CN103821598A - Marine diesel engine exhaust selective catalytic reduction denitrification system - Google Patents

Abstract

Marine diesel engine tail gas selective catalytic reduction deNOx systems, including arranging selective catalytic reduction in marine diesel engine exhaust-gas discharge pipe in and removing nitration catalyst ware, atomizer and helical blade blender, the atomizer includes atomizing nozzle, atomizing body and nozzle cap, establishes compressed air room, mixing hole and liquid hole in the atomizing nozzle, and the helical blade blender comprises the helical blade who fixes on the drum inside wall, and the helical blade does not reach drum central part, makes drum central part form through hole. The invention has the advantages that the ammonia water or the urea water is atomized and fully mixed with the tail gas, and meanwhile, the required oxygen is provided for the denitration reaction, and the denitration efficiency is improved.

Description

Marine diesel engine exhaust selective catalytic reduction denitrification system

technical field

The invention belongs to the technical field of marine diesel engines, and in particular relates to a device for treating nitrogen oxides in exhaust gas of marine diesel engines by using a selective catalytic reduction denitrification system.

Background technique

The tail gas emitted by marine diesel engines contains a large amount of nitrogen oxides. Existing marine diesel engine tail gas is discharged without denitrification treatment, so it causes certain pollution to the environment. Should be treated before discharge. In the prior art, some studies have proposed to perform selective catalytic reduction (SCR for short) denitrification treatment on the tail gas of marine diesel engines. But no practical application has been seen yet. The selective catalytic reduction reaction of marine diesel engine exhaust requires oxygen to participate, but the oxygen content in marine diesel engine exhaust is low, and the selective catalytic reduction and denitrification reaction is directly carried out. Due to insufficient oxygen, the reaction will not be complete.

Contents of the invention

The purpose of the present invention is to provide a selective catalytic reduction denitrification system for marine diesel engine tail gas, so that the marine diesel engine tail gas can be fully mixed with atomized ammonia or urea water before the denitrification reaction, and at the same time, the oxygen content of the mixed gas can be increased.

The technical solution of the present invention is: a marine diesel engine tail gas selective catalytic reduction denitrification system, including a selective catalytic reduction denitrification catalyst placed in the marine diesel engine tail gas exhaust pipe, characterized in that: the marine diesel engine tail gas selective catalytic reduction denitrification system is also It includes an atomizer and a spiral blade mixer built between the selective catalytic reduction denitrification catalyst and the exhaust gas inlet in the exhaust gas discharge pipe, the atomizer includes an atomization nozzle, an atomization body and a nozzle cap, and the atomization The main body is a double-layer sleeve composed of an inner tube and an outer tube. The atomizing nozzle is a cone nozzle, and a compressed air chamber connected to the bottom surface of the cone is provided inside the cone. A mixing hole is provided on the front side wall of the cone. The inner end of the mixing hole communicates with the compressed air chamber, the outer end is open, and there is a liquid hole in the side wall of the cone. The rear end of the liquid hole is connected with the bottom surface of the cone, and the front end is connected with the mixing hole. The nozzle cap is sealed and connected, wherein the compressed air chamber of the cone is connected to the front end of the inner tube of the atomizing body, the liquid hole in the side wall of the cone is connected to the front end of the outer tube of the atomizing body, and the inner tube and the outer tube of the atomizing body are sealed. The rear end of the inner tube of the atomization body is connected to the compressed air source, and the rear end of the outer tube of the atomization body is connected to the reducing agent source; the spiral blade mixer is placed between the selective catalytic reduction denitration catalyst and the atomizer, The helical blade mixer is composed of helical blades fixed on the inner wall of the cylinder. The helical blades do not reach the center of the cylinder, so that the center of the cylinder forms a through hole.

The marine diesel engine tail gas selective catalytic reduction denitrification system of the present invention is characterized in that: the mixing holes of the atomizing nozzle have an even number of 4 to 10, which are symmetrically distributed along the front part of the cone, and the mixing holes between the two symmetrical mixing holes The included angle is 120°, and the liquid holes have an even number of 4 to 10, which are symmetrically distributed along the cone, and the included angle between two symmetrical liquid holes is 30°.

The marine diesel engine tail gas selective catalytic reduction denitrification system of the present invention is characterized in that: the diameter of the mixing hole of the atomizing nozzle is 1-5mm, and the diameter of the liquid hole is 0.6-2mm.

