Method for improving measurement accuracy of coal gas pipe network

Abstract

The application discloses a coal gas pipe network measurement precision improving method, which comprises the following steps: step one, improving instrument measurement precision, wherein the measurement precision of a first-level measurement device in the coal gas pipe network is not lower than 1 level, and the measurement precision of a second-level measurement device in the coal gas pipe network is not lower than 0.2 level; and step two, performing temperature and pressure compensation on flow measurement, wherein when flow measurement is performed, the measured flow value is converted into a flow value under corresponding standard condition according to the actual temperature and pressure during measurement; the first-level measurement device is a device directly used for performing flow measurement, and the second-level measurement device is other auxiliary device used in cooperation with the first-level measurement device, wherein the second-level measurement device comprises a differential pressure transmitter and a power distributor. The application improves the measurement precision of the system, calculates parameters according to process conditions, checks the measurement system, and ensures the measurement precision. The application modifies the calculation of professional formula through temperature and pressure compensation, and ensures the measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of gas pipeline network measurement technology, and more specifically, to a method for improving the measurement accuracy of gas pipeline networks. Background Technology

[0002] The mixed gas is made by mixing blast furnace gas, coke oven gas and natural gas. After being mixed in a certain proportion by a pressurization station and a mixing station, the gas components are sent to the gas pipeline network, where a certain number of users and venting systems are connected.

[0003] The production and use of mixed gas includes both production parameters (production level) and consumption parameters (use level). Regarding production parameters: the production corresponding to the pipeline mixing consists of eight primary metering units: blast furnace gas, coke gas, and natural gas from blending station #1; blast furnace gas, coke gas, and natural gas from blending station #2; coke gas from blending station #3; and externally supplied converter gas. Regarding consumption parameters: the consumption of pipeline users consists of dozens of secondary metering units from large, medium, and small bar mills, forging plants, and steel pipe plants. The amount of venting ensures the safe operation of the pipeline network. The ratio of consumption parameters to production parameters is the consumption-to-production ratio, i.e.: Consumption-to-production ratio M = (several consumption units + two venting units) / eight production units. Taking 51 secondary meters, 2 release quantities, and 8 primary meters as an example, the consumption-to-production ratio M = (h1 + h2 + h3 ... + h51 + h52 + h53) / (c1 + c2 ... + c7 + c8), where M is the consumption-to-production ratio, c1 to c8 are the 8 production quantities, h1 to h51 are the 51 user consumption quantities, and h52 to h53 are the 2 release consumption quantities.

[0004] In practical production and applications, gas flow measurement elements are generally orifice plates, V-tube manifolds, V-cones, etc. After pressure tapping, a differential pressure transmitter is used for measurement. The output current signal of the differential pressure transmitter is split into two by a distributor: one path goes to the PLC, and the other goes to the energy center. Statistical surveys have found that due to the large number of metering points on a pipeline network, the measurement system at each metering point has a certain degree of error. After the errors accumulate, the production-to-consumption ratio fluctuates significantly, affecting cost settlement. For example, inaccurate measurements can lead to large discrepancies between production and consumption, causing metering disputes, resulting in economic disputes among multiple downstream users, and also posing production safety hazards.

[0005] After investigation and visits by technical personnel, the defects and shortcomings of the existing technology were summarized as follows: Due to the large number of flow measurement points on the pipeline network, taking the above embodiment as an example, there are a total of 61 measurement points (51 secondary meters, 2 venting points, and 8 primary meters). The large number of measurement points and the potential for measurement errors at each point result in a large total measurement error after the accumulation of errors. According to the actual measurement statistics of a certain instance, the production-to-consumption ratio was only about 94%, and 6% of the gas produced was not settled, affecting the income of the gas production unit and also affecting the balance and safety of the pipeline network.

[0006] The main reasons for the above problems are:

[0007] 1. Measurement error of hardware equipment:

[0008] There are many manufacturers of equipment related to predictive quantities used in gas flow measurement, such as orifice plates, V-cones, differential pressure transmitters, and distributors. Each manufacturer has different execution standards and product accuracy. For example, differential pressure transmitters might use Yokogawa EJA or Rosemount 3051 products, while distributors might use Ubisoft or Kingbow products. Generally, the accuracy of measuring elements is 1.5 class, differential pressure transmitters are 0.5 class, and distributors are 0.5 class, with varying accuracy levels.

