JPH10246522A - Screw type freezer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a stable operation to be carried out under a less amount of consumption power and while keeping a viscosity of refrigerant required for a bearing in a main body of a compressor by a method wherein a temperature of the refrigerant supplied to the main body of the compressor in a screw type freezing machine is kept at a specified temperature. SOLUTION: A secondary side of an evaporator 5 is provided with a thermo-sensitive cylinder 11 for sensing a degree of superheat of refrigerant at this part and adjusting a degree of opening of a first expansion valve 4 in such a way that this degree of superheat may become a value of set range. A section of a refrigerant dividing flow passage III at the secondary side of a refrigerant cooling device 6 is provided with a thermo-sensitive cylinder 12 for sensing a degree of superheat and for adjusting a degree of opening of a second expansion valve 8 in such a way that the detected degree of superheat may become a value of set range, for example, 5 deg.C of the degree of superheat. A temperature of the fed refrigerant can be kept in a range of about 60 to 80 deg.C by adjusting a degree of superheat of the refrigerant at the secondary side of a refrigerant cooling device 6 under an operation of a second expansion valve 8. Due to this fact, a consumption power can be reduced and a stable operation can be assured by keeping a viscosity of refrigerant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw refrigerator in which oil supplied to an oil-cooled screw compressor body is cooled by a refrigerant.

[0002]

2. Description of the Related Art Conventionally, a refrigerator shown in FIG. 5 is known as a refrigerator in which oil supplied to an oil-cooled compressor body is cooled by a refrigerant (Japanese Patent Application Laid-Open No. H4-177059).
This refrigerator has a two-stage oil-cooled compressor main body 21, an oil separation and recovery unit 22, a condenser 23, a liquid receiver 24, a subcooler 25,
A closed refrigerant circulation flow path X including an expansion valve 26 and an evaporator 27, an oil supply flow path Y from the oil separation and recovery unit 22 to an oil supply point in the compressor body 21 via the oil cooler 28, Branching off from the circulation flow path X in the compressor 24, passing through the on-off valves 29, 30, the expansion valves 31, 32, and further through the oil cooler 28, into the intermediate pressure region in the compressor body 21, A refrigerant branch flow path Z that reaches an intermediate flow path portion between the stage compressor main body and the second stage compressor main body is provided.

Then, an oil supply passage Y
Heat is exchanged between the internal oil and the refrigerant in the refrigerant branch channel Z to cool the oil to 40 to 60 ° C. and guide the oil to the oil supply point. This refrigerator is of a two-stage type. However, considering a similar structure to the single-stage screw compressor main body 41 as shown in FIG. 6, the refrigerant after heat exchange with oil in an oil cooler is performed. Gas oil is supplied to the screw rotor 42
The gas is supplied to the gas compression space 44 of the space formed between the casing and the casing 43, that is, the gas confined space that does not communicate with any of the suction port 45 and the discharge port 46.

[0004]

In the case of the above-described conventional refrigerator shown in FIG. 5, the cooling refrigerant flowing into the oil cooler 28 passes through the oil cooler 28, becomes a gas state, and becomes a gas state. Guided to the pressure zone, the oil is cooled to 40-60 ° C. On the other hand, as will be described later, when the oil supply temperature into the compressor main body 21 decreases, a problem arises in that the power consumption in the compressor main body 21 increases. In the case of a refrigerator using the single-stage screw compressor main body 41 shown in FIG.
Since the refrigerant gas from the oil cooler flows into the gas compressor space 44 that is not communicated with the gas compressor space 44, the larger the flow rate, that is, the stronger the oil cooling, the greater the gas compression space 44.
The pressure at increases. As a result, the amount of gas leaking to the suction port 45 increases, and the gas must be further compressed, which causes a problem that power consumption in the compressor body 41 increases. SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned conventional problems, and has a low power consumption and secures the viscosity of oil necessary for a bearing in a compressor body to enable stable operation. It is intended to provide an improved screw refrigerator.

