Secondary combustion chamber and waste heat boiler combined pretreatment system for plasma furnace flue gas

Abstract

The utility model discloses a secondary combustion chamber and waste heat boiler combined pretreatment system for plasma furnace flue gas. The system comprises a secondary combustion chamber and a waste heat utilization boiler, an inner cavity of the secondary combustion chamber is of a U-shaped structure, an air inlet elbow joint is arranged at the upper end of the left side of the secondary combustion chamber, an air outlet elbow joint is arranged at the upper end of the right side of the secondary combustion chamber, and the right end of the air outlet elbow joint is connected with a smoke inlet in the left side of the waste heat utilization boiler. A smoke outlet is formed in the right side of the waste heat utilization boiler. The device is scientific in principle and compact in structure, flue gas exhausted by the plasma furnace is heated, combustible gas and dioxin in the flue gas are treated, denitration is performed at the same time, then heat exchange cooling treatment is performed on the high-temperature flue gas through the waste heat utilization boiler, a foundation is laid for subsequent desulfurization, desalination and spraying procedures, and the device is suitable for industrial production. And meanwhile, the generated high-temperature steam is used for the subsequent process of desalting fly ash in flue gas, so that multiple purposes are achieved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to waste gas treatment technical field, concretely relates to the two combustion chambers and waste heat boiler combination pretreatment system of plasma furnace flue gas. BACKGROUND

[0002] At present, the flue gas generated by the plasma furnace (plasma arc furnace) incineration of household garbage contains a lot of fly ash, and the flue gas composition is relatively complex, containing a large amount of salt, a small amount of combustible gas (CO, H2, CH4, VOC, NOx gas, etc.), trace amounts of dioxin and heavy metals, etc. Therefore, the flue gas generated by the plasma furnace needs to be further treated, and the current treatment method needs to use a large amount of water to fully flush the fly ash. Fly ash washing is to dissolve and extract potassium, sodium and chlorine in fly ash to produce secondary industrial products. The fly ash after water washing (also known as dechlorinated fly ash) is sent to a cement kiln for high-temperature calcination to solidify and decompose the heavy metals and dioxin in the cement kiln. This treatment method not only consumes a large amount of water and energy, but also cannot utilize the obtained crystalline salt due to too many impurities. CONTENT OF THE UTILITY MODEL

[0003] In order to solve the above technical problems in the prior art, the utility model provides a two combustion chambers and waste heat boiler combination pretreatment system for plasma furnace flue gas with small energy consumption, which first removes combustible gas, dechlorinates and removes dioxin.

[0004] To solve the above technical problems, the utility model adopts the following technical scheme: a two combustion chambers and waste heat boiler combination pretreatment system for plasma furnace flue gas, comprising a secondary combustion chamber and a waste heat utilization boiler; the inner cavity of the secondary combustion chamber is in a U-shaped structure, an air inlet elbow joint is arranged at the upper left side of the secondary combustion chamber, an air outlet elbow joint is arranged at the upper right side of the secondary combustion chamber, the right end of the air outlet elbow joint is connected with the flue gas inlet on the left side of the waste heat utilization boiler, a baffle heat exchange channel is arranged inside the waste heat utilization boiler, and a flue gas outlet is arranged on the right side of the waste heat utilization boiler.

[0005] A burner mounting port is arranged at the upper left side of the secondary combustion chamber, a burner for burning natural gas is arranged in the burner mounting port, a first SNCR spray gun for horizontally spraying urea solution to the right is arranged at the lower left side of the secondary combustion chamber, the spraying direction of the first SNCR spray gun is along the horizontal center line of the bottom of the U-shaped inner cavity, and a second SNCR spray gun for vertically spraying urea solution upward is arranged at the lower right side of the secondary combustion chamber, the spraying direction of the second SNCR spray gun is along the vertical center line of the right side of the U-shaped inner cavity.

