Multipoint thermocouple how to install? Installation method have? Release date: 2019 04 - 08 viewed: zero1

Multi-point thermocouples are suitable for the production site where the temperature gradient is not significant, and it is necessary to measure multiple locations or multiple measurements at a single location at the same time. Multi-point thermocouples are widely used in large fertilizer synthesis towers, storage tanks and other devices.

Why do multipoint thermocouples have explosion-proof characteristics?

If a closed circuit is composed of two homogeneous conductors (thermoelectrodes) of different components, when there is a temperature gradient at both ends, there is a current passing through the circuit, then there is a thermoelectric potential between the two ends. , Design a junction box and other components with sufficient strength to seal all parts that will generate sparks, arcs and dangerous temperatures in the junction box. When an explosion occurs in the cavity, it can be extinguished and cooled through the gap between the joints to make the explosion The flame and temperature do not pass outside the cavity.

Application of multi-point sheathed thermocouple in the temperature measurement of hydrogenation reactor bed

In the fixed-bed hydrogenation unit, the reactant stream enters from the top of the reactor. Under the action of the catalyst, a chemical reaction occurs between the materials and heat is released. Therefore, there is a temperature rise of the catalyst bed along the axis of the reactor. When the inlet distributor of the catalyst bed is not well designed, the structure of the catalyst part is damaged, and the process conditions change greatly, the temperature at different positions on a certain cross section of the bed may also be different, that is, the radial direction of the catalyst bed Temperature rise. When the reaction temperature rises too high and is not controlled, it may cause the following consequences:

a) A high temperature reaction zone is formed in the reactor. The reactant stream reacts violently in the high temperature zone, releasing more reaction heat, making the reaction temperature higher. Such a vicious circle may damage the catalyst, and may even cause the catalyst bed to fly over temperature and cause an accident.

b) The catalyst is gradually deactivated with the passage of time. When the reaction temperature is increased to compensate, the catalyst near the high temperature zone in the lower part of the reactor will reach the designed maximum operating temperature prematurely and will be forced to stop. However, the catalyst in the low temperature zone at the upper part of the reactor still has high activity and is not used, which affects the economic benefits of the device.

c) It is unfavorable to product quality and selectivity. In the hydrotreating reaction, when the reaction temperature increases to a certain value, the equilibrium conversion rate decreases, so that the denitrification rate and the aromatic saturation rate decrease, and the product quality decreases. In the hydrocracking reaction, an excessively high reaction temperature will accelerate the secondary cracking reaction, resulting in a decrease in fraction selectivity and an increase in gas production. Therefore, both the axial temperature and the radial temperature of the reactor must be detected. The more uniform and detailed the distribution of temperature measurement points, the more comprehensive the changes in the bed temperature in the reactor can be reflected.

Main parameter reference of multi-point explosion-proof thermocouple

Electrical outlet: M20x1.5NPTI1/2

Thermal response time: ≤8S Couple wire diameter: Ф1. Ф2. Ф3

Protection level: IP65

Flameproof grade: d‖BT4.d‖CT5

The working principle of multi-point thermocouple

The original explosion-proof uses the principle of gap explosion-proof, designing junction boxes and other components with sufficient strength, and all parts that generate sparks, arcs and dangerous temperatures are sealed in the junction box. When an explosion occurs in the cavity, it can pass through the gap of the joint surface Extinguish and cooling, so that the flame and temperature after the explosion do not pass to the outside of the cavity.