Elevation of equipment

If the NPSH is not adequate, a change in the elevation of equipment may be necessary. To meet this requirement the receivers that collect condensate are placed about 15 ft above the ground. The pump is then placed directly below at ground level. 

Whenever a change in piping direction occurs, the elevation of the pipe mn should also change. If the main piperack is at an elevation of 4 m, then the lateral piping can either go up to 5 m or drop down to 3 m. The piperack can also provide the support for air coolers and other equipment such as elevated dmms. 

In selec ting the machines of choice, the use of specific speed and diameter best describe the flow. Figure 10-67 shows the characteristics of the three types of compressors. Other considerations in chemical plant service such as problems with gases which may be corrosive or have abrasive solids in suspension must be dealt with. Gases at elevated temperatures may create a potential explosion hazard, while air at the same temperatures may be handled qmte normally minute amounts of lubricating oil or water may contaminate the process gas and so may not be permissible, and for continuous-process use, a high degree of equipment rehability is required, since frequent shutdowns for inspec tion or maintenance cannot be tolerated. 

Air recirculation. Prevailing winds and the locations and elevations of buildings, equipment, fired heaters, etc., require consideration. All air-cooled heat exchangers in a bank are of one type, i.e., all forced-draft or all induced-draft. Banks of air-cooled exchangers must be placed far enough apart to minimize air recirculation. 

Machinery (except electrical) Manufacture of equipment for construction, elevators, moving stairways, conveyors, industrial trucks, trailers, stackers, machine tools, etc. Slag, sand, cores, metal scrap, wood, plastics, resins, rubber, cloth, paints, solvents, petroleum products... 

Flare elevation and spacing must be such that permissible radiant heat densities for persoimel at grade are not exceeded under conditions of maximum heat release. The appropriate calculation procedures and personnel exposure criteria are described later. In some special cases, flare elevation and spacing may be governed by radiant heat exposure of certain vulnerable items of equipment, rather than personnel. 

There are many different types of equipment that are not ditectly connected to the process. One example is elevators, which can influence the ventilation system both when moving and when standing. In addition to the need for ventilation of the elevator, elevator shaft, and machine room, the moving elevator can induce airflows that change the air distribution and airflows in different parts of the building. 

Location The postulated release would occur at an elevation of about 6 m above ground level (a.g.l.) and in a horizontal direction. The flashing liquid jet is likely to impact on surrounding equipment. 

Most equipment failures occur under abnonnal conditions, especially elevated pressures and temperatures. The design of equipment presents internal and external constraints. External limits may arise from physical laws, while internal limits may depend on tlie process and materials. In any case, if these limits are exceeded, tlie chance of an accident is greatly increased. 

Set plant elevations floor elevations of buildings and bottom of steel footings for equipment and large storage tanks. 

When laying out the diagram, it is only necessary to show the relative elevation of the process connections to the equipment where these affect the process operation for example, the net positive suction head (NPSH) of pumps, barometric legs, syphons and the operation of thermosyphon reboilers. 

Prepare a process flow diagram, showing the major items of equipment in the correct elevation, with an indication of their internal construction. Show all major pipe lines and give a schematic outline of the probable instrumentation of the reactor and its subsidiaries. 

Draw a process flow diagram for the plant. This should show all items of equipment approximately to scale and at the correct elevation. The catalyst regeneration, equipment should be shown. 

If there is no special reason for elevating equipment, it should be placed on the ground level. The superstructure to support an elevated piece of equipment is expensive. It can also be a hazard should there be an earthquake, fire, or explosion. Then it might collapse and destroy the equipment it is supporting as well as that... 

Some pieces of equipment will be elevated to simplify the plant operations. An example of this is the gravity feed of reactors from elevated tanks. This eliminates the need for some materials-handling equipment. 

There are many other different types of solids-handling devices, ranging from dumpsters to screw and belt conveyors and bucket elevators. The range and variety of equipment make this subject too large to be adequately covered by this book. The reader is referred to the voluminous literature on the subject. For sizing equipment the most helpful source is often the manufacturers manuals. 

Different types of equipment are available for the investigation of deflagration properties of substances under physical confinement or under elevated pressures. 

Monitors range in size from 250-4,000 gpm (950-15,140 Ipm), with 500 and 1,000 gpm (1,900-3,800 Ipm) the most common sizes. In process areas that are not protected by water spray, monitors should be located so that each major piece of equipment can be covered by two monitors. Elevated monitors have application where it is necessary to deliver large volumes of water to areas that cannot be reached by ground level monitors or would be unsafe for manual firefighting. Elevated monitors can be fixed for remote use, self-oscillating or remote control from a safe location. 

Location and elevation of process equipment with gas or flashing liquids. 

When supporting low-fire-potential equipment Support structure should be fireproofed from its base up to the platform or horizontal bracing plane nearest to an elevation of 40 ft (12 m), but should not terminate below 30 ft (9 m) (see Figure 8-8). 

Operating Pressures. Pressurc/hcad available at equipment inlet and allowable pressure drop within the unit should also be specified. It governs elevation of the treating unit and pimping requirements, if any. 

---