JPH08136073A - Method and apparatus for operation control of turbine type expander - Google Patents

Abstract

PURPOSE: To effectively prevent the overload operation of a turbine type expander disposed in two stage series. CONSTITUTION: First and second turbine inlet valves 15, 16 are respectively provided at the inlet sides of first and second turbines 11 and 12. A pressure regulator 20 detected the inlet pressure of the first turbine, and so regulates the opening of the valve 15 as to suppress the pressure to a predetermined pressure limit value or less. A number-of-revolutions regulator 21 detects the number of the revolutions of the first turbine to set the opening for suppressing the number of the revolutions to a predetermined number-of-revolutions limit value or less. A number-of-revolutions regulator 22 detects the number of the revolutions of the second turbine and sets the opening for suppressing the number of the revolutions to a predetermined number-of-revolutions limit value or less. An opening comparator 24 regulates the opening of the valve 16 based on the smaller one of both the set openings.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method and apparatus for controlling the operation of a two-stage turbine expander connected in series.

[0002]

2. Description of the Related Art In many cryogenic freeze liquefaction devices such as helium refrigerators, two stages of turbine type expanders are arranged in series in a refrigerant circulation passage for generating cold. By starting these turbine type expanders,
The liquefaction refrigerating apparatus is gradually cooled from room temperature to the temperature at the design point, but it is preferable to shorten the startup time until reaching the design point as much as possible. This start-up time becomes shorter as the amount Q of cold generated by the turbine expander increases, and this amount Q of cold is generally expressed by the following equation.

[0003]

[Expression 1] Q = K1 · Pi · √Ti · f (π) where K1 is a constant, Pi is the turbine inlet pressure, Ti is the inlet temperature, π is the pressure ratio (= Pi / Pe), and Pe is the turbine outlet. The pressure, f (π), is a function that increases with π. As is clear from this formula 1, the turbine inlet pressure Pi can be rapidly increased in order to rapidly increase the cold quantity Q. However, when the turbine inlet pressure Pi is excessively increased, the turbine pressure ratio Pi / Pe is increased and the rotational speed of the turbine type expander is abnormally increased (hereinafter referred to as overspeed), resulting in seizure. May cause troubles such as

Therefore, the following methods have been proposed as a method of rapidly proceeding the operation (particularly, the precooling operation) while preventing such an over-rotation of the turbine type expander.

A) Japanese Patent Publication No. 3-17062: A limit value of the downstream turbine inlet pressure corresponding to the inlet temperature of the upstream turbine type expander is set in advance, and the low temperature side turbine expander reaches this limit value. The operation of increasing the inlet pressure of the turbine by a pressure control valve (hereinafter referred to as the turbine inlet valve) and the operation of maintaining the pressure state until the inlet temperature of the turbine expander reaches the equilibrium terminal inlet temperature after this operation. Alternately (see Figure 5). According to this method, by controlling the inlet pressure of the low temperature side turbine expander by controlling the turbine inlet valve, it is possible to prevent the low temperature side turbine expander from rotating at an excessive speed while precooling the liquefying refrigeration system. it can.

B) JP-A-62-80455: A pressure control valve (hereinafter referred to as a turbine inlet valve) on the inlet side of the upstream turbine type expander and a downstream side of the outlet side of the downstream turbine type expander. Side pressure control valves (hereinafter referred to as turbine outlet valves) are provided, and the inlet pressure of the upstream turbine expander is kept below a predetermined pressure limit value by adjusting the opening of the turbine inlet valve. The outlet pressure of the downstream turbine expander is kept below the pressure limit value by adjusting the opening degree.

[0007]

As described above, in the apparatus in which the turbine type expanders are provided in two stages in series, the flow rate G1 of the upstream turbine type expander and Flow rate G of the downstream turbine expander
2 is represented by the following equation.

[0008]

[Equation 2]

Where K1 and K2 are constant coefficients, P1 is the inlet pressure of the upstream turbine expander, P2 is the outlet pressure of the upstream turbine expander, P3 is the inlet pressure of the downstream turbine expander, T1 is the inlet temperature of the upstream turbine expander, and T3 is the inlet temperature of the downstream turbine expander.

When both turbine type expanders are arranged in series,
Since G1 = G2, the following equation is obtained from the above mathematical expression 1.

[0011]

(Equation 3)

In the methods A) and B), since the outlet of the upstream turbine expander and the inlet of the downstream turbine expander are directly connected without a valve, P
2 = P3. Substituting this into Equation 2 gives the following equation.

[0013]

[Equation 4]

Therefore, theoretically, in the methods A) and B), the temperature ratio T1 / T3 is a function f (P1 / P2) of the pressure ratio P1 / P2 of the upstream turbine expander.
In other words, the pressure ratio P1 / P2 is equal to the temperature ratio T1 / T3.
Theoretically, the temperature ratio T1 /
Unless T3 changes, the pressure ratio P1 / P2 does not change even if the turbine inlet valve or the turbine outlet valve is operated. In actual operation, the pressure ratio P1 / P2 also fluctuates somewhat with changes in the opening of the turbine inlet valve, but its responsiveness is low, and even if the turbine inlet valve is throttled, the pressure ratio P1 / P2 immediately changes.
There is no guarantee that 2 will fall. Therefore, in the above methods A) and B), even if the turbine inlet valve or the turbine outlet valve is operated, the rotational speed of the turbine type expander, especially the rotational speed of the upstream turbine type expander can be adjusted as desired. No
There is a possibility that the turbine type expander may be over-rotated.

