Improving Solar Power Efficiency Through Level and Flow Control | Magnetrol Blog

Magnetrol Nov 05, 2014 No Comments

Improving Solar Power Efficiency Through Level and Flow Control SEPTEMBER 2, 2014 / MAGNETROL Solar technologies use the sun’s energy to provide electricity, hot water, process heat and cooling. According to the U.S. Energy Information Administration, solar power presently provides less than 1% of U.S. energy needs, but this is expected to increase with the development of more efficient solar technologies. One way to enhance solar power efficiency is through the use of level and flow instrumentation to drive process improvement. TYPES OF SOLAR COLLECTORS Different solar collectors meet different energy needs. Passive solar designs capture the sun’s heat to provide space heating and light. Photovoltaic cells convert sunlight directly to electricity. Concentrating solar power systems focus sunlight with mirrors to create a high-intensity heat source, which then produces steam or mechanical power to run a generator that creates electricity. Flat-plate collectors absorb the sun’s heat directly into water or other fluids to provide hot water or space heating. SOLAR LEVEL AND FLOW APPLICATIONS Heat Transfer Fluid Storage: Large-scale solar collectors for electric power generation require a heat transfer fluid (water, thermal oils, or ionic liquids) to absorb the sun’s heat for generating steam. Arrays of mirrored panels convert the sun’s energy into +750° F (+399° C) thermal energy that’s hot enough to create steam for turbines. The mirrors focus sunlight onto pipes of heat transfer fluid that run along the mirror’s centerline. The fluid then boils water to produce steam. Thermal fluids also help provide hot water and heat. Thermal fluids are typically stored in pressurized tanks that require level monitoring. Recommended Continuous Level Technologies: Displacer Controller, Guided Wave Radar Recommended Point Level Technologies: External Cage Float Hot Water Storage: High-temperature solar water heaters provide energy-efficient hot water and heat for large industrial facilities. Thermal storage in buffer tanks provides interfaces between collector subsystems and energy-using systems. The preferred solar storage vessel is a vertical cylindrical tank designed for the maximum pressure of the supply water source, which may be as high as 150 psi. Recommended Continuous Level Technologies: Displacer Controller, Guided Wave Radar Recommended Point Level Technologies: External Cage Float Pump Protection: Flow switches protect pumps from damage due to leaks or if a valve is accidentally closed downstream. A flow switch will actuate an alarm and shut down the pump when flow drops below the minimum rate. Flow Alarm: Thermal Dispersion Flow Switch for High/Low Alarm, or Flow Switch

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Level Control Applications for Geothermal Power

Magnetrol Jul 07, 2014 No Comments

geothermal power example

BROCHURE :instrumentation for renewable energy

Geothermal reservoirs located deep underground provide powerful sources of heat energy. Drilling a geothermal well to a reservoir brings hot water and steam to the surface, where it is valued as a source of renewable energy. The three principal uses of geothermal power are electricity generation, geothermal heating and geothermal heat pumps. In these systems, there is a wide range of applications that require reliable level measurement and control for efficiency and safety.

GEOTHERMAL POWER GENERATION

Geothermal electricity can be produced at dry steam plants, flash steam plants and binary cycle plants. Dry steam plants use steam piped directly from a geothermal reservoir. Flash steam plants take high-pressure hot water and convert it to steam. As the water rises, the pressure is reduced and the water flashes to steam. Binary cycle plants take heat from the geothermal water and transfer it to an organic fluid (a butane or pentane hydrocarbon) with a low boiling point in a high-pressure heat exchanger known as a vaporizer. The heat transfer causes the second (or “binary”) liquid to turn to steam.

Geothermal heating is the direct use of geothermal heat for space and process heating applications. Industrial applications include zinc and gold mining, desalination, milk pasteurization and food dehydration.

Geothermal heat pumps use the Earth's constant temperatures to heat and cool buildings by transferring and removing heat into buildings according to seasonal needs.

