JPH02106608A - Radiant gas burner - Google Patents

Abstract

PURPOSE:To reduce thermal NOX through slow combustion by forming a flat flame inside the furnace by ejecting from ejection holes a fuel-air premix produced by mixing raw gas and primary air in the main body of a gas burner and on the other hand by ejecting into the furnace in a manner of diffusion from ejection holes the raw gas flowing through a communicating pipe and a gas chamber. CONSTITUTION:When raw gas A is blown into an outer end opening 5a from an ejection hole 13 of a primary gas nozzle 12, primary air B is drawn in by the ejector action at a venturi tube section 5. The raw gas A and the primary air B are preliminarily mixed to form a fuel-air premix C, which is ejected into the furnace 15 through premix ejection holes 11A, 11B, 11C in a secondary gas nozzle 4 to form a stabilized flat flame. With the primary air B drawn in amounting to less than the quantity required for the combustion, the combustion is thinly supplied with fuel so that the formation of thermal NOX is suppressed. The raw gas A flowing through a communicating pipe 14 from the primary gas nozzle 12 is sent into a gas chamber 8 under pressure and from hence ejected into the furnace 15 through unmixed gas ejection holes 10. The raw gas A is ejected in a manner of diffusion without being premixed with air and made to burn slowly. The combustion is slow and stabilized, free from peaks in temperature, and results in the reduction of thermal NOX.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a radiant gas burner used in ethylene cracking furnaces, ethylene dichloride cracking furnaces, and the like.

Conventional technology The gas burners used in ethylene cracking furnaces and ethylene dichloride cracking furnaces have traditionally been used for the purpose of uniformly heating the heating tubes.
A radiant gas burner that forms a flat flame is used. These gas burners are generally of the natural draft type and are constructed as premixed gas burners using ejector action.

That is, as shown in FIGS. 3 and 4, the gas burner main body 21 is disposed inside and outside the furnace through a through hole 23 formed in the furnace wall 22, and has a secondary gas nozzle portion 25 protruding into the furnace interior 24. , a venturi tube portion 27 protruding outside the furnace 26
It consists of The secondary gas nozzle part 25 has a closing part 25a at its tip, and in the vicinity of the closing part 25a, there are multiple stages (4Vi> jet ports 26A in the figure) whose jetting direction is directed toward the burner tile (furnace wall inner surface) 22a. 26B.

26C and 26D are formed at equal intervals in the circumferential direction. A primary gas nozzle 28 attached to the free end of a gas supply pipe (not shown) is arranged opposite to the opening 27a of the venturi pipe section 27 outside the furnace 26.

According to such a conventional configuration, the raw gas G is ejected from the primary gas nozzle 28 toward the opening 27a, thereby causing the Venturi pipe portion 27 to have an ejector action and sucking the primary air H from the outside. and primary air H are mixed during flow to form a premixture (2). Then, the premixture I is ejected from the jet ports 26A to 26D, forms a flat flame, and is burned along the burner tile 22a, giving heat to the heated tube (not shown) with radiant heat from the flame surface. There is. At this time, secondary air J is supplied through the through hole 23.

Problems to be Solved by the Invention According to the conventional type as described above, the secondary gas nozzle part 25
At the ignition point of It becomes. In addition, since the premixture ■ of the raw gas G and the primary air H is supplied and combusted, this premixture ■ mixes well with the secondary air J, and combustion occurs quickly and combustion is not completed. It burns quickly and stably. However, on the other hand, there is a problem that thermal NOx is easily generated.

In recent years, both domestically and internationally, NOx value regulations have begun to be tightened not only for new furnaces but also for existing furnaces, and countermeasures for existing burners have become necessary, so it is important that NOx is easily generated. That's a problem.

The purpose of the present invention is to be able to equip not only new furnaces but also existing furnaces with a slight modification, and to forcibly increase the aforementioned bias ratio without reducing combustion efficiency. The object of the present invention is to provide a radiant gas burner that can significantly reduce NOx.

Means for Solving the Problems In order to achieve the above object, the radiant gas burner of the present invention is a radiant gas burner that is disposed inside and outside the furnace through a through hole formed in the furnace wall, and has a gas burner main body with a closed tip. A plurality of ejection ports are formed in the longitudinal direction near the tip of the gas burner body, and a gas chamber communicating with the most advanced ejection port is formed in the gas burner body, and a primary gas nozzle is arranged opposite to the outer end opening of the gas burner body. It is arranged in an elliptical shape so that primary air is sucked into the gas burner body by an ejector action caused by blowing raw gas, and a connecting pipe branched from the primary gas nozzle side is communicated with the gas chamber through the gas burner body. .

According to the configuration of the present invention, the premixture generated by mixing raw gas and primary air within the gas burner body is ejected from the jet port into the furnace, forms a stable flat flame, and burns. . At this time, since the amount of primary air is smaller than the required amount of air, the premixture achieves fuel lean combustion while ensuring a stable flame, and the generation of thermal NOx is suppressed. On the other hand, the raw gas flowing through the gas chamber from the connecting pipe is diffused and ejected into the furnace from the nozzle and is burned, but at this time, the raw gas does not carry air with it, and the vicinity of the gas spout is filled with air. Due to the shortage, a combustion delay occurs, and the gas becomes over-rich, causing slow combustion and reducing thermal NOx.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 and 2.

Reference numeral 1 designates a gas burner main body, which is disposed inside and outside the furnace through a through hole 3 formed in a furnace wall 2, and includes a secondary gas nozzle portion 4 projecting into the furnace interior 15 and a Venturi tube portion 5 projecting outside the furnace 16. , are integrated by a screw connection 6 or the like. The tip (inner end) of the secondary gas nozzle section 4 is a closing section 4a, and a partition body 7 is provided at a position slightly outward from the closing section 4a to form a gas chamber 8 at the tip. The outer portion is formed into a premix air flow path 9.

