NZ541355A - Increased-accuracy gas energy meter - Google Patents

Abstract

The invention relates to a method and device for more accurate measurement of a gas supply by means of a gas meter (1). A gas meter (1) comprising a through-flow sensor (1) for determining a measuring signal (Vs, Vns, Ms, Es) for the amount of consumption and energy consumption of gas (3a) is already known. A consumption-weighted correction factor (F) is determined by weighted averaging of a sensor error factor (fi, fi , fi , fi ) of the gas meter (1) with a consumer profile (li, li , Li) which is characteristic for the location where gas is supplied (14), and the measuring signal (Vs, Vns, Ms, Es) is converted into a corrected consumption or output value (Vn, M, E) with the correction factor (F). Examples include inter alia: operation of the gas meter (1) as a volume, mass or energy meter (10); formulation in order to determine the correction factor (F) with sensor error factors (fi, fi , fi , fi ) and consumption profiles (li, li , Li) in relation to volume, mass or energy, and measuring signal correction for non-registering or registering gas meters (1).

Description

54 13 5 s VERIFICATION STATEMENT FOR TRANSLATION INTERNATIONAL PATENT APPLICATION PCT/CH2003/000055 I, Carole Jean Metcalfe, of 17 Forbes Crescent, Larbert, FK5 3LX, Scotland, hereby declare that I am conversant with the German and English languages and that I am the translator of the document attached and certify that to the best of my knowledge and belief the following is a true and correct English translation of International Patent Application PCT / CH2003/000055. 30th June 2005 1 DESCRIPTION Increased-accuracy gas energy meter TECHNICAL FIELD The present invention relates to the field of gas supply measurement with flow sensors and in particular thermal flow sensors. It starts from a method and 10 a gas meter for measuring gas consumption according to the preamble of the independent claims.

STATE OF THE ART A gas meter which is calibrated as an energy measur ing device is disclosed in WO 01/96819 A1. The calibration is based on the fact that sensor signal values are determined dependent upon the flow rate of a calibration gas and are stored in the gas meter in 20 the form of a sensor calibration curve. The sensor intellectual property officf of n z 3 I JAN 2008 calibration curve or the sensor signal values are multiplied by a signal conversion factor and a calorific value factor for the basic gas mixture so that the obtained product indicates gas consumption in an energy unit. With a further correction factor, the actual heat value of a supplied gas mixture can be taken into account at least approximately in the energy calibration. As actual heat value, a measured heat value which is averaged over a specific time span can be used. It is disadvantageous that an external unit is required to determine the heat value.

In EP 1 227 305, a method and a gas meter for determining a gas consumption from a corrected mass flow signal or energy supply signal are disclosed. On the static gas, diffusivity and therefrom a gas-specific correction value f* for the mass flow or energy supply is determined thereby from a measured heating time.

In EP 0 373 965, a method and a device for determining a gas or energy consumption from a corrected mass flow signal are disclosed. During the signal correction, the heat conductivity, specific heat capacity and density of the gas are taken into account. The corrected mass flow signal and hence gas or energy consumption signal is independent of the type of gas and in particular is identical for air, argon, helium, carbon dioxide, methane and propane. It is disadvantageous that a mass flow signal standardised in such a way is not sensitive to the heat value of a gas or gas mixture since combustible gases with different heat values (e.g. methane or propane) produce the same mass flow signals and even the same signals as non-combustible gases (e.g. helium, argon, carbon dioxide or air). 3 In the U.S. Pat. No. 5,311,447, a method and a device for combustion-less determination of the specific heat value of natural gas are disclosed. For this 5 purpose, specific heat value, density or proportion of inert gases are determined by empirical formulae from measured values of viscosity, heat conductivity, heat capacity, optical absorption, etc. The large measuring and computing complexity is disadvantageous 10 in quantitative measurement of a plurality of inde pendent gas type-dependent values and, in the case of combination thereof, with a volume flow measurement in a gas meter in order to determine a consumed quantity of energy.

In WO 01/18500, an improved mass flow measurement with two thermal CMOS anemometers is disclosed. On the static gas, measurements are made of heat conductivity in the case of a constant heat output and, in 20 the case of a pulsed heat output, of heat capacity, the gas is identified and, from the specific heat value thereof together with the mass flow measurement, the total calorific value of the gas is determined. The relatively large complexity when determin-25 ing the consumed quantity of energy from separate values of mass flow and specific heat value is in turn disadvantageous. In addition, the specific heat value for a sufficiently accurate determination of the energy supply must be measured continuously and 30 with great accuracy.

In the article by D. Hoburg and P. Ulbig, "Gesetz-liches Messwesen und Brennwertrekonstruktionssys-teme", Gas • Ergas 143 (2002) No. 1, calorific value 35 reconstruction systems for gas networks with differ ent supply calorific values are disclosed. By Simula tion of the natural gas flows in the mains system, with the assistance of measuring data such as temperature and pressure, the gas constitution at any points in the gas network can be calculated. In particular the delivery calorific value at the delivery point to the customer can be calculated dynamically from the supply calorific values, supply through-flows, delivery through-flows and further auxiliary values such as network pressures. Normal gas constitution data, which must be detected by measurement technology at the supply points, are calorific value, standard density, C02 content and H2 content. It is also disadvantageous that the geometry and topology of the network, in particular pipe roughnesses, are mostly inadequately known and the simulation calculation becomes altogether inaccurate. Also the result of the simulation calculation depends greatly upon the chosen pipe flow model and upon the computer power which is available.

REPRESENTATION OF THE INVENTION It is the object of at least preferred embodiments of the present invention to indicate a method and a device for determining a gas energy supply with improved accuracy, or to at least provide the public with a useful choice.

