DESIGN CURRENT DENSITY IMPACT ON COST AND RELIABILITY OF SUPERCONDUCTING MAGNET SYSTEMS FOR EARLY COMMERCIAL MHD POWER PLANTS

Control rod drive mechanism is one of the key main components in nuclear power plants and serves in harsh environments such as high temperature, high pressure and nuclear radiation. In order to ensure the service life and to prevent biting when assembling, some of the threads of control rod drive mechanism need to be chromium plated. In view of the high demands of the same chromium plating thickness on all surfaces of the threads of control rod drive mechanism of nuclear power and non-uniformity in chromium plating thickness of threads due to poor throwing power of chromium plating solution, five representative kinds of threads of control rod drive mechanism were selected and the plating thickness change of the root diameter, pitch diameter and crest diameter of threads was studied in this paper by means of depositing different thickness chromium coating on the surface of threads. The experimental results show that thicker coating is deposited on the crest of thread because of high current density and thinner coating is deposited on the root of thread because of low current density, which can provide reference for specification of chromium plating thickness of thread products of control rod drive mechanism.

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Electrochemical treatment of raw water for thermal power plants requirements

Association of Arab Universities Journal of Engineering Sciences ◽

10.33261/jaaru.2020.27.2.013 ◽

2020 ◽

Vol 27 (2) ◽

pp. 147-153

Author(s):

Ali Ali ◽

Haitham Shaheen ◽

Mesaa Shash ◽

Bashar Zedan

Keyword(s):

Current Density ◽

Power Plants ◽

Thermal Power ◽

Electrochemical Treatment ◽

Total Dissolved Solids ◽

Optimum Conditions ◽

Dissolved Solids ◽

Batch Mode ◽

Nacl Concentration ◽

Initial Ph

In this research electrochemical treatment was used to treat Al-Sin water that feed Banias thermal station boilers for generate electricity. The effect of the operating parameters such as type of electrodes, initial pH,inter electrode distance, electrolysis time and current density on the effectiveness of electrochemical processing were studied in reducing the concentration of total dissolved solids (TDS), NaCl concentration, and electrical conductivity. The experiments were carried out in a batch mode. Results revealed that in the optimum conditions (current density=500A/m2, distance between electrodes =10mm) the total dissolved solids, conductivity, and NaCl concentration were reduced by (97%), (94%) and (92%) respectively after one hour of treatment process by using aluminum electrodes.

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25 TESLA HTS MAGNET INSERT COIL IN ZERO BOIL OFF CRYOSTAT

International Journal of Modern Physics B ◽

10.1142/s0217979209062426 ◽

2009 ◽

Vol 23 (12n13) ◽

pp. 2842-2845

Author(s):

J. GOOD ◽

D. BRACANOVIC

Keyword(s):

