FR2481416A1 - METHOD AND APPARATUS FOR ADJUSTING COMBUSTION - Google Patents

Abstract

PROCESS AND APPARATUS FOR REGULATING COMBUSTION. IN THIS PROCESS AND THIS APPARATUS, THE VOLUME OF COMBUSTION AIR IS ADJUSTED ACCORDING TO VARIATIONS IN THE LOAD, THE VOLUME OF AIR IS MEASURED, AND THE VOLUME OF FUEL IS ADJUSTED ACCORDING TO THE RESULT OF THE MEASUREMENT OF THE VOLUME OF AIR. THEREFORE, THE ADJUSTMENT OF THE COMBUSTION CAN BE CARRIED OUT ACCORDING TO THE VARIATIONS OF THE LOAD WHILE THE RATIO OF THE VOLUME OF COMBUSTION AIR TO THE VOLUME OF FUEL NECESSARY FOR COMBUSTION IS MAINTAINED SENSITIVELY CONSTANT. APPLICATION: ESPECIALLY TO BLOW AIR BURNERS EQUIPPING BOILERS OF THE HOT WATER TANK TYPE.

Description

i

  Process and apparatus for controlling combustion

  The present invention relates to a method and apparatus for adjusting the combustion in a blast furnace, the combustion air being supplied and

  under pressure and the adjustment of the combustion

  killing according to changes in the load while the ratio of combustion air to fuel is maintained

substantially constant.

  In the equipment of domestic air blast burners according to the prior art, an intermittent combustion process has been adopted as a means of controlling combustion in order to be able to respond to changes in the load. However, this method has raised a difficulty which lies in the fact that the precision with which the adjustment of the combustion is made is only + 5 C compared to

  the set temperature, so that the comfort of the users

  is not insured. On the other hand, an elevation of at least 5 ° C means that more fuel is burned than is necessary, which is not desirable from the point of view

  this is the conservation of energy. In particular, a boiler

  The type with pallet Q hot water is intended to store a

  large volume of chauae water and maintain it at a

  high level in order to respond to a continuous demand

  a large amount of hot water, so that the temperature

  The hot water in the flask is measured at all times and the combustion is restarted as soon as the temperature of the hot water falls. From the point of view of the conservation of

  energy, this type of boiler therefore requires perfection-

  more urgent than home heating equipment

mentioned above.

  With regard to the blast air combustion system, a known method of controlling combustion has been heretofore provided in which a control valve is operated by the combustion air pressure and wherein fuel required for combustion is provided

  Roperally to the displacement of the control valve.

  In this system of combustion, it is the volume of air only that is regulated according to the variations of the load. This

  combustion system proved undesirable as

  the combustion is strongly influenced by the conditions

  outside air. For example, a rise in atmospheric pressure would increase the static pressure to

  leaving the fan, making it impossible to ob-

  volume retention Desired air. The result would be

  of soot and carbon monoxide when the fuel

  tilise is a gas other than natural gas, in particular liquefied petroleum gas and butane gas having a strong

  carbon content, or a liquid fuel. In these circumstances

  In this case, it is hesitant to adopt this system of combustion control.

  The present invention has been developed to avoid

  the disadvantages of this prior art listed above.

  Accordingly, the object of the present invention is to provide

  a process and apparatus for controlling combustion,

  readable in a combustion air system which is

  free from the production of soot and carbon dioxide.

  ) The present invention is based on discovery

  that the air has a certain force of inertia. The characteristic

  The salient feature of the present invention is the

  the air volume is first adjusted and the fuel

  tiDle is supplied for combustion according to the volume

  I have air settled. Because of this characteristic, the volume of air varies smoothly depending on the load variations, so as to avoid the appearance of soot or oxide

  a cdrmone that could come from a momentary supply of air

munt insufficient.

  The present invention will be well understood in reading

  rc of the following nescrijtion made in relation to the óus-

  in which: - Figure I is a characteristic sciea.a G'urI

  t. And the use of a sui generis system.

