Heat Recovery Steam Generator (HRSG), Enhanced Oil Recovery Type
Oil field cogeneration projects are identical to refinery projects, as far as the CGTgenerator is concerned. Where they differ is in what they do with the supplementally fired gas turbine exhausts. In the refinery type, (HRSG) normally dry (saturated) and superheated steam are required.
In the oil field, (HRSG), 60% to 80% quality steam is required for injecting into wells at pressures in the 1000 PSIG range to assist in enhanced oil recovery.
Figure 3200-11 is an isometric of a proposed six-parallel-pass, steam generation for enhanced oil recovery. The design for this project is 220,000 pound/hour of 60% quality steam at 775 PSIG, (from 180°F boiler feedwater), by supplementary-firing the gas turbine exhaust to 1394°F. Flow in the preheater is counter-current; flow in the boiler is co-current. Description of finning, size of tubes, number of tubes in height and in depth, and the heat balance equations for both boxes are shown. A sketch on the top summarizes the heat transfer conditions for the preheater and the once-thru boiler.
Figure 3200-12 is an isometric of the rough outline dimensions for a waste heat recovery type behind a General Electric LM-2500 gas turbine for a producing field. This unit is also rated as a 220,000 pound/hour, 775 SIG outlet, once-through, 60% steam generator for enhanced oil recovery. Units of this type have multipass parallel flow. This unit has four passes. There are no steam drums or mud drums. The passes are heated as in any economizer.