[0009] The production capacity consists of 8 flow systems, therefore the production error is: The consumption consists of 53 flow systems, therefore the consumption error is... Total systematic error in mixed gas measurement Because both instruments and measurement systems have errors, the mixed gas system has a larger error margin.

[0010] 2. Due to the properties of the gas:

[0011] Coal gas is a gas and is compressible. Due to this compressibility, the parameters calculated by the measurement system will deviate from the actual parameters. Furthermore, coal gas is affected by temperature and unit load. When the air temperature is between -10℃ and 40℃, and the medium temperature is between 0℃ and 60℃, the pressure of the mixed coal gas is generally around 12 kPa. If the downstream unit load, start-up / shutdown, or calorific value of the coal gas changes, the coal gas pressure will also change accordingly, varying from 5 kPa to 22 kPa. These pressure variations will also cause measurement errors and significantly affect the flow rate.

[0012] 3. Reasons for errors between professional formulas and standard formulas:

[0013] The production of gas from blast furnaces #1 and #2 is high, resulting in significant measured values ​​and a substantial impact on the entire pipeline system. Primary elements utilize V-bar meters for measurement, while the original energy center used a standard formula. The failure to use the dedicated formula provided by Viagra, coupled with instrument measurement errors and temperature and pressure compensation, often resulted in a production-to-consumption ratio exceeding 100% or being very low.

[0014] 4. Other reasons:

[0015] Moisture, dust, and straight sections of the measuring pipe can also affect measurement accuracy. Summary of the Invention

[0016] (a) Technical issues

[0017] In conclusion, improving the measurement accuracy of gas pipeline networks has become a problem that urgently needs to be solved by those skilled in the art.

[0018] (II) Technical Solution

[0019] To achieve the above objectives, the present invention provides the following technical solution:

[0020] This invention provides a method for improving the measurement accuracy of gas pipeline networks. The method includes:

[0021] Step 1: Improve the measurement accuracy of instruments. Specifically, the measurement accuracy of primary measuring equipment in the gas pipeline network shall not be lower than Class 1, and the measurement accuracy of secondary measuring equipment in the gas pipeline network shall not be lower than Class 0.2.

[0022] Step 2: Perform temperature and pressure compensation for flow measurement. When measuring flow, convert the measured flow value into the corresponding standard condition flow value based on the actual temperature and pressure at the time of measurement.

[0023] The primary measuring device is the device used directly for flow measurement, and the secondary measuring device is other auxiliary equipment used in conjunction with the primary measuring device. The secondary measuring device includes differential pressure transmitters and distributors.

[0024] Preferably, in the gas pipeline network measurement accuracy improvement method provided by the present invention, when the calculation formula used for flow measurement in step two is a general formula, the following formula is adopted:

[0025]

[0026] Perform compensation calculations;

[0027] Where FlowTP is the actual flow rate, Fmax is the maximum flow rate measured, DPin is the instantaneous flow input value, DPScale is the differential pressure signal range, Td is the design temperature, Pd is the design pressure, Pr is the operating process pressure, and Tr is the operating process temperature.

[0028] Preferably, in the gas pipeline measurement accuracy improvement method provided by the present invention, when the calculation formula used for flow measurement in step two is the V-bar flow measurement special formula, the V-bar flow measurement special formula is:

[0029] Where Qv is the flow output, Ci is the flow coefficient, hw is the differential pressure input, Zf is the temperature coefficient, Pf is the input gauge pressure, and Tf is the input temperature.

[0030] Preferably, in the gas pipeline measurement accuracy improvement method provided by the present invention, when using the special formula for V-bar flow metering, temperature and pressure compensation is applied. The formula is calculated as follows:

[0031]

[0032] Where FlowTP is the actual flow rate, Fmax is the measured maximum flow rate, Pr is the operating process pressure, Tr is the operating process temperature, Pd is the design pressure, and Td is the design temperature.

