JPS58190605A - Three-stage combustion in restricting nox for performing desulfurization simultaneously - Google Patents

Abstract

PURPOSE:To improve an efficiency of desulfurization of the discharging combustion gas by a method wherein a furnace is divided into a primary combustion chamber and a second combustion chamber and then a desulfurization agent is applied in the primary combustion chamber. CONSTITUTION:A primary combustion chamber 22 is kept at a high temperature higher than that of fluidizing point of the ash, a primary fuel 25 is burned to make the ash to its molten condition and then discharged from the outlet port 38. Then, the primary discharging combustion gas from the primary combustion chamber 22 is supplied to the secondary combustion chamber 23 through the duct 24, excessive secondary fuel 27 is supplied from the secondary fuel nozzle 28 and burned while the secondary combustion region 34 being held in the reducing atmosphere and at the same time alkaline substance is supplied from the desulfurization agent supplying nozzle 30 as desulfurization agent 29 so as to desulfurize the gas. Then, the secondary discharging combustion gas is burned at the third combustion region 35 by supplying the secondary air 31 from the secondary air nozzle 32. The non-combustion material contained in the gas is completely burned and oxidized and thereafter discharged to the outside of the furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-stage reef firing method for NOx suppression performed during atX removal.

Conventionally, one method of desulfurizing combustion exhaust gas from fuel with conflicting ash content is to supply alkali (often in powder form) directly into the furnace.
There is a method of absorbing and removing it as sulfate or bisulfate. However, with this method, if the humidity inside the furnace is high, CaO+502+1/202-"CaSO4...=
(1) Na 20+ SO2+ 1/202-Na 2
504 °"""" Reactions such as (2) are difficult to occur, and as is clear from the relationship between the furnace temperature and desulfurization rate shown in Figure 1, pQ decreases at temperatures above 1 (XX) °C.
There was a problem that the sulfur rate decreased. On the other hand, in the reducing atmosphere, CaO+H2S-Ca5+H20・---------・(
3) Published by Nu204H25 (a2S+H20...
...(4) NaO+SO+3C-NaS+3CO
The main reaction is the reaction that creates sulfides such as (6) 2 2 2.

The sulfide produced by this reaction is stable at high temperatures. Therefore, a method has been considered in which the primary combustion zone is subjected to reductive combustion using the air-flow two-stage combustion method, which is known as one of the NOx suppression combustion methods, and a reducing agent is supplied to this secondary combustion zone.

Figure 3 #'i shows a furnace using a method that combines the air two-stage smoking method with the in-furnace removal method, and shows the combustion
A fuel nozzle (2) for ejecting fuel (1) is provided, and a secondary air nozzle (4) for ejecting secondary air (3) is provided near the upper part of the fuel nozzle (2), and a secondary air nozzle (4) for ejecting secondary air (3) is provided near the upper part of the fuel nozzle (2), and the fuel nozzle (4) is provided near the upper part of the fuel nozzle (2) for ejecting fuel (1). A supply nozzle (6) for the desulfurizing agent (5) is provided at a position opposite to the nozzle (2). (7) is 1 empty each to fuel nozzle (2) and secondary air nozzle (4)! (8) is a wind box that introduces secondary air (1). With such a configuration, the primary combustion a! The fuel (1) is reductively combusted in R (9), and an alkali is supplied as a K desulfurizing agent (5) to the primary combustion area (9) to burn it, and the combustion exhaust gas of the primary combustion 11*(9) is It is then combusted in a secondary combustion chamber. However, with this method, most of the sulfides generated in the primary combustion zone (9) are removed from the secondary combustion zone (9), where an excessive amount of secondary air (3) is supplied and unburned matter is completely combusted. 2), the oxidized and captured S is converted into CaS+3/202-CaO+SO2...
・・・・・・・・・(6) NaS+3/202-NaO+S
The conventional desulfurization method is used to reduce the amount of O3 released by the O reaction, such as (7), in the original atmosphere of -flame combustion, and with a high I content above the pour point of the ash! It is possible to conceive of a method of preserving iK and removing the generated sulfide and ash from the combustion chamber in a molten state.

The two-stage air combustion method for JI41mFi is equipped with an in-furnace deflow method and a desulfurization agent supply nozzle (to) that spouts out an alkali as a desulfurization agent (c), and a secondary combustion chamber (2).
) K is the secondary air nozzle (to) that blows out secondary air (b)
is provided. (to) is a wind box that introduces the fuel nozzle <nK primary air. With such a configuration, one fire and smoke combustion chamber atb is maintained at a high temperature higher than the pour point of ash to burn the fuel, and an alkali (2
) and bake #a. As a result, the ash and sulfides are molten and taken out from the JIX from the molten material outlet (2) provided at the bottom of the primary combustion chamber (b), while the primary combustion in the primary combustion chamber (2) is carried out. The exhaust gas is supplied to a secondary combustion chamber (6), and in the secondary combustion chamber (6), secondary air M is supplied for secondary combustion. However, with this method, the main component of general ttC ash is silicic acid, and most of the alkali α1 supplied reacts with this silicic acid to form complex silicate compounds, resulting in less desulfurization effect. )is.

