Chemical Plant Assessment Uncovers More Than $3 Million in Potential Savings
From the Spring 2006 issue of Energy Matters
The Solutia chemicals manufacturing plant in Springfield, Massachusetts, is the largest one in New England.
Using a unique method known as "SECURE," an energy assessment team found ways to reduce the use of steam, electricity, compressed air, and water at a Solutia chemical plant and save nearly 340,000 million Btu (MMBtu) of natural gas per year.
A plant-wide energy assessment at Solutia Inc.'s chemical production facility in Springfield, Massachusetts, uncovered opportunities to save nearly $3.3 million in energy costs there annually. Implementing all the potential projects identified would save an estimated 9.6 million kilowatt-hours (kWh) of electricity and more than 338,000 MMBtu of natural gas each year. The initial investment required would be $6.3 million, so the project would pay for itself in about 2 years.
The assessment team used the company's Steam, Electricity, Cooling Utility Reduction Exercise (SECURE) method to address energy generation and use. With this method, Solutia's team could focus on reducing the use of steam, electricity, compressed air, and water at the entire site, considering the site as an integrated entity rather than as a collection of individual processes.
Benefits
- Identified approximately 9.6 kWh in electricity savings per year
- Uncovered opportunities to save 338,000 MMBtu in natural gas annually
- Could save $3.3 million in energy costs annually
Solutia's energy management team conducted the assessment to ensure that plant processes are designed to save as much energy as possible while generating less waste.
The U.S. Department of Energy's (DOE) Industrial Technologies Program (ITP) cosponsored the assessment through a competitive solicitation process. ITP's BestPractices promotes plant-wide energy-efficiency assessments that will lead to improvements in industrial energy efficiency, productivity, and global competitiveness while reducing waste and environmental emissions. In this case, ITP shared $100,000 of the total $305,000 assessment cost.
About the Plant
Solutia manufactures polymers, intermediates, and chemicals; it was formed in 1997 from one of the Monsanto Company's chemical divisions. Solutia produces performance films for laminated safety glass and after-market film applications and manufactures specialty products such as water treatment chemicals, heat transfer fluids, and aviation hydraulic fluid.
Solutia's 180-acre Springfield facility, the largest chemical manufacturing facility in New England, employs about 500 workers. Its management takes an active interest in energy conservation, safety, and the environment. Therefore, Solutia has established goals to ensure that process designs maximize energy conservation and minimize waste. The site's total annual electricity consumption is about 95 million kWh. Energy generated from natural gas and coal amounts to 1.25 million MMBtu per year, and the site uses 2.5 billion gallons of fresh water annually.
Primary production processes include batch and continuous processing systems and solvent recovery processes that use steam-intensive distillation. Production processes focus on the manufacture of polymer resin and chemicals, extrusion of the resin into sheet, and related applications. The utility generation and distribution facility is centralized. Utilities generated on-site include steam (from coal and natural gas), electricity, compressed air, and nitrogen. An on-site cogeneration facility, owned and operated by Mass Power, supplies steam.
Solutia found ways to save millions of dollars each year by reducing its fuel and electricity usage.
Assessment Approach
The assessment team was made up of Solutia's process experts, utility engineers, research and development scientists, cost estimators, accountants, process and project engineers, and external consultants. They used the Steam, Electricity, Cooling Utility Reduction Exercise (SECURE) method to address both the process and utility sides of the site's operations. This method considers the site as an integrated entity rather than a disparate collection of individual processes.
For production processes, the assessment team collected data on steam, electricity, water, and wastewater usage and costs. They also compiled data on energy use for individual process equipment. They then analyzed this information to identify primary energy users and each one's potential for energy savings.
Then the team evaluated opportunities to reduce the amount of energy used by the equipment and processes that had been identified as significant energy users. To do so, the team reviewed earlier ITP plant-wide assessment case studies, compiled a list of energy savings ideas and best practices, and evaluated the potential for integrating equipment. For example, they looked at whether hot effluent from a distillation column could be used to preheat feed to the column. Finally, the team considered site-wide projects such as recycling steam condensate, which would have an impact on several different processes.
Assessment Results and Identified Projects
The analysis resulted in an initial list of about 80 potential projects. These were pared down to about 30 projects that were determined to be technically and commercially feasible. A more detailed description of some of the projects follows.
Project 1. The assessment team used a chilled water system simulation model to determine the range of optimum operating temperatures for chiller and cooling tower water based on ambient conditions. The team recommended resetting chiller water temperature set points.
Project 2. The team recommended installing a new high-capacity pilot on the burner system in a gas boiler so it could operate at a lower minimum fire level. The pilot would allow the boiler to ramp up to required operating conditions more quickly and would ignite the fuel immediately, without the need for purging. Steam is supplied primarily by a coal boiler, although a gas boiler can also supply steam when the process load fluctuates. Solutia's gas-fired boiler has a relatively high minimum fire level because its burner system is almost 30 years old.
