Waste gas economizer smoke box capable of preventing water from entering SCR (Selective Catalytic Reduction) reactor
By optimizing the structure of the exhaust gas economizer's smoke box, water was prevented from entering the SCR reactor, thus solving the problem of catalyst failure and enabling the SCR reactor to operate normally and meet NOx emission standards.
Patent Information
- Application Number
- CN202423133667.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2026-01-23
- Estimated Expiration
- 2034-12-19
AI Technical Summary
The catalyst in an SCR reactor degrades in performance when it comes into contact with water, leading to the failure of the catalytic reduction reaction, affecting NOx emissions, and potentially causing reactor blockage or increased back pressure. Existing technologies are unable to effectively prevent water from entering.
An exhaust gas economizer smoke box was designed to prevent water from entering the SCR reactor. By optimizing the structure of the upper and lower smoke boxes, adding compressed air pipelines and rainwater collection trays, flushing water and rainwater are prevented from entering the SCR reactor. The rainwater collection tray is made of 316L stainless steel and reinforced elbow plates are used to ensure structural stability.
This effectively prevents the catalyst from coming into contact with water, maintains the catalyst's performance, avoids reactor failure and back pressure increase, and ensures the normal operation of the generator exhaust system.
Smart Images
Figure CN223818471U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of marine vessel design and construction, and specifically relates to an exhaust gas economizer smoke box that prevents 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 address the aforementioned problems, this invention provides an economizer flue gas chamber that avoids water ingress into the SCR reactor. The technical solution adopted is as follows:
[0006] An exhaust gas economizer smoke box for preventing water from entering an SCR reactor includes an upper smoke box and a lower smoke box. The exhaust gas economizer is located between the upper smoke box and the lower smoke box. The upper smoke box has a cylindrical upper box body, and the top of the upper box body has a smoke outlet pipe. The smoke outlet pipe is a circular pipe. The bottom of the upper smoke box is open and serves as a smoke inlet.
[0007] Inside the upper housing, below the smoke outlet pipe, there is a rain-collecting tray. The rain-collecting tray is funnel-shaped with a drain outlet in the center. There is a gap between the drain outlet and the smoke inlet. The drain outlet is connected to a vent pipe, the end of which protrudes from the housing wall. The diameter of the funnel-shaped opening of the rain-collecting tray is larger than the diameter of the smoke outlet pipe.
[0008] The lower smoke box has a cylindrical lower body with a smoke inlet pipe at the bottom. The smoke inlet pipe is a circular pipe, and the top of the lower smoke box is open as a smoke outlet.
[0009] 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 flexible hose. The compressed air inlet and the vent are symmetrically located on both sides of the smoke inlet pipe.
[0010] Furthermore, the exhaust gas economizer smoke box that avoids water entering the SCR reactor is further provided with a manhole cover on the upper box wall, and the manhole cover is symmetrically arranged with the end of the vent pipe.
[0011] Furthermore, the exhaust gas economizer smoke box described above, which avoids water ingress into the SCR reactor, has a compressed air inlet connected to the ship's general-purpose compressed air supply at a pressure of 6-8 bar.
[0012] Furthermore, in the aforementioned waste gas economizer smoke box that avoids water ingress into the SCR reactor, the height of the smoke inlet pipe within the lower box is 150mm.
[0013] Furthermore, the exhaust gas economizer smoke box that avoids water ingress into the SCR reactor is further equipped with a reinforcing elbow plate in the lower chamber.
[0014] Furthermore, the exhaust gas economizer smoke box that avoids water ingress into the SCR reactor is further provided with a manhole cover on the lower box wall.
[0015] The aforementioned waste gas economizer smoke box, which avoids water ingress into the SCR reactor, further features a rain-receiving tray with a funnel-shaped opening that forms a 15° angle with the horizontal plane.
[0016] Furthermore, the exhaust gas economizer smoke box that avoids water ingress into the SCR reactor is further improved by using a rain collection tray made of 316L stainless steel with a plate thickness of 5mm.
[0017] This invention addresses the problem of excessive flushing water flowing into the generator SCR reactor during the flushing process of the generator exhaust economizer, as well as rainwater entering the SCR reactor through the exhaust pipe outlet during rainy weather, causing catalyst deactivation. By optimizing the internal structure of the upper and lower smoke boxes of the generator exhaust economizer, the height of the lower smoke box inlet pipe is increased to ensure that flushing water does not submerge the inlet pipe. Simultaneously, an additional compressed air line is added, which is opened during flushing to prevent flushing water dripping from above from entering the inlet pipe. 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. It also prevents the generation of exhaust back pressure, ensuring the normal operation of the generator exhaust system. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the overall structure of the generator exhaust system;
[0019] Figure 2 This is a schematic diagram of the side section of the upper smoke box;
[0020] Figure 3 This is a schematic diagram of the side section structure of the lower smoke box;
[0021] Among them, 1-SCR reactor, 2-exhaust gas economizer, 3-upper smoke box, 4-smoke inlet, 5-smoke outlet pipe, 6-manhole cover, 7-vent pipe, 8-rain collection tray, 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
[0022] The invention will be further described with reference to the accompanying drawings.
[0023] An economizer flue gas chamber that avoids water inlet to the SCR reactor, such as Figure 1As shown, the flue gas discharged 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's flue gas passes through the generator SCR reactor, it 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. Figure 3 As shown, the lower chamber has a flue gas inlet pipe at the bottom, which is circular. The top of the lower chamber is open, serving as the flue gas outlet. Inside the lower chamber, above the flue gas inlet pipe, is a compressed air outlet, which is funnel-shaped. The bottom of the lower chamber has a compressed air inlet and a vent, connected by a flexible hose. The compressed air inlet and vent are symmetrically located on both sides of the flue gas inlet pipe. During normal operation, the compressed air 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 air structure is formed, spreading outwards. When flushing water drips from above, the compressed air's blowing action deflects the water dripping directly above the flue gas inlet pipe, preventing it 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.
