Flow balance control system between cold water primary pump and cold water secondary pump

Abstract

A flow balance control system between a cold water primary pump and a cold water secondary pump comprises a water return pipeline; a water supply line; the cold water pipe is connected with the water return pipeline through N groups of refrigeration units which are arranged in parallel, and the water inlet end of each group of refrigeration unit is provided with a cold water primary pump; the cold water pipe is connected with the water supply pipeline through N groups of cold water secondary pumps which are arranged in parallel; the cold water pipe is further connected with the water return pipeline through a bypass pipe, and an electric proportioning valve is arranged on the bypass pipe; and the PLC is simultaneously connected with the cold water primary pump, the cold water secondary pump, the electric proportioning valve, the ultrasonic flowmeter and the water flow indicator. According to the scheme, aiming at the problem that the backflow flow of the secondary pump is Q2-Q1, the flow of the bypass pipeline can be actively monitored, a signal is sent to the PLC, the PLC dynamically adjusts the operation frequency of the cold water secondary pump, and large-temperature-difference and small-flow operation is achieved step by step.

Description

Technical Field

[0001] The utility model relates to the technical field of heating and ventilation, and in particular to a flow balance control system between a primary cold water pump and a secondary cold water pump. Background Art

[0002] In the air-conditioning room, the chiller is usually equipped with a dedicated pump (primary pump), which is linked to the start and stop of the chiller to improve the safety and reliability of the chiller. Multiple chillers share a set of cold water circulation pumps (secondary pumps) to send the chilled water from the cold source side to the user side to transfer the "cold" to the air-conditioning area and release it, thereby achieving the purpose of cooling.

[0003] Setting up a primary pump can prevent the evaporator of the chiller from lacking water (preventing the evaporator temperature from being too low, causing ice and cracking the evaporator coil) and causing equipment damage. For safety reasons, the primary pump is generally selected for fixed frequency control, that is, the water delivery flow rate Q1 is relatively fixed, and the power is relatively small. The secondary pump is mainly responsible for delivering refrigerant water to users over long distances. It has a large power and needs to adjust the flow rate Q2 in time due to timely changes in the cold load at the user end to better meet user needs and minimize delivery energy consumption.

[0004] Since the primary pump and the secondary pump serve different objects, the control requirements are also different. However, the two are connected in series in the same chilled water circulation pipeline system, cooperating with each other and acting on the circulating water system together, jointly affecting the flow, pressure, pressure difference and temperature parameters of the system.

[0005] At present, the pressure differential bypass valve is mostly used to adjust the flow balance between the primary pump and the secondary pump. The pressure differential setting value of the pressure differential bypass valve focuses on ensuring the pressure relief of the primary pump. However, when Q2>Q1 (for example, the primary pump works normally and Q1 maintains a normal value, but due to the increase in the load at the end of the air conditioner, the "pressure difference of the supply and return water main" decreases and is less than the set pressure difference value, the secondary pump control system will automatically increase the operating frequency of the water pump, increase the speed, and increase the flow of the secondary pump). In this case, the pressure differential bypass valve will default to the secondary pump overpressure and open the pressure relief smoothly. In other words, the secondary pump refluxes the flow Q2-Q1, and it is not cooled by the refrigeration unit, but is directly delivered to the user end. In other words, the energy consumption of the secondary pump to transport Q2-Q1 is actually wasted, but the management personnel are not aware of it.

[0006] Therefore, in view of the shortcomings of the prior art, it is necessary to design a flow balance control system between the primary cold water pump and the secondary cold water pump to solve the above problems. Utility Model Content

[0007] In order to overcome the above-mentioned deficiencies in the prior art, the utility model aims to provide a flow balance control system between a primary chilled water pump and a secondary chilled water pump.

[0008] In order to achieve the above-mentioned purpose and other related purposes, the technical solution provided by the utility model is: a flow balance control system between a primary cold water pump and a secondary cold water pump, comprising:

[0009] Return pipe;

[0010] Water supply pipelines;

[0011] A cold water pipe, wherein the cold water pipe is connected to the return water pipeline through N groups of refrigeration units arranged in parallel, and a cold water primary pump is provided at the water inlet end of each group of refrigeration units; the cold water pipe is connected to the water supply pipeline through N groups of cold water secondary pumps arranged in parallel; the cold water pipe is also connected to the return water pipeline through a bypass pipe, and an electric proportional regulating valve, an ultrasonic flow meter and a water flow indicator are provided on the bypass pipe;

[0012] A PLC controller is connected to the primary cold water pump, the secondary cold water pump, the electric proportional control valve, the ultrasonic flow meter and the water flow indicator at the same time.

[0013] The preferred technical solution is: a return water pressure sensor is provided on the return water pipeline.

[0014] The preferred technical solution is: a water supply pressure sensor is provided on the water supply pipeline.

[0015] The preferred technical solution is that the PLC controller is simultaneously connected to the return water pressure sensor and the water supply pressure sensor signals.