Further, in the method A), since the inlet pressure of the downstream turbine expander is increased stepwise, the performance of the turbine expander during precooling cannot be fully exerted. There is also the disadvantage that the pre-cooling time becomes longer accordingly.

In view of such circumstances, the present invention surely prevents overload operation of the two-stage turbine type expanders arranged in series, and more preferably, turbine type expansion which can also perform rapid precooling. An object of the present invention is to provide a machine operation control method and apparatus.

[0017]

SUMMARY OF THE INVENTION The present invention is a method for controlling the operation of a two-stage cold-generating turbine expander arranged in series with a refrigerant circulation circuit for generating cold, in which an upstream turbine is used. The upstream turbine inlet valve is installed on the inlet side of the expander, and the downstream turbine inlet valve is installed on the inlet side of the downstream turbine expander. Adjust one parameter of the inlet pressure of the expander, the rotation speed of the upstream turbine expander, and the rotation speed of the downstream turbine expander to meet a predetermined condition, and open the downstream turbine inlet valve. By adjusting, the remaining parameters are adjusted to meet predetermined conditions (claim 1).

More specifically, the inlet pressure of one of the turbine type expanders is detected, and the opening degree of the upstream turbine inlet valve is adjusted so as to keep this pressure below a preset pressure limit value. In addition, the opening of the downstream turbine inlet valve is set to detect the rotational speed of the upstream turbine expander and keep this rotational speed below a preset rotational speed limit value, and the downstream turbine Sets the opening of the downstream turbine inlet valve for detecting the rotation speed of the expansion machine and suppressing this rotation speed to a preset rotation speed limit value or less,
A method of adjusting the opening of the downstream turbine inlet valve based on the opening on the smaller side of the two openings (Claim 2), or detecting the inlet pressure of the upstream turbine expander to determine this pressure. While adjusting the opening degree of the upstream turbine inlet valve so as to be suppressed below a preset pressure limit value,
Set the opening of the downstream turbine inlet valve to detect the outlet pressure of the upstream turbine expander and keep this pressure above a preset pressure limit value, and the inlet of the downstream turbine expander The opening of the downstream turbine inlet valve for detecting the pressure and suppressing this pressure to a preset pressure limit value or less is set, and the downstream turbine is set based on the smaller opening of the two openings. A method of adjusting the opening degree of the inlet valve (claim 4) is preferable.

According to a second aspect of the present invention, the rotational speed limit value of the upstream turbine expander is changed according to the inlet temperature of the upstream turbine expander, and the rotational speed restriction value of the downstream turbine expander is changed. More preferably, the value is changed according to the inlet temperature of the downstream turbine expander (claim 3), and in the method according to claim 4, the pressure limit value of the outlet pressure of the upstream turbine expander is set. More preferably, it is changed according to the inlet temperature of the upstream turbine expander, and the pressure limit value of the inlet pressure of the downstream turbine expander is changed according to the inlet temperature of the downstream turbine expander ( Claim 5).

Further, in each of the above methods, the pressure limit value used for adjusting the opening degree of the upstream turbine inlet valve is changed according to the inlet temperature of the turbine type expander on the side relating to this pressure limit value. Such a superior effect can be obtained (Claim 6).

Further, the present invention relates to an operation control device for a two-stage cold-generating turbine expander arranged in series with a refrigerant circulation circuit for generating cold, the inlet of an upstream turbine expander. Side upstream side turbine inlet valve, the downstream side turbine type expander inlet side is provided with a downstream side turbine inlet valve, the inlet pressure of either one of the turbine type expander is detected and this pressure is preset. The upstream inlet valve adjusting means for adjusting the opening degree of the upstream turbine inlet valve so as to keep it below the pressure limit value, and the rotational speed of the upstream turbine expander is detected to set this rotational speed at a preset rotational speed. Upstream opening degree setting means for setting the opening degree of the downstream side turbine inlet valve to keep the number of revolutions below the number limit value, and detecting the number of rotations of the downstream side turbine expander and setting this number of rotations in advance Below the limit Downstream opening degree setting means for setting the opening degree of the downstream turbine inlet valve for suppressing, and the actual opening degree of the downstream turbine inlet valve for the opening degree set by the upstream opening degree setting means and the downstream opening degree. The downstream side inlet valve adjusting means for adjusting based on the opening degree on the smaller side of the opening degrees set by the degree setting means (claim 7).

In this apparatus, the upstream side opening degree setting means is configured to change the rotational speed limit value of the upstream side turbine type expander according to the inlet temperature of the upstream side turbine type expander, and the downstream side More preferably, the downstream side opening degree setting means is configured to change the rotational speed limit value of the turbine type expander according to the inlet temperature of the downstream side turbine type expander (claim 8).

