Liquid level detection and control device of closed cooling tower

Abstract

The utility model provides a liquid level detection and control device for a closed cooling tower, which is characterized in that a water replenishing pipeline is externally connected with a municipal water supply pipeline and is communicated to a water replenishing port of the closed cooling tower, and a manual switch valve and a water replenishing electric valve are sequentially arranged on the pipeline along the liquid flow direction; a water replenishing bypass pipeline with a bypass manual valve is connected in parallel between the upstream of the manual switch valve and the downstream of the water replenishing electric valve; the tower bottom drain outlet is externally connected with a blow-off pipeline; a pressure sensor, an adjusting manual valve and a blow-off electric valve are sequentially arranged on the blow-off pipeline along the liquid flow direction; a high liquid level switch and a low liquid level switch are arranged below the tower body by taking the height position of the water replenishing port as a boundary; and the water replenishing electric valve, the pressure sensor, the sewage draining electric valve, the high liquid level switch and the low liquid level switch are respectively connected to a PLC (Programmable Logic Controller) control cabinet and are controlled by the PLC. The liquid level control device of the closed cooling tower is beneficial to stable control of the liquid level of the closed cooling tower, solves the problem that the cooling tower cannot operate normally due to excessive water replenishing or too little water replenishing, and avoids waste of water resources caused by the problem.

Description

Technical Field

[0001] The utility model relates to a liquid level detection and control device for a closed cooling tower. Background Art

[0002] A closed cooling tower is different from an open cooling tower in that there is a separate water circulation system inside the tower, which provides the water required for cooling the tower. During the cooling process of the cooling tower, this separate water circulation system will cause water evaporation, resulting in a drop in the liquid level in the cooling tower. In order to ensure that the water quality of the water circulation system meets the standards and reduce the scaling of the cooling tower heat exchanger caused by calcium and magnesium ions, a portion of the sewage will be actively discharged according to the changes in conductivity, further causing the liquid level to drop. At this time, it is necessary to make up water to ensure that the liquid level meets the requirements. Usually, a mechanical float valve is designed to make up water to control the liquid level. However, excessive water replenishment will lead to a waste of water resources, and too little water replenishment will cause the cooling tower to fail to operate normally. It is mainly manifested in:

[0003] 1. The water capacity of the closed cooling tower is low. The mechanical float valve needs to be automatically opened and closed frequently during use. Frequent use reduces the reliability of the mechanical float valve mechanism, which may cause it to fail to open or close completely.

[0004] 2. The water in the closed cooling tower has a higher conductivity than normal tap water, and contains more impurities such as salt. It is easy for crystallization to occur in the mechanical float valve during the cooling tower shutdown period, which can easily cause loose closure and uncontrolled water inlet.

[0005] 3. Closed cooling towers use mechanical float valves to control the liquid level. The liquid level can usually only be set at a high level, and there is only this one position to control the switch of the mechanical float valve. When the cooling tower stops operating, the water in the circulation system will circulate into the cooling tower, causing the liquid level to increase and water overflow.

[0006] The above are three reasons that easily lead to unstable liquid level control in actual use, affecting the normal use of the closed cooling tower. At the same time, excessive water inflow will lead to waste of water resources. Utility Model Content

[0007] In order to solve the above technical problems, the utility model proposes a closed cooling tower liquid level detection and control device, which helps to stably control the liquid level of the closed cooling tower, solves the problem that the cooling tower cannot operate normally due to excessive or insufficient water replenishment, and avoids the waste of water resources caused thereby.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] A liquid level detection and control device for a closed cooling tower. The closed cooling tower is provided with a water circulation system. The water in the tower circulates in the tower through an internal circulation water pump through the water circulation system. The structural features are:

[0010] Including water supply pipes, sewage pipes, PLC control cabinets, high liquid level switches, and low liquid level switches;

[0011] The water supply pipeline is externally connected to the municipal water supply pipeline and connected to the water supply port of the closed cooling tower. A manual switch valve and a water supply electric valve are sequentially arranged on the pipeline along the liquid flow direction. A water supply bypass pipeline with a bypass manual valve is connected in parallel between the upstream of the manual switch valve and the downstream of the water supply electric valve.

