Energy Saving And Efficiency Improvement Of Air Separation Units Have Become An Industry Trend

Industry Background

As core utilities in chemical parks, air separation units (ASUs) provide high-purity oxygen and nitrogen for refining and coal chemical projects. These units are becoming increasingly large-scale and intelligent. With the deepening of China's "dual control" and carbon emissions control policies, energy conservation not only reduces operating costs but also offers preferential policies. Energy conservation and efficiency improvement in ASUs have become key to competitive advantage in the industry. NEWTEK 's optimization practices for its 33,000 Nm³/h ASU (supporting ethylene oxide/ethylene glycol projects) provide a replicable technical solution for similar units.

Plant Overview

This unit utilizes a liquid oxygen internal compression process. Its core configuration includes a vertical radial flow molecular sieve, a multi-layer bath-type main condenser/evaporator (primary cooling), an electrically driven air compressor/booster, and a structured packing distillation column. It is also equipped with a full distillation argon production system and an oxygen, nitrogen, and argon liquid storage and filling system. The process flow is shown in the following diagram:

Simplified Flowchart of a 33,000 Nm³/h Air Separation Unit

●Core Parameters
Oxygen Production Capacity: 33,000 Nm³/h
Purpose: Supplying ethylene oxide/ethylene glycol plants, and also supplying oxygen and nitrogen pipeline gas to surrounding customers
●Key Configurations
Process: Liquid oxygen internal compression
Core Components: Vertical radial flow molecular sieve, multi-layer bath-type primary cooler, electric-driven air compressor/booster, structured packing distillation column
Energy-saving Design: Generator at the braking end of the gas/liquid expander to recover mechanical energy
●Streamlined Process
Feed air → Self-cleaning filter → Compression by air compressor → Cooling by pre-cooling system
Compressed air → Purification system for water/carbon dioxide removal → Main heat exchanger → Booster
Gas → Main heat exchanger → Expander → Lower column, distilled in upper/lower column
Nitrogen, liquid nitrogen, and liquid oxygen are obtained in the middle of the lower column, the top of the upper column, and the upper section of the primary cooler, respectively. Liquid oxygen at the bottom of the primary cooler → Pressurization → Reheating → High-pressure oxygen product
 

Optimization Measures

NEWTEK achieved economical operation of the unit through four major measures: load reduction, tower pressure adjustment, argon yield improvement, and liquid loss reduction. Specific results are shown in the table below:
 

Industry Value: Replicable Technology Promotes Green Production

This optimization validates the effectiveness of the "load reduction, parameter adjustment, and loss control" approach-while ensuring stable product quality, through refined operation and control optimization, annual profit increases exceeding 2 million Yuan have been achieved. This solution is particularly suitable for large-scale air separation units, and has direct reference significance for the energy-saving transformation of similar equipment in the refining and coal chemical industries, providing a practical example for the green and low-carbon development of the industry.