초록 ▼

An improved dryer (10) and drying methods are provided which increase overall dryer efficiency by maintaining substantially constant output air stream adiabatic saturation ratio and temperature values during the course of drying, notwithstanding the occurrence of upset conditions. The dryer (10) inc

An improved dryer (10) and drying methods are provided which increase overall dryer efficiency by maintaining substantially constant output air stream adiabatic saturation ratio and temperature values during the course of drying, notwithstanding the occurrence of upset conditions. The dryer (10) includes a dryer body (12), an input air heater assembly (14) including an air heater (32), and a control assembly (18). The dryer body (12) has a drying zone (30), with product inputs and outputs (20, 22) as well as an input (26) for a heated air stream and an output (28) for the cooled, moisture-laden output air stream. The dryer control assembly (18) includes temperature and humidity sensors (48, 50) coupled to controllers (54, 60) and a PLC (66). The controller (54) is coupled with an exhaust fan/damper unit (46) while controller (60) is connected with a fuel valve (36). In operation, the temperature and humidity of the output air stream are continuously measured by the sensors (48, 50), and the controllers (54, 60, 66) are operable to adjust the exhaust fan/damper unit (46) to regulate the relative proportion of output air exhausted to the atmosphere and recycled via conduit (52) for mixing with the input air stream, and also regulate the energy input to the dryer. Maintaining a substantially constant output air stream adiabatic saturation ratio and temperature allows dryer operation at significantly higher efficiencies as compared with prior systems.

대표청구항 ▼

1. A method of drying an initially wet product having a moisture level, comprising the steps of:providing a stream of input air having input temperature and humidity levels; heating the input air stream to a desired temperature; contacting the heated input air stream and said initially wet product i

1. A method of drying an initially wet product having a moisture level, comprising the steps of:providing a stream of input air having input temperature and humidity levels; heating the input air stream to a desired temperature; contacting the heated input air stream and said initially wet product in a drying zone to give a dried product and an output air stream; determining the temperature and humidity of said output air stream; and maintaining the adiabatic saturation ratio and the temperature of said output air stream at predetermined, substantially constant levels during said drying, notwithstanding changes in a parameter selected from the group consisting of said input air temperature level, input air humidity level, said initially wet product moisture level, and combinations thereof, said maintaining step comprising the steps of recycling a first portion of said output air stream back to said input air stream for mixing therewith, exhausting a second portion of said output air stream to the atmosphere, and adjusting the energy input to the dryer, in response to said determining step.