Based on the working principle of magnetic flap level gauge, this paper analyzes the magnetic flap level gauge measurement error due to external factors, and put forward the corresponding improvement scheme according to these factors. The actual operation results show that the magnetic level gauge turning negative pressure within the lateral line after the accumulation of bubbles is eliminated, the measuring error controlled within 3%, and smooth liquid level display.
Magnetic flap liquid level meter is a kind of non-contact level measurement instrument, the output pressure can automatically follow the blow pipe outlet pressure change and change, and maintain a stable output gas flow, by measuring the pressure differential between the blow pipe is measured and measure the liquid level of tank. Magnetic flap liquid level gauge is suitable for high temperature and high vacuum, high viscosity, strong corrosion resistance, easy to solidification, easy to crystallization, or containing suspended particles of polymer melt, etc all kinds of bad working condition.
Reactor is a kind of important chemical machinery equipment, and chemical machinery equipment is a chemical enterprise basic material safeguard normal production activities, it directly affects the enterprise production planning and product delivery time, in the event of level measurement inaccuracies resulting in failure of mechanical equipment, can affect the completion of the production plan of enterprise expected. At present, the magnetic flap liquid level meter is generally used in the chemical industry in the reactor liquid level measurement, therefore, in order to ensure the magnetic level gauge measurement accuracy, turning to reduce the magnetic flap level gauge measurement error method to explore is very necessary. Magnetic flap in this, the author of the level of external factors were analyzed, and the measurement error and put forward the corresponding improvement measures, to reduce the magnetic flap level gauge measurement error.
Magnetic flap liquid level meter using the statics principle, through the differential pressure transmitter is the pressure of the suction side, forming a certain pressure difference, realize measurement of solution density and liquid level in the reactor. The working principle of a magnetic flip chart is shown in figure 2. A certain amount of dry hydrogen through the rotameter into 9/16 inch (1 inch = 33. 333 mm) of the positive pressure side within the capillary, makes the micro bubble overflow pipe, and then according to the type (2) to calculate the reactor without the liquid level. At the same time, in the chemical production of concrete using magnetic flap liquid level gauge measuring reactor, magnetic flap liquid level meter capillary suction side should avoid liquid enters, otherwise it will cause false phenomenon of liquid or liquid into the phenomenon of transmitter, lead to measure error and even damage the instrument.
The measuring error of the liquid level of the magnetic flip plate is analyzed in the process of chemical production, and the measuring accuracy of the meter is very high. In the course of the use of the flip plate, some external factors will cause the error to be measured.
2.1 solution bubble
Bubbles are the dispersed systems of gas and liquid, which are usually dispersed by gas through the holes in the process. In a fixed bed reactor, the gas is exposed through a gas distributor at the bottom of the reactor and dispersed through the solution layer. The formation of bubbles is divided into the incubation stage, the stage of adulthood and the stage of departure. During the incubation phase, the gas pressure has a build-up process that can form bubbles when the capillary pressure is reached. Bubbles have a gas-liquid contact interface, have specific mechanical properties on the interface, when bubbles dissolved or grew up, gas-liquid interface mass transfer will happen, and the bubble size change will drive the solution flow. These three processes interact with each other, so the bubbles are a dynamic system of interface-mass - flowing coupling.
As the solution containing large amounts of water in the reactor, when the reaction temperature or temperature has not been achieved not timely coexist in oily solution, water and gas flow, easy to produce bubbles. Bubble after the agitation of the gas flow from bottom up, rising, and on the suction side of the gauge tube in a large number of accumulation, into the pipe, so as to make the pipe has large bubbles exist. When a large number of bubbles are gathered into the horizontal tube, it cannot be discharged, causing the false liquid surface phenomenon, which leads to the measurement error. In the process of chemical production, the reactor in the second level gauge (radar level gauge) as a general reference group, through the comparison, DCS monitoring judgment magnetic flap liquid level measurement is accurate. When magnetic level gauge turning a lots of bubbles in the suction side of the line, the measurements are volatile, no rules to follow, according to the level of increase or decrease values also do not have any trend, serious when value directly from the current level jumped 100%, or 0%, has greatly dangerous chemical production, reduce the production efficiency.
2.2 containers of external piping are frozen
In the cold winter, at the top of the reactor external negative pressure inside the pipeline, because inside the reactor temperature is higher, the outside temperature is low, the temperature difference is very big, so the tube is highly vulnerable to bubbles condensation and ice, and adhere to the tube, frustrating measuring the differential pressure transmitter. In severe cases, the fluid enters the transmitter, which will cause the transmitter to freeze and damage, resulting in the failure of the liquid-level gauge to measure the level of the liquid.
