Gas Stream Scrubbing With Evaporative Cooling Water Recovery
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Solution Overview
Problem
Existing methods for treating high-temperature gas streams from thermal power plants, particularly those containing CO2, NOx, SOx, and suspended matter, are inefficient in reducing corrosion risks and energy consumption, and do not effectively utilize the liquid byproducts from scrubbing processes for continuous cooling.
Innovation Solution
A method and apparatus that utilize the liquid byproducts from scrubbing to cool air and water through evaporation or indirect heat exchange, optimizing energy use by storing and regulating liquid release based on ambient temperature, and integrating filtration and demineralization to manage impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the liquid from the scrubbing tower is used to cool air and water through evaporation, then energy consumption in gas compression is reduced, but the liquid contains impurities (suspended matter, dissolved minerals, acid gases) that may cause corrosion or operational issues
Solution Approach 1:
The patent introduces an intermediary substance (inorganic salt such as calcium chloride, calcium nitrate, or ammonium nitrate) that is added to the scrubbing liquid before it is used for cooling. This intermediary serves multiple functions: it prevents corrosion by creating a protective environment, manages impurities by controlling freezing points and solubility, and enables the liquid to be safely reused in the cooling circuit without causing damage to equipment or reducing compression efficiency.
Solution Approach 2:
The patent changes the chemical and physical parameters of the cooling liquid by adding inorganic salts, which alters the liquid's properties including freezing point, boiling point, solubility characteristics, and corrosion resistance. These parameter changes transform the impure scrubbing liquid into a suitable cooling medium that can withstand the operational conditions while maintaining energy efficiency in gas compression.
2Loss of substance
If the scrubbing liquid is reused for cooling without treatment, then water consumption is reduced, but suspended matter and dissolved minerals accumulate and reduce cooling efficiency
Solution Approach 1:
The addition of inorganic salts fundamentally changes the thermal and chemical parameters of the cooling liquid, allowing it to maintain effective cooling performance even after multiple reuse cycles. The salt concentration is carefully controlled to optimize both corrosion protection and cooling efficiency, enabling continuous operation without water replacement.
Solution Approach 2:
The patent establishes a continuous cooling system where the scrubbing liquid, now modified with inorganic salts, can be circulated and reused indefinitely without losing its cooling capability. The inorganic salt additive prevents the degradation that would normally occur from impurity accumulation, ensuring continuous useful action in the cooling process and eliminating the need for periodic water replacement or system shutdowns.
3Temperature
If ambient temperature is high, then evaporative cooling of the scrubbing liquid is more effective, but the liquid may contain dissolved acid gases (NOx, SOx) that become more problematic at higher temperatures
Solution Approach 1:
The patent converts the harmful dissolved acid gases into a beneficial system by adding inorganic salts that create a chemical environment where these gases are further stabilized or precipitated. The inorganic salt additive transforms the potentially harmful acidic liquid into a controlled cooling medium where acid gases are managed through controlled chemistry, and the evaporation process actually helps concentrate and manage these components safely.
Solution Approach 2:
By adding inorganic salts, the patent changes the chemical parameters of the liquid to increase its buffer capacity and pH stability, which prevents the dissolved acid gases from causing corrosion or harmful effects even when temperatures rise and evaporation is more active. The modified liquid composition maintains stability across a wider temperature range.
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
Reduces energy consumption in gas compression and enhances continuous cooling efficiency by leveraging scrubbing byproducts, while minimizing corrosion and impurity risks.
Implementation Method 1
The liquid is optionally treated to reduce the amount of suspended matter and dissolved minerals and is then evaporated in an air stream at the inlet of the air coolers of a cooling water circuit in order to lower the air temperature
Implementation Method 2
the cooled air flow is used to cool a water flow by indirect or direct heat exchange forming a cooled water flow
Data Source
Figure 1
AI summary
In a gas stream washing process, liquid (7) from the scrubbing tower (K) is vaporized (E1) to cool ambient air (19) which is then used to cool water (25) producing cooling water (27) for use upstream or downstream of the washing process.