The invention resides in a first aspect in a method for measuring a gas supply by means of a gas meter which is disposed at a gas supply location of a gas supply network, the gas meter including a flow sensor, a measuring signal for a quantity consumption and/or energy consumption of the gas being determined by the flow sensor, the method comprising:(a) determining, using a computing means, a sensor error factor of the gas meter in order to detect deviations intellectual property office of n.z 3 1 JAN 2008 (followed by page 5a) between the consumption measured by the gas meter and the actual consumption, determining using a computing means, a consumption profile for the gas consumption, which profile is characteristic of the gas supply location, the sensor error factor and the consumption profile for an accounting period definable as a function of a common variable and calculating, using a computing means, a consumption-weighted correction factor relative to the accounting period by averaging the sensor error factor weighted with the consumption profile and, with the correction factor, the measuring signal is converted into an output value.

The invention resides in a second aspect in a method for measuring a gas supply, by means of a gas meter which is disposed at a gas supply location of a gas supply network, the gas meter including a flow sensor, the method comprising: (a) determining a measuring signal for a quantity consumption and/or energy consumption of the gas by the flow sensor, (b) determining a sensor error factor of the gas meter in order to detect deviations between the consumption measured by the gas meter and the actual consumption, (c) determining a consumption profile for the gas consumption, which profile is characteristic of the gas supply location, (d) the sensor error factor and the consumption profile for an accounting period are definable as a function of a common variable and (e) calculating a consumption-weighted correction factor relative to the accounting period by averaging the sensor error factor weighted with the consumption profile and, with the correction factor, the measuring signal is converted into an output value.

»TCU^r?TOPERTY- ofrce of m.2. 2 7 MAR 2008 I RECEIVE D 5a (followed by page 6) Preferably, the gas supply is measured in at least one of a private sector, a public sector, and an industrial sector.

The conversion can be implemented in the gas meter or outside it, e.g. at the gas network operator. The sensor error factor fi takes into account inherent, typically gas type-dependent measuring errors of the gas meter or flow sensor. The consumption profile li is intended to reproduce the consumption behaviour of the gas energy subscriber as realistically as possible. It can be given for flow rates in any units, e.g. volume flow, mass flow or gas energy flow. The correction factor F is normally calculated by multiplication or in a similarly operating manner by the measuring signals. The method and gas meter according to the invention has the substantial advantage that variations in the gas composition are weighted with the customer-specific consumption behaviour and are used only in such a customer-specific form for correction of the measuring signal Vs, Vns, Ms, Es. As a result, the accuracy of a gas volume, gas mass or gas energy measurement is significantly increased.

In one embodiment, the measuring signal is an operating volume signal Vs, standard volume signal VnSf gas 1311685 l.DOC intellectual property office of n.z 3 1 JAN 2008 mass signal Ms or energy signal Es measured by the gas meter and/or the output value is a supplied standard volume Vn, a supplied gas mass M or a supplied gas energy E.

In another embodiment, the averaging comprises summation and/or integration over the common variable of products which contain the sensor error factor and the consumption' profile, and/or the averaging is implemented taking into account a heat value profile Hi (or Hi') relative to the common variable. In particular, the averaging includes a suitable standardisation function.

The embodiment according to claim 6 part (a) has the advantage that a measuring signal can be added up in the gas meter over for example half a year or an entire year, read by the gas man or transmitted and corrected only subsequently with respect to variations in gas composition and in particular in heat value. The correction factor F can be determined by an independently implemented averaging, in particular a priori, simultaneously or a posteriori for measuring signal detection. Hence, in the case of non-registering gas meters, the time-averaged measuring signal can be corrected in a customer-specific manner with little complexity without heat value variations and/or gas load profiles requiring to be detected locally or transmitted to the gas supply location. The subsequent measuring signal correction can be implemented in principle also in the gas meter itself.

The embodiment according to claim 6 part (b)has the advantage that a measuring signal can detected during registering operation and converted or corrected immediately or with a slight time delay with a cur- intellectual property office of n.z. 31 JAN 2008 rently determined correction factor F. In the current correction factor F, for example measured or predicted values of the sensor error factor fi# of the consumption profile li and if necessary of the heat value Hi can be taken into account. As a result, a registering gas meter can be produced with the highest measuring accuracy. The current measuring signal correction can be implemented in the gas meter or outwith the gas meter.

The embodiments according to claims 8-10 have the advantage that, in the case of a known gas composition, the sensor error factor fi and, if required, the heat value Hi can be determined immediately.

The embodiment according to claims 11 and 12 have the advantage that the gas composition is already known to the operator or can be determined easily by the operator and/or can be calculated by means of known simulation models for gas flows in the network.

The embodiment according to claims 13 to 15 have the advantage that the sensor error factor fif the consumption profile li and if necessary the heat value Hi can be represented as a function of time or temperature and averaged together.

The embodiments according to claims 16 and 17 have the advantage that the local gas subscriber can choose that gas consumption or load profile li which can be determined easily and can be updated simply if necessary, which demands little computing complexity and in particular memory requirement and/or which has the greatest prediction force for the gas consumption to be expected. intellectual property office of n.z. 31 JAN 2008 RECEIVED 8 The embodiments according to claims 18 to 20 relate to concrete computer specifications for exact calculation of the correction factor F when using the gas meter as volume, gas mass or gas energy measuring device .

The embodiments according to claims 21 to 23 relate to calibration of the gas meter as energy measuring device, in particular an inherent dependency of the thermal flow sensor signal upon the heat value Hi being able to be taken into account in order to improve the accuracy of the gas energy measurement.

The invention resides in a third aspect in a gas meter for measuring a gas supply, the gas meter having a flow sensor and a measuring and evaluating unit for determining a measuring signal for a quantity and/or energy consumption of the gas, comprising: (a) computing means for determining and/or storing a sensor error factor of the gas meter and a consumption profile characteristic of the gas supply location and also for calculating a correction factor by weighted averaging of the sensor error factor with the consumption profile are present and (b) computing means for converting the measuring signal by means of the correction factor into an output value of the gas meter. Preferably, a data memory for storing the sensor error factor fi and the consumption profile li as a function of a common time variable and/or temperature variable are present and/or the computing means and/or the data memory are disposed outside the gas meter or in the gas meter. intellectual property office of n.z 31 JAN 2008 RECEIVED 9 Preferably, the gas supply is measured in at least one of a private sector, a public sector, and an industrial sector.