Note that the closing portion 4a is formed in a conical shape with its center protruding into the gas chamber 8. In the secondary gas nozzle section 4, a plurality of stages (four stages in the figure) of ejection ports are formed near the closing section 4a. That is, the most advanced first-stage ejection port is a raw gas ejection port 10 whose ejection direction is aligned with the burner tile (furnace wall inner surface > 2a), and is formed equally spaced in the circumferential direction, and It communicates with the gas chamber 8.The remaining second to fourth stage jet ports have their jet directions aligned with the bar.
The premixture outlet 11A is directed toward the natile 2a.

11B and 11C, these are also formed in equally spaced chambers in the circumferential direction, and communicate with the premixture flow path 9.

The primary gas nozzle 12, which is disposed opposite the outer end opening 5a of the Venturi pipe section 5, has a plurality of ejection ports 13 formed at its tip in the circumferential direction. and spout 13
By attaching the base end to the center of the group, the primary gas nozzle 12
A connecting pipe 14 branched from the gas burner main body 1 is communicated with the gas chamber 8 through the gas burner main body 1.

In the above-mentioned radiant gas burner, the raw gas A is
When the primary air B is blown in, the ejector action of the venturi tube section 5 sucks the primary air B.

The raw gas A and the primary air B are premixed and flow through the channel 9 as a premixture C, and then are ejected into the furnace 15 from the premixture jet ports 11A, 11B, and 11C of the secondary gas nozzle section 4. , it burns by forming a stable flat flame. At this time, due to the ejector action, a smaller amount of primary air B is sucked in than the amount of air required for combustion, and therefore, the premixture C becomes fuel-lean combustion while ensuring a stable flame, resulting in thermal NO.
Generation of x is suppressed. During such combustion, secondary air is supplied through the through hole 3. Also, the primary gas nozzle 1
The raw gas A of No. 2 is forced into the gas chamber 8 through the connecting pipe 14, and is then jetted into the furnace interior 15 from the raw gas spout 10.

At this time, the raw gas A is not premixed with air and is combusted as a diffused jet. However, due to the lack of air near the gas jetting part, a combustion delay occurs and the gas becomes over-rich. It burns slowly along the gas flow of C. In this way, diffusion combustion is slow and stable combustion, and no temperature peak occurs, so it also reduces thermal NOx.

Distribution (%) of raw gas A from the primary gas nozzle 12 between the first stage gas amount to the flow path 9 side and the second stage gas amount to the gas chamber 8
1st stage: 2nd stage = 50-60: 50-40. When this range is exceeded, the following phenomenon occurs.

O If the first stage gas amount is 50% or less (the second stage gas amount is 50% or more), combustion stability will be significantly lacking.

If the O first stage gas amount is set to 60% or more (the second stage gas amount is set to 40% or less), the NOxIIJ effect will be significantly inferior.

The gas burner main body 1 described above can be installed in all types of furnaces by replacing the secondary gas nozzle section 4, for example.

Effects of the Invention According to the present invention having the above configuration, a premixture obtained by mixing raw gas and primary air within the gas burner body is ejected from the jet port into the furnace, and is combusted by forming a stable flat flame. At that time, the amount of primary air is smaller than the required amount of air, so the premixture can ensure a stable flame while achieving fuel-lean combustion, which can suppress the generation of thermal NOx. The raw gas that flows through the gas chamber from the connecting pipe and is diffused and ejected into the furnace from the ejection port is not accompanied by air, and there is a lack of air near the gas ejection part, so a combustion delay occurs and the gas The mixture becomes too concentrated, resulting in slow combustion, and thermal NOx can still be reduced. As described above, according to the present invention, combustion is a combination of fuel-lean combustion and fuel-rich diffusion combustion, and the bias ratio is larger than that of a normal premix burner, which improves the economic efficiency of this premix burner. , it is possible to significantly reduce NO while maximizing the advantage of combustion stability. The radiant gas burner of the present invention can be installed not only in new furnaces but also in existing furnaces with slight modification.

[Brief explanation of drawings]

Figures 1 and 2 show one embodiment of the present invention, with Figure 1 being a longitudinal sectional view, Figure 2 being a partial longitudinal sectional view of the raw gas supply section, and Figure 3 being a longitudinal sectional view of a part of the raw gas supply section.
The figure is a longitudinal sectional view of the conventional example, and FIG. 4 is an enlarged view of the main part in FIG. 3. DESCRIPTION OF SYMBOLS 1... Gas burner main body, 2... Furnace wall, 3... Through hole, 4... Secondary gas nozzle part, 4a... Closure part, 5
... Venturi tube section, 5a... Outer end opening, 7.
... Partition body, 8... Gas chamber, 9... Premixed gas flow path, 10... Raw gas outlet, 11A, 11B, 11
C... Premixture jet port, 12... Primary gas nozzle,
13...Blowout port, 14...Connecting pipe, A...Raw gas, B...Primary air, C...Premixture. Agent Yoshihiro Moriki

Claims (1)

[Claims] 1. A radiant gas burner that is installed both inside and outside the furnace through a through hole formed in the furnace wall, and has multiple ejection ports formed in the longitudinal direction near the tip of the gas burner body with the tip closed, and A gas chamber communicating with the jet nozzle at the tip is formed in the gas burner body, and a primary gas nozzle facing the outer end opening of the gas burner body is arranged to direct primary air into the gas burner body by an ejector action caused by blowing raw gas. 1. A radiant gas burner, characterized in that a connecting pipe branched from the primary gas nozzle is communicated with the gas chamber through a gas burner main body.