  2 & 't,' - tj ul. The use of a data collector

  tjUlUlt; - lai f ijuru 2 is a sculema of education and technology. The invention is incorporated in a combustion system using a gaseous fuel. FIG. 3 is a sectional view of a fuel control valve used in the fuel control apparatus. combustion of a gaseous fuel, shown in Figure 2;

  - Figure 4 is a diagram representing the

  Rac-Gristes of the valve regulating a fuel

  zex, shown in Figure 3; and FIG. 5 is a sectional view of another form of gaseous fuel control valve, shown in FIG.

Figure 3.

  We will describe now.the present invention in re =

  bearing on the examples of realization shown on the

drawings.

  FIG. 1 represents a boiler of the balancing type

  of hot water, using liquid fuel and

  the apparatus which is the subject of the present

  the invention. The combustion system includes a burner 1

  blower equipped with a main heat exchanger 2-

  to transmit heat from a hot spring at high temperatures

  and a circulating pump 3 for circulating a C cycle to a hot fluid to transmit heat to a load. In the cycle C are mounted temperature sensitive sensors 4A and 4B for detecting the temperature of the hot fluid, an indirect heat exchanger 4 for transmitting the heat

  from the hot fluid to the tap water, a radiator 6 for

  berate the heat transferred by the hot fluid into a room, and three-way valves 7 and 8 for setting respectively a hot water feedstock and a heating load. A fan 10 supplies the burner 1 with combustion air and comprises a duct 11 of air which divides

  in a primary air duct 11A communicating the fan

  tilaneur 10 with the carburetor 1A of the burner 1, and a

  11B secondary air putting the fan 10 in communi-

  1. Carburetor 1A is a spray carburettor with a rotating disc

  to spray the liquid fuel and spread the

  pulverized particles of the latter. The fan 10 is

  dragged by a motor, the rotation is regulated by a cir-

  baked 13 on the basis of signals emitted by the temperature-sensitive detectors 4A and 4B and mounted in the cycle C. In the air duct 10 of the fan 10, a detector is mounted

  14 airflow, such as a hot wire anemometer. Com-

  liquid fuel is contained in a fuel tank 15

  ble with a regulator 16 static level of the liquid, and it is sent to the burner 1 by a fuel pump 17 controlled by a circuit 1l frequency control which is in turn controlled by a signal from the detector 14 debit. Reference 9 denotes a water supply

  hot coming from the indirect heat exchanger 4.

  In operation, the heat from the gas to

  high temperature is transmitted to the hot fluid whose temperature

  The temperature rises to a high value. This hot fluid at room temperature

  high temperature yields heat to provide hot water supply or space heating, resulting in a drop in fluid temperature

  hot. The hot fluid at low temperature is brought back to the

  main heat changer 2. The temperature of the hot fluid

  in circulation may vary according to the load of food

  hot water or heating load. What is

  that the higher the load, the higher the temperature

  The temperature detected by the temperature detectors 4A or 4B is low. We will describe the operation by referring to the

  temperature of the hot water supply. The arrival (volu-

  With the burner 1 being constant, the temperature of the circulating hot fluid decreases as the amount of hot water supplied increases. If the normal temperature of the hot fluid is set in advance and if you try

  to maintain this temperature at the normal level despite the

  of the load, it will be necessary to increase the inflow of

  1. The temperature of the hot fluid is detected

  temperature sensitive detectors 4A and 4B, and the voltage measured by these detectors is compared with a

  voltage representing the normal normal temperature of the fluid

  in the circuit 13 for adjusting the rotation of the motor.

  the burner fan, to determine

  rotation of the motor 12 of the burner fan. From this

  However, the volume of air required for combustion is determined

born before the fuel volume.

  The air flow rate sent to the burner 1 is measured by the air flow detector 14 which sends a signal to the circuit 18 which adjusts the frequency. The volume of fuel that

  is sent to the Drummer 1 by the fuel pump 17, is

  se on the relation expressed by the formula below. Of the-

  the airflow sensor 14 may be in the form of a

  electric manometer, although it was mentioned in the description

  the use of a hot wire anemometer.

