Liquid level control of the water distribution tank during the shutdown of the chlor-alkali plant

During the shutdown of the chlor-alkali plant, if it is necessary to control the liquid level in the water distribution tank, this can be achieved through manual operation or by installing a backup automatic control system. Manual operation requires monitoring the liquid level in the water distribution tank and adjusting the water inflow rate promptly to keep the level stable within the set range. If a backup automatic control system is installed, a control strategy for the period of shutdown can be set to regulate the water inflow rate based on changes in the liquid level of the water distribution tank. During low-load periods, in order to prevent excessive water from flowing into the water distribution tank and causing waste, it may be necessary to reduce the water inflow rate or close the inlet valve. At this point, a reasonable water inflow volume can be determined based on the production plan or actual conditions, and corresponding control strategies can be established. In the case of an automatic control system, automatic adjustment of the water inflow rate can be achieved based on the feedback signal from the level sensor. .

During the shutdown of chlor-alkali plants, two methods are commonly used to control the liquid level in the water distribution tank: 1. Sealing method: During shutdown, the inlet, outlet, and bottom drain of the water distribution tank can be sealed off, after which nitrogen or an inert gas is injected into the tank using a compressor to maintain a certain pressure and thus prevent the liquid level from dropping. 2. Replacement method: During the downtime, the water in the water distribution tank can be drained, and then an adequate amount of water can be poured in to maintain a constant water level throughout the downtime. During the low-load operation of chlor-alkali plants, to control the liquid level in the water distribution tank, the following two approaches can be adopted: 1. Adjust the water inflow volume: Modify the amount of water entering the tank to meet the production requirements during low-load periods, while ensuring that the inflow volume does not exceed the capacity of the tank, thereby maintaining a stable liquid level. 2. Operational adjustment: The liquid level in the water distribution tank is controlled by adjusting operational parameters such as the inflow and outflow rates of water to the tank, as well as the opening degree of the bottom discharge port. A PID control system is typically used to achieve automatic level regulation, keeping it stable during low load conditions. For reference only