Low-temperature denitration device and method for flue gas of lime kiln

Abstract

The application provides a lime kiln flue gas low-temperature SCR denitration device, which has small volume, small land occupation, low construction and operation cost and long stable working time. The device comprises an SCR reactor, a flue gas outlet of the SCR reactor is communicated with a chimney through an induced draft fan, and a flue gas inlet of the SCR reactor is communicated with a flue gas outlet of a bag-type dust collector through a denitration flue, characterized in that the device further comprises a combustion chamber, a double-fluid spray gun and a pipeline burner; the combustion chamber is arranged on the denitration flue between the SCR reactor and the bag-type dust collector; the pipeline burner and the double-fluid spray gun are installed in the combustion chamber; and a liquid inlet of the double-fluid spray gun is communicated with an ammonia water supply device. Meanwhile, the application also discloses a lime kiln flue gas low-temperature SCR denitration method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas denitration device, in particular to a lime kiln flue gas low-temperature SCR denitration device and method. BACKGROUND

[0002] The high-temperature flue gas generated by fuel combustion in the lime kiln is reduced to below 180℃ by a mechanical cooler, enters a bag-type dust collector for dust removal, and the flue gas discharged from the bag-type dust collector has the characteristics of low temperature (about 140℃), high sulfur content, high alkali metal content, large flue gas volume, and high moisture content, and needs to be treated by denitration before being discharged into the atmosphere through a chimney.

[0003] The selective catalytic reduction method (SCR) is the most widely used flue gas denitration method, and the SCR denitration technology refers to the direct conversion of nitrogen oxides in flue gas into water and nitrogen gas by using a reducing agent (such as ammonia, urea, and ammonia water) under the action of a denitration catalyst. Because the required flue gas temperature in the SCR denitration device is higher than the flue gas temperature discharged from the bag-type dust collector, an existing technology adds a heating device, such as a flue gas reheater GGH, between the bag-type dust collector and the SCR denitration device, and an ammonia water evaporator is also needed to atomize the ammonia water used as the reducing agent. The existing special heating device and ammonia water evaporator require a large area, and the equipment cost is high, which further leads to high overall process cost and large system resistance. SUMMARY

[0004] In order to solve the problems of large area and high cost of the existing equipment, the present application provides a lime kiln flue gas low-temperature SCR denitration device, which has a small overall volume, occupies a small area, and has relatively low construction and operation costs, and can work stably for a long time. The present application also discloses a lime kiln flue gas low-temperature SCR denitration method.

[0005] The technical solution of the present application is as follows: a lime kiln flue gas low-temperature SCR denitration device, which comprises an SCR reactor, a flue gas outlet of the SCR reactor is connected to a chimney through an induced draft fan, and a flue gas inlet of the SCR reactor is connected to a flue gas outlet of a bag-type dust collector through a denitration flue, characterized in that it further comprises a combustion chamber, a double-fluid spray gun, and a pipeline burner.

[0006] The combustion chamber is arranged on the denitration flue between the SCR reactor and the bag-type dust collector.

[0007] The pipeline burner and the double-fluid spray gun are installed in the combustion chamber, and a liquid inlet of the double-fluid spray gun is connected to an ammonia water supply device.

[0008] Further features are as follows:

[0009] The pipeline burner is connected to a combustion air fan.

[0010] The SCR reactor is provided with a flue gas uniform distribution device and a catalyst; the catalyst is a low-temperature catalyst resistant to sulfur and alkali metals;

[0011] The double-fluid spray gun and the combustion chamber are connected by a flange.

[0012] A low-temperature SCR denitration method for lime kiln flue gas, characterized in that it comprises the following steps:

[0013] S1: arranging a pipeline burner and a double-fluid spray gun through a combustion chamber on the denitration flue between the SCR reactor and the bag-type dust collector;

[0014] S2: heating the flue gas in the denitration flue to a preset temperature by the pipeline burner, and atomizing ammonia water sprayed by the double-fluid spray gun into small droplets by using the temperature of the high-temperature flue gas in the combustion chamber;

[0015] S3: sending the heated flue gas and the atomized ammonia water into the SCR reactor at the same time;

[0016] S4: the flue gas and the atomized ammonia water perform a denitration reaction under the action of the catalyst in the SCR reactor.