The present invention aims to solve such problems, and in a three-stage combustion method in which fuel and air are separately supplied, the furnace is divided into at least a primary combustion chamber and a secondary combustion chamber,
1 by maintaining the primary combustion chamber at a high temperature above the pour point of the ash.
In the secondary combustion chamber, half a dozen primary fuels are supplied to the secondary combustion chamber, and in the secondary combustion chamber, excess fllJ of secondary fuel is supplied to burn while maintaining the secondary combustion area in a reducing atmosphere and desulfurization. This system is characterized by supplying a chemical agent to perform desulfurization, and supplying secondary air from the flow to perform tertiary combustion to completely burn and oxidize the unburned content contained in the secondary combustion exhaust gas. By providing a now-suppressed three-stage combustion method that simultaneously performs desulfurization and desulfurization, all of these objectives can be achieved. The method of the present invention will be explained in detail based on the drawings showing one example and one example. Fig. 5 shows a secondary furnace using the VC assembly method of the present invention, the furnace is divided into a primary combustion chamber and a secondary combustion chamber, and a duct connected to the primary combustion chamber is 2
Next f! ! & It is connected so as to communicate with the center of the i' part of the grilling chamber. The upper part of the primary combustion chamber is equipped with a fuel (2) t7 jetting fuel nozzle, and the secondary combustion chamber is equipped with a secondary combustion chamber at its lower part. A secondary combustion nozzle that spouts +■
A desulfurizing agent supply nozzle for injecting the desulfurizing agent CA1 is provided near the top of the secondary fuel nozzle, and a desulfurizing agent supply nozzle for injecting the desulfurizing agent CA1 is further provided at a position above the 111th desulfurizing agent supply nozzle group in the upper part of the secondary combustion chamber. A Z-order air nozzle ~Q that blows out 6M of secondary air is provided. Therefore, the primary combustion force (2)
A primary combustion area (T) is formed in which combustion is performed by the primary fuel nozzle, and a secondary combustion area (T) is formed in the lower part of the secondary combustion chamber to perform combustion by the secondary fuel nozzle. , a 3/>C combustion zone (to) is formed in which combustion is carried out by the secondary combustion chamber 2 (Fi secondary air nozzle at the top). This becomes the #i tertiary combustion chamber (towards) the upper part of the second fire and smoke combustion chamber. 67) 1, the fuel nozzle (e), K primary air (b)
The wind box that introduces the wind box (to) is installed at the [end] of the fire and smoke chamber @f? :, molten ash removal 1]-ζ'.

The operation of this configuration will be described next. First, 1 fire and smoke combustion chamber 4 is held at a high temperature above the pour point of the ash, and 1 fire and smoke rod c18 is burned, thereby turning the sky into @job status [7τmelt to melting outlet (to) It bursts out. This molten ash slag contains most of the dust contained in the primary combustion exhaust gas. At this time, if the primary air (b) is supplied to the primary fuel nozzle for 1 t' in excess of the theoretical air amount for fuel 4, the first fire and smoke area will be oxidized and the heat absorption pipes will be corroded. can be avoided. Next, it is supplied to the secondary combustion chamber (2) via the primary combustion chamber (2)'s 1 fire smoke incineration 4 + gas duct, and in the secondary combustion chamber (2), the (to the secondary m-fuel nozzle), and burns while exposing the secondary combustion zone (to) to the main atmosphere. At this time, the desulfurizing agent is
As a result, alkali is supplied and desulfurization is carried out. Then, the primary combustion exhaust gas has already melted most of the dust contained in the primary combustion chamber (2) and removed by contacting with the ash, so the supplied alkali is removed by the silicic acid in the ash. It becomes effective with a little amount of KIIC consumed by! Perform Q-sulfur. Note that when a fuel with a low ash content is used as the secondary fuel (2), the consumption of the desulfurizing agent 9I4 is further reduced by the silicic acid in the ash, so that a greater desulfurizing effect can be achieved. After drying, the secondary combustion exhaust gas is tertiary-combusted by supplying secondary air from the secondary air nozzle ■ at 3-fire combustion V, (to), and the unburned content contained therein is completely combusted. , after being oxidized, it is discharged outside the furnace.

＠＠The figure shows another embodiment of the method according to the present invention, in which the structure of the secondary combustion chamber of the furnace shown in FIG. 5 is used. The secondary combustion chamber has a duct connected to the primary combustion chamber (2) connected to the side of the F end so as to form blood, and a sulfide duct connected to the F end of the secondary combustion chamber. An outlet is provided. The other configurations are the same as in the previous embodiment.

