Condensate Management

Condensate Return Let’s take a look at a savings analysis... Hotter boiler feed water temperatures Minimizes the amount of chemicals required to treat boiler feed water Eliminates environmental concerns Minimizes water usage which is critical in some areas Condensate is a tangible item which can be measured in the form of a savings analysis Effective return can lower overall costs which can impact profitability Let’s take a look at a savings analysis...

Methods of condensate return Electric Centrifugal Pumps Duplex 4300 series installed at a brewery

Electric Condensate Pumps (Centrifugal) Control Panel w/starters Condensate Inlet Overflow to drain Pump and motor assembly Float switch or alternator Receiver: Non-pressurized Suction isolation valve

Nema 1 Float Switch for simplex (one pump) packages

Nema 1 Mechanical Alternator for duplex (two pumps) packages

Nema 12 Control Panel

Installation Accessories

Advantages Excellent for returning cooler condensate Standard models 200°F or less 210° floor mounted units available 212° elevated units available Inexpensive for initial purchase Low inlet height applications Can operate against high back pressures without dramatically increasing foot print of package Most understood method of condensate return

Disadvantages Long term repetitive maintenance costs Leaking seals High temp condensate from blow through traps or leaks in system Impeller wear – Cavitation Condensate temperature exceeds NPSH design of pump Corrosion on electrical components Requires two trades for installation and repair Safety for pit areas (flooding) Must be vented to atmosphere Units sized 3:1 to allow condensate to cool

Disadvantages

Mechanical Pumps

Pump Trap Operation

Pump Trap Operation: Filling Step 1. During filling, the steam or air inlet and check valve on pumping trap outlet are closed. The vent and check valve on the inlet are open. Steam/Air In - Closed Steam/Air Out - Open Open Check Valve Closed Check Valve

Pump Trap Operation: Begin Pumping Steam/Air In - Open Steam/Air Out - Closed Check Valve Closed Open Check Valve Step 2. Float Rises with level of condensate until it passes trip point, and then snap action reverses the positions shown in step one.

Pump Trap Operation: End Pumping Step 3. Float is lowered as level of condensate falls until snap action again reverses positions. Steam/Air - In Vent Closed Closed Check Valve Open Check Valve

Pump Trap Operation: Repeat Filling Step 4. Steam or air inlet and trap outlet are again closed while vent and condensate inlet are open. Cycle begins anew. Steam/Air Out - Open Steam/Air In - Closed Open Check Valve Closed Check Valve

Mechanical vs. Electrical No seals, motors or impellers Eliminates repetitive maintenance Low maintenance Few moving parts – advanced mechanism design Sized for actual condensate load: No need to apply 3:1 safety factor Hot condensate is no problem Can be used in closed loop applications Conserve flash steam (BTU’S)

Stall Heat Exchanger Stall The point at which there is no differential across the trap orifice and condensate starts to back up in to the system

Big Problem

“Stalled” Heat Exchanger Steam Condensate

Effects of “Stall” Inadequate condensate drainage Water hammer Frozen coils or coil leaks Corrosion due to Carbonic Acid formation Poor temperature control of product (water, air etc) Control valve hunting (system cycling) Reduction of heat transfer capacity

Factors Contributing to Stall Oversized equipment Conservative fouling factors Excessive safety factors Large operating ranges Back pressure at steam trap discharge Changes in system parameters

Finding “Stall” Modulating Steam Control Where does Stall occur? Air heating coils Shell & tube heat exchangers Plate & frame heat exchangers Reboilers Kettles Any type of heat transfer equipment that has Modulating Steam Control

Mechanical Pump Applications

Closed-Loop Systems

Big Problem

Closed-loop Solution

Solution: Closed Loop CO2 evaporator 32 32

Closed-loop Solution

Considerations for closed-loop systems Receiver sizing Typically smaller receiver to handle condensate load only Vent sizing on receiver Vent line is equalized to receiver and capped with thermostatic air vent or A/VB combination (TAVB) Location of Receiver Fill head is important May or may not require trap down stream of pump Depends upon max system pressure downstream of the control valve

Closed Loop Receiver Sizing

Double Duty® Steam Trap/Pump Combination

Double Duty® - 4 Double Duty 4 1” x 1” Ductile Iron Pump Up to 350 lb/hr pumping capacity Up to 4,000 lb/hr trapping capacity Integral trap/pump mechanism – single float Max pressure is 72 psi

Double Duty® - 6 Double Duty 6 1-1/2” x 1” 150# flanged Carbon Steel Pump 200 psig rated body 200 psig max operating pressure Separate pump and trap mechanisms Up to 4,800 lb/hr pumping capacity Up to 22,000 lb/hr trapping capacity External motive/vent seats Inconel X-750 Springs

Double Duty® 12…

Double Duty Closed Loop Application Double Duty® Steam trap/pump combination

Double Duty® 12 100% turndown application…

Closed System Advantages: No flash steam loss No need to run long expensive vent lines No electric pump problems (seals, motors, etc.) Return condensate hotter Precautions: Dedicated pump for a single piece of equipment Can not use air as motive force

Open (vented) System

Double Duty Vented System – No Internal Trap Mechanism Double Duty™ 6 Steam trap/pump combination

Open System Advantages: Important notes: Drain Multiple pieces of equipment Can use Air or Steam for pump trap operation Easiest to understand Important notes: Modulating steam sources must drain by gravity to receiver inlet (no lifting of condensate) If installing a Pressure Reducing Valve (PRV), outlet of PRV must be a minimum of 10 feet from pump inlet. If room doesn’t permit, add an accumulator pipe. Add a vacuum breaker on discharge side of heat exchanger and a thermostatic air vent at high side of exchanger (if not designed to run in vacuum) Add necessary auxiliary equipment…water level gauges, pressure gauges, receiver overflow, discharge gate valves, drains for receiver/pumps etc

Considerations for open systems Receiver sizing Receiver must be sized to provide adequate separation of flash steam and condensate Vent sizing on receiver Vent line velocity of 3,000 – 4,000 FPM Location of Receiver Fill head is important Prevent flashing in the pump trap Vent connection on pump too small to vent atmospheric flash steam of any quantity Could build pressure inside pump body affecting flow into the pump

Vented Receiver Sizing (assumes straight up vertical piping)

Flash Recovery Not just a lot of hot air

Uses of flash steam… Atmospheric vent condenser Preheat coils Preheat water/glycol or other media Preheat coils Supplement existing lower pressure steam lines Recover flash to Deaerator Flash vent condenser on a DPT-3512LBRPI-24-12

Flash Steam Calculation 50 psig pressure 0 psig pressure % of flash steam = 267.5 – 180.07 x 100 970.3 % of flash steam = 9.01% If our condensate load is 2000 lb/hr, the flash steam produced would be: Flash steam produced = .0901 x 2000 or 180 lb/hr of flash steam 267.5 Btu/lb 180.07 Btu/lb

Flash Steam Graph

Flash Steam Savings Calculator Armstrong Steam-A-ware CD

Armstrong VAFT Vertical Flash Vessels Excellent for providing low velocity flash steam with no water carryover ASME Sec. VIII U stamped to 150 PSI (other pressures upon request) Models include: VAFT-6 VAFT-8 VAFT-12 VAFT-16

Armstrong HAFT Horizontal Flash Vessels Excellent for providing low velocity flash steam with no water carryover HAFT-4 HAFT-6 HAFT-8 HAFT-10 HAFT-12 HAFT-16 HAFT-2448 HAFT-2472 HAFT-30 ASME Sec. VIII U stamped to 150 PSI (other pressures upon request) No internal baffling

Engineered Solution