Centrifugal discharge pressure filter

Figure lliK) Centrifugal discharge pressure filter (Courier of Schenk Fiheibau GmHl, Waldstetten, Germany)... 

Fuel systems can cause many problems, and fuel nozzles are especially susceptible to trouble. A gaseous fuel system consists of fuel filters, regulators, and gauges. Fuel is injected at a pressure of about 60 psi (4 Bar) above the compressor discharge pressure for which a gas compression system is needed. Knockout drums or centrifuges are recommended, and should be implemented to ensure no liquid carry-overs in the gaseous system. 

Here is a problem that came up on a sulfur recovery facility in Punto Fijo, Venezuela. The combustion air blower, shown in Fig. 28.8, was a fixed-speed, motor-driven centrifugal machine. The air intake filters were severely fouled. They had a pressure drop of about 8 in H/). The atmospheric vent valve, used to control the discharge pressure at a constant 12 psig, was 50 percent open. The unit engineer had been asked to calculate the incentive in electrical power savings that would result from cleaning the filters. 

Cake filters separate relatively large amounts of solids by forming a cake on the surface of the filtration medium. Cake filters may be operated by applying pressure on the upstream section of the filter medium or vacuum on the downstream section of the filter medium. The operation of the filters may be continuous or discontinuous. However, most pressure filters are discontinuous since the operation of the filter under positive pressure needs to be stopped to facilitate the removal and discharge of solids. Examples of cake filters include filter press, vacuum filter, and centrifugal separator. 

The air supplied to each air cooler tray is first filtered to remove dust and then pressurized using a spark-proof centrifugal blower. After the cool air enters the trays, it flows upward through the meal at a nominal velocity of 14 to 21 m/minute, partially fluidizing the meal. The meal continues to evaporatively cool and convec-tively cools. The cool, damp air exits the top of the meal layer and then exits the sidewall of the DC to a cyclone collector to remove dust prior to discharge to atmosphere. 

The volumes of reactor and crystallization vessels vary widely, between 1000 and 10,000 L, or in rare cases, 16,000 L. Reactors with standard sizes of 4000 and 6300 L are used most commonly. Multipurpose plants also differ with regard to the degree of sophistication. Simple plants are equipped with jacketed reactors that operate at limited ranges of temperature (-10 to -f 120°C) and pressure (20 mbar to 5 bar). Also, the filters and centrifuges are discharged manually, and the dry section is not contained. Process control is manual. 

Cleaning the filters would have raised the suction pressure to the blower. This would have reduced the blower s compression ratio. But because the blower is a fixed-speed centrifugal compressor, the amount of air compressed N would have increased. The atmospheric vent discharge valve would have been forced open. The greater volume of air compressed would have caused the compressor to work harder, even though the compression ratio was lower. In conclusion, clean-... 

---