[0033] Preferably, the method for improving the measurement accuracy of gas pipeline networks provided by the present invention further includes step three: adding measurement overflow and small signal correction;

[0034] Measurement overflow correction is as follows: when the measured value of a primary measuring device exceeds the upper limit of the measuring range of that primary measuring device, the portion exceeding the range is deducted.

[0035] The small signal adjustment is as follows: when the measured value of the primary measuring device is not greater than the lower limit of the range of the primary measuring device, the measured value is reduced and cut off.

[0036] Preferably, in the gas pipeline measurement accuracy improvement method provided by the present invention, the amount of small signal trimming is no more than 2% of the total signal.

[0037] (III) Technical Effects

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] This invention provides a method for improving the measurement accuracy of gas pipeline networks. The method includes: Step 1, improving the measurement accuracy of instruments, wherein the measurement accuracy of primary measuring equipment in the gas pipeline network is not lower than level 1, and the measurement accuracy of secondary measuring equipment in the gas pipeline network is not lower than level 0.2; Step 2, performing temperature and pressure compensation on flow measurement, converting the measured flow value into a flow value under corresponding standard conditions based on the actual temperature and pressure during measurement; wherein the primary measuring equipment is directly used for flow measurement, and the secondary measuring equipment is other auxiliary equipment used in conjunction with the primary measuring equipment, including differential pressure transmitters and distributors. Through the above method design, this invention improves the measurement accuracy of the system. By modifying the equipment to select higher-precision equipment and calculating parameters according to process conditions, the measurement system is calibrated to ensure measurement accuracy. Furthermore, this invention overcomes the influence of process changes on flow measurement by performing temperature and pressure compensation and converting volumetric flow rate to standard flow rate, and corrects the calculation of professional formulas to ensure measurement accuracy. This invention aims to identify the impact of external factors on flow measurement, overcome these impacts through technical means and calculations, and improve the production-to-consumption ratio by approximately 4% through a series of parameter corrections, demonstrating good results. Attached Figure Description

[0040] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0041] Figure 1 These are commonly used flow data acquisition and compensation formulas in the embodiments of this invention;

[0042] Figure 2 The formula for measuring the velibar in this embodiment of the invention;

[0043] Figure 3 The formula for the compensation measurement of the virgin bar in this embodiment of the invention;

[0044] Figure 4 This is the formula for measuring overflow and small signal correction in the embodiments of the present invention. Detailed Implementation

[0045] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. Indeed, those skilled in the art will recognize that modifications and variations can be made to the invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the invention encompass such modifications and variations falling within the scope of the appended claims and their equivalents.

[0046] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0047] This invention provides a method for improving the measurement accuracy of gas pipeline networks. The method includes three steps, as follows.

[0048] Step 1: Improve the measurement accuracy of the instrument.

[0049] The first step in this method is to appropriately replace and adjust the flow measurement equipment used in the pipeline network. Specifically, this involves adjusting the model of the flow measurement equipment (mainly adjusting its measurement range) and improving the measurement accuracy of both the primary and secondary measuring devices. Specifically, the measurement accuracy of the primary measuring devices in the gas pipeline network should be no less than Class 1, and the measurement accuracy of the secondary measuring devices should be no less than Class 0.2. The primary measuring devices are those directly used for flow measurement (e.g., orifice plates, V-cones, and Viagra), while the secondary measuring devices are other auxiliary equipment used in conjunction with the primary measuring devices. The secondary measuring devices include differential pressure transmitters and distributors.

[0050] Step 2: Perform temperature and pressure compensation on the flow measurement.

[0051] During flow measurement, the measured flow value is converted into a flow value under corresponding standard conditions based on the actual temperature and pressure at the time of measurement. The signal obtained from the flow measurement equipment is an analog signal, which is converted into an electronic signal before being used in calculations and finally displayed digitally. Since coal gas is a gas, its volume changes due to temperature and pressure. These volume changes directly affect flow measurement (for example, if the temperature at the user end decreases and the pressure increases, the coal gas volume compresses, and the total flow rate at the user end will always be less than the output flow rate from the producer). Therefore, this invention incorporates temperature and pressure compensation for flow measurement.

