Catalyst method desulfurization and denitrification system with ammonia gas inhibition dioxin structure

Abstract

The catalyst method desulfurization and denitrification system with the ammonia gas dioxin inhibition structure comprises a catalytic reaction tank, the upper part of the catalytic reaction tank is connected and matched with an ammonia gas evaporator, a hot-air blower and a chimney, and the joint of the ammonia gas evaporator and a flue gas inlet pipe is positioned in front of the joint of the hot-air blower and the flue gas inlet pipe. One gas outlet of the ammonia gas evaporator is connected with an ammonia gas distributor through a pipeline, the ammonia gas distributor is divided into pipelines with different gas output, the pipelines are connected with a catalyst layer ammonia gas supplementing pipe, extend into the catalyst layer and are provided with gas outlet holes, and the bottom of the catalytic reaction tank is connected with a waste heat recovery heat exchanger; a smoke outlet pipe box of the waste heat recovery heat exchanger is communicated with a saturated sodium chloride solution pool, and a top outlet of the saturated sodium chloride solution pool is connected with a chimney. The device has the beneficial effects that the ammonia gas is introduced in advance before the flue gas is heated, the flue gas is prevented from being heated to generate dioxin, the ammonia gas supplementing pipe enables the flue gas to be inhibited by the ammonia gas, the waste heat recovery heat exchanger is rapidly cooled, and the dioxin is inhibited in the whole process.

Description

Technical Field

[0001] This utility model relates to desulfurization and denitrification technology in sintering ironmaking, and specifically to structural improvements in catalyst-based desulfurization and denitrification systems. Background Technology

[0002] The sintering process in the steel industry is a major source of dioxins. While catalytic desulfurization and denitrification are highly effective, the catalyst requires a temperature of 280-300°C to achieve optimal reaction. When the sintering flue gas reaches the desulfurization and denitrification system, its temperature is below 100°C, requiring heating to 280°C. However, this high temperature promotes dioxin formation. Ammonia, which inhibits dioxin formation, is supplied to the desulfurization and denitrification system via a pipeline and gas outlet from an ammonia evaporator. Heating the desulfurization and denitrification system requires a hot air furnace or electric hot air blower. The flue gas is heated upon arrival, and this high temperature leads to dioxin formation. At this point, the flue gas has not yet reached the catalyst layer. Even after passing through the catalyst layer, the flue gas temperature remains above 270°C, and the ammonia has been consumed, resulting in further dioxin formation. Therefore, catalytic desulfurization and denitrification will produce dioxins. To meet emission standards, dioxin removal devices need to be added after the desulfurization and denitrification system, such as activated carbon adsorption and decomposition by decomposers, which will increase the number of treatment steps and the cost. Since ammonia is used in catalytic desulfurization and denitrification, the inventors improved the flue gas desulfurization and denitrification system to make full use of ammonia to suppress dioxin production. Utility Model Content

[0003] The purpose of this invention is to propose a catalyst-based desulfurization and denitrification system that uses ammonia to suppress dioxins.

[0004] The technical solution of this utility model is as follows: a catalyst-based desulfurization and denitrification system with an ammonia-inhibiting dioxin structure, comprising a catalytic reaction tank, with an ammonia evaporator, a hot air blower, and a chimney connected to the upper part of the catalytic reaction tank. The connection between the ammonia evaporator and the flue gas inlet pipe is located before the connection between the hot air blower and the flue gas inlet pipe. The ammonia evaporator has two or more gas outlets, one of which is connected to an ammonia distributor via a pipe. The ammonia distributor branches out pipes with different gas outputs, which are connected to a catalyst layer ammonia replenishment pipe. The catalyst layer ammonia replenishment pipe extends into the catalyst layer inside the catalytic reaction tank and has uniformly arranged gas outlet holes. A waste heat recovery heat exchanger is connected to the bottom of the catalytic reaction tank. The waste heat recovery heat exchanger is used to rapidly cool the flue gas after desulfurization and denitrification. The flue gas outlet of the waste heat recovery heat exchanger is connected to a saturated sodium chloride solution tank, and the top outlet of the saturated sodium chloride solution tank is connected to the chimney.

