The method of calibration of hygrometers dew point of natural gas and device for its implementation

 

The invention relates to gas industry. The method includes the saturation flux source of dry inert gas with water vapor, the flow wet gas diluted in hygrometer and construction of calibration characteristics. Dilution wet gas source of dry inert gas is carried out, at least until the doubled value of the desired concentration. Saturate a source of dry inert gas alcohol vapor or heavy hydrocarbons, dilute the mixture a source of dry inert gas, at least until the doubled value of the desired concentration and direct it into the flow of wet dilute gas in a quantity equal to the number of additional flow source of dry inert gas blocking the latter. The method is carried out with the help of the device containing the hygrometer and interconnected, the saturator water and the camera dilution, United with rotameters and chokes with a source of dry inert gas. Moreover, the device is equipped with additional saturator and Luggage dilution, United among themselves and with rotameters and chokes with a source of dry inert gas, and equipped with a host of mixing dilute flows, which on the. the crystals, 2 Il.

The invention relates to gas industry and can be used in particular for the calibration of hygrometers used to measure the dew point of natural gas containing vapors of alcohol or heavy hydrocarbons.

The problem of determining the humidity of the gas in the gas industry largely associated with the use of methanol, deg and other substances to fight hydrate formation in wells, pipelines and process plants. Getting into the sensor humidity meter (hygrometer), these alcohols and heavy hydrocarbons contained in the gas, leading to an overestimation of the actual values of the dew point moisture and, consequently, underestimate the quality of the delivered natural gas, which is important in the settlement of gas. The difference between the measured hygrometer and the actual value of the dew point moisture the greater, the higher the concentration of alcohol vapor and heavy hydrocarbons in the gas and the drier the gas. The problem is complicated by the fact that one and the same, measured by the hygrometer, the value of the dew point (at P=const) can meet the varying moisture content in different concentrations of alcohol vapor and heavy hydrocarbons in the gas.

In connection with the national network of gas pipelines, the necessity of taking into account the influence of vapors of alcohols and heavy hydrocarbons on the measurement of humidity - dew point of natural gas is becoming increasingly important.

There is a method of calibration of hygrometers dew point of natural gas, including a saturation flux source of dry inert gas with water vapor, the number of subsequent cycles of dilution, the diluted feed wet gas in hygrometer and construction of calibration characteristics of the hygrometer for a range of concentrations of water vapor in natural gas (the Caliph A. L. and other Instruments for determining the moisture content of natural gas. M, IDC Gazprom, 1995, pp. 38-39).

A device for calibration of hygrometers dew point of natural gas containing hygrometer and interconnected, the saturator water and the camera dilution, United with rotameters and chokes with a source of dry inert gas (Caliph A. L. and other Instruments for determining the moisture content of natural gas. M, IDC Gazprom, 1995, pp. 38-39).

The disadvantage of this method of calibration of hygrometers dew point of natural gas that calibrated by this method hygrometer gives higher values of dew point moisture, because the method does not provide the ability to create prirodnogo gas, which leads, respectively, to an underestimation of the quality of natural gas.

A disadvantage of the known device for the calibration of hygrometers dew point of natural gas is that the hygrometer gives distorted values dew point moisture.

The present invention is to improve the accuracy of determining the dew point of natural gas and moisture.

The problem is solved due to the fact that in the proposed method of calibration of hygrometers dew point of natural gas, including a saturation flux source of dry inert gas with water vapor, the number of subsequent cycles of dilution, the diluted feed wet gas in hygrometer and construction of calibration characteristics of the hygrometer for a range of concentrations of water vapor in natural gas, the dilution of the humid gas source of dry inert gas is carried out, at least until the doubled value of the desired concentration, while diluted wet gas is mixed in equal parts with additional flow source of dry inert gas and serves mixture in hygrometer, then saturate a source of dry inert gas alcohol vapor or heavy hydrocarbons, dilute the mixture a source of dry inert gas, p is gas in the quantity is the number of additional flow source of dry inert gas, overlapping the latter, then repeat these steps with regard to concentrations corresponding to the content of water vapor and alcohol vapor or heavy hydrocarbons in natural gas.

