Equipment, costs design

It should be emphasized that capital cost estimates using installation factors are at best crude and at worst highly misleading. When preparing such an estimate, the designer spends most of the time on the equipment costs, which represent typically 20 to 40 percent of the total installed cost. The bulk costs (civil engineering, labor, etc.) are factored costs which lack definition. At best, this type of estimate can be expected to be accurate to 30 percent. 

Design UF equipment has considerable variety of design, but the trend is toward more compact, energy efficient, and lower-cost designs. Much of the robustness characteristic of older designs is now available in less costly versions. 

The Calandria Evaporator is applied less often today than it was years ago. For most applications, however, the lower equipment costs for other designs has prompted the replacement of ealandria evaporators with rising-film, LTV falling-... 

The process designer must be aware of costs as reflected in the (1) selection of a basic process route (2) the equipment to be used in the process and (3) the details incorporated into the equipment. The designer must not arbitrarily select equipment, specify details or set pressure levels for design wdthout recognizing the relative effect on the specific cost of an item as well as associated equipment such as relieving devices, instruments, etc. 

Figure 5-51. Flat blade pitched paddle. A simple, low cost design that handles a wide variety of jobs. Operating at low speeds, It gives maximum pumping capacity with a minimum of turbulence. Courtesy of Lightnin (formerly Mixing Equipment Co.), a unit of General Signal.

Like many of the topics discussed in this book, photochemical reactions are most likely to be used in niche applications for commercial and environmental reasons. Unless there is a major breakthrough in reactor and lamp design, widespread use of this technology is unlikely. Perhaps the best hope of producing high-intensity monochromatic sources of radiation rests with lasers, but currently equipment costs are too high to justify their use for commercial chemical production. 

The objective function, Eqn. 7.4-31, will be minimized subject to the horizon constraints of Eqn. (7.4-54) and other conventional constraints, imposed by limits on equipment sizes, etc. Example 7.4-6 illustrates the use of the above model for the minimization of equipment costs in the design of a batch plant. 

For accidents affecting process plant buildings, the potential for serious or fatal injury to building occupants is the foremost concern. Additionally, in cases where buildings house critical controls or equipment, proper design and siting may also help reduce indirect safety impacts (e.g., due to loss of process control), as well as business interruption costs and property loss from such events. 

Capital cost estimates for chemical process plants are often based on an estimate of the purchase cost of the major equipment items required for the process, the other costs being estimated as factors of the equipment cost. The accuracy of this type of estimate will depend on what stage the design has reached at the time the estimate is made, and on the reliability of the data available on equipment costs. In the later stages of the project design, when detailed equipment specifications are available and firm quotations have been obtained, an accurate estimation of the capital cost of the project can be made. 

If the loss can be measured in money, the cash value of the risk can be compared with the cost of safety equipment or design changes to reduce the risk. In this way, decisions on safety can be made in the same way as other design decisions to give the best return of the money invested. 

Equipment cost data used in the early stages of a design will by necessity normally be based on capacity, materials of construction, operating pressure and operating temperature. However, in reality, the equipment cost will depend also on a number of factors that are difficult to quantify15 ... 

Most field equipment used at remediation sites has a lifetime substantially longer than the length of the project where it is used. When the total cost of new equipment is included in the project, the unit treatment cost increases substantially as the time of treatment decreases. Two solutions to this dilemma are common either lease the equipment or use the equipment on several different projects. Both of these options require the equipment to be of some treatment volume rate such that it can be readily applied to another treatment train, and also that it can be portable. If the designer cannot locate lease equipment, or if there is only one project on which to use the equipment, cost calculations should include a salvage value for the equipment. 

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