[0016] Due to the application of the above technical solution, the utility model has the following beneficial effects:

[0017] The utility model proposes a flow balance control system between a cold water primary pump and a cold water secondary pump. To address the above-mentioned problem of "secondary pump reflux flow loss Q2-Q1", the flow size and direction of the bypass pipeline can be actively monitored, and the signal can be sent to a PLC controller. The PLC controller automatically adjusts the operating frequency of the cold water secondary pump to gradually achieve "large temperature difference and small flow" operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a flow balance control system between a primary cold water pump and a secondary cold water pump involved in the utility model. DETAILED DESCRIPTION

[0019] The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0020] See also Figure 1. It should be noted that in the description of the present utility model, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. Terms such as "horizontal", "vertical", and "overhanging" do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0021] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Example:

[0023] like Figure 1 As shown, a flow balance control system between a primary cold water pump and a secondary cold water pump is provided, comprising:

[0024] Return pipe 1;

[0025] Water supply pipeline 2;

[0026] The cold water pipe 3 is connected to the return water pipeline 1 through N groups of refrigeration units 4 arranged in parallel, and a cold water primary pump 5 is provided at the water inlet end of each group of refrigeration units 4; the cold water pipe 3 is connected to the water supply pipeline 2 through N groups of cold water secondary pumps 6 arranged in parallel; the cold water pipe 3 is also connected to the return water pipeline 1 through a bypass pipe 7, and an electric proportional regulating valve 8, an ultrasonic flow meter 10 and a water flow indicator 11 are provided on the bypass pipe 7;

[0027] The PLC controller 9 is connected to the primary cold water pump 5, the secondary cold water pump 6, the electric proportional control valve 8 (for controlling the flow in the bypass pipe 7), the ultrasonic flow meter 10 (for monitoring the flow in the bypass pipe 7) and the water flow indicator 11 (for monitoring the water flow direction in the bypass pipe 7).

[0028] like Figure 1 As shown, in an exemplary embodiment of the present utility model, the PLC controller 9 is simultaneously connected to the return water flow sensor, the supply water flow sensor, the return water temperature sensor and the supply water temperature sensor signals.

[0029] Specific:

[0030] Q1 represents the delivery flow rate of the chilled water primary pump 5 , and Q2 represents the delivery flow rate of the chilled water secondary pump 6 .

[0031] 1. When Q2>Q1, the return flow of the cold water secondary pump 6 through the bypass pipe 7 is Q2-Q1. This system can reduce the return flow Q2-Q1 in steps, so that Q2 decreases, and the PLC controller 9 controls the frequency of the cold water secondary pump 6. The temperature difference △T (the temperature difference between the water temperature in the return pipe 1 and the water supply pipe 2) will gradually expand, and Q2 will gradually tend to Q1, thereby achieving a new flow balance and maintaining a large temperature difference (i.e., large temperature difference and small flow).

[0032] 2. If, during the above process, Q2 is close to Q1, and the temperature difference △T continues to expand and exceeds the upper limit of the set value threshold (or the water temperature in the water supply pipeline 2 exceeds the upper limit), the control center instructs "add machine" to start a cold water primary pump 5, and Q1 instantly jumps, causing Q1>Q2 (cold water primary pump 5 reflux situation);

[0033] 3. When Q1>Q2, the cold water secondary pump 6 returns the flow Q1-Q2 through the bypass pipe 7. This system can reduce the return flow Q1-Q2 in steps to increase Q2. The PLC controller 9 controls the cold water secondary pump 6 to increase the frequency slightly and make full use of the cold water primary pump 5. The temperature difference △T will gradually decrease (or the water temperature in the water supply pipeline 2 will gradually decrease), Q2 will gradually increase and approach Q1, thereby achieving a new flow balance and maintaining a higher temperature difference (i.e., large temperature difference and small flow).

[0034] Therefore, the utility model has the following advantages:

[0035] The utility model proposes a flow balance control system between a cold water primary pump and a cold water secondary pump. To address the above-mentioned problem of "secondary pump reflux flow loss Q2-Q1", the flow size of the bypass pipeline can be actively monitored, and the signal is sent to a PLC controller. The PLC controller automatically adjusts the operating frequency of the cold water secondary pump to gradually achieve "large temperature difference and small flow" operation.

[0036] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A flow balance control system between a primary cold water pump and a secondary cold water pump, characterized in that: include: Return pipe; Water supply pipelines; A cold water pipe, wherein the cold water pipe is connected to the return water pipeline through N groups of refrigeration units arranged in parallel, and a cold water primary pump is provided at the water inlet end of each group of refrigeration units; the cold water pipe is connected to the water supply pipeline through N groups of cold water secondary pumps arranged in parallel; the cold water pipe is also connected to the return water pipeline through a bypass pipe, and an electric proportional regulating valve, an ultrasonic flow meter and a water flow indicator are provided on the bypass pipe; A PLC controller is connected to the primary cold water pump, the secondary cold water pump, the electric proportional control valve, the ultrasonic flow meter and the water flow indicator at the same time.

2. A flow balance control system between a primary cold water pump and a secondary cold water pump according to claim 1, characterized in that: A return water pressure sensor is arranged on the return water pipeline.

3. A flow balance control system between a primary cold water pump and a secondary cold water pump according to claim 2, characterized in that: A water supply pressure sensor is arranged on the water supply pipeline.

4. A flow balance control system between a primary cold water pump and a secondary cold water pump according to claim 3, characterized in that: The PLC controller is simultaneously connected to the return water pressure sensor and the supply water pressure sensor signals.

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