Process Status Evaluating Tool

Process Status Evaluating Tool: How can the pump process be evaluated pumping water?

De Bie, M.

Slager, K. (mentor)
Talmon, A.M. (mentor)
Van Rhee, C. (mentor)

Mechanical, Maritime and Materials Engineering

Offshore & dredging engineering

2017-01-31

Damen Dredging Equipment (DDE) has a quest to make their cutter suction dredger (CSD) and their DOP pump operable by everyone for every slurry type at the correct working point every time. To complete this quest, first a process status evaluating tool has to be developed which replaces the visual wear inspection. This thesis is the first step in developing this tool, its research question hence is "How can the pump process status be evaluated pumping water?" To answer this question, first a literature study about a centrifugal pumpis done (chapter 1) to understand the working principle of a centrifugal dredge pump. Next, the wear locations in a centrifugal dredge pump are going to be examined (chapter 3) after a small wear definition introduction (chapter 2). From the wear locations found, the ones that are expected to have the most influence on the pump performance (head H and efficiency ´) are further researched in this thesis. These locations are: the axial gap and the inner impeller diameter. For the axial gap, data was already available due to previous research at DDE [1]. The data for the influence of the inner impeller diameter change is created by own experiments on the sediment transport circuit at DDE, these experiments are explained in chapter 5. Also another conditionmonitoring option (not only the influence of the pump parameters) is researched after different possibilities were investigated (chapter 4). This method is the vibration analysis of the pump and is used to see whether or not the influence of wear on the pump can bemonitored. This wear is created by pumping a slurry (sand-water) mixture through the sediment transport circuit while using casted steel for the impeller and wear plate (it would take a lot of time to create wear on the original nihard impeller and wear plate). The data for the axial gap, inner impeller diameter and vibrational analysis is explained in chapter 6. The research question can be answered in two parts: the influence on the pump parameters and the vibration analysis of the pump. The data analysis of the influence of the axial gap on the pump parameters (section 6.1) shows that it is possible to indicate whether the axial gap is small or large (2mm vs 11mm) by using a trialand- error method proposed in this study. The data analysis of the inner impeller diameter (section 6.2) shows two methods to calculate the inner diameter increase from the data obtained during the own experiments. Both methods are based on the change of the velocity triangles resulting in an extended version of the pump affinity law for head. The NPSH could not be measured decent, so no model is obtained for this. The last part to answer the research question is the vibrational analysis (in radial, axial and tangential direction). The BEP point can be found using the vibrational analysis (lower vibration level). Also cavitation in the pump is detected by the vibrational analysis (high scattering of vibrational data points). A last thing that can be seen is when the pump operates left from the BEP, the axial vibration level increases a lot. All the findings in chapter 6 should be tested for not only the DOP250, but for a various range of pumps and settings. This to conclude if the findings are applicable for every pump, or only for the DOP250 in setting used in the sediment transport circuit.

http://resolver.tudelft.nl/uuid:67979437-ebf3-436a-98c7-8868344447b0

2018-01-31

Student theses

master thesis

(c) 2017 M.de Bie