₂ <20.5 degrees, all particles with a content of volatile combustible substances V ^L = 10-46% have minimal heat loss with mechanical underburning of fuel

and the concentration of nitrogen oxides in the products of combustion

. When α ₂ = 5.5 degrees

if V ^L ≥40%;

if V ^L = 20-30%;

if V ^L = 10-20%. As soon as α ₂ = 5.0 deg, the parameter characterizing the combustion quality "q _M " begins to increase sharply in steps:

if V ^L ≥40%;

if V ^L = 20-30%;

if V ^L <20%. Moreover, the parameters СО≈0%; q _x1 ≈%;

in all the above cases. If α ₂ = 20.5 deg, then

for all types of solid fuel; a further even slight increase in the angle of inclination, for example, to α ₂ = 21.0 degrees, leads to a sharp jump-like increase in the ecological index of combustion to

; values

, CO≈0%; q _x1 ≈0%, that is, do not change in all cases of the used fuel. With a further, even insignificant, increase in the angle of inclination, for example, to α ₂ > 21.0 degrees, in addition, there is a sharp increase in the heat flux in the direction of the fuel and air outlet windows of the multi-function burner, which is already undesirable from the position of heat resistance of these elements. Thus, only in the range of α ₂ = 5.5–20.5 degrees the minimum indicators of joint combustion of gas and coal dust of various qualities are preserved: CO≈0%; q _x1 ≈0%,

;

. The same picture is observed if parameter α ₁ = 3 is fixed; 7; 9 deg. As soon as α ₁ = 2.5 deg; α ₁ = 9.5 deg; the value of NO _x1 increases by ~ 5%; further deviation of this parameter to α ₁ = 2.0 deg; α ₁ = 10.0 deg leads to a sharp spasmodic increase in NO _x1 by 30-40%. Separate gas burning only in the main 15 or only in an additional 16 gas outlet nozzles worsens the combustion parameters: traces of soot appear on the walls, and therefore there is a need to increase air flow. Inevitably, this increases the loss of heat with flue gases, as well as the concentration of nitrogen oxides. The shape of the additional air outlet nozzle 14 and the presence of the installation wall 21 fundamentally do not affect the process of burning dust in the furnace. At the same time, the presence of the additional nozzle 14 substantially contributes to reducing the underburning of large particles separating from the pulverized coal torch. When testing the boiler BKZ-210-140F, the design parameters of the height, length, width of the dust and air outlet windows 2, 3 had fixed values, as well as the diameters and number of gas outlet nozzles 15, 16. Finding a possible connection of the indicated parameters with the operating modes of the combustion device the boundaries of the present invention. An additional analysis of the heat resistance of the burners showed that when using the set values of the angles α ₁ = 2.5-9.5 degrees; α ₂ = 5.5-20.5 degrees in the direction of the fuel outlet windows and nozzles from the side of the torch, the minimum level of incident radiant fluxes is fixed. Going beyond α ₁ > 9.5 deg; α ₂ > 20.5 deg entails a sharp jump-like increase in incident radiant fluxes by 1.5–2 times, with a violation of the structural strength of the fuel outlet windows and nozzles. Thus, the ranges α ₁ = 2.5 to 9.5 degrees; α ₂ = 5.5–20.5 degrees are useful not only from an economic and environmental point of view, but also from the point of view of heat resistance, extending the service life of the main technological units of multi-function burners.

Claims (1)

A multifunctional burner containing a heat-shielding case with a vertically slotted separated wall and a conditional vertical plane of symmetry of the dust-exhaust and main air-outlet windows having external and internal vertical walls, ceiling and hearth ceilings, an additional air-outlet nozzle and outside the window dimensions placed in the housing under the dust-exhaust window, arranged in vertical rows and installed in the housing at an angle to the conventional vertical plane of symmetry th rods along the outer wall of the main air outlet window main gas outlet nozzles, as well as additional gas outlet nozzles, characterized in that the installation angle of the main gas outlet nozzles is 2.5 to 9.5 degrees, and the additional gas outlet nozzles are also arranged in vertical rows, outside the window dimensions but installed along the outer wall of the dusty air outlet window at an angle to the conditional vertical plane of symmetry of the burner, equal to 5.5-20.5 degrees.

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