[0012] The sewage outlet at the bottom of the tower is externally connected to the sewage pipe, and the sewage pipe is provided with a pressure sensor, a manual regulating valve and a sewage electric valve in sequence along the direction of liquid flow;

[0013] Taking the height position of the water replenishment port as the boundary, the high liquid level switch and the low liquid level switch are provided at the part below the tower body, a gap is left between the high liquid level switch and the water replenishment port along the height direction for detecting the high liquid level signal of water replenishment, and a gap is left between the low liquid level switch and the bottom end of the tower along the height direction for detecting the low liquid level signal of water replenishment;

[0014] The water replenishment electric valve, pressure sensor, sewage discharge electric valve, high liquid level switch and low liquid level switch are respectively connected to the PLC control cabinet and controlled by the PLC.

[0015] Furthermore, the water inlet of the internal circulation water pump is connected to the bottom end of the tower through the internal circulation output pipeline, and the water outlet is connected to the top end of the tower through the internal circulation reflux pipeline.

[0016] Compared with the prior art, the beneficial effects of the utility model are embodied in:

[0017] The utility model configures a pressure sensor on the sewage pipe of the closed cooling tower, and uses the static pressure difference generated by the liquid level as the basis for the PLC control cabinet to control the on-off of the water supply pipe; at the same time, a water supply bypass pipeline with a bypass manual valve is configured for the water supply pipeline, and in the event of a water supply electric valve failure or a PLC control cabinet failure, manual water supply can be performed through the water supply bypass pipeline; a high liquid level sensor and a low liquid level sensor are also configured to further ensure the reliability of the device in controlling the liquid level of the closed cooling tower, avoid excessive or insufficient water supply, avoid the waste of water resources caused thereby, and ensure the smooth operation of the closed cooling tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the utility model;

[0019] Figure 2 It is a circuit schematic diagram of the utility model.

[0020] In the figure, 1 is a closed cooling tower; 11 is a water supply port; 2 is an internal circulation water pump; 3 is a water supply pipeline; 31 is a manual switch valve; 32 is a water supply electric valve; 33 is a bypass manual valve; 34 is a water supply bypass pipeline; 4 is a sewage pipeline; 41 is a pressure sensor; 42 is an adjusting manual valve; 43 is a sewage electric valve; 5 is a PLC control cabinet; 61 is a high liquid level switch; 62 is a low liquid level switch. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution in the embodiments of the utility model will be clearly and completely described below in combination with the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0022] The closed cooling tower 1 is provided with a water circulation system, and the water in the tower is circulated in the tower through the internal circulation water pump 2 through the water circulation system. The water inlet of the internal circulation water pump 2 is connected to the bottom end of the tower through the internal circulation output pipe, and the water outlet is connected to the top end of the tower through the internal circulation reflux pipe.

[0023] Please refer to Figure 1 to Figure 2 , the liquid level detection and control device of the closed cooling tower 1 of this embodiment includes a water supply pipe 3, a sewage pipe 4, a PLC control cabinet 5, a high liquid level switch 61, and a low liquid level switch 62;

[0024] The water supply pipe 3 is externally connected to the municipal water supply pipe and connected to the water supply port 11 of the closed cooling tower 1. A manual switch valve 31 and a water supply electric valve 32 are sequentially arranged on the pipe along the liquid flow direction. A water supply bypass pipe 34 with a bypass manual valve 33 is connected in parallel between the upstream of the manual switch valve 31 and the downstream of the water supply electric valve 32.

[0025] The bottom sewage outlet of the tower is connected to a sewage pipe 4, on which a pressure sensor 41, a regulating manual valve 42 and a sewage electric valve 43 are arranged in sequence along the liquid flow direction;

[0026] Taking the height position of the water replenishment port 11 as the boundary, a high liquid level switch 61 and a low liquid level switch 62 are provided below the tower body. A gap is left between the high liquid level switch 61 and the water replenishment port 11 along the height direction for detecting the high liquid level signal of water replenishment, and a gap is left between the low liquid level switch 62 and the bottom end of the tower along the height direction for detecting the low liquid level signal of water replenishment;

[0027] The water replenishment electric valve 32, the pressure sensor 41, the sewage discharge electric valve 43, the high liquid level switch 61, and the low liquid level switch 62 are respectively connected to the PLC control cabinet 5 and controlled by the PLC.

