JPS6155030B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air separation device having a product oxygen gas pressure regulating device.

A conventional air separation device for extracting product gas oxygen will be explained with reference to FIG. It is introduced at the bottom of the tower. Oxygen and nitrogen are preliminarily rectified in the lower column of the double rectification column 3, and liquid nitrogen is extracted from the conduit 7 as a reflux liquid to the upper column. Further, liquid air is extracted from the lower part of the lower column through a conduit 4, passes through a hydrocarbon adsorber 5 and a heat exchanger 6, and is introduced into the middle part of the upper column.

The product nitrogen gas is extracted from the upper part of the lower column through a conduit 9, and the temperature is recovered to room temperature by the reversible heat exchanger 1, and then taken out. A part of the liquid oxygen accumulated in the main condenser is taken out through the conduit 11, and after being pressurized by the liquid acid circulation pump 12,
4, is returned to the main condenser via conduit 15.

On the other hand, product oxygen gas and impure nitrogen gas are taken out through conduit 8 and conduit 10, respectively.
The temperature is recovered to room temperature by the reversible heat exchanger 1 and taken out of the apparatus.

However, the conventional technology has the following problems. That is, if the product oxygen gas pressure is e.g. 2000
If mmAq becomes 5000mmAq, double rectifier 3
The pressure at the bottom of the upper tower is determined by the product oxygen gas pressure, so the pressure at the bottom of the upper tower is approximately
It will be 3000mmAq higher. At this time, if the temperature difference in the main condenser located in the middle of the double rectification column 3 is constant, when the pressure at the bottom of the upper column increases by 3000 mmAq, the saturation temperature and pressure of the two fluids exchanging heat in the main condenser From the relationship, the pressure at the upper part of the lower column of double rectification column 3 is approximately
It will be 0.9Kg/cm ² G higher.

This is because the conduit 2 that blows raw air into the lower tower is connected to the discharge side of the raw air compressor.
This will increase the discharge pressure of the raw material air compressor,
This will lead to an increase in the initial cost of the raw air compressor and a significant increase in power consumption, leading to an increase in running costs.

In addition, the design pressure of the equipment constituting the air separation apparatus, including the double rectification column 3, increases, resulting in increased costs and disadvantages such as the inability to use standard equipment.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide an air separation device having an excellent product oxygen gas pressure regulating device.

The present invention is an air separation device equipped with a line that circulates part of the liquid oxygen taken out from the main condenser of a double rectification column through a conduit through a liquid acid circulation pump, a circulation adsorption device, etc. A product that is equipped with a liquid level adjustment mechanism including a sub-condenser and a liquid level control valve for the sub-condenser on the outlet side of the vessel, and further includes a conduit and pressure control valve that supplies part of the raw air as a heating source for the sub-condenser. It is characterized by being provided with an oxygen gas pressure adjustment mechanism.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, the same parts as in FIG. 1 are indicated by the same symbols.

The raw air cooled to near the liquefaction point of the air in the reversible heat exchanger 1 is introduced into the lower part of the double rectification column 3 through the conduit 2. A part of the raw material air branched from the conduit 2 through the conduit 19 is supplied as a heating source to the sub-condenser 16, and after evaporating and condensing the necessary product oxygen gas in the sub-condenser 16, the product oxygen gas pressure is adjusted. It is introduced into the lower part of the double rectification column 3 through the valve 20.

Oxygen and nitrogen are preliminarily rectified in the lower column of the double rectification column 3, and liquid nitrogen is passed through the conduit 7 as a reflux liquid to the upper column.
extracted from Further, liquid air is extracted from the lower part of the lower column through a conduit 4, passes through a hydrocarbon adsorber 5 and a heat exchanger 6, and is introduced into the middle part of the upper column. The product nitrogen gas is extracted from the upper part of the lower column through conduit 9, and the impure nitrogen gas is extracted from the upper part of the upper column through conduit 10, and the temperature is recovered to room temperature by each reversible heat exchanger 1 and exits the apparatus. taken out.

On the other hand, a part of the liquid oxygen stored in the main condenser installed in the middle of the double rectification column 3 is transferred to the conduit 1.
1, and after being pressurized to a predetermined pressure by the liquid acid circulation pump 12, it is introduced into the circulation adsorption device 14, where the acetylene, etc. contained in the liquid oxygen is adsorbed and removed. , sub-condenser 1
By exchanging heat with the raw material air led through conduit 19, the amount of liquid oxygen corresponding to the amount of product oxygen gas is gasified, and the remaining liquid oxygen is passed through conduit 1.
7 and the liquid level control valve 18, and is returned to the main condenser of the double rectification column 3. Thus, the product oxygen gas is taken out from the upper part of the sub-condenser 16 via the conduit 8,
After the temperature is recovered to room temperature by the reversible heat exchanger 1, it is taken out of the apparatus.

The liquid level of the sub-condenser 16 is automatically adjusted by a liquid level regulator (LIC) and a liquid level control valve 18.
On the other hand, the product oxygen gas pressure can be set arbitrarily by changing the set value of the pressure indicating controller (PIC). It is automatically regulated by the control valve 20.

As described above, the present invention has the following effects.

(1) Since the product oxygen gas pressure can be adjusted arbitrarily without affecting the discharge pressure of the double rectification column or feed air compressor, the product oxygen gas can be heated to a pressure higher than the conventional pressure of 2000 mmAq. Even when taking out the raw material, there is no need to increase the discharge pressure of the raw material air compressor, and it is possible to significantly reduce initial costs and running costs.

(2) There is no need to increase the design pressure of the equipment that makes up the air separation device, and conventional standard equipment can be used, leading to significant cost reductions.

(3) The capacity of the main condenser of a double rectification tower can be reduced by the capacity of the sub-condenser, making the double rectification tower more compact, the cold storage tank more compact, and the need for cold storage materials reduced. This makes it possible to reduce the weight and cost of the entire device.

(4) Since the liquid oxygen in the sub-condenser exchanges heat with the feed air, the temperature difference between the two fluids undergoing heat exchange can be approximately three times larger than the temperature difference in the main condenser of a conventional double rectification column. As a result, the sub-condenser can be made very small.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a conventional air separation device for collecting product oxygen gas, and FIG. 2 is a system diagram showing an embodiment of the air separation device for collecting product oxygen gas according to the present invention. 1... Reversible heat exchanger, 2, 4, 7 to 11, 1
3, 15, 17, 19... conduit, 3... double rectification column, 5... hydrocarbon adsorber, 6... heat exchanger, 1
2...Liquid acid circulation pump, 14...Circulation adsorber, 1
6...Sub-condenser, 18...Liquid level control valve, 20...
Pressure control valve.

Claims (1)

[Claims] 1. In an air separation device in which part of the liquid oxygen taken out from the main condenser section of a double rectification column is circulated to the main condenser section via a liquid acid circulation pump, a circulation adsorption device, etc., the above-mentioned circulation adsorption device A sub-condenser and a liquid level adjustment mechanism that automatically adjusts the liquid level of the sub-condenser are provided on the outlet side, and a conduit through which raw air flows as a heat source to the sub-condenser and a pressure control mechanism are provided on the outlet side of the sub-condenser of the conduit. An air separation apparatus characterized in that a control valve is provided, and a pressure indicating controller for operating the pressure control valve is provided in a conduit for taking out product oxygen gas from the sub-condenser.