Why isn’t a safety valve installed on the urea synthesis tower?
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Why isn’t a safety valve installed on the synthesis tower for urea aqueous solutions? And is it the high-voltage equipment that isn’t installed? Is there any logic to it? This post was last edited by 1025199692 on 2009-4-28 21:16]
The reason why a safety valve is not installed in the synthesis tower might be that there is already a pressure reducing valve at the outlet, allowing pressure to be controlled via the regulating valve; moreover, safety valves are installed on the pipelines for the three reactants； If the overpressure is only slight, the regulating valve will be opened to release the pressure; if it’s severe, an emergency shutdown is necessary – the three materials must be cut off and P4 must be increased. Even safety valves are of no use in such situations. This is just a beginner’s understanding; I hope experts can correct me.
The pressure in the synthesis tower is very high, and overpressure can easily occur during material feeding. It is necessary to install a valve for this purpose; otherwise, it will be difficult to control overpressure once it occurs. I’m not sure what process you use – have you installed a vent valve at the gas outlet of your synthesis tower?
It is not installed on the synthesis tower equipment, but a safety valve is installed on the gas pipeline at the top of the tower. Steam insulation is required to prevent crystallization from occurring due to low temperatures, which could otherwise cause blockages in the pipelines after the safety valve activates.
A safety valve is installed on the exhaust pipe of the synthesis tower; high-pressure equipment is equipped with safety valves for safety reasons, to ensure safe operation
Urea synthesis towers in aqueous solution full-circulation processes generally do not have safety valves; instead, safety valves are installed at the outlets of the carbon dioxide compressor, liquid ammonia pump, and methamine pump, so that pressure can be released from there in case of overpressure. The compressor is also equipped with an overpressure trip interlock device, all of which serve to ensure the safe operation of the synthesis tower. Safety valves are generally installed at the gas-phase outlet of carbon dioxide stripping urea synthesis towers; the requirements vary depending on the process.
Most of our pressure systems are equipped with two safety valves each
The urea synthesis tower in the closed-loop aqueous solution process that I have worked with is not equipped with a safety valve, as safety valves are installed at the outlets of the carbon dioxide compressor, liquid ammonia pump, and methylamine pump. If the synthesis tower experiences overpressure, the main pipelines at the outlets of these compressors and pumps will also experience overpressure, prompting the safety valves to activate and reduce the pressure in the synthesis tower. Currently, compressors and ammonia pumps are equipped with overpressure trip interlock devices to ensure the safe operation of the synthesis tower.
The urea synthesis tower has leak detection holes; these are the most important accessories of the urea synthesis tower! The urea synthesis tower is a type of enclosed container
Safety valves are installed at the outlets of the carbon dioxide compressors, liquid ammonia pumps, and methylamine pumps to release pressure in case of overpressure. The compressor is also equipped with an overpressure trip interlock device, all of which serve to ensure the safe operation of the synthesis tower. Safety valves are generally installed at the gas-phase outlet of carbon dioxide stripping urea synthesis towers; the requirements vary depending on the process.
The reason why a safety valve is not installed in the synthesis tower might be that there is already a pressure reducing valve at the outlet, allowing pressure to be controlled via the regulating valve; moreover, safety valves are installed on the pipelines for the three reactants； If the overpressure is only slight, the regulating valve will be opened to release it. Last edited by lxq700918 on 2009-4-10 22:58.]
There is no need to install safety valves on the urea synthesis tower, as safety valves are already present on the feed pipelines of the tower; for example, safety valves are installed on the high-pressure carbon dioxide pipeline as well as on the pipelines exiting the compressor. In the event of overpressure, these valves will activate before the fluid reaches the tower
The feed pipes are equipped with safety valves, and the control valves on the discharge pipes can also reduce pressure; therefore, there is no need to install additional safety valves.
In fact, the relevant regulations stipulate that pressure vessels should be equipped with safety accessories, but these do not necessarily have to be installed directly on the pressure vessel itself. Regulation 141: Operating pressure vessels shall be equipped with safety relief devices (safety valves or burst disc systems) in accordance with the design requirements. When the pressure source is external to the pressure vessel and is under reliable control, a safety relief device does not need to be installed directly on the pressure vessel.
The pipes of the synthesis tower are equipped with safety valves, though they are not located on the tower itself. Moreover, in the event of an accident, there are very thorough measures for isolation and venting. One should consider issues comprehensively.
Our plant’s methanol synthesis tower is not equipped with a safety valve. However, the drum that regulates the pressure in the methanol synthesis tower is equipped with 2 safety valves and a pressure relief valve.
Our plant uses the carbon dioxide stripping method; the gas-phase pipes in our urea synthesis tower are equipped with safety valves, which should provide the same level of protection as those installed on the equipment itself.
The main reaction in the urea synthesis tower is the dehydration of methylamine. Unlike a boiler, it is not possible to control temperature and pressure directly; therefore, by controlling the temperature and pressure of the feed material, the temperature and pressure in the synthesis tower can be regulated, preventing overpressure. This post was last edited by lxq700918 on 2009-4-10 23:15.]
Original poster, let me tell you why the synthesis tower used for ammonia stripping doesn’t have a safety valve! The outlet valve of the synthesis tower (commonly referred to as HV-09203) is a butterfly valve, with the valve disc having a 30% notch. In other words, even when everything is turned off, there is still a 30% opening, so it remains connected to other devices in the high-pressure system, allowing use of their safety valves.