| 摘要 |
A method maintains, in a compressed gas dryer, working through condensation of moisture contained in the air and with dryer thermal load demands, an operation that keeps the temperature of the evaporator, near the outflow of the compressed air, in range between a value sufficiently high to avoid freezing the moisture in the compressed air and a value sufficiently low to avoid compromising the effect of moisture condensation generated by the decreased temperature. This objective is achieved with a compressor by-pass conduit on which is mounted a selectively controllable adjusting valve. The operation includes: measurement of the evaporation temperature (Tev), and verification the temperature is higher than a preset value (Set_Tev); starting the compressor; opening the valve for a preset time, and then closing it; verification that the temperature is higher than a preset value; if the time elapsed is longer than a predetermined time, then the valve is opened. |
| 主权项 |
1. Method for gas drying, particularly of a compressed gas, comprising the steps of:
introducing the gas to be dried into a second conduit which includes a condensation separator which is arranged in a second branch of a second heat exchanger having a respective first branch including an evaporator, the first branch forming a portion of a cooling circuit circulating a cooling fluid means and obtained by a first conduit, said evaporator, a compressor and a by-pass conduit capable of connecting the suction side to the output side of said compressor, said by-pass conduit comprising a fixed valve and a second control valve capable of being selectively closed or opened, and command and control means configured to: selectively command the closure or opening of said second control valve, and selectively command the stop and the start of said compressor, so that said cooling fluid means flowing out from said compressor is selectively directed with said second control valve open across said by-pass circuit and back to the suction side of said compressor, or the cooling fluid means is fully directed with said second control valve closed into said first conduit according to the commands processed and sent by said command and control means, define a minimum time interval length between two successive compressor starts, wherein the method includes the following steps: defining and recording a time moment of the method starting, measuring the evaporation temperature, or a different but correlated quantity, verifying said measured evaporation temperature or said different but correlated quantity is higher than a first pre-defined temperature or correlated quantity by comparing said measured evaporation temperature or correlated quantity and said first pre-defined temperature or correlated quantity, and when said measured evaporation temperature or the correlated quantity is higher than said first pre-defined temperature, or correlated quantity, then starting said compressor, and opening said second valve for a pre-defined time length; and thereafter closing said second valve, measuring the evaporation temperature or the different but correlated quantity, checking that said measured evaporation temperature or the correlated quantity is not higher than a second pre-defined temperature or correlated quantity, measuring the time length from the method beginning, and subsequently checking whether the condition that the time length passed from said method beginning is higher than said minimum time interval length. |
