JP2015105802A - Heat storage type burner and cleaning method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat storage type burner (especially including a heat storage layer comprising honeycomb type heat storage elements) capable of easily preventing damage of the heat storage layer (floatation or blowing-off of the heat storage element) due to adhesion of dust, and provide a cleaning method thereof.SOLUTION: A heat storage type burner 1 includes a fuel nozzle 2 and a heat storage layer 3 in which honeycomb type heat storage elements 4 are overlapped. On the surface layer on the side of a burner body 2 of the heat storage layer 3, net-like hardware 7 for heat storage element floatation prevention is installed.

Description

  The present invention relates to a heat storage burner and a cleaning method thereof.

  The regenerative burner has a fuel nozzle and a layer (heat storage layer) in which the heat storage elements overlap. At the time of combustion, the combustion air is heated through the heat storage layer and then used for combustion of the fuel gas from the fuel nozzle. During combustion, the combustion exhaust gas is passed through the heat storage layer to store heat in the heat storage layer.

  At that time, as the heat storage body, a honeycomb-shaped heat storage body (honeycomb-type heat storage body), a ball-shaped heat storage body (ball-type heat storage body), or the like is used. The material used is ceramic, alumina, or refractory metal.

  And usually, a regenerative burner is used in pairs to perform alternating combustion. That is, when one of the heat storage type burners is burning, the other heat storage type burner performs non-combustion to store heat in the heat storage layer and repeats the reverse when a predetermined time has passed.

  In the heat storage type burner, the combustion air heated in the heat storage layer is mixed with the fuel gas and then supplied into the fuel nozzle, or the combustion air heated in the heat storage layer is supplied into the fuel nozzle. There are types, a type in which combustion air heated in the heat storage layer is supplied to the vicinity of the fuel nozzle, and the like.

  Such a regenerative burner is attached to a heating furnace for heating a steel material to be hot-worked to a predetermined temperature, for example, but has the following problems.

  That is, the steel material to be hot-worked is heated to about 1100 to 1200 ° C. in a heating furnace. As the temperature of the steel material rises in the heating furnace, a scale is generated on the surface of the steel material, and part of the scale peels off from the surface of the steel material and floats in the heating furnace. In addition, the soot generated by local incomplete combustion and particles generated by refractory deterioration are floating in the heating furnace. When these react and form a low-melting-point substance (dust), the dust adheres to the heat storage body, and deposits (dust) accumulate on the heat storage body, which may cause clogging of the heat storage layer.

  When the blockage of the heat storage layer proceeds, pressure loss of combustion air and combustion exhaust gas that passes through the heat storage layer increases (flow path resistance increases). For this reason, the pressure acting on the heat storage layer is increased, and the floating of the heat storage body disposed above the heat storage layer is likely to occur. In this state, when high-load combustion with a large flow rate of combustion air is performed, the suspended heat storage body blows off into the furnace together with the combustion air. When the heat storage body at the upper part of the heat storage layer blows into the furnace, the heat storage bodies that are adjacent to the bottom of the heat storage layer float one after another and blow into the furnace together with the combustion air. As a result, the number of heat storage bodies decreases, and the heat exchange efficiency between the heat storage layer and the combustion air and between the heat storage layer and the combustion exhaust gas is significantly reduced. Moreover, in order to eliminate this decrease in heat exchange efficiency, it is necessary to stop the operation of the heating furnace and repair and replace the heat storage layer, resulting in expensive repair and replacement costs and long-term loss of operation opportunities. Will be invited.

  As techniques for dealing with such damage to the heat storage layer (floating / blowing of the heat storage body), techniques described in Patent Documents 1 and 2 and Patent Document 3 are known.

  The technologies described in Patent Documents 1 and 2 are technologies for collecting dust by cooling the dust, or technologies for preventing dust adhesion by heating the heat storage body itself to a temperature equal to or higher than the melting point of the dust. is there.

  Patent Document 3 describes a technique for removing the adhering matter by applying vibration to the ball-type heat accumulator as a technique for removing the adhering matter adhering to the surface of the ball-type heat accumulator.

Japanese Patent Laid-Open No. 7-119958 U.S. Pat. No. 4,944,670 JP 2007-309597 A

  However, in the case of the techniques described in Patent Documents 1 and 2, in order to realize cooling of dust or heating of the heat storage body, it is necessary to add a cooling function or a heating function to the heat storage burner. Remodeling is required.

  Further, in the case of the technique described in Patent Document 3, applying vibration to the heat storage body may cause damage to the heat storage body, and in particular, applying vibration to the honeycomb type heat storage body having a lower strength than the ball type heat storage body. There is a danger of causing cracks in the heat storage body, resulting in damage to the heat storage layer.

