JPS6358067A - Method of controlling turbo refrigerator - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for controlling a turbo chiller in which refrigerant from an evaporator is compressed using a turbo compression margin and guided to a condenser.

BACKGROUND ART In general, the capacity control of a turbo chiller includes rotational speed control of the turbo compressor and suction valve control of the turbo compressor.The former has high efficiency, but the control range is limited. The latter is characterized by low efficiency but a wide control range.In order to bring out the advantages of both, composite control as shown in FIG. 3 has been proposed. In FIG. 3, curves A and B show the relationship between the condensing pressure and load of the centrifugal chiller at a rotation speed of 11,
Point A is the starting point of the sur song. As this rotational speed is decreased, point A changes from 1, fox A1 to A3. When the suction valve is throttled at 0 rotational speed n moving to A2, 1
．． - χA moves from point C and; Qi[).

From this, points B, A, A2. In the rare working region of B2 and U5, capacity control can be performed by rotational speed alone. Also lit, A, A2. In the operating region D2 and the operating regions below points B 2 , A 2 , C2, and D 2 , it is necessary to control the suction valve. On this occasion,
For example, at point E on the curve PQ where the brine temperature is constant, Sarno White #1lB3. A3. Any rotational speed may be used as long as it is higher than the rotational speed 01 of D3, but the efficiency increases as the rotational speed is lowered. Such a phenomenon has been known for a long time, and techniques for saving energy have been developed based on this phenomenon.

As a typical prior art, for example, Japanese Patent Publication No. 44-39
There is 3G. This prior art is provided with a limit switch that is activated by a load s1 that requires suction valve control, and on the right side of this, the suction valve is fully opened to control the rotational speed. To the left of this load 31, as the load decreases, the suction valve is throttled, and the rotation speed increases in conjunction with this.
The rotation speed is set to be maximized when the suction valve reaches its minimum opening. Figure 4 (1) shows the opening degree of this suction valve depending on the load.
1 (2) shows the rotational speed of the turbo compressor in correspondence with the load.

This prior art has the following problems.

In other words, the brine temperature is not always constant;
When the brine temperature or outside air temperature changes, point S
moves on lines A and A2, so if the determination is based only on the load, the control range will be extremely limited. In addition, it is extremely difficult to change the suction valve opening degree and rotation speed at the same time and move it smoothly over point PQ, and if the load suddenly changes, surging may occur due to mutual interference between the suction valve and the braking speed. There is a high risk of

Another prior art is Japanese Patent Publication No. 52-13942. This prior art has a configuration in which load adjustment is performed by a suction valve and rotational speed control is changed depending on a change in brine temperature. In this prior art, control is performed to the left of the line connecting points A and A2 in the f:trJ3 diagram, and the right region where load control is performed by rotational speed is not achieved, and the control range is limited. The problem is that it's narrow.

Problems to be Solved by the Invention An object of the present invention is to provide a control method for a centrifugal chiller that can save energy, expand the capacity control range, and reliably prevent surging. It is to be.

Means for resolving three problems The present invention compresses the refrigerant from the evaporator with a turbo compressor and guides it to the condenser, detects the condensing pressure and load, and based on the detection results of both, rotates the refrigerant. In a method for controlling a turbo chiller, which has a Pt51 operation region that controls the speed and a Pt52 operation region that controls the suction valve provided at the suction port of the turbo compressor, in the second operation region, the Pt52 operation region is Divide the area into multiple head-mounted parts corresponding to the rotational speed, set the rotational speed for each of the seven areas, and when moving between the r51 and f52 movement areas,
In the 52nd movement range, the rotation of 11 degrees was changed slowly until the rotation speed of each area was reached without causing any disturbance to the valve control. This method of controlling a centrifugal chiller is characterized in that the valve is opened slowly until it is fully opened.

According to the present invention, when the rotational speed of the turbo compressor is in an operating range where the speed can be controlled, the rotational speed is controlled with the suction valve kept fully open, thereby making it possible to efficiently control the capacity. .

When the operating range is such that surging occurs and operation cannot be achieved by controlling the rotational speed by only $11, the valve stroke is controlled while the rotational speed is reduced as much as possible. Therefore, it is possible to expand the capacity control range while saving energy.

