Pipe capital cost

Suppose you want to design a hydrocarbon piping system in a plant between two points with no change in elevation and want to select the optimum pipe diameter that minimizes the combination of pipe capital costs and pump operating costs. Prepare a model that can be used to carry out the optimization. Identify the independent and dependent variables that affect the optimum operating conditions. Assume the fluid properties (/i, p) are known and constant, and the value of the pipe length (L) and mass flowrate (m) are specified. In your analysis use the following process variables pipe diameter (D), fluid velocity (v), pressure drop (A/ ), friction factor (/). 

Economic velocities for turbulent flow (the most common industrially), taking into account piping capital costs (piping, fittings, pumps, etc.) and running costs (pressure drops), are primarily a function of fluid density [A/ fT oc pu2]. Details are given in the literature.4 Order of magnitude economic velocities are ... 

Another way to raise the power/heat ratio is by raising the pressure of the steam system. An increase in pressure from 4.2 to 10.1 MPa (600 to 1500 psi) almost doubles the power associated with a given steam load. (Power/heat ratio increases from 0.12 to 0.20). This, however, comes at appreciable capital cost for alloy materials of constmction in the boiler, piping, and turbines. It also requires... 

There is much to be said in favor of carrying the steam to the points where it is to be used, at a pressure close to that of the boiler. The use of a high-distribution pressure means that the size of the steam mains is minimized. The smaller mains have lower heat losses, so that better-quality steam at the usage points is more readily achieved and the smaller pipes are often much lower in capital cost. 

A simple cell design is required to reduce capital costs. The cost of the raw materials, HF and electricity, are not negligible, but they are minor. The pilot plant cell design shown in Fig. 16 is derived from the callandria cell developed for the Phillips ECF process.14 The cell body and internals are of mild steel pipe selected to be resistant to hydrogen embrittlement. Figure 17 is a horizontal section through the working part of the cell. 

The capital cost of a pipe run increases with diameter, whereas the pumping costs decrease with increasing diameter. The most economic pipe diameter will be the one which gives the lowest annual operating cost. Several authors have published formulae and nomographs for the estimation of the economic pipe diameter, Genereaux (1937), Peters and Timmerhaus (1968) (1991), Nolte (1978) and Capps (1995). Most apply to American practice and costs, but the method used by Peters and Timmerhaus has been modified to take account of UK prices (Anon, 1971). 

Constraints might be applied for the sake of reducing the capital costs (e.g. to avoid long pipe runs). In addition, constraints might be applied to avoid complex heat integration arrangements for the sake of operability and control (e.g. to have heat recovery to a reboiler from a single source of heat, rather than two or three sources of heat). 

In addition to these complexities, there may be other issues that need to be included in the analysis that are not readily included using the graphical approach. These might include forbidden matches (e.g. because a long pipe run may be necessary), compulsory matches (e.g. for operability) and capital cost issues (e.g. the cost of running pipes between operations). 

The objective function is comprised of the sum of the annual operating and maintenance costs of the compressors and the sum of the discounted capital costs of the pipeline segments and compressors. The annualized capital cost for each pipe section is assumed to be proportional to its length and its diameter. Similarly the annual operation and maintenance charges of a compressor is assumed to be proportional to the horsepower which is given by... 

The total cost of a pipeline or piping system includes the capital cost of both the pipe and pumps as well as operating costs, i.e. the cost of the energy required to drive the pumps ... 

The initial evaluation showed that utilizing fiber-reinforced polymer (FRP) for pipelines is a feasible alternative to steel pipelines with regard to performance and cost [35]. From the cost analysis, an FRP pipe is quite attractive, especially in the regional or distributed service. Currently, spoolable piping manufacturers could install a composite pipeline for serving a 100,000 population for a cost of 250,000-500,000/mi. (does not include the cost for right-of-way), which is well below the DOE s capital cost target in 2017 of 800,000/mi. [35]. From this estimate and cost analyses, it is seen that FRP pipe economics is very attractive, especially for the distribution service. 

As noted above, batch and semi-batch-based operations result in periodic high loads and subsequent over-design and increased capital cost. By destroying the hypochlorite in situ, within the scrubber recycle loop, the end of cycle concentration can be reduced and the load on the end-of-pipe hypochlorite destruction system lowered allowing an overall cost reduction. The reduced free chlorine concentration also leads to improved process safety, although increased heat removal is required. 

Fuel cell pressurization is typical of many optimization issues, in that there are many interrelated factors that can complicate the question of whether to pressurize the fuel cell. Pressurization improves process performance at the cost of providing the pressurization. Fundamentally, the question of pressurization is a trade-off between the improved performance (and/or reduced cell area) and the reduced piping volume, insulation, and heat loss compared to the increased parasitic load and capital cost of the compressor and pressure-rated equipment. However, other factors can further complicate the issue. To address this issue in more detail, pressurization for an MCFC system will be examined. 

The capital cost of air separation machinery is linked to both the size of the beds (which dictates the cost of piping valves), of course to molecular sieve inventory and to the size of the compressor required to run the process. A low product recovery may have little impact on the bed size factor but it has an enormous effect on the amount of gas required and on the cost of compressing that gas. Thus the recovery and bed size factors have direct links to the cost of capital and operations of air separation machines. 

The major costs involved in a home refrigerator are the capital costs of buying the compressor, the heating and cooling coils, the circulation pipes, and the expansion valves, as well as the yearly operating cost of electricity and maintenance. 

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