  Air Volume Required to Burn a Specified Volume of Fuel (A) Constant Determined Fuel Volume (F) (K) O ......... (1)

  In combustion according to this formula, flames

  my have a general tendency to color in yellow because the value of A is reduced compared to that of F, causing

  thus creating soot. Conversely, the flames tend to

  to rise when the value of A is increased by

  port to that of F. When the main heat exchanger 2

  is an aluminum heat exchanger with internal fins

  If a sheet-metal fin type heat exchanger is used, it will be necessary to avoid clogging it with the soot produced by the flames. For this purpose, the value of A is first set and then the value of F is determined in accordance with the present invention, so that the influences which could

  be exercised by a delay of F with respect to A,

  worm the flames rather than make them turn yellow,

  to avoid the risk of soot creation.

  In the exemplary embodiment shown and described above, the points o are placed the temperature-sensitive detectors 4A and 4B and the air-flow detector 14 can of course be chosen according to the objective to be measured. adjust. This is equivalent to saying that when the temperature of the water is the target, the temperature of the hot water at the outlet can be detected. Similarly, when the combustion system is a system in which

  the burner burns the fuel entirely with the primary air

  a system in which the primary air volume de-

  terminates the operation of the burner, the air flow sensor 14 can be placed in the duct liA primary air. In the exemplary embodiment shown and described above, we have

  discloses a rotary disk carburetor

  being the means used to pulverize

  quide. It should be understood that the present invention is not limited to this particular form of liquid fuel spraying means, and that a jet spray system using pressure or a venturi spray system utilizing the same can be used. air. In the realization

  the present invention, it has been observed that the pulse system

  Rotary disk actuation was the most efficient. The reason

  This is due to the fact that the spraying of

  which can be done in a stable way because the central force

  trifuge remains constant, even if the load varies and if the

  lume of fuel also varies, since spraying

  liquid fuel is produced in the spray system.

  rotating disk using centrifugal force

  rotating disk whose rotational speed remains constant.

  Figure 2 represents another example of

  which is incorporated in a combustion system using a gaseous fuel. Parts similar to those shown in FIG. 1 are identified by identical references. In the present embodiment, the method

  leading to the application to a control cock 23 of the com

  a signal based on the signal of the air flow sensor 14 is similar to the corresponding method followed in the embodiment shown in FIG. 1, so that

  we will not give a description. In the example of

  The embodiment shown in FIG. 2, the aerated fuel coming to the outside under a predetermined pressure, is introduced into a pressure regulator 22 after having passed through a valve 21 with electromagnetic control. The pressure regulator 22 serves to maintain the pressure of the secondary side substantially constant without being based on the

  pressure on the primary side. The relative positions of the

  electromagnetically controlled poppet 21 and regulator 22 of

  pressure can be reversed. The fuel coming from the

  pressure regulator 22, under a constant pressure, is supplied to the fuel volume control valve 23 in which this volume is adjusted, according to the formula (1), so that the volume of fuel which supplies the

  Burner 1 is proportional to the volume of air.

  The fuel volume adjustment valve 23 can be any type of valve known, for example

  the fuel volume control valve 23 is a

  electromagnetically controlled pope of known type, whose cour-

  plunger piston continuously varies with the voltage.

  The fuel volume control valve 30, shown in FIG. 3, adjusts the fuel volume as follows: a piston 33 is displaced by the force resulting from an electromagnetic force produced in an electromagnet 31 by the voltage applied to it, and the thrust force of a spring 32, this displacement of the piston controls the displacement of a needle 34 which is coupled to it, so as to

  to vary the free section of an opening 35 in the seat

  the valve to adjust the fuel volume. The

  valve 30 comprises a gas inlet duct 36 and a

gas outlet 37 outlet.

  The valve 30 for adjusting the fuel volume

  gas creates a hysteresis due to the residual magnetism of the

  mant. Figure 4 shows the characteristics of the

  pe. In the diagram shown in Figure 4, the abscissa

  presents the tension and the ordinate the plunger piston stroke

  It will be understood that a variation of the charge causes a change in

  The influence of the residual magnetism appears at the point where the direction of the reverse stroke is reversed. At this point, there is no variation in the displacement of the plunger despite the fact that the tension

  be recaked. When using an electrically controlled valve

  which works in this way, the volume of

  fuel varies according to the direction of piston movement

  diver and, therefore, it is impossible to obtain a report

  constant port of the air / fuel mixture. The gap caused by the hysteresis can sometimes be of the order of 200% and, therefore, the use of this valve as a control valve is limited. In the diagram of FIG. 4, the curve I represents the case of a load of 37 g and the curve II that of

a load of 100 g.

