Principle and design of wet steam flow metering device

Contents

The utility model relates to a flow metering device, in particular to a wet steam flow metering device.

Background of the Invention

Most of the primary energy is converted into steam for utilization. Steam is divided into saturated steam and superheated steam. Superheated steam is obtained by heating saturated steam. Superheated steam does not contain droplets or liquid mist and belongs to actual gas. After long-distance transportation, superheated steam will enter the saturated state from the superheated state due to heat loss and temperature reduction as the temperature and pressure change, especially when the superheat is not high. Saturated steam is easy to condense. If there is heat loss during the transmission process, droplets or liquid mist will form in the steam, that is, it becomes wet saturated steam. Wet saturated steam is no longer a gas in the strict sense, and its density has also changed greatly. For wet saturated steam, inaccurate measurement has always been a difficult problem to overcome. The main error comes from the fact that the density of two-phase steam changes in time with the change of working conditions, and cannot be accurately calculated. At present, the flow metering device on the market can only be applied to single-phase superheated steam, and the error is large when measuring wet saturated steam. In view of the above defects, it is necessary to design a wet steam flow metering device.

Summary of the invention

The technical problem to be solved by the utility model is to provide a wet steam flow metering device to solve the problem of large metering error caused by timely change of wet saturated steam density.

To solve the above technical problems, the technical solution of the utility model is: a wet steam flow metering device, including a nozzle flowmeter, a main pipe, an intake pipe, a return pipe, an outer insulation pipe, an inner insulation pipe, a heating pipe, a sampling inlet pipe, a first temperature sensor, a pressure sensor, a connecting pipe, a second temperature sensor, a venturi flowmeter, and a sampling return pipe. The main pipe is located on the left side of the nozzle flowmeter, and the main pipe is threadedly connected to the nozzle flowmeter. The intake pipe is located at the upper end of the main pipe, and the intake pipe is threadedly connected to the main pipe. The return pipe is located at the upper end of the main pipe and on the right side of the intake pipe. The return pipe is threadedly connected to the main pipe and movably connected to the intake pipe. The outer insulation pipe is located at the upper end of the intake pipe and at the upper end of the return pipe. The outer insulation pipe is threadedly connected to the intake pipe and threadedly connected to the return pipe, and the inner insulation pipe is located on the inner side of the outer insulation pipe.

The inner insulation pipe is welded and connected to the outer insulation pipe, the heating pipe is located on the inner side of the inner insulation pipe, the heating pipe is threadedly connected to the inner insulation pipe, one end of the sampling inlet pipe is located at the upper end of the main pipe, the sampling inlet pipe is threadedly connected to the main pipe, the other end of the sampling inlet pipe passes through the outer insulation pipe and the inner insulation pipe, the sampling inlet pipe is threadedly connected to the outer insulation pipe and the inner insulation pipe, the first temperature sensor is fixedly connected to the intake pipe, the pressure sensor is fixedly connected to the intake pipe, the connecting pipe is located on the right side of the outer insulation pipe, the connecting pipe is threadedly connected to the outer insulation pipe, the connecting pipe is also provided with a second temperature sensor, and the second temperature sensor is threadedly connected to the connecting pipe, the venturi tube flowmeter is located on the right side of the connecting pipe, the venturi tube flowmeter is threadedly connected to the connecting pipe, the sampling reflux pipe is located on the right side of the venturi tube flowmeter and at the upper end of the main pipe, the sampling reflux pipe is threadedly connected to the venturi tube flowmeter and the main pipe.

The utility model is further improved as follows: the number of the heating pipes is 4, evenly distributed in the inner insulation pipe. The air intake pipe is also provided with a first solenoid valve, which is threadedly connected to the air intake pipe. The air return pipe is also provided with a second solenoid valve, which is threadedly connected to the air return pipe. The sampling inlet pipe is also provided with a third solenoid valve, which is threadedly connected to the sampling inlet pipe. The sampling return pipe is also provided with a fourth solenoid valve, which is threadedly connected to the sampling return pipe.

Compared with the prior art, the wet steam flow metering device, when working, wet steam enters the main pipe through the nozzle flow meter, wet steam enters the inner insulation pipe through the sampling inlet pipe, the heating pipe heats the wet steam, and the heated superheated steam flows back to the main pipe through the connecting pipe, the venturi tube flow meter and the sampling return pipe in succession. At the same time, the steam in the main pipe enters the cavity between the outer insulation pipe and the inner insulation pipe through the air inlet pipe for insulation, and then flows back to the main pipe through the return pipe. The nozzle flow meter measures the differential pressure when the wet steam flows through the nozzle flow meter. The first temperature sensor and the pressure sensor are used to measure the temperature and pressure of the wet steam before heating, the second temperature sensor and the pressure sensor are used to measure the temperature of the superheated steam after heating, and the venturi tube flow meter is used to measure the wet steam pressure and pressure difference in the main pipe. According to the test data, the wet steam flow can be calculated. The device has a simple structure, and the wet steam is converted into superheated steam by heating, and there is no need to separate the gas and liquid phases. The density of the wet steam after heating is uniform, which effectively improves the measurement accuracy.