Given the diameters and design flow rates of several branches for the steam, how can we determine the diameter of the main steam pipe?
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Among the several branch pipes, 4 are DN40 and 1 is DN125; their flow rates are 80, 150, 150, 150, and 850 kg/h respectively. The operating pressure for all of them is 0.4 MPa, while the required operating pressure for the main pipe is 1.0 MPa. I’m hoping some experts can help me and teach me the method; I can do the calculations myself, or are there any tools that can be used for this?
Without knowing the pressure drop requirements and pipe length, only formula 7.1.4 of GB 50316-2000 can be used to calculate the pipe diameter. The pipe diameter, flow rate, and fluid density are all known; the average flow velocity is set at the minimum flow velocity recommended for the branch pipe.
I recommend a reference book for those working in the chemical industry: \"Principles of Chemical Engineering\".
Knowing the mass flow rate of each branch pipe, it is possible to calculate the mass flow rate of the main pipe. Since the operating pressure of the main pipe is 1.0 MPa while that of each branch pipe is 0.4 MPa, pressure reduction is necessary. The operating pressure of the main pipe before reduction is 1.0 MPa, and it becomes 0.4 MPa after reduction. The medium in question is steam; if it is saturated steam, the steam density at different pressures can be determined. If it is superheated steam, the steam temperature is also required in order to find the steam density. Given the mass flow rate and density of the main pipe, the volumetric flow rate of the main pipe before and after pressure reduction can be calculated. Based on the \"Guidelines for Selecting Pipe Sizes in Petrochemical Process Units\" SH/T3035-2007 or the \"Pipe Size Selection\" HG-T 20570.6-95, the pipe sizes for the main pipe before and after pressure reduction can be determined.
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This is easy to calculate, right? Are the several branches used simultaneously or separately? Just choose a recommended minimum flow rate in total, right?
A self-acting pressure reducing valve is installed on the main pipe to reduce the pressure to 0.4 MPa. The flow rate in the main pipe is equal to the sum of the flow rates in the branch pipes; the nominal diameter of the main pipe can be determined based on the minimum flow velocity
1 No details are provided in the question regarding the allowed variables, so there are various methods. 2. For example: The pressure at the end of each branch is as specified in the question, and the flow rate for each branch is also as given. Under the condition that all branches are in use simultaneously: 2.1. Calculate the pressure drop for each branch, using the length of each branch as a variable, so that the pressure at the starting point of each branch is 1.0 MPa. 2.2. Determine the diameter of the main pipe based on the total flow rate. 2.3. If the connection points of the various branches are close to each other, the resistance in the main pipe can be ignored, and it can be assumed that the pressure is the same throughout. 3. Different conditions require different methods; therefore, the person performing the calculations should first determine the operating conditions
I would like to ask whether there is a phase change between the main pipe and the branch pipes? If so, how is it calculated?