Self-operated flow control valve adjusts hydraulic imbalance in heating pipe network

Oct 12,2021

The self-operated flow control valve can accurately adjust the flow, and is easy to operate and stable. The use of self-operated flow control valves not only solves the hydraulic imbalance of the heating pipe network, but also improves the heating effect, saves energy, and has a good effect on the economic and social benefits of heating enterprises.
1 Reasons for hydraulic imbalance 　　 The inconsistency between the actual flow of each thermal user in the heating system and the design required flow is called the hydraulic imbalance of the user. After the heating pipe network is completed, in actual operation, there are often hydraulic imbalance problems, which are mainly caused by the following reasons: ①The engineering design is calculated according to the hydraulic theory and the corresponding data is selected, and the actual pipe values ​​and standards There are differences; ②Due to the limitation of construction conditions (the underground hidden pipe network is complicated so that only pipe fittings such as elbows can be added in the construction), the actual situation of the pipeline is very different from the design situation. The heating pipe network is in actual operation Unable to achieve balance; ③The increase of new users after the completion of the pipe network (such as new network connection, networking, etc.) destroys the original hydraulic balance; ④Improper maintenance of the pipe network affects the hydraulic balance of the pipe network; ⑤Inaccurate , Easy-to-use, low-cost flow control equipment.
Due to the different resistance and coupling relationship between the various loops, it is difficult to balance the flow transmission and distribution, and the control is difficult. This results in poor system operation quality, inaccurate and unstable flow control, and uneven cold and heat at the user end, resulting in operation The room temperature of hot users in good working conditions exceeds the standard and even opens windows to dissipate heat, while the room temperature of hot users in poor operating conditions does not meet the standard. In order to reduce non-compliant users, reduce complaint rates, and increase charging rates, heating companies are forced to use large flow, high pressure or increase heating temperature operation. Although there are fewer low-temperature users, the temperature of high-temperature users exceeds the standard seriously, resulting in a lot of energy waste. The operating cost of the heating enterprise.
Among the various causes of hydraulic imbalance, the hydraulic imbalance caused by the difference between the design and the actual, the construction conditions, the increase of new users, etc., is difficult to avoid in the heating pipe network, but through the accurate and simple control of the flow It is a feasible solution to hydraulic imbalance for heating companies.
2 Commonly used methods to adjust hydraulic imbalance
The more traditional adjustment method of heating enterprises is to adjust the opening degree of the return (supply) valve of the heat user, and the valve usually installed is a gate valve or a butterfly valve. These two kinds of valves are cut-off valves, and the main function is to close. Or open the pipe network of a branch line, by adjusting the valve, it is difficult to accurately achieve the required flow rate. Figure 1 shows the relationship curve between the valve opening and the flow rate. At this time, although the flow rate can vary from 0 to 100% with the increase of the valve opening, it is actually difficult to reach a certain flow rate in the middle, and the regulation performance is poor. Because the flow rate is difficult to adjust accurately, the temperature cannot be adjusted accurately, and the adjustability is poor. Another situation is the mutual influence between several branches. If a branch is opened with a large valve to increase the flow, the flow of the adjacent branch will decrease accordingly, resulting in poor stability.

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