JP2000110793A - Gas temperature control method in compressor and compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain complete vaporization of a cooling fluid at all times by controlling the amount of the cooling fluid sprayed based on the measurement taken by a steam volume sensor installed in a return flow path of a compressor of the amount of seam of the cooling fluid in a gas to be compressed. SOLUTION: A fluid level sensor 18 measures the amount of drain accumulated in the bottom of a return corner 6 in a return flow path 4. At the same time, a temperature sensor 16 measures the temperature of a gas to be compressed. Next, it is determined if the amount of drain measured exceeds a predetermined level. It is also determined if the difference between the temperature measured of the gas to be compressed and that of the gas to be compressed on the upstream end of an injection nozzle 12 exceeds a predetermined level. If the amount of drain is excessive, or if the temperature difference exceeds the predetermined level even with an adequate amount of drain, the cooling fluid is not sprayed, or the spurt is stopped if it has already been sprayed. If, on the other hand, the amount of drain is adequate and the temperature difference is below the predetermined level, the cooling fluid is sprayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applicable to various chemical plants, for example, as a cracked gas compressor for an ethylene plant or a process gas compressor for a butadiene plant, or as a compressor or an air compressor for various refrigeration cycles. The present invention relates to a compressor that can be used, and particularly to a compressor that can control the temperature of a gas to be compressed by spraying a cooling liquid onto the gas to be compressed.

[0002]

2. Description of the Related Art A centrifugal compressor, which is one of the typical compressors for compressing gas, compresses a gas to be compressed from a suction pipe while rotating an impeller fixed on a rotating shaft in multiple stages. At the same time, the compression target gas is compressed by applying compression energy to the compression target gas by rotation of the impeller. In such a compressor, it is difficult to avoid that the temperature of the gas to be compressed rises with the compression.

For example, when a centrifugal compressor is used as a cracking gas compressor for an ethylene plant, when the temperature of the gas to be compressed rises to a certain temperature or higher, a polymer having a high viscosity is generated by polymerization of the cracking gas. It adheres to the walls of the impeller and the return flow path that is the flow path of the gas to be compressed. As a result, the flow path area of the gas to be compressed is reduced, and the performance is reduced as the compression efficiency is reduced. For this reason, the compressor generally controls the temperature of the compression target gas by spraying a cooling liquid on the compression target gas.

A conventional general configuration for such temperature control is as follows. That is, a cooling liquid spray unit is provided in the return flow path, and a required amount of the cooling liquid is sprayed onto the gas to be compressed while controlling the control unit by the control unit. As a standard for controlling the spray amount by the control means, a gas weight flow rate measured by a gas weight meter in the suction pipe is used, and usually a maximum of 3 w
The control was performed with about t% as a guide. That is, the required amount of the cooling liquid is controlled at a predetermined weight ratio according to the amount of the gas to be compressed actually taken in by the compressor.

[0005]

In the conventional control described above, the spray amount of the cooling liquid is controlled based on a theoretical guess using only the amount of the gas to be compressed actually taken in by the compressor as an index. is there. For this reason, depending on the actual operation state of the compressor, the spray amount of the cooling liquid may become excessive and the cooling liquid may not be completely vaporized, and the following problems are caused accordingly. . That is, when the cooling liquid that cannot be vaporized flows through the return flow path in a gas-liquid mixed state, the erosion of the impeller is more likely to occur. In addition, the flow of the gas-liquid mixture generates an uneven flow in the return flow path, which serves as a vibration source for the impeller, which may cause unstable vibration and even damage. In addition, if the cooling liquid contains non-vaporized components, the amount of drain generated increases, and this drain accumulates in the lower part of the return flow path, thereby reducing the flow path area of the gas to be compressed and causing performance degradation. .