Preferably, the gas meter is disposed at a gas supply location of a gas supply network.

The embodiments according to claims 26 - 29 enable a particularly simple construction and operation of the gas meter as energy measuring device.

Further embodiments, advantages and applications of the invention are revealed in the dependent claims and also in the description and Figures which now follow.

BRIEF DESCRIPTION OF THE DRAWING There are shown: Fig. 1 in cross-section, a pipe with a flow, having a thermal gas meter with means for improved measuring signal correction; Fig. 2 schematically, a gas distribution network; Fig. 3 a load profile of a gas consumer at a gas supply location; and Fig. 4 measurement curves for natural gas for demonstrating a partially correlated behaviour of monthly average values of sensor signals of the thermal gas meter with heat values of natural gas.

In the Figures, the same parts are provided with the same reference numbers. 1311685_1.DOC intellectual property office of n.z 3 1 JAN 2008 n /"> I V! C F\ WAYS TO IMPLEMENT THE INVENTION Fig. 1 shows a gas meter 1 comprising a thermal flow or mass flow sensor la which comprises a sensor element la, which is disposed in a flow channel or pipe 2, and a measuring and evaluating unit 7. In the pipe 2 flows a gas 3b with a flow and velocity profile 4. The sensor element la is subjected to a flow velocity v to be measured. The through-flow sensor la comprises a heating element 6, a first temperature sensor 5a upstream and a second temperature sensor 5b downstream. From temperature signals Ti, T2 of the temperature sensors 5a, 5b, a mass flow or standard volume flow signal S can be determined in a known manner. The principal mode of operation is based on the fact that a temperature distribution through the flow 4, produced by the heating element 6, becomes asymmetric and a temperature difference Ti - T2 at the temperature sensors 5a, 5b is used as a measure of the flow velocity v or the mass flow dm/dT. The mass flow signal S is to a good approximation proportional to the temperature difference Ti - T2. In addition in the present case, energy signals Es are determined and output, by means of a first basic heat value factor Hch relative to a basic gas mixture, by the measuring means 7 from the mass flow signal S or in general sensor signal S of the through-flow sensor la. In this way, a calibration of the gas meter 1 as energy measuring device is achieved. The calibration as energy measuring device is disclosed in WO 01/96819 Al, the content of which is herewith introduced in the present disclosure in its entirety by reference. Likewise, the three articles cited therein relating to the CMOS anemometer by J. Robadey and F. Mayer et al. may be introduced here by reference. The CMOS 11 anemometer described there is particularly suitable as sensor element la of the through-flow sensor.

According to the invention, a typically gas type-dependent sensor error factor fi, fi', fi''/ fi'' ' and a customer-specific consumption profile li, li', Li is determined or detected by the gas meter 1, a correction factor F is calculated therefrom and, with this, a measuring signal Vs, Vns, Ms, Es of the gas meter 1, in particular an energy signal Es/ is converted into an output value Vn, M, E, in particular a gas energy E, with improved calibration accuracy. The method is represented in detail in the course of the description and in various embodiments.

Instead of the flow sensor la with two temperature sensors 5a, 5b and in particular instead of the CMOS anemometer la, also a thermal flow sensor can be used in general for the operability of the gas meter 1 as volume, mass or energy meter 1, in which flow sensor the gas 3b is guided via a sensor element which has a heating means for temperature change and a sensor means for determining its temperature, the flow-dependent temperature change in turn being a measure of the through-flow or mass flow. Alternatively, the thermal flow sensor la can also be operated with only one temperature sensor 5a which is disposed upstream. The method according to the invention can also be implemented with any non-thermal gas meter 1 which, upon a through-flow, e.g. a mass flow, delivers calibrated signals. In general, the mass flow dm/dt can be indicated in mass or, in the case of a constant gas type, in standard volume units, e.g. in kg/min or can be determined according to dm/dt=p*dV/dT by means of the density p from a volume flow dV/dT. 12 Fig. 2 shows a diagram of a gas supply network 11 with gas supply locations 12, consumers 13 and measuring points 15, in particular for flow measurement and if necessary pressure or temperature measurement. The distribution network 11 is controlled and monitored by a central office or by an operator 10. The gas supply location, at which a gas meter 1 according to the invention is installed, is designated for example with 14. A supplied gas composition 3a or a gas composition 3b present at the gas supply location 14 can be determined by an operator 10 of the gas supply network 11, for example from empirical values, measuring values, prognosis values or values of the gas quality derived therefrom. The gas composition 3b at the gas supply location 14 can also be calculated at least approximately from the supplied gas quality by means of simulation calculation for gas flows in the gas supply network 11. Methods for this purpose can be deduced for example from the initially mentioned article by D. Hoburg and P. Ulbig, which is introduced herewith in its entirety by reference.

Preferably, the gas meter 1 is operated in the conventional manner in a non-registering manner, is read now and again and subsequently the integral measuring signal Vs, Vns, Ms, Es is converted into the more precise output value Vn, M, E. The conversion can be implemented subsequently in the gas meter 1 or preferably outside of it, for example at the network operator 10.

The method can also be applied to a registering gas meter 1. For this purpose, a gas meter 1 comprises a receiving unit 9 for receiving heat value data of a gas composition 3b present at the gas supply location 14 from an external unit 10, in particular an opera- 13 tor 10 of the entire gas network 11 or of a partial network. The operator 10 can ascertain measuring data by himself or through external locations and use analysis means to determine the gas composition 3a.

