JP2001221399A - Gas supplying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas supplying method for supplying boosted gas through a high-pressure gas holder and a low-pressure gas holder. SOLUTION: A flow control valve for gas is provided on the inlet side of a low-pressure gas holder. When pressure of the low-pressure gas holder is less than a lower limit set value, the flow control valve is opened to fill gas. When pressure of the low-pressure gas holder is more than pressure of a high- pressure gas holder and also when pressure of the low-pressure gas holder is not less than the lower limit set value, the flow control valve is opened to supply gas of the low-pressure gas holder to the high-pressure gas holder. When pressure of the low-pressure gas holder is not more than pressure of high-pressure gas holder and also when pressure of the low-pressure gas holder is not less than the lower limit set value, the flow control valve is closed to feed gas to only a low-pressure gas using facility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas supply method in a gas supply line for supplying gas to each equipment via a high-pressure gas holder for high-pressure gas equipment and a low-pressure gas holder for low-pressure gas equipment.

[0002]

2. Description of the Related Art In an integrated steel mill, various gases are used. For example, a large amount of oxygen gas is used for production in a blast furnace, a converter and the like. FIG. 1 schematically shows an example of an oxygen gas supply line used in an integrated steelworks.

The air taken in from the atmosphere is compressed by an air compressor 1, cooled in a washing cooling tower 2, passed through a molecular sieve in a molecular sieve adsorber 3, and purified in a rectifying tower in a cold box 4. To finally separate oxygen.
Then, the pressure is increased (compressed) by the oxygen compressor 5 to obtain a compressed oxygen gas having a required pressure. The compressed oxygen gas obtained here is
In accordance with the working pressure of the supply destination, it is supplied to and stored in two holders (gas tanks) of high pressure and low pressure.

An oxygen gas is supplied from a low-pressure gas holder 9 to a low-pressure gas facility 12 represented by a blast furnace, and an oxygen gas is supplied from a high-pressure gas holder 7 to a high-pressure gas facility 13 represented by a converter. Is supplied. Then, the above-described compressed oxygen is adjusted by the low-pressure gas holder 9 and the high-pressure gas holder 7 to a pressure required in each gas use facility. Here, a flow control valve 8 is attached to the entry side of the low-pressure gas holder 9. Reference numeral 6 denotes an oxygen release valve. The sequence controller 11 receives the pressure values of the low-pressure gas holder 9 and the high-pressure gas holder 7 measured by the pressure gauges 10a and 10b, and controls the flow control valve 8 and the oxygen release valve 6 based on the pressure values. Done.

[0005] The amount of compressed oxygen gas is controlled and produced so as to always be optimal in accordance with the operation of the equipment to be used. By reducing the number of operating rectification towers,
Make adjustments to minimize the cost of power consumption.
However, the rectification tower is a device that separates air while strictly controlling the equilibrium balance between liquid and vapor on the rectification plate in the tower. Requires at least about 3 hours. For this reason, it is practically impossible to temporarily stop the rectification tower or change the load due to a short stop (for example, about 30 to 180 minutes) on the equipment side.

[0006] The rectified oxygen gas is compressed by the oxygen compressor 5 and supplied at a required gas pressure. Usually, discontinuous operation is performed, as represented by a converter. Therefore, in order to secure a buffer at the time of factory shutdown or load change and to provide a stable supply,
The gas holder is provided on the gas supply line.

As described above, two types of gas holders, a low-pressure gas holder 9 and a high-pressure gas holder 7, are provided corresponding to the gas use equipment. The high-pressure gas holder 7 provided on the side of the high-pressure gas use equipment 13 such as a converter is operated in a high-pressure region of, for example, an upper limit set value of 2.16 MPa and a lower limit set value of 1.57 MPa. Usually, it is supplied continuously, and the holder pressure is always in a high pressure state.

On the other hand, a low pressure gas holder 9 provided on the low pressure gas use equipment 12 side such as a blast furnace has a flow control valve 8 at its inlet side.
Is arranged. Then, the operation is such that the flow control valve 8 is closed in a normal state except for an emergency in which the holder pressure is lower than the lower limit set value, and the gas stored in the low-pressure gas holder 9 is supplied only to the low-pressure gas use facility 12 side. So that the pressure is constantly reduced to the low pressure side. The low-pressure gas holder 9 has, for example, an upper limit set value of 1.86 MPa and a lower limit set value of 0.98
Operation is performed in the range of MPa. Note that the specifications of the gas holder itself are usually the same for both the low-pressure gas holder and the high-pressure gas holder, and the upper limit set value, which is the withstand pressure in the standard, is about 2.35 MPa.