[0052] Specifically, in step two, when the calculation formula used for flow measurement is a general formula, the following formula is adopted: Compensation calculations are performed. Here, FlowTP is the actual flow rate, Fmax is the measured maximum flow rate, DPin is the instantaneous flow input value, DPScale is the differential pressure signal range, Td is the design temperature, Pd is the design pressure, Pr is the operating process pressure, and Tr is the operating process temperature.

[0053] Furthermore, in step two, when the calculation formula used for flow measurement is the specific formula for V-Bar flow measurement, the specific formula for V-Bar flow measurement is: Where Qv is the flow output, Ci is the flow coefficient, hw is the differential pressure input, Zf is the temperature coefficient, Pf is the input gauge pressure, and Tf is the input temperature.

[0054] Furthermore, when using the specific formula for V-bar flow metering, this invention also requires temperature and pressure compensation, calculated as follows: Where FlowTP is the actual flow rate, Fmax is the measured maximum flow rate, Pr is the operating process pressure, Tr is the operating process temperature, Pd is the design pressure, and Td is the design temperature.

[0055] Step 3: Add measurement overflow and small signal correction.

[0056] Measurement overflow correction is as follows: when the measured value of a primary measuring device exceeds the upper limit of the measuring range of that primary measuring device, the portion exceeding the range is deducted.

[0057] Small signal trimming is performed as follows: when the measured value of the primary measuring device is not greater than the lower limit of the measuring range of that primary measuring device, the measured value is removed. Furthermore, the removal amount for small signal trimming is no more than 2% of the total signal quantity.

[0058] One specific embodiment of the present invention is as follows.

[0059] 1. The parameters of the gas pipeline production instrument are as follows:

[0060] 1a. Production process parameters:

[0061] The blast furnace gas flow measurement element at the No. 1 mixing station is an integrated tube flow meter with a range of (0-270) Pa / 135000 m³. 3 / h;

[0062] The blast furnace gas flow measurement element at mixing station #2 is a V-bar, with a range of (0-219) Pa / 150000 m³. 3 / h;

[0063] The coke oven gas flow measurement element at mixing station #1 is a V-cone flow meter with a range of (0-2.5) kPa / 30000 m³. 3 / h;

[0064] The coke oven gas flow measurement element at the No. 2 mixing station is a V-cone flow meter with a range of (0-4) kPa / 32000 m³. 3 / h;

[0065] The coke oven gas flow measurement element at the No. 3 mixing station is a V-cone flow meter with a range of (0-100) Pa / 3000 m³. 3 / h;

[0066] The converter gas measuring element is a V-cone flow meter with a range of (0-1.6) kPa / 55000 m³. 3 / h;

[0067] The natural gas measuring element at the No. 1 mixing station is a V-cone flow meter with a range of (0-2500) Pa / 13000 m³. 3 / h;

[0068] The natural gas measuring element at the No. 2 mixing station is an annular orifice plate with a measuring range of (0-4000) Pa / 10000 m³. 3 / h.

[0069] 1b. Consumption process parameters:

[0070] It consists of 53 secondary metering points, designed according to the equipment model (furnace type and size) of each user point, with a consumption range from 500 to 50,000 m³. 3 / h.

[0071] 2. Improve instrument measurement accuracy:

[0072] 2a. Replace with equipment that has higher measurement accuracy:

[0073] The primary components have an accuracy of Class 1, the differential pressure transmitter has an accuracy of Class 0.075, and the distributor has an accuracy of Class 0.2. The accuracy has been improved from 1.66 to 1.02, an improvement of 0.64. Due to the large production volume, the error has been reduced significantly after the accuracy improvement.

[0074] For example: blast furnace gas flow measurement at mixing station #2: 150,000 m³ 3 / h, accuracy improved by ±0.64, measurement accuracy improved by ±96000m 3 / h.

[0075] 2b. Flow calculation is corrected:

[0076] The measured components were analyzed, and the calculations were recalculated based on the mixed gas composition. The instrument system was adjusted according to the new parameters and calibrated to ensure that the instrument was within the system error range. This invention, through equipment modification at 61 measuring points and parameter correction of process conditions such as composition, completed the system calibration at 61 points, which can improve the overall production-to-consumption ratio by about 1.9%.