He can deliver to the local gas meter 1 raw data or prepared data, in particular a specific heat value profile Hi, Hi', for the local gas composition 3b or the one present in the relevant sub-network. Calculation and data transmission to the gas meter 1 can be 10 repeated at prescribable time intervals. The reli ability of the energy measurement is significantly increased since, using global and local data, an improved heat value correction can be implemented. The global data relate to the gas supply and gas distri-15 bution in the network. They are present at the opera tor 10 and can be used in a manner known per se to determine a local gas composition 3b relating to the gas supply location 14. Data relating to the local gas consumption behaviour li, li', Li of the customer, 20 which can be detected by the gas meter 1, can be col lected directly in situ or be determined in another manner. By combining these data, the gas energy supply E from the energy measuring device 1 is determined with significantly improved accuracy. This com-25 bination of the data and the conversion of the meas uring signal Vs, Vns, Ms, Es to the more precise output value Vn, M, E can be implemented in the gas meter 1 or outwith the gas meter 1, for example at the network operator 10. Deviating from the representa-30 tion in Fig. 1, 9 then serves as transmission unit for transmitting the measuring signals Vs, Vns, Ms, E to the central office 10, where the computing units 7a, 7b and/or the data memory 7d are preferably present .

S 14 Fig. 3 shows a load profile of the gas consumer at the supply location 14. The consumption profile It, li', Li can be a gas quantity load profile 1 (T) relative to a standard volume Vn/ a gas mass load profile li' (T) relative to a gas mass M or a gas energy load profile Li (T) relative to a gas energy E. By way of example, a gas consumption profile 1 (t) is plotted e.g. in energy units per day (kWh/d) against a temperature T in °C. The gas consumption characteristic can be approximated for example by a function 1 (T) = (A+eB*T+c) _1+D, wherein A, B, C and D are determinable, consumer-specific parameters. Other functions or approximation formulae 1 (T) for approximation or prediction of the gas supply behaviour are also possible, similarly the tabular storage of support point values li with discreet temperature values Ti with i = integer index. The consumption profile li, li', Li can be determined globally for a section of the gas supply network 11 comprising the gas supply location 14 or locally for the gas supply location 14. The functional correlation 1 (T) or support point values li (Ti) can be obtained from empirical values, measuring values, prognosis values or values derived therefrom for a gas consumption to be expected at the gas supply location 14. The temperature variable T can describe an outside temperature or a temperature average value at the gas supply location 14. Alternatively, the load profile li, li', Li can be defined for a time variable, in particular dependent upon time of day, weekday, month or course of a year.

The sensor error factor fi, fi', fi'', fi''' and in particular a heat value or heat value profile Hi, Hi' can be determined from the gas composition 3a, 3b, for example by means of calibration tables. Advantageously, the gas composition 3a, 3b and the consump tion profile li, li', Li are known as a function of the common variables t, T. The sensor error factor fi, fi', fi'', fi''' and if necessary the heat value profile Hi, Hi' can also be given themselves directly as a function of the common variables t, T and thus can be correlated with the consumption profile li, li', Li.

