Method and apparatus for measuring mass flow and energy content using a differential pressure meter.

摘要

The present invention is a method and apparatus for monitoring in real time the mass and energy flow rate of a gas through a pipeline. The invention determines the ratio of the mass flow rate of pipeline gas flowing through a pipeline compared to the mass flow rate of sample gas tapped from the pipeline line. The invention involves tapping sample gas from the pipeline and flowing the sample gas to a capillary tube or a similar device for creating a pressure differential in a small flow. The sample gas is maintained at substantially the same temperature as the gas in the pipeline while the sample gas is in the capillary tube. The sample gas flows through the capillary tube continuously as controlled by a flow controller at a rate that is independent of the pipeline gas flow rate. A differential pressure cell measures the pressure differential of the sample gas across the capillary tube and also measures the pressure differential of the pipeline gas across an orifice in the pipeline. The mass flow ratio of the pipeline gas flowing through the pipeline to the sample gas flowing through the capillary tube is computed using the pressure differentials measured by the differential pressure cell. The energy content of the pipeline gas is determined by measuring the energy content of the sample gas and relating that value to the mass flow ratio of the pipeline gas compared to the sample gas. If the sample gas is a saturated hydrocarbon and is burned with air at maximum flame temperature, the energy content of the pipeline gas stream is mathematically related to the mass flow rate of the air and the mass flow ratio of the pipeline gas compared to the sample gas. <IMAGE>