Devise a preliminary control scheme for the sections of the nitric acid plant described in Chapter 4, flow-sheet Figure 4.2, which are listed below. Make a practice HAZOP study of each section and revise your preliminary control scheme.
1. Waste heat boiler (WHB)
2. Condenser
3. Absorption column

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Flows kg/h Pressures nominal 1A 2 2A Line no. 1 Stream Ammonia Ammonia Filtered Oxidizer Component Feed Vapour Air Air 731.0 731.0 NH3 0₂ N₂ NO NO₂ HNO3 H₂O Total Press bar Temp. °C 731.0 8 15 731.0 8 20 731.0 3036.9 2628.2 2628.2 9990.8 8644.7 8644.7 3 4 5 6 7 8 9 10 11 12 13 Oxidizer Oxidizer W.H.B. Condenser Condenser Secondary Absorber Tail(2) Water Absorber Product C & R Construction Inc Feed Outlet Outlet Gas Acid Air Feed Gas Feed Acid Acid 1 15 8 230 Nil 1161.0 Trace 13,027.7 11,272.9 12,003.9 12,003.9 12,003.9 Nil 935.7 (935.7)(1) 275.2 8668.8 8668.8 1238.4 (1238.4)(1) 202.5 Trace 8668.8 (?)(1) Nil 1161.0 10,143.1 8 204 - 8 907 8 234 8 40 Trace Trace 967.2 29.4 1860.7 1 40 408.7 1346.1 850.6 1010.1 1754.8 8 40 - 683.9 371.5 10,014.7 10,014.7 202.5 21.9 967.2 - 8 40 - 1 25 Trace Trace Trace (Trace) (¹) 29.4 26.3 1376.9 11,897.7 10,434.4 1376.9 2840.0 - - 8 - 25 1 40 - Trace Trace Trace Trace 1704.0 1136.0 4700.6 1 43 Nitric acid 60% %100,000 t/y Client BOP Chemicals SLIGO Trace Sheet no. 9316 2554.6 2146.0 Dwg by Date Checked 25/7/1980