Fin fan coolers

The amine cooler is typically an air-cooled, fin-fan cooler, which low-er.s the lean amine temperature before it enters the absorber. The lean amine entering the absorber should be approximately 10°F warmer than the sour gas entering the absorber. Lower amine temperatures may cause the gas to cool in the absorber and thus condense hydrocarbon liquids. Higher temperatures would increase the amine vapor pressure and thus increase amine losses to the gas. The duty for the cooler can be calculated from the lean-amine flow rate, the lean-amine temperature leaving the rich/lean exchanger and the sour-gas inlet temperature. 

The second modification to the flowscheme is that steam condensate from the ammonia vaporizer has been fed directly into the vapour/liquid separator, from where it may be drawn for waste-heat boiler feed. This route is in preference to feeding the condensate (at 250°C) back into the deionized-water circuit. By re-routing to the vapour/liquid separator, the heat duty of the waste-heat boiler can be reduced, and hence its size and cost are lower. The duty on the deionized-water fin-fan cooler and the economizer throughput are reduced. Both of these modifications result in a lower capital cost. 

For low electricity costs ( 75% compared with the reference case). Cases IE and IG will be more attractive compared with the other cases. These cases are still attractive even with higher electricity cost (125% compared with the reference case), with a payback period of 0.88 years. As expected, a higher electricity price reduces the attractiveness of all cases. Waste LLP steam can be recovered economically from the steam condensate system. Alternatively, waste heat can be recovered as hot water from process streams. Petroleum refineries often discard a lot of waste heat through furnace stacks, fin-fan coolers and product coolers, which can be used to generate LLP steam (Reddy et al., 2013b). In such situations, where LLP steam is available at zero cost, a single-stage absorption chiller (Cases ID and IF) becomes feasible and attractive with a payback period of 0.93 years (Table 11.2). 

When cooling water is scarce, air is used for cooling and condensing liquid streams in fin-fan heat exchangers. A common configuration is shown in Figure 13.11. See, also, a video of an industrial fin-fan cooler on the CD-ROM that accompanies this text. The liquid to be cooled... 

As lower temperatures favor the absorption of CO by the Catacarb solution, I had expanded the capacity of the circulating Catacarb solution aerial fin-fan cooler to cool the absorber tower and thus reduce CO in the Hj product. Liz stood next to me at the panel when we started the Catacarb circulation pumps. I was totally confident. 

Pumps should not be located adjacent to critical, high-value equipment, under or adjacent to overhead fin fan coolers, or under main instrumentation and electrical cable runs. 

Check pressure drop between Fin-Fans and Trim Coolers... 

Spraying water on fin-fan air coolers is generally not a good idea. It is really effective only in dry climates with low humidity. The evaporation of water by the dry air cools the surface of the fins that is, the latent heat of vaporization of the water, robs sensible heat from the tubes. 

Deionized- water Cooler A finned fan-type cooler. would be sufficient to provide the estimated 300 kW cooling duty. 

The ion-exchange unit for treatment of scheme water to deionized water is outside the process flowsheet shown in Figure 4.1. The flowrate through this unit is 2338 kg, equal to the make-up water requirement. Also required is a fin/fan-type cooler for the circuit itself, so that the temperature of the return deionized-water stream can be lowered from 40°C to 20°C... 

Table 2.9 Revamp options for heat exchangers and fin fan (or air) coolers. Equipment - Objective Options...

Overhead Temperature In hot weather, the tower overhead fin fan condenser could be limited and thus the tower top temperature can go up. As a result, valuable components could be vaporized into overhead vapor leading to yield loss. There are a number of ways to reduce the overhead temperature such as increasing cooling water rate, turning on spare overhead fan for air cooler, and... 

FIGURE 3-3 Pressure survey indicates the need to clean fin-fan air cooler. 

Ambient air is compressed in a turbocharger, powered by the expansion of the hot pressurized exhaust gases. Following this first compression stage, the air is intercooled by a fin fan air cooler and fed into a second turbocharger. The high-pressure air is fed directly to the PEFC... 

In a used motor oil reprocessing facility, the vacuum tower precondenser consisted of a large fin-fan air cooler. Inlet conditions were 260°F and 80 mm Hg. Due to the contaminants in the used motor oil,... 

Liz said that I went deathly pale. I was soaked with sweat in the chilly control room. The operations chief and panel room operators beamed with pleasure. Confused, I asked them to turn on the last fan on the aerial fin-fan solution cooler. The absorber temperature dropped by 10°F and the CO in the hydrogen product went up from 3.5 to 4 percent CO. ... 

The catalyst was like a cold drink on a hot summer s day. 1 put all the variables I had changed in three weeks back to normal conditions. I turned on all the aerial cooler fin-fans. The CO dropped below 0.2 percent in the hydrogen product. 

Spraying water on fin-fan air coolers is generally not a good idea. It is really effective only in dry climates withlow humidity. The evaporation... 

In a used motor oil reprocessing facility, the vacuum tower precondenser consisted of a large fin-fan air cooler. Inlet conditions were 260°F and 80 mm Hg. Due to the contaminants in the used motor oil, this is a potentially very fouling service. Tube inserts, called turbulators (basically wire springs), were installed in the firmed tubes by the manufacturer. The initial performance was reported by our client to be good. However,... 

Oil coolers either dissipate the heat into a vv ater stream or the air. Water coolers (Fig, 29-85) are significantly more compact, but a supply of vv ater is required. Air coolers (Fig, 29-86) are large and require a fan that increases the air flow ov er the cooling fins,... 

Air coolers Tubes are 0.75-1.OOin. 00, total finned surface 15-20 sqft/sqft bare surface, U = 80-100 Btu/(hr)(sqft bare surface)(°F), fan power input 2-5 PIP/(MBtu/hr), approach 50°F or more. 

Loss of airflow through a finned tube air cooler bundle is a universal problem. The effect is to reduce the exchanger s cooling efficiency. To restore cooling, you might wish to try the Norm Lieberman method, which consists of reversing the polarity of the fan motor electric leads. The fan will now spin backward. Depending on the nature of the deposits, a portion of the accumulated dirt will be blown off the tubes— but all over the unit. Personnel observe this procedure from a safe distance. 

In such equipment the process fluid flows through finned tubes and cooling air is blown across them with fans. Figures 8.4(g) and (h) show the two possible arrangements. The economics of application of air coolers favors services that allow 25-40°F temperature difference between ambient air and process outlet. In the range above 10MBtu/(hr), air coolers can be economically competitive with water coolers when water of adequate quality is available in sufficient amount. 

Tubes are 0.75-1.00 in. OD, with 7-11 fins/in. and 0.5-0.625 in. high, with a total surface 15-20 times bare surface of the tube. Fans are 4-12ft/dia, develop pressures of 0.5-1.5in. water, and require power inputs of 2-5HP/MBtu/hr or about 7.5HP/ 100 sqft of exchanger cross section. Spacings of fans along the length of the equipment do not exceed 1.8 times the width of the cooler. Face velocities are about 10 ft/sec at a depth of three rows and 8 ft/sec at a depth of six rows. 

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