Flow Booster Research Articles

How do the influent COD/Nitrogen and internal recirculation ratios affect the oxidation ditch type pre-anoxic landfill leachate treatment?

A design-based dynamic simulation tool was developed to evaluate the effects of altered operation conditions on the performance of a landfill leachate treating pre-anoxic oxidation ditch folowed by external ultra filtration and nano filtration membranesby using the actual influent data and operational constants collected for 18 months. In the summer of 2017, the MBR suffered from reduced membrane fluxes due to deterioration of activated sludge flocs after the failure of flow booster providing the internal circulation and decreasing influent C/N ratio. Although two external pumps were activated in place of the broken flow booster, the required internal recirculation ratio (IR) predicted by the simulation could not be provided. It was concluded that due to low IR, the activated sludge retaining longer in the anoxic tank lost its floc integrity and caused decreased membrane fluxes. Simulation findings also showed that if the COD/N ratio drops below 4.8, no matter how high the IR is, it is unlikely to achieve a NOx-N concentration below 30 mg/l in the effluent. On the other hand, contrary to expectations, both the actual and estimated nitrification efficiencies were very high due to the moderately high temperature (>20 °C) and DO (2–3 mg/l) values in the aerobic basin.

Theoretical and Experimental Studies of a Digital Flow Booster Operating at High Pressures and Flow Rates

The switched inertance hydraulic converter (SIHC) is a new technology providing an alternative to conventional proportional or servo-valve-controlled systems in the area of fluid power. SIHCs can adjust or control flow and pressure by means of using digital control signals that do not rely on throttling the flow and dissipation of power, and provide hydraulic systems with high-energy efficiency, flexible control, and insensitivity to contamination. In this article, the analytical models of an SIHC in a three-port flow-booster configuration were used and validated at high operating pressure, with the low- and high-pressure supplies of 30 and 90 bar and a high delivery flow rate of 21 L/min. The system dynamics, flow responses, and power consumption were investigated and theoretically and experimentally validated. Results were compared to previous results achieved using low operating pressures, where low- and high-pressure supplies were 20 and 30 bar, and the delivery flow rate was 7 L/min. We concluded that the analytical models could effectively predict SIHC performance, and higher operating pressures and flow rates could result in system uncertainties that need to be understood well. As high operating pressure or flow rate is a common requirement in hydraulic systems, this constitutes an important contribution to the development of newly switched inertance hydraulic converters and the improvement of fluid-power energy efficiency.

Lab-scale Evaluation of Spiral Vortex Artificial Circulation

When phosphorus and nitrogen concentrations are high in lakes and reservoirs, enough for algae to grow, algal bloom prevention needs to be approached by circulation of stagnant water. A new circulation technology ‘Spiral vortex artificial circulation’ was developed that transports water to the surface without any hose and also provides sufficient oxygen as the water circulates. Artificial thermal and dissolved oxygen stratification was created in a water tank, and thermometers and DO meters were placed at each layer to evaluate the technology’s efficiency by comparing how fast the stratification broke. Two types of booster were used: a flow booster which promotes thorough mixing and a 12 cm flat round booster that protects the bottom of water column from disturbing, yet circulates the surface. Impeller speed was set at 60 rpm and 180 rpm to compare speed difference thus total of four experiments were conducted. The stratified water was completely mixed in two experiments with flow booster. However when 12 cm flat round booster was used at 60 rpm, even after 100 minutes of operation the stratification was not broken whereas it took 75 minutes at 180 rpm. The same or similar settings can be applied in situ without disturbing the benthic zone; if not, nutrients could be released to water bodies which might lead serious eutrophication. The further technology evaluation is in progress for improving its algal bloom suppression and energy efficiency since all technologies required to be environmentally sustainable.

Wind or water turbine power augmentation using the system of guiding surfaces

As fluid flows through a conventional wind or hydro turbine, it slows from losing energy to extraction from a turbine and spreads out to a wider area. This results in a loss of turbine efficiency. In order to exploit wind or water flow power more effectively, it was suggested to place the turbine inside a system of specially designed airfoils (‘a flow booster’). One part of the booster (‘a nozzle’) improves the turbine performance by speeding up the flow acting on the turbine blades. The other part of the accelerating system (‘a diffuser’) creates a field of low pressure behind the turbine which helps to draw more mass flow to the turbine and avoid the loss of efficiency due to flow deceleration. The flow booster accumulates the kinetic energy of the flow (e.g. river flow or wind) in a small volume where the smaller turbine can be installed. Another possible application of the booster could be the improvement of wind turbine efficiency during low wind period. The present paper also discusses the possibility of kinetic energy accumulation by the use of several accelerating systems of different sizes—the smaller one can be installed inside the bigger one. It helps to accumulate even more kinetic energy on the turbine blades. We call this method the kinetic energy cumulation. Lab and field experiments and CFD simulations of shrouded turbine demonstrate significant increase in velocity in comparison of those for conventional (bare) turbines.