In the following, embodiments for computing specifications are indicated for using the gas meter 1 as an improved volume, mass or energy measuring device. The calculation is implemented for example with support values or average values in a time interval indexed with i; instead of adding support point values, integrals of function values can also be formed over the common variable, e.g. time. There applies: with output value Vn = supplied standard volume (= standard volume added up over a specific time = integral of the standard volume flow rate for current gas composition 3a) and measuring signal Vs = operating volume added up in the period of time, K = correction factor F, li =Vni/Vn = gas quantity load profile relative to standard volume (standardisation e.g.: Vn,i = Vn, i.e. Hi li = 1) , fi = VSi/Vni = sensor error factor for operating volume measuring errors, Vsi = operating volume signal (indicated by gas meter 1, pressure- and temperature-dependent) and Vni = standard volume (actually supplied) in the time interval i. There is in fact Vn = Vs • K K = l/Zi (li • fi ) (El) (E2) Vs — Vsi — Vn • ^]i (li • fi ) = Vni • fi = li • fi *Vn (E3) (E4) If a standard volume signal Vns is detected by the gas meter 1 as measuring signal (= added-up standard volume measured actually over a specific time by the gas meter 1 = integral of the measured flow rate for current gas composition 3a) and is added up in the accounting period, then there applies Vn = Vns • K' (E10) K' = 1/Ei (li • fi') (E20) with K' = correction factor F, fi' = VnSi/Vni = sensor error factor for standard volume measuring errors, Vnsi = standard volume signal and Vnl - standard volume in the time interval i. There is in fact Vnsi = Vni • fi' = li • fi' • Vn (E30) vns = Si Vnsi = Vn • Si (li • fx') (E40) If a gas mass signal Ms is detected by the gas meter 1 as measuring signal and added up in the accounting period and a corrected gas mass M is calculated as output value, then there applies M = Ms • K" (Ell) K" = 1/Ei di' • fi") (E21) with K'' = correction factor F, li' = Mi/M = gas quantity load profile relative to gas mass, fi'' = MSi/Mi = sensor error factor for gas mass measuring errors, MSi = gas mass signal and Mi = gas mass in the time interval i. There is in fact Msi = Mi • fi" = li' • fi" • M (E31) Ms = Si Msl = M • Si di' • fi" ) (E41) 17 When using the gas meter 1 as gas energy measuring device 1, several formulations are also possible, a few of which are indicated subsequently by way of example. If an operating volume signal Vs is detected by the gas meter as measuring signal and added up in the accounting period and a corrected supplied gas energy E is calculated as output value, then there applies with Hgew,s = weighted specific heat value per standard volume = correction factor F, H± = heat value profile per standard volume, li = Vni/Vn = gas quantity load profile relative to standard volume Vn or Li = Ei/E = gas energy load profile relative to gas energy E, fi = VSi/Vni = sensor error factor for operating volume measuring errors, Vsi = operating volume signal, Vni = standard volume and Ei = gas energy in the time interval i. With (E4) there is of course on the one hand E = Ei Ei = Vs Si (Hi • li) /Si di • fi) (E52a) and on the other hand (E12) or (E22a) (E22b) Vni = Vn • li = Vs • li/Ei (li • fi) Ei = Hi • Vni (E32a) (E42a) Ei = E • Li = Hi • Vni Vsi = Vni • fi = E • Li • fi/Hi Vs = Si Vsi = E • Si (Li • fi/Hi) (E32b) (E42b) (E52b) 18 If a standard volume signal Vns is detected by the gas meter 1 as measuring signal and added up in the accounting period, then there applies E = Vns • Hgew,ns (E13) Hgew, ns = S i (Hi • li) /Si (li • fi') or (E23a) Hgew,ns = 1/Ei (Li • fi' /Hi) (E23b) with Hgew,ns = weighted specific heat value per stan-10 dard volume = correction factor F, Hi = heat value profile per standard volume, li = Vni/Vn = gas quantity load profile or Li = Ei/E = gas energy load profile, fi' = Vnsl/Vni = sensor error factor for standard volume measuring errors, Vnsi = standard volume signal 15 and Vni = standard volume in the time interval i. With (E40) there is of course on the one hand Vns = Vn • Si di • fi') (E40) Vni = Vn • li = Vns • li/S di # f i ' ) (E33a) Ei = Hi • Vni (E43a) E = Si Ei = Vns Si (Hi • li)/Si di • fi') (E53a) On the other hand there applies Ei = E • Li = Hi • Vni (E33b) vnsi = Vni • fi' = E • Li • fi' /Hi (E43b) Vns = Si Vnsi = E Si (Li • fi' /Hi) (E53b) If a gas mass signal Ms is detected by the gas meter 30 1 as measuring signal and added up in the accounting period, then there applies E = Ms • Hgew,M (E14) Hgew,M = S (Hi' • li')/Si di' • fi") or (E24a) Hgew,M = 1/Si (Li • fi' ' /Hi' ) (E24b) 19 with Hgew,M = weighted specific heat value per mass = correction factor F, Hi' = heat value profile per mass, li' = Mi/M = gas mass load profile relative to gas mass M, fi'' = Msi/Mi = sensor error factor for gas mass measuring errors, MSi = gas mass signal and Mi = gas mass in the time interval i. With (E41) there applies of course on the one hand Ms = Ei Msi = M • Ei di' • fi") (E41) Mi = M • li' = Ms • li'/Ei di' • fi") (E34a) Ei = Hi' • Mi (E44a) E = Ei Ei = Ms Ei (Hi' • li' ) /Ei di' • fi") (E54a) On the other hand there applies Ei = E • Li = Hi' • Mi (E34b) Msi = Mi • fi" = E • Li • fi' ' /Hi' (E44b) Ms = Ei MSi = E • Ei (Li • fi' ' /Hi' ) (E54b) If a gas energy signal Es is detected by the gas meter 1 as measuring signal and added up in the accounting period, then there applies E = Es • hgew (El5) hgew = Ei (Hi • li' ) /Ei (Hi • li • fi'") or (E25a) hgew = 1/Ei (Li • fi'") (E25b) with hgew = weighted heat value correction factor = correction factor F, Hi = Ei/Vni = heat value profile per standard volume, li = Vni/Vn = gas quantity load profile or Li = Ei/E = gas energy load profile, fi'" = ESi/Ei = sensor error factor for gas energy measuring errors, ESi = gas energy signal and Ei = gas energy in the time interval i. There applies in fact on the one hand Ei = Hi • Vnl = Vn • Hi • li Esi = Ei • fi'" = Vn • Hi • li • fi'" Es = Ei Esl = Vn Ei (Hi • li • fi'") E = Ei Ei = Vn Ei (Hi • li) (E35a) (E45a) (E55a) (E65a) E = Es • Ei (Hi • li) /Ei (Hi • li • fi'") (E66a) On the other hand, there applies For energy accounting, the gas energy E should be multiplied by the price per energy unit. This price can if necessary also be time-dependent, which in the case of the heat value weighting, in particular in the heat value correction factor hgew, can also be taken into account.

In the above-mentioned examples, the sensor error factor fi, fi', fi'' , fi"' is chosen without dimension. Further embodiments for determining correction factors F can be obtained as a result of the fact that other combinations of measuring signal and output value are chosen and the auxiliary values sensor error factor, consumption profile and if necessary heat value profile are suitably defined in order to combine together measuring signal and output value or their temporally averaged values. By way of example, dimension-associated sensor error factors can be introduced, e.g. fiv = VSi/Mi, in order, with a given dimensionless sensor error factor, to convert load profile, heat value profile and/or measuring signal, instead of to an output value, e.g. standard volume, to a different output value, e.g. gas mass. In addition, a conversion could be performed of an energy Ei — E • Li Esi = Ei • fi'" = E • Li • fi"') Es = Ei Esl = E Ei (Li • fi"') (E35b) (E45b) (E55b) 21 signal Es to a standard volume or to a gas mass M. Such and similar embodiments may herewith be disclosed jointly in an explicit manner.

The flow sensor la is preferably a thermal flow sensor la, with which a sensor signal S^ai calibrated to a flow rate is determined. In order to calibrate the gas meter 1 as energy measuring device 1, the calibrated sensor signal S^ai is calibrated using a basic heat value factor Hch for a basic gas mixture CH into the gas energy signal Es.

According to WO 01/96819 Al, there is effected in the thermal through-flow sensor la, in particular in the CMOS anemometer through-flow sensor la, an inherent automatic heat value tracking in the case of deviations of the current gas mixture 3b from the basic gas mixture CH. Since the inherent heat value tracking is incomplete, now, starting from the first energy calibration for the basic gas mixture CH, a second improved energy calibration is implemented according to the invention by means of the weighted heat value correction factor F = hgew.