[0005]

In order to solve the above-mentioned problems, a first invention includes at least an oil separation and recovery unit, a condenser, a first expansion valve, and an evaporator in addition to an oil-cooled screw compressor main body. Oil supply from the closed circulation flow path of the refrigerant and the oil reservoir at the lower part of the oil separation and recovery unit, through the oil cooler, to the oil supply points such as the rotor housing space in the compressor body, bearings and shaft seals A flow path, a portion of the circulation flow path between the condenser and the first expansion valve, which branches off from a portion of the circulation flow path, passes through a second expansion valve, and exchanges heat with oil in the oil supply flow path through the oil cooling. After passing through the interior of the compressor, the branch flow path for the refrigerant reaching the gas compression space in the compressor main body, and the degree of superheat of the refrigerant in the branch flow path is detected at the secondary side of the oil cooler. The degree of superheat is adjusted to a range necessary for maintaining the temperature of oil supplied to the compressor body at 60 to 80 ° C. A feeler bulb adjusting the opening of the second expansion valve so that the value of the inner formed by providing.

A second invention provides a closed refrigerant flow path including at least an oil separation and recovery unit, a condenser, a first expansion valve and an evaporator, in addition to the oil-cooled screw compressor main body, An oil supply flow path from an oil reservoir at a lower portion of the recovery device to an oil supply point such as a rotor housing space in the compressor body, a bearing / shaft seal portion, etc., through an oil cooler, the condenser and the first expansion After branching from the portion of the circulation flow path between the oil supply passage and the temperature control flow control valve, and passing through the oil cooler so as to be able to exchange heat with oil in the oil supply flow path, the compressor The branch passage for the refrigerant reaching the gas compression space in the main body, between the oil cooler and the compressor body, detects the temperature of the oil in the oil supply passage, based on the detected temperature, The value of the oil supplied to the compressor body should be within a range necessary for maintaining the temperature of the oil at 60 to 80 ° C. It was formed by providing a temperature sensing tube for adjusting the opening degree of the flow rate control valve so.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a screw refrigerator according to a first invention, in which closed circulation of refrigerant including an oil-cooled screw compressor main body 1, an oil separation and recovery unit 2, a condenser 3, a first expansion valve 4, and an evaporator 5 is shown. Oil supply flow path II from flow path I to an oil supply point such as a rotor housing space in the compressor main body 1, a bearing / shaft seal part, etc., from an oil reservoir at a lower portion of the oil separation and recovery unit 2 through an oil cooler 6. And an orifice 7 branching from a portion of the circulation flow path I between the condenser 3 and the first expansion valve 4 and being an example of a throttle valve.
After passing through the oil cooler 6 through the second expansion valve 8 and the oil in the oil supply flow path II so as to be able to exchange heat with the oil, the gas compression space in the compressor body 1, that is, the suction port and the discharge port as described above. Refrigerant branch channel III leading to gas confined space not communicating with any of
Are formed.

Further, on the secondary side of the evaporator 5, the degree of superheat of the refrigerant in this portion is detected, and the opening of the first expansion valve 4 is adjusted so that the degree of superheat falls within a set range. Temperature sensing cylinder 1
1 is provided. Branch flow path for refrigerant on the secondary side of oil cooler 6
In part III, the degree of superheat of the refrigerant in this part is detected,
The detected superheat degree is a value within a set range, for example, superheat degree 5
Temperature-sensitive cylinder 1 for adjusting the opening degree of the second expansion valve 8 so that the temperature becomes 1 ° C.
2 are provided.

FIG. 2 shows the result of a test on the relationship between the temperature of oil supply to the compressor body 1 (horizontal axis: ° C.) and the power consumed by the compressor body 1 (vertical axis: kw). The consumption power decreases with the rise of. For example, from this figure, the refueling temperature is 53 ° C. and the power consumption is 44.7 kw.
It can be seen that kw and the refueling temperature are reduced by 9% as compared with the case of 53 ° C. FIG. 3 shows the relationship between the lubricating temperature (horizontal axis: ° C.) and the viscosity of the oil under the lubricating condition (vertical axis: cst). If the temperature exceeds 80 ° C, the minimum required for bearings is 10c.
It turns out that the viscosity of st is not ensured. As described above, in FIG. 2, the power consumption is relatively large in the range indicated by A, the viscosity of the oil cannot be ensured in the range indicated by C, and the range indicated by B, that is, the oil supply temperature range of 60 to 80 ° C. It can be said that the power is relatively small and the viscosity is in an optimum range in which the viscosity of the oil can be ensured.

In the above screw refrigerator, the refueling temperature is maintained in the range of 60 to 80 ° C. by adjusting the degree of superheat of the refrigerant on the secondary side of the oil cooler 6 by the second expansion valve 8, and the power consumption is reduced. The stable operation can be performed by reducing the oil content and securing the viscosity of the oil. In the embodiment described above, the fixed throttle orifice 7 is provided, but the first invention of the present application does not necessarily require the orifice 7.

