Application of New Field Instruments in Key Operational Conditions of Chemical Plants 1 INTRODUCTION In the modern production process, automation acquires, converts, displays, and transmits various types of information through process detection instruments (material temperature, pressure, flow rate, composition, stationary equipment). The level, interface, vibration amplitude, speed, acceleration, rotation speed, displacement, etc. of the rotating equipment, and then processed by the process control system (DCS, ITCC, etc.) to command, control the valve, etc. The purpose of automation of the production process is to keep the process parameters at the required values ​​and the equipment is in optimal working condition. In terms of process instrumentation and regulating valves, they are like human "five features" and "four limbs." If the control parameters cannot be detected and adjusted effectively and accurately, the control becomes passive water and wood without a root. Since the beginning of the 21st century, the development of new process detection instruments and control valves, represented by radar level gauges and labyrinth valves, has become more and more mature, and applications have become more widespread, especially in response to chemical engineering devices and to solve various complex, harsh and critical tasks. In the situation, remarkable results have been achieved. Air Furniture,Inflatable Air Bed,Air Sofa Bed,Air Sofa P&D Plastic Manufacture Co., Ltd , https://www.jmpoolfloat.com
2 Radar level gauge 2.1 The measurement principle is shown in Fig. 1. Taking a cable guide radar level gauge as an example, the measurement principle is based on the time travel, that is, the instrument measurement is from the reference point (the instrument process connection point) to the liquid The distance from the surface: The probe emits high-frequency radar waves and propagates along the cable. When the radar wave meets the surface of the liquid level, it is reflected back by the receiver in the instrument. Compared with the instant of signal transmission, the frequency of the signal changes. The frequency is slightly different. The frequency difference is proportional to the distance to the liquid surface and can be calculated accurately, whereby the level height value is measured.
Fig.1 Radar Level Gauge http://Measurement Principle Diagram 2.2 Structural Features 1) Irrespective of factors such as medium density, temperature, pressure, etc., high measurement accuracy and wide application;
2) No moving parts, high reliability and maintenance-free;
3) According to the equipment requirements can choose a variety of installation methods, flexible and adaptable;
4) Parameters can be configured by various methods such as LCD head, handheld smart terminal, and computer software, which is convenient for debugging;
5) The use of dedicated software can complete the instrument configuration, data protection, signal analysis, file processing and other functions, analysis and diagnostic functions;
6) The electronic components are integrated in the display head, which can be disassembled and exchanged online, and the maintenance is convenient.
Selection and installation using E+H company's cable intelligent HART Guided Wave Radar Level Gauge (FMP40 type), process interface flange is DN40, pressure rating is PN40, material is 316L, cable length is 23.5m, diameter is 6mm, The material is 316, with a separate display (installed on the tank floor, cable length of about 30m), measuring range is 20m. The radar level gauge is installed on the top of the ammonia tank, and a short DN150×2m pipe is installed on the top of the cable, and the middle ring is used to limit the position. The bottom end probe is bolted to the bottom of the tank body and grounded.
Effect The radar level gauge was installed and put into operation during ammonia tank cleaning during the system overhaul in March 2006. Its measurement signal was introduced into the DCS for display and alarm, and ESD was also introduced for interlock protection. The measurement is stable and normal. It is reliable and accurate. In 2011, it was replaced with a meter failure. Basically it is maintenance-free.
Boiler steam drum working condition overview The actual case is the boiler boiler steam drum, the design temperature is 370 °C, and the design pressure is 3.85 MPa (gas phase layer). The drum used electrode type level switch, float switch and differential pressure transmitter to measure, alarm and interlock in the past, then cancelled electrode type liquid level switch, added rod type guided wave radar level gauge, adopted 2oo3 logical voting method. Low level interlock protection.
Selection and installation of Rosemount's Smart HART rod guided wave radar level gauge (3301HTHP type), process interface flange is N50, pressure rating is ANSI600#, material is 316, probe length is 800mm, diameter is 6mm, material 316, measuring range is 500mm. The temperature-pressure curve of the high-temperature and high-pressure radar level gauge is shown in FIG. 2 . The radar level gauge is installed in the bypass measurement cylinder and is constrained by a centering ring at the end of the probe.
Effect The radar level gauge was installed and put into use during the system overhaul in June 2007. The measurement has been stable, normal, reliable and accurate since use and has not been overhauled.
2 Compressor surface condenser 905-C, design temperature is 48°C, design gauge pressure is -85kPa (vapor phase layer). The ammonia tank used a pneumatic buoy type liquid level gauge to measure. Because it can not be used normally under high vacuum conditions, it was later changed to a radar level gauge and the measurement signal was introduced into DCS for display, alarm and interlock.
Selection and installation of KOE's smart HART cable guided wave radar level gauge (FMP40 type), process flange interface is DN50, pressure rating is ANSI150#, material is 316, probe length is 560mm, diameter is 6mm, material 316, measuring range is 550mm. The radar level gauge is installed in the bypass measuring cylinder with a diameter of 2′′. The process interface is 1-1/2′′, and the center of the probe is limited by the centering ring.
Effect The radar level gauge was installed and put into operation during the system overhaul in August 2008. The measurement has been stable, normal, reliable and accurate since use, and has not been overhauled.
The actual situation of the crystallization medium working condition is the urea device S403/404 liquid level measurement, the medium is urine, the design temperature is 168°C, and the design gauge pressure is 1.85 MPa (gas phase layer). The ammonia tank used a double-flange liquid level transmitter to measure. Due to serious crystallization and inaccurate measurement, it was later changed to a rod-type guided wave radar level gauge.
Selection and installation using E+H's smart HART rod guided wave radar level gauge (FMP41C type), process flange interface is DN50, pressure rating is ANSI300#, material is 316L, probe length is 550mm, diameter is 6mm , material 316L, measuring range is 1300mm. The radar level gauge is installed inside the bypass measuring cylinder with a diameter of 3′′ (jacketed steam heating trace), the process interface is 1-1/2′′, and the center of the probe is limited by the centering ring.
Effect The radar level gauge was installed and put into operation during the system overhaul in May 2009. In 2011, due to problems with the probe and the display head seal, media leakage occurred, resulting in decreased insulation of coaxial connectors and corrosion of electronic components. After the rectification of the seal, it is operating normally. The measurement is stable, normal, reliable, and accurate so far. It basically belongs to the maintenance-free state.
3 Labyrinth valves In chemical plants, there are many severe working conditions such as high pressure difference and high flow rate. There are factors such as cavitation and flashing that cause great damage to the regulating valve. The internal structure of a multi-stage pressure-reducing valve such as a labyrinth valve is used. Regulating valves can effectively solve such problems and obtain greater economic benefits.