Heat exchanger cost estimation

Example 2.1 A new heat exchanger is to be installed as part of a large project. Preliminary sizing of the heat exchanger has estimated its heat transfer area to be 500 m2. Its material of construction is low-grade stainless steel, and its pressure rating is 5 bar. Estimate the contribution of the heat exchanger to the total cost of the project (CE Index of Equipment = 441.9). 

A chart to estimate the costs of ejectors for thermocompression has been developed.Approximate costs of compressors for mechanical vapor recompression also can be found. In addition, these publications contain details of cost estimation for heat exchangers. For more detailed estimation of cost of shell-and-tube exchangers, see Purohit. " Plate-and-frame and spiral-plate heat exchanger costs can be estimated using Kumana. " ... 

To this point in the discussion, it has been assumed that the cost of the heat exchanger is sinply a function of the heat transfer surface area. From discussions in Chapter 7, it is clear that both the materials of construction and operating pressure are inportant factors in estimating heat-exchanger costs. These effects must be taken into account when estimating the FCI from the conposite tenperature-enthalpy diagram. This problem has been addressed by Hall et al. Fill and is explained in the following section. 

Base equipment includes all equipment within the battery limits whose cost is as significant as the cost of a pump. For example, storage tanks, knockout drums, accumulators, heat exchangers, and pumps are classed as main-plant items (MPl). Early in the development of the process-flow diagram, it is advisable to increase the estimated (MPl) cost by 10 to 20 percent to allow for later additions. When the scope of the process has been well defined, (MPl) costs should be increased by 1 to 10 percent. 

Costs of shell-and-tube heat exchangers can be estimated from Fig. 11-41 and Tables 11-13 and 11-14. These 1960 costs should be updated by use of the Marshall and Swift Index, which appears in each issue of Chemical Engineering. Note that during periods of high and low demand for heat exchangers the prices in the marketplace may vary significantly from those determined by this method. 

Pressure storage tanks should be coirelated using /lb vs. w eight, much the same as other pressure vessels. Materials of construction, of course, would be another variable. Special internals, insulation, and internal heat exchangers should again be separated from the base cost of the tank. The w eight of supports, ladders, and platforms should be estimated and added to the weight of the... 

Corripio, A. B., Chrien, K. S., and Evans, L. B.. Estimate Costs of Heat Exchangers and Storage Tanks Via Correlations, Chemical Engineering. Jan. 25,... 

Purohit, G. R, Estimating Costs of Shell and Tube Heat Exchangers, Chemical Engineering, Aug. 22,... 

In order to illustrate the use of cost indices and scaling factors, let us consider the following example. In 1992, the cost of a 50 m shell-and-tube beat exchanger was 24,000. Estimate the cost of a 100 m shell-and-tube heat exchanger of a similar type and materials of construction in 1996. 

Let us assume that the scaling factor for the heat exchanger is 0.6. Hence, in 1992, the cost of the 100 m shell-and-tube heat exchanger can be estimated from Eq. (I1I.2) to be... 

For example, in the aforementioned heat exchanger example let us consider that water is used as a coolant at the rate of 120.0 gallons per minute (gpm) at a cost of 0.20/1000 gallons. Annual labor and maintenance is estimated to be 31,000/year. Hence,... 

The purchased cost of a shell and tube heat exchanger, carbon shell, stainless steel tubes, heat transfer area 500 m2, was 7600 in January 1998 estimate the cost in January 2006. Use the Process Engineering plant index. 

The cost of specialised equipment, which cannot be found in the literature, can usually be estimated from the cost of the components that make up the equipment. For example, a reactor design is usually unique for a particular process but the design can be broken down into standard components (vessels, heat-exchange surfaces, spargers, agitators) the cost of which can be found in the literature and used to build up an estimate of the reactor cost. 

Pikulik and Diaz (1977) give a method of costing major equipment items from cost data on the basic components shells, heads, nozzles, and internal fittings. Purohit (1983) gives a detailed procedure for estimating the cost of heat exchangers. 

Solution From Equation 2.1 and Table 2.1, the capital cost of a carbon steel heat exchanger can be estimated from ... 

The cost of a carbon steel heat exchanger needs to be adjusted for the material of construction. Because of the low pressure rating, no correction for pressure is required (Table 2.5), but the cost needs to be adjusted for the material of construction. From Table 2.4, /m =2.9, and the total cost of the installed equipment can be estimated from Equation 2.6 and Table 2.7. If the project is a complete new plant, the contribution of the heat exchanger to the total cost can be estimated to be ... 

Had the new heat exchanger been an addition to an existing plant that did not require investment in electrical services, utilities, offsites, buildings, site preparation or working capital, then the cost would be estimated from ... 

In turn, the area of the heat exchanger can be used to estimate the annualized capital cost ... 

It should be noted that a resequence or repipe does not involve zero capital cost, even though no new heat exchanger equipment might be purchased. The pipework modifications for a resequence or repipe might be very expensive. Also, equipment might need to be relocated. Methods for capital cost estimation for retrofit were discussed in Chapter 2. 

Suppose the cost for a fixed-head heat exchanger constructed of 316 stainless steel operating at 300-600 psi is to be estimated. The base case is a carbon steel, floating-head exchanger operating at 100 psi of area A. For such operation (Kuri and Corripio 1984), the base cost is... 

A convenient way to display cost-capacity data is by algorithms. They are readily adaptable for computerized cost estimation programs. Algorithm modifiers in equation format may be used to account for temperature, pressure, material of construction, equipment type, etc. Equation (9-2) is an example of obtaining the cost of a shell-and-tube heat exchanger by using such modifiers. 

Major items of equipment include reactors, heat exchangers, columns, vessels, etc. Ancillary equipment such as process piping and insulation can be estimated after the total cost of the major items is known. 

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