[Original Discussion] Based on years of experience in wear resistance, I have summarized the issues related to the wear-prone nature of the flash buffer devices in the angle valves of gasification furnaces...
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Currently, the high flash point valves used in vaporization furnaces are generally made of ordinary cast bimetallic materials. These materials expand and contract with temperature changes, and they are not metallurgically bonded to the outer steel structure; as a result, they cannot be welded or repaired. This makes it difficult to avoid the formation of pores and inclusions. Moreover, cavitation and shock waves within the flash vaporization buffer device can easily cause the wear-resistant layer to peel off, requiring the entire valve to be replaced in such cases. The surfacing with a high-chromium alloy bimetallic layer precisely compensates for the shortcomings of casting: it offers excellent wear resistance, is metallurgically bonded to the outer steel structure, has a high bonding strength between the wear-resistant layer and the outer steel, can withstand temperature changes and impacts, does not suffer from cracking or detachment, and can also be repaired locally – the wear-resistant layer can be thickened in areas that are severely worn, thereby **increasing the service life of the flash vaporization buffer device.** The bottom and straight pipe sections can be designed with various options based on the specific conditions at the site. Currently, flash vapor buffering devices fabricated by surfacing welding are being used in many projects, with a service life of over 2 years, and they are gradually gaining recognition in the market. It has achieved excellent results in Shenhua Ningmei Olefins Company, Shenhua Coal-to-Oil Project, and Inner Mongolia HuiNeng Coal-to-Natural Gas Project.
Buffer device behind the corner valve; currently, many such devices are in the form of a tee, with the corner valve located at the top. Most damage to the buffer device is caused by wear and tear; cases where it comes loose due to the casting not being integrated with the housing are extremely rare. Ultimately, it comes down to seeing which one has more durable castings or wear-resistant layers; as for the wear resistance that can be achieved through surfacing, in practical applications, the process of surfacing the worn areas presents significant difficulties due to the design of the buffers.
I have been working in casting for five or six years now. Let me start by talking about the casting process: first, the dimensions are determined, then foam is applied to the material, it’s placed in a sand box, the appropriate mixture is prepared, molten iron is poured in, and once casting is complete, what should be done to deal with pores, inclusions, cracks, and gaps? If the gap is large, it should be repaired with welding; for smaller gaps, iron putty is used for aesthetic reasons. Since there is gas corrosion within the material, and casting processes create gaps, gas can get into these gaps and cracks. Over time, the entire piece may come apart. The surfacing layer has no slag inclusions, achieving full metallurgical bonding; gas corrosion does not occur. One of the reasons why the buffer device wears out easily is cavitation. I’m not aware of the operating conditions in your company, but I’ve seen that in many buffer devices, the components fall off one by one. As for what you mentioned about the difficulty in performing surfacing welding, what will happen if parts of your company’s products come loose? Will those products have to be discarded entirely? For surfaced parts, spare parts can be replaced; the removed section can be repaired and reused as well. This buffering device also depends on the specific conditions; in some companies where the load is excessive, wear and tear are naturally severe. This is purely my personal opinion; I welcome any discussions. By the way, I am also working in casting at the moment.
Wear-resistant pipes used in coal washing plants are generally ceramic-lined wear-resistant pipes; the outer rigid layer of these pipes is made of 20# seamless steel tubes. The available sizes include 159, 219, 325, 426, etc., with a wall thickness of 1.0 in terms of pressure rating. The ceramic tiles used for the wear-resistant pipe lining are made of 92% high-purity corundum ceramics, with a hardness of over 85 and a density of ≥3.6 g/cm3. The wear-resistant pipe with ceramic lining is connected using flanges, facilitating installation and construction. Wear-resistant pipes with ceramic lining are used not only in the power industry but also across sectors such as metallurgy, coal, petroleum, chemicals, building materials, and machinery.