Thread Content
It is a long-distance pipeline over 100 kilometers long, carrying heated crude oil. The first station is equipped with two types of centrifugal pumps for transporting oil: one with a capacity of 65 m3/h and a head of 1000 meters, and another with a capacity of 46 m3/h and a head of 500 meters. There are a total of 4 valve chambers along the entire line; during normal operation, the operating pressure in valve chamber #4 is 1 MPa. The owner now wants to install a pump in Valve Room 2, with the aim of providing assistance during pigging operations. This is because there were instances in the past where pigs got stuck during pigging, forcing the owner to use a pump at Valve Room 4 to raise the pressure there to 6 MPa in order to get the pigs out. For the above reasons, the owner wants to install a screw pump in Valve Room 2#, and states that they are only concerned with pressure, not flow rate. (I think what they mean is during pipeline cleaning.) I recommend that the owner use a centrifugal pump; the viscosity of the oil at the transportation temperature is less than 10 mMa. Moreover, as the production volume is decreasing year by year, and in order to match the requirements of the first pumping station, it is recommended to use an export pump with a capacity of 46 m3/h and a head of 600 m. At its rated capacity, this pump can generate nearly 5 MPa in the 4# valve chamber, thereby meeting the owner’s target of 6 MPa. If a screw pump is used in valve chamber 2#, there may be a mismatch in transportation between the primary station and valve chamber 2#, as their performance curves are different. We were also surprised by this, but his reasoning was that when the cleaning tool causes a blockage, the pressure throughout the entire line remains the same; in other words, the pressure in valve chamber #4 is equal to the pressure at the outlet of the pump at the upstream station, which is the pump’s deadhead lift, as the flow rate is nearly 0 at that time. Thus, building a pumping station for this reason is not justified. It’s clear that this pumping station needs to be built. The key issue is choosing the right type of pump. In my opinion, centrifugal pumps are the best choice; however, the owner wants to use screw pumps. Apart from the fact that they don’t suit the first pumping station, I can’t think of any other good reasons for that. I hope fellow experts can offer some advice.