Document Code: 1 (5) Project : MULTI FUEL CFB BOILER SIMULATOR Author: Approved: Language: JJA Document title: SYSTEM DESCRIPTION MAIN CONDENSATE PUMPING Submitted for: Customer reference: Other information:
Document Code: 2 (5) TABLE OF CONTENTS 1 GENERAL... 3 2 DESIGN DATA... 4 3 EQUIPMENT DATA... 4 4 AUTOMATION AND INSTRUMENTATION... 4 4.1 Condenser level control... 4 5 OPERATION... 5 5.1 Start-up... 5 5.2 Normal operation... 5 5.3 Operating disturbances... 5 6 CONNECTED SYSTEMS... 5
Document Code: 3 (5) 1 GENERAL Function of the main condensate pumping system is to pump condensate from the condenser through the LP preheaters to feed water tank. It also supplies spray water to the LP bypass station (S1 LBB20 AA201) to be adjusted with control valve (S1 LCE10 AA201) and cooling/seal water for Turbine Island users. System is shown on P&I diagram S1LC -MFB1001. Condenser itself (also the gland steam condenser) is in Turbine Island scope of supply. The system is equipped with 2x100 % main condensate pumps (S1 LCB10/20 AP101). During normal operation one pump is running with constant rotation speed and the level in the condenser is regulated with control valve S1 LCA30 AA201. From the condenser water is pumped through LP preheaters (3 pcs.) to feed water tank. Flows entering the condenser are: Turbine exhaust Cold reheat Feed water HP- & LP preheaters and turbine drainages LP 1 preheater condensate Demineralised make-up water (according to feed water tank level) Steam from LP preheater by-pass station (start-up, turbine trip, shut-down) After the pumps there is a flow measurement and during the start-up / other boiler part load situation adequate flow for the pumps is secured with minimum flow valve. From the hot reheat piping there is a LP bypass station to condenser. Bypass station is used during start-up / shutdown and in case of steam turbine trip. Spray water for the LP bypass is taken from the main condensate pumps. In steam turbine trip bypass station in controlling hot reheat steam pressure and large amount of condensate is taken quickly to spray water purposes (hydraulic valves). In order to keep the main condensate pumps in right operation range, in turbine trip second main condensate pump is started automatically. Both main condensate pumps are running always when LP-bypass is at maximum. From the main condensate line water is taken also to steam turbine cooling during start-up- / shutdown and sealing waters to valve / water seals. During normal operation these connections are closed.
Document Code: 4 (5) 2 DESIGN DATA System design is based on situation where boiler load is at 100 % (ambient air +9 C, cooling water +12 C) and make-up up water flow is calculated based on 3 % blow down. When LPbypass is at maximum flow (turbine trip), both main condensate pumps are running. 3 EQUIPMENT DATA Main condensate pumps S1 LCB10/20 AP101 Function of the main condensate pumps is to pump condensate arising to condenser through the LP preheaters to feed water tank. Pumps are located in the pump pit underneath condenser. Number of units 2x 100 % Type KSB / MTC-A 150/04 12.1 Flow rate 80,1 kg/s Head 159 m Pumping temperature 23 C Motor power 200 kw 4 AUTOMATION AND INSTRUMENTATION 4.1 Condenser level control Main condensate pumps are running with constant speed and the level is controlled with valve S1LCA30 AA201. Low-level protection for the main condensate pumps is done by level measurement interlock and low-level switch. To main condensate pumping is also related the minimum flow control. During start-up and other low load situations minimum flow for the pumps and for the gland steam condenser is ensured with control loop FIC S1 LCA30 CF201.
Document Code: 5 (5) 5 OPERATION 5.1 Start-up Turbine and condenser start-up (vacuum pumps etc.) in detail is in Turbine Manufacturers scope of supply. Before the main condensate pumping system can be started, condenser and suction lines to pumps are filled with water. One main condensate pump is started against closed discharge valve (motorised), control valve S1 LCA30 AA201 is closed. Motorised valve S1 LCA10 AA101 (or S1 LCA20 AA101) is opened partly. When pressure S1 LCA30 CP201 after the pump starts to increase, also the minimum flow valve is opened partly. Finally motorised valve is opened fully and minimum flow control S1 LCA30 AA201/-CF201 is set to Auto mode. Piping system from the control valve S1 LCA30 AA201 to feed water tank is filled by opening control valve partly. In initial start-up lines are vented manually. When the system is filled with water, condenser level control LICSA S1MAG10 CL201 is set to Auto mode. In hot/ warm start-up (lines / heat exchangers full of water) start-up procedure can be handled from the control room. Main condensate pump is started against closed MOV (S1 LCA10/20 AA101) and the valve is opened. Both minimum flow control and condenser level control are set to Auto mode. 5.2 Normal operation One main condensate pump is running while the other is stand-by. All the condensates from the condenser are pumped to feed water tank and connections to LP bypass spray and to turbine cooling are closed. 5.3 Operating disturbances. Failure of the running main condensate pump Second pump will automatically start. Turbine trip Second main condensate pump starts and LP bypass station is opened automatically. 6 CONNECTED SYSTEMS LP preheating system HP steam system Condenser Feed water system HP preheaters Make up water system S1 LCC -MFB1001 S1 LB -MFB1001 S1 LB -BFB2506 S1 LA -MFB1001 S1 LAD -MFB1001 S1 GHC -MFB1001