I would like to ask about screw feeders and rotary feeders used for coal powder transportation in front of the gasification furnace
Thread Content
I took a look at the coal powder handling system in front of the Shell gasifier, and I have two questions for the experts here. The fine coal powder generated by the coal grinder enters the coal powder storage bin after passing through a bag filter. Between the bag filter and the coal powder storage bin, a rotary feeder, a nitrogen purge valve, a vibrating screen, and a screw feeder are arranged in sequence. So, the question arises: 1. Why is it necessary to set up both a rotary feeder and a screw feeder at the same time? What are their respective functions? 2. Are the large particles separated by the vibrating screen blown away using nitrogen? Since this is clearly a fully solid-phase system (with very little gas phase), how can such purging be achieved? Question 1 supplement: If the two conveying devices are installed for the vibrating screen, then why are a rotary feeder and a screw feeder also used in the process of feeding limestone from the storage bin to the coal grinder? I’m completely puzzled; I hope experts and seasoned professionals can offer some guidance~~~
Reply to 2# moonshrine: My personal opinion is that the rotating feeder is used to ensure that a certain amount of coal powder enters the screw feeder. Without a rotating feeder, the coal powder would fall into the screw feeder due to gravity, which could lead to jams.
We don’t use vibrating screens; instead, we use electric fiber separators, which require manual cleaning at regular intervals.
1. When shell powder gasification first arrived in China, no vibrating screen was installed. During actual operation, it was found that the coal fed into the coal grinder contained fibers, as well as lightweight materials such as fast-food containers, which entered the coal powder system along with the coal powder via the carrier gas. Without proper screening, these materials could cause sticking and blockages in the pipeline components and valves along the route to the furnace, leading to fluctuations in the coal supply volume; in severe cases, this could result in shutdowns. Therefore, a vibrating fiber sieve was added later; its purpose was not to sieve out large particles of coal dust (the particle size of this coal dust is controlled after passing through the coal grinder’s rotary separator), but rather to separate and trap fibers and flaky lightweight materials ； 2. The rotary feeder, as the name implies, ensures continuous and steady feeding; it is a volumetric feeder that functions like a ladle rotating continuously to scoop up material and convey it downward. A variable-frequency motor is used to control the flow rate, and gas is employed at its upper part to achieve fluidization – without this, the feeding process may not be uniform ； 3. Screw conveyors are used because the height from the coal storage area beneath the bag filter to the rotating feeder is almost the same as the height of the top of the coal silo behind it. Since these devices are located in different frames and operate at atmospheric pressure, pneumatic conveying is not possible; therefore, screw feeders must be used to transport the coal. There was also consideration of using a structure similar to that of rural water wheels, but chain-based systems for long distances are prone to damage, so screw conveyors remain the safer and more reliable option. However, there is a new idea: the bag filter can be raised and placed above the coal powder silo, or this large spiral conveyor could be omitted. 4. What else? I can’t see what you’re about to ask next, and I can’t remember it either; you’ll need to think about it on your own. The answers are for reference only and cannot be verified. O(∩_∩)O~
What are the domestic brands of rotary feeders, and what are their prices?
This kind of product comes with a price that reflects its quality; it depends on operating conditions and technical requirements. What seems like a simple rotating feeder can cost tens of thousands, or even hundreds of thousands of dollars, so it’s impossible to compare prices
It’s clear that the poster has encountered this many times in real life; could they post a thread with pictures and explanations? Looking forward to it very much