What flow meter should be used to measure liquid ammonia flow?
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Our company previously used differential transmitters to measure liquid ammonia flow, which resulted in large errors. What type of flow meter should be chosen if I want to replace the current one?
To ensure accuracy, it’s better to choose a mass flow meter; the ones used in our ammonia synthesis plant are from KROHNE
Vortex flow meters or mass flow meters work fine; just install them in strict accordance with the installation requirements
For mass flow meters, if it is a gas-liquid mixture, specific verification is required
Why is the orifice plate inaccurate? Bring over the specification sheet and I’ll help you do the calculations. Replacing an orifice plate costs a few hundred yuan – is it really necessary to spend tens of thousands?
Our company previously used differential transmitters to measure liquid ammonia flow, which resulted in large errors. Pay attention to whether the temperature and pressure are constant, and determine if temperature and pressure compensation is necessary. The accuracy required for a flow meter also depends on the purpose: is it for measurement or for general control purposes?
When it comes to measurement for routine production control, those who immediately suggest using mass flow meters are basically amateurs. Since an orifice plate was used in the original design, it is certainly the right choice to use a measuring instrument with lower costs for measurement purposes within the production process. If there are some issues with the use and maintenance of orifice plates, these can be appropriately improved or alternative flow meters for industrial use can be adopted – so why recommend mass flow meters that are relatively expensive? Furthermore, due to the volatility of liquid ammonia, in pipelines temperature increases or insufficient back pressure can sometimes cause partial vaporization, resulting in a two-phase liquid state. This is also a major reason why differential pressure flow meters cannot provide accurate measurements. Proper insulation (or cooling) of the pipeline allows the use of vortex flow meters or capacitive electromagnetic flow meters.
Pay attention to the pipeline back pressure to avoid vaporization. Differential pressure type is available as an option, at a lower price.