JPS5963385A - Method of adjusting capacity of volume system two stage type compressor - Google Patents

Abstract

PURPOSE:To permit always the optimum intermediate stage running even in any variation of running condition by adjusting volumetrically a one-stage side compressor according to pressure feed required from varying program and two-stage side compressor to provide the optimum intermediate stage pressure respectively. CONSTITUTION:Whether or not handled gas discharged from a 2-stage side compressor 2 fills pressure feed capacity required from the process side is judged by a pressure regulator 10 so that the rotational frequency of a variable speed motor 5a is increased or decreased through a rotational frequency regulator 6a to adjust the capacity of a 1-stage side compressor (1) and fill the pressure feed capacity. Next, the rotational frequency of a variable speed motor 5b is increased or decreased through a rotational frequency regulator 6b by a power regulator 12 to minimize the value computed by an adder 11 adding power of the variable speed motors 5a, 5b for adjusting the capacity of the 2-stage side compressor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacity adjustment method suitable for processes with large fluctuations in conduit pressure or discharge pressure. The present invention relates to a capacity adjustment method for a two-stage compressor.

In recent years, as processes using multi-stage expansion compressors have become more complex, the operating range of the compressor has become wider. In such wide-ranging operation, the operating conditions change rapidly and the compressor drive power consumption is enormous. Therefore, there is a need for an operating method that consumes less power.

By the way, as is known, in multi-stage expansion compressors including two-stage compressors, an intermediate/cooling device is usually provided in order to reduce power.When performing intermediate cooling in such multi-stage compression, The minimum theoretical adiabatic power of (1↓[,,l's:
Suction pressure (Kg[10)j abs)1'd: Discharge pressure () ■S ” Jl included @ (1)l / 110ur)
Z: If the intermediate stage pressure of each stage is set according to the number of stages, theoretically the minimum adiabatic power will be obtained. However, in reality, the adiabatic efficiency of each membrane compressor is different, so the intermediate stage pressure at which the sum of the motive power of each membrane compressor is minimized is set in consideration of these adiabatic efficiencies.

As understood from the above formula ([), this intermediate stage pressure is
It changes if the suction pressure or discharge pressure changes. In other words, if the suction iΔ pressure and the discharge pressure change, there will be an optimal intermediate stage pressure at which the power is minimum.

However, when setting up a conventional multi-stage expansion compressor, given the design discharge pressure and design discharge pressure, the sum of the power of each membrane compressor is minimized, taking into account adiabatic efficiency. The design intermediate stage pressure is determined through repeated calculations, and the compressor is designed to achieve the designed intermediate stage pressure.In other words, the intermediate stage pressure is optimal only for one given suction pressure and discharge pressure. The stage pressure is -].

However, as mentioned above, in recent years there have been an increasing number of processes in which the suction pressure or discharge pressure is large (variable), and in processes with such large fluctuations, it is necessary to operate at the designed intermediate stage pressure. There are very few cases where this happens, and unnecessary power consumption is inevitable.

In view of the above-mentioned drawbacks, it is an object of the present invention to provide a capacity adjustment method that adjusts f so that even if there are fluctuations in suction pressure or discharge pressure, the intermediate stage pressure is always optimal. The feature is that the capacity of the first stage compressor is adjusted according to the required pumping capacity from the fluctuating process, and the power consumption of the compressor drive machine is reduced at the adjusted capacity. Minimum optimal intermediate stage 1
There is a point number to adjust the capacity of the 22nd stage side compression so that it becomes the upper blade.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

The figure shows a positive displacement two-stage compressor to which the capacity adjustment method according to the present invention is applied. while each compressor 1.2 is connected to a speed increaser 4a+4, respectively.
It is designed to be driven by variable speed motors 5a+5b via motors b.

The variable speed motors 5a + 5b have a total number of rotations 5a, 5b for adjusting these rotational speeds and a high-speed limiter for limiting the number of rotations within a preset control range. 7 a + 7 +) l Low speed limiter 8a.

81>, and wattmeters 9a and 9b are provided for detecting the power consumption of each variable speed motor 5a and 51).

Additionally, an IL force adjustment h110 is provided between the second-stage side IE compressor 2 and the subsequent process (not shown).
This makes it possible to determine whether the pumping capacity required by the process side is satisfied or not (L7), and to adjust the rotational speed of the variable speed motor 5a via the rotational speed controller 6a. On one day, the position where the pressure adjustment 5110 is provided is as follows:
It is needless to say that it is not limited thereto, and may be used on the suction side of the Shobara 1 machine, or may be replaced with an old style Er1j meter.