The marine diesel engine tail gas selective catalytic reduction denitrification system of the present invention is characterized in that: the helical angle of the helical blade of the mixer is between 45 degrees and 60 degrees.

The marine diesel engine tail gas selective catalytic reduction denitrification system of the present invention is characterized in that: the reducing agent is ammonia water or urea water.

The principle of the present invention is: in the selective catalytic reduction denitrification system, the mixing degree of ammonia water or urea water and tail gas is the decisive factor of denitrification efficiency. The higher the degree of atomization of ammonia water or urea water is, the higher the degree of mixing with tail gas is. The efficiency will be higher; at the same time, the selective catalytic reduction denitrification reaction requires oxygen to participate. The atomizer of the present invention uses compressed air to atomize the reducing agent (ammonia water or urea water), so that the reducing agent and the tail gas are mixed for the first time. At the same time, the compressed air also increases the oxygen content in the tail gas, effectively improving the Denitrification efficiency, the spiral blade mixer performs a second mixing of the mixed gas of the exhaust gas and the reducing agent to make the mixing more thorough.

The beneficial effect of the invention is that the ammonia water or urea water is atomized and fully mixed with the tail gas, at the same time, the required oxygen is provided for the denitrification reaction, and the denitrification efficiency is improved.

Description of drawings

Figure 1 is a schematic diagram of the composition of the marine diesel engine tail gas selective catalytic reduction denitrification system;

Figure 2 is a schematic diagram of the structure of the atomizer;

Figure 3 is a schematic diagram of the structure of the helical blade mixer

Figure 4 is a schematic diagram of a top view of a helical blade mixer

In the figure, 1-atomizer; 2-spiral blade mixer; 3-selective catalytic reduction denitration catalyst; 4-atomizing nozzle; 5-inner tube; 6-outer tube; 7-nozzle cap; 8- Sealing gasket; 9-compressed air chamber; 10-mixing hole; 11-liquid hole; 12-liquid pipe; 13 compressed air pipe.

Detailed ways

The present invention will be further described below in conjunction with drawings and embodiments.

An embodiment is a specific embodiment in which the atomizing nozzle has six mixing holes and six liquid holes. The selective catalytic reduction denitrification catalyst 3 is placed in the exhaust gas discharge pipe, and an atomizer 1 and a spiral blade mixer 2 are also arranged in the exhaust gas discharge pipe between the selective catalytic reduction denitrification catalytic converter 3 and the exhaust gas inlet. The atomizer 1 includes Atomizing nozzle 4, atomizing body and nozzle cap 7, the atomizing body is a double-layer pipe sleeve composed of inner tube 5 and outer tube 6, atomizing nozzle 4 is a cone nozzle, and the inside of the cone is connected to the bottom surface of the cone The compressed air chamber 9 is provided with six mixing holes 10 on the front side wall of the cone. The inner ends of the mixing holes 10 communicate with the compressed air chamber 9 and the outer ends are open. The included angle between the mixing holes 10 is 120°, the diameter of the mixing holes 10 is 1-5 mm, six liquid holes 11 are arranged in the side wall of the cone, the rear ends of the liquid holes 11 communicate with the bottom surface of the cone, and the front ends communicate with the mixing holes. 10 connected, the liquid holes 11 are distributed symmetrically along the cone, the angle between the two symmetrical liquid holes 11 is 30°, the diameter of the liquid holes 11 is 0.6-2mm, the bottom surface of the atomizing nozzle 4 and the front of the atomizing body are provided with nozzle caps 7 is connected by thread sealing, wherein the cone compressed air chamber 9 communicates with the front end of the inner tube 5 of the atomizing body, the liquid hole 11 in the side wall of the cone communicates with the front end of the outer tube 6 of the atomizing body, and the inner tube 5 of the atomizing body communicates with the front end of the atomizing body outer tube 6 The outer tubes 6 are sealed, the rear end of the inner tube 5 of the atomizing body is connected to the compressed air source through the compressed air tube 13, and the rear end of the outer tube 6 of the atomizing body is connected to the reducing agent source through the liquid tube 12, and the reducing agent is ammonia water or urea water; the helical blade mixer 2 is placed between the selective catalytic reduction denitrification catalyst 3 and the atomizer 1, and the helical blade mixer 2 is composed of a helical blade fixed on the inner wall of the cylinder, and the helical blade does not reach the circle The central part of the cylinder forms a through hole in the central part of the cylinder, and the helix angle of the helical blade is between 45 degrees and 60 degrees.

