Chilling systems

Cooper, K W. and R. W. Erth, Centrifugal Water Chilling Systems Focus on Off-Design Performance, Heating/Piping/Air Conditioning, p. 63, Jan. (1978). 

Centrifugal Water Chilling Systems Focus on Off-Design Performance... 

Chamber Tests. Edney and his coworkers (14) have conducted some interesting tests using a rectangular flow channel through which various humidified polluted air mixtures are passed, with corrosion test samples mounted on the side walls and equipped with a chilling system to induce condensation and hence absorption of SO2 on the test samples. Their test conditions are about 3 m/s air flow through a duct 13 x 13 cm. in cross-section. There is a smaller duct section upstream. According to pipe flow results, the flow should be turbulent under these conditions but not fully deve-... 

In arid zones where water is scarce, the cooling towers can be replaced by thermal chilling systems and the chilled water can be retained in a closed cycle of DM water. 

Absence of a chain of reactors fitted with chilling systems to prevent runaway reactions between oleum and urea. 

The synthesis gas makeup enters the loop upstream of the chilling system, is cooled down, and then mixed with the loop gas upstream of the ammonia separator. 

Chilled water lines (refrigeration system or well)... 

Fig. 38. Caustic purification system a, 50% caustic feed tank b, 50% caustic feed pumps c, caustic feed preheater d, amonia feed pumps e, ammonia feed preheater f, extractor g, trim heater h, ammonia subcooler i, stripper condenser j, anhydrous ammonia storage tank k, primary flash tank 1, evaporator reboiler m, evaporator n, caustic product transfer pumps o, purified caustic product cooler p, purified caustic storage tank q, ammonia stripper r, purified caustic transfer pumps t, overheads condenser u, evaporator v, evaporator vacuum pump w, aqueous storage ammonia tank x, ammonia scmbber y, scmbber condenser 2, ammonia recirculating pump aa, ammonia recycle pump. CW stands for chilled water.

Fum ric Acid. Eumaric acid [110-17-8] C H O, is unique in its low solubiUty in cold water and slow rate of solution, making it ideal for use in chilled biscuit leavening systems and for dry pudding mixes and beverage powders. It is also used for gelatin desserts, pie filling, fmit juices, and wine. Eumaric acid is produced by the acid-catalyzed isomerization of maleic acid (8,9) (see Maleic anhydride, maleic acid, and fumaric acid). 

Cooling is routinely appHed, either with ambient process water if THF is the solvent or with chilled brine if diethyl ether is used. Since Grignard reagents are particularly reactive with water, Hquid hydrocarbon coolants may be preferred, to eliminate the risk that could arise from a cooling-system leak. 

Polyethylene. This is essentially a closed-ceU insulation manufactured at 448 2 K by an extmsion process. A blowing agent and nucleating agent are employed to control the ceU size, and primary use is in insulating pipelines for hot and chilled water lines, air conditioning, and processing systems. 

In the case of l,4-ben2oquinone, the product is steam-distilled, chilled, and obtained in high yield and purity. Direct oxidation of the appropriate unoxygenated hydrocarbon has been described for a large number of ring systems, but is generally utilized only for the polynuclear quinones without side chains. A representative sample of quinone uses is given in Table 5. 

Once the green, nonalum modifications of the chromium ion have formed, reversion to the hexaaquo form on cooling is sufficiendy slow that on chilling to 5°C a cmde ferrous ammonium sulfate can be crystallised, removing neady all the iron from the system. This cmde iron salt is treated with makeup ammonium sulfate, heated again to retain the chromium impurities in the green noncrystallisahle form, and then cooled to separate the bulk of the iron as a technical ferrous ammonium sulfate, which is sold for fertiliser and other purposes. The mother Hquor from this crystallisation is returned to the filtration step. 

Predemethanization. The conventional design employs a single-step multiple feed tower. Utilization of a second tower upstream of the existing primary tower reduces the load on the primary tower. This reduces the propylene refrigeration power and reduces the propylene chilling loads. This approach is typically uneconomical with low pressure demethanizers, but has been combined with high pressure demethanizer systems by some Hcensors. 

Ejector (steam-jet) refrigeration systems are used for similar apph-cations, when chilled water-outlet temperature is relatively high, when relatively cool condensing water and cheap steam at 7 bar are available, and for similar high duties (0.3-5 MW). Even though these systems usually have low first and maintenance costs, there are not many steam-jet systems running. 

Evaporator is the heat exchanger where refrigerant (water) evaporates (being sprayed over the tubes) due to low pressure in the vessel. Evaporation chills water flow inside the tubes that bring heat from the external system to be cooled. 

Despite being simple, rugged, reliable, requiring low maintenance, low cost, and vibration free, steam-jet systems are not widely accepted in water chilling for air-conditioning due to characteristics of the cycle,... 

Capacity Control The simplest way to regulate the capacity of most steam vacuum refrigeration systems is to furnish several primary boosters in parallel and operate only those required to handle the heat load. It is not uncommon to have as many as four main boosters on larger units for capacity variation. A simple automatic on-off type of control may be used for this purpose. By sensing the chilled-water temperature leaving the flash tank, a controller can turn steam on and off to each ejector as required. 

The thermocycle system can be operated only when condensing water is available at a temperature lower than the required chilled-water-supply temperature. Modifications for a centrifugal refrigeration unit include the installation of a small liqmd-refrigerant pump, cooler spray header nozzles, and a vapor bypass line between the cooler and the condenser. Without the compressor operating, a thermocycle capacity up to 35 percent of the refrigeration-unit rating can be produced. 

An Oslo surface-cooled crystallizer is illustrated in Fig. 18-71. Supersaturation is developed in the circulated liquor by chilling in the cooler H. This supersaturated liquor is contacted with the suspension of ciystals in the suspension chamber at E. At the top of the suspension chamber a stream of mother hquor D can be removed to be used for fines removal and destruction. This feature can be added on either type of equipment. Fine ciystals withdrawn from the top of the suspension are destroyed, thereby reducing the overall number of ciys-tals in the system and increasing the particle size of the remaining product ciystals. 

For research of alloys in the liquid state the chemical analysis can be applied only then, when high-temperature samples sharply to chill, that is to temper. But it can cause changes in the state of the system. That is why it is the best to determine composition of alloys in the liquid state. 

Thermal Energy Storage Systems—These are intermittent use systems where the cold is produced off-peak and then used to chill the inlet air during the hot hours of the day. 

Direct expansion is also possible wherein the refrigerant is used to chill the incoming air directly without the chilled water circuit. Ammonia, which is an excellent refrigerant, is used in this sort of application. Special alarm systems would have to be utilized to detect the loss of the refrigerant into the combustion air and to shut down and evacuate the refrigeration system. 

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