A multi-stage fluid pump system can include a first stage configured to provide a first pressure and a second stage configured to provide a second pressure. The pump system can be configured to prevent output of the second stage in a first stage mode such that only the first pressure is output from the first stage and second stage and to allow output of the second stage in a multi-stage mode such that there is a combined pressure output from the first stage and the second stage.

A system and method for operating centrifugal pumps related to net positive suction head (NPSH), including identifying a group of centrifugal pumps and deriving an equation for the group based on manufacturer data of the centrifugal pumps collectively in the group, the equation correlating NPSH required (NPSHr) with flowrate of pumped fluid, wherein the manufacturer data includes NPSHr for each centrifugal pump of the group as a function of the flowrate of the pumped fluid. The technique includes specifying a NPSH margin for NPSH available (NPSHa) above the NPSHr.

A method for evacuating a process space by initially evacuating the process space to a pressure limit value using two compressors operated in parallel, and on reaching or undershooting the pressure limit value, the process space is subsequently evacuated using the two compressors operated in series.

A fuel pump system, comprising an inlet line and a motorized pump, a first selector valve in fluid communication with an inlet line at a first inlet port and in fluid communication with the motorized pump outlet via a first outlet branch at a second inlet port to receive fuel from the motorized pump outlet. The system can also include a main fuel pump in fluid communication with the first selector valve and a second selector valve, wherein the second selector valve can be in fluid communication with the main fuel pump and in fluid communication with the motorized pump outlet.

A method for determining a set of optimal operating parameters for a pumping plant that pumps a fluid medium by a set of multiple pumps connected in parallel includes: determining, from the set of pumps, a set of possible scenarios, each scenario indicating, for each pump in the set, whether the pump is running or not running; optimizing, for each scenario, a set of operating parameters including operating parameters of the pumps that are running according to the respective scenario so that all running pumps together bring a given input mass flow of the medium from a given input pressure to a given output pressure while minimizing a total power consumption of all running pumps, and assigning the found minimum power consumption and the corresponding optimal operating parameters to the respective scenario; and determining, from the set of scenarios, the scenario with a lowest power consumption.

Apparatus, including a pump system controller, features a signal processor or processing module configured at least to: receive signaling containing information about pump differential pressure, flow rate and corresponding power data at motor maximum speed published by pump manufacturers, as well as instant motor power and speed, for a system of pumps arranged in a multiple pump configuration; and determine corresponding signaling containing information about instant pump differential pressure and flow rate for the system of pumps arranged in the multiple pump configuration using a combined affinity equation and numerical interpolation algorithm, based upon the signaling received.

A signal processor receives signaling containing information about flow rates from sensorless converters in zone circulators in heating/cooling zones controlled by temperature sensors in a hydronic heating system in order to derive an adaptive pressure set point to meet the flow rates requested by the heating/cooling zones using an adaptive system and flow control curve equation, the signaling containing information about total flow rates requested by the zone circulators; determines desired pump speeds for the zone circulators to meet temperature requirements in heat zones; provides corresponding signaling containing information about the desired pump speeds; and/or determines the adaptive pump control curve equation based upon an adaptive system curve and as a moving maximum system flow rate depending on an adaptive pressure set point, a system flow rate requested by temperature loads, a minimum pressure at no flow, a control curve setting parameter, and an adaptive moving maximum flow and pressure.

Aspects of the invention generally provide a heat engine system and a method for activating a turbopump within the heat engine system during a start-up process. The heat engine system utilizes a working fluid circulated within a working fluid circuit for capturing thermal energy. In one exemplary aspect, a start-up process for a turbopump in the heat engine system is provided such that the turbopump achieves self-sustained operation in a supercritical Rankine cycle. Bypass and check valves of a start pump and the turbopump, a drive turbine throttle valve, and other valves, lines, or pumps within the working fluid circuit are controlled during the turbopump start-up process. A process control system may utilize advanced control techniques of the control sequence to provide a successful start-up process of the turbopump without over pressurizing the working fluid circuit or damaging the turbopump via low bearing pressure.

A circulation pump assembly (22) includes an electrical drive motor (10) and an electronic control device (12) controlling the drive motor (10). The control device (12) is configured for the speed control of the drive motor (10) according to a control schema (I, II, III). The control device (12) includes a detection function (42) which is configured to detect a condition variable representing an operating condition, from a parallel flow path (16, 18, 20) with a second circulation pump assembly (22). The control device (12) is also configured such that it can change the control schema (I, II, III) on the basis of a condition variable detected by the detection function (42). Further an arrangement of at least two such circulation pump assemblies (22) and a method for the control of such two circulation pump assemblies (22) are provided.

A liquefied gas unloading and deep evacuation system may more quickly, more efficiently and more completely unload liquefied gases from transport tanks, such as rail cars, into stationary storage tanks or into truck tanks. The system may utilize a two stage compressor, an electric motor, a variable frequency drive, a four way valve, a three way valve, a two way valve, a programmable logic controller based control system and pressure and temperature transmitters. The valving enables deep evacuation of the transport or supply tank to more completely empty the transport tank. The programmable logic controller and variable speed drive may be used to variably control the speed of the two stage compressor so that the system may be running as fast as possible during changes in ambient temperature and/or different stages of offloading the liquefied gases without exceeding the compressor's horsepower limit.