For the mentioned gas energy measuring device 1 with thermal flow sensor la, the underlying measuring method is now described in more detail. According to WO 01/96819 Al, a sensor signal SN2 (previously S) for a calibration gas, typically nitrogen N2 or air, is determined and calibrated to an (uncorrected) mass flow signal Sm (previously S (d (VN2,n)/dt), d(VN2,n)/dt = standard volume flow for calibration gas). The calibration can be expressed by a sensor calibration curve F(SH2) for the calibration gas under normal conditions, Sm being proportional to F(Sn2) or simply Sm = F(SN2) . The mass flow signal Sm still depends 22 upon the type of gas. Hence, deviations of the mass flow signal Sm from an exact ideal value for a basic gas mixture, typically natural gas or in general a hydrogen mixture CH, are corrected by a signal con-5 version factor or sensor signal correction factor fu2- ch- Hence there applies Sm = Sm • fn2-ch with Sm = corrected mass flow signal. In the sense of this disclosure, Sm is equal to or proportional to the previously mentioned calibrated sensor signal Skai of the 10 flow sensor la. Likewise, the gas standard volumes Vns,i and Vns in the case of sufficiently constant gas quality, are equal to or proportional to the calibrated sensor signals Skai or average values of Skai in the associated time interval i. The calibrated sensor 15 signal Skai is therefore a measure of and in particu lar proportional to a through-flow rate of the gas composition 3b to be measured. Therefore Skai = Sm • fn2-ch can be written, a possibly necessary proportionality factor being taken into account in the sen-20 sor calibration curve F(SN2). Finally, an energy sig nal Es is determined by multiplication of the calibrated sensor signal Skai by a heat value Hch (calo-rimetric value per unit of the through-flow value, i.e. per standard volume or per mass) of the basic 25 gas mixture: Es = /Skai • Hch • dt = fN2-cH • Hch • /F(SN2) • dt or Es = Skai • Hch with Skai = averaged calibrated sensor signal.

According to WO 01/96819 Al or EP 1 227 305, intro-30 duced herewith in their entirety by reference, also suitable time average values can be used for the mentioned values Sn2, F(Sn2), fn2-ch and Hch and values derivable therefrom.

Fig. 4 shows how heat value variations up to a fraction are detected inherently from the sensor signals 23 Skai of the flow sensor la. This characteristic is known per se from WO 01/96819 Al and can be stored quantitatively in the gas meter 1 for example as sensor error factor fL' '' = Esi/Ei. The sensor error factor fi''' is therefore chosen to be proportional to the deviations between the inherently detected and the actual heat value variations of the gas composition 3b at the gas supply location 14 or as an average of these deviations. These deviations, i.e. the inherent heat value dependency of the energy signals Es relative to a basic gas mixture CH, are corrected in that the sensor error factor f''' in the correction factor F according to the invention is taken into account and the energy signals Es are calibrated by means of the correction factor F subsequently and/or offline to improved or corrected or actual gas energy output values E.

The invention also has a gas meter 1 for implementing the above-described method as subject. According to Fig. 1 and 2, the gas meter 1 is disposed at a gas supply location 14 of a gas supply network 11 and has a flow sensor la and a measuring and evaluating unit 7 for determining a measuring signal Vs, Vns, Ms, Es for a quantity and/or energy consumption of the gas 3a, the measuring and evaluating unit 7 having computing means 7a for determining and/or storing a sensor error factor fi, fi', fi'', fi''' of the gas meter 1 and a consumption profile li, li', Li characteristic of the gas supply location 14 and also for calculating a correction factor F by weighted averaging of the sensor error factor fi, fi', fi'', fi''' with the consumption profile li, li', Li, and the measuring and evaluating unit 7 has furthermore computing means 7b for converting the measuring signal Vs, Vns, Ms, Es by means of the correction factor F into an output value 24 Vn/ M, E of the gas meter 1. Preferably, the measuring and evaluating unit 7 comprises a data memory 7d for storing the sensor error factor fi, fi', fi'', fi''' and the consumption profile li, li', Li as a function of a common time variable and/or temperature variable T.

Advantageously, the flow sensor la is a thermal flow sensor la, in particular a CMOS anemometer la, with a heating wire 6 and temperature sensors 5a, 5b disposed upstream and downstream. The measuring and evaluating unit 7 has in particular means for calibration of the gas supply in energy units kW/h.

Furthermore, the measuring and evaluating unit 7 can comprise computing means 7c for determining a calibrated sensor signal Skai by means of re-evaluation of a calibration gas to a basic gas mixture CH and for determining a gas energy signal Es by means of multiplication of the calibrated sensor signal Skai by a basic heat value factor Hch- In particular, computing means 7a for determining and/or storing a sensor error factor fi'' ' for gas energy measurement is present for detection and correction of an inherent dependency of the calibrated sensor signal Skai of the through-flow sensor la upon heat value variations. The computing unit 7a, 7b, 7c and/or the data memory 7d can also be disposed outwith the gas meter 1.

The term "comprising" as used in this specification means "consisting at least in part of". When interpreting each statement in this specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. intellectual PHurchl. office of n.z. 3 1 JAN 2008 BcnElVED Reference number list 1 Gas meter la Thermal mass flow sensor, CMOS sensor lb Membrane 2 Flow channel, pipe 3a Gas composition in the gas network; natural gas 3b Gas composition at the supply loca-10 tion; natural gas 4 Flow profile 5a, 5b First, second temperature sensor, thermoelements 6 Heating element, heating wire 7 Measuring and evaluating unit 7a, 7b, 7c Computing means 7d Data memory 8 Signal output, display 9 Receiving unit, transmitting unit (op-20 tional) External unit, operator, central office 11 Gas supply network 12 Gas supply 25 13 Consumer 14 Gas supply location Flow measurement, measuring point of the operator CH Natural gas, basic gas mixture F (SN2) Sensor calibration curve fn2-ch Signal conversion factor fi, fi', fi'', fi''' Sensor error factor F Correction factor HCh Basic heat value factor for the basic gas mixture 26 Hi, Hi' Heat value, heat value profile of the gas composition Hgew,s/ Hgew,ns Weighted heat value per standard volume Hgew,m Weighted heat value per gas mass hgew Weighted heat value correction factor K, K', K'' Volume correction factor, mass correction factor li, li' , Li' ' Gas consumption profile, load profile S Sensor signal Sm Uncorrected mass flow or sensor signal SM Corrected mass flow signal for the basis gas mixture SN2 Calibration gas sensor signal Skai Calibrated sensor signal t Time variable T, Ti, T2 Temperatures v Flow velocity Vs, VnS/ Ms, Es Measuring signal Vn, M, E Output value i Index for time interval s Index for measuring signal 27

Claims (32)

WHAT WE CLAIM IS:

1. Method for measuring a gas supply, by means of a gas meter which is disposed at a gas supply location of a gas supply network, the gas meter including a flow sensor, a measuring signal for a quantity consumption and/or energy consumption of the gas being determined by the flow sensor, the method comprising: (a) determining, using a computing means, a sensor error factor of the gas meter in order to detect deviations between the consumption measured by the gas meter and the actual consumption, (b) determining, using a computing means, a consumption profile for the gas consumption, which profile is characteristic of the gas supply location, (c) the sensor error factor and the consumption profile for an accounting period definable as a function of a common variable and (d) calculating, using a computing means, a consumption-weighted correction factor relative to the accounting period by averaging the sensor error factor weighted with the consumption profile and, with the correction factor, the measuring signal is converted into an output value.

