Pressure relief valve heat exchangers

Pressure relief valves are provided to cater to two main conditions of the process -normal conditions and emergency conditions. Normal conditions relate to the designed operation of the process which emergency conditions can be caused by either (1) external fire conditions, (2) failure of reflux or cooling, (3) Failure of the power supply, (4) failure of steam supply, (5) heat exchanger failure (6) introduction of incompatible materials, (7) thermal expansion with outlets closed. 

The high-pressure pumps are normally supplied with a pressure relief valve and associated product piping to protect the scraped-surface heat exchanger equipment downstream and the pump itself, should a blockage of the production line occur. 

Figure 7 Schematic diagram of semipreperative-scale SFC chromatograph 1 carbon dioxide supply 1 a regulator 2 prechiller/heat exchanger 3 SD-1 Varian pump with (7) 200-mLpump head with special check valves 4 modifier reservoir 5 SD-1 modifier pump with (6) 200-mL standard pump heads 8 check valve 9 inlet pressure transducer 10 injection valve 11 check valve to prevent blow-back 12 mixer 13 fluid temperature preconditioner 14 column 15 column oven 16 uv detector 17 outlet pressure transducer 18 back-pressure regulator 1 9 evaporator 20 restrictor 21 trim heater 22 selection valve 23 peak detector 24 bank of collection vessels (or cassette) 25 individual collection tubes/bottles 26 pressure relief valves 27 waste container, waste vent. The manual cassette can be replaced with an automated cassette fed by a robot holding 128, 25 x 150-mm or 338, 16 x 150-mm test tubes, or with 7 large bottles.

Figure 1.19 shows a shell and tube heat exchanger. Hydrocarbon vapors enter the exchanger on the shell side where they are condensed by cooling water which runs through two passes of tubes. The pressure relief valve and the drain and vent valves on the shell side are shown. 

Steam heating of blocked in exchangers or steam tracing of pipe or other equipment completely full of liquid can result in dangerously high pressures if a pressure relief valve is not provided. Liquids expand when heated. If a full vessel is blocked in and heated,... 

Pressure relief valves on cooling water lines can be avoided by locking the cooling water inlet and outlet valves for the heat exchanger... 

Separation of the extract from the supercritical solvent consists of the precipitation vessel, 2 1, maximum pressure 1(X) MPa, and a pressure relief valve. In some cases a heat exchanger is employed between pressure reduction and inlet to the precipitator. 

Shell and tube heat exchangers seldom have pressure relief valves for fire exposure because vapors will quickly flow to the next pressure vessel, from which they can be discharged. The two-thirds rule from API RP 521 states ... 

Eluor Daniel has the ability to perform a heat exchanger tube rupture transient analysis consistent with the method referred to in RP-521 ("Model to Predict Transient Consequences of a Heat Exchanger Tube Rupture," by Sumaria et ah). This methodology accounts for effects such as the inertia of the low-pressure liquid, the compressibility of the liquid, the expansion of the exchanger shell or tube chaimels, and the relief valve dynamics. Dynamic simulation can be used to meet the following objectives ... 

Many operators use a simpler system, using V for pressure vessel, T" for tank, P for pump, C for compressor, and E for heat exchanger, in which case the relief valve would be designated ... 

In the event of a HX tube rupture, a blow down of secondary CO2 (initially at 20 MPa) into the lead occurs. Molten lead and CO2 do not react chemically. Protection against over pressurization of the primary coolant vessel must be provided and activity that is entrained from the lead coolant into the CO2 must be contained. Thus, a pressure relief system is provided for the primary coolant system. The S-CO2 secondary circuit incorporates valves to isolate the failed heat exchanger and limit the mass of CO2 that can enter the primary coolant system. The CO2 released from the primary coolant system is contained inside of a volume. 

The system consists of two blowdown trains, one for each steam generator. The blowdown water is extracted just above the tube sheet of a steam generator. Flow control valves adjust the blowdown flow rate from each steam generator and depressurise it. The blowdown flow is cooled by means of a regenerative heat exchanger, which uses the heat to warm the condensate. It then enters an ion-exchange purification unit, which removes impurities. Downstream of the purification unit, both trains combine into a common header, which contains a relief valve for providing overpressure protection for the low-pressure portion of the system. 

For the controlled removal of the liquid phase of a liquefied gas, a manual flow-control valve is used. Special liquid flow regulators are also available. Removal of the liquid must be done at the vapor pressure of the material. Care must be taken to prevent blockage of the gas line downstream from a user s heat exchanger, which would cause excessive pressure buildup in the heat exchanger and the cylinder. Pressure relief devices should be installed in all transfer lines to relieve any sudden and dangerous hydrostatic or vapor pressure buildups. 

Man Cognitive function (observation) Observation missed Second operator did not observe closed status of isolation valve and closed block valve, isolating the ammonia pressure control valve from the heat exchange. Afterwards, he started to steam the process line to clean the pipeline. The closed isolation and block valves prevented the increasing ammonia pressure from safely venting through either the ammonia pressure control valve or the rupture disk and relief valve. 

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