Talk about multiple thermocouples and thermal resistors

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This post was last edited by Sai Xin on 2022-2-25 at 15:07. I’ve retrieved an article I wrote for the company newspaper in the past, made some minor revisions to it, and published it again so that my colleagues can read it. As China’s manufacturing capabilities for temperature sensors improve, our regular electronic temperature products are facing increasing competitive pressure； On the other hand, there are still some special temperature sensors, including multi-point thermocouples/thermoresistors, thermocouples capable of withstanding extremely high temperatures as well as wear and corrosion, and sensors with special protective coatings. These are technologies that most domestic manufacturers are not yet able to develop at present; they will become the key products of our Suzhou Saixin Automation Co., Ltd., serving as the core elements for achieving our three-year plan. This article will introduce some information related to multi-point thermocouple/thermistor products. A multi-point temperature sensor is a set of temperature sensors that are connected through the same process and run across the pressure-bearing interface, allowing the temperature at several points to be measured on one side; it is commonly used in reactors and storage tanks. Due to their large size, the temperature measured is very important (especially for applications involving catalyst temperature monitoring and metering in storage tanks), and since the price of these products (when imported) is high, the concept of \"multiple measurement points\" always seems mysterious to users as well as design firms and engineering companies. “Compared to conventional single temperature sensors, the \"multi-point\" design obviously saves installation space; more importantly, it enhances safety. In many cases, it is necessary to measure the temperature at various points within the reactor. One can imagine whether it is better to make several holes in the reactor and install a single thermal resistor/thermocouple in each hole, or to make just one hole and use a multi-point sensor, especially for reactors that operate under high temperatures and pressures. Refining is an important industry with multiple applications; processes such as crude oil distillation, hydrogenation, and catalytic reforming all make use of multiple points ； In the fields of chemical engineering and fine chemicals, including currently popular applications such as propane dehydrogenation and acrylic acid production, multi-point thermoresistors/thermocouples are also widely used. In the refining industry, multi-point import brands such as Gayesco and Daily entered China early and have already achieved significant results there. In particular, they have entered into cooperation agreements with many patent providers (such as UOP, etc.) to incorporate multiple points into the patent design. The core product is a flexible multi-point thermocouple made of material 347, with an enhanced armored casing; it is installed along the interior of the reactor or its internal supports, and theoretically enables temperature measurement at any point within the reactor volume. It is used to monitor the catalyst temperature and ensure reactions take place at maximum efficiency. We also need to further enter this industry and increase the awareness of our products. It’s important to note that we manufacture our products at multiple locations within the country, which reduces costs – especially transportation costs – making us more competitive. The pandemic abroad has also caused delays in the delivery times of imported products. In the chemical industry, where multi-point applications are not as concentrated, especially the mini multi-points on shell-and-tube reactors (temperature measurements at different locations along a given direction), Gayesco and Daily are rarely involved. This is an industry that deserves our attention, given the large number of chemical projects in China. At present, some of the multi-site orders we have received are also concentrated in the chemical industry, including polysilicon projects in Inner Mongolia, coal chemical projects in Xinjiang, and succinic anhydride/acrylic acid projects in Jiangsu. Putting design aside, there are two technical aspects that are crucial in the multi-point manufacturing process. The first is the welding process: argon arc welding of the armored thermocouple to the flange (for manufacturers who are not capable of welding, clamping fixtures must be used for sealing). . ） ； The second is product testing. Especially in terms of testing, a complete set of testing methods including hydrostatic testing, liquid dye testing, composition analysis, X-ray inspection, and ultrasonic testing are things that domestic manufacturers generally find difficult to achieve. Our factory’s full diamond sleeve production line has reached a certain scale, and it is equipped with all these testing methods. Multi-point temperature sensors are special and of high value; many clients request it, or we recommend it on our own initiative, to provide on-site installation guidance. Xu’s team traveled across the north, south, west, and east, braving various challenges; with their extensive experience, they managed to drill 20 holes per person in the reactors, providing guidance on installation and debugging to ensure the perfect delivery of the products. Flexible armored multi-point and mini multi-point thermocouples with a secondary protection chamber typically allow 20–30 measurement points to be installed in a protection tube with a diameter of 6 mm, while 10 points can be placed in a tube with a diameter of 3 mm. They are used in shell-and-tube reactors as well as in pilot and laboratory-scale devices. The mini multi-point version with a length of 12 meters can still be transported by truck, thanks to luck