The proposed method is implemented using the device for the calibration of hygrometers dew point of natural gas containing hygrometer and interconnected, the saturator water and the camera dilution, United with rotameters and chokes with a source of dry inert gas, with further saturator and Luggage dilution connected with each other and with rotameters and chokes with a source of dry inert gas, and equipped with a host of mixing the diluted streams, comprising at least three identical rotameter, the two inputs of which are connected with their corresponding chokes reset and cameras dilution, the entrance to the third - through reactor with a source of dry inert gas, and the outputs of all three are connected via shut-off valves between and through the mixing chamber and the pneumatic resistance with hygrometer.

Moreover, to generate the multi-component vapor-gas mixtures is of. In this case, the dilution gas flow, saturated, for example, pairs of alcohols or hydrocarbons, are concentrations of n times greater than required, where n is the number specified impurity components in the mixture, and the flows of dilute gases before entering the hygrometer is mixed in equal parts.

In Fig. 1 shows a schematic diagram of a device for the calibration of hygrometers natural gas.

In Fig.2 depicts the calibration characteristics of the hygrometer.

Device for the calibration of hygrometers dew point of natural gas contains a source of dry inert gas 1, saturator 2 water saturator 3 for alcohol (or heavy hydrocarbons) and node mixture diluted with 4 threads. The saturator 2 for water supplied by the flowmeter 5 flow wet gas (gas saturated with water vapor), a rotameter 6 flow source of dry inert gas, the two inductors 7 and 8 fine adjustment to control the flow of wet and source of dry inert gas, and the chamber 9 dilution. Similarly, the saturator 3 for alcohol (or hydrocarbon) is supplied by the flowmeter 10 gas flow saturated with vapors of the liquid filled in the saturator, the rotameter 11 flow source of dry inert gas, two grossularia dilution 14. Site mixing diluted threads 4 includes three identical rotameter 15, 16, and 17. The inputs 18 and 19 of the flowmeter 15 and 16 are connected respectively with the throttles 20 and 21 reset and camera dilution 9 and 14 with a fountain offering 2 and 3. The entrance 22 of the rotameter 17 is connected through a throttle 23 with a source of dry inert gas. The outputs 24, 25 and 26 rotameters 15, 16 and 17 through the valves 27, 28 and 29 are connected together and through a mixing chamber 30 and the pneumatic resistance 31 with calibrated the hygrometer 32. For trapping fluid at the outlet of the fountain offering 2 and 3 installed filters 33 and 34, and to trap moisture contained in the liquid filled in the saturator 3, trap 35. The temperature of the liquid in the fountain offering thermometers measure 36 and 37, the pressure set by the regulator 38. The valves 39 and 40 are designed to prevent the release of liquid from the fountain offering 2 and 3 at the time of stopping the operation of the device. To prevent suction of atmospheric air into the system (by counter-current), output chokes 20 and 21 installed tube extension 41 and 42.

The proposed method is as follows. The source of dry inert gas is sent from the source 1 through the saturator 2, in which pre-soaked in distilled is the ETP of the regulator and then open the shut-off valve 39. The saturated vapor pressure and consequently the concentration of water vapor above the liquid in the saturator depend on the temperature of the saturator (thermometer 36) and the nature of matter in the saturator (water).

