What exactly is a flapper door?
To put it bluntly, the baffle door is a "gate" in the pipeline, which is used to block or regulate the airflow. Think about it, the flue gas system of power plants, the inlet and outlet of desulfurization towers, the air flow in these places is hot and dirty, how can it be done without a decent door? What we always sayFlue gas baffle door、Desulfurization flue gas baffle doorIt looks alike, but it makes a big difference when used. One pipe of high-temperature flue gas and one pipe of desulfurization flue gas containing acidic medium will be directly scrapped if the wrong choice is made.
Single-axis double-baffle vs double-seal single-axis round-baffle door-the name is twisted, but the difference is very practical
The names of these two products are really mouthful, and I remembered them mixed at the beginning. Simply put:Double-sealed single-axis circular baffle doorThere are two seals, which have better sealing performance, and are suitable for desulfurization, which requires tight fitting, to prevent flue gas leakage; WhileSingle-axis double-flapper doorThe structure is simple, the switching speed is fast, and it is suitable for the positions in the flue gas system that need to be quickly isolated, such as the outlet of the induced draft fan of the boiler. And guess what? Two days ago, another customer mistakenly selected the entrance of the desulfurization tower as a single-axis double baffle. As a result, the seal was not tight, and the slurry leaked all over the floor, so it was too late to cry. Remember: If the sealing requirements are high, choose a double seal.
Manual or electric? It depends on the conditions
This is not absolutely good or bad, it depends on the conditions on the scene. Small diameter, infrequently operated pipes, withManual plug-in insulation doorThat's right. It's cheap and hassle-free. But if you work with the DCS automation system, or the pipeline is high and out of reach, then you have to goElectric plug-in insulation doorRemote control, saving labor. However, there is a key point: the electric actuator must be anti-corrosion, especially in the desulfurization environment. As soon as the acid mist drifts, ordinary actuators rust to death in a few months.
How to cooperate with the expansion joint and compensator? That's a good question
Upstream and downstream of the baffle door are usually equipped with expansion joints or compensators to absorb the thermal displacement of the pipe. Think about it, once the flue gas temperature changes, the pipe will expand and contract and deform, without cushioning, and the baffle door housing will be deformed by the top. Common collocations areMetal rectangular expansion jointOrNon-metallic expansion joints (fabric fiber expansion joints)Depending on the shape and temperature of the pipe. Metallic for high temperature flue gas, non-metallic for low temperature corrosive medium. Oh, by the way, andrubber compensatorAndRubber PTFE compensatorIt can also be used in some low-pressure applications, but attention should be paid to the corrosiveness of the medium.
Two details that are easy to overlook in model selection: the direction of the guide tube and the material of the sealing surface
Let's start with the deflector. If the direction of the guide tube on the expansion joint is installed backwards, the air flow directly erodes the sealing surface of the baffle door, and the life of the baffle door is halved. The correct direction of the deflector should be to follow the flow direction of the medium, protecting the bellows and seals. Let's talk about the sealing surface material. Many pictures use ordinary rubber to save trouble, and when it meets the acidic medium in the desulfurization flue gas, it will rot in two or three months. At this time, you have to use stainless steel or fluororubber, which is corrosion-resistant and high temperature-resistant. Don't underestimate this, the cost of replacing the seals once is enough to buy several baffle doors.
Finally, let's talk about the actual-installation location and maintenance space
This is really a lesson learned. Don't stuff the baffle door in the corner, it's too late to cry when you change the seal in the future. Allow the operating distance of at least one flange surface, about 400-500mm, so that the screwdriver and wrench can reach in. In addition, don't forget to set up an inspection platform upstream and downstream of the baffle door, especially for large sizesDesulfurization flue gas baffle doorOne person can't lift it at all. Old masters all know: leave 10cm more space when installing, and spend less than half a day in maintenance.
Okay, so much for today about baffle door selection. If you still have specific working conditions and parameters, please feel free to ask me, we can talk in detail.