Apparatus and method for determining a liquid level in a steam drum

A method for determining a density-compensated liquid level in a vessel containing a mixture of liquid and/or vapor, comprising the steps of:

• providing a processing apparatus, including one or more pressure sensors and an integral microprocessor;
• measuring an operating pressure of the mixture using the processing apparatus;
• measuring a differential pressure between the mixture of liquid and vapor in the vessel and a constant reference leg using the processing apparatus;
• calculating the respective specific gravities of the liquid and vapor portions of the mixture based on the operating pressure using the microprocessor of the processing apparatus;
• and
• computing the density-compensated liquid level in the vessel using the microprocessor of the processing apparatus based on the calculations of specific gravity and the measured differential pressure.

A method for determining a density-compensated liquid level of drum contents at or near a saturated condition, comprising the steps of:

• providing a processing apparatus, including one or more pressure sensors and an integral microprocessor;
• measuring an operating pressure within the drum using the processing apparatus;
• measuring a differential pressure between the drum contents and a constant reference leg using the processing apparatus;
• confirming that the drum contents are at or near a saturated condition based on the measured operating pressure;
• and
• computing the density-compensated liquid level in the drum using the microprocessor of the processing apparatus based on calculations of specific gravity of the respective liquid and vapor portions of the drum contents and the measured differential pressure.