2. Method for measuring a gas supply, by means of a gas meter which is disposed at a gas supply location of a gas supply network, the gas meter including a flow sensor, the method comprising: (a) determining a measuring signal for a quantity consumption and/or energy consumption of the gas by the flow sensor, 1311685_1.DOC intellectual property office of n.z. 2 7 MAR 2008 RECEIVED 28 (b) determining a sensor error factor of the gas meter in order to detect deviations between the consumption measured by the gas meter and the actual consumption, (c) determining a consumption profile for the gas consumption, which profile is characteristic of the gas supply location, (d) the sensor error factor and the consumption profile for an accounting period are definable as a function of a common variable and (e) calculating a consumption-weighted correction factor relative to the accounting period by averaging the sensor error factor weighted with the consumption profile and, with the correction factor, the measuring signal is converted into an output value.

3. The method of claim 1 or 2, wherein the gas supply is measured in at least one of a private sector, a public sector, and an industrial sector.

4. Method according to any one of the preceding claims, wherein: (a) the measuring signal is an operating volume signal, standard volume signal, gas mass signal or energy signal measured by the gas meter and/or (b) the output value is a supplied standard volume, a supplied gas mass or a supplied gas energy, and/or (c) the output value is calculated by multiplication of the measuring signal by the correction factor. intellectual property office of n.z. 2 7 MAR 2808 REC EIV E D 29

5. Method according to any one of the preceding claims, wherein (a) the averaging comprises summation and/or integration over the common variable of products which contain the sensor error factor and the consumption profile, and/or (b) the averaging is implemented taking into account a heat value profile relative to the common variable, and/or (c) the averaging includes a suitable standardisation function.

6. Method according to any one of the preceding claims, wherein (a) the measuring signal, in non-registering operation, is added up by the gas meter over a long accounting period and subsequently converted with the correction factor outside the gas meter or in the gas meter or (b) the measuring signal, in registering operation, is currently determined by the gas meter and is converted with a currently determined correction factor in the gas meter or outside the gas meter.

7. Method according to claim 6, wherein the measuring signal is added up over a short period.

8. Method according to any one of the preceding claims, wherein (a) the sensor error factor is determined from a gas consumption, and (b) the gas composition is known as a function of the common variable. |ntf"pctual property office of n.z. 1311685 l.DOC 31 JAN RECEIVED 30

9. Method according to claim 8, wherein a heat value or heat value profile is determined from a gas composition.

10. Method as claimed in claim 8, wherein the sensor error factor is determined by means of calibration tables.

11. Method according to any one of the preceding claims, wherein (a) a supplied gas composition or a gas composition present at the gas supply location is determined by an operator of the gas supply network, and/or (b) the gas composition at the gas supply location is calculated at least approximately from the supplied gas quality by means of simulation calculation for gas flows in the gas supply network.

12. Method as claimed in claim 11, wherein the supplied gas composition is determined from empirical values, measuring values, prognosis values or values of the gas quality derived therefrom.

13. Method according to any one of the preceding claims, wherein the common variable is a time variable, or a temperature.

14. Method as claimed in claim 13, wherein the time variable is a time of day, a week day, a month, or a course of a year.

15. Method as claimed in claim 13, wherein the temperature is an outside temperature profile or a 1311685J .DOC intellectual property office of n.z. 3 1 JAN 2008 RECEIVED 31 temperature average value at the gas supply location relative to the accounting period.

16. Method according to any one of the preceding claims, wherein (a) the consumption profile is a gas quantity load profile relative to a standard volume, a gas mass load profile relative to a gas mass or a gas energy load profile relative to a gas energy, and/or (b) the consumption profile is indicated by an approximation formula or by support values.

17. Method according to any one of the preceding claims, wherein (a) the consumption profile is determined globally for a section of the gas supply network comprising the gas supply location or locally for the gas supply location, and/or (b) the consumption profile is produced from empirical values, measuring values, prognosis values or values of the gas consumption at the gas supply location derived therefrom.

18. Method according to any one of the preceding claims, wherein (a) the output value is Vn = Vs • K, wherein Vn = supplied standard volume and Vs = operating volume signal added up in the accounting period, K = 1/Zi (li • fi) = correction factor F, li = Vni/Vn = gas quantity load profile relative to standard volume, fi = Vgi/Vni = sensor error factor for operating volume measuring errors, Vsi = operating volume signal and Vni = standard volume in the time interval i, or 1311685_1.DOC intellectual property office of n.z. 31 JAN 2008 dcociupd 32 (b) the output value is Vn = Vns • K' , wherein Vn = supplied standard volume and Vns = standard volume signal added up in the accounting period, K' = 1/Ei (li * fi' ) = correction factor F, li = Vni/Vn = gas quantity load profile relative to standard volume, fi' = Vnsi/Vni = sensor error factor for standard volume measuring errors, Vnsi = standard volume signal and Vni = standard volume in the time interval i, or (c) the output value M = Ms • K' ' , wherein M = supplied gas mass and Ms = gas mass signal added up in the accounting period, K' ' = 1/Si (li' • fi' ' ) = correction factor, li' = Mi/M = gas quantity load profile relative to gas mass, fi' ' = MSi/Mi = sensor error factor for gas mass measuring errors, MSi = gas mass signal and Mi = gas mass in the time interval i.

