Refrigerating machine exhaust pressure control system

Abstract

The utility model belongs to the technical field of automatic control of refrigerating machines, and particularly relates to an exhaust pressure control system of a refrigerating machine. The system comprises at least one group of evaporative condensers, the evaporative condensers are provided with two circulating water pumps and at least three fans, and the evaporative condensers are connected with an air suction pipeline and a liquid supply pipeline; the frequency converter is used for adjusting operation frequencies of the circulating water pump and the fan; the pressure transmitter is used for measuring the pressure of the liquid supply pipeline; and the control unit is used for receiving the measurement data of the pressure transmitter, controlling the starting and stopping numbers of the circulating water pumps and the fans according to the measurement data, and controlling the frequency converter to correspondingly adjust the operation frequencies of the circulating water pumps and the fans. The technical problems that in the prior art, due to the fact that exhaust pressure of a refrigerating machine which conducts condensation through an evaporative condenser unit is unstable, the refrigerating machine runs unstably, and energy consumption is high are solved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of refrigeration machine automatic control, more particularly, relate to a refrigeration machine exhaust pressure control system. BACKGROUND

[0002] In large refrigeration system, evaporative condenser is connected with refrigeration machine, and the evaporative condenser utilizes the spray water outside the coil to evaporate and absorb the heat of high-temperature gaseous refrigerant in the coil to gradually cool the refrigerant in the coil from gaseous state to liquid state. Influenced by the external environment temperature, water temperature and refrigeration machine load, the condensing speed or condensing effect of the evaporative condenser directly affects the size of the refrigeration machine exhaust pressure. Specifically, if the evaporative condenser has poor condensing effect, the exhaust pressure will increase, and the energy consumption of the refrigeration machine will increase significantly. The excessively high exhaust pressure is easy to cause the refrigeration machine to overload and shut down. If the evaporative condenser is over-condensed, the exhaust pressure is too low, which is easy to cause the refrigeration machine to run with liquid, further causing the refrigeration machine to shut down. Therefore, according to the production process requirements, it is necessary to stably control the exhaust pressure of the refrigeration machine, and at the same time, the refrigeration machine can run more stably and achieve economic and energy-saving operation.

[0003] Chinese patent document CN110617732A discloses a two-stage spraying device for an evaporative condenser, which comprises a spraying coil installed on the top of the evaporative condenser, a humidity sensor installed at the outlet of the evaporative condenser, an exhaust temperature sensor installed on the compressor exhaust pipe, a high-pressure pressure transmitter connected with the compressor exhaust pipe, and a controller. The spraying coil is connected with a water storage tank through a spraying electromagnetic valve and a spraying water pump. The opening and closing of the spraying electromagnetic valve and the spraying water pump are controlled by the controller, and the number of evaporative condenser fans that are turned on is also controlled by the controller. The device can be widely applied to cold storage refrigeration systems, and can play a role in energy saving and cost reduction by controlling the number of evaporative condenser fans that are turned on.

[0004] In addition, Chinese patent document CN102997510A discloses an evaporative condenser, a refrigeration and air conditioning unit applying the evaporative condenser, and a control method thereof. The method controls the start of the evaporative condenser, the fan and the water pump of the evaporative condenser according to the environmental temperature, adjusts and controls the working state of the evaporative condenser, the fan and the water pump according to the environmental temperature and the exhaust pressure value of the compressor, so as to maintain the exhaust pressure of the compressor within a preset pressure value range, minimize the operating power of the fan and the water pump, and dynamically match the heat dissipation capacity of the evaporative condenser with the heat dissipation amount required when the compressor is running.

[0005] Therefore, it is urgent to design an automatic control system for stably controlling the exhaust pressure of a refrigeration machine and a plurality of series-connected evaporative condenser water pumps and fans, so as to solve the problem of unstable exhaust pressure of the refrigeration machine that is condensed by the evaporative condenser unit, and to solve the problems of unstable operation and high energy consumption of the refrigeration machine. UTILITY MODEL CONTENTS

[0006] The utility model aims at overcoming at least one of the above prior art defects, provides a refrigeration machine exhaust pressure control system to solve the technical problem of unstable refrigeration machine exhaust pressure of the evaporative condenser unit, which leads to unstable operation of the refrigeration machine and high energy consumption.