Wet gas (gas saturated with water vapor at a temperature of saturator), leaving the saturator 2, dilute source of dry inert gas in the chamber dilution 9 and then through a throttle reset 20 site mixing threads 4 are taken out to the atmosphere. The concentration of water vapor in the diluted wet gas depends on the pressure of saturated water vapor in the saturator 2, and the ratio of expenses wet and dry gas. The flow rate of the wet gas set using the throttle 7 and rotameter 5, flow rate source of dry inert gas through the reactor 8 and rotameter 6. The dilution is carried out before the doubled value of the desired concentration of water vapor in the gas. Then open the valve 27 and smoothly covering the throttle reset 20, channel a portion of the diluted wet gas from the chamber 9 through dilution flowmeter 15, the mixing chamber 30 and the pneumatic resistance 31 in calibrated hygrometer 32. The flow rate of the diluted wet gas through the rotameter 15 should be 1/n the speed required for gradeitem the 20 output into the atmosphere. Before entering the hygrometer diluted stream of wet gas is mixed in equal parts with additional flow source of dry inert gas. To do this, open the valve 29, directing a source of dry inert gas from source 1 into the mixing chamber 30. The additional speed of flow of the source of dry inert gas install orifice 23 to the flowmeter 17. Next direct source of dry inert gas from source 1 through the saturator 3, in which a pre-filled, for example, alcohol. To do this, open the shutoff valve 40. Gas, saturated with alcohol vapor, leaving the saturator 3, dilute source of dry inert gas in the chamber dilution 14 and then through the orifice 21 are taken out to the atmosphere. The alcohol vapor concentration in the diluted gas at the outlet of the chamber 14 dilution depends on the saturated vapor pressure of the alcohol in the saturator 3 and the ratio of expenditure flows, saturated alcohol vapor and a source of dry inert gas, which are mounted respectively inductors 12 and 13 on flowmeters 10 and 11. The dilution is carried out before the doubled value of the desired concentration of alcohol vapor in the gas. Then open the valve 28 and smoothly covering the throttle reset 21 direct part rosbusinnesconsulting flow source of dry inert gas through the rotameter 17, this additional flow is the source of dry inert gas block valve 29. Mixing the diluted flow wet gas and gas containing vapors of alcohol is carried out in the mixing chamber 30. From the mixing chamber 30, the gas with the specified concentrations of water vapor and alcohol comes through the pneumatic resistance 31 in calibrated hygrometer 32.

Thus, when replacing an additional stream source of dry inert gas a gas stream containing vapors of alcohol, the concentration of water vapor in the total flow of gas into the hygrometer does not change.

Next, repeat these steps with the other concentrations corresponding to the content of water vapor and alcohol (or hydrocarbons) in natural gas. According to the experimental data to build the calibration characteristics of the hygrometer.

An example of the method.

The method of calibration of hygrometers dew point of natural gas used for experimental evaluation of the influence of the vapor of ethyl alcohol readings hygrometer adsorption type.

In the saturator 2 flooded with distilled water in the saturator 3 - 92% aqueous solution of ethanol (by volume). The trap 35 is filled with calcium chloride. The temperature of the fountain offering 2 and 3 ranged from 16.5 avleat a pressure of 1 kgf/cm2. Next, open the shutoff valve 39 and through inductor 7 and rotameter 5 gas is directed through the saturator 2 in the camera dilution 9, and out through full throttle reset 20 gas output into the atmosphere. In this chamber 9 through the inductor 8 and rotameter 6 direct source of dry inert gas from source 1. For submission to the hygrometer 33 of the gas stream, the dew point temperature of the moisture which is equal to - 49oWith the concentration of water vapor 0,0042% vol.), set the speed of the wet gas through the rotameter 5 of 20 cm3rpm (throttle 7) and the flow velocity of the source of dry inert gas through the rotameter 6 equal to 4500 cm3rpm (throttle 8). Then open the valve 27 and through a throttle reset 20 and rotameter 15 directs the flow of the diluted wet gas through the mixing chamber 30 and the pneumatic resistance 31 in calibrated hygrometer 32. The velocity of the gas through the rotameter 15 set equal to 250 cm3/min, the excess gas is discharged through the orifice 20 into the atmosphere. Next, open the shutoff valve 29 site mixing dilute streams 4 and using the throttle 23 set the speed of the additional flow source of dry inert gas through the rotameter 17 is equal to the flow rate of the diluted wet gas through rotameo inert gas, at the entrance to the hygrometer provide the necessary gas flow rate (500 cm3/min) and the desired concentration of water vapor in the gas (dew point temperature - 49oC). Removing indications hygrometer, get the first point to build its calibration characteristics (dew-point temperature is 49oWith, the alcohol is not available).