FIG. 4 shows a screw refrigerator according to the second invention. The screw refrigerator shown in FIG.
A temperature control flow control valve 9 is provided in place of the second expansion valve 8,
Except that a temperature sensing tube 13 is provided in place of the temperature sensing tube 12, the other portions are substantially the same, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. In this screw refrigerator, the temperature of the oil supplied to the compressor body 1 is detected, and based on the detected temperature, it is necessary to maintain the temperature of the oil supplied to the compressor body 1 at 60 to 80 ° C. The opening of the flow rate control valve 9 is adjusted so as to have a value within a suitable range. With such a configuration, stable operation can be performed by reducing the power consumption and ensuring the viscosity of the oil, as in the first invention.

In each of the above-described embodiments, the condenser 3 is integrated with the receiver, but the present invention does not limit the type of the condenser 3 of the present invention. It may be of a separate type.

[0013]

As is apparent from the above description, according to the present invention, the temperature of the oil supplied to the compressor body of the screw refrigerator is maintained at 60 to 80 ° C. For this reason, it is possible to secure the viscosity of the oil necessary for the bearing in the compressor main body with a small power consumption and to achieve an effect such that a stable operation becomes possible.

[Brief description of the drawings]

FIG. 1 is a view showing an entire configuration of a screw refrigerator according to a first invention.

FIG. 2 is a diagram showing a result of actual measurement on a relationship between a refueling temperature and power consumption in a compressor body.

FIG. 3 is a diagram showing a relationship between oil supply temperature and oil viscosity under an oil supply state.

FIG. 4 is a view showing the overall configuration of the screw refrigerator according to the first invention.

FIG. 5 is a diagram showing an entire configuration of a refrigerator using a conventional oil-cooled compressor main body.

6 is a diagram showing a return position of a refrigerant gas from an oil cooler when a structure similar to the refrigerator shown in FIG. 5 is applied to a single-stage screw compressor main body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Screw compressor main body 2 Oil separation and recovery unit 3 Condenser 4 First expansion valve 5 Evaporator 8 Second expansion valve 9 Flow control valve 12, 13 Thermosensitive cylinder I Circulation channel II Oil supply channel III Branch flow for refrigerant Road

Claims (2)

[Claims] 1. An oil-cooled screw compressor main body, a closed circulation flow path of a refrigerant including at least an oil separation and recovery unit, a condenser, a first expansion valve and an evaporator, and a lower part of the oil separation and recovery unit. An oil supply passage extending from an oil reservoir to an oil supply point, such as a rotor housing space in the compressor body, a bearing / shaft seal, or the like, through an oil cooler, and an oil supply passage between the condenser and the first expansion valve. After branching from the portion of the circulation flow path, passing through the oil cooler through the second expansion valve so as to be able to exchange heat with the oil in the oil supply flow path, the oil flows into the gas compression space in the compressor body. In the refrigerant branch flow path and the secondary side of the oil cooler, the degree of superheat of the refrigerant in the branch flow path is detected, and the degree of superheat is determined by the amount of oil supplied to the compressor body. Temperature sensing for adjusting the opening of the second expansion valve so that the temperature is kept within a range necessary for maintaining the temperature at 60 to 80 ° C. A screw refrigerating machine formed by providing a tube. 2. An oil-cooled screw compressor main body, a closed circulation flow path of a refrigerant including at least an oil separation and recovery unit, a condenser, a first expansion valve and an evaporator, and a lower part of the oil separation and recovery unit. An oil supply passage extending from an oil reservoir to an oil supply point, such as a rotor housing space in the compressor body, a bearing / shaft seal, or the like, through an oil cooler, and an oil supply passage between the condenser and the first expansion valve. After branching from the part of the circulation flow path and passing through the oil cooler through a temperature control flow control valve and heat exchange with oil in the oil supply flow path, gas compression in the compressor body is performed. The refrigerant branch flow path to the space, between the oil cooler and the compressor main body, detects the temperature of the oil in the oil supply flow path, based on the detected temperature, the compressor main body The above flow rate adjustment is performed so that the temperature of the oil to be supplied is within a range necessary for maintaining the temperature of the oil at 60 to 80 ° C. A screw refrigerator comprising a temperature-sensitive cylinder for adjusting the degree of opening of a node valve.