Medium-pressure nitrogen can be stored in tanks, and then a pressure regulator can be used to convert it into low-pressure nitrogen
Thread Content
Since the maximum amount of nitrogen that can be used is 4,000 cubic meters per hour, while the nitrogen production capacity is 2,400 cubic meters per hour, the owner wants to use a 2.5 MPa nitrogen compressor to pump nitrogen into the storage tank, and then use a pressure regulator to adjust the output pressure to 0.6 MPa; this way, more nitrogen can be stored in the tank. I was unable to find the critical compression ratio for nitrogen. Based on the values for air compressors, it’s probably around 1.50 or so. In other words, there’s no need to compress nitrogen to 2.0 MPa or 2.5 MPa using this method; 1.0 MPa is sufficient. Otherwise, even if higher pressures are applied, it won’t enable storing more nitrogen according to its critical compression ratio. I would appreciate everyone’s advice on this matter. Thank you
This post was last edited by CHANGBAISHI on 2019-5-27 18:42. This issue is similar to the use of oxygen/nitrogen in converter steelmaking. The problem is that your gas production volume is only 2400 Nm3/h; the actual production demand (average demand?) ) is a flow rate of 4000 Nm3/h. No matter how large the gas storage tank in that intermediate stage is, it won’t meet your needs; instead, the amount of gas will keep decreasing over time. If intermittent air use is involved, it is possible to calculate whether the time required to supply pressure of 2.5 MPa to the air tank within a specified period is sufficient. It is also possible to consider setting the average gas consumption at that time to be equal to the production volume. The key issue is to find a balance. The specific size of the buffer tank to be selected needs to be calculated based on the previous reference conditions. There’s no need to consider the critical aspect. No problem.
4000 per hour; if it operates continuously for 24 hours, there’s no need to worry about anything!
I’m sorry; I wasn’t clear enough. Nitrogen is used intermittently, at an average rate of 1,600 cubic meters per hour, with the lowest rates being around 300–400 cubic meters per hour. That’s why the owner is considering using a nitrogen generation unit capable of producing 2,400 cubic meters per hour, along with a nitrogen storage tank. In this setup, high-pressure nitrogen is compressed to 2.5 MPa and then reduced to 0.5 MPa using a pressure regulator. What I’d like to know is: for a nitrogen storage tank with a capacity of 100 cubic meters and a pressure of 2.5 MPa, what exactly is the increase in the amount of nitrogen available (expressed in cubic meters) after it’s regulated to 0.5 MPa via the pressure regulator? Because the critical compression ratio for nitrogen has been determined; in other words, the pressure ratio before and after the pressure regulator for nitrogen is around 1.6 to 1. If this ratio is higher, it is no longer possible to produce more nitrogen. Therefore, it is sufficient to compress the nitrogen to 0.9 MPa – there is no need to raise it to 2.5 MPa
This post was last edited by CHANGBAISHI on 2019-6-8 08:51. It’s fine for the total consumption to equal the total supply. For intermittent courage, it is necessary to install a gas storage tank, and this requires taking into account the maximum flow rate during intermittent gas use. The larger the set capacity, the lower the pressure; the smaller the capacity, the higher the pressure stored. Comprehensive assessment. Of course, ignoring investment costs, the larger, the better. The stability of the production equipment will be better.
I just want to ask: when using a nitrogen compressor to increase the pressure to 2.5 MPa and feed it into the nitrogen storage tank, and then using a pressure regulator to reduce the pressure to 0.5 MPa, what is the amount of loss that occurs?
I haven’t done the calculations specifically; I’m just a makeshift chemist, so please forgive me.
Because the technician who showed me how to do this told me that nitrogen at 2.5 MPa in a volume of 100 cubic meters can be adjusted to 0.5 MPa in the same volume of 100 cubic meters; in other words, 2.5 MPa is changed to 0.5 MPa for that 100 cubic meters volume. I think when I question her, she gets very upset and says, \"Then you decide for yourself.\" I searched the Internet for information on control valves used in pipelines, and it was stated that after the control valve is adjusted, the flow rate through the same pipeline remains constant; it’s not exactly equal to something else
This question is actually very simple, and the calculation isn’t difficult either. I recommend the book \"Principles of Chemical Engineering\"; it contains that information. It seems like you’re not in the design field; if that’s the case, then discussing this issue is really pointless. If one wants to figure out this problem, the first step is to find its entry point. It becomes clear if calculated using the gas equation. The (volumetric) flow rate, pressure, and temperature before the valve are equal to those after the valve. When calculating, both temperature and pressure should be converted to absolute values. Don’t forget that the local atmospheric pressure is also important to consider in the calculations. I haven’t used this for a long time; it’s best to refer to a book, as it should be easy to understand. This is going into more detail. I belong to the knockoff version of the randomly stir-fried soup; based on the data you mentioned, there are obviously problems. I’m not sure whether you didn’t understand what your instructor meant, or if that’s indeed the case; it seems that there’s a missing element here – whether to use the volume under pressure conditions, or to calculate it using the gas law.
That equation P1V1/T1=P2V2/T2 isn’t very applicable here, as T1 and T2 are based on absolute temperature; moreover, the operation of a pressure reducing valve inevitably results in a certain degree of loss