Feasibility of adding a bypass to the main steam valve in the boundary area?
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The issue concerns the main steam valve in the plant’s boundary zone. Generally, these main steam valves are quite large – often measuring over a dozen inches in diameter. Whenever steam is introduced into the plant after maintenance, water hammer effects inevitably occur to some extent； One of the challenges here is that it’s difficult to control the opening degree of such large valves; even a slight movement of the handwheel can result in an excessive opening degree, leading to water hammer. I was wondering if it would be possible to add a small-sized bypass line to the main valve for this area; steam could be directed through the bypass line first, and the main valve opened only after the pipes have been warmed up. Would this not enhance safety and operability? Please share your opinions as well as the problems you have encountered when introducing steam and the solutions you used.
Isn’t it just like this, ///? . That’s our workshop.
I think it’s fine; it’s killing two birds with one stone!
Just add a reverse drain here to guide the water downward
This is called a heating pipeline; we have versions with DN25 diameter, featuring two valves and an air vent in between.
A secondary line should be added; we added one in ours, but it wasn’t very useful.
Water hammer phenomenon -- when steam needs to be introduced, locate the lowest point promptly to drain any accumulated water； It seems that the steam introduction specifications have requirements regarding the rate of temperature increase. Typically, steam supplied to the turbines in industrial units is routed through warming lines; such a system is not available in this area at the moment. It is indeed a good idea to use such warming lines for supplying steam to large-scale installations.
This is the conventional approach; large valves are difficult to control, so a bypass line is added to facilitate their opening and control.
In the catalytic unit I used to work in, which operated with 4.0 MPa steam, there were DN40 heating pipelines that worked very well for introducing steam
The main steam inlet valve along with the bypass valve (DN25) serve to warm the pipes when steam is introduced, thereby preventing liquid slugging.
These issues should be taken into account during pipeline design; adding them temporarily is not a good idea – attention must be paid to design and construction!