Vessels costs

Bare vessel cost (Figure 6.5a) 21,000 material factor 1.0, pressure factor 1.1... 

A reactor vessel cost 365,000 in June 1998, estimate the cost in mid-2004. 

A typical plate is shown in Figure 11.22. The plate sections are supported on a ring welded round the vessel wall, and on beams. The beams and ring are about 50 mm wide, with the beams set at around 0.6 m spacing. The beams are usually angle or channel sections, constructed from folded sheet. Special fasteners are used so the sections can be assembled from one side only. One section is designed to be removable to act as a manway. This reduces the number of manways needed on the vessel, which reduces the vessel cost. 

As expected, D decreases and L increases as (-AP) increases. For a given amount of catalyst, a reduced pressure drop (and operating power cost) can be obtained by reducing the bed depth at the expense of increasing the bed diameter (and vessel cost). 

The first example was formulated by Stoecker to illustrate the steepest descent (gradient) direct search method. It is proposed to attach a vapor recondensation refrigeration system to lower the temperature, and consequently vapor pressure, of liquid ammonia stored in a steel pressure vessel, for this would permit thinner vessel walls. The tank cost saving must be traded off against the refrigeration and thermal insulation cost to find the temperature and insulation thickness minimizing the total annual cost. Stoecker showed the total cost to be the sum of insulation cost i = 400jc° 9 (x is the insulation thickness, in.), the vessel cost v = 1000 + 22(p — 14.7)1-2 (p is the absolute pressure, psia), and the recondensation cost r = 144(80 — t)/x (t is the temperature, °F). The pressure is related to the temperature by... 

Process pressure vessel cost. Process pressure vessels are always designed in accordance with the current ASME code. These major equipment items are always cylindrical metal shells capped with two elliptical heads, one on each end. Installation can be either vertical or horizontal. Vertical is generally a fractionation-type column with internal trays or packing, although the smaller-height vertical vessels (less than 15 ft) are mostly two-phase scrubber separators. The horizontal vessel is generally a two- or three-phase separation vessel. 

Figure 8.7 provides fractionation column internal trays that are to be added to the overall pressure vessel cost. A packed-column internal (random packing) cost is also given as cost per cubic foot of column-packed volume. 

We assume that the reactor is constructed from fairly exotic material and has heat transfer equipment (jacket or coil) and an agitator. So the capital cost is estimated at 10 times the basic vessel cost. The total capital costs of the reactors in the three different flowsheets are 7,429,000, 4,043,000, and 3,657,000 for the 1-CSTR, 2-CSTR, and 3-CSTR processes, respectively. You can see that the reduction in cost between the 2-CSTR and the 3-CSTR processes is quite small. The cost of a 4-CSTR process could be somewhat higher because of having more vessels, even if each is somewhat smaller. 

Numerous articles have been published which give methods for obtaining vessel costs based on estimates of costs for the individual components, such as for materials, labor, nozzles, manholes, and overhead related to fabrication, to arrive at an estimated cost (f.o.b) at the fabricator s shop. Final installed cost can be obtained by applying factors to account for freight, labor, materials, engineering, and overhead related to getting the unit to the plant and installing... 

Lang factors to convert from the base cost of the delivered vessel (costed as if it were of carbon-steel material of construction so that weight becomes the primary measure of installation cost) to the cost of the vessel installed with all necessary auxiliaries except special internals such as trays or agitators are 3.0 for vessels installed in a horizontal position and 4.0 for vessels installed in a vertical position. 

For each head (either top or bottom), add equivalent cost of 5 ft additional length per vessel. Cost data are given in Table 3. 

When an estimator costs pressure vessels such as reactors and distillation columns, care must be taken to ensure that the wall thickness is adequate. The default method in IPE calculates the wall thickness required based on the ASME Boiler and Pressure Vessel Code Section VIII Division 1 method for the case where the wall thickness is governed by containment of internal pressure (see Chapter 13 for details of this method). If other loads govern the design, then the IPE software can significantly underestimate the vessel cost. This is particularly important for vessels that operate at pressures below 5 bara, where the required wall thickness is likely to be influenced by dead weight loads and bending moments from the vessel supports, and for tall vessels such as distillation columns and large packed-bed reactors, where wind loads may... 

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