Answer:
11.8.4 Distillation Columns
Distillation columns present a hazard in that they contain large inventories of flammable boiling liquid, usually under pressure. There are a number of situations which may lead to loss of containment of this liquid.
The conditions of operation of the equipment associated with the distillation column, particularly the reboiler and bottoms pump, are severe, so that failure is more probable.
The reduction of hazard in distillation columns by the limitation of inventory has been discussed above. A distillation column has a large input of heat at the reboiler and a large output at the condenser. If cooling at the condenser is lost, the column may suffer overpressure. It is necessary to protect against this by higher pressure design, relief valves, or HIPS. On the other hand, loss of steam at the reboiler can cause underpressure in the column. On columns operating at or near atmospheric pressure, full vacuum design, vacuum breakers, or inert gas injection is needed for protection. Deposition of flammable materials on packing surfaces has led to many fires on opening of distillation column for maintenance.
Another hazard is overpressure due to heat radiation from fire. Again pressure relief devices are required to provide protection.
The protection of distillation columns is one of the topics treated in detail in codes for pressure relief such as APIRP 521. Likewise, it is one of the principal applications of trip systems.
Another quite different hazard in a distillation column is the ingress of water. The rapid expansion of the water as it flashes to steam can create very damaging overpressures.
Living things are a resource for humans. They are a renewable resource because they reproduce. A forrest that has been cut down can regrow and animals can give birth to babies.
The correct answer is due to rapid conversion of nitrates into nirites in extracellular fluids.
Due to the fact that it is quickly transformed to nitrates and nitrites in the extracellular fluid, nitric oxide (NO) functions as a paracrine signal that only impacts nearby cells. Because it relaxes the smooth muscle cells in blood vessel walls, nitric oxide (NO) causes blood vessels to widen. Cell signaling is a type of cellular communication in which a cell produces a signal to cause changes in neighboring cells, changing the behavior of those cells. Paracrine signaling is one type of cell signaling. Responses to allergens, tissue repair, the development of scar tissue, and blood clotting are a few examples of paracrine signaling. The transmission of signals through synapses between nerve cells is known as paracrine signaling.
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