The use of flange gate valve in the operation regulation of heating system

The use of flange gate valve in the operation regulation of heating system

Hydraulic misalignment is one of the factors affecting the quality of heat supply. Heating system operation, due to hydraulic disorders caused by the distance from the heat source or floor above and below the different users appear overcooling or overheating and other anomalies, the use of balancing valves to regulate, to achieve the design of the hydraulic condition, to ensure the stability of the heating system.

Introduction

Hydraulic misalignment is one of the factors affecting the quality of heat supply. With the national emphasis on energy saving and environmental protection, municipal centralized heat supply in urban heating has been the direction and trend. In recent years, the rapid development of the real estate industry, the heating range of residential neighborhoods is also increasing, reaching hundreds of thousands of m2 has not been uncommon. But likewise, it causes hydraulic disorders and other abnormal phenomena will be more prominent. Especially the implementation of centralized heating sub-metering reform policy, the quality of heating directly affects the people's standard of living and the implementation of charge metering, so the heating system operation and regulation must be enough attention.

1. Heating system operation condition analysis

Hydraulic conditions refer to the system pipe network pressure, flow, and differential pressure. Hydraulic balance is manifested in the reasonable distribution of user flow. In a heat supply pipe network, water is the heat carrier medium, and the reasonable distribution of flow is the basis of the balance of thermal conditions. Calculation of hydraulic working conditions involves determining the user flow in theoretical conditions based on pipe limitations and system pipeline characteristic resistance. The heating system is a complex hydraulic system where the hydraulic conditions between loops affect and constrain each other. Any changes in user flow during operation will redistribute flow among users, leading to hydraulic disorders and uneven heating. The hydraulic condition of the heating system is determined by the intersection of the pump's output pressure working curve and the external network's characteristic curve. The water pressure diagram represents the external network pressure conditions for safe operation and optimal operating point determination. During operation, hydraulic condition adjustment is based on the system pressure diagram to distribute heat media according to user flow calculations. Hydraulic balancing equipment is used to achieve system water pressure diagram operation and formation alignment with hydraulic working condition design. This ensures uniform and reasonable flow distribution, achieving hydraulic balance for safe and reliable heating system operation, stability, and quality.

2. Heating system hydraulic disorder analysis Result: - The heating system is experiencing a hydraulic disorder that needs to be addressed promptly.

Heating system hydraulic disorder is a common problem. The main reasons exist in: one. The design of the heating network hydraulic calculation is not accurate, only note the most unfavorable point (usually at the end of the system) necessary to use the head, and other points of the head is always greater than the calculated value, the closer to the location of the heat source of the head of the position of the head of the head of the head of the head of the head of the head of the head of the head of the head. And the loop itself does not have the independent hydraulic adjustment function, there is bound to be a flow distribution deviation from the design state, resulting in the user hot and cold uneven hydraulic disorders (usually near the end of the overheating, the far end is not hot). Secondly, in the case of reasonable system design, the pump selection is too large, the operation of the flow deviates from the design state (large flow small temperature difference), also leading to the system's hydraulic disorders. Third, the increase in the number of new users and the expansion of the heating network, but not in time to transform the calibration, but only to replace the pump (increase the flow and head of the pump) to make the system more complex operation and management, resulting in new hydraulic disorders. Usually set up a large flow, high head pumps, using a large flow of small temperature difference in this way and can not solve the hydraulic imbalance phenomenon. According to relevant information, large flow small temperature difference in the operation of the system will increase the investment of more than 20%, consume 15% -20% of the thermal energy, more than 30% of the power consumption.

3 balance valve on the heating system hydraulic disorder regulation

In the introduction of the mouth of the pipe section to install throttle orifice or install gate valves, shut-off valves, etc., balanced piping system resistance and regulate the flow rate, eliminating the user system residual pressure head. However, the disadvantage is that the aperture of the throttling orifice plate is calculated according to the design conditions, when the heat load changes, it is necessary to recalculate and replace the throttling orifice plate. Moreover, the aperture of the throttling orifice plate is too small and easily clogged.

Similarly, gate valves, globe valves have poor regulating performance, essentially only appropriate as a shut-off valve.

Especially after the implementation of household measurement measures, if any user system valve opening changes, due to throttle orifice plate and other fixed flow rate of its regulation, will be redistributed to the flow rate of new water disorders generated after the phenomenon, the need to recalculate the adjustment, action lag, operational complexity, poor flexibility.