[0006] A first support is arranged at the bottom of the secondary combustion chamber, a refractory castable layer is arranged on the inner wall of the inner cavity of the secondary combustion chamber, a rock wool insulation layer is wrapped outside the secondary combustion chamber, a dust falling pipe is arranged at the middle position of the U-shaped structure at the bottom of the secondary combustion chamber, and a first valve is arranged at the lower end of the dust falling pipe.

[0007] The waste heat boiler comprises a second support, a furnace formed by an outer membrane water cooling wall, an internal membrane water cooling wall arranged in the middle of the furnace, the upper end and the lower end of the internal membrane water cooling wall being connected with the top and the bottom of the outer membrane water cooling wall respectively, the internal membrane water cooling wall separating the furnace into a left heat exchange chamber and a right heat exchange chamber, the lower part of the internal membrane water cooling wall being provided with a through hole for connecting the left heat exchange chamber and the right heat exchange chamber, the flue gas inlet being arranged on the upper left side of the outer membrane water cooling wall, the flue gas outlet being arranged on the upper right side of the outer membrane water cooling wall, a drum being arranged above the outer membrane water cooling wall, the drum being connected with the top of the outer membrane water cooling wall through a steam rising pipe and a cold water falling pipe, and the flue gas inlet, the left heat exchange chamber, the through hole, the right heat exchange chamber and the flue gas outlet forming a through baffle heat exchange channel.

[0008] The center line of the drum is horizontally arranged along the left-right direction, the left end of the drum is provided with a liquid level meter, the lower part of the right end of the drum is provided with a blowdown pipe joint, the top of the drum is provided with a steam outlet, a safety valve interface, a safety valve standby interface and a pressure gauge interface, the upper part of the front side of the drum is provided with a water supply pipe joint, the inside of the drum is provided with a water supply distribution pipe connected with the inner port of the water supply pipe joint, the inside of the drum is provided with a water supply distribution hole plate located below the water supply distribution pipe, and the inside of the drum is provided with a steam-water separator connected with the steam outlet.

[0009] The bottom of each of the left heat exchange chamber and the right heat exchange chamber is provided with a dust hopper, and the lower end of each dust hopper is provided with a second valve.

[0010] Compared with the prior art, the utility model has the following technical effects:

[0011] 1) The steam rising pipe is adjacent to the steam outlet (the rising steam is easier to enter into the drum), the cold water falling pipe is far away from the steam outlet. The steam-water separator is arranged on the top of the drum, the steam and the water are separated by the hole plate and the baffle, the water content of the high-temperature steam is not more than 3%, and the steam quality is ensured. The water supply distribution pipe and the water supply distribution hole plate can ensure that the water supply is uniformly distributed into the drum, so that the temperature deviation of each part in the drum is within 3℃, and the steam production efficiency is improved.

[0012] 2) The secondary combustion chamber can improve the flue gas temperature, fully burn the combustible gas such as H2 and CO in the flue gas, reduce the NOx in the flue gas into N2 and CO2 harmless gas, and decompose dioxin. The U-shaped inner cavity structure of the secondary combustion chamber has the following advantages: it is beneficial to the balance of flue gas temperature; it can ensure that the flue gas and the urea solution are fully mixed, improve the SNCR denitration efficiency, and fully decompose the dioxin and combustible gas in the flue gas; the U-shaped inner cavity wall is not easy to accumulate dust, and the bottom is provided with a dust falling pipe to facilitate the discharge of the sediment.

[0013] 3) flue gas into the waste heat utilization boiler heat exchange, flue gas heat utilization, the high temperature steam generated for the following fly ash in the flue gas desalination process, while the temperature of the flue gas is reduced after passing through the waste heat utilization boiler, providing preliminary cooling for the subsequent desulfurization and desalination spray.