[0006] Regarding such problems in the prior art, efforts have been made to solve the problems, for example, as disclosed in Japanese Unexamined Patent Publication No. Hei.
This has already been done, as can be seen in US Pat. The technique disclosed in Japanese Patent Application Laid-Open No. H10-018976 calculates not only the intake amount of the gas to be compressed but also the theoretical saturation amount of the part where the cooling liquid is sprayed, and controls the spray amount of the cooling liquid based on these indices. In this way, incomplete vaporization is prevented. However, this technique is also basically based on a theoretical guess, and there is insufficient control of the spray amount of the cooling liquid so as to be optimal under the actual operation state of the compressor.

[0007] Excessive accumulation of drain in the return flow path as described above also leads to a decrease in the performance of the compressor, but none of the prior arts takes account of this problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and has been described for a compressor which controls the temperature of a gas to be compressed. The purpose of the present invention is to provide a gas temperature control method that enables complete vaporization of gas, and to provide a compressor that can execute such a gas temperature control method. It aims to provide a compressor that can handle it.

[0009]

To achieve the above object, the present invention relates to a gas temperature control method for a compressor, which controls the temperature of a gas to be compressed by spraying a cooling liquid onto the gas to be compressed. The amount of vapor of the cooling liquid in the gas to be compressed is measured by a vapor amount sensor provided in a return flow path of the compressor, and the spray amount of the cooling liquid can be controlled based on the measurement result. And

[0010] To achieve the above object, the present invention provides:
In a compressor configured to control the temperature of the gas to be compressed by spraying a cooling liquid onto the gas to be compressed, a vapor amount sensor provided in a return flow path for the gas to be compressed; Control means for controlling a spray amount of the cooling liquid based on a vapor amount of the cooling liquid in the compression target gas measured by an amount sensor.

[0011] In order to achieve the above object, the present invention provides:
In a compressor adapted to control the temperature of the gas to be compressed by spraying the cooling liquid onto the gas to be compressed, in order to detect the amount of the cooling liquid accumulated in the return flow path for the gas to be compressed Is characterized in that it is provided with a liquid amount sensor.

[0012] To achieve the above object, the present invention provides:
In a compressor configured to control the temperature of the gas to be compressed by spraying a cooling liquid onto the gas to be compressed, a vapor amount sensor provided in a return flow path for the gas to be compressed; Control means for controlling a spray amount of the cooling liquid based on a vapor amount of the cooling liquid in the gas to be compressed measured by an amount sensor, and a liquid for detecting a liquid amount of the cooling liquid accumulated in the return flow path And a quantity sensor.

According to the gas temperature control method and the compressor of the present invention, the vaporization state of the cooling liquid is directly detected by the vapor amount sensor in the return flow path, and the spray amount of the cooling liquid is controlled based on this. As a result, it is possible to substantially eliminate the possibility of incomplete vaporization of the cooling liquid even under an actual operating condition, and to prevent the occurrence of the various problems described above due to the incomplete vaporization of the cooling liquid. Can be avoided.

Further, according to the compressor of the present invention, the amount of the cooling liquid accumulated in the return passage can be directly detected by the liquid amount sensor. , This condition can be reliably detected, and if necessary, measures such as temporarily stopping the operation of the compressor and draining excess drain can be taken promptly. Can be avoided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 and FIG. 2, which is a partially enlarged view, show essential parts of a compressor according to an embodiment of the present invention. As shown in FIG. 1, the compressor according to the present embodiment is a single-shaft multi-stage centrifugal compressor, and a plurality of compression stages are formed on a rotating shaft 2 supported by a compressor casing 1 in the axial direction thereof. (In the example of the figure, four) impellers 3 (3a to 3d) are fixedly provided. Each impeller 3 has a return flow path 4 whose tip is a flow path of a gas to be compressed.
(4a to 4d). Return channel 4
Are a diffuser 5, which is a downstream portion of the impeller 3, a return corner 6, which is a downstream portion of the diffuser 5, and a downstream portion of the return corner 6, which rectify a gas flow into an optimal flow and convert the gas flow into an optimal flow. Return vane 7 flowing into the car
The airtightness is maintained by a stage labyrinth 8 and an impeller eye labyrinth 9.