[0007] The detailed technical scheme of the utility model is as follows:

[0008] A refrigeration machine exhaust pressure control system, the system comprises:

[0009] At least one set of evaporative condensers, the evaporative condenser is provided with two circulating water pumps and at least three fans, and the evaporative condenser is connected with a suction pipeline and a liquid supply pipeline;

[0010] A frequency converter is electrically connected to the circulating water pump and the fan of the evaporative condenser, and is used for adjusting the operating frequency of the circulating water pump and the fan;

[0011] A pressure transmitter is installed at one end of the liquid supply pipeline close to the evaporative condenser, and is used for measuring the pressure of the liquid supply pipeline; and a control unit is electrically connected to the circulating water pump, the fan of the evaporative condenser, the frequency converter and the pressure transmitter, respectively, the control unit is used for receiving the measurement data of the pressure transmitter, and controlling the start-stop number of the circulating water pump and the fan according to the measurement data, and controlling the frequency converter to adjust the operating frequency of the circulating water pump and the fan.

[0012] According to the utility model, preferably, the frequency converter comprises a circulating water pump frequency converter and a fan frequency converter, the circulating water pump frequency converter is electrically connected to the circulating water pump of the evaporative condenser, and is used for adjusting the operating frequency of the circulating water pump; the fan frequency converter is electrically connected to the fan of the evaporative condenser, and is used for adjusting the operating frequency of the fan.

[0013] According to the utility model, preferably, among the two circulating water pumps of the evaporative condenser, one circulating water pump is a normally open circulating water pump, and the other circulating water pump is a standby circulating water pump.

[0014] According to the utility model, preferably, the number of the circulating water pump frequency converter is at least one, which is used for adjusting the operating frequency of the normally open circulating water pump.

[0015] According to the utility model, preferably, the number of the fan frequency converter is at least one, which is used for adjusting the operating frequency of one fan of the evaporative condenser.

[0016] According to the utility model, preferably, each circulating water pump and each fan of the evaporative condenser has a control end separate start-stop function.

[0017] According to the preferred embodiment of the present application, the system further comprises a compressor, which is installed on the suction pipeline and used for compressing gaseous refrigerant, and the compressed gaseous refrigerant passes through the evaporative condenser.

[0018] According to the preferred embodiment of the present application, the system further comprises a liquid storage tank, which is installed on the liquid supply pipeline at a position close to the outlet of the liquid supply pipeline and used for storing liquid-phase refrigerant obtained by condensation of the evaporative condenser.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The refrigeration machine exhaust pressure control system provided by the present application measures the pressure on the liquid supply pipeline, i.e., the refrigerant outlet main pipeline of the evaporative condenser, by means of the pressure transmitter, and transmits the measurement data to the control unit, which generates corresponding control instructions according to the measurement data to control the start-stop number of the circulating water pump and the fan and to control the frequency converter to adjust the operating frequency of the circulating water pump and the fan, thereby achieving automatic control of the refrigeration machine exhaust pressure and the circulating water pump and the fan of the multiple series-connected evaporative condensers. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural schematic diagram of the refrigeration machine exhaust pressure control system of the present application.

[0022] In the figure: 1-first evaporative condenser, 2-second evaporative condenser, 3-third evaporative condenser, 4-control unit, 5-compressor, 6-liquid storage tank. DETAILED DESCRIPTION

[0023] The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs.

[0025] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit exemplary embodiments according to the present disclosure. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0026] The embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0027] The refrigeration machine exhaust pressure control system of the utility model can realize the automatic control of the refrigeration machine exhaust pressure and the circulating water pump and the fan of the multiple series evaporative condensers, and can realize the stable control of the refrigeration machine exhaust pressure and the reduction of the refrigeration machine energy consumption.

[0028] The refrigeration machine exhaust pressure control system of the utility model will be further described in combination with specific embodiments.

