RU2079047C1 - Boiler furnace - Google Patents

Abstract

FIELD: thermal power stations burning gas and dust of solid fuel. SUBSTANCE: furnace contains vertical tetrahedral prismatic combustion chamber and main burners mounted on its two opposite walls in at least two horizontal rows; main burners are fitted with nozzles for introduction of air, aeromixture and fuel gas oriented tangentially relative to reference circle in center of chamber; circles of fuel nozzles are inside circle of air nozzles; additional burners are fitted on walls free from main burners. Additional burners are mounted in pairs at level of lower horizontal row of main burners symmetrically relative to horizontal axis of combustion chamber at angle of turn between combustion chamber and plane of exhaust section of γ deg and pitch of C-(0.13-0.75)B, where B is width of walls where additional burners are fitted, m. EFFECT: enhanced efficiency. 4 dwg

Description

 The invention relates to energy and can be used in boilers of thermal power plants that burn gas and dust of solid fuel.

A boiler furnace is known that contains a vertical prismatic combustion chamber and dust and gas burners installed in its corners, equipped with nozzles for introducing air, aerosolum and fuel gas into the combustion chamber, which are installed tangentially to the conditional circles in the center of the chamber, and the circumference of the fuel nozzles inside the air circumference (a. c. USSR 1695036, from 01.09.89 M. cl. F 23 C 1/12; published in B.I. N 44 from 1991)
The drawback of the furnace is a torch breakage during the combustion of coal dust with unstable thermal characteristics (variable humidity, ash content, content of volatile combustible substances in the coal supplied to the boiler). Moreover, the breakdown of the pulverized coal torch occurs when burning as one coal, and together with gas.

 A boiler furnace is also known, containing a vertical tetrahedral prismatic combustion chamber and main burners installed on two opposite walls in at least two horizontal rows, equipped with nozzles for introducing air, air mixture and fuel gas, oriented tangentially to conditional circles in the center of the chamber, and circles fuel nozzles inside the air circumference; in addition, on the walls with the main burners and free of them, additional burners are installed for kindling and lighting the main torch (Osintsev V.V. et al. Transfer of the BKZ-160 boiler to the technology of step-by-step fuel combustion. "Electric stations", 1993, No. 3 p. 25-29). By introducing a highly reactive backlight fuel (gas or fuel oil), continuous burning of the main pulverized coal fuel with degraded variable thermotechnical characteristics — moisture, ash, and content of combustible volatile substances — is achieved. This firebox is taken as a prototype of the invention.

 The disadvantage of this furnace is the significant consumption of backlight fuel through additional burners to maintain the main flame, increased underburning of the injected coal dust, large losses with gases removed from the boiler (underutilization of the heat of the injected fuel), and an increase in the concentration of nitrogen oxides in the exhaust products of combustion.

 The objective of the device is to reduce the consumption of backlight fuel, underburning of the main fuel, heat loss with flue gases and the concentration of nitrogen oxides in the exhaust products of combustion, that is, to eliminate the disadvantage of the prototype.

To accomplish this task, in the boiler furnace containing a vertical tetrahedral prismatic combustion chamber and installed on its two opposite walls in at least two horizontal rows, the main burners are equipped with nozzles for introducing air, air mixtures and fuel gas, oriented tangentially to the conditional circles in the center of the chamber moreover, the circumference of the nozzles inside the circumference of the air, as well as additional burners placed on the walls not occupied by the main burners, additional burners are installed in pairs at the level of the lower horizontal row of the main burners symmetrically with respect to the horizontal axis of the combustion chamber with a rotation angle between it and the plane of the straight section γ (75 105) ^o and step C (0.15 0.75) B, where B is the width of the walls with additional burners, m

при сжигании как одной угольной пыли с резкопеременными влажностью, зольностью, содержанием горючих летучих включений, так и угольной пыли вместе с топливным газом, а также минимальную концентрацию оксидов азота в отводимых продуктах сгорания

минимальные относительные тепловые потери тепла основного топлива с уходящими газами

и механическим недожогом

. Здесь и ниже: g g/g прот.

степень подсветки текущая;

степень подсветки по прототипу; B_p, B_p расход топлива на подсветку, расход угля, кг/с; Q $\genfrac{}{}{0ex}{}{\text{hg}}{\text{н}}$ , Q $\genfrac{}{}{0ex}{}{\text{he}}{\text{н}}$ теплота сгорания подсветочного топлива и угля,

;

NO_x, NO_x прот. концентрация оксидов азота текущая и по прототипу,

;

g₂, g₂ прот. потери (недоиспользование) тепла вводимого топлива с отводимыми в атмосферу газами, текущие значения и по прототипу,

; g₄, g_4прот потери тепла вводимого топлива с недожогом угля, текущие и по прототипу.The identified placement of additional burners relative to the main dust and gas burners on the walls of the combustion chamber ensures a minimum relative heat consumption of the backlight fuel

when burning one coal dust with very variable humidity, ash content, content of combustible volatile inclusions, and coal dust together with fuel gas, as well as the minimum concentration of nitrogen oxides in the exhaust products of combustion

minimum relative heat loss of heat of the main fuel with flue gases

and mechanical burnout

. Here and below: gg / g prot.

current backlight level;

the degree of illumination of the prototype; B _p , B _p fuel consumption for backlighting, coal consumption, kg / s; Q $\genfrac{}{}{0ex}{}{\text{hg}}{\text{n}}$ , Q $\genfrac{}{}{0ex}{}{\text{he}}{\text{n}}$ calorific value of backlight fuel and coal,

;

NO _x , NO _x prot. the concentration of nitrogen oxides current and prototype,

;

g ₂ , g ₂ prot. loss (underutilization) of heat of introduced fuel with gases discharged into the atmosphere, current values and according to the prototype,

; g ₄ , g _4prot heat loss of the injected fuel with the burning of coal, current and prototype.