[0014] 4) the hearth of the waste heat utilization boiler adopts a vertical structure, which is not easy to accumulate dust and salt, and is convenient to overhaul and clean after long time operation; the external membrane type water cooling wall structure is compact, saves steel, and reduces a large amount of sealing castable and heat preservation material; the bottom is provided with a dust hopper, which is convenient for cleaning the accumulated dust after long time operation.

[0015] In summary, the principle of the utility model is scientific, the structure is compact, the flue gas discharged from the plasma furnace is first heated, the combustible gas and dioxin inside are treated, denitration is carried out, then the high temperature flue gas is heat exchanged and cooled by the waste heat utilization boiler, which lays a foundation for the subsequent desulfurization and desalination spray process, and the high temperature steam generated is used for the fly ash desalination process in the flue gas, which achieves multiple purposes at a time. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of the utility model;

[0017] Figure 2 is Figure 1 an enlarged view of the middle drum. DETAILED DESCRIPTION

[0018] The embodiment of the utility model will be further described in detail in combination with the drawings and examples.

[0019] As Figure 1 and Figure 2 shown, the utility model's plasma furnace flue gas's two combustion chambers and waste heat boiler combination pretreatment system, including two combustion chambers 1 and waste heat utilization boiler;Two combustion chambers 1's inner chamber is U-shaped structure, two combustion chambers 1 left side upper end is equipped with the air inlet elbow joint 2, two combustion chambers 1 right side upper end is equipped with the air outlet elbow joint 3, the air outlet elbow joint 3 right end is connected with the waste heat utilization boiler left side's flue gas import 4, the waste heat utilization boiler inside is equipped with the baffle heat exchange channel, the waste heat utilization boiler right side is equipped with the flue gas export 5.

[0020] Two combustion chambers 1 left side upper part is equipped with the burner installation mouth 6, and the burner installation mouth 6 is equipped with the burner 7 that burns natural gas, and two combustion chambers 1 left side lower part is equipped with the first SNCR spray gun 8 that sprays urea solution horizontally to right, and the injection direction of the first SNCR spray gun 8 follows the horizontal center line of the bottom of the U-shaped inner chamber, and two combustion chambers 1 right side lower part is equipped with the second SNCR spray gun 9 that sprays urea solution vertically upward, and the injection direction of the second SNCR spray gun 9 follows the vertical center line of the right side of the U-shaped inner chamber.

[0021] The first support 10 is arranged at the bottom of the secondary combustion chamber 1, a refractory castable layer is arranged on the inner wall of the inner cavity of the secondary combustion chamber 1, the secondary combustion chamber 1 is wrapped with a rock wool heat preservation layer, and the bottom of the secondary combustion chamber 1 is arranged with a dust falling pipe 11 at the middle position of the U-shaped structure, and the lower end of the dust falling pipe 11 is arranged with a first valve.

[0022] The waste heat utilization boiler comprises a second support 12, a furnace chamber surrounded by an outer membrane water cooling wall 13 is arranged on the second support 12, an inner membrane water cooling wall 14 is arranged at the middle part of the furnace chamber, the upper end and the lower end of the inner membrane water cooling wall 14 are connected with the top and the bottom of the outer membrane water cooling wall respectively, the inner membrane water cooling wall 14 divides the furnace chamber into a left heat exchange cavity 15 and a right heat exchange cavity 16, the lower part of the inner membrane water cooling wall 14 is arranged with a through hole 17 communicating the left heat exchange cavity 15 and the right heat exchange cavity 16, the smoke inlet 4 is arranged on the left upper part of the outer membrane water cooling wall 13, the smoke outlet 5 is arranged on the right upper part of the outer membrane water cooling wall 13, a boiler drum 18 is arranged above the outer membrane water cooling wall 13, the boiler drum 18 is connected with the top of the outer membrane water cooling wall 13 through a steam rising pipe 19 and a cold water flowing pipe 20, and the smoke inlet 4, the left heat exchange cavity 15, the through hole 17, the right heat exchange cavity 16 and the smoke outlet 5 form a through baffle heat exchange channel.

