Water drain line

The area below the stack and windbreaker is paved with concrete, surrounded by a 200 mm curb, and graded to a central drain point from which a drain line is routed to a manhole in a vented section of the oily water sewer. The water inlet should be sealed and the manhole should be located at least 15 m from the windbreaker. 

In one incident, a man was draining water, through a 2-in.-diameter line, from a small distillation column rundown tank containing benzene. He left the water running for a few minutes to attend to other jobs. Either there was less water than usual or he was away longer than expected. He returned to find benzene running out of the drain line. Before he could close it, the benzene was ignited by the furnace which heated the distillation column. The operator was badly burned and died from his injuries. 

If water has to be drained regularly from liquefied flammable gases or other flashing liquids, and if a spring-loaded valve cannot be used, then a remotely operated emergency isolation valve (see Section 7.2.1) should be installed in the drain line. 

Some vertical drain lines in a building were no longer needed, so they were disconnected and capped but left connected to the horizontal main drain below. The caps were fixed with tape but were not made watertight as there was no way. it seemed, that water could get into them. Fifteen years later a choke developed in the main drain, water backed up into the disused legs and dripped into an electrical switch box. All power was lost, and some of the switch gear was damaged beyond repair [23]. 

The drain (blowdown) line on a boiler appeared to be choked. It could not be cleared by rodding (the choke was probably due to scale settling in the base of the boiler), so the maintenance foreman pushed a water hose through the drain valve and turned on the water. The choke cleared immediately, and the head of water left in the boiler pushed the hose out of the drain line and showered the foreman with hot water. Although the boiler had been shut down for 15 hours, the water was still at 80°-90°C and scalded the foreman. 

Clearing the choke should not have been attempted until the temperature of the water was below 60°C, the foreman should have worn protective clothing, and if possible a second valve should have been fitted to the end of the drain line as described in (a) above. The accumulation of scale suggests that the water treatment was not adequate [3]. 

After the reaction is completed the products can be poured into water and ice and the aqueous hydrofluoric acid disposed of down the drain. Care must again be exercised as the mixing of hydrogen fluoride and water generates considerable heat. No hazards or disposal difficulties are incurred with hydrofluoric acid in the usual drain lines as these are made of iron pipe and the hydrogen fluoride is soon absorbed as firm complexes with the iron. It is not detectable at any great distance from the source. For some reactions this simple form of disposal is not satisfactory, for example, in the preparation of an acyl halide or other product which reacts with water. Here distillation of the hydrogen fluoride... 

Figure 8.2 shows a common type of reboiler failure. The steam trap on the condensate drain line has stuck open. A steam trap is a device intended to open when its float is lifted by water. The steam trap remains open until all the water drains out of the trap. Then, when there is no more water to keep the trap open, it shuts. But, if the float sticks open, steam can blow through the steam trap. This is called a blown condensate seal. The average vapor velocity through the tubes... 

The total condensation of a vapor to a liquid is best illustrated by the condensation of steam to water. Figure 13.1 is a rather accurate reproduction of the radiator that heated my apartment in Brooklyn. Steam flowed from the boiler in the basement. The steam condensed inside the radiator, and flowed back into the boiler, through the condensate drain line. This is a form of thermosyphon circulation. The driving force for the circulation is the differential density between the water in the condensate drain line and the steam supply line to the radiator (see Chap. 5, discussion of thermosyphon reboilers). 

The bigger the radiator, the more heat is provided to a room. The bigger the radiator, the faster the steam condenses to water inside the radiator. A larger radiator has more heat-transfer surface area exposed to the condensing steam. Unfortunately, the radiator shown in Fig. 13.1 is suffering from a common malfunction. Water-hardness deposits have partly plugged the condensate drain line. Calcium Carbonate is a typical water-hardness deposit. 

For a surface condenser to work properly, noncondensable vapors must be sucked out of llie shell side. This is done with a two-stage jet system, as shown in Fig. 18.3. When I was first commissioned the jets, they were unable to pull a good vacuum. Moreover, water periodically blew out of the atmospheric vent. I found, after considerable investigation, that the condensate drain line from the final condenser was plugged. 

