FR2530318A1 - METHOD FOR BURNING LOW CALORIFIC GAS AND BURNER FOR SUCH GAS - Google Patents

Abstract

THE BURNER FOR BURNING A GAS WITH LOW CALORIFIC POWER IS CHARACTERIZED IN THAT, FROM THE CENTER OF THE BURNER, MOVING TOWARDS THE EXTERIOR TO ITS PERIPHERY, SUCCESSIVELY AN OPENING OF AIR INJECTION 2 FOR THE FLAME IS FOUND PILOT, A LOW CALORIFIC GAS INJECTION OPENING 3A FOR THE PILOT FLAME, A LOW CALORIFIC GAS INJECTION OPENING 4 FOR THE MAIN COMBUSTION AND A MAIN AIR INJECTION OPENING 5 FOR THE COMBUSTION.

Description

Method for burning a gas with low calorific value

and burner for, such a gas.

  The present invention relates to a method for burning a gas with low calorific value and a burner for burning such a gas; it relates more particularly to a process for burning a gas with low calorific value, such as a blast furnace gas, under a high combustion load

  and to obtain a stable flame over a wide range of con-

  operating editions, and a burner to obtain this

  sufficient combustion of a gas with low calorific value.

  Because a low calorific gas, such as a blast furnace gas, burns poorly, it has hitherto been found difficult to use such a gas when combustion under high load is necessary and that, in addition, it is required that the flames be stable over a wide range of operating conditions, as is the case with a gas turbine burner Consequently, hitherto, a fuel with calorific value has been commonly added high as fuel

  additional to gas with low calorific value Cepen-

  In addition, such an addition of fuel with a high calorific value in the case of the combustion of a gas with low power

  is disadvantageous from the point of view of the cost of operation

  and as a means of substituting high energy

  As a result, we wanted to find a process ensuring sufficient and stable combustion of gases with low calorific value without adding fuel with high calorific value, as well as a burner to carry out

this combustion.

  An object of the present invention is to provide a combustion process, in which a gas with low calorific value can be burnt without adding fuel with

high calorific.

  Another object of the present invention is to provide a pro-

  of combustion, in which one can burn sta-

  ble a gas with low calorific value under a high combustion load and over a wide range of operating conditions. t 5

  Another object of the present invention is to provide a burner

  them to burn a gas with low calorific value, suitable

  requested to implement the combustion process described in c 5 above? nventb-ion suggests that part of the gas with low o-uvor c'orirque silk derivative, mixed with air at a r 2 rpr- rt air / fuel practically theoretical and burnt -agonally to form stable pilot flames, while the

  hchnaiour released from pilot flames is used to maintain

  provide stable combustion of low calorific gas

  -that residual, in the form of main combustion.

  The present invention will be better understood on reading

  the detailed description, given below as an example

  only, from a preferred embodiment, in connection with the attached drawing, in which: FIG. 1 is a plan view showing an embodiment of the present invention; Figure 2 is a sectional view taken along the line II-II of Figure 1; and Figure 3 shows the relationship between the low calorific air-gas mixture ratio and the flame temperature.

  We will now describe an embodiment of the present in-

  vention referring to the attached drawing In Figures 1

  and 2, in the center of a burner, there is provided a

  liquid bustible 1; starting from the position of this atomi-

  sor 1 outward towards the periphery of the

  burner, there is successively a crown of power-

  air 2 for the pilot flame, 3 A gas injection holes with low calorific value for the pilot flame,

  a low calorific gas supply ring

  fig 4 for main combustion and a crown of fuel

  air mentation 5 for the main combustion The air supply crown 2 for the pilot flame comprises a multiplicity of blades 2 A to cause the current to swirl

  air, and the low calorific gas injection holes

  for the pilot flame consist of large

  holes 3 A arranged at regular intervals on a circumference

  ce Low-calorific gas supply crown

  rifique 4 has 4 A blades to swirl the

  gas flow, and the air supply crown 5 com-

  carries 5 A vanes to swirl the air flow.

