How to recycle butyl acetate waste gas? Key points for condensation and recovery configuration of high boiling point ester solvents
Release time: 2026-10-01
View count:
Butyl acetate is a top-consumed ester solvent in the coatings, ink, and leather processing industries. With a boiling point of approximately 126℃, it is slightly higher than ethyl acetate. Its volatilization rate at room temperature is moderate, and the exhaust gas concentration varies significantly depending on the operation method: exhaust gas volume is large and concentration is low in open operations such as spraying and printing, while exhaust gas concentration is high in closed reactions and cleaning processes. The main recovery route is condensation. The high boiling point allows for relaxed temperature requirements, and most of the butyl acetate can be recovered through two stages of water cooling at room temperature. Attention can be placed more on the collection end and condensate reuse.
Butyl acetate is slightly soluble in water, and the condensate can be layered after standing still, which is different from alcohols and ketones, which are miscible solvents. The burden of dehydration for the recovered liquid is light, and the route of layered reuse is feasible. The economic efficiency of recovery is among the better ones among esters.
How to determine the condensation temperature level
The temperature level is calculated based on the dew point corresponding to the intake concentration: The dew point of butyl acetate varies significantly with concentration. For high-volume, low-concentration exhaust gases from spraying operations, the recovery ratio through condensation at room temperature is limited. It is advisable to first concentrate or collect in batches to increase the intake concentration before condensing. For high-concentration exhaust gases in enclosed processes, the recovery rate of two-stage water-cooled condensation is considerable, and the low-temperature stage is only configured when necessary for quality control. Compared to the rapid volatilization of ethyl acetate, butyl acetate condenses more in pipelines. The pipeline slope and low-point drainage settings must be in place, as condensate accumulation can cause intermittent concentration shocks.
The condensation load is calculated based on the measured concentration: the concentration during spraying operations varies with batches and workpieces. The main body of the device is selected based on the median load, with peaks being absorbed by the buffer tank. This calculation should be clarified during the planning stage, considering both investment efficiency and operational stability.
How to collect and reuse in a stratified manner
The focus of the collection end is to separately collect the gas from high-concentration points: the cleaning tank and paint mixing room are partially enclosed, and the high-concentration branch is directly sent to the condensation recovery system; the high-volume exhaust gas from the spray booth is first enriched through a concentration wheel or activated carbon adsorption, and the desorbed gas is then sent to the condensation section. Directly condensing the high-volume low-concentration exhaust gas is not economical. The condensate side follows a stratified reuse route: the condensate enters a stratified tank for standing, separating the ester phase from the aqueous phase. The ester phase is reused after testing for moisture and purity, while the aqueous phase is metered and sent to the sewage system. The property of ester micro-hydrolysis producing acid should not be ignored: if the condensate is stored for a long time, its acidity will increase, affecting both equipment and reuse quality. Quick collection and transfer, as well as regular acidity testing, are fixed actions in condensate management.
The quality threshold for the reuse of recovered liquid is determined based on downstream processes: for paint mixing and cleaning purposes, which have a higher tolerance for water content, a higher proportion of direct reuse after stratification can be adopted; for applications sensitive to purity, an additional distillation purification step should be added, and the recovered liquid should be reused in stages according to its intended use, ensuring a detailed accounting of the recovered liquid.
Configuration key points reference
| project | characteristic | Configuration considerations |
|---|---|---|
| boiling point | About 126℃ | A two-stage water-cooled condensation system is sufficient |
| volatility | Moderate | The condensate in the pipeline is properly drained |
| water-soluble | Slightly soluble and stratifiable | Static reuse of stratified tank |
| Hydrolytic property | Micro-scale acid production | Quickly collect and quickly transfer for acidity detection |
| Low-concentration exhaust gas | High air volume and low concentration | Concentrate first, then condense |
| Reuse classification | Determine depth based on usage | Cleaning and direct use distillation purification |
How to implement operation management
- High-concentration points are collected separately, and high-volume exhaust gas is first concentrated and then condensed;
- The condensation temperature level is calculated based on the measured dew point concentration, ensuring a safety margin for the control section;
- Ensure the pipeline slope and low point drainage are in place to prevent condensate accumulation;
- Condensate is reused after stratification, and the water purity of the ester phase is tested batch by batch;
- Regularly test the acidity of condensate, and ensure quick collection and transfer without prolonged storage;
- The recovery liquid is graded according to its purpose, and the recovery amount is compared with the input amount on a monthly basis.
Frequently Asked Questions
Can the butyl acetate recovery liquid be directly reused in paint mixing?
After stratified testing, most of the ester phase that meets the standards for moisture and purity can be directly reused for paint mixing and cleaning; for processes sensitive to purity, an additional level of distillation purification is required, and the degree of reuse should be determined based on the intended use.
What is the difference in the recovery configuration with ethyl acetate?
Butyl acetate has a higher boiling point, allowing for a more relaxed condensation temperature range; the condensate can be layered, reducing the burden of dehydration. Ethyl acetate volatilizes quickly and hydrolyzes even faster, necessitating closer monitoring of acidity management. The main differences in their configurations lie in the temperature range and the condensate side.
Why is the benefit of directly condensing spraying exhaust gas low?
The high air volume dilutes the concentration, leading to a decrease in dew point, and the condensation ratio at the same temperature level drops significantly. By concentrating first to increase the inlet air concentration and then condensing, the cost can be justified. Most of the investment in the concentration process can be recovered from the recycling benefits.
This article is compiled by Luoyang Wohong Petrochemical Equipment Co., Ltd., which provides design, manufacturing, and operation and maintenance services for condensation recovery, membrane separation recovery, and complete solvent recovery equipment to chemical and pharmaceutical enterprises. If you need process evaluation or scheme configuration, please feel free to contact us for discussion.
