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Energy Program
ESA-164 Amalgamated Sugar FINAL PUBLIC REPORT PDF Print E-mail
Written by USDOE Energy Efficiency & Renewable Energy   
Friday, 15 July 2011 09:20

ESA-164 Amalgamated Sugar FINAL PUBLIC REPORT:

Introduction:

The Amalgamated Sugar Company’s Nampa, Idaho facility processes 12,500 tons of sugar beets per day. The plant produces 20,000 cwt of granulated sugar, 25,000 cwt of thick sugar juice, and 600 tons of dried pulp.

The factory has three coal-fired boilers, one gas-fired boiler, two turbine-generators, and several mechanical drive steam turbines. Process uses of steam include several multi-stage evaporator trains, sugar crystallization pans, numerous heaters, and a new steam pulp dryer. The predominant fuel is coal, although natural gas is the impact fuel for most of the energy savings opportunities during the annual 125-day sugar beet campaign.    The plant self-generates most of its electric energy needs with two backpressure turbine generators. The plant imports approximately 2.8 MW (annual average).

Objective of ESA:

The objective of the Energy Savings Assessment (ESA) was to:

  • Perform an abbreviated Energy Savings Assessment using the DOE’s suite of Steam Tools, and
  • Train the staff in the use of the Steam Tools so that they can identify additional energy savings opportunities after the Energy Savings Assessment.

Focus of Assessment:

Coal- and gas-fired power boilers, steam turbines, associated steam systems, process uses of steam

Approach for ESA:

The approach of the training assessment was to provide training on DOE Steam Tools suite and use them to identify and analyze potential opportunities.

  • Identified opportunities and best practices using the Steam System Scoping Tool
  • Modeled parts of the steam system using the Steam System Assessment Tool
  • Used SSAT to estimate savings from opportunities identified in SSST
  • Demonstrated the use of E3PLUS to evaluate insulation-related opportunities

General Observations of Potential Opportunities:

Annual Energy Consumption:
In the 2005 sugar season Amalgamated Sugar consumed 2.45 TBtu of coal and 0.78 TBtu of natural gas1. The impact fuels for this energy savings assessment are natural gas during the 125-day annual sugar beet campaign and coal during the rest of the year.

Energy Source 2005 Consumption (MMBTU)
Natural Gas 78,964
Electricity 85,325
Coal 2,448,020
Total 2,612,309

 

 

 

 

1 1TBtu=1TeraBtu=1x1012 Btu

Energy Savings Opportunities:
1. Improve Boiler Efficiency by Decreasing Excess Oxygen (all boilers) – There is an opportunity to improve the efficiency of all four boilers by lowering the amount of excess oxygen used in combustion. The plant should consider measuring carbon monoxide during the boiler tuning efforts. The presence of carbon monoxide indicates the presence of unburned fuel in the boiler furnace.
2. Improve Boiler Efficiency by Decreasing Boiler Blowdown (all boilers) – There is an opportunity to decrease blowdown losses and thus increase the efficiency of all four boilers. This opportunity is consistent with a recent recommendation from NALCO. NALCO’s John Deverall gave the assessment team useful guidelines and suggestions regarding both boiler blowdown and blowdown heat recovery.
3. Install Blowdown Flash Tank to Produce Low Pressure Steam (Union boiler) – There is an opportunity to recover some of the waste heat in the boiler blowdown. The blowdown could be sent to a new flash tank to produce low pressure flash steam. The flash steam would be used to heat boiler feedwater or other process streams.
4. Modify feedwater heat recovery exchanger using boiler blowdown (Riley and B&W boilers) – There is an additional opportunity to recover waste energy from the boiler blowdown. A heat exchanger installed in the blowdown line would recover waste heat that would be used to heat boiler feedwater or other process streams.
5. Improve Insulation – There appears to be a significant opportunity to save fuel by improving insulation throughout the factory. Three discrete projects were modeled during the assessment to provide training on DOE’s insulation software tool. A comprehensive insulation audit is beyond the scope of this abbreviated assessment; however, we developed plant-specific rules of thumb that can be used to estimate savings from several different types of insulation opportunities.
6. Multiple boiler optimization – There is an opportunity to optimize boiler operation during the sugar beet campaign. The optimization project would yield increased steam production from the low-cost, coal-fired boilers and decreased production from the gas-fired unit. The scope of the optimization project could include a range of software and hardware solutions, from a relatively simple spreadsheet model to an automatic boiler optimization control system.

Additional Potential Opportunity:
Several other opportunities were discussed during the training assessment. Some of these opportunities are not included in this report because the simple payback period was unattractive. One other potentially attractive opportunity was explored, although a full analysis of this project is beyond the scope of the three-day training assessment.

Excess condensate heat recovery – The factory pumps approximately 500 gpm of hot (185 F) excess condensate to a cooling pond. If the factory could find a use for this waste heat, it could recover approximately 25 MMBtu/h in heat and offset approximately 30 MMBtu/h in boiler fuel.
 

Implementation Considerations:
The potential energy savings opportunities summarized on page one include estimated time horizons for implementation. The opportunities are categorized as near-term, medium-term, or long-term according to the general guidelines below.

  • Near-term opportunities include actions that can easily be attained in less than one year. Examples include improvements in operating activities, equipment maintenance, and relatively low cost actions or purchases.
  • Medium-term opportunities would typically require one to two years to implement and would require additional engineering and economic analysis. Examples include capital equipment purchases and moderate changes to the plant’s steam system or processes.
  • Long-term opportunities typically require two to five years to implement. Examples include new technologies or significant changes to either the steam system or the plant’s processes.

The potential savings opportunities can be categorized as follows:

Time Horizon % of Savings Opportunities
Near-term 77
Medium-term 23
Long-term 0

 

 

 

Management Support and Comments:

Amalgamated Sugar took a very active interest in the training assessment. They will use the DOE Steam
Tools to identify additional opportunities to reduce their energy costs.

DOE Contact at Plant/Company:
Scott Kahre, Process Engineer, 208-468-6885, This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

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