1. Overview

Sulfur acid production equipment usually adopts solid sulfur melting refining or liquid sulfur refining, and stores it in fine sulfur tanks. After re-precipitation treatment, the refined sulfur is pumped through the fine sulfur tank to the sulfur burning furnace, and atomized by the high-efficiency sulfonation gun to generate high-temperature SO₂ flue gas. During the operation of the sulfuric acid plant, the liquid level of the refined sulfur tank and the refined sulfur tank is in a dynamic state. Due to control or instrument failure, refined liquid sulfur often overflows from tanks and tanks to the environment, which not only pollutes the environment, but also may cause injury to personnel. In addition, the tank and tank level may be emptied, resulting in damage to the fine sulfur pump and disruption of production. Therefore, a complete set of automatic tank and tank level control technology is an effective safety guarantee to avoid overflow and low liquid level.

2. Automatic control scheme

In order to ensure the stability of the supply of raw materials and the reliability of the refined sulfur tank, two large refined sulfur tanks are usually designed to store refined liquid sulfur. The capacity of the large sulfur tank is determined according to the size of the device and storage time, and the basic storage time should meet the consumption demand of 15 to 30 days. According to the storage time difference of fine sulfur, the large tank can also further precipitate impurities in liquid sulfur to the bottom of the tank through physical sedimentation, thereby reducing the ash content in the system. Therefore, it is very important to realize automatic filling of large sulfur tank and automatic control of liquid level of tank and tank. For this reason, we specially designed the automatic control scheme of large sulfur tank.

PID flow chart

3. Interlocking condition design table

4. Automatic liquid level control

● Two large tanks of refined sulfur are used alternately during the production process, and the time difference between alternating use is used to precipitate the ash in liquid sulfur. The liquid level of the two tanks is kept within the range of 70% of the liquid level change, so the automatic control of the liquid level is the key to ensure that the large tank is neither overflow nor empty, so as to meet the requirements of automatic control. Therefore, tank pouring control is the core of automatic control of large tanks.

● Fine sulfur tank as the storage tank of fine sulfur pump, its main function is to transport liquid sulfur in the fine sulfur tank to the sulfur burning furnace. The tank is designed with a small storage volume, usually 50 to 70 cubic meters, and a tank depth of 2 meters. The minimum suction of the fine sulfur pump is required to be located at 0.4 meters, but in order to avoid damage to the shaft sleeve (the shaft sleeve is located at 1 meter), the minimum liquid level needs to be set at 1.1 meters. At the same time, the fine sulfur tank is equipped with an overflow safety upper limit of 1.8 meters. Therefore, the adjustable liquid level range of the fine sulfur tank is 0.7 meters, equivalent to 35% of the volume, and the adjustment amount is 17.5 to 24.5 cubic meters. As the transit tank of the large sulfur tank, in order to prevent the failure of the pipeline from the large sulfur tank to the fine sulfur tank, the fine sulfur tank needs to have an emergency recovery ability of one hour. Therefore, the liquid level of the fine sulfur tank should be controlled at about 1.5 meters, accounting for about 75% of the capacity. In view of this, the liquid level can be automatically controlled by PID.

5. Guarantee of automatic control

The technical scheme of automatic control is the basis for the realization of long-term stable operation, and reasonable instrument selection and installation is the key. Lilly Technology recommends the use of radar level gauges and diaphragm static pressure level gauges in the liquid level measurement of fine sulfur tanks and tanks. For more information on selection and installation specifications, please feel free to contact us.