[0077] 3. Flow measurement pressure compensation:

[0078] An investigation was conducted at each measuring point within the mixed gas pipeline network. Existing pressure measurements were augmented with additional distributors, splitting the signal into two paths, one of which was connected to the energy center. Pressure measuring point parameters were verified to determine the pressure range. Compensation programming was performed based on the design pressure values ​​from the orifice plate calculations. After commissioning, consumption increased by 3500 m³ / h more than production. 3 With a flow rate of approximately / h, after compensation, the gas consumption-to-production ratio increased from 96% to approximately 99%, an increase of about 3%.

[0079] 4. Temperature compensation for flow measurement:

[0080] Where process conditions permit, temperature measuring points will be added to the pipeline and converted to automatic compensation. For pipelines without measuring points, fixed compensation will be implemented. When weather temperatures fluctuate significantly, measurements will be taken again, and the fixed compensation values ​​will be adjusted accordingly. After compensation, the consumption will be reduced by 4800m³. 3 With a flow rate of approximately / h, after temperature compensation, the gas consumption-to-production ratio was reduced from approximately 99% to 97%, a decrease of about 2%.

[0081] 5. Change the professional formula:

[0082] In existing technology, the original PLC and energy center used a general formula for flow measurement. This time, the flow calculation for the V-bar, which has a large flow range, has been changed to a V-bar-specific formula, and the temperature and pressure compensation formula for the V-bar has also been replaced. Calculations show that the original general formula measures 138090 m³ / h. 3 The blast furnace gas flow rate of the No. 2 mixing station, calculated using a specific formula, is 131065 m³ / h. 3 / h, through system verification, the professional formula is more accurate, and the accumulated data has a smaller error compared with the theoretical calculation data.

[0083] 6. The Energy Center has added measurement overflow and small signal correction:

[0084] During measurement, sometimes the instrument reading exceeds 100%. After inspection, it is found that the problem is not with the measuring range, but rather caused by external interference or other reasons. Therefore, the portion exceeding 100% of the measuring range can be deducted. Sometimes, due to zero drift, temperature drift, or other issues with the current of differential pressure transmitters, small signals may be generated. These small signals should be cut off and controlled within 2%.

[0085] After the above adjustments, the list of production-consumption ratios before and after the modification is as follows:

[0086]

[0087] By improving the accuracy of instrument measurements, compensating for pressure and temperature in flow measurements, changing professional formulas, and adding measurement overflow and small signal corrections at the energy center, the pipeline network is in good balance, with the production-to-consumption ratio generally between 96% and 99.5%, averaging 98.14%, which is about 4% higher than before. This better meets the cost settlement requirements while also ensuring the calorific value requirements of the mixed gas and the safety of the pipeline network.

[0088] Based on the above design, this invention improves the system's measurement accuracy. By modifying the equipment to select higher-precision devices and calculating parameters according to process conditions, the measurement system is calibrated to ensure measurement accuracy. Furthermore, this invention overcomes the influence of process variations on flow measurement by performing temperature and pressure compensation and replacing volumetric flow rate with standard flow rate. The calculation of the professional formula is also corrected to ensure measurement accuracy. To identify the influence of external factors on flow measurement, this invention overcomes these influences through technical means and calculations, and through a series of parameter corrections, the production-to-consumption ratio is improved by approximately 4%, demonstrating good results.

[0089] Based on the above embodiments, the actual operation of the present invention is as follows:

[0090] Primary measuring elements include annular orifice plates, V-cones, integrated measuring tube flow meters, and V-bars, while secondary elements are differential pressure transmitters from Yokogawa Instruments or E+H manufacturers, with an accuracy of 0.5 class.

[0091] 1. Temperature and pressure compensation are as follows:

[0092] When designing a throttling device, calculations are performed based on certain pressures and temperatures. In actual applications, when process pressures and temperatures change, the volume of the gas also changes. Since the flow rate calculation is designed and calibrated according to the gas volume flow rate under standard conditions, temperature compensation and pressure compensation are necessary. The significance of temperature and pressure compensation is to convert the results measured under non-standard conditions into the corresponding flow rate values ​​under standard conditions, ensuring that the measurement results under different process conditions are all under standard conditions.

