Method of filtering pump noise
A method of filtering out pressure noise generated by one or more piston pumps, where each pump is connected to a common downstream piping system, and where the discharge pressure is measured by a pressure sensitive gauge, wherein the instantaneous angular position(s) of the pump(s)' crankshaft or actuating cam is/are measured simultaneously with the discharge pressure and used as fundamental variables in an adaptive mathematical noise model.
1. A method of filtering out pressure noise generated by one or more piston pumps, where each pump is connected to a common downstream piping system, and where the discharge pressure is measured by a pressure sensitive gauge,
wherein the instantaneous angular position(s) of the pump(s)' crankshaft or actuating cam is/are measured simultaneously with the discharge pressure and used as fundamental variables in an adaptive mathematical noise model, and
wherein the adaptive mathematical noise model comprises a theoretical part and an empirical part, the theoretical part representing the expected flow and pressure fluctuations that, for each new pressure measurement, are calculated on the basis of the associated measured angular positions and knowledge of piston speeds, valve characteristics, the compressibility of the fluid and the geometry of the downstream piping system, and the empirical part, which describes discrepancies between measured and expected noise, being calculated as frequently as the theoretical one but being represented by periodically updated model parameters.
2. A method in accordance with claim 1 , wherein the adaptive mathematical noise model is periodically updated by a generalised Fourier analysis using the angular position of the pump shafts as fundamental independent variables in the Fourier integrals and transfer functions describing the changes in pressure amplitude and phase as functions of the frequency of certain pump generated flow rate variations.
3. A method in accordance with claim 1 , wherein the model parameters in the empirical adaptive mathematical noise model are periodically updated, e.g. upon each completed revolution, also while the pump speed changes and when the telemetry signals are present in the measured common discharge pressure.
4. A method in accordance with claim 1 , wherein the two parts of the noise model, represented by complex Fourier series of flow components for each pump, are transformed into functions that show theoretical and empirical flow rates as a function of the angular position of the pumps, and which can therefore be used as diagnostic tools for e.g. quantifying and locating leaks in valves or pistons.
5. A method in accordance with claim 1 , wherein the two parts of the noise model, represented by complex Fourier series of flow components for each pump, are transformed into spectra that show theoretical and empirical flow rates as a function of normalized pump frequencies, and which can therefore be used as diagnostic tools for e.g. quantifying and locating leaks in valves or pistons.