[0029] Embodiment 1,

[0030] The refrigeration machine exhaust pressure control system of the utility model will be further described in combination with specific embodiments. Figure 1 As shown in the figure, the system comprises at least one group of evaporative condensers and a frequency converter and a pressure transmitter PT01 arranged correspondingly with the evaporative condensers, wherein the evaporative condensers are provided with two circulating water pumps and at least three fans, the two circulating water pumps have the function of one active and one standby, and each circulating water pump and fan can be individually controlled; meanwhile, the evaporative condensers are also connected with a suction pipeline and a liquid supply pipeline, and the evaporative condensers are used for condensing gaseous refrigerant into liquid phase refrigerant.

[0031] The frequency converter is electrically connected with the circulating water pump and the fan of the evaporative condenser, is used for adjusting the operating frequency of the circulating water pump and the fan according to the control requirement, and the frequency converter has a DCS remote adjustment function.

[0032] The pressure transmitter PT01 is installed at one end of the liquid supply pipeline connected with the refrigerant outlet of the evaporative condenser close to the evaporative condenser, is used for measuring the pressure of the liquid phase refrigerant flowing into the liquid supply pipeline after the gaseous refrigerant is condensed by the evaporative condenser, that is, the exhaust pressure.

[0033] The system further comprises a control unit 4, the control unit 4 is electrically connected with the circulating water pump, the fan, the frequency converter and the pressure transmitter PT01 of the evaporative condenser respectively, is used for receiving the measurement data of the pressure transmitter PT01, and according to the measurement data, the start-stop number of the circulating water pump and the fan is controlled, and the operating frequency of the circulating water pump and the fan is adjusted correspondingly by the frequency converter, so as to achieve the purpose of stably controlling the outlet exhaust pressure of the evaporative condenser.

[0034] In this embodiment, the control unit 4 can adopt a DCS (Distributed Control System) system, which has PID operation and control functions, and is convenient for pressure and frequency converter control, historical trend query, alarm intervention, etc. The control program executed by the control unit belongs to the conventional setting in the field and can be implemented by those skilled in the art, and does not belong to the improvement of the system, which will not be described here.

[0035] In actual work, the evaporative condenser is generally provided with multiple groups, and the multiple groups of evaporative condensers are operated at the same time. In this embodiment, three groups of evaporative condensers are provided, which are a first evaporative condenser 1 (1# evaporative condenser), a second evaporative condenser 2 (2# evaporative condenser), and a third evaporative condenser 3 (3# evaporative condenser). The three groups of evaporative condensers are arranged in series in structure and are operated in parallel in work. When a single group of evaporative condensers is overhauled, the evaporative condenser under overhaul can be switched out through a valve, and the equipment state in the DCS system is set to an overhauling state. When the overhauling state, all circulating water pumps and fans of the evaporative condenser are automatically switched to the overhauling state and do not participate in the automatic control program control.

[0036] The first evaporative condenser 1, the second evaporative condenser 2, and the third evaporative condenser 3 are each provided with two circulating water pumps, and one of the two circulating water pumps is a normally open circulating water pump, and the other is a standby circulating water pump, that is, it has one open and one standby function. In this embodiment, the circulating water pumps provided for the three groups of evaporative condensers are P1A-P3A and P1B-P3B, wherein P1A-P3A are the normally open circulating water pumps of the three groups of evaporative condensers, and P1B-P3B are the standby circulating water pumps of the three groups of evaporative condensers.

[0037] The first evaporative condenser 1, the second evaporative condenser 2, and the third evaporative condenser 3 are each provided with three fans for circulating water cooling. In this embodiment, the fans provided for the three groups of evaporative condensers are F1A / B / C-F3A / B / C.

[0038] It should be understood that each circulating water pump and each fan in each group of evaporative condensers has a control end start-stop function, that is, each circulating water pump and each fan can be controlled individually by the DCS system.