Here, the high pressure gas holder 7 becomes full,
When the pressure is equal to or greater than the upper limit set value, the low pressure gas holder 9 is used as a backup for the high pressure gas holder 7 and the flow control valve 8 is opened to collect the excess gas in the high pressure gas holder. This is called radiation collection. And the low pressure gas holder 9
When both the high pressure gas holder 7 and the high pressure gas holder 7 are full, the oxygen is released from the oxygen release valve 6 to the atmosphere.

The low pressure gas holder 9 is characterized in that the pressure operation width is wider than that of the high pressure gas holder 7. That is,
Since the storable capacity of the compressible gas is determined by (pressure width ΔP × gas holder volume V), the low-pressure gas holder 9 having a wide pressure width up to the upper limit set value stores a larger amount of gas than the high-pressure gas holder 7. can do. The oxygen gas supply method that has been used in integrated steelworks
A description will be given based on FIG.

FIG. 4A is a graph showing a trend of operation in a converter, a smelting reduction furnace, a decarburization furnace, etc., which are high-pressure gas-using facilities, that is, a trend of oxygen consumption. FIG.
The vertical axis of (a) indicates the oxygen consumption in each furnace.
The blast furnace, which is a facility using low-pressure gas, always consumes a substantially constant amount of oxygen gas. FIG. 4B shows the trend of the holder pressure of the high-pressure gas holder and the low-pressure gas holder in the above-mentioned operation state. Here, the upper limit of the pressure resistance of each gas holder is 2.35 MPa. The lower limit of the high pressure gas holder pressure is 1.57MPa, and the lower limit of the low pressure gas holder pressure is 0.69MPa.
Is defined.

The high-pressure gas holder pressure fluctuates greatly depending on the operation of the converter and the like, and rises to the upper limit of the pressure resistance when the operation load is reduced. Here, when the high-pressure gas holder pressure reaches the upper limit of the pressure resistance, the flow control valve on the low-pressure gas holder inlet side is opened, and the radiation collection to the low-pressure gas holder is performed. Then, when both the high-pressure gas holder and the low-pressure gas holder are full, the oxygen release valve is opened, and atmospheric release is performed.

[0013]

However, in the above-mentioned conventional gas supply method, as shown by (*) in FIG. 4B, the low-pressure gas holder pressure may be higher than the high-pressure gas holder pressure. There is a problem that it often occurs.
Such a state is that excess gas that is not used is stored in the low-pressure gas holder, and a large waste is generated in the gas storage capacity of the entire gas supply line.

An object of the present invention is to realize optimization of gas storage capacity in a gas supply line without causing such waste in gas storage capacity.

[0015]

SUMMARY OF THE INVENTION The present invention provides a low-pressure gas holder having a flow control valve for supplying a pressurized gas to a high-pressure gas-using facility via a high-pressure gas holder and controlling a flow rate of the gas at a gas inlet side. A gas supply method for supplying to the low-pressure gas-using equipment via the above, wherein the relationship between the pressure of the low-pressure gas holder and the pressure of the high-pressure gas holder is (low-pressure gas holder pressure)> (high-pressure gas holder pressure), and
When the pressure of the low-pressure gas holder is higher than the lower limit set value,
By opening the flow control valve, the gas in the low-pressure gas holder is also supplied to the high-pressure gas holder, and (pressure of the low-pressure gas holder) ≦
(Pressure of the high-pressure gas holder) and when the pressure of the low-pressure gas holder is equal to or higher than the lower limit set value, the flow rate control valve is closed, and the gas of the low-pressure gas holder is supplied only to the equipment using the low-pressure gas. The above problem has been solved by a gas supply method characterized by the above.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the gas supply method of the present invention will be described with reference to Table 1.

[0017]

[Table 1]

Table 1 shows a matrix of the gas supply method of the present invention applied to the oxygen gas supply line in the integrated steelworks shown in FIG. In the table, stratification is performed by taking the pressure of the low-pressure gas holder in the horizontal direction and taking the pressure of the high-pressure gas holder in the vertical direction. Where HH
Indicates the upper limit set value (gas holder withstand pressure upper limit), PH indicates the upper limit set value, and PL indicates the lower limit set value. In the table, specific numerical examples thereof are also described in units of MPa.

