Direct Cooling Fluid Injection in Isocyanate Separation
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Solution Overview
Problem
Existing processes for producing organic isocyanates in the gas phase face challenges such as deposit formation in wash columns and condensers, leading to increased maintenance costs and unwanted condensation of phosgene, which affects the efficiency of the workup process.
Innovation Solution
A cleaning apparatus with an addition unit for direct introduction of a cooling fluid into the gas conduit to facilitate partial condensation and absorption of the gas stream, ensuring that phosgene remains predominantly in the gas phase, thereby minimizing deposits and condensation, and optimizing the prepurification of the gaseous product stream without affecting the volume flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a condenser is installed to reduce volume flow in the wash column, then the size of the wash column can be reduced, but deposits form in the condenser requiring cleaning and shutdown
Solution Approach 1:
The patent extracts the condensation function from a separate condenser device and integrates it directly into the wash column through cooling fluid addition units. This eliminates the deposits problem in external condensers while maintaining volume flow reduction benefits, allowing continuous operation without shutdowns for cleaning.
Solution Approach 2:
The patent merges the condensation function with the wash column by introducing cooling fluid directly into the gas stream within the wash column. This combination allows the wash column to perform both washing and condensation functions simultaneously, preventing deposit formation in separate condenser equipment.
2Volume of moving object
If cooling fluid is introduced to condense the gas stream, then volume flow is reduced, but phosgene may condense along with the isocyanate
Solution Approach 1:
The patent applies local quality by introducing cooling fluid at specific locations and in controlled amounts within the wash column. The cooling is localized to achieve partial condensation of isocyanate while maintaining conditions that prevent phosgene condensation, thus reducing volume flow without losing phosgene.
Solution Approach 2:
The patent changes physical parameters (temperature, cooling fluid amount, introduction location) to achieve selective condensation. By carefully controlling these parameters, the system condenses isocyanate while keeping phosgene in the gas phase, thereby reducing volume flow without phosgene loss.
3Productivity
If the wash column is designed for high volume flow, then continuous operation is maintained, but the column size and cost increase
Solution Approach 1:
The patent performs preliminary condensation action by introducing cooling fluid upstream in the wash column. This reduces the volume flow before the main washing section, allowing a smaller wash column design while maintaining continuous operation capability. The cooling action prepares the gas stream for more efficient processing.
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 solution significantly extends the service life of the apparatus by reducing deposit formation and maintaining phosgene in the gas phase, enhancing the efficiency of the separation process and reducing maintenance needs, while maintaining continuous operation.
Implementation Method 1
at least one addition unit (11) for direct introduction of at least one cooling fluid for an at least partial condensation and/or absorption of the gas stream conductable through the first gas conduit (9) is assigned to the first gas conduit (9)
Implementation Method 2
at least one addition unit (11) for direct introduction of at least one cooling fluid for an at least partial condensation and/or absorption of the gas stream conductable through the first gas conduit (9) is assigned to the first gas conduit (9)
Data Source
AI summary
Provided is a process for separating an organic isocyanate prepared by reacting an organic amine with a stoichiometric excess of phosgene in the gas phase from the gaseous crude product obtained in the reaction, the process comprising the steps of (i) at least partially condensing the crude product stream containing at least the isocyanate, hydrogen chloride and unconverted phosgene by contacting with at least one liquid stream containing at least one quench liquid in a first separation apparatus to obtain a liquid stream containing at least some of the quench liquid and some of the isocyanate and a gas stream containing at least hydrogen chloride, evaporated quench liquid and phosgene, (ii) discharging the liquid stream obtained in step (i) via a first liquid outlet and of the gas stream obtained in (i) via a first gas conduit and (iii) at least partially condensing and/or absorbing the gas stream discharged in step (ii) through the first gas conduit, wherein that the at least partial condensation and/or absorption is effected in step (iii) by direct introduction of at least one cooling fluid, wherein the cooling fluid is introduced directly into the first gas conduit via at least one addition unit assigned to the first gas conduit.