CN1126907C - Industrial furnace with high-temperature low-oxygen air burner - Google Patents

Abstract

An industrial furnace with a high-temperature and low-oxygen air burner relates to a high-temperature and low-oxygen combustion technology and equipment. The present invention aims at the defects of high NOx emission and low energy utilization rate caused by the lack of low-oxygen combustion technology in the currently used industrial furnaces, and provides an industrial furnace with a low-oxygen air burner, which is characterized in that A high-temperature and low-oxygen air burner is respectively arranged at both ends of the furnace. The burner is composed of a combustion chamber, a combustion chamber end cover arranged at the combustion chamber port, the center of which is a circular through hole and an annular channel is formed at the end of the combustion chamber, and a set It consists of a cover plate on the end cap. This burner can make the oxygen in the high temperature air be diluted by the return flue gas to become hypoxic air, so that the fuel can be ignited and burned under the condition of hypoxic air, and the oxygen concentration is not higher than 15%. Not only the NOx emission is effectively reduced, but also the exhaust gas temperature is only 150°C to 200°C, so the exhaust smoke loss is small and the energy utilization rate is high, achieving the purpose of energy saving and environmental protection.

Description

Industrial Furnaces with High Temperature Low Oxygen Air Burners

technical field

The invention belongs to a high-temperature and low-oxygen combustion technology and equipment, in particular to an industrial furnace with a high-temperature and low-oxygen air burner.

Background technique

Due to its excellent energy-saving and environmental protection effects, high-temperature low-oxygen combustion technology is the development direction of industrial furnaces all over the world. However, most of the existing industrial furnaces or various fuel oil and gas heating furnaces designed and manufactured by China's metallurgical system did not use low-oxygen combustion technology, but directly contacted high-temperature and high-oxygen-concentrated air with fuel to ignite and burn , resulting in high NO _x emissions, large smoke loss, and low energy utilization. For example, the melting glass furnace used in the prior art is exactly one of them, and its structure generally consists of a furnace, fuel (coal-water slurry or gas fuel) spray gun, regenerative heat exchanger, blower fan, induced draft fan and four-way reversing valve And other components, the fuel is injected into the furnace and ignites and burns directly, so it is easy to cause large smoke exhaust loss and high _NOx emissions, which does not meet the requirements of energy saving and environmental protection.

Contents of the invention

The purpose and task of the present invention is to provide a kind of industrial furnace with high-temperature low-oxygen air burner for the deficiencies and defects of the prior art, so that it can effectively reduce the emission of _NOx , and the exhaust smoke loss is small, and the energy utilization rate is high. High, so as to meet the requirements of both energy saving and environmental protection.

The present invention is achieved through the following technical solutions: an industrial furnace with a high-temperature and low-oxygen air burner, which mainly consists of a furnace, fuel spray guns respectively arranged on the left and right sides of the furnace, a regenerative heat exchanger, and pipes respectively It consists of a four-way reversing valve connected with the blower, the induced draft fan and the regenerative heat exchanger. It is characterized in that a high-temperature and low-oxygen air burner is respectively installed at both ends of the furnace. The burner is composed of a combustion chamber and a set The end cover of the combustion chamber at the port of the combustion chamber and the cover plate arranged on the end cover; the end cover is fixed on the wall of the combustion chamber, and forms an annular channel with the wall of the combustion chamber, and the center of the end cover is provided with a central passage hole.

The above-mentioned technical scheme can make the high-temperature air flow into the combustion chamber from the annular passage at a relatively high speed, and then form an annular jet. Because the annular jet has a great entrainment effect, the combustion chamber becomes a negative pressure. At this time, a large amount of flue gas (without oxygen) flows back into the combustion chamber, is entrained by high-temperature air and mixed with it, making the high-temperature air Diluted into high-temperature and low-oxygen-concentration mixed gas, because of its high temperature, it will catch fire and burn after it contacts with fuel, thus realizing high-temperature and low-oxygen air combustion.

The above-mentioned annular channel can also be designed as a swirl channel, that is, swirl vanes are arranged in the annular channel. In this way, the high-temperature air enters the combustion chamber in a rotating motion through the swirl channel, and its entrainment effect is greater, and the flue gas returns more. After mixing with the high-temperature air, the air is diluted to a greater extent.

Compared with the prior art, the present invention has the following advantages and beneficial effects: the present invention forms a recirculation zone in a limited space (i.e., the combustion chamber) due to the high-temperature and low-oxygen air burners being arranged at the front and rear ends of the furnace. The flue gas (without oxygen) is mixed with the air with high temperature and high oxygen concentration, so that the oxygen in the high temperature air is diluted by the flue gas to become a low oxygen concentration. Since the air is preheated to 800°C to 1100°C, the fuel can still catch fire and burn. In this way, under the condition of low oxygen air concentration, the NOx emission of fuel combustion is relatively low, and the exhaust gas temperature is only 150°C-200°C, so the loss of exhaust smoke is small, and the energy utilization rate is high, which not only saves energy, but also can achieve Environmental requirements.

Description of drawings

Figure 1 is a structural schematic diagram of an industrial furnace with a high-temperature low-oxygen air burner.

Figure 2 is a schematic diagram of the structure and principle of the high-temperature low-oxygen air burner.

Figure 3 is a schematic diagram of the combustion chamber end cover.

FIG. 4 is a cross-sectional view along line A-A of FIG. 3 .

Figure 5 is a schematic diagram of the combustion chamber cover.

Fig. 6 is a schematic structural diagram of a swirl channel with swirl blades installed in the annular channel.

