R016600x

Supplement I

1.1.11 Make-up Tank A make-up tank is required to collect low pressure condensate and fresh softened make-up water. Steam is introduced to the make-up tank through a temperature control valve. The make-up tank temperature should be maintained between 190°–200° F. The make-up tank must be sized for the total boiler horsepower rating of the system. The make-up tank must also have sufficient elevation to provide the required NPSH of the make-up. 1.1.12 SCR Transfer Pump An SCR transfer pump is required to transfer water from the make-up tank to the SCR (regenerative turbine type preferred). This pump must have a capacity that is at least equal to the total boiler feedwater pump capacity. The make-up pump must have a discharge head not less than 25 percent higher than the maximum receiver operating pressure. The discharge from this pump must enter the SCR below the minimum water level.

NOTE A check-valve must be installed in the make up pump discharge line as close to the SCR as possible. This will prevent exposing the pump seal to excessive fluid temperatures.

1.1.13 Chemical Treatment Feedwater Chemical Treatment is injected into the SCR below the water level. Feedwater treatment Chemicals are also be injected into the make-up tank to help protect the make up against corrosion. Both of these chemical injection lines must have a check-valve installed to pre- vent back feeding into the chemical pumps. Chemical pump output pressure must be greater than SCR pressure. 1.1.14 Hook-up The feedwater line between the SCR and the generator feedwater water pump must have an inside diameter of 2 times that of the SCR discharge connection and the feedwater pump inlet connection. The pipe run to Clayton’s positive displacement (PD) feedwater pump must be as short as possible (absolute minimum), and the elbows and restrictions must be kept at a minimum. A flex section (2 feet minimum) must be installed on the feedwater pump inlet. A port for a ther- mometer and a feedwater sampling port must be as close to the feedwater pump inlet as possible. The pipe run from the SCR to Clayton’s PD feedwater pump must be held as level as pos- sible. No u-shaped pipe sections (either up or down) are allowed. This pipe run must be a contin- uous 2°–3° rise from Clayton’s PD feedwater pump back up to the SCR discharge connection. All reducers must be eccentric with the flat side up.

SI-3

07/10/2015

Supplmt01_SCR_c.fm