Project 3. The team recommended connecting the preheating systems of coal and gas boilers to transfer the heat load from the gas-fired boilers to the coal-fired boiler whenever the gas-fired ones are producing steam. The coal boiler has a feedwater preheating system; the gas boilers do not. So, fuel burned in the gas boilers provides both the latent heat of vaporization and the sensible heat needed to increase the feedwater temperature to the boiler's operating temperature. However, the sensible heat needed for the gas boilers can be derived by using coal-generated steam rather than burning natural gas.
Project 4. The team recommended repairing any steam traps that were blowing through, leaking, plugged, or flooding—in other words, any that were failing. They found that, out of 700 traps inspected, about 100 had failed.
Project 5. The team recommended retrofitting fluorescent light fixtures with new electronic ballasts and replacing older T12-style light bulbs with high-efficiency T8 bulbs. They also recommended replacing metal halide high-intensity discharge lamps with new, higher efficiency metal halide lamps.
Project 7. The assessment team recommended capturing waste heat from the air compressors and using it to preheat the boiler feedwater. Inadequate air coolers could also be replaced with two new plate-type heat exchangers. The air compressors in the site's centralized air compressor system currently generate a significant amount of waste heat. The compressors have a closed-loop cooling system; coolant-to-air heat transfer is done by means of several undersized heat exchangers. The heat exchangers operate at elevated temperatures in summer and so must be cooled by a water spray system.
These and the other potential projects could save Solutia more than $3 million in operating costs each year and significantly reduce energy usage at the plant. For more, see the full case study (PDF 979 KB). Download Adobe Reader.
Project Partners
Solutia Inc.
Springfield, MAIMS Engineering
Chapin, SCNational Environmental Technology Institute, University of Massachusetts
Amherst, MAPolymer and Chemical Technologies
Pensacola, FL
For more information on plant assessments and reducing your natural gas usage, visit the ITP BestPractices Web pages.
| Project Number | Project Description | Cost Savings ($/year) | Capital Cost ($) | Payback (years) | Fuel Savings (MMBtu/year) | Electricity Savings (kWh/year) |
|---|---|---|---|---|---|---|
| 1 | Optimize chiller water temperatures | 46,000 | NA | NA | NA | 536,000 |
| 2 | Upgrade boiler burner system | 240,000 | 70,000 | 0.3 | 89,000 | NA |
| 3 | Transfer heat load for feedwater preheating from gas-fired to coal-fired boiler | 25,000 | 60,000 | 2.4 | 9,000 | NA |
| 4 | Repair steam traps | 151,000 | 60,000 | 0.4 | 29,000 | NA |
| 5 | Upgrade lighting fixtures | 78,000 | 130,000 | 1.7 | NA | 918,000 |
| 6 | Install new cooling tower to reduce process water usage | 750,000 | 3,200,000 | 4.3 | NA | NA |
| 7 | Use air compressor waste heat to preheat boiler feedwater | 208,000 | 58,000 | 0.3 | 35,000 | 159,000 |
| 8 | Reduce boiler blowdown frequency and automatically control blowdown | 9,000 | 8,000 | 0.9 | 1,700 | NA |
| 9 | Recover boiler heat and water losses | 376,000 | 296,000 | 0.8 | 82,000 | NA |
| 10 | Recycle steam condensate | 396,000 | 608,000 | 1.5 | 62,000 | NA |
| 11 | Recycle process cooling water to the power plant | 195,000 | 160,000 | 0.8 | 21,000 | NA |
| 12-23 | Install variable frequency drives on chilled water pumps, cooling tower water pumps, cooling tower fans, chiller motors, hot water pump east, boiler feedwater pump, biofilter supply fan, dryer exhaust fan, biofilter scrubber pump, boiler fans, and B crude pump | 555,000 | 1,295,000 | 2.3 (avg.) | NA | 6,505,000 |
| 24-27 | Install variable-air-volume systems on process air-handling units | 136,000 | 198,000 | 1.5 (avg) | 2,700 | 819,000 |
| 28 | Recover air knife waste heat | 33,000 | 90,000 | 2.7 | 6,200 | |
| 29 | Upgrade air knife blowers | 6,000 | 22,000 | 4 | NA | 66,000 |
| 30 | Optimize air knife blower system | 32,000 | 60,000 | 1.9 | NA | 378,000 |
| 31 | Automate control of extrusion process supply and wind fan to operate fans only when needed for process conditions | 27,000 | 9,000 | 0.3 | 500 | 173,000 |
| Total | $3,263,000 | $6,324,000 | 2 (avg) | 338,100 | 9,554,000 |
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