In recent years, the installation of balance valves, self-operated flow control valves, and self-operated differential pressure control valves has shown a high degree of automation, flexibility, and agility. These valves are categorized as control valves, with the core equipment being the valve body. The regulating principle involves changing the spool stroke to adjust the throttling area and valve resistance, thereby regulating flow and achieving flow balance in the system without external power supply. The balance valve maintains a constant opening regardless of flow rate, the self-operated flow control valve adjusts its opening based on flow rate changes, and the self-operated differential pressure control valve adjusts its opening based on pressure difference changes. Compared to other regulating devices, the balance valve offers linear flow characteristics, accurate opening indication, and a locking device to prevent unauthorized changes to the opening.

3.3 Heating system operation regulation, the centralized regulation of the system flow does not change, because the system flow does not change, the differential pressure of the pipe network will not change, and thus the balance valve, self-operated flow control valve, self-operated differential pressure control valve openings do not change the distribution of the flow of the network also does not change, so can be selected. But to choose the flow control valve or balance valve first, such as the amount of regulation should be used to balance the valve. For the user to change the flow of autonomous regulation, because of its indoor system more than a common riser of the two-pipe system. Therefore, if the common riser inlet balancing valve, relying on the user temperature control valve multiple actions, can achieve different users of the room temperature requirements, and thus the balance valve can be selected. If the common riser inlet installed self-operated differential pressure control valve, can make the common riser differential pressure to remain unchanged, is conducive to the temperature control valve to control the flow of radiator regulation, so the selection of self-operated differential pressure control valve has the best results. As the user's independent adjustment, the pipe network flow is also changed, so the pipe network branches are also suitable for the installation of self-operated differential pressure control valve.

1. 平衡阀在供暖系统中的应用 2. 平衡阀在空调系统中的应用 3. 平衡阀在工业生产中的应用 4. 平衡阀在水处理系统中的应用

A unit of heating system renovation process installed balance valve, after several heating season operation results show that the installation of the balance valve can be a good solution to the system's hydraulic imbalance phenomenon, improve the quality of heating, and achieved good energy efficiency and economic benefits. Operation comparison is shown in Table 1.

District Heating Installed Balance Valve Flow Deviation Comparison Table | Item | Maximum Deviation (%) | Average Deviation (%) | |------|-----------------------|----------------------| | A | 5 | 2 | | B | 4 | 1.5 | | C | 6 | 2.3 |

Balance valve in the operation of the heating system regulating the use of.

The data indicate that by installing balancing valves in the district heating system, each branch system can achieve the designed flow distribution, ensuring indoor temperatures of over 18°C for users who have not been able to adjust their heating for many years. The system can address issues of over-flow and under-flow, ensuring that the calculated flow values are met for end users and resolving problems of overheating and overcooling, thus stabilizing the heating effect. Additionally, users who have made private modifications to the pipeline resulting in excessive resistance in some units can achieve the desired flow distribution through balancing valves.

5 Balance valve on the heating system operation regulation experience

1. The elimination of hot and cold uneven phenomenon ensures the quality of heat supply and reduces user complaint rates. 2. The full play of heat source equipment capacity is achieved. 3. The purpose of energy saving in operation regulation is achieved through accurate regulation of the heating system based on temperature differences and outdoor temperature. 4. Ensuring that circulating water pumps operate in the high-efficiency zone saves operating costs and extends the service life of the pumps.

6 Conclusion Thank you for your attention and support.

① The application of balancing valves in the heating system achieves hydraulic balance, ensuring safe and reliable operation, hydraulic stability, and heating quality. ② Due to the prevalence of large diameter entry pipes in single building indoor heating systems, the use of balancing valves for regulating the heating pipe network system is necessary for hydraulic balance. Similarly, in residential district applications, the city heating system at the site level is also a method to achieve hydraulic balance. ③ The proper arrangement of loops and selection of pipe diameters based on hydraulic balance principles is essential for achieving system static balance. However, the configuration of balancing valves should not replace the setup of circuits and hydraulic balance calculations. ④ Hydraulic balance in the heating system can save energy by 15-20%, and the application of hydraulic balance technology is an effective way to improve the current state of heating systems, promoting energy-saving renovations with significant economic and social benefits.