Then open the shutoff valve 40 and through inductor 12 and flowmeter 10 direct the gas from the source 1 through the saturator 2 in the camera dilution 14, and out through full throttle reset 21 take in the atmosphere. Through this chamber 14 through inductor 13 and rotameter 11 direct source of dry inert gas from source 1. For submission to the hygrometer 33 gas stream containing 0,11% vapors of ethyl alcohol, set the speed of the gas stream saturated with alcohol vapor through the flowmeter 10, equal to 200 cm3/rpm (throttle 12) and the flow velocity of the source of dry inert gas through the rotameter 11 equal to 4500 cm3rpm (throttle 13). Then open the valve 28 and the orifice 21 set the flow rate of the diluted gas containing vapors of alcohol, through the flowmeter 16 is equal to 250 cm3/min, with an additional current source of dry inert gas perekryvala inert gas, comes identical to the gas stream containing vapors of alcohol, having first achieved the concentration of water vapor in the total gas flow does not change. From the mixing chamber 30, the gas with the desired alcohol vapor concentration and the desired concentration of water vapor (with the required dew point for water is continuously supplied through the pneumatic resistance 31 in calibrated hygrometer 32. Removing indications hygrometer, get the second point to build its calibration characteristics (temperature dew point moisture - 49oWith the alcohol vapor concentration of 0.11% vol.). Then overlap the shutoff valve 28 and opening the shutoff valve 29. Next, repeat these steps with the other concentrations.

In this example, performed four series of dimensions, each of which was characterized by its own dew point of the moisture - 49oC; - 40oC; -29oWith; - 21,5oC).

The vapor concentration of alcohol in each series of measurements was changed discretely from 0.03% about. to 1.3%. Each series consisted of 19 measurements of dew point, each measurement answered a certain concentration of alcohol vapor.

Reportedly built calibration characteristics of the hygrometer (Fig.2).

As can be seen from the graph in Fig.2 pairs uh is this specified range, which leads to an underestimation of the real qualitative indicators of gas. The same is measured by the hygrometer is the dew point corresponding to the different moisture content at p=const and different content of the vapors of alcohol. So, hygrometer shows the dew point temperature - 30oWith its actual value (moisture) - 49oAnd the vapor concentration of ethanol is 1.3%. ; if the actual value 43oAnd concentration of 0.9% vol.; when the actual value is 38oC and a concentration of 0.8% vol.; when the actual value of the 36oC and a concentration of 0.7% vol.; and only when the concentration of the vapors of ethyl alcohol below 0.1%. measured by the hygrometer dew point temperature (- 30oSince in our example) corresponds to the actual temperature dew point humidity.

Presented on Fig. 2 calibration characteristics of the hygrometer enable the measured values of the dew point temperature and a known alcohol vapor concentration in the gas (e.g., chromatographic analysis) to find the actual value of the temperature dew point humidity.

The application of the inventive method the calibration of hygrometers dew point of natural gas and device for its implementation allows: - to assess the impact of vapors of alcohols and hygrometer limit value of the content of alcohols, from which readings hygrometer overrated and definitely not related to the content of water vapor in natural gas; - to calibrate hygrometers dew point of natural gas taking into account the impact on their readings of methanol vapor and a known concentration of the latter, the measured values of the dew point to determine its actual value (temperature dew point humidity); - to increase the accuracy of determining the dew point of natural gas and moisture, which is very important for the gas industry, because the humidity of the gas is one of the most important quality parameters that determine the value of exported natural gas.

Claims

1. The method of calibration of hygrometers dew point of natural gas, including a saturation flux source of dry inert gas with water vapor, the number of subsequent cycles of dilution, the diluted feed wet gas in hygrometer and construction of calibration characteristics of the hygrometer for a range of concentrations of water vapor in natural gas, characterized in that the dilution of the humid gas source of dry inert gas is carried out, at least until the doubled value of the desired concentration, while diluted wet Gaer, then saturate a source of dry inert gas alcohol vapor or heavy hydrocarbons, dilute the mixture a source of dry inert gas, at least until the doubled value of the desired concentration and direct it into the flow of wet dilute gas in a quantity equal to the number of additional flow source of dry inert gas, overlapping the latter, then repeat these steps with regard to concentrations corresponding to the content of water vapor and alcohol vapor or heavy hydrocarbons in natural gas.

2. Device for the calibration of hygrometers dew point of natural gas containing hygrometer and interconnected saturator water and the camera dilution, United with rotameters and chokes with a source of dry inert gas, characterized in that it is provided with an additional saturator and Luggage dilution, United among themselves and with rotameters and chokes with a source of dry inert gas, and equipped with a host of mixing the diluted streams, comprising at least three identical rotameter, the two inputs of which are connected with their corresponding chokes reset and cameras dilution, the input of the third valve between a and through the mixing chamber and the pneumatic resistance with a hygrometer.

 

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