Experimental Investigation of a Switched Inertance Hydraulic System With a High-Speed Rotary Valve

This paper reports on experimental investigations of a switched inertance hydraulic system (SIHS), which is designed to control the flow and pressure of a hydraulic supply. The switched system basically consists of a switching element, an inductance (inertance), and a capacitance. Two basic modes, a flow booster and a pressure booster, can be configured in a three-port SIHS. It is capable of boosting the pressure or flow with a corresponding drop in flow or pressure, respectively. This technique makes use of the inherent reactive behavior of hydraulic components. A high-speed rotary valve is used to provide sufficiently high switching frequency and to minimize the pressure and flow loss at the valve orifice, and a small diameter tube is used to provide an inductive effect. In this paper, a flow booster is introduced as the switched system for investigation. The measured steady-state and dynamic characteristics of the rotary valve are presented, and the dynamics characteristics of the flow booster are investigated in terms of pressure loss, flow loss, and system efficiency. The speed of sound is measured by analysis of the measured dynamic pressures in the inertance tube. A detailed analytical model of an SIHS is applied to analyze the experimental results. Experimental results on a flow booster rig show a very promising performance for the SIHS.

Automatic cleaning system of sample preparation of flue gas tester

It is shown a detailed description of the operation of the automatic cleaning at different modes and levels of concentration of dust and gas stream pollution of flue gas. The basis of an automatic cleaning system of dust filters before gas analyzers based on the principle of a closed system of automatic control. The system constantly compares the real current flow rate with a fixed current pre-entered in the control unit. The control unit sends a signal to the switching system of solenoid valves when reducing the flow of the sample, due to contamination (clogging) of filters below a fixed level and with the help of flow booster begins to reverse blowing of dust filter from dust in the chimney. During investigation it is found that the best operation mode of system actuation is a 25-30 % decrease in the expense of the nominal value of the primary sample flow while clean filter. Another important feature of the system is the choice of performance and power of flow boosters for blowdown. The power of flow booster was 1,5-2,0 kW during investigations on the smokestacks of coal boilers, TPC with the dust concentration of 120-150 mg/m 3 with ensuring a flow rate of smoke samples in the range of 8-10 l/min. The proposed system is simple in construction, does not require a significant investment for its implementation and provides automatic cleaning of dust filters without operator. Automatic cleaning of filter dust is recommended for stationary systems for monitoring the concentration of toxic components of flue gases for industry, energy, cement, brick and asphalt concrete plants, everywhere where the treatment and control of flue gas is carried out by gas analyzers.

Theoretical and experimental studies of a switched inertance hydraulic system including switching transition dynamics, non-linearity and leakage

This article reports on theoretical and experimental investigations of a switched inertance device, which is designed to control the flow and pressure of a hydraulic supply. The device basically consists of a switching element, an inductance and a capacitance. It is able to boost the pressure or flow with a corresponding drop in flow or pressure, respectively, analogous to a hydraulic transformer. In this article, an enhanced analytical distributed parameter model in the frequency domain, which includes the effect of switching transition, non-linearity and leakage of the valve, is proposed and validated by simulation and experiments. A flow booster test rig is studied as a typical system. Simulated and experimental results show good performance, and accurate estimation of system pressure and dynamic flowrate can be obtained using the enhanced analytical model. The model is very effective for understanding, analysing and optimising the characteristics and performance of a switched inertance device. It can also be used to aid in the design of a switched inertance hydraulic system.

Active control of pressure pulsation in a switched inertance hydraulic system

The nature of digital hydraulic systems may cause severe pressure pulsation problems. For example, switched inertance hydraulic systems can be used to adjust or control flow and pressure by a means that does not rely on dissipation of power, but they have noise problems because of the pulsed nature of the flow. An effective method to reduce the noise is needed that does not impair the system performance and efficiency. This article reports on an initial investigation of an active attenuator for pressure pulsation cancellation in a switched inertance hydraulic system. Using the designed noise attenuator, the pressure pulsation can be decreased effectively by superimposing an anti-phase control signal. A high-performance piezoelectric valve was selected and used as the secondary path actuator in terms of its fast response and wide bandwidth. Adaptive notch filters with the filtered-X least mean square algorithm were applied for pressure pulsation attenuation, while a frequency-domain least mean square filter was used for secondary path identification. A ‘switched inertance hydraulic system’ in a flow booster configuration was used as the test rig. Experimental results show that excellent cancellation was achieved using the proposed method, which has several advantages over passive noise control systems, being effective for a wide range of frequencies without impairing the system’s dynamic response. The method is a very promising solution for pressure pulsation cancellation in hydraulic systems with severe noise or vibration problems.