With such a configuration, most of the old dust in the first fire and smoke combustion chamber is removed by contacting with the molten ash and the first fire and smoke #1 exhaust gas) L is transferred to the secondary combustion chamber (c). supply to
In the secondary combustion chamber, the secondary fuel (b) is combusted while maintaining the temperature of the ash at the pour point of the ash. Also, at this time, an alkali is supplied as a cursing agent 4 from the supply nozzle (2). In contrast to alkali and sulfur compounds, a mixture of mourning sulfides and a small amount of ash is produced and collected from the sulfide removal row, while the secondary combustion exhaust gas is produced in the tertiary combustion zone (toward). Secondary air is supplied from the secondary air nozzle (2) for tertiary combustion, and the unburned matter contained in the instep is completely burned and oxidized.
C discharge. The movement of the exhaust gas during these secondary and tertiary combustions rotates and rises as shown by the arrow in the 6th wJ. As a result, as mentioned in the conventional example (
(1) formula and i(π) formula O reversion I6 will be prevented. In addition to melting and removing the sulfide, the sulfide can be generated by other means such as, for example, injecting a collision plate into the secondary combustion chamber (2) or a filler.

In order to increase the desulfurization rate, it is more preferable to collect compounds and prevent them from flowing into the tertiary combustion zone. and fuel Fi can be supplied simultaneously.

Figure 2 shows the difference in the desulfurization rate between the conventional method and the method of the present invention. It can be seen that by combining the in-furnace deflow method and the ash melt recovery method, it is possible to further increase the desulfurization rate compared to Tomokata.

As described above, according to the method of the present invention, the desulfurization rate does not decrease even when the temperature inside the furnace is high, and since the desulfurization agent is not supplied to the large roasting chamber, silicic acid and the desulfurization agent, which are the main components of the ash, are removed. This method does not cause the reaction to produce complex silicate compounds that reduce the desulfurization effect, and the desulfurization rate of combustion exhaust gas can be lowered compared to conventional methods.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the temperature inside the furnace and the desulfurization rate in the method of desulfurization by directly supplying alkali into the furnace, and Figure 2 shows the method according to the present invention and various conventional methods (equivalent ratio Fig. 3 is a longitudinal cross-sectional view of a furnace based on the circle method, which combines the conventional air two-stage combustion method with the in-furnace de-sulfurization method, and Fig. 4 shows the conventional air two-stage combustion method. The longitudinal 11r diagram of a furnace based on a method combining the stage combustion method, in-furnace desulfurization method and Nu melting method, @Figure 5 and Figure 6 show one embodiment of the present invention, and each is related to the method of the present invention. Furnace outline kl
FIG. Agent Yoshihiro Morimoto
Teie q 1 Uma part 58-190605 (4) Fig. 1 Furnace temperature (・C) (%) *υchi Fig. 3 Fig. 4 Fig. 3 Fig. 5 Fig. 6 (a) (b) Procedure amendment Calligraphy (Juri June 1981/〆U To the Commissioner of the Patent Office■, Indication of the incident Showa 57 Poem No. 71977
Ij2, invention? Three-stage combustion method for NOx suppression with simultaneous first-order desulfurization 3, relationship with the amended case Name of patent applicant (511) Hitachi Zosen Corporation 4, Agent Address: SSO 1-6, Tachiuribori, Nishi-ku, Osaka No. 17 Amano Building Telephone Osaka 06 (532) 4025 (Main)
Name (6808) Yoshihiro Moto 5,
Date (shipment date) Showa year Month Day 6 Number of inventions increased by amendment 7, subject of amendment ■ Kusunoki (1) Detailed explanation of the invention in the specification (1) Page 2, line 20, "Reducing agent" stop. Correct 6 "Desulfurizing agent". (2) In the 7th line of page 3, correct "opposite" to "opposite".

Claims (1)

[Claims] 1. In the three-stage combustion method in which fuel and air are supplied separately, the furnace is divided into at least a primary combustion chamber and a secondary combustion chamber, and the primary combustion chamber is maintained at a high temperature higher than the pour point of the ash. The primary fuel is combusted in the primary combustion chamber, whereby the ash is taken out from the primary combustion chamber in a molten state, and then (the primary combustion exhaust gas from the primary combustion chamber is supplied to the secondary combustion chamber). In the secondary combustion chamber, excess secondary fuel is supplied to burn the secondary combustion area while maintaining it in a reducing atmosphere, and a desulfurizing agent is supplied to perform desulfurization, and after this, secondary air is removed from its wake. A NOx suppression three-stage combustion method that simultaneously performs a1 removal, which is characterized by supplying and performing tertiary combustion to completely burn and oxidize unburned components contained in secondary combustion exhaust gas.