KR20010045176A - method for control of a solution pump of ammonia absorption heat pumps - Google Patents

Abstract

PURPOSE: A method for controlling operation of liquid pump is provided to protect solution pump by sensing an abnormal operation of the solution pump utilizing rotational frequency of the motor. CONSTITUTION: A method comprises a step(S1) of operating the solution pump by inputting a voltage according to the normal operation condition; a step(S2) of measuring rotational frequency of the motor; a step(S3) of comparing the measured rotational frequency of the motor and the rotational frequency of the motor at the voltage applied in the step(S1), and judging whether the measured rotational frequency of the motor falls within the range of the minimum rotational frequency to the maximum rotational frequency; a step(S4) of proceeding with the operation, adjusting input voltage of the solution pump or adjusting the motor at the lowest speed in accordance with the result of judgement of the step(S3); a step(S5) of measuring again the rotational frequency of the motor after an elapse of a predetermined time period; a step(S6) of comparing the measured rotational frequency of the motor and the rotational frequency of the motor at the voltage input according to the normal operation conditioner, and judging whether the measured rotational frequency of the motor falls within the range of the minimum rotational frequency to the maximum rotational frequency; a step(S7) of proceeding with the normal operation or turning off the motor in accordance with the result of judgement in the step(S6); and a step(S8) of re-starting the solution pump after an elapse of a predetermined time since turn off of the motor.

Description

Method for control of a solution pump of ammonia absorption heat pumps

The present invention relates to an ammonia absorption heat pump, and in particular, when a gear pump is used as a solution pump of an ammonia absorption heat pump, an abnormality such as an overload operation or a gas phase inflow operation during operation by using the rotation speed of the gear solution pump. The present invention relates to a method for controlling a solution pump of an ammonia absorption heat pump that can detect and control state operation.

In general, the ammonia absorption heat pump includes a regenerator 1, a rectifier 2, a condenser 3, a supercooler 4, an evaporator 5, and a water cooling absorber 6, as shown in FIG. and a heat exchanger composed of a cooled absorber and a solution cooled absorber 7, a solution pump 8, a solution tank 9, a burner 10, and the like.

Hereinafter, the operation of the heat pump having the above configuration will be described.

The regenerator 1 serves to separate ammonia, which is a refrigerant, and when the burner 10 is heated, boiling occurs, resulting in a solution having a low ammonia concentration (hereinafter referred to as a chemical solution) and a low concentration refrigerant. Steam will be generated.

Subsequently, the generated refrigerant vapor rises and flows into the rectifier (2; rectifier), and the chemical solution flows into the upper end portion of the solution cooling absorber (7), which is a low pressure part, through an expansion device (12).

On the other hand, the refrigerant vapor in the rectifier (2) is rectified in a high concentration by the condensation heat transfer phenomenon by the low temperature steel solution flowing inside the condenser (3), and condensed by the cooling water in the condenser (3) to the liquid refrigerant do.

Subsequently, the liquid refrigerant of the condenser 3 is further subcooled in the subcooler 4 and flows out. The liquid refrigerant is introduced into the evaporator 5 through the expansion valve 11 and the refrigerant is abnormal by heat exchange with chilled water 15 ( boiling in two phases, the cold water temperature is lowered to obtain a cooling load.

The coolant of the ideal flow flowing out of the evaporator 5 flows back into the subcooler 4, and heats with a relatively high temperature liquid refrigerant in the subcooler 4 to further boil it, thereby lowering the bottom of the water cooling absorber 6. Flows into.

The refrigerant vapor introduced into the water cooling absorber 6 is mixed with the medicinal solution introduced into the upper end of the solution cooling absorber 7 to generate an absorption phenomenon, thereby generating a strong solution at the lower end of the water cooling absorber 6. At this time, the generated heat of absorption is removed by the cooling solution 14 of the water cooling absorber 6 and the strong solution flowing inside the solution cooling absorber 7.

The liquid solution at the outlet of the lower end of the water cooling absorber 6 is separated from the liquid tank 9 by the liquid solution, and then boosted by the solution pump 8 to pass through the rectifier 2 and the solution cooling absorber 7. The temperature rises and flows into the regenerator 1, and the above process is repeated.

However, when the solution pump 8 is a gear-type pump in the ammonia absorption heat pump having the above-described configuration and operation, when the gaseous phase flows into the solution pump 8, the wear of the gear proceeds and the performance of the pump is deteriorated. If the differential pressure at both ends of the pump exceeds the maximum pressure, the motor may be overheated.

