Best Practice Guide

Food and Beverage Growers and Processors

Introduction

Planning an Energy Program

Funding and Approval

Commissioning

On-the-Farm Energy Use

Lighting

Building Envelope

Central HVAC System

Boilers

Steam

Energy Use Basics

Pipe Configurations

Proper Maintenance

Waste Heat Recovery

Combined Heat and Power

Compressed Air

Refrigeration

Motors

Demand Response

Distributed Generation

Water Use


Fetzer Vineyard

J Vineyards and Winery

Mission Foods

S. Martinelli and Company

Sara Lee

Vineyard 29


View the Glossary

Steam

Waste Heat Recovery

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Condensate Recovery
Condensate drained and recovered from steam traps can be collected and reused as boiler feedwater. This helps improve overall system as well as reducing boiler operating costs. Four primary points of savings stemming from condensate recovery:

  1. The energy resident in condensate - this is the area where most of the savings are achieved.
  2. Water commodity costs.
  3. Water treatment aspects.
  4. Wastewater charges.

Recovered condensate is, quite simply, distilled water. It is ideal for boiler feedwater since it requires minimal chemical treatment and filtration, saving on water, wastewater, energy, and chemical costs. As described in the chapter on boilers, it takes a great deal of energy to treat and heat feedwater to generate steam. In most cases, reusing condensate is more cost-effective than using new utility water.

Less obvious than water savings, energy savings are realized because it takes substantially less fuel to convert recovered condensate into steam. Utility water typically enters the boiler-steam system at temperatures between 50ºF and 80ºF, and is then heated to more than 212ºF (the boiling point of water). The temperature of recovered condensate, on the other hand, can exceed 200ºF.

A condensate recovery system relies on little additional equipment: receiver tanks to store recovered condensate and help normalize pressure, insulated pipes to return condensate to the boiler, and pumps to move condensate through the pipes.

Flash Steam Recovery
It is possible to divert "flash" steam from the condensate recovery system for use in low-pressure steam applications, like space heating.

Recovered condensate tends to be high pressure and high temperature. As this condensate enters the return system, pressure is reduced. Steam is generated at different temperatures as pressure changes. Thus, as pressure is reduced, liquid condensate at high temperatures causes "flash" steam.

A flash steam recovery vessel installed downstream from the steam trap will collect flash steam and redirect it to an end-use application while directing saturated condensate to return piping.


Resources

U.S. Department of Energy, Best Practices Steam program:

3E Plus - a software program to optimize the installed thickness of mechanical insulation. Helps the user determine fuel savings and emissions reductions under varying operating conditions.

Steam System Scoping Tool - a self-paced checklist for discovering steam improvement opportunities and serves as a scorecard for comparing profiles of one or more plants over time.

Steam Tip Sheets - a series of one-page reference sheets, each of which describes a specific steam improvement opportunity. Tip sheets provide a technical overview and a sample calculation of economic impacts.

Steaming Ahead - this newsletter and companion website give the steam community bi-monthly updates about program products and events.

Ensuring Energy Efficiency Through Effective Monitoring of Steam. Solartron Mobrey Ltd. Reproduced by Energy Solutions Center, Inc., Boiler Burner Consortium.

Yoder, Jesse L., Ph.D. Using Meters to Measure Steam Flow. Plant Engineering Magazine, April 1998. Reproduced by Flow Research, Inc.