To valve procurement Engineers - How to select valves for black water system in coal gasification?
Coal water slurry gasification is one of the world’s most advanced technology on the entrained-flow coal gasification, which is widely used in the coal chemical enterprise. The working condition of the coal water slurry is very hard, as the key process of the pipeline,the valve selection becomes a headache problem for most of the valve procurement engineers.
1. The coal water slurry reaches a very high flow rate in the valve orifice, at the same time the coal slurry has a certain degree of hardness, so the erosion damage to the valve is quite serious.
2. The coal slurry is easy to be deposited to block the valve cavity, so the valve flow channel is required to be clear without dead space, the coal slurry particle is quite fine, is very easy to penetrate into the valve disc gap and make the valve disc to be jammed.
3.The coal slurry has a certain adhesive force, is very easy to form scales on the sealing face of the valve disc and valve seat, when the valve is fully closed, the leakage level is affected, so the valve is required to automatically remove the scaling.
So there are three special requirements to the valve applying on the black water system ：Erosion resistance, Anti-scaling, self-cleaning. The black water almost has no corrosion, so valve body and valve cover are selected with WCB material, the valve disc and valve seat are selected with general austenitic stainless steel which is hot compressed with a layer of hard alloy on the surface to anti erosion, and the adhesion of the of the ash water scaling is smaller than the coking deposit layer, the torque of the actuators is not required to be large.
How to select the valve for this system ? QUANSHUN R&D team carefully researched the working condition as following :
Application position：Feed pump inlet and outlet of settling tank for methanol gasification plant;
Medium: black water (ammonia, H2S and a small amount of pulverized coal particles);
Temperature: 80 ℃
Viscosity: 0.6 Pa.s;
In the beginning the customer uses the metal sealing ball valves, two valves in preparing and one in operating condition. About every 3 months change one pump, every time change the pump, the valves need to be opened, the valve opening time is two to three months per time. Whether the valve is open or closed, because the valve ball and valve seat are always contact, the medium is very easy to deposited to the sealing face between the valve ball and valve seat, resulting in the valve blocked.
According to the above working condition, QUANSHUN R&D team analyzed the reason why the metal sealing ball valve is blocked, and developed the new Y-type wear-resistance valve. After on-site trial and inspection, the valve structure is proved to be reasonable, and the performance is reliable, it not only solved the valve blocking problem, but also has longer working life than metal sealing ball valve. The trouble of valve procurement engineer is solved.
QUANSHUN Flow Control Valves, manufactured with heart and intelligence, is focused on industrial valves for more than ten years, and provided the best solutions to the harsh working conditions of the black water system for the valve procurement engineer!