Geothermal Vessels 2

GEOTHERMAL LEVEL APPLICATIONS

1. STEAM/BRINE SEPARATOR: To achieve better conditions for turbine operation, a reservoir’s steam and brine (salt water) is separated into streams where the brine water and particulate matter settle out and the steam vapors rise. The steam collects at the top of the separator where it is removed. Liquid level control modulates the amount of water that is drawn off. Recommended Continuous Level Technologies: Guided Wave Radar, Displacer Controller Recommended Point Level Technologies: External Cage Float, Thermal Dispersion

2. DEGASSER TANK: Geothermal hot water is often routed through a degasser – a large insulated tank equipped to remove organic gases and provide displacement with air or nitrogen. Degassing operations provide treatment by way of carbon adsorption, thermal/catalytic oxidization, combustion, vacuum induction or by a series of condensers. Recommended Continuous Level Technologies: Guided Wave Radar, Displacer Controller Recommended Point Level Technologies: External Cage Float, Thermal Dispersion

3. WATER STORAGE TANK: Water tanks include those for heated water, cooling water, and wastewater. Direct heat use applications require heated water storage. Spent geothermal fluids with high concentrations of chemicals are stored prior to treatment and reinjection into the reservoir. Hot water can be cooled in special storage tanks to avoid modifying the ecosystem of natural bodies of water prior to reinjection. Recommended Continuous Level Technologies: Guided Wave Radar, Displacer Controller, Pulse Burst Radar (Through Air), Ultrasonic Recommended Point Level Technologies: Float Actuated, Ultrasonic

4. FLASH TANK: Hot water from the geothermal well enters a flash tank where the reduced pressure causes the water to boil rapidly, or "flash" into vapor. Water that remains liquid in the tank is returned to the groundwater pump to be forced down into the reservoir again. The vapor from the flash tank drives the steam turbine. Recommended Continuous Level Technologies: Guided Wave Radar Recommended Point Level Technologies: Displacer Switch, Thermal Dispersion

VAPORIZER: In these special heat exchangers, the geothermal fluid heats and vaporizes a secondary “binary” fluid, which is typically an organic liquid with a low boiling point. The organic vapor drives the turbine. The level of water in the tank must be monitored. Recommended Continuous Level Technologies: Guided Wave Radar, Displacer Controller Recommended Point Level Technologies: External Cage Float, Ultrasonic

LEVEL INSTRUMENTATION FOR GEOTHERMAL POWER APPLICATIONS Screen Shot 2014 06 13 at 7.37.51 AM

Displacer Level Transmitter Technology Offers Advantages Over Torque Tubes

Magnetrol Jun 03, 2014 No Comments
digital e3 modulevelTorque tube instrumentation has been a common solution for level control applications. However, many processing plants are converting to a displacer level transmitter, which uses range spring technology, for more reliable level measurement and control. Displacer level transmitters, such as the Magnetrol® E3 Modulevel® linear variable differential transformer (LVDT) transmitter, feature greater output stability, structural integrity and ease of installation, compared to torque tubes. The following outlines why displacer level transmitter technology offers an excellent alternative to existing torque tube units.   Principle of Operation E3 MODULEVEL electronic level transmitters are advanced, intrinsically safe, two-wire instruments that utilize a simple buoyancy principle to detect and convert liquid level changes into a stable 4-20 mA output signal. The linkage between the level sensing element and output electronics greatly simplifies mechanical design and construction. Liquid level change acts upon the spring supported displacer causing vertical motion of a core within a linear variable differential transformer (LVDT). The enclosing tube acts as a static isolation barrier between the LVDT and the process media. As the core position changes with liquid level, voltages are induced in the secondary winding of the LVDT. These signals are processed in the electronic circuitry and used to control the current in the 4-20 mA output current loop. Benefits Over Torque Tubes As noted above, reliable output, structural integrity and ease of use are primary reasons displacer level transmitter technology outperforms torque tubes. Range spring technology dampens the effects of vibration and features a longer travel zone, yielding an output signal that is four times more stable than torque tubes. Range spring movement is free of wear and friction, unlike torque tubes, whose twisting motion causes friction buildup and fatigue failure. Displacer level transmitters are easier to install than torque tubes, and don’t require shutdown of process lines. Replacing Existing Torque Tubes I&C technicians who want the benefits of a range spring controller can reduce installation costs by not having to field pipe new cages. The existing torque tube cage may be used, based on the following considerations: Torque tube units should have side/bottom or side/side process piping connections. It is not possible to utilize the existing cage on a top-in/bottom-out torque tube cage. By replacing the entire unit with a complete MODULEVEL device equipped with top-in/bottom-out process piping cage connections, the process piping connection can be matched. If the existing cage has a vent connection piped into the top of the torque tube cage, it will also have to be repiped to a tee. The tee will have to be added to the top process connection on the cage side of the isolation valve or to a vent connection. The displacer length must be the same or shorter than the existing torque tube displacer. Torque tube displacers are larger in diameter than the MODULEVEL and manufactured in the same standard spans. By matching the torque tube chamber parting flange size, pressure, material, bolt circle, and the displacer span, a MODULEVEL unit can be mounted on the existing chamber. via Displacer Level Transmitter Technology Offers Advantages Over Torque Tubes.