CN102589934A - Oxygen concentration measurement sampling flow compensation device of air flow conveying system - Google Patents

Abstract

A sampling flow compensation device for oxygen concentration measurement in a pneumatic conveying system comprises an oxygen analyzer, a nitrogen generator, and a centrifuge. Valve V5, valve V6, valve V7, a regulating and pressure-reducing valve V8, and a linear vacuum generator are added to the sampling channel of the oxygen analyzer and are linked with valves V2, V5, V6, and V7. This invention employs a linear vacuum generator to effectively compensate the pressure of the sampling airflow of the oxygen analyzer in the pneumatic conveying equipment, establishing a relatively stable sampling flow in the system to maintain real-time monitoring and signal conversion by the analyzer. This overcomes the influence of various interference factors in the system, enabling the analyzer to track changes in oxygen content within the system in a timely manner, reducing nitrogen consumption, and ensuring continuous system production.

Description

An oxygen concentration measurement sampling flow compensation device for an airflow delivery system

the

technical field

The invention relates to an oxygen concentration measurement and sampling flow compensation device for an airflow conveying system.

Background technique

In the production process of powdered pharmaceuticals, in order to reduce human errors/avoid contact between the human body and materials, air conveying equipment is widely used in the production of pharmaceuticals and food. The dilute phase positive and negative pressure mixed conveying equipment involved in the production of the airflow conveying system in this article is used to convey the crystal powder, the airflow is recycled, and the material is thrown into the system through the centrifuge, and there is still residual solvent gas. In the event of combustion or explosion, a GE oxygen analyzer/nitrogen compensation system is added to the system to control the oxygen concentration in the system between 4-6%.

As shown in Figure 1, the air flow power in the system is provided by the Roots blower. After the material is spun off by the centrifuge, it enters the material bin for temporary storage. Three material level gauges are installed in the bin, which are HW high/MW middle/ LW low material level detection, when the oxygen content in the system is less than 6% and there is a high or medium material level in the silo, the valve V2 is opened, the system starts to feed the material, and the material enters the cyclone separator to be separated and sent to the downstream through the valve V4 Dryer equipment, the airflow entering the cyclone separator passes through the dust bag and is sucked by the Roots blower for recycling.

When the oxygen content in the system exceeds 6%, the system will stop feeding for nitrogen supplementation. The air compressor provides compressed air, and after the nitrogen generator generates nitrogen, it enters the storage tank for storage. Oxygen content detection devices are installed before and after the Roots blower --- XM02 oxygen concentration analyzer produced by GE Company. PLC. During normal material transportation, there is material in the pipeline, and there is a pressure difference of about 150mbar before and after the fan. The sampling flow rate is adjusted and controlled at 200cc/min. When the feeding is stopped or nitrogen is replenished, the pressure difference between the front and back of the fan will become very small. When the system is replenishing nitrogen, the valve V2 is closed to stop the material delivery, the valves V3 and V1 are opened, nitrogen enters the system, the pressure difference between the front and back of the fan decreases, and the flow rate of sampling detection decreases. 2.0SCFH (50-1000cc/min) fluctuations in the range of values, but when the flow rate decreases to a trace value, or even zero, the oxygen content detection will show hysteresis. The nitrogen production system adopts the principle of carbon molecular sieve pressure swing adsorption to produce nitrogen. The purity of nitrogen is related to the pressure. When the pressure of nitrogen is low, the purity of nitrogen will decrease. When the system is replenishing nitrogen, if the detection lag causes the pressure of the nitrogen storage tank to drop to a low value, and the PLC cannot stop the nitrogen replenishment command when the oxygen concentration is not up to the standard, the nitrogen purity in the air delivery pipeline will always be at a low value. The program will thus stall.