19. Method according to any one of the claims 1 to 17, wherein (a) the output value is E = Vs • HgeW;S or E = Vns * HgeW)ns, wherein Ei = supplied gas energy, Vs = operating volume signal added up and Vns = standard volume signal added up in the accounting period, wherein the correction factor F is a weighted specific heat value per standard volume HgeW/s = Si (Hi * li) /Si (li * -^i) t HgeW/s = 1/Sl (Li * fi/Hi) , HgeW/ns = Ei (Hi • li) /El (li • fi' ) or Hgew, ns = 1/Ei (Li * fi' /Hi) with Hi = heat value profile per standard volume, li = Vni/Vn = gas quantity load profile relative to standard volume Vn or Li = E±/E = gas energy load profile relative to gas energy E, fi = Vsi/Vni = sensor error factor for operating volume measuring errors or fi' = Vnsi/Vni = sensor error factor for standard volume measuring errors- v~- = 1311685 l.DOC intellectual property OFFIOF OF N 7 3 t JAN 2008 RECEIVED 33 operating volume signal, Vnsi = standard volume signal, Vni = standard volume and Ei = gas energy in the time interval i, or (b) the output value is E = Ms • Hgew,m, wherein E = supplied gas energy and Ms = gas mass signal added up in the accounting period, wherein the correction factor F is a weighted specific heat value per mass Hge„/M = Ei (Hi' * li')/Si (li' * fi'' ) , or Hgew,M = 1/Ei (Li • fi''/Hi') with Hi' = heat value profile per mass, li' = Mi/M = gas mass load profile relative to gas mass M, fi' ' = MSi/Mi = sensor error factor for gas mass measuring errors, MSi = gas mass signal and M± = gas mass in the time interval i.

20. Method according to any one of the claims 1 to 17, wherein the output value E = Es • hgew, wherein E = supplied gas energy and Es = gas energy signal added up in the accounting period, wherein the correction factor F is a weighted heat value correction factor hgew = Ei (Hi • li) /£i (Hi • 1± • fi" ' ) or hge„ = l/£i (Li • fi'' ' ) or hge„ = 1/Zi (Li • fi' '') with Hi = heat value profile per standard volume, li = Vni/Vn = gas quantity load profile relative to standard volume Vn or Li = Ei/E = gas energy load profile relative to gas energy E, fi' ' ' = ESi/E sensor error factor for gas energy measuring errors, Esi = gas energy signal and Ei = gas energy in the time interval i.

21. Method according to claim 20, wherein (a) the flow sensor is a thermal through-flow sensor, with which a sensor signal calibrated to a through-flow rate is determined, and 1311685_1.DOC intellectual property office of n.z. 31 JAN 2008 34 (b) in order to calibrate the gas meter as energy measuring device, the calibrated sensor signal is calibrated using a basic heat value factor for a basic gas mixture into the gas energy signal.

22. Method according to claim 21, wherein for the calibration of the gas meter as energy measuring device, the method further comprises (a) determining calibration gas sensor signals for the flow rate of a calibration gas and storing the calibration gas sensor signals in the form of a sensor calibration curve in the gas meter and (b) obtaining the calibration sensor signal by multiplying the sensor calibration curve by a signal conversion factor, and determining the gas energy signal from the latter by multiplying by the basic heat value factor.

23. Method according to claim 21 or claim 22, further comprising (a) inherently detecting heat value deviations up to a fraction from the calibrated sensor signals of the flow sensor, and (b) detecting deviations between the inherently detected and the actual heat value variations of the gas composition at the gas supply location by means of the sensor error factor for gas energy measuring errors and correcting the deviations during the conversion of the gas energy signal into the gas energy.

24. Gas meter for measuring a gas supply, the gas meter having a flow sensor and a measuring and evaluating unit for determining a measuring signal 1311685_1.DOC 35 for a quantity consumption and/or energy consumption of the gas, comprising (a) computing means for determining and/or storing a sensor error factor of the gas meter and a consumption profile characteristic of the gas supply location and also for calculating a correction factor by weighted averaging of the sensor error factor with the consumption profile, and (b) computing means for converting the measuring signal by means of the correction factor into an output value of the gas meter.

25. Gas meter according to claim 24, wherein the gas meter is for measuring a gas supply in at least one of a private sector, a public sector, and an industrial sector.

26. Gas meter according to claim 24 or claim 25, further comprising (a) a data memory for storing the sensor error factor and the consumption profile as a function of a common time variable and/or temperature variable, and/or (b) wherein the computing means and/or a data memory are disposed outside the gas meter or in the gas meter.

27. Gas meter according to any one of claims 24 to 26, wherein (a) the flow sensor is a thermal flow sensor, with a heating wire and temperature sensors disposed upstream and downstream, and/or (b) the measuring and evaluating unit has means for calibration of the gas supply in energy units. intellectual property office of n.z. 31 JAN 2008 1311685_1.DOC RECEIVED 36

28. Gas meter according to claim 27, wherein the thermal flow sensor is a CMOS anemometer.

29. Gas meter according to any one of claims 24 to 27, wherein (a) the measuring and evaluating unit has computing means for determining a calibrated sensor signal by means of re-evaluation of a calibration gas to a basic gas mixture and for determining a gas energy signal by means of multiplication of the calibrated sensor signal by a basic heat value factor, (b) computing means for determining and/or storing a sensor error factor for gas energy measurement are present for detection and correction of an inherent dependency of the calibrated sensor signal of the flow sensor upon heat value variations.

30. A method as claimed in claim 1 or 2 and substantially as herein described with reference to any embodiment disclosed.

31. A gas meter as claimed in claim 24 and substantially as herein described with reference to any embodiment disclosed.

32. A gas meter for measuring a gas supply substantially as herein described with reference to any embodiment shown in the accompanying drawings. EMS-PATENT AG 1311685_1.DOC intellectual property office of n.z. 31 JAN 2008