Furthermore, the adder 11 is connected to the wattmeter 93.9') and adds the electric power of the iiJ variable speed motors 5a and 5b, and the rotation speed controller 51) is adjusted so that the sum calculated by the adder 11i is the minimum. A power controller 12 is provided so as to be able to adjust the rotational speed of the PJ variable speed motor 51 via the PJ variable speed motor 51.

Note that a differential pressure switch 13 is provided between the suction side and the discharge side of the second-stage compressor 2 to detect the pressure difference between the two. +ThT on the nJ speed motor 5b side even if the constant value is exceeded.
h millimeter tough 1 is activated to suppress an increase in the rotational speed of the variable speed controller 5b.

In addition, 14a and 4b are temperature switches, and 15 is a safety valve f, both of which are provided to protect the compressor.

Next, a method for adjusting the capacity of the positive displacement two-stage compressor constructed as described above will be explained.

First, compressors 1 and 2 are operated.
Whether the handling waste discharged from the stage side compressor 2 satisfies the pumping capacity required from the process side (not shown) is determined by the pressure adjustment jηJ meter 10 by l', lJ, and the pumping capacity is satisfied. Rotation number word r! The capacity of the first-stage compressor is adjusted by increasing or decreasing the rotational speed of the variable speed motor 5a through a total of 11 and 6a.

1) The judgment of ij and the number of notes fr'o may be done by the creator (or (or they may be done automatically).

Then, the power controller FM meter 12 inputs i through the rotation speed controller 6b so that the speed calculated by the adder ill becomes the minimum value.
'i Adjust the capacity π of the second stage LL rice machine by increasing or decreasing the rotational speed of the J variable speed motor 5b. This adjustment may be performed by the worker K as described above, or may be automated.

Adjustment of the rotational speed of the IRJ variable speed motors 5a and 5b
Abnormal increase in rotation speed and abnormal decrease in speed at time i can be prevented by high-speed remixing 7a+7b+low-speed remixing 8a, 8b.

In addition, in the embodiment described in IJ, when the second stage side compressor changes to the IJ speed side by two forces, the rotation speed is limited by the high speed limiter 7a.
, 7b, and the safety protection of the compressor was also limited by the differential pressure switch 13, but instead of the differential pressure switch 13, the temperature switch 14bl is used.
In other words, restrictions may be imposed based on the temperature on the discharge side of the second-stage compressor 2.

Further, in the above embodiment, the capacity adjustment of the compressor 1.2 was carried out by so-called rotation speed control by changing the rotation speed of the variable speed motors 5a and 5b, but the invention is not limited to this. Any system may be used as long as it can reduce the power of the drive machine of the machine.In addition to the above, for example, in the case of a screw compressor with a slide screw
Capacity adjustment similar to that described above can be performed.

As is clear from the above explanation, according to the present invention, the capacity of the first-stage compressor is adjusted to meet the delivery capacity required by the compressed gas usage process, and the state in which this capacity adjustment is performed is achieved. , the second stage side compressor is connected to this
The capacity is adjusted so that the sum of the power consumption of the drive machines of the stage-side compression rock is minimized.

Therefore, the compressor is always operated at the optimum intermediate stage pressure regardless of any fluctuations in operating conditions, so that the power consumption of the compressor as a whole can be significantly reduced, and the following effects can also be obtained.

1) It can be operated at a lower discharge pressure than the intermediate stage pressure determined based on the design point. (In this case, the conventional technology cannot lower the final stage discharge pressure than the intermediate stage pressure.) However, according to the present invention, since the intermediate stage pressure can be changed arbitrarily, the discharge pressure can be operated lower than the designed intermediate stage pressure.) 2) The performance of the compressor main body changes and the intermediate stage pressure becomes lower than the designed value. Even if it changes, it can still be operated with minimal power.

3) Even if there are fluctuations that affect the discharge pressure or suction pressure, such as changes in the resistance of the narrow pipes and changes in the cooling water, it can always be operated at the minimum power.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a system diagram of a positive displacement two-stage compressor to which the method according to the present invention is applied. 1...1st stage side pressure compressor, 2...2nd stage side compressor,
sa + 5b...variable speed motor, 5a, 5b
... Rotation speed controller, 9a, 9b... Power meter,
lO...Pressure controller, 11...Adder,
12...Power controller.

Claims (1)

[Claims] (1) Depending on the required pumping capacity from the fluctuating process,
The first stage compressor is adjusted by Furukawa, and the second stage rE compressor is adjusted by Furukawa so that the optimal intermediate stage pressure is reached at which the power consumption of the compressor drive machine is minimized at the adjusted capacity. A method for adjusting the capacity of a positive displacement two-stage compressor, characterized by: