Discussion on the installation of safety valves and rupture discs in atmospheric pressure reactors
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Our company has a new chemical plant in Jiangxi, and we commissioned a design firm based in Nanchang, Jiangxi (a branch of Jiangsu Zhongjian) to carry out the chemical engineering design for us. On the PID diagrams, designs for rupture discs, safety valves, and flame arrestors were included for all reactors and tanks. However, only two of our reactors generate gas; the rest are at atmospheric pressure, and some of them even operate in a aqueous medium. Yet these devices were installed without any consideration for such differences. I asked them why they included them, and they replied that it was a precautionary measure – that they were necessary. I think they are overreacting; designing in such an indiscriminate manner, without taking into account the actual operational conditions, is irresponsible. Moreover, atmospheric pressure reactors are connected to heat exchangers, and their exhaust gases are routed into the main exhaust system of the workshop. I’m not sure what your thoughts are on such a design.
From a process perspective, if gas is released during the reaction, it is necessary to install a safety valve even when operating at atmospheric pressure. The design institute should have conducted a HAZOP analysis; it is necessary.
Only 2 of the reactors generate nitrogen dioxide emissions; the rest carry out normal reactions such as acidolysis and neutralization, low-temperature crystallization, and activated carbon decolorization. There is little reflux. Safety valves and burst discs have been installed in all the intermediate storage tanks; it’s not clear whether this is due to new requirements in Jiangxi province
Check for any sources of pressure, including reaction heat; it cannot be simply assumed that safety valves are not needed just because the operation is at atmospheric pressure.
It depends on whether the reaction process falls under hazardous chemical processes of type 1, as well as on characteristics such as exothermic reactions and the risk of temperature spikes. If it involves hazardous chemical processes, safety accessories as well as automatic control and safety interlock measures must be installed in accordance with the relevant requirements; otherwise, it will be difficult to pass the safety assessment and safety review.