Detailed ways

Below in conjunction with accompanying drawing, describe concrete structure of the present invention, operating principle, working process and embodiment in detail: Fig. 1 is a kind of industrial furnace structural representation with high-temperature low-oxygen air burner, and it is mainly arranged on respectively by furnace hearth 8 Fuel spray guns 6 on the left and right sides of the furnace, electromagnetic valve 4, animal heat exchangers 5, 10, blower 1, induced draft fan 3 and four-way reversing valve 2, etc. are composed. A high-temperature low-oxygen air burner is respectively arranged at the left and right ends of the furnace 8, and the burner (Fig. Composed of 16. The end cover of the combustion chamber and the wall surface of the combustion chamber form an annular air intake passage. Fig. 3 is a kind of embodiment of the present invention, is provided with 3～5 supporting claws on the end cover 15, can form an annular air inlet channel, and there is an openable cover plate 16 on the end cover 15 (see Fig. 5) , and the end cover 15 is hinged. The end cover 15 is fixed on the wall of the combustion chamber. High-temperature air (900°C-1100°C) flows into the combustion chamber from the annular channel at a speed of 10m/s-30m/s, forming an annular jet. This annular jet has a great entrainment effect in the limited space of the combustion chamber, thereby making the combustion chamber a negative pressure. At this time, a large amount of flue gas (without oxygen) flows back into the combustion chamber, entrained by high-temperature air and mixed with it, so that the high-temperature air is diluted into a high-temperature and low-oxygen-concentration mixture. The oxygen concentration of the mixed gas at the combustion chamber outlet 11-14 section depends on the distance between the combustion chamber end cover 15 and the combustion chamber outlet 11-14 section, that is, the depth of the combustion chamber. The greater the depth, the lower the oxygen concentration of the mixture at the cross section of the combustion chamber outlet 11-14; otherwise, the higher the oxygen concentration. This depth can be adjusted by means of the relative position of the combustion chamber end cover 15 to the section of the combustion chamber outlet 11-14. When the oil gun on the same side is working, the cover plate 16 is closed; and when the oil gun on the opposite side is working, the cover plate is opened by the pressure of the flue gas, ensuring that the flue gas can freely enter the regenerative heat exchanger (see Figure 1 right). Fuel spray gun 6 is installed in the central position of combustion chamber, and solenoid valve 4 is housed above, and its nozzle is near combustion chamber outlet section 11-14 place.

The annular channel can also be designed as a swirl channel (see Figure 5), and swirl vanes 17 can be installed in the annular channel. When the high-temperature air passes through the swirl channel 18 and enters the combustion chamber in a rotating motion, its entrainment effect is greater, and the flue gas returns more. After mixing with the high-temperature air, the air is diluted to a greater extent. Therefore, if you want to obtain a burner with a lower oxygen concentration, you can use this method. However, the general DC annular channel can meet the requirements, and its oxygen concentration is not higher than 15%. Compared with the swirl flow channel, the direct current channel is easier to process and manufacture.

Its working process is as follows: In the state shown in Figure 1, the cold air is supplied by the blower 1, enters the regenerative heat exchanger 5 on the left side of the figure through the four-way reversing valve 2, and at its outlet, the air can be preheated To 800 ℃ ~ 1100 ℃, after this high temperature air passes through a low oxygen concentration burner, it will catch fire and burn after meeting the fuel 7 sprayed out by the fuel spray gun 6 . The components of the furnace 8 or the water in the water-cooled wall tube 9 are heated, and the temperature of the flue gas drops, but it is still about 900°C to 1200°C. Through another heat accumulator 10 on the right side of the figure, the flue gas transfers energy to the accumulator. After the thermal heat exchanger 10, its temperature drops to 150°C-200°C, so the loss of smoke exhaust is small, and the energy utilization rate is high. After working for a certain period of time, that is, when the exhaust gas temperature is close to 200°C, the switch is performed, that is, the four-way reversing valve 2 is switched to the dotted line state; at the same time, the solenoid valve 4 of the left fuel is turned off, and the fuel valve of the right side is turned off. Solenoid valve 4 is opened, and fuel is injected. At this time, the cold air is fed into the heat accumulator 10 on the right by the blower 1 through the four-way reversing valve 2, and the high-temperature flue gas is discharged by the induced draft fan 3 after passing through the heat accumulator 5 on the left. When the oil gun on the same side is working, the cover plate 16 is closed; and when the oil gun on the opposite side is working, the cover plate 16 is opened by the pressure of the flue gas, ensuring that the flue gas can freely enter the regenerative heat exchanger (see Figure 1 right). Repeated cycle like this, has just realized the normal operation of high-temperature low-oxygen air combustion.

Claims (3)

1. An industrial furnace with a high-temperature and low-oxygen air burner, which is mainly composed of a furnace, fuel spray guns arranged on the left and right sides of the furnace, a heat storage heat exchanger, and a blower, an induced draft fan and a heat storage heat exchanger through pipelines. Composed of four-way reversing valves connected to type heat exchangers, it is characterized in that: a high-temperature and low-oxygen air burner is respectively installed at both ends of the furnace, and the burner is composed of a combustion chamber and a combustion chamber arranged at the port of the combustion chamber. It consists of an end cover and a cover plate arranged on the end cover; the end cover is fixed on the wall of the combustion chamber and forms an annular passage with the wall of the combustion chamber, and a central through hole is arranged in the center of the end cover. 2. The industrial furnace with a high-temperature and low-oxygen air burner according to claim 1, wherein swirl blades are arranged in the annular channel. 3. An industrial furnace with a high-temperature and low-oxygen air burner according to claim 1 or 2, wherein 3 to 5 supporting claws are arranged on the end cover of the combustion chamber.

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