Ruptured tube flow

Provisions should be made to direct flammable or combustible liquid spills away from fired heaters. Spills from other equipment that flow into or under fired heaters can and have been ignited by the hot surfaces or flames of fired heaters. Conversely, in the past, spills from ruptured tubes in process heaters have allowed burning liquid to flow around and damage other equipment. Both process heaters and nearby equipment should be protected from each other due to possible spills of flammable or combustible liquids using one of the following methods ... 

Answer Corrosion of tubes would leetd to tube leaks which permit water to enter the graphite block with a resultant loss in multiplication factor and with further corrosion of tubes due to an alumlnum-graihlte-water reaction. Slug Jacket corrosion leads to ruptures which permit the highly radioactive fission products In the metal to enter the water stream. The chemical action between the metal and water would cause the slug to expand with harmful effects on tube flow rates and difficulty in removal of the swollen piece. 

API RP 521, Section 3.18.5, indicates that, where the low-pressure side is in the vapor phase, full credit can be taken for the vapor handling capacity of the outlet and inlet lines, provided that the inlet lines do not contain check valves or other equipment that could prevent back flow. The same approach would apply in cases in which the low-pressure side is liquid full, provided that the released material also remains in the liquid state. However, when the low-pressure side contains liquid and vapor is released or generated through a rupture tube, the effective relieving capacity with which the piping system can be credited should be based solely on an equivalent vapor flow. 

The flow through the ruptured tube is calculated based on normal pressure of the high-pressure side and relieving pressure of the low-pressure side. 

Noncompressible flow. The normal Darcy equation is used in calculating the flow through a ruptured tube. The pressure drop calculated using the Darcy equation is... 

Compressible flow. For compressible fluids, the flow through a ruptured tube is calculated based on the Lapple equation [9,10]. 

For a fired reboiler, a pump-around system is used with an FRC to maintain constant flow. There will be a low flow alarm plus fuel shutoff. There will also be a high flow alarm plus fuel shutoff, since a tube rupture would reflect itself in a high flow. 

At 40 MW operation, the core damage frequency is 3.7E-04/y. The proportion of accident classes is LOCA, 50% beam tube rupture, 27% ATWS, 17% LOOP, 4% and other transients, 2 7. Three minutes of forced flow are not required and large LOCAs with break size smaller than 2.8 inches can be mitigated. 

Tube Rupture. It is common for a heat exhanger to have a high-pressure fluid in the tubes and a lower-pressure rated shell. If there is a break in one of the tubes, the higher pressure fluid will leak to the shell, resulting in overpressure. It is conservative to assume a tube is completely split with choked flow from both sides of the break. 

In the case of the capillary blood, it is extremely important that the specimen not be allowed to stand for extensive periods of time before centrifugation. If the blood is to be transferred to the pH meter, then the collecting tube is sealed at both ends during transportation. It is then aspirated into the pH instrument as soon as practicable since one needs a smooth even flow in order to aspirate a specimen into the conventional micro pH meter. After the whole blood has been sampled for various purposes, it is important that the remaining blood be centrifuged promptly. If not, it will clot. Subse-quentially, centrifuging with a clot will tend to hemolyze the blood. Erythrocytes will adhere to the wall and as they are pulled down by the clot, they will be ruptured. Those who do not observe these precautions will find that it is rather difficult to obtain unhemolyzed blood. 

For small-tube-rupture flows that simulated the flow from the single-ended rupture of up to 16 steam generator tubes in a PWR system initiated at the start of vessel refill, the core thermal response was strongly dependent on the magnitude... 

Isolation or emergency shutdown (ESD) valves should be installed to stop fuel flow and the process feed flow into the heater in the event of heater tube rupture. These valves can be automatically actuated by controls or safety interlocks or can be manually operated remotely. Remote actuation can be from a control room console or in the field field actuation stations should be located at least 50 ft (15 m) from the heater. It is also common to provide a manual block valve, located at least 50 ft (15 m) from the heater, on each of the fuel and process feed lines. These should be accessible to operators in the event of an incident involving the heater. 

Edition of January 1995. The evaluation of relevant mass-flows is according to safety valves. The use of rupture-discs requires some experience from the design engineer concerning positioning and reaction forces. The exhaust of all safety valves and rupture discs should be connected to a common blow-off tube, at a level above the building. 

Fig. 7.2. Diagram of the PDS-1000/He, a stationary particle bombardment machine that is connected to a helium gas container. Controlled by adjustable valves, the gas stream (He) terminates in an acceleration tube, which is mounted on the top of a target chamber. This chamber is closed by a door and set under vacuum shortly before bombardment. When gas flows into the acceleration tube, the rupture disc bursts releasing the shock wave into the lower part of the tube. The gas pressure then accelerates the macrocarrier sheet containing the microprojectiles on its lower surface. The net-like stopping screen holds the macrocarrier sheet back and serves to block the shock wave, while the microprojectiles slip through the pores of the grid and continue on towards their final target.

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