Further, in the present invention, fjSl! When moving from the e operation area to the fjS2 operation area, change the rotation speed to the second! Change the suction valve control slowly to the extent that no disturbance is applied (r) until the rotation speed reaches the set rotation speed for each of the plurality of regions divided in the IJJ region 1i. When moving from the area to the first movement area, the suction valve is opened slowly until it is fully open without adversely affecting the speed control of the rotary plate.In this way, surson can be reliably prevented. .

Example 112I is a system diagram of an embodiment of the present invention.

This turbo refrigerator comprises a turbo compression method 2 performed by a heat engine 1, such as an internal combustion engine. Refrigerant from the evaporator 4 is supplied to the inlet 3 of the turbo compression fi2. The refrigerant from the outlet 5 of the turbo pressure jll12 is sent to the condenser 6 and returns to the evaporator 4 via the expansion valve 7. The pressure of the refrigerant in the condenser 6, that is, the condensation pressure, is detected by a pressure detector 8. The temperature T1 at the brine outlet of the evaporator 4 and the temperature T2 at the brine inlet are detected by temperature detectors 9 and 10, respectively.

The rotational speed of the heat engine 1 is detected by a speed detector 11. These detectors 8,9.10. The output from the control circuit 11 is input to the control circuit 12, thereby controlling the control circuit 1.
2, the heat is controlled by the governor 13 which is 1,000 f2 to control the rotational speed of the flash 1, and the angle of the vane of the suction valve 14 provided at the suction port of the turbo compression method 2 is controlled. The opening degree of the suction valve 14 is controlled. The brine flow rate of the evaporator 4 is constant.

Figure 2 is a graph showing the relationship between load/condensing pressure for turbo refrigeration.A line connecting points A and B, point A
1.81, and the point A2. The line connecting B2 shows the characteristics when only the rotational speed is changed with the suction valve 14 fully open, and the line at points A and I3 shows the state at the maximum rotational speed of the heat engine 1. Point A
2. Line B2 shows the state at the minimum rotation speed. The line connecting points A and A2 is a line connecting the cerning starting points at each rotational speed. Thus points B, A, A2.
In the first operating region Z1 surrounded by B2, the suction valve 1,
The centrifugal chiller can be controlled only by the rotational speed with t fully open, and high efficiency can be achieved.

, fi A to the left of the line connecting A and A2 shows the characteristics when the opening degree of the suction valve 14 is controlled, and is a point A.

Lines C and D indicate the state at maximum rotational speed, and point Δ
2, C2, and D2 lines indicate the state at the lowest rotational speed. Points B 2 , A 2 , C2, D 2 and below are defined as area portion Z2, and points DI, C1, A1 . A2. C2,
Let D2 be the area part Z3, points C, A, A 1 , C
1, let Dl be the area portion z4, and let these area portions Z2°Z3. Z4 will be referred to as the second desired motion range. This second
In the operating region, the opening degree is controlled by the vane of the suction valve 14. In the control circuit 12, point A.

B; A, A2; A2. B2; A, D; Al, Di; A2
．． Memorize all lines such as D2. This control circuit 12 controls the condensation pressure detected by the pressure sensor 8 and the brine temperature T1. detected by the temperature sensor 9.10. T2 and the actual operation is performed in the first operation region Z1 and [2 area portions Z 2 , Z 3 of the second operation region Z 2 , Z 3
, determine where in Z4 the process is being performed. tPJ
When the operation enters the IT region Z1, the suction valve 14 is fully opened and the rotational speed is controlled so that the line outlet temperature T1 measured by the temperature detector 9 becomes a predetermined constant value.

Among the region portions Z 2 , Z 3 , and Z 4 of the second operation region, in the region portion Z2, the rotation speed is changed to the region portion z2.
The suction valve is controlled so that the brine outlet temperature T1 becomes a predetermined constant value.

Remaining area portion 23. Although Z4 also performs the same control as the one-zone portion Z2, the rotational speed in each zone portion Z3+7.4 is set to the maximum value n3+n4 in the zone portions Z3 and Z4, respectively.