Therefore, in order to solve the above problems, the size of the solution tank 9 at the pump inlet is sufficiently large so that a predetermined amount or more of the solution is always retained in the solution tank 9 during operation of the solution pump 8. The solution was introduced into the solution pump 8 or a method of controlling the pump to always be at a constant level by attaching a water level sensor to detect the water level in the solution tank 8.

However, when forming a large volume of the solution tank 9 as described above, there is a problem that the size of the entire heat pump system is increased and the solution filling amount is increased.

In addition, in the case of attaching the water level sensor in the solution pump 8, the sensor must be installed in the high pressure tank and a signal must be transmitted to the outside of the pump, which may cause problems in the sealing of the pump and maintaining the internal pressure. Due to this, it is difficult to select the material of the sensor, and in particular, there may be a problem in durability when there is a moving part. In addition, when a float occurs due to corrosion of the aqueous ammonia solution, there is a problem that the water level sensor may malfunction due to the float and affect the pump.

Therefore, the present invention has been made to solve the above problems, does not increase the size of the entire system, and the abnormality due to gas phase inflow and overload in the solution pump without installing additional devices inside the solution pump, such as sensors It is an object of the present invention to provide a method for controlling a solution pump of an ammonia absorption heat pump that can detect a state operation and protect the solution pump.

1 is a configuration diagram showing the configuration and operation of a general ammonia absorption heat pump

Figure 2a is a graph showing the relationship between the solution discharge amount and the pump pressure difference between the pump and the motor speed of the solution pump

Figure 2b is a graph showing the relationship between the motor speed of the solution pump, the differential pressure across the pump and the motor input voltage

Figure 3 is a flow chart showing a solution pump control method according to the present invention

Description of the main parts of the drawings

S1-steady state voltage input stage S2-measuring stage

S3-Comparison judgment stage S4-Adjustment stage

S5-Second measurement step S6-Second comparison judgment step

S7-Control step S8-Restart step

In order to achieve the above object, the control method of the present invention is operated by applying an input voltage according to a steady state operating condition to a solution pump, and then measuring the number of rotations of the motor in operation and comparing it with the input motor speed. By determining whether the measured speed of the motor is within the range of the motor speed of the steady state operation inputted in advance, and detecting whether the solution pump is in the steady state operation or the abnormal state operation caused by meteorological inflow or overload. To control accordingly.

Hereinafter, an embodiment of a control method according to the present invention will be described in detail with reference to the accompanying drawings.

First, the control method according to the present invention detects and controls the steady state operation and the abnormal state operation using the motor rotational speed, and obtains the steady state operating conditions by the following operating characteristics of the gear-type solution pump.

As shown in FIG. 2A, the solution discharge amount of the solution pump decreases as the pressure difference across the pump increases, and the solution discharge amount and the pressure difference across the pump increase respectively when the motor rotation speed increases.

Therefore, the relationship between the differential pressure and the discharge amount according to the respective rotation speeds in the pump operating range can be experimentally obtained by the above relationship. At this time, in a properly designed gear type pump, the influence of the solution viscosity is not large and the average value of the operating range may be used as a representative value.

In addition, the rotational speed of a general motor is controlled by the motor input voltage, and the rotational speed of the motor and the differential pressure across the pump according to the motor input voltage are rotated at the same input voltage as the differential pressure across the pump increases as shown in FIG. 2B. When the input voltage of the motor increases, the motor speed and the differential pressure between the pumps increase. This relationship can also be obtained through experiments.

Therefore, it is possible to obtain a steady state operating condition and an input voltage value at this time by the above relationships, and the steady state operating condition and input voltage provide a criterion for determining an abnormal state operation in the control method of the present invention. do.

That is, when the gaseous phase flows into the pump, the motor speed rises above the motor speed under the above-mentioned steady state operating condition, and when the solution pump is overloaded, the speed of the motor falls below the motor speed under the above-mentioned steady state operating condition. Since it is reduced, it is to determine and control the state of the solution pump according to each motor speed.