[0093] Commonly used traffic data collection and compensation formulas:

[0094]

[0095] Please refer to Figure 1 The above formula is programmed as follows in the energy center:

[0096] If DPin <MIN Then

[0097] FlowTP=0

[0098] Elseif DPScale>0Then

[0099] If Mode = 1, then

[0100] Fx = DPin / DPScale

[0101] Elseif Mode = 2Then

[0102] Fx=(DPin / DPScale)*(Pr+0.137411) / (Pd+0.137411)

[0103] Elseif Mode = 3Then

[0104] Fx=(DPin / DPScale)*(0.4619*(Td+273.15) / (Pd+0.101325)-9.7+0.0132*Td) / (0.4619*(Tr+273.15) / (Pr+0.101325)-9.7+0.0132*Tr)

[0105] Elseif Mode = 4Then

[0106] Fx=(DPin / DPScale)*(273.15+Td) / (0.101325+Pd)*(0.101325+Pr) / (273.15+Tr)

[0107] Endif

[0108] If Sqrt = 0, then

[0109] FlowTP = FMax * Fx

[0110] Else

[0111] FlowTP = FMax * Sqrt(Fx)

[0112] Endif.

[0113] Code meaning and explanation:

[0114]

[0115]

[0116] The above programming instructions are as follows:

[0117] When temperature and pressure compensation is not performed:

[0118] The Mode formula is set to 1, and the Sqrt root is also set to 1.

[0119] When performing temperature and pressure compensation:

[0120] The Mode formula is set to 4, and the Sqrt square root is set to 1. Meanwhile, Pd and Td are set to the design pressure and design temperature according to the flow calculation report. Pr and Tr are connected to the actual measured pipeline medium pressure and temperature for temperature and pressure compensation.

[0121] When performing stress compensation:

[0122] The Mode formula is set to 4, the Sqrt square root is set to 1, and Pd is set to the design pressure according to the flow calculation report. Pr is connected to the actual measured pipeline medium pressure, and Td and Tr are set to the same value of 1 for pressure compensation.

[0123] When performing temperature compensation:

[0124] The Mode formula is set to 4, the Sqrt square root is set to 1, and Td is set to the design temperature according to the flow calculation report. Tr is connected to the actual measured pipe medium temperature, and Pd and Pr are set to the same value of 1 for temperature compensation.

[0125] When performing fixed-value compensation:

[0126] The Mode formula is set to 4, and the Sqrt square root is set to 1. Meanwhile, Pd and Td are set to the design pressure and design temperature according to the flow calculation report. Pr and Tr are set to fixed pressure and temperature values ​​based on actual conditions, and fixed-value temperature and pressure compensation is performed.

[0127] 2. The formula for measuring Viagra is: Please refer to Figure 2 The energy center is programmed as follows:

[0128] If hw <= MIN, then

[0129] Qv=0

[0130] Else

[0131] Qm = hw * (Pf + 100) / (Tf + 273.15)

[0132] Qm1=Qm / Zf

[0133] Qm2 = sqrt(Qm1)

[0134] Qv=Ci*Qm2

[0135] Endif.

[0136] Code meaning and explanation:

[0137]

[0138] The compensation for the Viagra formula is as follows:

[0139]

[0140] Please refer to Figure 3 The energy center is programmed as follows:

[0141] If FMax <= MIN, then

[0142] FlowTP=0

[0143] Else Fx=(273.15+Td) / (101.325+Pd)*(101.325+Pr) / (273.15+Tr)FlowTP=FMax*Sqrt(Fx)

[0144] Endif.

[0145] Code meaning and explanation:

[0146]

[0147] The above programming instructions are as follows:

[0148] When performing temperature and pressure compensation

[0149] FMax connects to the actual measured flow rate. Pd and Td are set to the design pressure and design temperature according to the flow calculation report, respectively. Pr and Tr connect to the actual measured pipeline medium pressure and medium temperature for temperature and pressure compensation.

[0150] When performing stress compensation

[0151] Pd is set according to the design pressure in the flow calculation report. Pr is connected to the actual measured pressure of the pipeline medium, and Td and Tr are set to the same value of 1 for pressure compensation.

[0152] When performing temperature compensation

[0153] Td is set according to the design temperature in the flow calculation report. Tr is connected to the actual measured temperature of the medium in the pipeline. Pd and Pr are set to the same value of 1 for temperature compensation.

