Steam loop, high-temperature

ORNL small-break LOCA tests Experimental investigation of heat transfer and reflood analysis was made under conditions similar to those expected in a small-break LOCA. These tests were performed in a large, high-pressure, electrically heated test loop of the ORNL Thermal Hydraulic Test Facility. The analysis utilized a heat transfer model that accounts for forced convection and thermal radiation to steam. The results consist of a high-pressure, high-temperature database of experimental heat transfer coefficients and local fluid conditions. 

In all cases steam is present as the main ballast. The role of steam is to decrease the concentration of isobutane and oxygen in the recycle loop and thus keep the reactant mixture outside the flammability region. Water can be easily separated from the other components of the effluent stream, and also plays a positive role in the catalytic performance of POMs. It is also possible that the presence of water favors the surface reconstruction of the Keggin stmcture, which decomposes during the reaction at high temperature, and also promotes desorption of methacrylic acid, saving it from unselective consecutive reactions. 

If an operator saw this problem developing, he would switch the temperature loop into manual and cut back on the steam flow. The control system in Fig. 8,4fl will perform this "override control automatically. The low selector (LS) sends to the steam valve the lower of the two signals. If the steam valve is air-to-open, the valve will be pinched back by cither high temperature (through the reverse-acting temperature controller) or by low base level (through the low-base-level override controller). 

High Pressure Valves used for pressures nominally above 760 bar (11,000 psi, pressures above ANSI Class 4500) are often custom-designed for specific applications. Normally, these valves are of the plug type and use sped ally hardened plug and seat assemblies. Internal surfaces are polished, and internal corners and intersecting bores are smoothed to reduce high localized stresses in the valve body. Steam loops in the valve body are available to raise the body temperature to increase ductility and impact strength of the body material. 

The Exergy process. In this process, whole seeds or flakes are suspended in superheated steam at high pressure when they are moved turbulently through a heated pipe loop. This heat treatment requires only a few seconds to achieve the temperature needed to inactivate enzymes (68). In the case of canola, whole seed or flakes can be treated this way. Heat treatment of whole seeds prevents enzymatic... 

Cooler E2 serves to rapidly cool down the liquid product mixture and to recover high-temperature enthalpy. The outlet teirperature of E2 is iii ortant for the overall enthalpy economy since it determines the enthalpy content of the streams exiting at the system boundary. By that it determines the required overall heat input to the main process loop shown in Figure 3. For overall enthalpy economy reasons it should be as low as possible. This tenq>erature is found from optimisation of the hot oil (or high-pressure steam) system that transmits heat from the process furnace to the main process loop. The temperature of the hot oil leaving El cannot be lower than 240 C. This stream picks up the heat from E2, where it is heated to at most 320 C. With these data... 

Steam turbines can become more efficient with hotter primary steam. This in turn requires high-temperature furnaces, and in nuclear power stations, fuel elements that can withstand higher temperatures. Liquid sodium has been used in nuclear reactors as a primary, closed-loop, cooling medium, but the possibility of it corroding the stainless steel used to contain the uranium oxide fuel elements has caused concern. 

Fast Breeder Test Reactor (FBTR) is a 40 MWt/ 13.2 MWe sodium cooled, mixed carbide fuelled, loop type reactor. It has two primary and secondary sodium loops and a common steam water circuit, which supplies high pressure, high temperature superheated steam to turbine generator (TG). Heat is rejected in cooling tower (Fig 1). A 100% capacity dump condenser is provided for reactor operation even when the TG is not in service. The mmn aim of the reactor is to generate experience in the design, construction and operation of sodium cooled fast reactors and to serve as an irradiation facility for the development of fuels and structural material for fast reactors. It achieved first criticality in Oct 85 with Mark I core... 

The CSP plant consists of a solar collector field, a receiver, a heat transfer fluid loop and a heat storage system. The mirrors of the solar field concentrate the direct solar radiation on the solar receiver set at the focal line. The heat transfer fluid (e.g., molten salts) removes the high temperature solar heat from the receiver that is afterwards collected into an insulated heat storage tank to be pumped, on demand, to the heat users (steam generators, endothermic reactors, etc.), where its sensible heat is released. Finally, the heat carrier fluid is stored in a lower temperature tank ready to restart the solar heat collection loop. The idea to match the CSP plant with natural gas steam-reforming Pd-based MR derives from the thermal level reached by molten salt stream (550°C), which meets the thermal requirements of MR (preferred operating at around 500°C). 

The core outlet temperature is set to 900°C, which is below what has been, or will be demonstrated, by the fuels in AVR (Arbeitsgemeinschaft Versuchs Reaktor), HTR-10, HTTR (High Temperature Test Reactor), etc. No safety hazard of water or steam ingress into the primary system exists, since all water and steam circulation is remotely located in the third loop. The nitrogen heater is essentially pressure balanced with a slightly higher secondary pressure to ensure that no fission products enter the secondary system in case of leaking tubes. 

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