Waste gas economizer lower smoke box capable of preventing flushing water from entering SCR (Selective Catalytic Reduction) reactor

Abstract

The top of the lower smoke box is connected with the waste gas economizer, the bottom of the lower smoke box is connected with the SCR reactor, the lower smoke box is provided with a cylindrical lower box body, the bottom of the lower box body is provided with a smoke inlet pipe, the smoke inlet pipe is a round pipe, and the top of the lower smoke box is open and is a smoke outlet; a compressed air outlet is formed in the lower box body and above the smoke inlet pipe, the compressed air outlet is in a horn shape, a compressed air inlet and a discharge port are formed in the bottom of the lower box body, the compressed air inlet is connected with the compressed air outlet through a hose, and the compressed air inlet and the discharge port are symmetrically formed in the two sides of the smoke inlet pipe. The compressed air inlet is connected with miscellaneous compressed air on the ship, and the pressure is 6-8 bar. According to the device, it is guaranteed that the smoke inlet pipeline is not immersed by flushing water, meanwhile, the device is used for protecting the smoke inlet pipeline from the flushing water dripping from the upper portion from entering, then it is guaranteed that no large amount of flushing fresh water enters the SCR reactor of the generator below, and normal operation of a smoke exhaust system of the generator is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of marine vessel design and construction, and specifically relates to a waste gas economizer lower smoke box that prevents flushing water from entering the SCR reactor. Background Technology

[0002] To meet Tier III requirements, almost all ship generators now employ low-pressure SCR systems to reduce NOx emissions. Additionally, considering the economic efficiency of ship operations, generator exhaust economizers are often added to the generator exhaust pipes.

[0003] In low-pressure SCR systems, generator exhaust gases must pass through an SCR reactor for catalytic reduction. This reaction requires relatively high exhaust temperatures; therefore, the generator exhaust gases must first pass through the SCR reactor before entering the generator exhaust economizer. The core component of the SCR reactor is the catalyst installed inside. The effectiveness of the catalyst is crucial to whether the generator's NOx emissions meet standards. This catalyst cannot come into contact with water. When the catalyst comes into contact with a large amount of water, its performance is reduced, affecting the catalytic reduction reaction. Simultaneously, the catalyst's structure is altered, resulting in decreased catalyst strength, ultimately leading to reactor failure and hindering repair and maintenance. In severe cases, it can increase the back pressure of the SCR reactor exhaust gases or even cause blockage.

[0004] Because the SCR reactor is located below the generator exhaust economizer, which accumulates a large amount of soot, it requires regular flushing with fresh water by the crew. During flushing, a significant amount of fresh water is released into the reactor. Furthermore, the generator exhaust economizer outlet is typically connected to the exhaust outlet. When the generator in this exhaust system is not running, the exhaust pipe is at room temperature. In rainy weather, rainwater will enter the exhaust system through the exhaust pipe, passing through the generator exhaust economizer and then into the SCR reactor. Repeated flushing will lead to catalyst deactivation, failing to achieve the goal of reducing NOx emissions. Summary of the Invention

[0005] To solve the above problems, the present invention provides a method for preventing flushing water from entering the exhaust gas economizer lower smoke box of the SCR reactor. The technical solution adopted is as follows:

[0006] A lower smoke box for an exhaust gas economizer that prevents flushing water from entering the SCR reactor. The top of the lower smoke box is connected to the exhaust gas economizer, and the bottom is connected to the SCR reactor. The lower smoke box has a cylindrical lower box body with a smoke inlet pipe at the bottom of the lower box body. The smoke inlet pipe is a circular pipe, and the top of the lower smoke box is open, serving as a smoke outlet.

[0007] A compressed air outlet is located inside the lower chamber and above the smoke inlet pipe. The compressed air outlet is funnel-shaped. A compressed air inlet and a vent are located at the bottom of the lower chamber. The compressed air inlet and the compressed air outlet are connected by a hose. The compressed air inlet and the vent are symmetrically located on both sides of the smoke inlet pipe. The compressed air inlet is connected to the ship's general-purpose compressed air supply, with a pressure of 6~8 bar.

[0008] Furthermore, in the aforementioned method of preventing flushing water from entering the lower flue gas chamber of the SCR reactor, the height of the flue gas inlet pipe within the lower chamber is 150 mm.

[0009] Furthermore, the exhaust gas economizer lower smoke box that prevents flushing water from entering the SCR reactor is further equipped with a reinforcing elbow plate inside the lower box.

[0010] Furthermore, in the aforementioned method of preventing flushing water from entering the lower smoke box of the SCR reactor, a manhole cover is provided on the wall of the lower box.