Further, the present invention is an operation control device for a two-stage cold-generating turbine expander arranged in series in a refrigerant circulation circuit for generating cold, the inlet of an upstream turbine expander. Side upstream side turbine inlet valve, downstream side turbine type expander inlet side downstream side turbine inlet valve, upstream side turbine type expander inlet pressure is detected and this pressure is preset Upstream inlet valve adjusting means for adjusting the opening degree of the upstream turbine inlet valve so as to keep it below the limit value, and the outlet pressure of the upstream turbine expander is detected to set this pressure above a preset pressure limit value. Upstream opening degree setting means for setting the opening degree of the downstream turbine inlet valve to keep the pressure at the lower limit, and to detect the inlet pressure of the downstream turbine expander and keep this pressure below a preset pressure limit value. Under The downstream opening degree setting means for setting the opening degree of the side turbine inlet valve, and the actual opening degree of the downstream turbine inlet valve by the opening degree set by the upstream side opening degree setting means and the downstream side opening degree setting means. Downstream inlet valve adjusting means for adjusting based on the opening on the smaller side of the set opening is provided (claim 9).

In this apparatus, the upstream side opening degree setting means is configured to change the pressure limit value of the outlet pressure of the upstream side turbine type expander according to the inlet temperature of the upstream side turbine type expander. More preferably, the downstream opening degree setting means is configured to change the pressure limit value of the inlet pressure of the downstream turbine expander according to the inlet temperature of the downstream turbine expander (claim 10). .

Further, in each of the above devices, the upstream inlet valve is configured so that the pressure limit value used by the upstream inlet valve adjusting means is changed according to the inlet temperature of the turbine type expander on the side related to the pressure limit value. By configuring the adjusting means, a more excellent effect as described below can be obtained (claim 11).

[0026]

In the method according to the first aspect, the outlet pressure of the upstream turbine expander and the downstream turbine expander of the upstream turbine expander are controlled by operating the downstream turbine inlet valve provided on the inlet side of the downstream turbine expander. The inlet pressure can be different,
The pressure ratio of the upstream turbine expander can be freely adjusted without being restricted by the ratio between the inlet temperature of the upstream turbine expander and the inlet temperature of the downstream turbine expander. Therefore, depending on the change in the opening degree of the upstream turbine inlet valve, one of the parameters of the inlet pressure of either one of the turbine type expander, the rotational speed of the upstream turbine type expander, and the rotational speed of the downstream turbine type expander Is appropriately adjusted, and the remaining parameters are appropriately adjusted by adjusting the opening degree of the downstream side turbine inlet valve, whereby it is possible to prevent both turbine type expanders from over-rotating.

More specifically, in the method and apparatus according to claims 2 and 7, the inlet pressure of either one of the turbine type expanders is adjusted by changing the opening degree of the upstream turbine inlet valve, and the upstream side is adjusted. Set the opening of the downstream turbine inlet valve to detect the rotational speed of the turbine expander and keep this rotational speed below the preset rotational speed limit value, and rotate the downstream turbine expander. Number, and sets the opening of the downstream turbine inlet valve to keep this number of revolutions below a preset rotational speed limit value. By adjusting the opening degree of the side turbine inlet valve, the rotational speeds of both turbine expanders can be directly adjusted, and over-rotation can be reliably prevented.

Here, in the method and apparatus according to claims 3 and 8, the rotational speed limit value of the upstream turbine expander is changed according to the inlet temperature of the upstream turbine expander, and the downstream turbine is changed. By changing the rotational speed limit value of the rotary expander according to the inlet temperature of the downstream turbine expander, the rotational speed control of the turbine expander suitable for the operating temperature can be executed over a wide temperature range. Further, as compared with the conventional one in which the turbine pressure limit value is changed stepwise with a change in turbine temperature, the performance of each turbine expander can be more effectively exhibited during precooling.
The precooling time is reduced accordingly.

On the other hand, in the method and apparatus according to claims 4 and 9, the inlet pressure of the upstream turbine expander is adjusted by changing the opening degree of the upstream turbine inlet valve, and the upstream turbine expander is controlled. This is done by detecting the outlet pressure and setting the opening of the downstream turbine inlet valve to keep this pressure below a preset rotational speed limit value and by detecting the inlet pressure of the downstream turbine expander. Set the opening of the downstream turbine inlet valve to keep the pressure below the preset rotational speed limit value, and based on the smaller opening of both openings, the actual opening of the downstream turbine inlet valve. By adjusting, the rotational speeds of both turbine type expanders can be indirectly controlled without directly detecting the rotational speeds of both turbine type expanders, and over-rotation can be prevented.

Here, in the method and apparatus according to claims 5 and 10, the pressure limit value of the outlet pressure of the upstream turbine expander is changed according to the inlet temperature of the upstream turbine expander, and the downstream side is changed. By changing the pressure limit value of the inlet pressure of the side turbine expander according to the inlet temperature of the downstream turbine expander, it is possible to control the pressure of the turbine expander suitable for the operating temperature over a wide temperature range. I can do it.
Further, as compared with the conventional one in which the turbine pressure limit value is changed stepwise with a change in turbine temperature, the performance of each turbine expander can be more effectively exhibited during precooling. Minute pre-cooling time is shortened.

