JPS6246784B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the inlet temperature of a gas bearing expansion turbine in an expansion turbine used as a cold generation source in a cryogenic air separation device or a device for liquefying helium gas, hydrogen gas, etc. be.

FIG. 1 is a system diagram around a gas bearing expansion turbine of a cryogenic air separation device using a conventional gas bearing expansion turbine as a cold generation source.

The evaporated air at the saturation temperature is extracted from the upper part of the condenser 1, passed through a gas-liquid separator 2, and then passed through an air heat exchanger 3 to recover its temperature, and then sent to a gas bearing expansion turbine (hereinafter referred to as expansion turbine) 4. The air is then adiabatically expanded in the expansion turbine 4 to lower its temperature, and then passed through the air heat exchanger 3 again for heat exchange. Also,
The interlock for the expansion turbine 4 includes one that detects the turbine rotational speed with a tachometer oscillator 5 and closes an emergency shutoff valve 6 provided at the inlet pipe of the expansion turbine 4 when overspeed occurs.
The emergency shutoff valve 6 closes when the temperature at the expansion turbine inlet of the processed air falls below a set value (the optimal expansion turbine inlet temperature at which the processed air does not liquefy inside the expansion turbine) using a temperature detector 7 installed in the inlet piping. be. In particular, in the case of a gas bearing expansion turbine, since the bearing load capacity is relatively small, if the processing air condenses inside the turbine due to a drop in the inlet temperature, the rotor will become unbalanced and the bearing burnout is likely to occur. The same applies if air accompanied by condensed liquid enters. For this reason, the above-mentioned interlock is provided, and for example, the inlet temperature of the expansion turbine 4 is monitored, and when the temperature falls below the above-mentioned set value, the emergency shutoff valve 6 at the inlet of the expansion turbine 4 is closed, and the rotation of the expansion turbine 4 is stopped. However, in this case, the expansion turbine 4
Since the rotation stops completely, it takes a lot of time to restart it. Further, the inlet temperature of the expansion turbine 4 can be controlled by temperature balance operation of the air heat exchanger 3, or by
This can be done by lowering the condensate liquid level in the condenser 1 sufficiently to reduce the entrainment rate of mist in the evaporated air extracted from the upper part of the condenser 1, but this will reduce the capacity of the condenser 1. However, this type of operation also had the disadvantage that it took a lot of time to balance the heat of the entire plant.

The present invention is aimed at eliminating the drawbacks of the above-mentioned conventional technology.The inlet temperature of the gas bearing expansion turbine is adjusted using a three-way temperature control valve, and the temperature is controlled to the optimum temperature so that the processed air does not liquefy inside the gas bearing expansion turbine. This provides a method to do so.

One embodiment of the present invention will be described with reference to FIG. 2. In the figure, a part of the air fed from the gas-liquid separator 2 is temperature-recovered by an air heat exchanger 3 and a temperature control three-way valve 8
In addition, the other part is similarly supplied to the temperature control three-way valve 8 through the bypass circuit 9, and then the emergency cutoff valve 6
The gas is supplied to a gas bearing expansion turbine (hereinafter abbreviated as expansion turbine) 4 through the gas bearing expansion turbine. The supplied processing air undergoes adiabatic expansion in the expansion turbine 4 to lower its temperature, and then passes through the air heat exchanger 3 again for heat exchange. Note that the temperature control three-way valve 8 is operated by a signal from the temperature detector 7.

In the air heat exchanger 3, the heat transfer area of the turbine processing air line 10 is made larger than that of the conventional one. Always maintain the temperature above the optimum expansion turbine inlet temperature (at which no liquefaction occurs). Therefore, in this case, the inlet temperature of the expansion turbine 4 will exceed the set value, so the temperature control three-way valve 8 is controlled and operated by the signal from the temperature detector 7, and the bypass circuit 10 is activated.
This air is mixed with the air fed from the air heat exchanger 3 while adjusting the amount of low-temperature air fed from the air heat exchanger 3, so that the inlet temperature of the expansion turbine 4 is always adjusted to the set value.

As explained above, the present invention increases the heat transfer area of the air heat exchanger turbine processing air line and adjusts the inlet temperature of the gas bearing expansion turbine to an appropriate temperature using a three-way temperature control valve. It is possible to prevent an emergency stop of the expansion turbine and a bearing seizure accident, and it has the effect of improving the continuous operability and reliability of cryogenic air separation equipment, etc.

[Brief explanation of the drawing]

FIG. 1 is a system diagram around a gas bearing expansion turbine in a conventional cryogenic air separation device, and FIG. 2 is a system diagram around a gas bearing expansion turbine in an embodiment of a cryogenic air separation device according to the present invention. . 1... Condenser, 2... Gas-liquid separator, 3... Air heat exchanger, 4... Gas bearing expansion turbine, 5... Tachometer oscillator, 6... Emergency shutoff valve, 7... Temperature detector, 8...Temperature control three-way valve, 9...Bypass circuit, 10...Turbine processing air line.

Claims (1)

[Claims] 1. In a gas bearing expansion turbine used in a cryogenic air separation device, etc., the low temperature gas from the gas-liquid separator is recovered in a heat exchanger to a temperature above which it will not liquefy inside the gas bearing expansion turbine. , the low-temperature gas from the gas-liquid separator is appropriately mixed with a temperature control three-way valve operated by a signal from the gas-bearing expansion turbine inlet temperature detector, so that the process gas is optimally prevented from liquefying inside the gas-bearing expansion turbine. A method for controlling the inlet temperature of a gas bearing expansion turbine, characterized in that the temperature is adjusted to a temperature of .