How to deal with the unbalanced design of the control valve of pneumatic components

At the beginning of the design of the pneumatic component control valve, because there is no matching, the imbalance of the whole system will be created, which will cause unnecessary loss of energy consumption, so it is possible to strive for perfection at the beginning of the system design.

If full load cannot be achieved due to system imbalance under design conditions, the total investment of the whole plant will not be paid back. When the maximum load is required, the pneumatic element control valve can not handle this condition even when it is fully open. It is very difficult to determine the size of the two-way control valve. Generally, the calculated valve can not be bought in the market, so the size is usually too large. In this way, the balance of the circulation system becomes very critical. Generally speaking, the investment in this part is less than one percent of the total investment in HVAC. Every morning, after a night of shutdown and reset, all power needs to be mobilized to restore comfort as soon as possible. A well-balanced system can be achieved quickly. If the startup time can be saved by 30 minutes, the energy consumption can be saved by 6% every day compared with the working time of 8 hours. This is more than all distribution pumping costs.

In the variable flow distribution, the pumping energy consumption generally accounts for less than 5% of the seasonal consumption of the refrigeration unit. The cost of reducing the indoor temperature by one degree is 10-16%. Therefore, getting the right comfort is the best way to save energy. Therefore, it is necessary to take all measures aimed at reducing the energy consumption of pumping, so that they will not have an adverse impact on the operation of the end device control circuit. The pumping cost can be reduced by increasing the design water temperature difference. T as much as possible and using the variable speed pump with the best positioning Δ P sensor. Under the medium load, the steady PI control is lower than the switch control, so it can also reduce the pumping cost.

But the most important problem is that the size of the compensation pump is too large. The balance valve set by compensation method can show the large size condition. It can be found that all overpressures are located on the balance valve close to the pump. The balance valve of the pneumatic components can be reopened after the corrective measures are taken for the pump. Cycle balancing requires correct tools, up-to-date procedures and effective measuring devices. The manual balance valve of pneumatic components is obviously the most reliable and simple product to obtain the correct flow under the design conditions, and it can always measure the flow for diagnosis. It can also be connected to the differential pressure controller if necessary.