Further, in the method and the apparatus according to claims 6 and 11, the pressure limit value used for adjusting the opening degree of the upstream side turbine inlet valve is set according to the inlet temperature of the turbine type expander on the side relating to this pressure limit value. By changing it, the inlet pressure control of the turbine expander suitable for the operating temperature can be executed over a wide temperature range.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a helium liquefaction refrigerating apparatus in which the method of the present invention is carried out. In the figure, 1 is a liquid helium dewar (container), 2 is a cool box, helium as a refrigerant is stored in the liquid helium dewar 1, and five heat exchangers are placed in the cool box 2 in order from the low temperature side. 5,
6, 7, 8, 9 are installed.

A compressor 10 is provided outside the cool box 2, and the discharge side of the compressor 10 has heat exchangers 9, 8, 7,
A low pressure return which is connected to the inside of the liquid helium dewar 1 through a high pressure supply line 3 which passes through 6, 5 in this order and which also passes through the heat exchangers 5, 6, 7, 8, 9 in this order. It is connected to the suction side of the compressor 10 via a line 4. A JT valve 14 is provided at a position on the outlet side of the heat exchanger 5 in the high pressure supply line 3.

The turbine-type expander operation control method of the present invention is not limited to the liquefaction refrigeration system in which both lines 3 and 4 are connected to the liquid helium dewar 1, and both lines 3 and 4 are connected only to the refrigeration load. It can also be applied to refrigeration equipment.

A portion of the high pressure supply line 3 located between the heat exchangers 8 and 9 and a low pressure return line 4
In, the location located between the heat exchangers 5 and 6 is
It is connected via a turbine line 13. The turbine line 13 passes through the heat exchanger 7, and an upstream turbine expander (hereinafter, simply referred to as “first turbine”) 11 is provided at a position upstream of the heat exchanger 7. A downstream turbine expander (hereinafter, simply referred to as “second turbine”) at a position downstream of the heat exchanger 7.
12 are provided. Therefore, both turbines 11, 12
Are arranged in series with the turbine line 13.

In this turbine line 13, a first turbine inlet valve (upstream turbine inlet valve) 15, a second turbine inlet valve (downstream turbine inlet valve) 16, thermometers 17, 1
8, pressure regulator (upstream inlet valve adjusting means) 20, rotation speed regulator (upstream opening setting means) 21, rotation speed regulator (downstream opening setting means) 22, and opening comparator (downstream) A side inlet valve adjusting means) 24 is provided.

The first turbine inlet valve 15 is provided on the inlet side of the first turbine 11, and the second turbine inlet valve 16 is the inlet side of the second turbine 12 and the outlet of the heat exchanger 7. It is provided on the side. The thermometer 17 is the first
The pressure regulator 2 detects the detection signal of the inlet temperature T1 of the turbine 11.
0 and the rotation speed adjuster 21, and the thermometer 18 outputs a detection signal of the inlet temperature T2 of the second turbine 12 to the rotation speed adjuster 22.

The pressure regulator 20 stores the pressure limit value of the first turbine inlet pressure P1 which is predetermined corresponding to the first turbine inlet temperature T1 and detects the actual first turbine inlet pressure P1. The opening of the first turbine inlet valve 15 is adjusted so that this pressure is kept below the pressure limit value. In this embodiment, as shown in FIG. 2A, in the region where the first turbine inlet temperature T1 exceeds the rated temperature To, the pressure limit value of the inlet pressure P1 increases as the first turbine inlet temperature T1 decreases. In the region where the first turbine inlet temperature T1 is equal to or lower than the rated temperature To, the pressure limit value is set to the rated pressure P1o.

The rotation speed adjuster 21 includes a first turbine 11 which is predetermined in correspondence with the first turbine inlet temperature T1.
The first rotation speed limit value of the rotation speed (revolutions per unit time) is stored, the actual first turbine rotation speed N1 is detected, and the first rotation speed N1 is controlled to be equal to or lower than the rotation speed limit value. The opening of the turbine inlet valve 15 is set, and the setting signal is output to the opening comparator 24. In this embodiment, as shown in FIG. 2 (b), in the region where the first turbine inlet temperature T1 exceeds the rated temperature To, the rotational speed limit value of the rotational speed N1 increases as the first turbine inlet temperature T1 decreases. In the region where the second turbine inlet temperature T1 is increased and is equal to or lower than the rated temperature To, the rotation speed limit value is set to the rated rotation speed N1o.

Similarly, the rotation speed regulator 22 stores the rotation speed limit value of the rotation speed (rotation speed per unit time) of the second turbine 12 which is predetermined corresponding to the second turbine inlet temperature T2. In addition, the actual second turbine rotation speed N2 is detected, and the opening degree of the second turbine inlet valve 16 for suppressing this rotation speed N2 to the rotation speed limit value or less is set, and the setting signal is compared with the opening degree. It is output to the container 24. In this embodiment, as shown in FIG. 2C, in the region where the second turbine inlet temperature T3 exceeds the rated temperature To,
As the second turbine inlet temperature T3 decreases, the rotational speed limit value of the rotational speed N2 is increased, and in the region where the second turbine inlet temperature T3 is equal to or lower than the rated temperature To, the rotational speed limit value is set to the rated rotational speed N2o. Has been done.

