Adsorption capital cost

The cost effectiveness of an adsorption cycle machine depends both on the COP, which will affect the operating costs and also on its size, which will influence the capital cost. The COP in a particular application will be both a function of the adsorbent properties and of the cycle used. Complex cycles described below can deliver high COP s but require more heat transfer area and are therefore larger, leading to a higher capital cost. There is a compromise between efficiency and complexity which determines the optimum design. 

Cascade adsorption will increase the initial capital cost you should evaluate whether the increase in solvent recovery justifies the added expense. 

The main factors in the design of an adsorption system are the (1) Carbon consumption - The amount of earbon required to treat the liquid or gas, normally expressed per unit of the fluid treated and (2) Contact time - For a fixed flow rate, the contact time is directly proportional to the volume of carbon and is the main factor influencing the size of the adsorption system and capital cost. 

The U.S. Department of Energy s (DOE s) Los Alamos National Laboratory (LANE) conducted a costs analysis of in situ air stripping technology based on data from a 1995 demonstration at the DOE s Savannah River Site (SRS) near Aiken, South Carolina. Capital costs were annualized over an estimated 10-year equipment life. Carbon adsorption was included for off-gas treatment. The total cost of the demonstration was 15.59/lb of VOC removed. Table 1 shows a more detailed breakdown of these costs (D15726Q D188083). 

Solvent recovery systems would also necessitate the specification of condenser duties, distillation tower sizes, holding tanks, piping, and valves. It is important to note that the engineering design of an adsorption system should be based on pilot data for the particular system. Information can usually be obtained directly from the adsorbent manufacturer. The overall size of the unit is determined primarily by economic considerations, balancing the operating costs against the capital costs. 

Operating and Capital Costs of South Lake Tahoe Carbon Adsorption System (1969-1970) ... 

Paper LLC and adsorption TLC are basic parts of all major complex methods in current use and likely to remain so. Capital cost is small, risk of obsolescence is small, and training investment is minimal. One technician should specialize in it, and all others should be familiar with it. Simple columns mainly for adsorption chromatography are necessary for the Brown method and are potentially or actually useful for many methods. The simpler techniques are easily mastered, but for some, considerable know-how is needed, most of which can be gleaned from Brown s papers and symposia discussions (E2, G8, L8, P3). 

Adsorption capacity (or loading) is probably the most important characteristic of an adsorbent. More detail is provided in Section 14.3.2. The loading is the amount of adsorbate taken up by the adsorbent, per unit mass (or volume) of the adsorbent, and it depends on the fluid-phase concentration, the temperature, and other conditions (especially the initial condition of the adsorbent). Typically, adsorption capacity data are plotted as isotherms (loading of adsorbate on the adsorbent versus fluid-phase adsorbate concentration at constant temperature), isosteres, isobars, and others mentioned later. Examples are shown in Figures 14.1 through 14.3. Adsorption capacity is of paramount importance to the capital cost, because it sets the amount of adsorbent required and also the volume of the adsorber vessels the costs of both are significant if not dominant. When comparing alternate adsorbents, it is fair to express their capacity on a per unit volume basis, since that fixes... 

Adsorption processes have a number of competitors, including primarily distillation, extractive and azeotropic distillation, absorption, solvent extraction, and, more recently, membrane-besed processes. Vapur-liquid-hamd processes nad, in particular, distillation are especially formidable competitor because of their relatively simple flowsheets, Thus, if a separation can be performed easily by distillation, it will usually be tbe process of choice, based on relatively low capital costs and tolerable, if not low. enetgy costs. In addition, systems of distillation columns can oftentimes be energy integrated lo efleet lower energy costs per unit of feed processed than for siand-alone columns. 

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