[0017] It is further characterized in that:

[0018] The preset temperature is 160-180℃;

[0019] In step S2, the ammonia water sprayed by the double-fluid spray gun is ammonia water with a concentration of 20%, and the size of the atomized ammonia water droplets is less than or equal to 60μm.

[0020] The low-temperature SCR denitration device for lime kiln flue gas provided by the application uses a pipeline burner and a combustion chamber to heat the flue gas, which has a smaller footprint, lower investment, and lower system resistance compared with the existing GGH device for heating; the combustion chamber is used to vaporize ammonia water, which saves an ammonia water evaporator and further reduces the required footprint; the technical solution of the application has a small size, a small footprint, and a relatively low construction and operation cost, and can ensure stable operation for a long time. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 FIG. 1 is a structural schematic diagram of a low-temperature SCR flue gas denitration device. DETAILED DESCRIPTION

[0022] As Figure 1As shown, the low-temperature SCR denitration device for lime kiln flue gas of the present application comprises: an SCR reactor 3, the flue gas outlet of the SCR reactor 3 is communicated with a chimney 13 through an induced draft fan 14, the flue gas inlet of the SCR reactor 3 is communicated with the flue gas outlet of a bag filter 1 through a denitration flue 2, and the flue gas pipeline 12 of the bag filter 1 is connected with a solid waste incineration device (not marked in the figure).

[0023] A combustion chamber 6 is arranged on the denitration flue 2 between the SCR reactor 3 and the bag filter 1; a pipeline burner 8 and a double-fluid spray gun 9 are installed in the combustion chamber 6; the liquid inlet 10 of the double-fluid spray gun 9 is communicated with an ammonia water supply device (not shown in the figure), and the gas inlet 11 is communicated with a compressed air device (not shown in the figure); the pipeline burner 8 is communicated with a combustion air fan 7; a flue gas uniform distribution device 4 and a catalyst 5 are arranged in the SCR reactor 3; in this embodiment, the catalyst 5 is a low-temperature catalyst resistant to sulfur and alkali metals, and the flue gas uniform distribution device 4 uses a guide plate and a flue gas uniform distribution plate; the double-fluid spray gun 9 and the combustion chamber 6 are flange-connected.

[0024] The catalyst used in the present application is a low-temperature catalyst resistant to sulfur and alkali metals, which can maintain high denitration activity at 160℃, 1000mg / m 3 The ion-exchange coordination mechanism has good alkali resistance, and the low-temperature catalyst does not need to be frequently replaced due to poisoning of alkali metals and sulfur and ammonium, which not only ensures stable operation effect, but also reduces operation cost; the temperature rising device of the technical scheme of the present application does not need to use a GGH, the resistance of the denitration system can be reduced by about 500Pa, thereby reducing the investment of the induced draft fan, and further reducing the system operation cost.

[0025] A low-temperature SCR denitration method for lime kiln flue gas, characterized in that it comprises the following steps:

[0026] S1: The pipeline burner 8 and the double-fluid spray gun 9 are arranged on the denitration flue 2 between the SCR reactor 3 and the bag filter 1 through the combustion chamber 6;

[0027] S2: After the reaction starts, the flue gas at the flue gas outlet of the bag filter 1 enters the denitration flue 2;

[0028] The combustion air fan 7 and the pipeline burner 8 are started to heat the flue gas in the denitration flue 2 to a preset temperature, and the preset temperature is set in advance according to the temperature required by the catalytic reaction in the SCR reactor 3; the low-temperature catalyst in this embodiment reacts at a preset temperature in the range of 160℃ to 180℃;

[0029] Simultaneously, after being combusted by the burner 8, the temperature generated in the combustion chamber 6 atomizes the ammonia water sprayed by the double-fluid spray gun 9 into small droplets, the ammonia water sprayed by the double-fluid spray gun 9 is ammonia water with a concentration of 20%; the size of the atomized ammonia water droplets is less than or equal to 60 μm;

[0030] S3: the heated flue gas to be treated and the atomized ammonia water are simultaneously sent into the SCR reactor 3 through the denitration flue 2;

[0031] S4: the flue gas to be treated and the atomized ammonia water perform a denitration reaction under the action of the catalyst 5 in the SCR reactor 3; the tail gas generated after the flue gas to be treated performs the denitration reaction is discharged into the chimney 13 through the induced draft fan 14.

