Sulfuric Acid Plant Layout Heat Recovery

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Solution Overview

Problem

Conventional sulfuric acid production processes are thermally inefficient and require extensive heat exchange areas, leading to high operating costs and complexity, particularly in dual condensation layouts where reheating and cooling processes are inefficient.

Innovation Solution

A simplified sulfuric acid plant layout with improved heat recovery and reduced heat exchange area, featuring a modified first condensation step and reheating process, where the gas from the first condenser is directly mixed with recycled hot process gas without intermediate heat exchange, and enhanced mixing devices to prevent corrosive acid condensation, utilizing catalytically active materials like alkali-vanadium or platinum for efficient SO2 to SO3 conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional dual condensation layout with intermediate cooling and reheating is used, then SO2 conversion efficiency is improved, but heat exchange area and device complexity increase

Engineering Contradiction:

ImproveSO2 conversion efficiencyVSAvoidheat exchange area

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the cooling and reheating operations into a single heat exchange step by directly mixing the cooled process gas with hot regenerated sulfuric acid vapor. This eliminates the need for separate cooling and reheating heat exchangers, reducing the total heat exchange area while maintaining the thermal conditions necessary for high SO2 conversion efficiency in the subsequent catalytic oxidation step.

Inventive Principle:

Principle #5Merging (Combining)

2Manufacturing precision

If extensive heat exchange area is used for cooling and reheating, then process control precision is improved, but operating cost increases

Engineering Contradiction:

Improveprocess control precisionVSAvoidoperating cost

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent converts the waste heat from the regenerated sulfuric acid vapor into a useful heating source by directly mixing it with the cooled process gas. This eliminates energy losses associated with separate cooling and reheating operations, as the heat that would otherwise be wasted is now utilized to reheat the gas to the required temperature for catalytic oxidation, thereby reducing operating costs while maintaining process control precision.

Inventive Principle:

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

3Reliability

If intermediate cooling step is added, then SO2 conversion efficiency is improved, but energy loss increases

Engineering Contradiction:

ImproveSO2 conversion efficiencyVSAvoidenergy loss

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent eliminates energy loss by directly utilizing the hot regenerated sulfuric acid vapor to reheat the cooled process gas in a single mixing operation. This converts what would otherwise be waste heat into a useful thermal energy source, maintaining the temperature conditions necessary for high SO2 conversion efficiency while minimizing energy losses throughout the process.

Inventive Principle:

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

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

This layout results in a more energy-efficient and cost-effective sulfuric acid production process with reduced equipment needs, improved thermal integration, and robust operation, achieving higher SO2 conversion efficiencies while minimizing corrosion risks and energy losses.

Implementation Method 1

catalytic oxidation of SO2 to SO3

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

oxidation of SO2 to SO3

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

condensation of H2SO4 to withdraw the desired sulfuric acid product

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 4

combining said partially desulfurized gas with a recycled hot intermediate process gas

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 5

enhanced mixing devices to prevent corrosive acid condensation

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS10829376B2Process for production of sulfuric acid

Publication Date: 2020.11.10 HALDOR TOPSOE AS

AI summary

A process plant for production of sulfuric acid from a process gas comprising SO2, including a process gas inlet, a first SO2 converter having an inlet and an outlet, a first condenser having a gas inlet, a gas outlet and a liquid outlet, a gas mixing device having a first inlet, a second inlet and an outlet, a process gas heater having an inlet and an outlet, a second SO2 converter having an inlet and an outlet, a second condenser having a gas inlet, a gas outlet and a liquid outlet, one or more means for cooling and storage of sulfuric acid and a purified process gas outlet.