  Therefore, until now, there has been no efficient countermeasure against damage to the heat storage layer (floating / blowing of the heat storage body) due to dust adhesion.

  The present invention has been made in view of the above circumstances, and in a heat storage type burner (particularly, a heat storage type burner having a heat storage layer by a honeycomb type heat storage body), the heat storage layer is damaged due to adhesion of dust. It is an object of the present invention to provide a heat storage burner that can easily prevent (floating / blowing of a heat storage body) at low cost and a cleaning method thereof.

  In order to solve the above problems, the present invention has the following features.

  [1] A heat storage burner comprising a fuel nozzle and a heat storage layer in which heat storage bodies are stacked, wherein a reticulated burner is provided on the surface layer of the heat storage layer on the fuel nozzle side.

  [2] The heat storage burner according to [1], wherein the heat storage body is a honeycomb heat storage body.

  [3] The method for cleaning a regenerative burner according to [1] or [2], wherein dust attached to the regenerator is removed by performing high-load combustion with the regenerative burner. Cleaning method for regenerative burner.

  According to the present invention, in a heat storage type burner (particularly, a heat storage type burner having a heat storage layer made of a honeycomb type heat storage body), damage to the heat storage layer (floating / blowing of the heat storage body) due to adhesion of dust can be reduced at a low cost. This can be easily prevented.

It is a figure which shows one Embodiment of this invention.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a view showing a regenerative burner according to an embodiment of the present invention.

  As shown in FIG. 1, a regenerative burner 1 according to an embodiment of the present invention is installed on a furnace wall 11 of a heating furnace 10, a fuel nozzle 2 attached to the furnace wall 11, and one end of a heating furnace. 10 is housed in a casing 8 opened toward the inside, and includes a heat storage layer 3 in which honeycomb-type heat storage bodies 4 are stacked in layers. During combustion of the regenerative burner 1, combustion air is heated through the heat storage layer 3 and then supplied to the vicinity of the injection port of the fuel nozzle 2 to be used for combustion of the fuel gas injected from the fuel nozzle 2. When the regenerative burner 1 is not combusted, the combustion exhaust gas is passed through the heat storage layer 3, and the sensible heat of the combustion exhaust gas is stored in the heat storage layer 3.

  The regenerative burner 1 is used in pairs with another regenerative burner 1 (not shown) to perform alternating combustion. That is, when one regenerative burner 1 is combusting, the other regenerative burner 1 performs non-combustion to store heat in the heat storage layer 3 and repeats the reverse when a predetermined time has elapsed. .

  Here, as a cradle for the heat storage layer 3, a grating 6 supported by the support 5 is laid on the lowest end of the heat storage layer 3 (surface layer opposite to the fuel nozzle 2), and the heat storage layer is formed on the grating 6. 3 (honeycomb type heat storage body 4) is loaded.

  In addition, in this embodiment, a net-like metal piece 7 for preventing the heat storage body from floating is provided at the uppermost end (surface layer on the fuel nozzle 2 side) of the heat storage layer 3. In addition, it is preferable to fix the net-like metal object 7 to the casing 7 when there is a possibility of moving when the combustion air or the combustion exhaust gas passes.

  Thereby, in this embodiment, since the honeycomb-type heat storage body 4 is prevented from floating and blowing off by the net-like metal object 7, damage to the heat storage layer 3 due to dust adhesion can be easily prevented at low cost. Can do.

  However, even in this heat storage type burner 1, if it is used for a long time, the amount of dust attached to the honeycomb type heat storage body 4 increases, and sufficient heat exchange cannot be performed in the heat storage layer 3, and after passing through the heat storage layer 3. Changes such as a decrease in temperature of combustion air and an increase in pressure loss occur. In addition, since it is difficult for the combustion exhaust gas to exchange heat with the heat storage layer, the combustion exhaust gas in the high temperature state flows into the exhaust gas duct, and the exhaust gas switching valve and the exhaust gas scavenging valve installed in the exhaust gas duct are exposed to the high temperature combustion exhaust gas. Damage.

  Therefore, when the temperature or pressure of the combustion air after passing through the heat storage layer 3 or the temperature or pressure of the combustion exhaust gas after passing through the heat storage layer 3 is measured, and the measured value exceeds a predetermined allowable range, or The heat storage layer 3 is cleaned every predetermined period to remove dust adhering to the honeycomb type heat storage body 4.