When the current high-pressure gas holder pressure (PV) is equal to or higher than PH, that is, equal to or higher than 2.16 MPa, the flow control valve is always opened, and the radiation is recovered unconditionally to the low-pressure gas holder. However, although not shown in the table, if both the high-pressure gas holder pressure current value (PV) and low-pressure gas holder pressure current value (PV) are HH or more, that is, 2.35 MPa or more, atmospheric emission is performed. Will be Although not directly related to the present invention, the present high pressure gas holder pressure (PV) is
In the case of less than HH (less than 2.35 MPa) even if it is PH or more,
Dissipation is performed slowly, and when the high-pressure gas holder pressure current value (PV) is higher than HH, the radiation is performed at once so that the pressure does not rise any more.

Next, the current value of the high pressure gas holder pressure (PV) is
If the pressure is less than PH and not less than PL, the magnitudes of the low pressure gas holder pressure and the high pressure gas holder pressure are compared. If (low pressure gas holder pressure)> (high pressure gas holder pressure), the flow control valve is opened and the low pressure gas holder is moved from the high pressure gas holder to the low pressure gas holder. Supply gas to both gas-using facilities. Although not shown in the table, the flow regulating valve is also opened when the low-pressure gas holder pressure is higher than HH. On the other hand, when (low-pressure gas holder pressure) ≦ (high-pressure gas holder pressure), the flow control valve is closed, and gas is supplied from the low-pressure gas holder only to the equipment using low-pressure gas. However, when the low-pressure gas holder pressure is less than PL, that is, less than 0.69 MPa, the flow control valve is opened, and oxygen gas is introduced into the low-pressure gas holder and stored as an emergency backup.

When the high-pressure gas holder pressure current value (PV) is less than PL, compressed oxygen is supplied from the oxygen compressor, and the low-pressure gas holder pressure and the high-pressure gas holder pressure are compared, and (low-pressure gas holder pressure)> (High pressure gas holder pressure)
In this case, the flow control valve is opened to supply the gas from the low-pressure gas holder to both the high-pressure gas holder and the low-pressure gas using equipment. Although not shown in the table, the flow regulating valve is also opened when the low-pressure gas holder pressure is higher than HH. On the other hand, when (low-pressure gas holder pressure) ≦ (high-pressure gas holder pressure), the flow control valve is closed, and gas is supplied from the low-pressure gas holder only to the equipment using low-pressure gas. However, the low pressure gas holder pressure is less than PL, that is, 0.
If the pressure is lower than 69 MPa, the flow control valve is opened, and oxygen gas is introduced into the low-pressure gas holder and stored as an emergency backup.

That is, in the gas supply method of the present invention, when the pressure of the low-pressure gas holder is less than the lower limit set value, the gas flow control valve is opened to fill the low-pressure gas holder with the gas, and the pressure of the low-pressure gas holder is reduced. Low pressure gas holder pressure)
When the relationship between the pressure of the high-pressure gas holder and the pressure of the high-pressure gas holder (high-pressure gas holder pressure) is (low-pressure gas holder pressure)> (high-pressure gas holder pressure) and the pressure of the low-pressure gas holder is equal to or higher than the lower limit set value, the flow control valve is opened. The gas in the low-pressure gas holder is also supplied to the high-pressure gas holder, and the gas is supplied to both the high-pressure gas holder and the equipment using the low-pressure gas, (low-pressure gas holder pressure) ≦ (high-pressure gas holder pressure), and
When the low-pressure gas holder pressure is equal to or higher than the lower limit set value, the flow control valve is closed, and the gas is supplied only to the equipment using the low-pressure gas.

[0023]

EXAMPLE The gas supply method of the present invention was applied to an oxygen supply line in an integrated steelworks shown in FIG. Although not shown in the figure, a check valve is provided near the outlet of the oxygen compressor. That is, when the pressure of the low pressure gas holder is less than the lower limit set value, the gas flow control valve is opened to fill the gas, and the pressure of the low pressure gas holder (low pressure gas holder pressure) and the pressure of the high pressure gas holder (high pressure gas holder pressure) are reduced. The relationship is (low pressure gas holder pressure)> (high pressure gas holder pressure)
And, when the low-pressure gas holder pressure is equal to or higher than the lower limit set value, the flow control valve is opened, so that the gas in the low-pressure gas holder is also supplied to the high-pressure gas holder, and both the high-pressure gas using equipment and the low-pressure gas using equipment are used. When the gas is supplied to (low pressure gas holder pressure) ≦ (high pressure gas holder pressure) and the low pressure gas holder pressure is equal to or higher than the lower limit set value,
The flow control valve was closed, and gas was supplied only to equipment using low-pressure gas.

