【Major Industrial Equipment in the Chemical Industry】092-20-inch Coal Chemical Lock Hopper System Double Disc Valve

The double-disc valve is a special type of valve designed specifically for the cut-off valves in coal chemical hopper systems. Throughout the years, valve failures have been a significant factor limiting the stable operation of gasification units; even the online service life of imported valves rarely exceeds 4,000 hours. To overcome this technical bottleneck, Antway innovatively introduced disc valves into this field, eventually developing the world’s first dual-disc valve. This design increased the valve’s lifespan by 4-5 times, thereby saving a great deal of resources and significantly enhancing the economic benefits for customers. Currently, Antway double-disc valves have been used in projects such as Shenhua Ningmei’s 4 million tons per year coal-to-oil production facility, Lu’an Group’s 4 million tons per year coal-to-oil plant, Datong Coal Industry Group’s coal-to-methanol production facility, the renovation and expansion of Mingshui Chemical Plant, and the second phase of Xinneng Energy’s operations. Their longevity and reliability have won high praise from customers!

It is indeed the largest so far.

What is the performance in the industry?

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Features and solutions of double-disc valves: 1. Rapid wear of the sealing surfaces. In ordinary valves, the sealing surfaces are in contact with the medium at the same point. Double-disc valve: Rotating valve disc, with the valve disc and seat capable of self-grinding against each other. Within the service life, the more the valve disc and seat are ground, the better the fit and the better the sealing performance. 2. The leakage rate of these valves exceeds the required levels very quickly after use; ordinary valves, on the other hand, maintain a tight seal only right after being used. Double-disc valve: face seal, self-rotating disc, self-grinding, and hard seal with an HRA of up to 86.5. The valve maintains long-term sealing after use. 3. Debris accumulated in the material enters between the sealing surfaces. In ordinary valves, the valve seat lacks the ability to clean itself or the pre-pressure is insufficient. In double-disc valves, there is high pre-pressure, along with valve discs having sharp edges and a flat valve seat. The impact force of the piled material thus reduces erosion. 4. The flow of material causes erosion of the valve seat surface. In ordinary valves, protrusions on the valve core or changes in the flow path lead to a sudden change in the direction of the flow lines as the valve is opened and closed. Double-disc valve: The planar sealing surface is perpendicular to the flow direction, so the direction of the flow does not change abruptly during back-and-forth movement. It better counters pressure and temperature changes, ensuring that the packing is subjected to even pressure; at the same time, it mitigates the damage caused to the packing by lateral forces on the valve stem, reducing maintenance time and improving operational efficiency. 5 External leakage in ordinary valves: The valve stem damages or scratches the O-rings and packing. Double-disc valve: spring-loaded packing, a rotatably fixed shaft stem with no upward movement, and double bushings. It better counters pressure and temperature changes, ensuring that the packing is subjected to even pressure; at the same time, it mitigates the damage caused to the packing by lateral forces on the valve stem, reducing maintenance time and improving operational efficiency. 6. Thermal locking in ordinary valves: Different thermal expansion rates of materials lead to mismatches in tolerance fits. Double-disc valve: springs are installed between the valve discs and their driving mechanism, it features a smooth valve stem and a threadless design. Compensate for vibration and thermal stress. 7. Excessive pressure drop leads to a reduction in flow rate. Ordinary valves: flow channels with reduced diameter. Double-disc valve: full-channel flow. There is no throttling in the fluid flow, which makes it possible to use valves of smaller size.

In the pulverized coal gasification process, lockhopper equipment is used in the sections for pressurized feeding of pulverized coal and slag removal (ash removal) from the gasifier to carry out frequent operations such as coal feeding and slag discharge at regular intervals (every 30 minutes). The lockhopper valves, balance valves, and slag locking valves, as key valves, determine whether the gasifier can operate properly depending on their design quality. These valves operate in conditions of gas-solid mixture (coal powder + carbon dioxide) and solid-liquid mixture (slag water), at an operating pressure of around 4.9 MPaG, with a maximum allowable differential pressure of 6.2 MPaG; the inlet temperature is 100 degrees Celsius. In this operating condition, the medium often contains high-hardness particles, which cause severe erosion of the valve internals, particularly the sealing surfaces of the valve stem and seat. For instrument selection, two-way metal hard-sealed wear-resistant ball valves are commonly used. Although such valves are now produced domestically and thus offer a significant price advantage over imported ones, their high failure rate and short service life, due to issues with their structural design, result in unsatisfactory performance. The main reason for this is that in the structure of ball valves, coal dust tends to accumulate in the gaps around the metal seat used for sealing as well as around the valve itself, which causes the sealing surface to wear out easily and damages the hard metal coating on the valve core. During frequent opening and closing, since the sealing surface of the ball valve remains in the same position, the valve’s seal fails very quickly.