The opening comparator 24 is the rotation speed adjuster 21.
The opening degree set by the above is compared with the opening degree set by the rotation speed controller 22, the smaller one is selected, and the opening degree of the second turbine inlet valve 16 is adjusted based on this opening degree. is there.

Next, the operation of this device will be described.

The refrigerant (helium) discharged from the compressor 10 is cooled by liquid nitrogen in the heat exchanger 9 through the high-pressure supply line 3, and then introduced into the liquid helium dewar 1 through the JT valve 14, and this liquid Helium Dewar 1
The evaporated helium gas from 1 is returned to the suction side of the compressor 10 through the low pressure return line 4.

A part of the helium cooled by the heat exchanger 9 is divided into the turbine line 13 and the low pressure return line 4
to go into. In the turbine line 13, the thermometer 17 detects the inlet temperature T1 of the first turbine 11, and the pressure limit value of the inlet pressure P1 of the first turbine 11 is determined based on the first turbine inlet temperature T1. The actual first turbine inlet pressure P1 is detected by the pressure regulator 20, and the opening of the first turbine inlet valve 15 is adjusted so as to keep the inlet pressure P1 below the pressure limit value. This suppression of the first turbine inlet pressure P1 indirectly causes the second pressure
The turbine inlet pressure P3 is also suppressed.

On the other hand, in the rotation speed adjuster 21, the rotation speed limit value of the rotation speed N1 of the first turbine 11 is determined based on the first turbine inlet temperature T1. The first turbine rotation speed N1 is detected, and an opening degree for setting this rotation speed N1 below the rotation speed limit value is set. Similarly, in the rotation speed adjuster 22, the rotation speed limit value of the rotation speed N2 of the second turbine 12 is determined based on the second turbine inlet temperature T3 detected by the thermometer 18, while this rotation speed adjuster is used. The actual second turbine rotation speed N2 is detected by 22 and an opening degree for setting this rotation speed N2 below the rotation speed limit value is set. Then, the opening degree of the second turbine inlet valve 16 is adjusted by the opening degree comparator 24 based on the smaller one of the set opening degrees, whereby the over-rotation of both turbines 11 and 12 can be surely prevented. Be done.

In addition, in this embodiment, the first turbine inlet pressure P1 and the limiting values of both turbine rotational speeds N1 and N2 are determined according to the inlet temperatures T1 and T2 of the turbines 11 and 12, so that a wide temperature range can be obtained. Appropriate inlet pressure control and rotational speed control can be executed over the range. Further, as compared with the conventional case where the pressure limit value is increased stepwise according to the temperature drop, the performance of both turbines 11 and 12 can be more effectively exerted during the precooling. Pre-cooling time can be shortened.

Next, a second embodiment will be described. In this embodiment, pressure regulators 25 and 26 are provided instead of the rotation speed regulators 21 and 22 in the first embodiment.

The pressure regulator 25 stores the pressure limit value of the outlet pressure P2 of the first turbine 11 which is predetermined corresponding to the first turbine inlet temperature T1 and also stores the actual first turbine outlet pressure P2. Detected, this outlet pressure P2
The opening degree of the second turbine inlet valve 16 for maintaining the above-mentioned pressure limit value or more is set, and the setting signal is output to the opening degree comparator 24. In this embodiment, as shown in FIG. 4A, in a region where the first turbine inlet temperature T1 exceeds the rated temperature To, the pressure limit value of the outlet pressure P2 increases as the first turbine inlet temperature T1 decreases. In the region where the second turbine inlet temperature T3 is equal to or lower than the rated temperature To, the pressure limit value is set to the rated pressure P2o.

Similarly, the pressure adjuster 26 stores the pressure limit value of the inlet pressure P3 of the second turbine 12 which is predetermined corresponding to the second turbine inlet temperature T2, and also the actual second turbine inlet. The pressure P3 is detected, the opening degree of the second turbine inlet valve 16 for suppressing the inlet pressure P3 to the pressure limit value or less is set, and the setting signal is output to the opening degree comparator 24. In this embodiment, as shown in FIG. 4B, in the region where the second turbine inlet temperature T3 exceeds the rated temperature To, the second turbine inlet temperature T
The pressure limit value of the inlet pressure P3 is increased as 3 falls, and the pressure limit value is set to the rated pressure P3o in the region where the second turbine inlet temperature T3 is equal to or lower than the rated temperature To.

The opening degree comparator 24 compares the opening degree set by the pressure regulator 25 with the opening degree set by the pressure regulator 26, and selects the smaller one to select the opening degree. Based on the above, the opening degree of the second turbine inlet valve 16 is adjusted.

