0 Foreword In the metallurgical industry, gas as an important secondary energy source, its instantaneous flow and accurate measurement of cumulative flow, not only affects the control effect of the relevant control system, but also is an important basis for the internal market operation of the company and cost accounting. Henan Yuguang Zinc Industry Co., Ltd. Power Plant is responsible for the management and maintenance of the entire company's gas pipeline network. Based on the analysis of the components and working conditions of the gas, the survey summarized the experience of using other gas flow metering devices, installed six sets of online-installed integrated Annubar flowmeters, and built the gas as its core. Flow detection system. After one year of operation, the entire company's gas pipeline network has been successfully monitored and measured. 1 Proposed issue In the production of metallurgical enterprises, whether it is blast furnace gas or converter gas, water, dust and other impurities are relatively high, easy to produce condensed sediments. In addition, the gas pipe diameter is large, the operating pressure is small, the flow rate of the gas in the pipe is small, and the flow measurement is difficult. Although orifice plate flowmeters are easy to install and install, they have small range ratios, low precision, and large pressure losses, and they cannot meet the precise measurement of gas. The previously used diamond bars have poor anti-blocking properties and have a low differential pressure. They need to be shut down for maintenance during maintenance and affect normal production operations. Therefore, they cannot meet the requirements. 2 On-line installation of integrated Annubar flowmeter features The flowmeter is a product of Rosemount Inc. of the United States. It uses the differential pressure principle to detect the flow, which solves all problems of orifice flowmeters in large-diameter flow measurement. It has the following features. 2.1 T-barrier design The cross section of the flowmeter throttle has a unique T-shaped blocking design structure shown in Figure 1. During operation, the fluid medium generates a high pressure area on the flat front side of the throttle. The particulate impurities in the fluid are deflected around the high pressure area and flow away from the stagnation area of ​​the flat back pressure inlet. The particulate impurities are difficult to clog the pressure hole. This reduces the chance of blockage in high and low pressure areas. The adsorption accuracy of some impurities does not cause catastrophic measurement errors on other conventional equalizer flowmeters. Data shows that when the non-viscous dry impurity content in the fluid is not more than 6500 mg/m3, it has almost no effect on the T-type Annubar flowmeter. Fig. 1 T-type anti-blocking design (white is high pressure area, blue is low pressure area) 2.2 slot pressure hole The velocity distribution of the fluid in the pipeline is not uniform across the cross-section of the pipeline. Accurate velocity flow meters require the correct average flow rate of the fluid. The high-pressure side pressure-receiving hole on the front of the flow meter throttling element is a groove type design. The length of the notch spans the cross section of the entire gas pipeline, and the velocity sampling of the fluid reaches more than 85%, and 12 times more than the throttle valve of various shapes. The above sampling rate of the flow rate results in a more accurate measurement of the average flow rate and a larger flow differential pressure value. Figure 2 Relative Differential Pressure Signal Strength (abscissa) 2.3 Online plug-in installation and maintenance During installation, a specially designed mounting base and isolation valve are installed above the pipeline, and then an isolation annual flowmeter is installed in the pipeline through the isolation valve. Due to the presence of the isolation valve, installation and maintenance can be performed without stopping the operation of the gas. Because the front high-pressure pressure notch of the T-type Annubar flowmeter spans the entire pipeline, the average measurement accuracy of the fluid is increased, and the installation requirements of the T-type Annubar flowmeter are also greatly reduced. It is allowed to have a deviation of ±5o in the X, Y, Z triaxial directions. The deviation of ±5o is clearly judged by human eyes, and the installation personnel can more easily install and debug. 2.4 Real-time Dynamic Temperature Pressure Compensation The integrated Annubar flowmeter incorporates a 0.065% accurate differential pressure transmitter, a 0.065% accurate pressure transmitter, a temperature transmitter, a high-speed CPU, and a large-capacity data memory. The built-in large-capacity data storage stores the physical data used in the calculation formulas for various fluids under different pressures and temperatures, including density, viscosity, gas constant, compression coefficient, equal volumetric heat, etc. The working pressure and temperature are calculated by taking the corresponding data from the database and putting it into the compensation formula. This flow calculation formula also compensates for various effects of the center hole of the pipe under different temperatures and pressures, such as thermal expansion and contraction, to eliminate the factors that cause flow measurement errors to the greatest extent. 3 Issues to be aware of when using Annubar flowmeters (1) The mechanical dimensions of the Annubar flowmeter must be tailored to the size of the pipe to be installed. The user-supplied parameters must include parameters such as pipe outside diameter, wall thickness, common flow, etc., in the manufacturing process of Annubar. The calibration of the mid-flow measurement range is based entirely on user-supplied data calculations. Therefore, if flow data and pipe size are provided based on experience and impression, it will cause a large measurement error. (2) The differential pressure signal generated by the differential pressure flowmeter is generally relatively small, the minimum is only 20 ~ 30Pa, and the size of the differential pressure signal generated by the constant flow tube flowmeter is closely related to the Reynolds number of the fluid condition. For differential pressure measurement less than 1kPa, especially differential pressure less than 0.5kPa, it is very test the performance of the transmitter. Various constant velocity flowmeters have a very large fluctuation in K at such a low flow rate, affecting the measurement accuracy. (3) After the differential pressure signal is collected, try not to use pressure-inducing pipes to increase the signal-to-noise ratio of differential pressure signal transmission and reduce leakage. We have adopted an integrated direct installation of Annubar, three-valve manifolds, and differential pressure transmitters to completely eliminate pressure piping, drain valves, and mounting brackets. In this way, not only the leakage caused by the use of pressure-inducing piping, and the problem of differential pressure signal distortion are reduced, but also the cost is reduced and the accuracy is improved. 4 Use effect The on-line integrated Annubar flowmeter was installed and put into operation in Henan Yuguang Zinc Industry Co., Ltd. for more than one year. Through production practices, comparative experiments and data statistics, it proved that the effect of the pipeline gas measurement in the plant was significant. 4.1 Low flow rate flow is measured Gas pipeline diameters up to “gas power generation†are 1500mm, the maximum flow rate is 70,000Nm3/h, and the common flow rate is 45000Nm3/h. A Bar-type flowmeter cannot be used to measure the flow rate at all. With the integrated Annubar flowmeter, the instantaneous flow can be measured to a minimum of 18000Nm3/h in practical applications. 4.2 Reduce the chance of clogging Since the beginning of its use, only the Annubar flowmeter installed at the exit of No. 6 Blast Furnace has caused a blockage in the flowmeter due to unexpected reasons, and the flow measurement value has been reduced from normal 100000Nm3/h to 75000Nm3/h. It has worked so far. 4.3 Online installation and maintenance do not affect production Using other flowmeters requires stopping the operation of pipeline gas and affecting normal production. The on-line installation type integrated Annubar flowmeter completely solves this problem. When installing and maintaining the on-line installation type integrated Annubar flowmeter, the isolation valve can be cut off to ensure that the gas will not leak and achieve safe continuous production. 5 Concluding remarks In summary, when selecting a flow measurement device, not only theoretical knowledge, but also actual process conditions and media characteristics must be analyzed, and a detection device suitable for the operating conditions should be selected. The integrated Annubar flowmeter has been installed and operated for more than one year. The accuracy of gas measurement and metering has been greatly improved, and good economic benefits have been achieved, demonstrating its reliability in gas measurements with high impurity content. The gas metering system has produced good results for the gas energy calculation and production scheduling of the entire Jiyuan Iron and Steel Group. Jiangsu Manrui New Materials Co., Ltd , https://www.manruiwire.com
