Experimental device
The experimental devices employed in this study were condensed weighted weight-bearing steam flow metering standards, negative pressure sounding nozzle gas flow metering standards, quality method water flow metering standards. Among them, the condensed weighing heavy-action steam flow metering standard device is domestic * with steam real current calibration flow standard device, the expansion uncertainty is 0.1% (k = 2), the detection flow range is 0.01 ~ 10, T / H, its work The principle is shown in FIG. 2, with superheated steam as the verification medium, the principle of condensation weighing through the steam flow meter is performed, and the steam flow meter is laminated. The gas device is a negative pressure sounding nozzle gas flow metering standard device, the expansion uncertainty is 0.25% (k = 2), and the detection flow range is 2.5 to 10,000, m3 / h. The water supply is a quality method of water flow metering standard device, and the expansion uncertainty is 0.05% (k = 2), and the detection flow range is from 0.05 to 200, m3 / h.
2. Experimental program
The steam flow meter of different manufacturers, models, calibers, according to the steam flowmeter national verification procedure [12], separately on the steam device, air device, and water devices, where the steam device is 150, and the temperature is around , The pressure is tested under the conditions of 0.35 and MPa, and the verification flow sequentially from ZUI traffic to ZUI mass flow 20%, 40%, 60%, 100%, total of 6 flow points, and repeat each traffic point. 3 times. At present, the test experiment of nearly 100 steam flow meters is carried out, and the unqualified steam flow meter has been carried out. Summarize these steam flowmeter experiments, the direction of the instrument coefficient is basically similar, and the size of the deviation has a difference, within a certain range . This article is only analyzed by representative DN50 and DN100 2 steam flow meter experimental data, compared to different flow point instrument coefficients.
3. Experimental data
Through 3 sets of experimental tests under different fluid media, the instrument coefficients under the 3 sets, the instrument coefficient deviation, and the amount of instrument coefficients E ', E'A, E'A, E'E, E'A, E'A, E'A, E'E, by analysis. The curve relationship of the instrument coefficient and flow is shown in Figures 3 and 4.
As can be seen from experimental data, the steam flowmeter is reduced in air, water, and steam fluid conditions, and the amount of air and vapor fluid dielectric increases with flow rate, which is consistent with the theoretical calculation analysis. By accumulating experimental data, the air is 0.2% to 1.0%, which is 0.2% to 1.0%, which measured by the fluid medium, the fluid medium measured by the fluid medium, the size of the K value deviation of the instrument factor. The manufacturer and specification model varies, but the positive and negative trends of the deviation is basically the same.
(1) When the high temperature steam is measured, it is necessary to consider the effects caused by the linear expansion caused by the temperature, otherwise the instrument factor is large. The measurement error can be derived according to the article in the article.
(2) The effect of the gas compressibility on the factor of the steam flowmeter, the influence of the relevant parameters of the medium flow rate U, the pressure P, density ρ, and the like, and the flow rate U is proportional to the flow rate u, and the 11P / ρ is changed into Inverse, the entropy index κ of gas does not cause unilateral direction of the instrument coefficient.
(3) The compressibility of different media will affect the steam flowmeter instrument coefficient. The instrument coefficient in the air medium is large, the water is small, the steam zui is small, and the effect of steam medium on the instrument coefficient in the same flow rate is less than air. The influence, the specific difference is calculated by analyzing the conditions under conditions of conditions.
(4) According to the experimental data, the steam flow meter instrument coefficient measured in different media is consistent with the theoretical calculation analysis, but 2 results have certain deviations, which may be due to other physical parameters of the medium to the instrument factor, It also needs to be in-depth theoretical analysis, try to use the real-flow calibration to obtain the instrument factor in actual use.
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