[0039] Further, the frequency converter in the embodiment includes a circulating water pump frequency converter BP and a fan frequency converter BF. The circulating water pump frequency converter BP is electrically connected with the circulating water pump of the evaporative condenser, and is used to adjust the operating frequency of the circulating water pump. The fan frequency converter BF is electrically connected with the fan of the evaporative condenser, and is used to adjust the operating frequency of the fan, i.e. to adjust the rotating speed of the cooling fan of the evaporative condenser. The circulating water pump frequency converter BP and the fan frequency converter BF can both realize remote control function of the DCS system.

[0040] It should be understood that, in the three groups of evaporative condensers in the embodiment, the always-on circulating water pump as the main machine has the function of frequency adjustment, and at least one fan also has the function of frequency adjustment. Therefore, the number of the circulating water pump frequency converter and the fan frequency converter in the embodiment is at least one, for example, the circulating water pump frequency converter BP1 and the fan frequency converter BF1, respectively, are used to adjust the operating frequency of the always-on circulating water pump and the operating frequency of one of the fans.

[0041] Preferably, a plurality of groups of circulating water pump frequency converters and fan frequency converters can be provided according to the number of all circulating water pumps and fans in each evaporative condenser, so that each circulating water pump and each fan in each group of evaporative condensers can realize the function of frequency adjustment.

[0042] In the embodiment, the system further includes a compressor 5 and a liquid storage tank 6. The compressor 5 is installed on the suction pipeline connected with the evaporative condenser, and is used to compress the gaseous refrigerant. The compressed gaseous refrigerant passes through the evaporative condenser. The liquid storage tank 6 is installed on the liquid supply pipeline connected with the evaporative condenser, and is located at one end of the liquid supply pipeline close to the outlet thereof, specifically between the outlet of the liquid supply pipeline and the pressure transmitter PT01, and is used to store the liquid-phase refrigerant obtained by condensation of the evaporative condenser.

[0043] It should be understood that, as a background control system, the DCS system has corresponding buttons to facilitate the operation of the operator. For example, the evaporative condenser maintenance / standby state selection button is set. When the 1#, 2# and 3# evaporative condensers are all in the "maintenance" state, the circulating water pump and the fan of the evaporative condenser do not participate in the automatic program control. When the 1#, 2# and 3# evaporative condensers are all in the "standby" state, the corresponding circulating water pump and fan can be started according to the program setting.

[0044] The circulating water pump frequency conversion and the fan frequency conversion of the evaporative condenser can be automatically adjusted according to the refrigeration machine exhaust pressure set value. The refrigeration machine exhaust pressure set value can include a high limit set value PT01 H and a low limit set value PT01 L. The specific adjustment process is as follows:

[0045] Case 1: When the refrigeration machine exhaust pressure (i.e. the data measured by pressure transmitter PT01) is higher than the high limit set value PT01 H, the circulating water pump of the next evaporative condenser is started in sequence, and the circulating water pump frequency converter enters the pressure-frequency PID automatic adjustment mode;

[0046] When the circulating water pump frequency converter is running at full frequency, if the exhaust pressure is still higher than the high limit set value PT01 H, the fan B of the evaporative condenser is started, and the fan B frequency converter enters the pressure-frequency PID automatic adjustment mode, while the circulating water pump keeps running at full frequency;

[0047] When the fan B is running at full frequency, if the exhaust pressure is still higher than the high limit set value PT01 H, the fan A is started at constant frequency, and the fan B frequency converter enters the pressure-frequency PID automatic adjustment mode;

[0048] If the exhaust pressure is still higher than the high limit set value PT01 H, the fan C is started at constant frequency, and the fan B frequency converter enters the pressure-frequency PID automatic adjustment mode;

[0049] If the exhaust pressure is still higher than the high limit set value PT01 H, the next standby evaporative condenser is started; the fan frequency converter is always in the pressure-frequency PID automatic adjustment mode during operation; and the other evaporative condensers enter the running state in sequence according to the above steps.