Diesel engine exhaust gas enters the exhaust pipe and is first mixed with ammonia water or urea water when passing through the atomizer 1, then passes through the spiral blade mixer 2, and achieves the purpose of sufficient mixing by changing the gas flow direction, and then passes through the selective catalytic reduction denitrification catalyst 3 for denitrification reaction.

The reducing agent ammonia water or urea water enters the atomizer through the liquid pipe 12, and the compressed air enters the atomizer through the compressed air pipe 13, and finally reaches the atomizing nozzle 4. In the mixing hole 10, the compressed air from the compressed air chamber 9 and the compressed air from the The ammonia water or urea water in the liquid hole 11 is mixed and atomized. Because the angle of 120° is formed between the two symmetrical mixing holes 10, the sprayed ammonia or urea water can be mixed with the tail gas of each part, and the angle of 30° is formed between the two symmetrical liquid pipes 11, so that the ammonia or urea water can be mixed with each other. The urea water flows into the mixing hole 10 smoothly. The atomizing nozzle 4 is fixed to the inner tube 6 by a spiral, and the atomizing nozzle 4 and the outer tube 6 are fixed by a nozzle cap 7 and sealed by a sealing gasket 8 .

The helical blade is fixed on the inner wall of the exhaust pipe, and the center is a through hole, which facilitates the flow of gas and reduces the resistance of the blade to the exhaust gas.

Claims (5)

1. The selective catalytic reduction denitrification system for marine diesel engine exhaust, including a selective catalytic reduction denitrification catalyst (3) placed in the exhaust pipe of marine diesel engine, characterized in that: the selective catalytic reduction denitrification system for marine diesel engine exhaust is also included in the The exhaust pipe is built in the atomizer (1) and the spiral blade mixer (2) between the selective catalytic reduction denitrification catalyst (3) and the exhaust gas inlet, and the atomizer (1) includes the atomization nozzle (4 ), an atomizing body and a nozzle cap (7), the atomizing body is a double-layer sleeve composed of an inner tube (5) and an outer tube (6); the atomizing nozzle (4) is a cone nozzle, There is a compressed air chamber (9) connected to the bottom surface of the cone inside the cone, and a mixing hole (10) is provided on the front side wall of the cone. The inner end of the mixing hole (10) communicates with the compressed air chamber (9), and the outer end is open. , there is a liquid hole (11) in the side wall of the cone, the rear end of the liquid hole (11) communicates with the bottom surface of the cone, the front end communicates with the mixing hole (10), the bottom surface of the atomizing nozzle (4) and the front of the atomizing body pass through the nozzle The cap (7) is sealed and connected, wherein the conical compressed air chamber (9) communicates with the front end of the inner tube (5) of the atomizing body, and the liquid hole (11) in the side wall of the cone communicates with the front end of the outer tube (6) of the atomizing body , the inner tube (5) of the atomizing body and the outer tube (6) are sealed, the rear end of the inner tube (5) of the atomizing body is connected to the compressed air source, and the rear end of the outer tube (6) of the atomizing body is connected to the reduction The agent source is connected; the spiral blade mixer (2) is placed between the selective catalytic reduction denitrification catalyst (3) and the atomizer (1), and the spiral blade mixer (2) is fixed on the inner wall of the cylinder The helical blade is composed of the helical blade, and the helical blade does not reach the center of the cylinder, so that the center of the cylinder forms a through hole. 2. The marine diesel engine tail gas selective catalytic reduction denitrification system according to claim 1, characterized in that: the mixing holes (10) of the atomizing nozzle have an even number of 4 to 10, symmetrically distributed along the front of the cone, two The included angle between the symmetrical mixing holes (10) is 120°, the liquid holes (11) have an even number of 4 to 10, and are symmetrically distributed along the cone, and the included angle between the two symmetrical liquid holes (11) is 30° °. 3. The marine diesel engine tail gas selective catalytic reduction denitrification system according to claim 3, characterized in that: the diameter of the mixing hole (10) of the atomizing nozzle is 1-5mm, and the diameter of the liquid hole (11) is 0.6- 2mm. 4. The marine diesel engine tail gas selective catalytic reduction denitrification system according to claim 1, characterized in that: the helical angle of the helical blade of the helical blade mixer (2) is between 45 degrees and 60 degrees. 5. The marine diesel engine tail gas selective catalytic reduction denitrification system according to claim 1, characterized in that: the reducing agent is ammonia water or urea water.

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