  A supply of liquid fuel passes according to a

  jet of liquid fuel 6 and is injected by the atomizer of liquid fuel 1 The air for the pilot flame follows an air path 9 defined by an internal burner tube 7 and an external burner casing 8, then it follows air paths 10 and 11 and is then injected by swirling through the slots between the vanes 2 A to swirl the air stream The low calorific gas for

  the pilot flame follows gas paths 12 and 13 and is

  subsequently injected through the 3 A round holes.

  Low calorific gas for main combustion

  cipale follows gas paths 14, 15 and 16 and is then injected by swirling through the slots between the blades 4 A to swirl the gas stream The air for the main combustion follows air paths 9 and 17 and is then injected by swirling through the

  slots between the blades 5 A to swirl the neck

rant of air.

  As noted above, the low calorific gas

  rific from gas generating equipment, such as a blast furnace in the steel industry, is divided into two parts, namely a small part for the pilot flame and the remaining part for the main combustion, and each part is injected -by respective injection openings The gas with low calorific value that has been derived for the pilot flame is then mixed with air for the pilot flame according to an optimal mixing ratio as seen on the figure 3 to ensure combustion

  sufficient and form a stable pilot flame The gas at low

  ble calorific value for main combustion

  reads the heat given off by the pilot flame and, therefore,

  can burn stably Then variations in -

  burner operating conditions (variations in flow

  fuel gas) are corrected by the

  low calorific gas bit for main combustion through a mounted flow control valve

  in the intermediate portion of a pipe (not shown

  sensed), connected to the gas path 14, and the gas with low calorific value for the pilot flame is brought to a constant predetermined flow rate, so that the stability of the pilot flame can be maintained by adopting an air mixture ratio -Gas with low optimal calorific value nearby

  the theoretical mixing ratio for sufficient combustion

health.

  As described above, according to the present invention,

  part of the gas with low calorific value is constantly

  derivative at a predetermined rate and this derivative gas steadily forms the stable pilot flame Combustion

  gas with low calorific value for main combustion

  cipal is maintained by the heat given off by the flame

  pilot, and variations in operating conditions

  the burner are corrected by adjusting the gas flow rate with low calorific value for the main combustion so that stabilized flames can be obtained under high combustion load over a wide range of operating conditions.

Claims (6)

Claims   1 Method for burning a gas with low calorific value,   characterized in that part of the low calorific gas   rifique is derived, constantly mixed with air for a pilot flame at an optimal mixing ratio, and then burned, and in that in addition the variations in the operating conditions of a burner are corrected by adjusting the remaining part of the low calorific gas for main combustion.   2 A method for burnt gas with low calorific value according to claim 1, characterized in that this gas is divided into two parts, namely a small part for the   pilot flame and the remaining part for main combustion   cipal, in that each part is injected by openings   respective injection tures, and in that the gas with low calorific value for the pilot flame is mixed with flair for the pilot flame at an optimal mixing ratio   for combustion so as to form a stable pilot flame.   3> Method for burning a gas with low calorific value according to claim 2, characterized in that the flow rate of the gas with low calorific value for the main combustion   is controlled by means of a flow adjustment valve for   changing Igaz with low air calorific value for main combustion.   4 Burner for burning a gas with low calorific value, characterized in that, from the center of the burner, going outwards to its periphery, there is successively an air injection opening (2) for pilot flame, a low calorific gas injection opening (3 A) for the pilot flame, a low calorific gas injection opening (4) for the main combustion and a gas injection opening air (5) for main combustion.   Burner for burning a low calorific gas according to claim 4, characterized in that the air injection opening (2) for the pilot flame, the low calorific gas injection opening (3 A ) for the pilot flame, the low-pressure gas injection opening   see heat (4) for main combustion and   air injection valve (5) for main combustion   are arranged respectively on concentric zones.   6 Burner to burn a gas with low calorific value   according to claim 4, characterized in that vanes -   (2 A, 4 A, 5 A), intended to create turbulence, are provided in the air injection opening for the pilot flame,   in the low-calorific gas injection opening   for main combustion and in the combustion chamber   air jection for the main combustion respectively, and in that the low calorific gas injection openings for the pilot flame are constituted by a   multiplicity of round holes (3 A).