[0050] Case 2: When the refrigeration machine exhaust pressure is lower than the low limit set value PT01 L, and the frequency of the fan B of the last evaporative condenser is lower than 20 Hz, the fan C at constant frequency is stopped;

[0051] If the refrigeration machine exhaust pressure is still lower than the low limit set value PT01 L, and the frequency of the fan B is still lower than 20 Hz, the fan A at constant frequency is stopped;

[0052] If the refrigeration machine exhaust pressure is still lower than the low limit set value PT01 L, and the frequency of the fan B is still lower than 20 Hz, the fan B frequency converter is stopped, and the circulating water pump enters the pressure-frequency PID automatic adjustment mode;

[0053] When the circulating water pump frequency is lower than 30 Hz, and the refrigeration machine exhaust pressure is still lower than the low limit set value PT01 L, the circulating water pump is stopped, the evaporative condenser exits the running state and enters the standby state, and the other evaporative condensers are sequentially stopped in sequence.

[0054] In actual operation, the running control pressure, the low limit pressure and the high limit pressure of the refrigeration machine exhaust pressure can be set by the operator according to the weather and the refrigeration machine load.

[0055] Therefore, the refrigerating machine exhaust pressure control system of the embodiment not only realizes the automatic control of the refrigerating machine exhaust pressure and the circulating water pump and the fan of the multiple series evaporative condensers, but also realizes the stable control of the refrigerating machine exhaust pressure and the reduction of the refrigerating machine energy consumption.

[0056] Obviously, the above embodiments of the utility model are only examples for clearly illustrating the technical scheme of the utility model, and are not a limitation on the specific embodiments of the utility model. Any modification, equivalent replacement and improvement made within the spirit and principle of the utility model claim should be included in the protection scope of the utility model claim.

Claims

1. A chiller exhaust pressure control system characterized by, The system comprises: at least one set of evaporative condensers, which are configured with two circulating water pumps and at least three fans, and are connected with suction pipelines and liquid supply pipelines; a frequency converter, which is electrically connected with the circulating water pumps and the fans of the evaporative condensers, and is used for adjusting the operating frequencies of the circulating water pumps and the fans; a pressure transmitter, which is installed on the liquid supply pipeline close to one end of the evaporative condensers, and is used for measuring the pressure of the liquid supply pipeline; and a control unit, which is electrically connected with the circulating water pumps, the fans of the evaporative condensers, and the frequency converter and the pressure transmitter, respectively, and is used for receiving the measurement data of the pressure transmitter, and controlling the start-stop number of the circulating water pumps and the fans, and adjusting the operating frequencies of the circulating water pumps and the fans by the frequency converter, according to the measurement data.

2. A chiller exhaust pressure control system as set forth in claim 1, characterized in that, The frequency converter comprises a circulating water pump frequency converter and a fan frequency converter, the circulating water pump frequency converter is electrically connected with the circulating water pumps of the evaporative condensers, and is used for adjusting the operating frequencies of the circulating water pumps, and the fan frequency converter is electrically connected with the fans of the evaporative condensers, and is used for adjusting the operating frequencies of the fans.

3. A chiller exhaust pressure control system as recited in claim 2, wherein, Among the two circulating water pumps of the evaporative condensers, one is a normal circulating water pump, and the other is a standby circulating water pump.

4. A chiller exhaust pressure control system as set forth in claim 3, characterized in that, The number of the circulating water pump frequency converters is at least one, which is used for adjusting the operating frequencies of the normal circulating water pumps.

5. A chiller exhaust pressure control system as recited in claim 2, wherein, The number of the fan frequency converters is at least one, which is used for adjusting the operating frequencies of one of the fans of the evaporative condensers.

6. A chiller exhaust pressure control system as recited in claim 1, wherein, Each of the circulating water pumps and each of the fans of the evaporative condensers has a control end with a separate start-stop function.

7. A chiller exhaust pressure control system as set forth in claim 1, characterized in that, The system further comprises a compressor, which is installed on the suction pipeline, and is used for compressing gaseous refrigerants, and the compressed gaseous refrigerants pass through the evaporative condensers.

8. A chiller exhaust pressure control system as set forth in claim 1, characterized in that, The system further comprises a liquid storage tank, which is installed on the liquid supply pipeline close to an outlet thereof, and is used for storing liquid-phase refrigerants obtained by condensation of the evaporative condensers.

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