Systems refrigerated inlet

Evaporative methods-direct water fogging Refrigerated inlet cooling systems-ical refrigeration... 

Combination of evaporative and refrigerated inlet systems—The use of evaporative coolers to assist the chiller system to attain lower temperatures of the inlet air. 

Refrigerated Inlets for the Gas Turbines. The refrigerated inlets are more effeetive than the previous evaporative eooling systems as they ean lower the temperatures by about 45-55 °F (25-30 °C). Two teehniques for refrigerating the inlet of a gas turbine are vapor eompression (meehanieal refrigeration) and absorption refrigeration. 

Figure 2-36. Meohanioal refrigerated inlet system used to oool the inlet air of the gas turbine.

Fig. 1. Components of a refrigeration system A, condenser outlet B, evaporator inlet C, evaporator outlet D, compressor discharge.

FIG. 11-98 Performance of complete refrigeration system (1), when there is reduction in heat load (2), and when for the same ambient (or inlet in evaporator) evaporation temperature is maintained constant hy reducing capacity of compressor/condenser part (3). 

In pre-boost applications, the turboexpander discharge pressure is considerably lower than the compressor inlet pressure. This situation requires special consideration when designing the turboexpander and auxiliary systems. In pre-boost designs, compressing the gas to a higher pressure produces more refrigeration in the turboexpander. Figure 3-9 shows a cross-section of an expander-compressor unit. 

When produced from natural gas the synthesis gas will be impure, containing up to 5 per cent inerts, mainly methane and argon. The reaction equilibrium and rate are favoured by high pressure. The conversion is low, about 15 per cent and so, after removal of the ammonia produced, the gas is recycled to the converter inlet. A typical process would consist of a converter (reactor) operating at 350 bar a refrigerated system to condense out the ammonia product from the recycle loop and compressors to compress the feed and recycle gas. A purge is taken from the recycle loop to keep the inert concentration in the recycle gas at an acceptable level. 

While refrigeration technologies can provide a near-constant GT inlet air temperature, and thus a nearly constant GT power output, refrigeration TIC systems are significantly more expensive than evaporative systems. However, the incremental net power output from the refrigeration system, when measured on a unit cost basis ( per kWe),... 

FIG. 24-65 Mechanical refrigeration TIC systems utilizing chilled water for cooling turbine inlet air, and cooling towers to reject the waste heat into the environment, account for the majority of refrigeration TIC systems sold. 

An ideal Brayton refrigeration system uses air as a refrigerant. The pressure and temperature of air at compressor inlet are 14.7 psia and 100°F. The pressure and temperature of air at the turbine inlet are 60 psia and 260°F. The mass rate of air flow is 0.031bm/sec. Determine (a) the cooling load, (b) the compressor power required, (c) the turbine power produced, and (d) the cycle COP. 

Economics The advantages of this process are low equipment costs (viz. the deethanizer system and ethylene/ethane separation) and reliability of the acetylene hydrogenation due to low excess hydrogen at the reactor inlet. The refrigeration compressor benefits from low specific power and suction volume, while the cracked-gas compressor processes above-ambient-temperature gas. 

Many effective control schemes have been established over the years for individual chemical units (Shinskey, 1988), For example, a tubular reactor usually requires control of inlet temperature. High-temperature endothermic reactions typically have a control system to adjust the fuel flowrate to a furnace supplying energy to the reactor. Crystallizers require manipulation of refrigeration load to control temperatui e. Oxygen concentration in the stack gas from a furnace is controlled to prevent excess fuel usage. Liquid solvent feed flow to an absorber is controlled as some ratio to the gas feed. We deal with the control of various unit operations in Chaps. 4 through 7. 

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