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Determination of fluid parameters

IP.com Disclosure Number: IPCOM000240849D
Publication Date: 2015-Mar-06

Publishing Venue

The IP.com Prior Art Database

Abstract

A method for determining fluid parameters, such as a heat capacity, a calorific value, a methane number, and/or a Wobbe index, of an unknown fluid. An unknown flow of the fluid is set in a sensor device, the sensor device comprising a thermal flow sensor and a pressure sensor device for measuring at least one temperature value, a further parameter, and differential pressure value over a flow restrictor. Using these measurement parameters and calibration data, the calorific value, and/or the Wobbe index, or parameters indicative thereof, of an unknown fluid are calculated. The invention alsorelates to such a sensor device and to a computer program product for carrying out such a method.

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TITLE

Determination of fluid parameters

ABSTRACT

A method for determining fluid parameters, such as a heat capacity ܿߩ, a calorific value ܪߩ, a methane number ܯܰ, and/or a Wobbe index ܹܫ, of an unknown fluid. An unknown flow of the fluid is set in a sensor device, the sensor device comprising a thermal flow sensor and a pressure sensor device for measuring at least one temperature value ܶǡ ܶ, a further parameter, and differential pressure value ȟ݌ over a flow restrictor . Using these measurement parameters ܶǡ ܶǡ ȟ݌ and calibration data, the calorific value ܪߩ, and/or the Wobbe index ܹܫ, or parameters indicative thereof, of an unknown fluid are calculated. The invention also relates to such a sensor device and to a computer program product for carrying out such a method.

TECHNICAL FIELD

The present invention relates to a method for determining fluid parameters of an unknown fluid, in particular a calorific value of the fluid or a parameter related thereto, the fluid being preferably a burnable gas. It further relates to a measurement device and a computer program product configured to carry out said method.

PRIOR ART

Today's natural gas pipelines are organized in vast networks fed by numerous feed-in stations. As the gas in the pipeline system originates from different gas sources, the gas is naturally a mixture that varies over time.

    A calorific value of the natural gas is an important technical and economic fluid parameter that is commonly determined by analysis of the gas composition. The gas


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composition may be measured by means of a gas chromatograph. Such devices are, however, expensive in acquisition as well as in maintenance. Moreover, measurement times are long and consequently, the measurement data are not available in real time but has to be gathered intermittently.

    A further device for determining the calorific value of a natural gas is known from DE 101 22 039 A1. This document suggests using a gas flow meter with two temperature sensors and a heater arranged therebetween. From the two measured temperature values the calorific value of the natural gas is determined by linear interpolation. This method is, however, not as precise as desired. Moreover, a gas flow has to be kept constant during the measurement.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved method for determining a parameter of an unknown fluid. In particular, the method may be for measurement of a burnable gas or a mixture of such gases, in particular a natural gas of a mixture thereof, wherein the fluid parameter may be the calorific value of the fluid or a parameter indicative thereof.

    Accordingly, a method for determining a characteristic parameter, in particular a calorific value ܪߩ or a parameter indicative thereof, of an unknown fluid ݃, the unknown fluid ݃ preferably being a burnable gas, preferably a natural gas, said fluid ݃ flowing in a fluid flo...