[0023] The center line of the boiler drum 18 is horizontally arranged along the left-right direction, the left end of the boiler drum 18 is arranged with a liquid level meter 21, the lower part of the right end of the boiler drum 18 is arranged with a blowdown pipe joint 22, the top of the boiler drum 18 is arranged with a steam outlet 23, a safety valve interface 24, a safety valve standby interface 25 and a pressure gauge interface 26, the upper part of the front side of the boiler drum 18 is arranged with a water supply pipe joint 27, the inside of the boiler drum 18 is arranged with a water supply distribution pipe 28 connected with the inner port of the water supply pipe joint 27, the inside of the boiler drum 18 is arranged with a water supply distribution hole plate 29 located below the water supply distribution pipe 28, and the upper part of the inside of the boiler drum 18 is arranged with a steam-water separator 30 connected with the steam outlet 23.

[0024] The bottom of the left heat exchange cavity 15 and the bottom of the right heat exchange cavity 16 are both arranged with a dust falling hopper 31, and the lower end of the dust falling hopper 31 is arranged with a second valve.

[0025] The working process of the utility model is: the flue gas generated by burning garbage in the plasma furnace is connected with the air inlet elbow joint 2 through the exhaust pipe, the flue gas enters the inner cavity of the secondary combustion chamber 1, the temperature in the secondary combustion chamber 1 is increased to 1100 DEG C by the flame sprayed by the burner 7, the combustible gas and dioxin in the flue gas are burned and decomposed under high temperature, when the flue gas passes through the lower part of the U-shaped inner cavity, the first SNCR spray gun 8 sprays atomized urea to the right, the second SNCR spray gun 9 sprays atomized urea upward, the urea fully reacts with NOx in the flue gas as follows: 4CO (NH2) 2 + 5NO + 302 to 4CO2 + 4H2O + 5N2, thereby removing NOx in the flue gas, achieving the purpose of synchronous denitration, the dust in the flue gas falls into the ash drop pipe 11 and is temporarily stored, the pretreated flue gas enters the waste heat utilization boiler, the high-temperature flue gas passes through the flue gas inlet 4, the left heat exchange cavity 15, the through hole 17, the right heat exchange cavity 16 and the flue gas outlet 5 in sequence to form a through baffle heat exchange channel, the water in the external membrane type water cooling wall 13 and the internal membrane type water cooling wall 14 is heated, the heated water forms water vapor which enters the boiler drum 18 through the steam rising pipe 19, after the water vapor is separated from the water in the steam-water separator 30 into the boiler drum 18, the high-temperature steam containing basically no water is discharged through the steam outlet 23 and is used in the flue gas subsequent desalination system MVR evaporator to save energy. Figure 1 The middle single arrow points to the flue gas flow direction. Figure 2 The middle single arrow is the water flow direction, and the double arrow is the steam flow direction.

[0026] It is necessary to emphasize that the burner 7, the first SNCR spray gun 8, the second SNCR spray gun 9, the liquid level meter 21, the steam-water separator 30 and the valve in the utility model are all prior art and can be purchased in the market, and the specific structure and working principle will not be repeated.

[0027] The above embodiments illustrate the basic principle and characteristics of the utility model, but the above only illustrates the relatively optimal embodiment of the utility model, and is not limited by the described embodiments. Ordinary skilled in the art can make many forms of deformation and improvement under the inspiration of the patent without departing from the purpose of the utility model and the scope protected by the claims, and these all belong to the protection scope of the utility model. Therefore, the utility model patent and the protection scope should be subject to the appended claims.

