A New Factory Is To Be Built Where The Use Of Compressed Air Will Have A Major Influence: Energy System Design Assignment, NUI, Ireland

A new factory is to be built where the use of compressed air will have a major influence on the production process. A compressed air system is to be designed to ensure adequate air is supply at the required pressure and quality.

Q1. Select from manufacture data (Kaeser: Free Air Delivery of Unit) a suitable compressor to meet the plant air requirement as outlined in table 1 based on the average demand. Your selection should be for two compressors of equal size, with one compressor acting as a stand-by for peak demand, i.e. when demand exceeds the average demand the second compressor of average demand will operate.

Q2. Based on the compressor selected (average demand) calculate its annual operating cost assuming that the backup compressor does not operate. The average cost of a unit of electricity is 15 c/kWh. The plant operates 8,000 hours per annum. Make the following allowance in your calculation.  1.Compressor Motor Efficiency = 90%

2. Off load power consumption = 25% of total compressor power

3. Load factor = average compressor air demand/compressor capacity

Q3. Select a suitable refrigerant dryer from the Ingersoll-Rand catalog based on the selected compressor rating (m3 /min) for a pressure dew point of 3 deg. c. The dryer is situated in the compressor house where the ambient temperature is 30 deg. c. The compressed air leaves the aftercooler at 40 deg. c where it ten enters the refrigeration dryer.

Q5. Size the diameter of the compressed ring main from the Spirax Sarco datasheet “ Table 12 Pressure Drop in Steel Pipes” based on a maximum pressure loss = 2.5 bar/ meter. Select the nearest larger diameter nominal pipe bore in mm. For pipe, sizing take the compressor cut-out pressure at 0.5 bar greater than the compressor nominal pressure. 3

Q6. Select suitable air filters for the Process Branch Line in table 1 to provide a minimum air quality class “1” for both dirt particles and oil concentration to ISO 8573.1. Used the Filter Type table Ported Range to size the filter pipe connections and filter type. State the type of filter to be installed in terms of DD, PD and QD, and any other type of drying equipment installed. Note: You are required to select the size and number of filters to be installed on the Process Branch Line but only the type of dryer to be installed.

Q7. Draw a schematic layout of the plant on an A4 sheet showing the compressed generation and distribution system piping system include all filters etc. Label all equipment and main plant items.