Dual-Stage Cooling for Multi-Tubular Reactor Temperature Control
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Solution Overview
Problem
Conventional multi-tubular reaction apparatuses face challenges in controlling heat medium temperature uniformly, leading to potential runaway reactions and catalyst deterioration due to time delays and overshoots in temperature control during catalytic gas-phase oxidation reactions, such as producing (meth)acrylic acid from propane or propylene.
Innovation Solution
A multi-tubular reaction apparatus with a dual-stage cooling system and a control system that adjusts the flow of heat medium by operating flow control valves in opposite directions to precisely control the temperature, allowing for continuous variation of the mixture ratio of heat medium flows to maintain stable reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the external circulation amount of heat medium is changed to control temperature, then the temperature uniformity is improved, but time delay and overshoot occur causing instability
Solution Approach 1:
The cooling water flow control is segmented into two independent control loops: one controlling the flow rate of cooling water to the heat exchanger, and another controlling the bypass flow rate. This segmentation allows each loop to respond independently to temperature deviations, eliminating the time delay and overshoot problems caused by single-loop control where changes propagate through multiple components sequentially.
2Object-affected harmful factors
If cooling load is increased to prevent runaway reaction, then reaction safety is improved, but temperature overshoot occurs due to control delay
Solution Approach 1:
The system performs preliminary cooling action by continuously maintaining both control loops in an active state, ready to respond immediately to temperature increases. The first control loop pre-adjusts the cooling water flow rate, while the second control loop pre-adjusts the bypass flow rate, ensuring cooling capacity is available before runaway conditions develop, thus preventing overshoot while ensuring safety.
3Loss of energy
If circulation amount is decreased to reduce cooling, then energy consumption is reduced, but catalyst life deteriorates due to hot spot formation
Solution Approach 1:
The system applies local quality control by independently adjusting cooling intensity in different flow paths. The first control loop provides localized cooling control through the heat exchanger, while the second control loop manages localized bypass flow. This allows precise control of cooling distribution, ensuring adequate cooling at catalyst locations to prevent hot spots and extend catalyst life, while optimizing overall energy consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables precise temperature control of the heat medium, preventing runaway reactions and catalyst deterioration, and achieving stable high-yield production by quickly adjusting to temperature fluctuations, even under changing conditions.
Implementation Method 1
a multi-tubular reactor, which comprises a shell and a plurality of reaction tubes provided in the shell and filled with a catalyst, and in which a heat medium circulates in the shell
Implementation Method 2
a heat medium circulates in the shell
Implementation Method 3
a cooling apparatus for the heat medium, the cooling apparatus provided outside the reactor
Implementation Method 4
a catalytic gas-phase oxidation reaction in the case such as producing (meth)acrylic acid or the like from propane, propylene or isobutylene
Implementation Method 5
the catalytic gas-phase oxidation reaction as described above is generally a largely exothermic reaction
Data Source
AI summary
A multi-tubular reaction apparatus, a control system, and a method are provided for controlling temperature change of a heat medium in the reaction apparatus, and quickly adjusting fluctuation in temperature, to thereby properly control a reaction. In particular, the apparatus and system apply to a catalytic gas-phase oxidation reaction such as in producing (meth)acrylic acid or the like. The reaction apparatus includes a multi-tubular reactor having a plurality of reaction tubes in a shell in which a heat medium circulates, and a heat medium cooling apparatus outside the reactor. The reaction apparatus includes a process for primarily cooling the heat medium taken out outside the shell, a process for secondarily cooling a part of the primarily cooled heat medium, and a line for enabling the secondarily cooled heat medium and the primarily cooled heat medium, which is not secondarily cooled, to circulate in the shell.