According to this embodiment, like the first embodiment,
By adjusting the opening of the first turbine inlet valve 15, the first turbine 11
Inlet pressure P1 of the first turbine 11 is controlled to be equal to or lower than the limit value, while the opening pressure of the second turbine inlet valve 16 is adjusted to keep the outlet pressure P2 of the first turbine 11 equal to or higher than the pressure limit value.
The inlet pressure P3 can be suppressed below the pressure limit value. Here, since the rotational speeds of the turbines 11 and 12 are greatly influenced by the respective turbine pressure ratios P1 / P2 and P3 / P4 (P4 is the second turbine outlet pressure), the outlet pressure P2 and the inlet pressure P3 are By adjusting, without using a relatively expensive turbine tachometer or speed regulator,
The relatively inexpensive pressure regulators 25 and 26 can be used to indirectly prevent over-rotation of both turbines 11 and 12.

Also in this embodiment, each pressure P1, P
2, the inlet temperature T of each turbine 11 and 12 is set to the limit value of P3.
Since it is determined according to T1 and T2, appropriate inlet pressure control and rotational speed control can be executed over a wide temperature range.

The present invention is not limited to the above embodiments, but the following modes can be adopted as examples.

(1) In each of the above-mentioned embodiments, control of both turbine rotational speeds N1, N2 (first embodiment), pressures P2, P
If the opening degree of the second turbine inlet valve 16 is made too small or fully closed to perform the control of No. 3, the outlet pressure P2 of the first turbine 11 excessively rises due to the blockage of the turbine line 13. Since the first turbine 11 may be damaged or the second turbine inlet valve 16 may be opened again, the rotational speeds N1 and N2 of the turbines 11 and 12 may suddenly increase and become uncontrollable. The opening lower limit value is set in the comparator 24, and the rotation speed adjuster 2
The opening comparator 24 is configured so that the opening of the second turbine inlet valve 16 is maintained at the opening lower limit value or more regardless of the setting signals of the pressure adjusting devices 1 and 22 and the pressure adjusters 25 and 26. , And more preferable. Further, it is more preferable if the opening comparator 24 is configured to issue a warning command when the set opening becomes less than or equal to the opening lower limit value.

(2) In the first embodiment, the inlet pressure P3 of the second turbine 12 may be adjusted by operating the first turbine inlet valve 15. If this inlet pressure P3 is lowered, the first turbine inlet pressure P1 can be consequently lowered.

(3) In the device of the first embodiment, the first
The turbine inlet valve 15 is operated to adjust either the rotational speed N1 of the first turbine 11 or the rotational speed N2 of the second turbine 12, and the inlet pressure P1 of the first turbine 11 is operated by operating the second turbine inlet valve 16. Alternatively, it is also possible to adjust the inlet pressure P2) of the second turbine 12 and the other of the rotation speeds N1 and N2. In addition, in the device of the second embodiment, the operation of the first turbine inlet valve 15 causes the first turbine 11 to operate.
Of the outlet pressure P2 of the first turbine 11 and the inlet pressure P3 of the second turbine 12 are adjusted by operating the second turbine inlet valve 16.
It is also possible to regulate the other of P3.

[0058]

As described above, according to the present invention, the following effects can be obtained.

According to the method of claim 1, the upstream turbine inlet valve is provided on the inlet side of the upstream turbine expander, and the downstream turbine inlet valve is provided on the inlet side of the downstream turbine expander. By changing the opening degree of the inlet valve, while adjusting one parameter of the inlet pressure of either one of the turbine type expander, the rotational speed of the upstream turbine expander, the rotational speed of the downstream turbine expander, Since the remaining parameters are adjusted by adjusting the opening of the downstream turbine inlet valve, the outlet pressure of the upstream turbine expander and the downstream turbine expander can be adjusted by operating the downstream turbine inlet valve. By freely differentiating the inlet pressure of the two, it is possible to prevent over-rotation of both turbine type expanders.

More specifically, in the method and apparatus according to claims 2 and 7, the inlet pressure of one of the turbine type expanders is adjusted by changing the opening degree of the upstream turbine inlet valve, and the upstream side is adjusted. Set the opening of the downstream turbine inlet valve to detect the rotational speed of the turbine expander and keep this rotational speed below the preset rotational speed limit value, and rotate the downstream turbine expander. Number, and sets the opening of the downstream turbine inlet valve to keep this number of revolutions below a preset rotational speed limit value. Since the opening degree of the side turbine inlet valve is adjusted, the rotational speeds of both turbine type expanders can be directly adjusted, and there is an effect that over-rotation can be more reliably prevented.

Here, in the method and apparatus according to claims 3 and 8, the rotational speed limit value of the upstream turbine expander is changed according to the inlet temperature of the upstream turbine expander, and the downstream turbine is expanded. Effect of changing the rotational speed limit value of the rotary expander according to the inlet temperature of the downstream turbine expander, thereby enabling the rotational speed control of the turbine expander suitable for the operating temperature over a wide temperature range There is. In addition, compared to the conventional method in which the turbine pressure limit value is changed stepwise as the turbine temperature changes, the performance of each turbine expander can be more effectively exhibited during precooling. This has the effect of shortening the time.

