Boiling Water Reactor By-Pass Insert Cooling

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Solution Overview

Problem

Boiling water reactors face challenges in managing high temperatures of the upper tube sheet during exothermic reactions, particularly when catalyst is loaded above the tube sheet, which can lead to damage and catalyst shrinkage issues.

Innovation Solution

A reactant by-pass insert is mounted at the top of the upper tube sheet to divert a portion of the reactant gas around the catalyst layer, creating a cooling effect that prevents excessive heating of the tube sheet and allows for additional catalyst loading above the sheet, compensating for catalyst shrinkage by sinking into the reaction tubes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If catalyst is loaded above the upper tube sheet to increase reactor capacity, then the reactor productivity is improved, but the temperature of the upper tube sheet becomes too high causing damage risk

Engineering Contradiction:

Improvereactor capacityVSAvoidupper tube sheet temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The reactant gas flow is segmented into two paths: one path flows through the catalyst layer above the tube sheet for reaction, while another path bypasses the catalyst and flows directly over the upper tube sheet to provide cooling. This flow segmentation allows simultaneous catalyst operation and tube sheet temperature control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A portion of the reactant gas acts as a cooling medium (intermediary) that absorbs heat from the upper tube sheet. This cooling gas stream mediates between the exothermic reaction zone and the tube sheet, preventing excessive temperature rise without requiring additional cooling system complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If catalyst is loaded above the upper tube sheet, then the reactor capacity is increased, but the reliability of the tube sheet deteriorates due to high temperature damage risk

Engineering Contradiction:

Improvereactor capacityVSAvoidtube sheet reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The cooling reactant gas is directed to flow over the upper tube sheet before the reaction zone, creating a protective cooling effect in advance. This preliminary cooling action prevents the tube sheet from reaching damaging temperatures before the exothermic reaction fully occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The reactant gas, which would normally be heated by the exothermic reaction, is instead utilized as a cooling medium by directing it to flow over the upper tube sheet. The heat absorption that would occur during reaction is converted into a beneficial cooling effect for the tube sheet.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Temperature

If cooling medium flow is increased to cool the upper tube sheet, then the tube sheet temperature is reduced, but the reactor productivity decreases due to reduced reactant flow through catalyst

Engineering Contradiction:

Improveupper tube sheet temperatureVSAvoidreactor capacity

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

Only a portion (partial action) of the total reactant gas flow is diverted to cool the upper tube sheet, while the majority continues to flow through the catalyst layer for the intended chemical reaction. This partial cooling approach maintains adequate reaction throughput while providing necessary temperature control.

Inventive Principle:

Principle #16Partial or excessive action

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 by-pass insert effectively cools the upper tube sheet, preventing damage from high temperatures while maintaining reactor capacity and allowing for increased catalyst loading without compromising performance due to controlled reactant flow and pressure adjustments.

Implementation Method 1

The cooling medium is arranged to flow between the cooling medium inlet and the cooling medium outlet, around the reaction tubes, so that the reaction tubes are in thermal contact with the cooling medium

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The reactor shell volume is dimensioned so as to allow boiling of a liquid phase of the cooling medium within the reactor shell volume

Methodology Applied

Scientific EffectBoiling: Boiling

Implementation Method 3

a mixture of steam and water may pass through at least one cooling medium outlet to an external steam drum for separation of the liquid and the gas phase

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 4

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS10525428B2Boiling water reactor

Publication Date: 2020.01.07 HALDOR TOPSOE AS

AI summary

The invention relates to a boiling water reactor for an exothermal reaction. The reactor comprises reactant by-pass inserts arranged on top of the upper tube sheet to provide for a catalyst layer on top of the upper tube sheet and also a cooling stream of reactant by-passing the upper layer of catalyst and cooling the upper tube sheet from the temperature rise due to the exothermal reaction taking place in the upper layer of catalyst.