[0032] After the technical scheme of the present application is used, the flue gas at the outlet of the dust collector at 140℃ is raised to 160℃ required by the low-temperature denitration by using the pipeline burner, compared with the GGH in the prior art, the present application has a small occupation area and low investment; the technical scheme of the present application atomizes the ammonia water by using the high-temperature flue gas in the combustion chamber 6 and the double-fluid spray gun 9 to generate a reducing agent for the denitration reaction, without the need of separately setting an ammonia water evaporator, thereby further reducing the occupation area of the device and the system construction and operation investment cost; after the flue gas to be treated and the atomized ammonia water are sent into the SCR reactor 3 through the denitration flue 2, the flue gas to be treated is first guided by the flue gas uniform distribution device 4, thereby ensuring that the flue gas to be treated can uniformly react under the action of the catalyst in the SCR reactor 3.

Claims

1. A low-temperature SCR denitrification device for lime kiln flue gas, comprising: The SCR reactor, wherein the flue gas outlet of the SCR reactor is connected to a chimney via an induced draft fan, and the flue gas inlet of the SCR reactor is connected to the flue gas outlet of a bag filter via a denitrification flue, is characterized in that it further includes: a combustion chamber, a dual-fluid spray gun, and a pipeline burner. The combustion chamber is located on the denitrification flue between the SCR reactor and the bag filter. The pipe burner and the dual-fluid spray gun are installed in the combustion chamber; the liquid inlet of the dual-fluid spray gun is connected to an ammonia supply device; the gas inlet of the dual-fluid spray gun is connected to a compressed air device. The flue gas to be treated is heated by a pipe burner and a combustion chamber. At the same time, the temperature generated in the combustion chamber after combustion is used to atomize the ammonia water sprayed by the dual-fluid spray gun into small droplets. The high-temperature flue gas in the combustion chamber is used to vaporize the ammonia water, saving the ammonia water evaporator. The heated flue gas to be treated and the atomized ammonia water are simultaneously sent to the SCR reactor through the denitrification flue. The pipeline burner is connected to the combustion-supporting fan; The SCR reactor is equipped with a flue gas uniform distribution device and a catalyst; the catalyst is a low-temperature catalyst resistant to sulfur and alkali metals.

2. The low-temperature SCR denitrification device for lime kiln flue gas according to claim 1, characterized in that: The dual-fluid spray gun and the combustion chamber are connected by a flange.

3. A method for low-temperature SCR denitrification of lime kiln flue gas based on the low-temperature SCR denitrification device of claim 1, characterized in that, It includes the following steps: S1: Start the combustion fan and the pipeline burner. The pipeline burner heats the flue gas to be treated in the denitrification flue to a preset temperature. At the same time, the high temperature of the flue gas in the combustion chamber atomizes the ammonia water sprayed by the dual-fluid spray gun into small droplets. The preset temperature is 160℃~180℃. The high temperature of the flue gas in the combustion chamber vaporizes the ammonia water, saving the ammonia water evaporator. The ammonia water sprayed by the dual-fluid spray gun is 20% concentration ammonia water; the atomized ammonia water droplet size is less than or equal to 60μm; S2: The heated flue gas to be treated and the atomized ammonia water are simultaneously sent to the SCR reactor; S3: The flue gas to be treated and the atomized ammonia water undergo a denitrification reaction under the action of a catalyst in the SCR reactor; the catalyst is a low-temperature catalyst resistant to sulfur and alkali metals.

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