On the other hand, in the method and apparatus according to claims 4 and 9, the inlet pressure of the upstream turbine expander is adjusted by changing the opening of the upstream turbine inlet valve, and the upstream turbine expander is also controlled. This is done by detecting the outlet pressure and setting the opening of the downstream turbine inlet valve to keep this pressure below a preset rotational speed limit value and by detecting the inlet pressure of the downstream turbine expander. Set the opening of the downstream turbine inlet valve to keep the pressure below the preset rotational speed limit value, and based on the smaller opening of both openings, the actual opening of the downstream turbine inlet valve. The turbine speed can be adjusted indirectly with an inexpensive structure without directly detecting the rotation speed of both turbine expanders using an expensive tachometer, etc. There is an effect that can prevent.

Here, in the method and apparatus according to claims 5 and 10, the pressure limit value of the outlet pressure of the upstream turbine type expander is changed according to the inlet temperature of the upstream turbine type expander, and the downstream side is changed. By changing the pressure limit value of the inlet pressure of the side turbine expander according to the inlet temperature of the downstream turbine expander, it is possible to control the pressure of the turbine expander suitable for the operating temperature over a wide temperature range. There is an effect that can be executed. In addition, compared to the conventional method in which the turbine pressure limit value is changed stepwise as the turbine temperature changes, the performance of each turbine expander can be more effectively exhibited during precooling. This has the effect of shortening the time.

Further, in the method and the apparatus according to claims 6 and 11, the pressure limit value used for adjusting the opening degree of the upstream turbine inlet valve is set according to the inlet temperature of the turbine type expander on the side relating to this pressure limit value. By changing it, the inlet pressure control of the turbine expander suitable for the operating temperature can be executed over a wide temperature range.

[Brief description of drawings]

FIG. 1 is a flow sheet showing the overall configuration of a helium liquefaction refrigerating apparatus in a first embodiment of the present invention.

FIG. 2A is a graph showing a relationship between a first turbine inlet temperature and a first turbine inlet pressure limit value set in the apparatus, and FIG. 2B is a first turbine inlet temperature set in the apparatus. And (c) is a graph showing the relationship between the second turbine inlet temperature and the second turbine speed limit value set in the above device.

FIG. 3 is a flow sheet showing the overall configuration of a helium liquefaction refrigeration system according to a second embodiment of the present invention.

FIG. 4A is a graph showing a relationship between a first turbine inlet temperature set in the above apparatus and a limit value of a first turbine outlet pressure, and FIG. 4B is a second turbine inlet temperature set in the above apparatus. 6 is a graph showing the relationship between the second turbine inlet pressure limit value and.

FIG. 5 is a graph showing the relationship between the upstream turbine-side expander inlet pressure limit value set by the conventional turbine-type expander operation control method and the downstream turbine-type expander inlet temperature.

[Explanation of symbols]

 3 High-pressure supply line 4 Low-pressure return line 11 1st turbine (upstream turbine expander) 12 2nd turbine (downstream turbine expander) 13 Turbine line 15 1st turbine inlet valve 16 2nd turbine inlet valve 17, 18 Thermometer 20 Pressure regulator (upstream inlet valve adjusting means) 21 Rotation speed regulator (upstream opening setting means) 22 Rotation speed regulator (downstream opening setting means) 24 Opening comparator (downstream inlet valve) Adjusting means) 25 Pressure adjuster (upstream opening degree setting means) 26 Pressure adjuster (downstream opening degree setting means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoichi Uetani 1-3-18 Wakihamacho, Chuo-ku, Kobe City Kobe Steel, Ltd. Kobe Head Office

Claims (11)