[0154] When performing fixed-value compensation

[0155] Pd and Td are set with design pressure and design temperature according to the flow calculation report. Pr and Tr are set with fixed pressure and temperature according to the actual situation, and fixed temperature and pressure compensation is performed.

[0156] 3. The Energy Center has added measurement overflow and small signal correction.

[0157] The Energy Center processed the values ​​of signals that exceeded the measurement range, and also processed the values ​​of zero data due to network or acquisition problems. This overcame the problem of calculating large data when the denominator is zero, and a unified approach was taken to cut off small signals, with a cut-off amount of 1%.

[0158] Removal function formula:

[0159] Please refer to Figure 4 The above function is programmed as follows:

[0160] If Pin <= min Then

[0161] Pout=0

[0162] Elseif Pin>max Then

[0163] Pout = max

[0164] Endif.

[0165] Code meaning and explanation:

[0166]

[0167] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the measurement accuracy of gas pipeline networks, characterized in that, include: Step 1: Improve the measurement accuracy of instruments. Specifically, the measurement accuracy of primary measuring equipment in the gas pipeline network shall not be lower than Class 1, and the measurement accuracy of secondary measuring equipment in the gas pipeline network shall not be lower than Class 0.

2. Step 2: Perform temperature and pressure compensation for flow measurement. When measuring flow, convert the measured flow value into the corresponding standard condition flow value based on the actual temperature and pressure at the time of measurement. The primary measuring device is the device directly used for flow measurement, and the secondary measuring device is other auxiliary equipment used in conjunction with the primary measuring device. The secondary measuring device includes a differential pressure transmitter and a distributor. In step two, when the calculation formula used for flow measurement is a general formula, the following formula is adopted: Perform compensation calculations; Where FlowTP is the actual flow rate, Fmax is the measured maximum flow rate, DPin is the instantaneous flow rate input, DPScale is the differential pressure signal range, Td is the design temperature, Pd is the design pressure, Pr is the operating process pressure, and Tr is the operating process temperature. It also includes step three, adding measurement overflow and small signal correction; Measurement overflow correction is as follows: when the measured value of a primary measuring device exceeds the upper limit of the measuring range of that primary measuring device, the portion exceeding the range is deducted. Small signal adjustment is as follows: when the measured value of the primary measuring device is not greater than the lower limit of the range of the primary measuring device, the measured value is reduced and the signal is cut off. In step one, the measured components are analyzed, the mixture is recalculated based on the composition of the mixed gas, the instrument system is adjusted according to the new parameters, and the system is calibrated to ensure that the instrument is within the system error range. In step two, temperature measuring points are added to the pipeline and set to automatic compensation. For pipelines without measuring points, fixed compensation is applied. When the weather temperature changes significantly, measurements will be taken again and the fixed compensation value will be modified. In step three, during measurement, sometimes the instrument measurement exceeds 100%. After inspection, it is found that the problem is not with the range, but with external interference or other reasons. Therefore, the portion of the range exceeding 100% is deducted. Sometimes, due to the current of differential pressure transmitters, there may be zero drift, temperature drift, etc., and small signals may be generated. These small signals are cut off and controlled within 2%.

2. The method for improving the measurement accuracy of gas pipeline networks according to claim 1, characterized in that, In step two, when the calculation formula used for flow measurement is the specific formula for Viagra flow measurement, the specific formula for Viagra flow measurement is: ; Where Qv is the flow output, Ci is the flow coefficient, hw is the differential pressure input, Zf is the temperature coefficient, Pf is the input gauge pressure, and Tf is the input temperature.

3. The method for improving the measurement accuracy of gas pipeline networks according to claim 2, characterized in that, When using the specific formula for V-bar flow metering, temperature and pressure compensation is applied. The formula is calculated as follows: ； Where FlowTP is the actual flow rate, Fmax is the measured maximum flow rate, Pr is the operating process pressure, Tr is the operating process temperature, Pd is the design pressure, and Td is the design temperature.

4. The method for improving the measurement accuracy of gas pipeline networks according to claim 1, characterized in that, For the trimming of small signals, the amount of removal should not exceed 2% of the total signal.

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