Ammonia Vent Gas Scrubbing With Acidic Wash Water Recirculation
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Solution Overview
Problem
Existing ammonia vent gas treatment systems in ammonia-propelled and dual-fuel engine vessels face challenges with ammonia leakage due to evaporation from residual ammonia in storage tanks and inefficient recovery and reuse of ammonia, leading to concentrations exceeding allowable levels.
Innovation Solution
An ammonia vent gas treatment system that includes a vent gas treatment facility with a knockout drum and absorption tank, using acidic water as wash water, and a gas pipe to return ammonia gas to the facility, along with a gas detector to control ammonia concentration through water or air adjustment based on fuel supply valve state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If fresh water is used in the ammonia vent gas treatment system, then ammonia can be absorbed through water, but ammonia re-evaporates from the water causing hazardous concentrations to be discharged externally and the system becomes large in size
Solution Approach 1:
The patent changes the chemical parameter of the wash water from neutral (fresh water) to acidic by introducing CO2 dissolution. This parameter change prevents ammonia re-evaporation by converting ammonia to ammonium ions through acidification, solving the hazardous discharge problem without requiring larger facility size
Solution Approach 2:
The patent converts the harmful effect of CO2 (acidic gas) into a beneficial function by using it to acidify the wash water. The CO2 that would normally be considered a harmful emission becomes the means to prevent ammonia re-evaporation, simultaneously treating two harmful gases
2Loss of substance
If ammonia water is recovered through the vent gas treatment facility, then ammonia discharge is reduced, but residual ammonia on tank inner walls evaporates causing ammonia gas exceeding allowable levels
Solution Approach 1:
The patent applies preliminary acidification to the ammonia water before storage. By converting ammonia to ammonium ions in advance through CO2 dissolution, the system prevents subsequent re-evaporation from tank walls, eliminating the need for additional treatment after storage
Solution Approach 2:
The patent introduces CO2 as an intermediary substance that mediates between the ammonia water and the storage tank. The CO2 dissolves in the water to form carbonic acid, which then reacts with ammonia to form ammonium carbonate, preventing direct contact between ammonia and tank walls that would cause evaporation
3Volume of stationary object
If the vent gas treatment facility size is reduced for space efficiency, then space is saved, but ammonia recovery and treatment efficiency may be compromised
Solution Approach 1:
The patent changes the chemical parameter of the wash water to acidic, which dramatically improves ammonia absorption efficiency. This parameter change allows smaller facility size to achieve the same or better recovery efficiency, as acidic water has higher capacity for ammonia removal per unit volume
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 maximizes ammonia recovery and reuse, effectively reduces hazardous ammonia concentrations by re-evaporation, and efficiently manages ammonia levels, potentially reducing the size of the treatment facility.
Implementation Method 1
ammonia water discharged from a consumer of fuel... use acidic water discharged from a consumer of fuel as wash water for a vent gas treatment facility... The acidic water reacts with ammonia to form ammonium ions, preventing re-evaporation
Implementation Method 2
ammonia evaporates from residual ammonia remaining on the inner wall of a tank storing the recovered ammonia water... ammonia gas generated in the tank
Data Source
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AI summary
The present disclosure relates to an ammonia vent gas treatment system for an ammonia-propelled vessel. The vent gas treatment system includes: a vent gas treatment facility configured to recover and treat ammonia discharged from a consumer of ammonia fuel or from an intermediate component that supplies ammonia fuel to the consumer; a wastewater tank for storing ammonia water discharged from the vent gas treatment facility; and a gas pipe for returning ammonia gas generated in the tank to the vent gas treatment facility, thereby efficiently addressing not only the discharge of ammonia water but also the problem of ammonia gas in the tank storing the ammonia water