  The cleaning method at that time is a cleaning method for removing dust adhering to the honeycomb-type heat storage body 4 by performing high-load combustion with the heat storage burner 1. Here, high-load combustion is combustion performed at 90 to 100% of the maximum combustion capacity of the regenerative burner 1. The maximum combustion capacity of the regenerative burner 1 is the maximum combustion capacity determined by the equipment limit of related equipment (exhaust gas switching valve, etc.) installed in the exhaust gas duct.

  That is, in order to remove the adhering dust from the honeycomb type heat accumulator 4, it is effective to heat the honeycomb type heat accumulator 4 to a high temperature exceeding the melting point of the dust so that the adhering dust can be easily removed from the honeycomb type heat accumulator 4. It is. Therefore, in order to increase the amount of heat stored in the honeycomb-type heat storage body 4 compared to normal operation, the amount of combustion exhaust gas sucked (exhaust gas) within a range that does not exceed the equipment limit of related equipment (exhaust gas switching valve, etc.) installed in the exhaust gas duct. Increase suction rate over normal operation. And it becomes easy to exfoliate by passing the combustion air of the flow volume increased rather than normal operation in the place where the honeycomb type thermal storage body 4 became high temperature exceeding melting | fusing point of dust by the increase in the thermal storage amount from combustion exhaust gas. Blow off the adhered dust into the furnace. By repeating this operation as many times as necessary, removal of attached dust is completed. In addition, even if the combustion air having a flow rate increased from that in the normal operation is passed, the heat storage body is fixed by the net-like hardware so that the heat storage body is not blown away by the combustion air. The exhaust gas suction rate is the ratio of the combustion exhaust gas flow rate per unit time passing through the heat storage burner to the combustion air flow rate. As the exhaust gas suction rate is higher, the flow rate per unit time through which the combustion exhaust gas passes through the heat storage body becomes larger, so the amount of heat storage increases.

  Thus, in this embodiment, since the heat storage layer 3 can be cleaned without stopping the operation of the heating furnace 10 and opening and disassembling the heat storage burner 1, the attached dust is efficiently collected. Can be removed.

  In this embodiment, as shown in FIG. 1, it is assumed that the combustion air heated in the heat storage layer is supplied to the vicinity of the fuel nozzle, but the combustion air heated in the heat storage layer is used as the fuel. The present invention can be similarly applied to a type in which the gas is mixed into a gas and then supplied into the fuel nozzle, a type in which combustion air heated in the heat storage layer is supplied into the fuel nozzle, and the like.

  Further, in this embodiment, the heat storage type burner provided with the heat storage layer by the honeycomb type heat storage body is targeted, but the same applies to the heat storage type burner provided with the heat storage layer by the ball type heat storage body. be able to.

  As an example of the present invention, the above-described regenerative burner 1 according to one embodiment of the present invention was applied to a continuous heating furnace for steel plates.

  In addition, since the net-like metal object 7 for preventing the heat storage body from floating had a weight of 10 kg, it was not fixed to the casing 8 because it could not be blown up by the combustion air.

When the heat storage type burner 1 is used for a certain period, the pressure of the combustion air after passing through the heat storage layer 3 exceeds a predetermined allowable range, so that the heat storage layer 3 is blocked by adhering matter (dust). It was judged that Therefore, the exhaust gas suction rate was increased from 70%, which is the normal operation, to 90%, and the combustion air flow rate was set to 10000 Nm ³ / Hr for high load combustion. As a result, the heat storage layer 3 was heated to a temperature exceeding the melting point of the adhering dust, and the adhering dust was blown off into the furnace by combustion air to clean the heat storage layer 3.

  When the heat storage layer 3 was inspected after cleaning, no damage such as floating or blowing of the honeycomb type heat storage body 4 was observed. There was no damage on the exhaust gas switching valve. In addition, after cleaning, the pressure of the combustion air after passing through the heat storage layer 3 falls within a predetermined allowable range.

DESCRIPTION OF SYMBOLS 1 Thermal storage type burner 2 Fuel nozzle 3 Thermal storage layer 4 Honeycomb type thermal storage body 5 Receptacle 6 Grating 7 Reticulated metal 8 Casing 10 Heating furnace 11 Furnace wall

Claims (3)

  A regenerative burner comprising a fuel nozzle and a heat storage layer on which heat storage members are stacked, wherein a reticulated burner is installed on the surface layer of the heat storage layer on the fuel nozzle side.   The heat storage burner according to claim 1, wherein the heat storage body is a honeycomb type heat storage body.   A method for cleaning a regenerative burner according to claim 1 or 2, wherein dust adhering to the regenerator is removed by performing high load combustion with the regenerative burner. .

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