The use of clamp-on ultrasonic flow metering for concentration measurement of nitric acid, an ingredient for our fertilizer plants, has led to better accuracy and lesser dependence on lab analysis, says Mahesh Patil, General Manager - Instrumentation, Deepak Fertilisers & Petrochemicals Corporation Limited (DFPCL) while outlining how the use of this technology has also reduced the sampling frequency.

"Among the major challenges in the plant setup are the large flow volumes that are difficult to quantify and the lack of straight pipe runs in the available piping system. The fluid that contains particles can interfere with the flow measurement and lead to inaccurate data. Also, the fluids that are abrasive, corrosive or toxic can subject the flow instrument to wear and tear. The entering of air into fluid is a challenge because the flow will be erratic if such a condition occurs," says Patil. 

"When a fluid contains coating, it can result in its deposition on the electrodes of the magnetic flow meter, leading to erratic meter readings and even malfunctioning. With regard to such challenges, ultrasonic flow meters have many advantages as it is non-contact and can be used for abrasive and corrosive chemicals for flow measurement. Since it is non-intrusive, there are minimal interferences with the process. There is no need for process shutdown for its installation. We were earlier dependent on lab analysis for release of a batch but now with availability of the real time concentration analysis, the quality of a batch has increased," adds Patil.

Patil shared his thoughts alongside other experts from leading chemical companies at the E-conference on 'Non-intrusive Flow Measurement and Process Analytics Solutions in Chemical Plant' organized by the Indian Chemical News on September 16, 2021. The highly insightful session was moderated by Pravin Prashant, Editor, Indian Chemical News.

R. S. Rajan, Senior Vice President - Manufacturing, Meghmani Finechem says, "Every part of steam has to be quantified as it is highly essential to monitor its consumption. We have to take care of the best cost and maintenance to avoid frequent gas leakages. For that we have to stop the plant in that case and do the maintenance. During the commissioning of the plant, we ensure that we carry out steam blowing and achieve target radius. We also avoid any deposit on the internal linings of the pipes. We try to maintain the best quality of demineralized water (DM) water so that there is no stickiness on the floor of the plant. We use a differential pressure flow meter and due to the accumulation of condensate on lines, it used to show erratic readings. Based on operational experience, when we see the deviation in flow meter readings, we perform the maintenance. A few times, the temperature even goes upto 400 degrees celsius. The direct temperature reading is not possible and we are in the process of a direct flow meter that will measure at temperature. We use magnetic, mass and many other types of flow meters but cost factor and usefulness for specific operations are factors. Sometimes, sticky particles get stuck and affect readings. Comparatively, the Clamp-on flow meter with good sensors gives us digital output."  

Kanji Kumbharvadia, Senior Manager – Instrumentation, Navin Fluorine International says, "Right from in-line flow meters, we have many of the abrasive, corrosive and abusive meters but in case of Clamp-on flow meters we can minimize the direct touch of the metals as well as the contact parts of the flow meter with the process fluid. With this, we do the installation of any type of flow meter at any time required. We can do any type of maintenance at any time, just that we need to check the up and downstream requirements if any."

"At Navin, we have been using many types of raw materials but our main challenge is the hydrogen fluoride (HF) concentration. We are handling the HF fluid and we are also diluting this HF fluid for various pharmaceutical and agricultural products. Hence, while diluting, we need to take many samples to check whether the concentration is 20%, 30%, 50% or not. And this diluted hydro-chloric acid is very highly corrosive and poisonous with increased possibility of hazards. Clamp-on flow meters have many benefits for large pipeline sizes and installation of this technology has reduced a lot of such challenges," adds Kumbharvadia.

Vinod Patil, General Manager (Electrical, Instrumentation and Civil), Aarti Industries says, "One of the key challenges is the selection of Material of Construction (MOC) which is very vital for a device make up and second is application in line. If we install the in-line instruments, the maintenance is challenging for installed systems. There are solutions but they have their pros and cons. If we have in-line flow meters, we have to shut them down at times.Now a days all organizations have sustainability challenges. At Aarti, we have installed many devices to overcome these challenges. We have installed non-contact instruments for measurement of Sulfur trioxide (SO3) concentration."

Vivek Gupta, Joint VP - Instrumentation & Digitalization, DCM Shriram says, "Today everything is getting virtual. Instead of putting up measurement instruments inside the pipeline, the key trend is the type of devices that don't require the stopping of plants. The automatic cleaning types of concepts for measurements are becoming true. Earlier instruments were used just for measurements but now these are the decision making tools for management and the flow meter is very vital in an integrated system. Whatever flow meter operations we are doing, there are no leakages or choking should happen. The flow meter should be good enough to run the plant operations smoothly. In this regard, we are analyzing the portable Clamp-on the flow meter. Post installment, we are free of the issues and have got a lot of benefits from these instruments as it serves the purpose fully."

Listing out the advantages of Clamp-on ultrasonic flow metering and concentration measurement solution, Dr. Ingo Nickel, Head of Market Management for Chemical Industry, FLEXIM GmbH says, "There are no additional costs for special alloys as compared to inline devices, and there is no maintenance required. The reliability is a key factor that makes it unique as there are zero chances of deposits on sensors, no clogged capillaries, and measurements can be taken even with low flow rates while the measuring system is drift free. FLEXIM permanent ultrasonic measurement technology has robust sensors and it can operate under high temperature, pressure and corrosive conditions. We offer a series of product solutions made of suitable materials and sizes for various application ranges in liquids, gases and steam including measuring of concentration and density." 

Mathias Gehl, Global Analytics Sales Manager, FLEXIM GmbH says, "There are two major trends driving the flow meter globally. Big data is one of them and for that we need more data. To get more data, we need more accurate measurements on temperature and pressure. In this regard, our Clamp-on flow meter is a big help as it is very easy to install as it can be simply connected to the pipe in the factory. These are best suited for measuring density and concentration. Another factor is climate change as it will affect the industries across the countries, especially the places where energy costs aren't getting reduced. To deduce the Co2 footprint, we need the energy measurements and it is expensive to install normal flow meters on all pipelines. The simple customized Clamp-on flow meter can provide a cost effective solution in this case."