There are three kinds of optimization algorithms in the measurement of natural gas. The calculation amount of the reduction coefficient of the optimization algorithm is very large. It is mainly used for the recovery of flow meter and the comprehensive application of on-line body composition detector. The calculation amount of serg8 optimization algorithm is small, in addition, the basic measurement precision provisions are also considered. Key in the main parameters of sgerg88 optimization algorithm: C02 mole fraction, H2 mole fraction, high calorific value (m) / m3) and density. In addition, it is also necessary to input the standard temperature (° C) of compensation for pure natural temperature and pressure. For the same sample of compensation for body temperature and pressure, the compensation method for the coefficient of expansion includes two methods: full-automatic calculation of the coefficient of expansion and fixed fixed coefficient of expansion. If the method of full-automatic calculation of the coefficient of expansion is selected, the value of the coefficient of expansion will be calculated automatically in the whole process of measuring the total flow If you choose to type in the fixed constant expansion coefficient method, you must type in the setting to expand the coefficient. The main parameters of physical properties under the standard of reference materials, including relative density (PS), upper volume calorific value (HS) and

2.5 the upper volume calorific value (H ~ s) of water and steam shall be calculated in the way required by GB / 11062. The main parameters of physical properties under the actual operation standard to be applied for calculation of gas steam flowmeter include: relative density p, reduction coefficient b, viscosity μ, isentropic index value K, which shall be calculated in the way required by GB / t214462008.

The key to the optimization algorithm of water and steam is to calculate according to the iapwsifc1997 formula of the International Association of water and steam thermal characteristics. The real-time physical property variables of water and steam can be calculated only by inputting the temperature and flowmeter pressure. The substances of water and steam usually involve the calorific value measurement. The instantaneous calorific value caused by substances can be obtained by multiplying the enthalpy value by the instantaneous total flow value. In fact, the calorific value measurement function can be turned off or turned on according to the calorific effect.

3.1 serial port setting 3 basic parameters

The communication mode includes RS485 and RS232. At present, the system bus of instruments is widely used, and the detailed address of 485 slave of machine equipment is set according to the communication tag number. The default setting of communication protocol is MODBUS-RTU, because RTU is more efficient than ASCII. The main parameters of baud rate, check bit and termination bit are 9600-8-n-1. For the application of low-speed optocoupler isolation, the baud rate should be adjusted to 2400 or lower to ensure the credibility of transmission.

The differential pressure method includes flowmeter pulse; the differential pressure data signal includes 4 ~ 50mA (default setting) and 1 ~ 5V analog output. Differential pressure enterprises have 3.2 differential pressure collection Pa.KPa (default setting) and MPa. The limit of differential pressure data signal and the low limit of differential pressure data signal are respectively set with the differential pressure limit value matching 50mA and 2mA. When the standard value of differential pressure transmission regulator is out of the measurement range, the common fault alternative value of differential pressure shall be selected for calculation and alarm output.