. При незначительных отклонениях γ и C в большую или меньшую сторону параметры

сохраняют свои значения. При γ 75^o; g 105^o; C=0,15•B; C=0,75•B параметры

;

;

;

незначительно ухудшались. Как только γ<75 град; γ>105 град; C < 0,15 B; C > 0,75 B параметры

, то есть резко скачкообразно достигают ухудшенных значений, соответствующих прототипу. Аналогичные результаты получаются и при одновременной подаче через основные горелки угольной пыли и топливного газа. Положительные результаты получаются при конструктивном оформлении топки как по варианту 1 (фиг. 1, 2), так и варианту 2 (фиг. 3, 4).The ranges γ (75 105) ^o and C (0.15 0.75) B are advantageous from the standpoint of obtaining a positive effect. When testing the furnaces, it was revealed that, burning only coal with unstable humidity 13 26% ash content 18 40% hot volatile inclusions 25 32% and setting additional burners at g 90 ^o and C 0.245 B, the parameters

. With slight deviations of γ and C up or down, the parameters

retain their values. At γ 75 ^o ; g 105 ^o ; C = 0.15 • B; C = 0.75 • B parameters

;

;

;

slightly worsened. As soon as γ <75 deg; γ> 105 deg; C <0.15 B; C> 0.75 B parameters

, that is, sharply abruptly reach degraded values corresponding to the prototype. Similar results are obtained with the simultaneous supply of coal dust and fuel gas through the main burners. Positive results are obtained with the design of the furnace as in option 1 (Fig. 1, 2), and option 2 (Fig. 3, 4).

 In FIG. 1 shows a diagram of a boiler furnace (option 1) with a vertical tetrahedral prismatic combustion chamber; in FIG. 2, section AA in FIG. one; in FIG. 3 diagram of the furnace (option 2); in FIG. 4 a section BB in FIG. 3.

The boiler furnace contains a vertical prismatic combustion chamber 1 with walls 2, 3; on the walls 2 there are placed the main burners 4, equipped with nozzles 5, 6, 7 for introducing coal dust, fuel gas and air, respectively; the axis 8 of the fuel nozzles 5, 6 are directed tangentially to the conditional circle 9 to the center of the furnace, and the axes 10 of the air nozzles 7 are tangent to the conditional circle 11, the walls of the chamber 1 are shielded by pipes 12 with a heated steam-water medium; the center of the circles 9, 11 on the vertical axis 13 of the chamber 1; additional burners 14 are installed on the walls 3, the pitch of which is C (0.15 0.75) B; angles between the horizontal axis 15 and the plane 16 of the direct exhaust section γ (75 105) ^o .

The operation of the boiler furnace is carried out by entering through the burner 2 streams of dust, gas and air. Dust is supplied through nozzles 5, gas through nozzles 6, and air through nozzles 7. Flowing jets of dust and gas are directed tangentially to circle 9, and air flows to circle 11. Fuel and air flows enter under the influence of diffusion-turbulent mixing with a hot combustion medium in a chemical reaction with the release of heat, forming the main torch, which gives off the released heat to the screens 12. The resulting combustion products move towards the exit window 17 and through the duct system with heating surfaces, gas treatment plants and movuyu pipe is discharged into the atmosphere. Through additional burners 14, air and highly reactive fuel (natural gas, fuel oil) are supplied to combustion chamber 1, during the combustion of which additional heat is released, supporting combustion in the main flame during sharp fluctuations in humidity, ash, and the content of combustible volatile substances in the pulverized coal entering through the burners 2 fuel. The geometric ratios g (75 105) ^o and C (0.15 0.75) B provide the minimum values of the consumption of backlight fuel, the concentration of nitrogen oxides in the exhaust products of combustion, heat loss with flue gases and the underburning of solid fuel.

Claims (1)

The boiler furnace, containing a vertical tetrahedral prismatic combustion chamber and installed on its two opposite walls in at least two horizontal rows, is the main burner equipped with nozzles for introducing air, air mixture and fuel gas, oriented tangentially to the conditional circles in the center of the chamber, and the circles of the fuel nozzles located inside the circumference of the air, as well as additional burners placed on the walls not occupied by the main burners, characterized in that the additional burners ki are installed in pairs at the level of the lower horizontal row of the main burners symmetrically with respect to the horizontal axis of the combustion chamber with a rotation angle between it and the plane of the exhaust straight section equal to 75 105 ^o and a step of 0.15 0.75 of the width of the walls with additional burners, m

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