Discharge tank

Fig. 12. Unipol PP process where A is the polymerization reactor B, recycle gas compressor C, recycle gas cooler D, product discharge tank E, impact copolymer reactor F, recycle gas compressor G, recycle gas cooler and H, product discharge tank (134).

If the tank has some headspace, as is usually the case, it is desirable to get a better estimate of the ac tual level, since tanks usually have some gas headspace even when filled with hquid. Two tank configurations are considered the gravity discharge tank (discharge is open to the atmosphere) and the pumped discharge tank. These calculations assume that the process is so rapid that an adiabatic model for the gas in the headspace is the correct choice. This is true when the drainage... 

Table A13.5 Average test results ol eftiuent discharge (tank wash and spray booth mix of a medium-sized paint shop under consideration) before and after treatment...

One component of the TDH is the Hs, the static head. In this example the surface level in the discharge tank is 115.5 ft above the pump centerline. The surface level in the suction tank is 35.5 ft above the pump centerline. The AHs, by observation is 80 ft. See Figure 8-6. 

There is a sudden reduction in the suction between the tank and the piping. There is an eccentric 6-to-4 reducer between the suction pipe and the pump. There is a eoneentrie 3-to-4 inereascr from the pump back into the piping, and a sudden enlargement going into the discharge tank. The formula is ... 

Figure 12-1. The Union Carbide Unipol process for producing HDPE (1) reactor, (2) single-stage centrifugal compressor, (3) heat exchanger, (4) discharge tank.

Figure 12-2. The Union Carbide gas-phase process for producing polypropylene " (1) reactor, (2) centrifugal compressor, (3) heat exchanger, (4) product discharge tank (unreacted gas separated from product), (5) impact reactor, (6) compressor, (7) heat exchanger, (8) discharge tank (copolymer separated from reacted gas).

Toluene is to be pumped between two vessels using a centrifugal pump with a flowrate of 30t h 1. The pipe diameter is 80 mm (internal diameter 77.93 mm). The pipeline is 35 m long, with 4 isolation valves (plug cock), a check valve and 5 bends. The discharge tank is 3 m in elevation above the feed tank. The density of toluene is 778 kgrn 3 and viscosity of 0.251 x 10 3 N-s-rn 2. 

The granular product flows intermittently into product discharge tanks (4) where unreacted gas is separated from the product and returned to the reactor. Hydrocarbons remaining with the product are removed by purging with nitrogen. The granular product is subsequently pelletized in a low-energy system (5) with the appropriate additives for each application. 

To make impact copolymers, the polypropylene resin formed in the first reactor (1) is transferred into the second reactor (5). Gaseous propylene and ethylene, with no additional catalyst, are fed into the second reactor to produce the polymeric rubber phase within the existing polypropylene particles. The second reactor operates in the same manner as the initial reactor, but at approximately half the pressure, with a centrifugal compressor (6) circulating gas through a heat exchanger (7) and back to the fluid-bed reactor. Polypropylene product is removed by product discharge tanks (8) and unreacted gas is returned to the reactor. 

Further studies seemed to eonfirm this presumption. To that end, a once-through open-loop 7/8-inch pipe viscometer, whieh is deseribed elsewhere (250), was used. The steady-state pressure drop readings could be made at two loeations in the pipe Leg 1 the nearest to tiie pump and Leg 2 the nearest to the discharge tank, i.e., fijrther away in the flow sequence. 

The outlet pipe from the reactor to the discharge tank has a diameter of d = 0.2 m. 

Figure 4.9 presents the nitrator with the emergency discharge tank. 

According to [18] a conservative ( pessimistic ) assessment shows that 18 s are available to discharge the reactor contents safely into the emergency discharge tank. Is this enough if a coefficient of discharge of p = 0.82 (cylindrical connection) is used ... 

The temperature control loop is equipped with temperature alarm TAl. Its signal is to prompt the operator to open the bypass of the temperature control, to stop the hexamine supply and to discharge the reactor contents by pushing an emergency button, which in addition activates the stirrer motor M2 of the emergency discharge tank. 

The temperature would reach 25 °C and remain there despite full cooling power, if the reactor contents were not discharged to the emergency discharge tank after about 70 s. If the hexamine feed is stopped by TSH2, the discharge would take place after 419 s. After that the reaction comes to a standstill and the reactor temperature drops to —3.5 °C. 

A standard reactor used in the process industry for synthesis reactions is shown in Fig. 9.59. The corresponding fault tree model is presented in Fig. 9.60. Reactants A and B are introduced in controlled quantities into the reactor. A catalyst is continuously supplied and the temperature as well as the pressure increases are measured. The protective trip system consists of the safety valve SVl and the relief system made up of pressure switch PSHHl, relay 1, and pneumatic valve AVI. The safe place for relief is considered to be a discharge tank just as that of Fig. 4.11, which is modelled as in Fig. 9.56. 

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