Vessel, comprising a thermocouple sensing structure for measurement of a temperature distribution inside of the vessel preferably filled fully or partially with multi-phase fluid consisting of residue oil, hydrogen, cracked oil/gas products, sulfur, catalyst particles or catalyst droplets, etc., - the thermocouple sensing structure consists of a support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62) and a number of thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32), wherein - the vessel contains one or more levels of support structures (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62), - the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) each have a measuring point at a closed tip which is fixed inside the vessel by the support structures (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62), - each thermocouple sensing element (3, 3B, 3C, 3D, 3L, 32) together with other thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) passes through a sealed port into the vessel, - a connecting end of each thermocouple sensing element (3, 3B, 3C, 3D, 3L, 32) is electrically connected outside of the vessel to a process control system, and - the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) are partially or fully covered by the support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62), characterized in that - the closed tip of the thermocouple sensing element (3, 3B, 3C, 3D, 3L, 32) is passed through the support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62) to the inside of the vessel, - the support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62) has a protection portion for covering the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) and a support element for distribution of the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32), - a tip of the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) is fixed to a special point within the vessel, - the support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62) is reinforced by one or more additional elements and - the one or more additional elements are a trapezoidal limiting-fixation element (21, 21S, 21T, 23, 23B, 23C) or a cylindrical limiting-fixation element (21, 21B, 21C, 23, 23B, 23C). - the thermocouple sensing structure consists of a support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62) and a number of thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32), wherein - the vessel contains one or more levels of support structures (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62), - the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) each have a measuring point at a closed tip which is fixed inside the vessel by the support structures (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62), - each thermocouple sensing element (3, 3B, 3C, 3D, 3L, 32) together with other thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) passes through a sealed port into the vessel, - a connecting end of each thermocouple sensing element (3, 3B, 3C, 3D, 3L, 32) is electrically connected outside of the vessel to a process control system, and - the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) are partially or fully covered by the support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62), characterized in that - the closed tip of the thermocouple sensing element (3, 3B, 3C, 3D, 3L, 32) is passed through the support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62) to the inside of the vessel, - the support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62) has a protection portion for covering the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) and a support element for distribution of the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32), - a tip of the thermocouple sensing elements (3, 3B, 3C, 3D, 3L, 32) is fixed to a special point within the vessel, - the support structure (1, 11, 12, 12B, 12C, 20C, 21K, 23A, 23B, 34B, 34D, 61, 62) is reinforced by one or more additional elements and - the one or more additional elements are a trapezoidal limiting-fixation element (21, 21S, 21T, 23, 23B, 23C) or a cylindrical limiting-fixation element (21, 21B, 21C, 23, 23B, 23C).