Boiler water level detection instrument - dual chamber balance vessel

1、 Introduction to Double Chamber Balanced Container:

The dual chamber balanced container is a cleverly structured steam drum water level measurement device with a certain self compensation ability. Its main structure is shown in Figure 1. Above the reference cup, there is a circular funnel-shaped structure that divides the entire dual chamber balancing container into upper and lower parts. In order to distinguish it from a single chamber balancing container, it is called a dual chamber balancing container. For the convenience of introduction, based on the functional characteristics of each main part, they are respectively named as condenser chamber, reference cup, overflow chamber, and connector. In addition, the double chamber balance container steam drum water level measuring device is referred to as the container in the article.

IIBoiler water level detection instrument - dual chamber balance vessel：

Under normal operating conditions, the water level inside the boiler drum cannot be directly measured, so the method of measuring with an outlet pipe is often used. But its disadvantage is that there is a large temperature difference between the outlet pipe and the steam drum, resulting in a large difference in water density and the inside of the steam drum, which causes certain measurement errors. The reason for using a dual chamber equilibrium container is that during its operation, saturated steam condenses and releases heat in the chamber, heating the positive pressure compensation tube and negative pressure compensation tube, and providing sufficient protective layer on the outer layer of the equilibrium container. Reduced heat loss, making the temperature of the equilibrium container close to the temperature inside the steam drum. Thus, the density of water in the positive pressure compensation tube and negative pressure tube is approximately equal to the density of water in the steam drum under any operating conditions; Due to the correct selection of the height of the positive pressure compensation tube, no matter how the pressure inside the steam drum changes when the water level in the steam drum is constant, the pressure change values of the positive pressure compensation tube and the negative pressure tube are equal. Therefore, the differential pressure output of the dual chamber balance container remains unchanged, that is, the water level indicated by the low water level gauge remains unchanged. Once the water level in the steam drum changes, the differential pressure output by the balance container also changes linearly, so the low water level indicator can timely display the water level in the steam drum.

IIIBoiler water level detection instrument - dual chamber balance vesselDebugging steps:
When the system is not working (boiler steam drum level is zero): On the premise of ensuring that the positive and negative pressure chambers are filled with condensed water, close the balance valve, open the positive and negative phase valves, and at the same time, open the vapor-liquid phase valve of the dual chamber balance container At this point, the output should be 20MA and at full range Adjust the output to 4MA on site and perform negative range shift on the zero point
2. When the system is working (boiler steam has liquid level): On the premise of ensuring that the positive and negative pressure chambers are filled with condensed water, close the balance valve, open the positive and negative phase valves, and at the same time close the vapor-liquid phase valves of the dual chamber balance container
When the measurement system is working normally, the three valve conditions are: the balance valve is closed; The positive and negative phase valves are open The vapor-liquid phase valve of the dual chamber equilibrium container is opened