At the moment when the first operation area and @2 operation area are mutually moved, a change in the opening degree of the suction valve and a change in the rotation speed will occur at the same time, and there is a risk that the control will not be able to be performed normally. There is. In order to solve this problem, in the present invention, each area portion Z 2 of the second operating area where the load is controlled by the suction valve 14 is
, Z 3 , and Z 4 (first, the rotational speed is changed slowly enough to reach the target rotational speed so as not to affect the control effect of the suction valve 14; also, in the region zl).

Z3. From the 12 operation areas consisting of Z4, the first operation fii
When moving to area Z1, rotation j! in the first movement area Z1! ! The VD construction and the suction valve 14 are opened to such an extent that no deformation occurs in the control effect, and finally, the suction valve 14 is fully opened. In this way smooth operation can be achieved.

As another embodiment of the present invention, in order to prevent hunting motion, boundaries for determining the region portions Z 2 , Z 3 , Z 4 of the first motion region Z1 and the second motion region include:
A so-called hysteresis may be provided, ie from the first operating region Z1 to the region portion Z3. When moving to Z4, point A
, the line A2 is the boundary, and in the opposite case, the line! 1 is the boundary. Further, when moving from the region Z2 to the Pt51 operating region Z1 or the region Z3, the boundary is moved to the point A 2 , B 2 :A2. The lines are C2 and D2, and when moving from the area Z3 to the area Z4, the lines are the points A 1 , C1, and Dl. First operating area 2
1 and when moving from area portion Z3 to area portion Z2, the boundary is drawn by line 12. 3, and when moving from area Z4 to area Z3, draw the boundary as a line! 4.

The second operating region consists of three region portions Z in the embodiment described above.
Although it was divided into 2, Z 3, and Z 4, it would be even better to divide it further and make the operation control more efficient.

In the above embodiment, the load on the frozen rock is detected based on the temperature difference (T2-TI) of the brine, but the load may also be detected based on the configuration of the pond.

Effects As described above, according to the present invention, when the rotation speed is in the controllable operation range, the rotation speed is controlled while the vane provided at the suction port is kept fully open, thereby increasing the capacity with high efficiency. can be controlled. In addition, when the operating range is such that the rotation speed cannot be increased by controlling the rotation speed alone, the valve throttle is controlled while the rotation speed is reduced as much as possible, resulting in energy savings. At the same time, turbo compression can operate stably over a wide range.

Moreover, according to the present invention, there are 11 operating regions! Control during movement between the 52 and 52 operating areas is performed smoothly, and there is no possibility of surging or the like occurring.

[Brief explanation of the drawing]

Figure 1 is a block diagram of an embodiment of the present invention, and Figure 2 is! :
tS1 is a graph for explaining the operation of the turbo-refrigerated rock shown in Figure 3. Figure 3 is a graph for explaining the operation of the prior art. Figure 4 is a graph for explaining the prior art. It is a graph showing the relationship between speed and load. DESCRIPTION OF SYMBOLS 1... Heat engine, 2... Turbo compressor, 3... Suction port, 4... Evaporator, 5... Outlet, 6... Condenser, 7... Expansion valve, 8 ...Pressure detector, 9.10...
・Temperature detector, 11...Rotation speed detector, 12...
Control plane road, 13...〃Bana, 1/t...Suction valve agent Patent attorney Saikyo Keiichi Part 1 Figure 2 Shell word 3 Prison load

Claims (1)

[Claims] A first operating region in which the refrigerant from the evaporator is compressed by a turbo compressor and guided to the condenser, the condensation pressure and load are detected, and the rotation speed is controlled based on the detection results of both. and a second operating region for controlling the suction valve provided at the suction port of the turbo compressor, in which the second operating region is controlled in accordance with the rotational speed. It is divided into a plurality of areas, and the rotational speed is set for each area. When moving between the first and second operating areas, the rotational speed is set to the rotational speed of each area in the second operating area. In the first operating region, the valve is slowly opened until it is fully open without causing any adverse effects on the rotational speed control. How to control a centrifugal chiller.