The stagnation of the above-mentioned system rarely occurs in daily production. The system is an automatic production equipment and no one operates it. However, once it occurs, although there is an alarm signal, it will take a long time for the operator to find out. Analyzing the failure phenomenon, the sampling flow rate decreases sharply when nitrogen is supplemented, which leads to the detection lag of the oxygen analyzer, which is the root cause. The loading/unloading interval of the air compressor is not suitable, resulting in too much pressure change of the air compressor, or the pressure setting value is too small, which will directly affect the purity of nitrogen production; the change of the air permeability of the filter bag during the material transportation process, and the leakage of the system pipeline All of these factors will further interfere with the measured value of the oxygen content at a smaller sampling flow rate, resulting in irregular timing of failure/instability of the system.

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Invention content:

The object of the present invention is to provide a flow compensation device for oxygen concentration measurement and sampling in an airflow conveying system, which can overcome the above problems existing in the existing equipment. The object of the present invention is achieved like this, a kind of gas flow delivery system oxygen concentration measurement sampling flow compensator, comprises oxygen content analyzer, nitrogen machine, centrifuge and is made up of, it is characterized in that: set up valve in the oxygen content analyzer sampling channel V5, valve V6, valve V7, regulating decompression valve V8 and linear vacuum generator are linked with valve V2, valve V5, valve V6 and valve V7. The present invention adopts a linear vacuum generator to effectively compensate the pressure of the sampling air flow rate of the oxygen content analyzer of the air flow conveying equipment, and establish a relatively stable sampling flow in the system to maintain the real-time monitoring and signal conversion of the analyzer and overcome the The influence of various interference factors in the system is eliminated, so that the analyzer can track the change of oxygen content in the system in time, reduce the consumption of nitrogen, and ensure the continuous production of the system.

the

Description of drawings:

Fig. 1 is a schematic diagram of the traditional equipment structure;

Fig. 2 is a structural representation of the present invention;

1. Air compressor, 2. Nitrogen machine, 3. Nitrogen storage tank, 4. Valve V1, 5. Valve V3, 6. Centrifuge, 7. Material bin, 8. Discharge screw, 9. Valve V2, 10. Roots blower, 11. Oxygen analyzer, 12. Cyclone separator, 13. Valve V4, 14. Intermediate hopper, 15. Valve V9, 16. Dryer, 17. Valve V6, 18. Valve V5, 19. Linear vacuum generator, 20. Valve V7, 21. Regulating pressure reducing valve V8.

The specific embodiment: the present invention will be further described below in conjunction with accompanying drawing;

An oxygen concentration measurement sampling flow compensation device for an air flow conveying system, comprising an oxygen content analyzer, a nitrogen machine, and a centrifuge, is characterized in that: a valve V5, a valve V6, and a valve V7 are added to the oxygen content analyzer sampling channel. Pressure reducing valve V8 and linear vacuum generator are linked with valve V2, valve V5, valve V6 and valve V7. During specific implementation, when feeding, valves V2 and V6 are opened, valves V5 and V7 are closed, and the linear vacuum generator does not work. At this time, the sampling flow of the oxygen analyzer is obtained through the pressure difference between the front and rear of the fan; when the valve V2 is closed, the feeding is stopped, and the valve V5 , the valve V7 is opened, the linear vacuum generator works, and the pressure reducing valve V8 is adjusted to keep the sampling flow of the oxygen content analyzer constant at 200 cc/min; when nitrogen is supplemented, the valves V1, V3, V5, and V7 are opened, The content analyzer will maintain a relatively stable sampling flow, and transmit the instant value of oxygen content in the system to the PLC in time, saving a lot of nitrogen and maintaining the continuity of production.

Claims (1)

1. a flow delivery systems oxygen concentration is measured the sampling flow compensation system; Comprise that oxygen analysis appearance, nitrogen machine, hydro-extractor form; It is characterized in that: in oxygen analysis appearance sampling passage, set up valve V5, valve V6, valve V7, regulate reduction valve V8 and linear vacuum generator, and link with valve V2, valve V5, valve V6, valve V7.

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