[0005] Furthermore, a gas distributor is installed around the flue gas inlet inside the catalytic reaction tank. The gas distributor is a gas flow structure with pores.

[0006] Furthermore, the saturated sodium chloride solution tank is equipped with an aeration disc, which is a circular disc with a circular array of small holes.

[0007] Preferably, the waste heat recovery heat exchanger is a plate heat exchanger.

[0008] Preferably, the catalyst layer has three layers.

[0009] The beneficial effects of this invention are as follows: By introducing ammonia gas before heating the flue gas, the generation of dioxins from the flue gas temperature rise is suppressed. At the same time, an ammonia gas replenishment pipe is set in the catalyst layer to replenish the consumed ammonia gas in a timely manner, so that the high-temperature flue gas is always suppressed by ammonia gas. In the later stage, the waste heat recovery heat exchanger is used to rapidly cool down the flue gas, destroying the temperature conditions for dioxin generation. Thus, dioxin generation is suppressed throughout the entire desulfurization and denitrification process. While providing the system with the necessary ammonia gas, the diffusion of ammonia gas can be fully utilized to suppress dioxin generation. The investment in equipment is not significantly increased, thus reducing costs and increasing efficiency. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the composition of this utility model;

[0011] In the diagram, 1-flue gas inlet pipe, 2-ammonia evaporator, 3-hot air blower, 4-ammonia distributor, 5-ammonia replenishment pipe for catalyst layer, 6-catalyst layer, 7-catalytic reaction tank, 8-waste heat recovery heat exchanger, 9-saturated sodium chloride solution pool, 10-chimney, 11-gas distributor, 12-aeration disc. Detailed Implementation

[0012] like Figure 1 As shown, the catalyst-based desulfurization and denitrification system with an ammonia-based dioxin-suppressing structure includes a catalytic reactor 7. The upper part of the catalytic reactor 7 is connected to a flue gas inlet pipe 1, and it is equipped with an ammonia evaporator 2, a hot air blower 3, and a chimney 10. The connection between the ammonia evaporator 2 and the flue gas inlet pipe 1 is located before the connection between the hot air blower 3 and the flue gas inlet pipe 1. The ammonia evaporator 2 has two or more outlets. One outlet is connected to an ammonia distributor 4 via a pipe. The ammonia distributor 4 branches out pipelines with different gas outputs, and the gas flow rate is controlled by a gas flow valve on the pipeline. The pipeline connects to a catalyst layer ammonia supply pipe 5, which extends into the catalyst layer 6 inside the catalytic reactor 7 and has uniformly arranged gas outlet holes. The ammonia output of the catalyst layer ammonia supply pipe 5 installed at different heights of the catalyst layer 6 is not equal, nor does it simply increase or decrease from top to bottom. Instead, it appropriately supplies supplementary ammonia according to the concentration at which ammonia can suppress dioxins. The bottom of the catalytic reaction tank 7 is connected to a waste heat recovery heat exchanger 8, which is used to rapidly cool down the flue gas after desulfurization and denitrification. The flue gas outlet of the waste heat recovery heat exchanger 8 is connected to a saturated sodium chloride solution tank 9, and the top outlet of the saturated sodium chloride solution tank 9 is connected to a chimney 10.

[0013] To improve the dispersion speed of flue gas after it enters the catalytic reactor 7, a gas distributor 11 is installed around the internal flue gas inlet. The gas distributor 11 is a porous gas flow structure that blocks and diffuses the flue gas, allowing it to spread to the inner wall of the catalytic reactor and preventing it from concentrating and flowing downwards in the middle. The catalyst layer 6 can be designed as three layers: a desulfurization catalyst, a denitrification catalyst, and a mixed catalyst. The structure of the catalyst layer (mainly including mesh plates, mesh grooves, etc.) and the type of catalyst are existing technologies, and the catalyst is granular.

