This article introduces Jinguan Chemical Co., Ltd.'s solution to the problem of inaccurate and unstable liquid level measurement in liquid ammonia storage tank level interlock control. By comparing differential pressure level transmitters, magnetic flap level gauges, andELLThree types of instruments for external liquid level measurement, ultimately selectedELLThe external liquid level gauge effectively solves the problem, improves production efficiency and safety management level.

1、 Background and Issues

Jinguan Chemical Co., Ltd. mainly produces azo dispersed dye filter cake, and the newly built ammonium sulfate workshop uses liquid ammonia as raw material. The original differential pressure level transmitter and magnetic flap level gauge have frequent data fluctuations and large errors when measuring the liquid level of liquid ammonia storage tanks, posing safety hazards.

2、 Comparison and selection of liquid level gauges

1. Differential pressure liquid level transmitter

Principle: Measure the liquid level by measuring the static pressure changes generated by the height of the liquid level.

Problem: The tank is greatly affected by environmental temperature, with obvious gasification phenomena and large liquid level errors in summer.

2. Magnetic flap level gauge

原理：利用浮力原理和磁性耦合作用指示液位。

Problem: Also affected by environmental temperature, when the gas-liquid mixture increases, the magnetic float fluctuates greatly and the measurement is unstable.

3. ELLType external liquid level gauge

Principle: External ultrasonic technology, without contact with the medium inside the tank.

Advantage:

Safety: No contact with toxic or harmful media, no risk of leakage.

Easy installation and maintenance: no hot work, uncleanliness of tanks, and no impact on production.

Reliable and durable: no mechanical moving parts, strictly sealed.

High precision: meets the requirements of chain control and has small measurement errors.

3、 Actual application effect

1. Measurement stability

ELLThe external liquid level gauge shows high reliability in measuring the liquid level of liquid ammonia storage tanks, with little influence from external temperature and pressure changes, and a stable liquid level curve.

2. Process production optimization

by usingELLThe external liquid level gauge has achieved chain control of liquid ammonia storage tank liquid level, improving the automation level and safety of process production.

3. Recognition and Promotion

ELLThe measurement effect of the external liquid level gauge has been recognized by workshop leaders and process technicians, and highly praised by institutions such as the Shaoxing Safety Production Supervision Bureau, which is considering promoting its use in other workshops.

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