  The valve 40, shown in FIG. 5, was half

  in order to eliminate the disadvantages mentioned

  above the fuel volume control valves according to the prior art. The characteristic of the valve 40

  lies in the fact that it is based on a process

  all or nothing to adjust the fuel volume.

  More precisely, the time during which the seat of the

  pope is open is determined by the length adjustment

  the time during which the valve is open or by the name

  many times it's open. The valve seat, identified by references 41 and 42, operates in such a way that

  movable member 41 of the seat, moved vertically by the

  this electromagnetic and the force of a spring, enters into

  tact with the fixed member 42 of the seat or departs from it. When the movable member 41 and the fixed member 42 of the seat are in contact with each other, the gas flow is stopped, and when these organs are spaced apart from each other, the gas flow can cross the valve. By adjusting the time during which the two seat members 41 and 42 are in contact with each other and the time during which they are spaced from each other, the valve can be opened and closed completely. The valve 40 has no hysteresis as is the case of the valve 30 shown in Figure 3. In Figure 5, the parts identical to those of Figure 3 have been identified

by identical references.

  We must realize, from the description

  above, that the combustion control system

  the present invention, wherein the fuel and the air

  are set to obtain a sensible air / fuel ratio

  constant at all times, works in such a way that the air volume is first adjusted according to a variation

  load, the volume of air is measured, and then the volume

  me of burning fuel is settled on the basis of the measure

  to volume & air. Because of this characteristic, the pre-

  invention provides a method and apparatus for performing

  kill the combustion control, which allows to use the inertia force of the air by varying the volume of air

  smoothly as a function of load variations, of

  to avoid the appearance of soot and carbon

  otherwise, it could be due to an air supply that is momentarily insuf-

  despite an increase or decrease in fuel volume. The present invention is not limited to the examples

  a realization which have just been described, it is on the contrary

  subject to variations and modifications which

to the man of the art.

Claims (7)

  A method of controlling combustion in which the control of combustion is effected in response to changes in the charge while maintaining substantially constant the ratio of the combustion air volume to the volume of fuel to be burned, which method is characterized in that what   it includes the stages of adjustment of the air volume according to a vari-   charge; measuring this volume of air; and volume adjustment   of fuel depending on the measurement of the volume of air.   2. Apparatus for regulating the combustion in which the adjustment of combustion is effected according to the variations of the charge while maintaining substantially constant the ratio of the volume of combustion air to the volume of fuel to be burned, this apparatus being characterized in this   it comprises a burner (1); means (4A, 4B) for detecting a variation   charge; fan means (10) for supplying air to the burner; means (13) for adjusting the drive means of the fan means, based on a signal from the detecting means; means (14) for measuring the air flow mounted on the discharge side of the means   fan to measure the volume of air proportional to the   loadings; means (17) for feeding the fuel to the burner   their; and adjusting means (18) for adjusting the fuel   based on a signal created by the means for measuring the air flow rate as a result of the measurement of the air flow, in order to send to the burner, from the fuel supply means, a volume of fuel proportional to the volume of air measured by the means for measuring the flow rate air.   An apparatus for adjusting the combustion according to claim 2, characterized in that the fuel is a liquid fuel; and in that the burner (1) comprises a carburettor (1A) for spraying   rotary disc (20) which comprises a rotating disc for spraying and   fuse the liquid fuel in the form of pulverized particles.   4. Apparatus for adjusting the combustion according to claim 2, characterized in that the fuel is a gaseous fuel, and   the fuel supply means is an electromagnetic valve   gnetic (40) of the type of setting all or nothing.   5. Apparatus for controlling combustion according to any one   Claims 2 to 4, characterized in that the means (14) for measuring   the air flow includes a hot wire anemometer.   6, Apparatus for regulating combustion according to claim   2, characterized in that the combustion apparatus is blown air.   7. Apparatus for adjusting the combustion according to claim 6, characterized in that the burner (1) of the air combustion apparatus   blown is a burner for boiler type hot water tank.