JP2007240131A - Optimization control of heat source unit and accessory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for refrigerating machines and accessories that can save total energy for heat source units, hot/cold water pumps (including cold water pumps) and, in the case of a water-cooled system, cooling tower fans. <P>SOLUTION: A current value 10, a differential pressure 9 and a hot/cold water outlet temperature 8 of each heat source unit 1, and a (supply) header temperature 12 are measured and a heat source unit load factor is computed to determine a heat source unit margin, and multiunit control is applied according to the (supply) header temperature and load factor. A minimum flow rate is ensured according to the differential pressure, and a hot/cold water pump is inverter-controlled according to the load factor and (supply) header temperature. If the heat source unit has an external hot/cold water outlet temperature setting function, the hot/cold water outlet temperature setting is automatically corrected at an individual operation. An outside air temperature/humidity sensor computes an outside air wet bulb temperature, and a cooling water temperature setting is automatically changed to control a cooling tower fan. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for controlling the number of heat source devices and an inverter control method for auxiliary devices.

  As an air conditioning system using a heat source machine (including air-cooled chillers, air-cooled heat pumps, and various water-cooled chillers), a cold / hot water piping system (including only cold water) and a cooling water piping system are connected to the heat source machine, and the cold / hot water piping system is cooled Connect the water pump (including the chilled water pump), the bypass piping between the headers and multiple secondary equipment to circulate cold / hot water (including chilled water), and connect the cooling water pump and cooling tower to the cooling water piping. Air conditioning systems that circulate cooling water are generally used.

  It is important how these devices with large power consumption can be saved. Regarding the number control method, conventionally, the approximate load is calculated based on the secondary flow rate, the water supply temperature, and the return temperature, and the heat source unit is set with a fixed specification capacity, and it is set with a margin for possible load calculation errors. The number of heat source units is controlled according to the load value, and the factors that the capacity of the heat source unit fluctuates due to the outside air wet bulb temperature, dirt, leaks, etc. are ignored. There is a lot of driving and wasteful energy is used.

  Looking at the control method for cold / hot water pumps, inverters are often not used in the past, and fixed operation is possible even if inverters are used, and power that can be reduced depending on the state of the heat source and load is wasted. is doing.

  As for the cooling tower fan control method, conventionally, the cooling tower outlet temperature is started and stopped by a fixed set value, and depending on the outside air wet bulb temperature, electric power that can reduce the power consumption of the heat source unit is wasted.

  The present invention takes into account the heat source unit state and the outside air wet bulb temperature state, and performs control to reduce energy consumption in total with the heat source unit, cold / hot water pump, cooling water pump, cooling tower fan, and control to reduce wasted power The purpose is to provide a method.

  In order to achieve such an object, the configuration of the present invention is as follows.

  (1) Input the current value of each heat source unit and the measured value of the secondary side water supply temperature, and increase the stage when the capacity of the operating heat source unit becomes the limit and the water supply temperature exceeds the set value for a certain period of time, Decrease the stage when the capacity is maintained even if the stage is reduced, and the stage is reduced, and when one unit is operating, the hot / cold water outlet temperature setting and header (outward) temperature setting are automatically set according to the decrease in the number of chilled water pump rotations. Control method to be corrected.

  (2) Enter the measured values of the hot / cold water inlet / outlet temperature and the hot / cold water inlet / outlet pressure (including differential pressure) of each heat source unit, and secure the minimum required flow rate so that the header (outward) temperature is the set temperature. A control method that controls the rotational speed with an inverter.

  (3) Input the measured values of the outlet temperature of each cooling tower and outside air temperature humidity (including the outside air wet bulb temperature), automatically change the cooling water temperature setting to an appropriate value, and control the cooling tower fan to start / stop or inverter Control method to control.

  (1) The power of auxiliary pumps and fans that have been operating because the heat source equipment has been operating in excess can be reduced.

  (2) Electric power of the chilled / hot water pump can be reduced by reducing unnecessary chilled / hot water flow rate at start-up and securing a flow rate as required.

  (3) By reducing the cooling water temperature when it is lowered, the compression load of the heat source device can be reduced, and the power or gas of the heat source device can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a system configuration diagram showing an embodiment of a system around a heat source apparatus according to the present invention. This system includes a cold / hot water piping system 2 and a cooling water piping system 3 connected to the heat source unit 1. The cold / hot water piping system 2 is provided with a cold / hot water pump 6. The cooling water piping system 3 is provided with a cooling water pump 7 and a cooling tower 14.

  The heat source device 1 is provided with an ammeter 10. In order to measure the differential pressure at the inlet / outlet of the chilled / hot water of the heat source unit 1, the chilled / hot water pipe 2 is provided with a pressure transmitter 9 (including a differential pressure transmitter) and a temperature sensor 8 on the chilled / hot water outlet side.

The cold / hot water pump 6 is provided with an inverter 11. The header 4 is provided with a temperature sensor 12. The header (return) 5 is provided with a temperature sensor 13.

  The cooling tower 14 is provided with an inverter 15. A temperature sensor 16 is provided in the cooling water system pipe 3 on the outlet side of the cooling tower 14. An outside air temperature / humidity sensor 17 (including an outside air dew point temperature sensor and an outside air enthalpy sensor) is provided in order to calculate the outside air wet bulb temperature from the outside air temperature humidity.

  The above data is taken into the control device 18 and controlled.

  Looking at the heat source machine main body, the main body control is usually performed so that the outlet temperature of the cold / hot water becomes a set value and the current does not exceed the rated value. In the case of cold water, if the cold water inlet temperature is low when the cold water flow rate is constant, the heat source machine body performs capacity control. On the other hand, when the cold water inlet temperature is high and the heat source function is full, the cold water outlet temperature rises.