FIG. 2 shows a trend example of the high-pressure gas holder pressure and the low-pressure gas holder pressure at that time. FIG. 2 corresponds to FIG. 4 already described as a conventional gas supply method. As is apparent from FIG. 2, according to the present invention,
It can be seen that the problem that the low-pressure gas holder pressure, which has conventionally been a problem, becomes higher than the high-pressure gas holder pressure has been almost eliminated.

Next, based on FIG. 3, some specific examples of supply states in the oxygen gas supply line will be described to explain how the oxygen gas is supplied. FIG.
FIG. 3 is a schematic diagram illustrating an oxygen gas supply state at each time point indicated by arrows a, b, and c in the trend illustrated in FIG. These a, b, and c are (a), (b),
(C).

During the peak blowing shown in FIG. 3A, the flow control valve 8 is opened, and the oxygen gas shortage in the high pressure gas use equipment (converter, smelting reduction furnace, decarburization furnace) 13 is reduced by a low pressure gas holder. 9
To pay out from. After the peak blowing in FIG. 3B, the flow control valve 8 is closed, and oxygen gas is supplied only to the high-pressure gas holder 7.

In the period of blowing shown in FIG. 3C, when the pressure of the high-pressure gas holder 7 reaches the upper limit, the flow rate control valve 8 is opened, and the low-pressure gas holder 9 is allowed to diffuse and collect oxygen gas. I do. On the other hand, a conventional gas supply method is as described with reference to FIG. 4 as a conventional technique.

In the example of the present invention, the rate of oxygen gas emission to the atmosphere was reduced by about 2.5% as compared with the conventional example. As a result, in the example of the present invention, the power consumption of the oxygen plant was reduced by about 795 kWh / hr from the conventional example. In addition, although the example which connected only the high pressure gas using equipment to the high pressure gas holder was shown, the low pressure gas using equipment may also be connected.

Further, the low-pressure gas holder may be connected to a plurality of facilities using low-pressure gas.

[0030]

According to the present invention, the gas balance on the high pressure side which has been tight in the past during peak use can be alleviated, and the low pressure gas holder pressure can be reduced to near the lower limit. As a result, the ability of the low-pressure gas holder can be fully exhibited,
Operation with a wider range of pressure operation is possible, and unnecessary gas emission to the atmosphere can be significantly reduced, and as a result,
The power consumption of the oxygen plant can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a gas supply line suitable for applying the present invention.

FIG. 2 is a graph showing changes in the holder pressure of a high-pressure gas holder and a low-pressure gas holder when the present invention is applied.

FIG. 3 is a schematic diagram for explaining a gas flow in a gas supply line in each state when the present invention is applied.

FIG. 4 is a graph showing changes in the respective holder pressures of a conventional high-pressure gas holder and a low-pressure gas holder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air compressor 2 Rinsing cooling tower 3 Molecular sieves adsorber 4 Cold box (rectification tower, main heat exchanger, etc.) 5 Oxygen compressor 6 Oxygen dissipating valve 7 High pressure gas holder 8 Flow control valve 9 Low pressure gas holder 10a, 10b Pressure Total 11 Sequence controller 12 Blast furnace (Low pressure gas equipment) 13 Converter (High pressure gas equipment)

Claims (1)

[Claims] The pressurized gas is supplied to a high-pressure gas-using facility via a high-pressure gas holder, and is supplied to a low-pressure gas-using facility via a low-pressure gas holder having a flow control valve for adjusting a gas flow rate on a gas inlet side. In the gas supply method, the relationship between the pressure of the low-pressure gas holder and the pressure of the high-pressure gas holder is (low-pressure gas holder pressure)> (high-pressure gas holder pressure), and the low-pressure gas holder pressure is a lower limit set value. When the above is the case, the flow control valve is opened, the gas in the low-pressure gas holder is also supplied to the high-pressure gas holder, and (pressure of the low-pressure gas holder) ≦ (pressure of the high-pressure gas holder), and the pressure of the low-pressure gas holder is When the gas flow rate is equal to or higher than the lower limit value, the flow rate control valve is closed so that the gas in the low-pressure gas holder is supplied only to the low-pressure gas use facility. Supply method.