The gas to be compressed flowing through the suction pipe 11 is pressurized by the rotation of the foremost impeller 3a.
It is discharged from there. The gas to be compressed discharged from the impeller 3 a flows into the diffuser 5 and returns to the return corner 6.
And returns to the return vane 7, from which it flows into the next stage impeller 3b. The same is repeated from the impeller 3b onward, and each time, the velocity energy of the gas to be compressed becomes pressure energy due to the change in the gas flow in the return flow path 4 which is stationary with respect to the impeller 3 which is dynamic. Compression is done by being changeable.

In this process, the temperature of the gas to be compressed increases, but the gas to be compressed is cooled by spraying a cooling liquid so that the temperature does not exceed a certain level. For this purpose, a temperature control system is provided for cooling the gas to be compressed with a cooling liquid, such as water, which can evaporate at a normal temperature in the gas to be compressed.

As shown in FIGS. 1 and 2, the temperature control system includes a spray nozzle 12 for spraying a cooling liquid onto a gas to be compressed in a return passage 4, and a supply amount of the cooling liquid to the spray nozzle 12. A control valve 13 for controlling, a flow controller 14 for controlling the control valve 13, a cooling liquid supply tank 15, and a return flow path downstream of the spray position of the cooling liquid by the spray nozzle 12 and before reaching the next stage impeller 3. 4, a temperature sensor 16 for detecting the temperature of the gas to be compressed, the cooling liquid in the gas to be compressed in the return flow path 4 downstream of the spray position of the cooling liquid by the spray nozzle 12 and shortly before reaching the next impeller 3. Sensor 17 for detecting the amount of vapor of the liquid, a liquid amount sensor 18 for detecting the amount of drain collected at the bottom of the return flow path 4, Comprising gas weight meter 19 for measuring the weight flow rate of the gas.

A commercially available sensor can be used for any of the above sensors. For example, as for the vapor amount sensor 17, a polymer film moisture-sensitive element is used if water is used as the cooling liquid. It is preferable to use a probe-type sensor capable of converting a humidity of 10 to 90% ph into an electric signal under various gas atmospheres and outputting the electric signal. It is desirable that the relationship between the vapor amount sensor 17 and the spray nozzle 12 is such that the sprayed cooling liquid does not directly impinge on the vapor amount sensor 17. The spray nozzle 12 is so sprayed that the cooling liquid is sprayed at a slightly shifted position.
Should be provided.

In such a temperature control system, the temperature information on the gas to be compressed obtained by the temperature sensor 16, the vapor amount information of the cooling liquid in the gas to be compressed obtained by the vapor amount sensor 17, the liquid amount sensor 18 The information on the amount of drain in the return flow path 4 obtained in the step (b) and the information on the weight flow rate of the gas to be compressed obtained by the gas weighing scale 19 are stored in the flow controller 14.
Provided to Then, the flow rate controller 14 determines the required spray amount of the cooling liquid and the necessity of the spray based on the information, and controls the control valve 13 based on the calculated spray amount.

Hereinafter, the details of this control will be described with reference to a flowchart shown as an example in FIG. First, the amount of drain collected at the bottom of the return corner 6 in the return flow path 4 is measured by the liquid amount sensor 18, and the temperature of the gas to be compressed is measured by the temperature sensor 16. Next, it is determined whether or not the drain amount L measured by the liquid amount sensor 18 does not exceed a predetermined amount (for example, 10-5 m3). At the same time, whether the temperature difference ΔT between the temperature of the gas to be compressed measured by the temperature sensor 16 and the temperature of the gas to be compressed upstream of the spray nozzle 12 is equal to or more than a predetermined value (for example, 10 ° C. or more), Alternatively, it is determined whether the temperature of the compression target gas measured by the temperature sensor 16 is equal to or higher than a predetermined temperature. In the former case, information from a temperature sensor provided separately from the temperature sensor 16 is also used to detect the temperature of the gas to be compressed on the upstream side of the spray nozzle 12.