  Further, as a characteristic of the heat source unit, there is a characteristic that not only the efficiency is improved when the cooling water temperature is lowered (in the case of an air-cooled chiller, the temperature of the outside wet bulb is lowered), but the refrigeration capacity is also improved.

  FIG. 2 is a functional block diagram of the heat source unit number control method. Utilizing the above characteristics of the heat source machine, determine whether there is sufficient heat source functional capacity based on the operating current value and rated current, and if the heat source machine is a turbo chiller, determine whether the vane opening is also fully open In addition, it is judged whether it is necessary to increase from the header (outward) temperature and current load. The step-down is determined based on the load factor obtained by dividing the total current load factor of the operating heat source unit by the number of operating units minus 1 and the header (outward) temperature. As a result, there is no need to turn a heat source machine or its auxiliary equipment (cold / hot water pump, cooling water pump, cooling tower fan) wastefully. When one heat source unit is operating, the cold / hot water outlet temperature setting and header (outward) temperature setting are automatically corrected within the upper and lower limits in proportion to the number of rotations of the cold / hot water pump. Thereby, at the time of low load, the operating power of the heat source machine is reduced, and energy saving can be performed.

  FIG. 3 is a functional block diagram of the inverter control method for the cold / hot water pump. Regarding the cold / hot water pump, it can be said that it is sufficient to ensure the minimum required flow rate and to satisfy the cold / hot water outlet temperature so that the heat source machine does not freeze. The minimum required flow rate of the heat source machine can be judged by the minimum required differential pressure. In the case of cold water, the amount of uncooled water sent to the secondary side can be minimized by performing inverter control of the cold / hot water pump so as to maintain the minimum differential pressure when starting the heat source machine. In the case of cold water, the inverter control is performed so that the number of revolutions is increased when the header (outward) temperature rises and the heat source functional power is sufficient, and the temperature decreases when the header (outward) temperature is kept at the set value. Do. As a result, if the header (return) temperature falls and the heat source machine has sufficient power, the cold / hot water outlet temperature and the header (outward) temperature fall, and the inverter speed decreases. When the header (return) temperature rises and the load cannot meet the load, the header (outward) temperature rises, so if the heat source machine has enough power, the inverter rotation speed is increased. When there is no more power in the heat source machine, the number of stages is increased by the above-mentioned number control, so that energy saving of the chilled / hot water pump can be achieved without causing any problem in the capacity.

  FIG. 4 is a functional block diagram of the cooling tower fan control method. Looking at the cooling water system, if the cooling water temperature decreases, the efficiency of the heat source equipment will improve and the capacity will also be improved, calculating the outdoor wet bulb temperature and setting the cooling water temperature setting value that can be lowered by the cooling tower Calculate. At this time, the minimum cooling water temperature of the heat source unit is maintained. The start / stop control of the cooling tower fan or the inverter control is performed so that the set value is obtained. If there is a bypass valve, it should only be used as a safety measure to prevent the temperature from falling below the minimum temperature. The inverter of the cooling water pump needs to flow an appropriate amount so that silica or the like does not easily adhere to the tube. Decreasing the heat conductivity of the tube will reduce the efficiency of the refrigerator, but the pump selected by design usually has a capacity larger than the specification, so that the power can be reduced. As a result, meaningless fan operation exceeding the cooling tower capacity can be eliminated, and when the cooling water temperature can be further lowered, the efficiency and capacity of the heat source apparatus can be increased.

  1 is a system configuration diagram showing an embodiment of a system around a heat source device according to the present invention.   Functional block diagram of heat source unit control method   Functional block diagram of inverter control method for cold / hot water pump   Functional block diagram of cooling tower fan control method

Explanation of symbols

1 Heat source machine 2 Cold / hot water piping system 3 Cooling water piping system 4 Header (outward)
5 Header (Return)
6 Chilled / hot water pump 7 Chilled water pump 8 Heat source machine chilled / hot water outlet hot water sensor 9 Heat source machine chilled / hot water pressure (differential pressure) transmitter 10 Heat source machine current sensor 11 Chilled / hot water pump inverter 12 Header (outward) temperature sensor 13 Header (return) ) Temperature sensor 14 Cooling tower 15 Cooling tower fan inverter 16 Cooling tower outlet temperature sensor 17 Outside air temperature humidity (wet bulb temperature) sensor 18 Controller

Claims (3)

  As an air conditioning system that uses heat source equipment (including air-cooled chillers, air-cooled heat pumps, and various water-cooled chillers), a cold / hot water piping system (including only cold water) is connected to the heat source equipment, and a cold / hot water pump (cold water pump) is connected to the cold / hot water piping system. In the air conditioning system that circulates cold / hot water (including chilled water) by connecting bypass piping between headers and multiple secondary equipments, the load factor of the heat source is determined by the current value, and the header (outward) temperature and A control method in which the number of units is controlled by the load factor, and when the heat source device has an external cold / hot water outlet temperature setting function, the cold / hot water temperature setting is automatically corrected when one unit is in operation.   A control method for detecting a differential pressure of cold / hot water flowing through the heat source unit and controlling an inverter of the cold / hot water pump according to the load factor, the header (outward) temperature, and the cold / hot water outlet temperature if the flow rate exceeds the required minimum flow rate.   In the above heat source unit, a cooling water piping system is connected, a cooling water pump and a cooling tower are connected to the cooling water piping system, and the cooling water is circulated. A control method for controlling the tower fan.

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