Why are two anti-surge valves installed at the outlet of the catalytic main fan?

Generally, two are set up, one large and one small. The smaller one is turned on first; this is probably done for safety reasons

Generally, two valves are installed, one large and one small, which serve as a coarse adjustment and a fine adjustment respectively； It is generally set for segmented control, which is necessary to ensure the safety of the unit.

It highlights the importance of the anti-surge valve of the main fan.

It’s probably major and minor keys, which are more practical

From this design, it is evident of the importance of this main fan; moreover, it has a high air volume. Two anti-surge valves, one large and one small, are installed to allow adjustment to meet the requirements of different operating conditions. The small valve is used for precise control when the air volume is low, while the combination of the large valve and the small valve can meet the system’s needs when the air volume is high.

The exhaust valves at the outlet of the main fan are not necessarily one large and one small; this is determined by the pipeline design parameters and the wind pressure load ratio of the unit. Some units consist of two identical ones. 1. Set for the adjustment accuracy when switching the main fan and starting up with combined air supply. 2. Based on the design parameters of the pipeline and the pressure ratio load of the unit, and in order to ensure a minimum amount of venting for safety in case of an accident, and to prevent both outlet vent valves from failing to open at the same time, two outlet vent valves have been installed.

First of all, it is definitely one large and one small; the main function of the smaller one is to adjust the oxygen content during the oxygen-deficient operation of the regenerator

This post was last edited by zwzavatar on 2022-2-17 at 10:03. The 7th floor’s opinion seems quite reasonable to me. Two surge valves are installed, and the functions of these two valves are actually different. Stall prevention control refers to regulation at the outlet pressure under normal operating conditions; generally, an opening degree of the stall prevention valve that ensures 30% of the rated flow rate is sufficient to meet the stall prevention requirements. Therefore, the first valve to be opened serves primarily an anti-surge function, and its performance curve is certainly most accurate at 30% of the rated flow rate. Another operating condition for the fan is the startup condition, during which the outlet pressure is very low while the air volume is high. To achieve precise control of such a high air flow rate, it is necessary to add another valve. In other words, one valve is primarily used for surge control, while another valve is mainly used for startup control. Therefore, whether to open the valve wider or narrower first to prevent surge depends on the performance of the fan, as well as the optimal operating range specified for the valve design. However, typically a surge control valve consists of one large-capacity valve and one small-capacity valve. Small-capacity valves are primarily used for daily adjustment and venting; they respond quickly, ensuring a smooth venting process. Large-capacity valves, which do not operate under normal conditions, come into play to assist in control when small-capacity valves are unable to perform regulation, thereby ensuring system safety. Precise control of low and high opening degrees is achieved through step control, thereby enabling accurate adjustment in the two operating conditions.

There was one old device, and now there are two.

This post was last edited by shuangwu*an on 2022-3-15 at 16:41. The dual surge valves serve as a double safety mechanism; they are closed under normal conditions. If one of the valves fails, it’s not easy to detect the problem. If it cannot be opened during a surge, that would lead to disaster When operating at the rated wind speed, precise venting adjustments are not always necessary; the blade angle and the outlet butterfly valve can also be used to adjust the air volume. If the system is operating normally yet the surge valve is opened to release the main air, isn’t that a waste of electricity?