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Air vs. Steam Atomization Part 5 – Compressor Capacity
Posted on August 17th, 2017 by David W. Spitzer, P.E. in Chemical Manufacturing Excellence
Previous posts discussed the incineration and atomization processes. The fact that the compressor currently unloads indicates that there is additional air compressor capacity that is currently not being used. The question is whether there is sufficient compressor capacity to supply the plant load plus the proposed air atomization. If not, a new compressor may be needed.
In addition, operating the air compressor below half speed will damage the compressor. Therefore, the total load (plant plus atomization) must also be greater than half of the compressor capacity. This constraint needs to be considered because observation revealed that the compressor handled the existing plant air load by loading for 30 seconds and unloading for 60 seconds. Therefore, approximately one-third of the compressor capacity was being utilized and approximately two-thirds of the compressor capacity was available for air atomization.
The amount of atomization gas required is approximately one-third to one-half of the liquid waste flow on a mass basis. Atomizing approximately 210 lb/min of liquid waste would require approximately 70 lb/min of atomization gas, which is 4200 lb/hr of steam (70 lb/min * 60 min/hr) or 933 cfm (70 lb/min / 0.075 lb/ft3) of atomizing air. The latter represents almost one-half of the compressor capacity (2000 cfm) so it is clear that adding this load to a one-third loaded compressor would cause the compressor to operate continuously above half load and hence, over half speed. Ideally, the compressor would operate between (say) 65 and 85 percent capacity at all times to avoid issues associated with unloading and insufficient capacity. Note that operating the compressor fully loaded at these speeds will increase electrical energy consumption in order to produce plant air plus the additional atomizing air.
See previous posts:
- Air vs. Steam Atomization Part 1 – Sustainability
- Air vs. Steam Atomization Part 2 – The Incineration Process
- Air vs. Steam Atomization Part 3 – The Atomization Process
- Air vs. Steam Atomization Part 4 – Atomization Reliability
All opinions shared in this post are the author’s own.
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David W. Spitzer, P.E.
Principal at Spitzer and Boyes, LLC
- Air vs. Steam Atomization Part 11 – Project Justification
- Air vs. Steam Atomization Part 10 – Economics (Capital Costs)
- Air vs. Steam Atomization Part 9 – Economics (Atomizing Air vs. Atomizing Steam Production)
- Air vs. Steam Atomization Part 8 – Economics (Plant Air Production)
- Air vs. Steam Atomization Part 7 – Economics (Stack Losses)