[Claims] 1. A method for controlling the operation of a two-stage cold-generation turbine expander arranged in series in a refrigerant circulation circuit for generating cold, the upstream side being upstream of the inlet side of the upstream turbine expander. Side turbine inlet valve is installed, the downstream turbine inlet valve is installed on the inlet side of the downstream turbine expander, and the inlet pressure of either one of the turbine type expander is changed depending on the opening degree of the upstream turbine inlet valve. One of the rotational speed of the turbine expander and the rotational speed of the downstream turbine expander is adjusted to meet a predetermined condition, and the remaining parameters are adjusted to a predetermined condition by adjusting the opening of the downstream turbine inlet valve. A method for controlling the operation of a turbine type expander, which is characterized in that it is adjusted to meet 2. The operation control method for a turbine expander according to claim 1, wherein the inlet pressure of any one of the turbine expanders is detected and the pressure is controlled to be equal to or lower than a preset pressure limit value. While adjusting the opening degree of the upstream turbine inlet valve, the downstream turbine inlet valve for detecting the rotational speed of the upstream turbine expander and keeping this rotational speed below a preset rotational speed limit value. The opening degree is set, and the rotation rate of the downstream side turbine expander is detected, and the opening degree of the downstream side turbine inlet valve for suppressing this rotation rate to a preset rotation speed limit value or less is set, A method for controlling operation of a turbine type expander, characterized in that the opening degree of the downstream turbine inlet valve is adjusted based on the smaller opening degree of the two opening degrees. 3. The operation control method for a turbine expander according to claim 2, wherein the rotational speed limit value of the upstream turbine expander is changed according to the inlet temperature of the upstream turbine expander, A method for controlling the operation of a turbine type expander, wherein the rotational speed limit value of the side turbine type expander is changed according to the inlet temperature of the downstream side turbine type expander. 4. The turbine expander operation control method according to claim 1, wherein the inlet pressure of the upstream turbine expander is detected, and the upstream pressure is controlled to be equal to or lower than a preset pressure limit value. Adjusts the opening of the turbine inlet valve on the side and detects the outlet pressure of the upstream turbine expander and sets the opening of the turbine inlet valve on the downstream side to maintain this pressure above a preset pressure limit value. In addition, the opening of the downstream turbine inlet valve for detecting the inlet pressure of the downstream turbine expander and suppressing this pressure below a preset pressure limit value is set. A method for controlling the operation of a turbine type expander, characterized in that the opening of the downstream turbine inlet valve is adjusted based on the opening on the smaller side. 5. The operation control method for a turbine expander according to claim 4, wherein the pressure limit value of the outlet pressure of the upstream turbine expander is changed according to the inlet temperature of the upstream turbine expander, A method for controlling the operation of a turbine type expander, characterized in that the pressure limit value of the inlet pressure of the downstream side turbine type expander is changed according to the inlet temperature of the downstream side turbine type expander. 6. The method of controlling the operation of a turbine expander according to claim 2, wherein a pressure limit value used for adjusting the opening degree of the upstream turbine inlet valve is a turbine on the side related to the pressure limit value. A method for controlling the operation of a turbine type expander, which is characterized in that it is changed according to the inlet temperature of the type expander. 7. An operation control device for a two-stage turbine expander for cold generation, which is arranged in series with a refrigerant circulation circuit for generating cold, the upstream side being upstream of an inlet side of the upstream turbine expander. Side turbine inlet valve is installed, the downstream turbine inlet valve is installed on the inlet side of the downstream turbine expander, and the inlet pressure of either one of the turbine expanders is detected to set this pressure to a preset pressure limit. The upstream inlet valve adjusting means for adjusting the opening degree of the upstream turbine inlet valve so as to keep it below the value, and the rotational speed of the upstream turbine expander is detected to detect this rotational speed. The upstream opening degree setting means for setting the opening degree of the downstream side turbine inlet valve to suppress the rotation speed below, and the rotation speed of the downstream side turbine expander are detected, and this rotation speed is set to a preset rotation speed limit value or less. To keep down Downstream opening degree setting means for setting the opening degree of the flow side turbine inlet valve, and the actual opening degree of the downstream turbine inlet valve set by the upstream side opening degree setting means and the downstream side opening degree setting means The operation control device for a turbine expander, comprising: a downstream-side inlet valve adjusting unit that adjusts the opening on the smaller side of the openings set by the above. 8. The operation control device for a turbine expander according to claim 7, wherein the rotational speed limit value of the upstream turbine expander is changed according to the inlet temperature of the upstream turbine expander. The upstream side opening degree setting means is configured, and the downstream side opening degree setting means is configured to change the rotational speed limit value of the downstream side turbine type expander according to the inlet temperature of the downstream side turbine type expander. An operation control device for a turbine type expander, which is characterized by: 9. An operation control device for a two-stage turbine expander for cold generation, which is arranged in series with a refrigerant circulation circuit for generating cold, and which is upstream of an inlet side of the upstream turbine expander. Side turbine inlet valve is installed, the downstream turbine inlet valve is installed on the inlet side of the downstream turbine expander, and the inlet pressure of the upstream turbine expander is detected and this pressure is set to a preset pressure limit value or less. Upstream inlet valve adjusting means for adjusting the degree of opening of the upstream turbine inlet valve so as to suppress the above, and to detect the outlet pressure of the upstream turbine expander and maintain this pressure above a preset pressure limit value. Upstream opening degree setting means for setting the opening degree of the downstream turbine inlet valve, and the downstream side for detecting the inlet pressure of the downstream turbine expander and suppressing this pressure below a preset pressure limit value. With turbine The downstream side opening degree setting means for setting the opening degree of the mouth valve, and the actual opening degree of the downstream side turbine inlet valve are set by the upstream side opening degree setting means and the downstream side opening degree setting means. The downstream side inlet valve adjusting means for adjusting the opening degree on the smaller side of the opening degrees. 10. The operation control device for a turbine expander according to claim 9, wherein the pressure limit value of the outlet pressure of the upstream turbine expander is changed according to the inlet temperature of the upstream turbine expander. The upstream side opening setting means, and the downstream side opening setting means for changing the pressure limit value of the inlet pressure of the downstream side turbine type expander according to the inlet temperature of the downstream side turbine type expander. An operation control device for a turbine type expander, which is characterized in that: 11. The operation control device for a turbine expander according to any one of claims 7 to 10, wherein the pressure limit value used by the upstream side inlet valve adjusting means is the turbine type expansion on the side related to this pressure limit value. An operation control device for a turbine type expander, characterized in that the upstream side inlet valve adjusting means is configured so as to be changed according to an inlet temperature of the machine.