The mixture of organohydroxysilanes (silanols), distilled to a 45-50% concentration, is vacuum-pressurised from tank 13 into weight batch box 17 and sent to condense in condenser 18, which has an agitator and a water vapour jacket. The condensation of the silanol mixture is carried out in vacuum under 285-340 GPa at 90-95 °C, until toluene no longer enters the run-down box on the drain line from cooler 19. The toluene enters collector 20 and is sent to regeneration. 

A Water Drain Line Is Altered and a Reactor Explodes... 

The operations team in this area of the plant was convinced that if changes were to be made in any equipment, reactants, intermediates, catalyst, or any operating conditions of the process were modified, the system would be first reviewed by a committee. In the operations teams mind, this was just a waste water line. As is apparent in Figure 2—18, the danger of just blocking the water drain lines at any time the system is in operation would cause physical explosion. 

Water, gas, electrical and drain lines are contained in chases which run vertically between floors on either side of the hall. Outside each laboratory there is a locked access panel in the chase, the key to which is kept in the laboratory. In an emergency any utilities to a single laboratory may be shut off from this chase. Of course, the building is equipped with the usual array of smoke and heat detectors and fire alarms. 

The chemist simply leads steam from a pressure cooker into the styrofoam party cooler via automotive vacuum tubing. The lid is on the cooler, with a small hole in the lid of the cooler for the top of the bottle to stick out of, or for the hydrogen line to get in through. It is best to poke a small hole in the side of the cooler near the bottom, and stick some plastic tubing into it. This acts as a drain line to carry away condensed water. 

Must ensure that the autoclave is located in a bounded area to control water leaks, has good access for maimenance, has an air-break in the drain line, has sample ports for sicam and water lesiing. is located in an area that allows for heat dissipation. Must demonstrate that all operating systems are working, that all safety systems are working, that the autoclave has been tested for leaks and other malfunctions, that there is cycle to cycle continuity of performance. Must include calibration of all control equipment... 

The flap valve should be operable, be chain, at the curb or dike wall and should be closed at all times except to drain surface water from the enclosure sifter rain storms. Instead of the flap valve, a gate valve may be used for containing contents of the enclosure. The gate valve should be installed in the sewer line, outside of the enclosure and be provided with an extension stem for operation at grade level. 

Opening of any valve to a vacuum column is likely to suck in the contents of that line, and possibly materials from other equipment connected to it. These must be thoroughly dried prior to opening the valve. A pressure surge incident resulting from sucking water from a drain line into a vacuum column has been described (4). 

Blown condensate seal. When this occurs, uncondensed vapor blows and channels right through the reboiler and out the condensate drain line. Heat transfer slumps and water hammer may follow. Experience shows that as much as half the reboiler duty is lost by a small amount of vapor blowing (239). Throttling the reboiler outlet reestablishes the seal. Installation of a condensate seal drum can cure this problem. Additional discussion is in Sec. 17.1.2. 

The row of laboratories should be backed up to a physical/mechanical support chase that supplies water, electricity, vacuum, gas, air, and drain lines. The support chase should be large enough to accommodate maintenance personnel and equipment, but access should be restricted for other facility personnel. Some designs incorporate an overhead mechanical room or eliminate the limited-access support chase. All air supplies and ductwork should be overhead and directly accessible from a maintenance penthouse that holds Alter banks and scrubbers. 

For removing water floating on a chlorinated hydrocarbon bottom layer, two or three drain valves at easily accessible positions should be provided. The valves should be fitted close to the tank sides to avoid the danger of the drain lines freezing up. Product tanks should be fitted with pressure-vacuum valves and with self-closing dip and sample hatches. 

To cool the beryllium section, one end of the extended water pipe is connected to the supply-water line the other end is connected to the drain line. In an attempt to forecast future demands of this facility, a coolant return loop is provided. The 8-in. horizontal graphite hole, HG-2, has. been chosen to serve as the coolant.return loop. It is ideal because it runs parallel to the through hole, HT-1, and also passes completely through the reactor. 

---