On the other hand, Figure 3 is a flow chart showing a solution pump control method according to the present invention, the control method of the present invention, the steady-state voltage input step (S1) and operating the solution pump by applying an input voltage according to the steady-state operating conditions and The measuring step (S2) of measuring the rotational speed of the motor in operation, the rotational speed of the motor measured in the measuring step (S2) and the motor rotational speed at the steady state input voltage input in the voltage input step (S1) Compared to, and comparing with the determination step (S3) for determining whether the measured motor speed is within the minimum and maximum speed range of the input voltage, and continues to operate according to the motor speed determined by the comparison, Adjusting the input voltage of the solution pump, or adjusting the step (S4) to operate the motor at the minimum speed, and the second measurement to re-measure the rotational speed of the motor after a certain time after the adjustment step (S4) only (S5) and the motor speed measured by comparing the actual motor speed measured in the second measurement step (S5) and the motor speed at the steady state input voltage, the minimum and maximum speed at the input voltage Control step of controlling to maintain the steady state operation or stop the motor according to the second comparison determination step (S6) to determine whether it is within the range and the rotation speed determined in the second comparison determination step (S6) ( S7) and restarting step (S8) for restarting the solution pump after a predetermined time when the motor is stopped in the control step (S7) is made sequentially.

In the steady state voltage input step S1, an input voltage required for the steady state operation is applied to the solution pump according to the steady state operating condition and the input voltage obtained by the operating characteristics described with reference to FIGS. 2A and 2B.

In addition, in the comparison determination step (S3) by comparing the measured motor rotation speed with the motor rotation speed at the input voltage, it is determined whether the solution pump is in a steady state operation or an abnormal state operation. In order to accurately determine the accuracy of the motor, a database on the motor rotation speed is required, and since the normal operation data is usually included in the operation algorithm of the air conditioner, the existing data can be used without any additional input. Can be.

And, in the adjusting step (S4) to adjust the operation of the solution pump in accordance with the determination in the comparison determination step (S3), if the measured motor speed is within the range of the motor speed at the input voltage of the solution pump The operation proceeds as it is without the need to adjust the operation, and if the measured motor speed is less than the minimum motor speed at the input voltage, it is determined that the pump is overloaded, so the solution pump operation is adjusted to increase the input voltage. If the measured motor speed is greater than the maximum motor speed at the input voltage, it is determined that gas phase inflow has occurred in the solution pump. Will be adjusted to obtain data.

Then, when it is determined that the abnormal state operation in the comparison determination step (S3) and the operation of the solution pump is adjusted through the adjustment step (S4), after the predetermined time has elapsed again measures the rotational speed of the motor, Compared with the motor rotation speed, when the steady state operating condition is not restored and the abnormal state operating condition occurs, the operation of the solution pump is stopped in the control step S7.

At this time, it is preferable to provide a check valve at the pump discharge port to prevent the solution from flowing back from the high pressure portion.

As the abnormal state operation occurs as described above, the solution pump is stopped and restarted after a certain time. If a check valve is not installed at the pump outlet, the solution or gas of the high pressure part is directed to the absorber side. Wait until the pump is able to start because the backflow of the pump is reduced below a certain level and must be restarted.

As described above, according to the present invention, it is possible to detect and control the abnormal operation of the solution pump by using the rotational speed of the motor, so as to increase the volume of the solution tank, the size and weight of the system and the amount of solution filling It is possible to ensure the stability of the solution pump without increasing or mounting a level sensor in the solution pump.

Claims (1)

A normal operation state voltage input step of operating a solution pump by applying an input voltage according to a steady state operation condition; A measurement step of measuring a rotation speed of a motor in operation while driving the solution pump; Comparison of judging whether the measured motor speed is within the minimum speed and maximum speed range of the input voltage by comparing the speed of the motor measured in the measuring step with the speed of the motor at the steady state input voltage. Judgment phase, When the rotation speed measured in the comparison determination step is determined to be a value within the range of the motor rotation speed at the steady state input voltage, it is determined that the steady state operation is continued and the measured rotation speed is greater than or equal to the maximum rotation speed at the input voltage. If it is determined that the weather has flowed in, the motor is operated at the minimum speed, and if it is determined that the measured speed has a value less than the minimum speed at the input voltage, it is determined to be overloaded and the input voltage is increased. To make adjustments, A second measurement step of re-measuring the rotational speed of the motor after a predetermined time elapses after the adjusting step; The second step of determining whether the measured motor speed is within the minimum and maximum speed range of the input voltage by comparing the actual speed of the motor measured in the second measurement step with the speed of the motor in the steady state operation. Comparison judgment step, If it is determined that the motor speed measured in the second comparison determination step is within the reference motor speed range, the motor continues to operate in a steady state, and if the determined speed is not within the speed range of the steady state operation, the motor is stopped. A control step to control the Solution pump control method of the ammonia absorption heat pump made of a restart step of restarting the solution pump after a predetermined time when the motor is stopped in the control step.