[0024] like Figure 2 As shown, the upper smoke box has a cylindrical upper body with a smoke outlet pipe at the top. The smoke outlet pipe is circular, and the bottom of the upper smoke box is open, serving as the smoke inlet. Inside the upper body, below the smoke outlet pipe, is a rain-collecting tray. The rain-collecting tray is funnel-shaped with a drain outlet in the center. There is a gap between the drain outlet and the smoke inlet. The drain outlet is connected to a vent pipe, the end of which protrudes from the wall of the box. The diameter of the funnel-shaped opening of the rain-collecting tray is larger than the diameter of the smoke outlet pipe.
[0025] The generator's flue gas passes through the generator SCR reactor and the generator exhaust gas economizer before entering the flue gas inlet and then exiting into the atmosphere through the exhaust pipe. During rainy weather, rainwater also falls into the flue gas inlet through the exhaust pipe, passes through the generator exhaust gas economizer, and then enters the generator SCR reactor. Especially when the generator is not running, the temperature inside the exhaust system is low, and the rainwater will not evaporate, which can lead to catalyst deactivation in the reactor.
[0026] Therefore, a drain pipe is added to the side of the upper smoke box, and a rain catcher is installed directly above the smoke inlet. A detailed drawing of the rain catcher is shown in the attached diagram. The inner diameter of the rain catcher needs to be slightly larger than the inner diameter of the smoke outlet pipe to ensure that rainwater dripping from above is caught by the rain catcher. Since the rain catcher will be in contact with rainwater for a long time, it needs to be corrosion-resistant; the material needs to be 316L stainless steel with a thickness of 5mm. Figure 3 As shown, the rain-collecting tray should maintain a 15° slope. Similarly, a sufficiently large gap should be left between the rain-collecting tray and the lower smoke box shell to ensure unobstructed smoke exhaust. This ensures that the collected rainwater flows into the bottom of the rain-collecting tray, while also ensuring that the smoke entering from the smoke inlet flows smoothly into the smoke outlet pipe without being obstructed by the rain-collecting tray, thus preventing an increase in exhaust back pressure. Additionally, the opening at the bottom of the rain-collecting tray needs to be slightly smaller than the inner diameter of the lower vent pipe. The connection between the vent pipe and the rain-collecting tray is as follows: Figure 3 This method ensures that rainwater does not remain in the rain collection pan. Instead, it is drained through the drain pipe into the bilge tank for temporary storage. Additionally, manhole covers are added to allow crew members to periodically open the smoke box to inspect and clean any remaining soot inside.
[0027] This patent provides a solution to the problem of flushing water and rainwater discharge from generator exhaust economizers into the generator SCR reactor. By simply optimizing the structure within the exhaust economizer's smoke box, the problem of flushing water and rainwater discharge can be perfectly resolved without increasing the exhaust back pressure within the smoke box. This solution is applicable to all ships currently equipped with generator exhaust economizers that meet Tier III standards. For ships already delivered or under construction, the problem can also be solved by modifying the smoke box.
Claims
1. A waste gas economizer smoke box for preventing water ingress into an SCR reactor, characterized in that, It includes an upper smoke box and a lower smoke box. The exhaust gas economizer is located between the upper smoke box and the lower smoke box. The upper smoke box has a cylindrical upper box body. The top of the upper box body has a smoke outlet pipe. The smoke outlet pipe is a circular pipe. The bottom of the upper smoke box is open and serves as the smoke inlet. Inside the upper housing, below the smoke outlet pipe, there is a rain collection tray. The rain collection tray is funnel-shaped with a drain outlet in the center. There is a gap between the drain outlet and the smoke inlet. The drain outlet is connected to a drain pipe. The end of the drain pipe extends out from the housing wall. The diameter of the funnel-shaped opening of the rain collection tray is larger than the diameter of the smoke outlet pipe. The lower smoke box has a cylindrical lower box body with a smoke inlet pipe at the bottom. The smoke inlet pipe is a circular pipe, and the top of the lower smoke box is open as a 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 flexible hose. The compressed air inlet and the vent are symmetrically located on both sides of the smoke inlet pipe.
2. The exhaust gas economizer smoke box for avoiding water ingress into the SCR reactor according to claim 1, characterized in that, Manhole covers are installed on the walls of the upper housing, and the manhole covers are symmetrically positioned with the ends of the discharge pipes.
3. The exhaust gas economizer smoke box for avoiding water ingress into the SCR reactor according to claim 1, characterized in that, The compressed air inlet is connected to the ship's general compressed air supply, with a pressure of 6~8 bar.
4. The exhaust gas economizer smoke box for avoiding water ingress into the SCR reactor according to claim 1, characterized in that, The height of the flue pipe inside the lower chamber is 150mm.
5. The exhaust gas economizer smoke box for avoiding water ingress into the SCR reactor according to claim 1, characterized in that, A reinforcing elbow plate is installed inside the lower housing.
6. The exhaust gas economizer smoke box for avoiding water ingress into the SCR reactor according to claim 1, characterized in that, A manhole cover is provided on the wall of the lower box.
7. The exhaust gas economizer smoke box for avoiding water ingress into the SCR reactor according to claim 1, characterized in that, The funnel-shaped opening of the rain-receiving tray forms a 15° angle with the horizontal plane.
8. The exhaust gas economizer smoke box for avoiding water inflow into the SCR reactor according to claim 1, characterized in that, The rain catcher is made of 316L stainless steel with a thickness of 5mm.