Estimating heat exchangers

A flow of I kg/s of an organic liquid of heat capacity 2.0 kJ/kg K is cooled from 350 to 330 K by a stream of water flowing countcrcurrently through a douhle-pipe heat exchanger. Estimate the effectiveness of the unit if the water enters the exchanger at 290 K and leaves at 320 K. 

One luuidred kmol per hour of subcooled liquid at 300 K and 3 bar is superheated to 500 K in a steady-flow heat exchanger. Estimate tlie exchanger duty (in kW) for one of tile following ... 

For a large insulated, countercurrent heat exchanger, estimate the number of moles of N2 that can be continuously heated from 298 to 353 K by two moles of NO2 entering at 373 K and leaving at 298 K if... 

Explosion-bonded metals are produced by several manufacturers in the United States, Europe, and Japan. The chemical industry is the principal consumer of explosion-bonded metals which are used in the constmction of clad reaction vessels and heat-exchanger tube sheets for corrosion-resistant service. The primary market segments for explosion-bonded metals are for corrosion-resistant pressure vessels, tube sheets for heat exchangers, electrical transition joints, and stmctural transition joints. Total world markets for explosion-clad metals are estimated to fluctuate between 30 x 10 to 60 x 10 annually. 

Pumping and heat exchange form part of a functional unit. Tn-process storage is ignored, but large storage requirements for raw materials, intermediates, or products are usually estimated separately. Sometimes there are difficiilties in the identification and definition of the functional units involved in a process. 

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. 

Knowledge of the composition of coal ash is usehil for estimating and predicting coal performance in coke making and, to a hmited extent, the folding and corrosion of heat-exchange surfaces in pidverized-coal-fired furnaces. 

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,... 

Chapter 1 provides a summary of important equations for estimating the terminal temperatures in a heat exchanger. Here we formalize a short estimating procedure for a countercurrent flow situation. Assume that a specifier of a heat exchanger has defined a preliminary sizing of the unit. The system requires heat and material balances. 

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,... 

Another possibility is dropping into the heat exchanger bay the 100 ton heat exchanger to cause a primary or secondary LCXZA. If irradiated fuel were still in the reactor, melting could occur. Heat exchangers have been removed with hot fuel in the reactor (at least twice since 1971). This scenario was estimated to be -- lE-4/y and procedures were changed to eliminate it... 

It is very difficult to estimate the magnitude of the contact conductance G. Normally the total conductance of the heat exchanger is determined, and G - is calculated from Eq. (9.48). Only in the case that rhe plate fins are welded to the pipes with a metallurgical contact is the contact conductance infinite, leading to zero contact resistance, that is 1 /G,. = 0. 

Chapter 3 of Volume 1 discusses many of the basic properties of gas and methods presented for calculating them. Chapter 6 of Volume 1 contains a brief discussion of heat transfer and an equation to estimate the heat required to change the temperature of a liquid. This chapter discusses heat transfer theory in more detail. The concepts discussed in this chapter can be used to predict more accurately the required heat duty for oil treating, as well as to size heat exchangers for oil and water. 

Mulvihill, R. J. and Y. G. Mody. Failure Rate Distribution and Mean Time to Repair Estimates for Heat Exchanger and Condenser. SAN/RA50239, Pickard, Lowe and Garrick, Inc., November 1981. 

Pressure loss in a piping system (not including the tanks, heat exchangers, distillation columns, etc.) is usually expressed in units oi feet of flowing fluid, or the equivalent converted to pounds per square inch. Some published pressure loss data is expressed as per 100 equivalent feet of the size pipe being used or estimated. 

Ganapathy presents a shortcut technique for estimating heat exchanger tube wall temperature, which so often is needed in establishing the fluid film temperature at the tube wall ... 

Estimating Overall Heat Transfer Rates, Uq, for Longitudinal Finned Heat Exchangers... 

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