[0028] The following is an example of how this device works:

[0029] The closed cooling tower 1 circulates in the tower under the action of the internal circulation water pump 2. When the water vapor evaporates and the sewage is discharged through the sewage pipe 4, the water level in the tower drops. The pressure sensor 41 will detect the static pressure drop caused by the drop in the liquid level, and transmit the detected pressure value signal to the PLC control cabinet 5. The PLC control cabinet 5 will compare it with the preset pressure value. After determining that it is lower than the preset pressure value, the water supply electric valve 32 is controlled to be gradually opened. At this time, the municipal water will be sent into the tower through the water supply pipe 3 with the manual switch valve 31 and the water supply electric valve 32 through the water supply port 11;

[0030] When the pressure sensor 41 detects the static pressure rise caused by the liquid level rise, and transmits the detected pressure value signal to the PLC control cabinet 5, the PLC control cabinet 5 will compare it with the preset pressure value again, and after determining that it is higher than the preset pressure value, it will control the water supply electric valve 32 to gradually close until it is completely closed;

[0031] In order to ensure the reliability of the liquid level control of the closed cooling tower 1 by the device, the device is further configured with a high liquid level sensor and a low liquid level sensor. When the water level in the tower is higher than the height position where the detection end of the high liquid level sensor is located, the PLC control cabinet 5 controls the water supply electric valve 32 to close according to the liquid level signal fed back by the high liquid level sensor; when the water level in the tower is lower than the height position where the detection end of the low liquid level sensor is located, the PLC control cabinet 5 controls the water supply electric valve 32 to open according to the liquid level signal fed back by the low liquid level sensor;

[0032] In addition, the device configures a water supply bypass pipeline 34 with a bypass manual valve 33 for the water supply pipeline 3. In the event of a failure of the water supply electric valve 32 or a failure of the PLC control cabinet 5, manual water supply can be performed through the water supply bypass pipeline 34;

[0033] The regulating manual valve 42 on the sewage pipe 4 is used to regulate and control the sewage discharge amount, thereby reducing the adverse effects of water pressure shock on the pressure sensor 41 during sewage discharge.

[0034] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A liquid level detection and control device for a closed cooling tower, wherein the closed cooling tower is provided with a water circulation system, and the water in the tower is circulated in the tower through an internal circulation water pump through the water circulation system, wherein the closed cooling tower is provided with a water circulation system, and ... Including water supply pipes, sewage pipes, PLC control cabinets, high liquid level switches, and low liquid level switches; The water supply pipeline is externally connected to the municipal water supply pipeline and connected to the water supply port of the closed cooling tower. A manual switch valve and a water supply electric valve are sequentially arranged on the pipeline along the liquid flow direction. A water supply bypass pipeline with a bypass manual valve is connected in parallel between the upstream of the manual switch valve and the downstream of the water supply electric valve. The sewage outlet at the bottom of the tower is externally connected to the sewage pipe, and the sewage pipe is provided with a pressure sensor, a manual regulating valve and a sewage electric valve in sequence along the direction of liquid flow; Taking the height position of the water replenishment port as the boundary, the high liquid level switch and the low liquid level switch are provided at the part below the tower body, a gap is left between the high liquid level switch and the water replenishment port along the height direction for detecting the high liquid level signal of water replenishment, and a gap is left between the low liquid level switch and the bottom end of the tower along the height direction for detecting the low liquid level signal of water replenishment; The water replenishment electric valve, pressure sensor, sewage discharge electric valve, high liquid level switch and low liquid level switch are respectively connected to the PLC control cabinet and controlled by the PLC.

2. The closed cooling tower liquid level detection and control device according to claim 1 is characterized in that: The water inlet of the internal circulation water pump is connected to the bottom end of the tower through the internal circulation output pipeline, and the water outlet is connected to the top end of the tower through the internal circulation reflux pipeline.

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