A differential pressure flow measurement device and method based on the principle of swirling flow

Abstract

A differential pressure flow measurement device and method based on the principle of swirling flow, comprising a pipe with a diameter of D, a cyclone that closely fits the pipe wall and is statically arranged inside the pipe, and the pipe downstream of the cyclone is provided with The pipe wall pressure taking pipe and the pipe center pressure taking pipe, the outlets of the pipe wall pressure taking pipe and the pipe center pressure taking pipe are respectively connected with the two fluid inlets of the differential pressure transmitter; The average flow velocity is obtained, and then the flow rate is obtained according to the average flow velocity. Compared with the traditional differential pressure flowmeter, the required straight pipe section is greatly shortened, and the pressure difference is also greatly reduced, and it has an excellent effect on the situation of rotating flow and eddy current. Adaptability; for multiphase fluids, the cyclone device can rectify complex multiphase fluids into a "phase-separated" state in the tube that is symmetrical about the axis, making it easier to measure.

Description

technical field [0001] The invention belongs to the technical field of fluid measurement, and in particular relates to a differential pressure flow measurement device and method based on the principle of swirling flow. Background technique [0002] In the field of flow measurement, differential pressure flowmeters account for more than 1 / 3 of the total number of flowmeters. No matter from the perspective of development history, application scope and number of uses, it is well-deserved as the largest category of flowmeters. At present, the commonly used differential pressure flowmeters are divided into two categories: throttling type and bypass type. Throttle type includes standard type (orifice plate, nozzle and Venturi tube) and non-standard type (slotted orifice plate, perforated plate, 1 / 4 orifice plate, elbow, conical inlet orifice plate, etc.). The flow around type includes annular orifice plate, annular channel (V-shaped inner cone, channel type, etc.), uniform veloci...

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Problems solved by technology

[0003] The standard orifice throttling device has the advantages of simple structure, mature application technology, and standardized products. It is the most widely used flow meter in industry at present; but it also has many disadvantages: the permanent pressure loss is too large, and installation requires upstream and downstream equipment. Long straight pipe section, narrow range ratio, only 3:1, passivation of the edge of the opening will reduce its accuracy, the flow stream must be parallel to the pipe axis before the fluid flows through the throttling device, and there must be no rotating flow, etc.

Although the pressure loss of the nozzle and Venturi is 30% to 50% lower than that of the orifice plate at the same flow rate and β value, the nozzle and Venturi are expensive and the structure is more complicated

[0004] The elbow flowmeter is a differential pressure flowmeter that uses the pressure difference between the inside and outside of the elbow to measure the flow rate. Its advantages are low cost, easy installation and use, and its disadvantage is that it is prone to secondary flow interference. The influence of the pipe structure size parameter R / D is very sensitive, so it is not easy to achieve standardization

[0005] For the measurement of multiphase flow, the elbow flowmeter cannot realize it, and due to the complexity of the flow conditions of the two-phase fluid, the orifice, the nozzle, and the Venturi cannot borrow a unified empirical formula, and the combined method is generally used for measurement, such as Li The double-slot orifice combination proposed by Yuxing et al., the Venturi tube-vortex flowmeter combination proposed by Zhiqiang Sun, the slotted orifice-swirl flowmeter combination proposed by Chenquan Hua, etc., the orifice plate or Venturi tube proposed by C.H.Hong et al. -Critical flow nozzle combination, Venturi tube-laminar flowmeter combination proposed by ShunpeiYamazaki, etc. These methods can work normally within a certain range, but once the measurement range is exceeded, the flow signal will be submerged in a strong " Noise", the measurement error will increase sharply and even fail to work

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