[0011] This invention addresses the problem of excessive flushing water flowing into the generator SCR reactor during the flushing process of the generator exhaust economizer, causing catalyst deactivation. By optimizing the internal structure of the lower smoke box of the generator exhaust economizer and increasing the height of the inlet pipe, flushing water is prevented from submerging the inlet pipe. Simultaneously, an additional compressed air line is added to prevent flushing water dripping from above into the inlet pipe when flushing is initiated. This ensures that a large amount of flushing water does not enter the generator SCR reactor below through the lower smoke box during the generator exhaust economizer flushing process. Furthermore, it prevents the generation of exhaust back pressure, ensuring the normal operation of the generator exhaust system. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the generator exhaust system;

[0013] Figure 2 This is a schematic diagram of the side section structure of the lower smoke box;

[0014] Among them, 1-SCR reactor, 2-exhaust gas economizer, 6-manhole cover, 9-lower smoke box, 10-smoke outlet, 11-smoke inlet pipe, 12-reinforcing elbow plate, 13-compressed air inlet, 14-compressed air outlet, 15-vent. Detailed Implementation

[0015] The invention will be further described with reference to the accompanying drawings.

[0016] A method to prevent flushing water from entering the exhaust gas economizer lower smoke box of the SCR reactor, such as... Figure 1 , 2As shown, the exhaust gas from the generator needs to pass through the generator SCR reactor and the generator exhaust gas economizer. The lower part of the generator exhaust gas economizer is the lower smoke box, and the upper part is the upper smoke box. During the flushing process of the generator exhaust gas economizer, the flushing water needs to pass through the lower smoke box before entering the generator SCR reactor. Rainwater needs to pass through the upper smoke box and the generator exhaust gas economizer before entering the generator SCR reactor. Therefore, this invention solves the problem of flushing water and rainwater entering the generator SCR reactor by optimizing the lower smoke box and the upper smoke box of the generator exhaust gas economizer. The lower smoke box includes an inlet pipe. After the generator SCR reactor, the exhaust gas enters the inlet pipe and then enters the generator exhaust gas economizer through the outlet. During the flushing process of the generator exhaust gas economizer, the flushing water also falls into the inlet pipe through the outlet and then enters the generator SCR reactor. Therefore, a compressed air inlet is added to the bottom of the lower smoke box, connected to the ship's commonly used miscellaneous compressed air, generally 6-8 bar. The lower chamber has a circular inlet pipe at its bottom and an open top for smoke outlet. Inside the lower chamber, above the inlet pipe, is a flared compressed air outlet. The bottom of the lower chamber has a compressed air inlet and a vent, connected by a flexible hose. The inlet and vent are symmetrically positioned on either side of the inlet pipe. During normal operation, the compressed air system is closed. During generator exhaust economizer flushing, the compressed air is activated. Due to the special structure of the compressed air outlet, an umbrella-shaped airflow pattern is created, causing flushing water dripping from above to be blown away by the compressed air and prevented from entering the inlet pipe. A vent is added at the bottom of the lower chamber to temporarily store the flushing water in the bilge tank. Meanwhile, the height of the inlet pipe entering the lower smoke box was increased to 150mm to ensure that even with excessive flushing water, it would not accumulate due to poor drainage, submerge the smoke outlet, or leak into the generator SCR reactor below. To prevent the accumulation of drainage water and increased weight from damaging the smoke box structure, a reinforcing elbow plate was added to the bottom, along with a manhole cover, allowing crew members to periodically open the smoke box to inspect and clean any residual soot at the bottom.

[0017] This patent provides a solution to the problem of generator exhaust gas economizer flushing water leaking into the generator SCR reactor. Simply adding a compressed air interface to the lower smoke box of the generator exhaust gas economizer and making certain structural optimizations can perfectly solve the water leakage problem without increasing the exhaust back pressure in the lower smoke box. This solution is applicable to all ships currently equipped with generator exhaust gas economizers that need to meet Tier III standards. For ships already delivered or under construction, the problem can also be solved by modifying the lower smoke box.

Claims

1. A waste gas economizer lower smoke box that prevents flushing water from entering the SCR reactor, characterized in that, The top of the lower smoke box is connected to the exhaust gas economizer, and the bottom is connected to the SCR reactor. The lower smoke box has a cylindrical lower box body with a smoke inlet pipe at the bottom of the lower box body. The smoke inlet pipe is a circular pipe, and the top of the lower smoke box is open, serving as the smoke outlet. A compressed air outlet is located inside the lower chamber and above the smoke inlet pipe. The compressed air outlet is funnel-shaped. A compressed air inlet and a vent are located at the bottom of the lower chamber. The compressed air inlet and the compressed air outlet are connected by a hose. The compressed air inlet and the vent are symmetrically located on both sides of the smoke inlet pipe. The compressed air inlet is connected to the ship's general-purpose compressed air supply, with a pressure of 6~8 bar.

2. The exhaust gas economizer lower smoke box for preventing flushing water from entering the SCR reactor according to claim 1, characterized in that, The height of the flue pipe inside the lower chamber is 150mm.

3. The exhaust gas economizer lower smoke box for preventing flushing water from entering the SCR reactor according to claim 1, characterized in that, A manhole cover is provided on the wall of the lower box.

4. The exhaust gas economizer lower smoke box for preventing flushing water from entering the SCR reactor according to claim 1, characterized in that, A reinforcing elbow plate is installed inside the lower housing.

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