Claims

1. A combined two-burner and waste heat boiler pretreatment system for flue gases of a plasma furnace, characterized in that: The application relates to a secondary combustion chamber and a waste heat utilization boiler; the inner cavity of the secondary combustion chamber is in a U-shaped structure, an air inlet elbow joint is arranged at the upper left end of the secondary combustion chamber, an air outlet elbow joint is arranged at the upper right end of the secondary combustion chamber, the right end of the air outlet elbow joint is connected with a flue gas inlet on the left side of the waste heat utilization boiler, a baffle heat exchange channel is arranged in the waste heat utilization boiler, and a flue gas outlet is arranged on the right side of the waste heat utilization boiler.

2. The two-burner and waste heat boiler combined pretreatment system of flue gas of a plasma furnace according to claim 1, characterized in that: A burner for burning natural gas is arranged in a burner mounting hole arranged at the upper left side of the secondary combustion chamber, a first SNCR spray gun for horizontally spraying urea solution to the right is arranged at the lower left side of the secondary combustion chamber, the spraying direction of the first SNCR spray gun is along the horizontal center line of the bottom of the U-shaped cavity, and a second SNCR spray gun for vertically spraying urea solution upwards is arranged at the lower right side of the secondary combustion chamber, the spraying direction of the second SNCR spray gun is along the vertical center line of the right side of the U-shaped cavity.

3. The two-burner and waste heat boiler combined pretreatment system of flue gas of a plasma furnace according to claim 2, characterized in that: A first support is arranged at the bottom of the secondary combustion chamber, a refractory castable layer is arranged on the inner wall of the cavity of the secondary combustion chamber, a rock wool heat preservation layer is arranged outside the secondary combustion chamber, and a dust falling pipe is arranged at the middle position of the U-shaped structure at the bottom of the secondary combustion chamber, and a first valve is arranged at the lower end of the dust falling pipe.

4. The two-burner and waste heat boiler combined pretreatment system of flue gas of plasma furnace according to claim 1, characterized in that: The waste heat utilization boiler comprises a second support, a furnace is formed by surrounding the second support with an external membrane type water cooling wall, an internal membrane type water cooling wall is arranged in the middle of the furnace, the upper end and the lower end of the internal membrane type water cooling wall are connected with the top and the bottom of the external membrane type water cooling wall respectively, the internal membrane type water cooling wall divides the furnace into a left heat exchange chamber and a right heat exchange chamber, a through hole is arranged at the lower part of the internal membrane type water cooling wall and communicates the left heat exchange chamber and the right heat exchange chamber, the flue gas inlet is arranged at the upper left side of the external membrane type water cooling wall, the flue gas outlet is arranged at the upper right side of the external membrane type water cooling wall, a boiler drum is arranged above the external membrane type water cooling wall, the boiler drum is connected with the top of the external membrane type water cooling wall through a steam rising pipe and a cold water flowing pipe, and the flue gas inlet, the left heat exchange chamber, the through hole, the right heat exchange chamber and the flue gas outlet form a through baffle heat exchange channel.

5. The two-burner and waste heat boiler combined pretreatment system of flue gas of a plasma furnace according to claim 4, characterized in that: The center line of the boiler drum is horizontally arranged along the left-right direction, a liquid level meter is arranged at the left end of the boiler drum, a blowdown pipe joint is arranged at the lower right end of the boiler drum, a steam outlet, a safety valve interface, a safety valve standby interface and a pressure gauge interface are arranged at the top of the boiler drum, a water supply pipe joint is arranged at the upper front side of the boiler drum, a water supply distribution pipe connected with the inner port of the water supply pipe joint is arranged in the boiler drum, a water supply distribution hole plate located below the water supply distribution pipe is arranged in the boiler drum, and a steam-water separator connected with the steam outlet is arranged in the upper part of the boiler drum.

6. The two-burner and waste heat boiler combined pretreatment system of flue gases of a plasma furnace according to claim 4 or 5, characterized in that: A dust falling hopper is arranged at the bottom of the left heat exchange chamber and the right heat exchange chamber, and a second valve is arranged at the lower end of the dust falling hopper.

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