Liquid Helium ◽

Critical Current ◽

Current Density ◽

Superconducting Magnets ◽

Superconducting Magnet ◽

Cooling Power ◽

Zero Field ◽

Magnet System ◽

Flux Flow ◽

2Nd Generation

The development of High Temperature Superconductors (HTS) conductors makes it possible to build very high field superconducting magnets up to at least 25 T. Previously, the only way to obtain a steady field of 25 T for research would be to use water cooled copper solenoids. To achieve 25 T in a 50 mm working space would require about 10 MW of power with a large water cooling plant to carry away the heat. With such high powers involved it is difficult to have a stable and quiet magnetic field environment in which to make sensitive measurements such as NMR. Both capital and operating costs are high so few such facilities exist worldwide. This makes a superconducting magnet of 25 T a very attractive proposition. Figure 1 shows that the critical current of HTS as compared to NbTi and NbSn . The latter can be used up to a limit of about 20 T at 4.2 K. The HTS on the other hand shows the potential of much higher fields. The two main issues in magnet design are the maximum critical current and the maximum stress that a conductor or coil structure can support. For the inner sections of the coil the forces are modest but as the diameter increases towards the outside of the coil hoop stress becomes the dominant issue. [Formula: see text] Cryogenic has built a magnet system with first generation BSCCO conductor. It is designed to run at 4.2 K. It has a three section design, two of conventional superconductor and one of HTS. • The outer winding is made from NbTi giving a field of 9 T, in a bore of 225 mm. The coil is made from 21 km of NbTi wire graded from 1 to 0.6 mm diameter. • A middle coil of NbSn bronze route conductor providing a field of 14 T in 140 mm diameter. • An inner set of HTS coils. These are in the form of 3 coaxial windings made from silver matrix BSCCO conductor supplied by American Superconductor. This conductor has a critical current of 100 A at 77 K in zero field. At 4 K in low field the current is very much higher. The set of three BSCCO windings has a gauss per amp of 157 and when run on its own at a current of 300 A provides a field of 4.7 T, although currents above 275 A begin to show significant resistive losses in the conductor. The inner BSCCO coils are separately powered from the outer magnet. In a test of the full magnet system the BSCCO coil is ramped up at various background fields up to 13 T. The resulting voltage loss across the BSCCO is shown in Fig. 2. This test shows that the BSCCO conductor can operate up to 275 A quite successfully independent of the background field with just a slight increase in resistive losses presumably from the joints between conductor being magneto-resistive or due to flux flow in the conductor. [Formula: see text] Since the BSCCO coils were made new 2nd generation conductors have become available made from thin films of YBCO on a stainless steel backing. These have a much higher effective current density. A 4 mm wide tape of BSCCO is 0.4 mm thick but carries a similar current to an YBCO tape of 0.01 mm or even 0.05 mm thickness. Table 1 shows the properties of different conductors compared. Interestingly the conductors are not just higher current density but also more flexible and stronger in tension. [Formula: see text] A new coil has now been produced from 0.1 mm Super Power material of a size that can fit inside the existing winding so that the combination can produce above 6 T providing a total field of 20 T at 4.2 K in a working bore of 38 mm. Now that the new 2nd generation YBCO based conductors have become available it is intended to exchange the BSCCO coils for YBCO windings which will allow this magnet to operate at much higher fields of up to 25 T. At this field it will be the highest field superconducting magnet worldwide. The magnet is housed in a liquid helium cryostat. To reduce helium consumption a powerful 2nd stage cryocooler is fitted to the cryostat. The first stage cools a shield around the liquid helium to 45 K. The second stage has a cooling power of 1.5 W at 4.2 K and is used to recondense helium gas evolved from the magnet. In operation, with no current in the leads to the cryocooler it is able to condense more gas than that evolved from the cryostat so the liquid helium level will increase with time. Except at the highest currents the cryostat is a zero loss magnet system. A cross section of cryostat and magnet is show in Fig 3. [Formula: see text] The power required for the cryocooler is 6.5 kW while that for the magnet power supplies and ancillary electronics is 2 kW giving a combined power requirement of 8.5 kW. This compares very favourably with the typical value of 10 MW required by a water cooled copper solenoid to achieve the same field. Note from Publisher: This article contains the abstract only.

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Optimum conditions of stabilizer ratio and critical current margin for maximizing the current density of a tightly-wound superconducting magnet

IEEE Transactions on Applied Superconductivity ◽

10.1109/77.233761 ◽

1993 ◽

Vol 3 (1) ◽

pp. 539-542 ◽

Cited By ~ 1

Author(s):

T. Satow

Keyword(s):

Critical Current ◽

Current Density ◽

Superconducting Magnet ◽

Optimum Conditions

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Simultaneous removal of Ni(II) and fluoride from a real flue gas desulfurization wastewater by electrocoagulation using Fe/C/Al electrode

Journal of Water Reuse and Desalination ◽

10.2166/wrd.2016.010 ◽

2016 ◽

Vol 7 (3) ◽

pp. 288-297 ◽

Cited By ~ 8

Author(s):

Shinian Liu ◽

Xiaokun Ye ◽

Kuang He ◽

Yuancai Chen ◽

Yongyou Hu

Keyword(s):

Energy Consumption ◽

Current Density ◽

Flue Gas ◽

Power Plants ◽

Oxygen Demand ◽

Flue Gas Desulfurization ◽

Fluoride Removal ◽

Nickel Ions ◽

Electrode Distance ◽

Anode Electrode

Large amounts of anions and heavy metals coexist in flue gas desulfurization (FGD) wastewater originating from coal-fired power plants, which cause serious environmental pollution. Electrocoagulation (EC) with Fe/C/Al hybrid electrodes was investigated for the separation of fluoride and nickel ions from a FGD wastewater. The study mainly focused on the technology parameters including anode electrode type, time, inter-electrode distance (5–40 mm), current density (1.88–6.25 mA/cm2) and initial pH (4–10). The results showed that favorable nickel and fluoride removal were obtained by increasing the time and current density, but this led to an increase in energy consumption. Eighty-six percent of fluoride and 98% of Ni(II) were removed by conducting the Fe/C/Al EC with a current density of 5.00 mA/cm2 and inter-electrode distance of 5 mm at pH 4 for 25 min and energy consumption was 1.33 kWh/m3. Concomitant pollutants also achieved excellent treatment efficiency. The Hg, Mn, Pb, Cd, Cu, SS and chemical oxygen demand were reduced by 90%, 89%, 92%, 88%, 98%, 99.9% and 89%, respectively, which met stringent environmental regulations.

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