If the amount of drain is excessive, the cooling liquid is not sprayed (in the case of an initial start), or is stopped if the cooling liquid has already been sprayed. In this case, it is desirable to perform draining or the like by stopping the operation of the compressor as necessary. Even if the amount of drainage is not excessive, if the temperature difference ΔT is equal to or more than a predetermined value (or if the temperature of the gas to be compressed is equal to or less than a predetermined temperature), that is, if the gas to be compressed has a risk If the temperature is not accompanied by the above, the spraying of the cooling liquid is not performed, or the spraying is stopped if the cooling liquid has already been sprayed.

Conversely, if the amount of drain is not excessive, the temperature difference ΔT
If is also equal to or lower than the predetermined value (or if the temperature of the gas to be compressed is equal to or higher than the predetermined value), the cooling liquid is sprayed at the A level. At this A level, usually, for example, 3 wt% of the weight flow rate of the gas to be compressed taken into the compressor.
The cooling liquid is sprayed in such an amount that:

While the operation is continued in this state, the vapor amount of the cooling liquid in the gas to be compressed is measured by the vapor amount sensor 17, and it is determined whether or not the result is a predetermined amount or less (for example, 85% or less). Ask for. If the vapor amount is equal to or less than the predetermined amount, spraying of the cooling liquid at the A level is continued.
On the other hand, when the vapor amount is equal to or more than the predetermined amount, the possibility of incomplete vaporization of the cooling liquid increases, so the cooling liquid spray amount at a level lower than the cooling liquid spray amount at the A level (For example, 90% of A level or less).

[0025]

According to the present invention, in a compressor adapted to control the temperature of a gas to be compressed, a cooling liquid sprayed for cooling the gas to be compressed is cooled regardless of the operating state of the compressor. Therefore, it is possible to always completely vaporize, and it is possible to effectively avoid various problems due to incomplete vaporization of the cooling liquid.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a compressor according to the present invention.

FIG. 2 is an enlarged view of a part of FIG.

FIG. 3 is a flowchart relating to temperature control in the compressor of FIG. 1;

[Explanation of symbols]

 4 Return flow path 14 Flow controller (control means) 17 Vapor amount sensor 18 Liquid amount sensor

Continued on the front page (72) Inventor Hideki Matsuno 603, Kandamachi, Tsuchiura-shi, Ibaraki F-term in Tsuchiura Plant, Hitachi Ltd. (Reference) 3H045 AA06 AA13 AA25 BA00 CA00 CA29 DA00 EA43

Claims (4)

[Claims] 1. A method for controlling the temperature of a gas to be compressed by spraying a cooling liquid onto the gas to be compressed, wherein the temperature of the gas to be compressed is controlled by a vapor amount sensor provided in a return flow path of the compressor. A gas temperature control method, comprising: measuring a vapor amount of a liquid in a gas to be compressed; and controlling a spray amount of the cooling liquid based on the measurement result. 2. A compressor according to claim 1, wherein the cooling liquid is sprayed onto the gas to be compressed to control the temperature of the gas to be compressed. A compressor comprising: a sensor; and control means for controlling a spray amount of the cooling liquid based on a vapor amount of the cooling liquid in the compression target gas measured by the vapor amount sensor. 3. A compressor for controlling the temperature of a gas to be compressed by spraying the cooling liquid onto the gas to be compressed, wherein the liquid of the cooling liquid accumulated in a return flow path for the gas to be compressed is provided. A compressor comprising a liquid amount sensor for detecting an amount. 4. A compressor in which a cooling liquid is sprayed on a gas to be compressed to control the temperature of the gas to be compressed, wherein the amount of steam provided in a return flow path for the gas to be compressed is controlled. A sensor, control means for controlling a spray amount of the cooling liquid based on a vapor amount of the cooling liquid in the compression target gas measured by the vapor amount sensor, and a liquid amount of the cooling liquid accumulated in the return flow path. A compressor comprising a liquid amount sensor for detecting.