[0014] The saturated sodium chloride solution tank 9 is equipped with an aeration disc 12, which is a circular disc with a circular array of small holes. The aeration disc 12 causes the treated flue gas to flow out in multiple thin streams, increasing the contact area with the sodium chloride solution. If the aeration disc 12 causes poor exhaust, a fan can be added to the connecting pipe between the saturated sodium chloride solution tank 9 and the chimney 10 to increase the air pressure at the end of the flue gas flow.

[0015] The waste heat recovery heat exchanger 8 is preferably a plate heat exchanger, which has a large contact area with the external circulating liquid, helping to cool the flue gas quickly down to 120 degrees Celsius, away from the temperature range where dioxins are generated.

[0016] The device allows ammonia gas to enter the flue gas inlet pipe 1 before heating the hot air. The hot air from the hot air blower 3 heats the mixture of ammonia and flue gas, reducing the probability of dioxin formation due to increased flue gas temperature. As the flue gas passes through the catalyst layer 6, the consumed ammonia gas is replenished through the catalyst layer ammonia replenishment pipe 5, maintaining the partial pressure of ammonia in the flue gas at a level that inhibits dioxin formation. Later, rapid heat exchange cooling of the desulfurized and denitrified flue gas disrupts the temperature conditions necessary for dioxin formation. Excess ammonia gas is absorbed by a saturated sodium chloride solution.

Claims

1. A catalyst method desulfurization and denitrification system with dioxin structure inhibited by ammonia gas, comprising a catalytic reaction tank (7), a flue gas inlet pipe (1) connected to the upper part of the catalytic reaction tank (7), and an ammonia gas evaporator (2), a hot air blower (3), and a chimney (10) matched therewith, characterized in that: The connection of the ammonia vaporizer (2) and the flue gas inlet pipe (1) is located before the connection of the hot air fan (3) and the flue gas inlet pipe (1), the ammonia vaporizer (2) is provided with two or more gas outlets, one gas outlet is connected with an ammonia gas distributor (4) through a pipeline, the ammonia gas distributor (4) divides pipelines with different gas outlet amounts, the pipelines are connected with catalyst layer ammonia supplement pipes (5), the catalyst layer ammonia supplement pipes (5) extend into the catalyst layer (6) inside the catalytic reaction tank (7) and are provided with uniformly arranged gas outlets, the bottom of the catalytic reaction tank (7) is connected with a waste heat recovery heat exchanger (8), the waste heat recovery heat exchanger (8) is used for rapidly cooling and cooling the flue gas after desulfurization and denitrification, the waste heat recovery heat exchanger (8) is connected with a saturated sodium chloride solution pool (9) through a flue gas outlet pipe box, and the top outlet of the saturated sodium chloride solution pool (9) is connected with a chimney (10). ​ 2. The catalyst method of desulfurization and denitrification system with ammonia gas inhibiting dioxin structure according to claim 1, characterized in that: A gas distributor (11) is arranged around the flue gas inlet of the catalytic reaction tank (7), and the gas distributor (11) is a gas flow-through structure with pores.

3. The catalyst method of desulfurization and denitrification system with ammonia gas inhibiting dioxin structure according to claim 1, characterized in that: The saturated sodium chloride solution pool (9) is provided with an aeration disc (12), and the aeration disc (12) is a circular disc with a structure of circularly arrayed small holes.

4. The catalyst method of desulfurization and denitrification system with ammonia gas inhibiting dioxin structure according to claim 1, characterized in that: The waste heat recovery heat exchanger (8) is a plate heat exchanger.

5. The catalyst method of desulfurization and denitrification system with ammonia gas inhibiting dioxin structure according to claim 1, characterized in that: The catalyst layer (6) is provided with three layers.

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