The Economical and Process Benefits of Steam-System Audits

Sep 16, 2009

Steam is a valuable resource in pharmaceutical manufacturing facilities. Plant steam is important for process-heating applications, and clean or pure steam is often used for sterilization. A clean- or pure-steam system provides the correct quality and purity of steam at the required operating parameters on demand. Investing time and money in auditing and optimizing a steam system can pay off quickly, especially because the costs of energy, maintenance, and downtime are steadily rising.

Clean- and pure-steam systems
Clean steam, which is needed for applications such as pharmacopoeia grade water for injection and pharmaceutical synthesis, is expensive to generate. It is created through a complicated, resource-intensive process. It follows that the costs of clean-steam system problems are high, and auditing a clean-steam system makes good economic sense. Periodically verifying that the system is run according to best practices helps to ensure optimal maintenance and uptime. This strategy also helps maintain the purity, quality, and thermal control of the clean steam.

Clean-steam systems must conform to American and international good manufacturing practice, engineering guides, and other regulatory (e.g., US Food and Drug Administration and World Health Organization) guidances for water. A review of the system’s operation, installation, and performance can improve the system, ensure continued and reliable output, maintain regulatory compliance, and identify preventive-maintenance activities.

The audit process can improve the clean- or pure-steam system by including the following activities:

  • Comparing blueprints with the site’s installation
  • Verifying trapping locations and condensate removal
  • Testing steam quality
  • Checking steam-trap operations
  • Examining piping configurations such as dead legs, valve orientations, process-equipment interfaces, slopes, and drains
  • Monitoring and investigating corrosion
  • Evaluating system integrity
  • Assessing gasket and material selections
  • Testing steam-conditioning stations
  • Monitoring pressure-relief and safety systems
  • Checking insulation and energy management
  • Inspecting welds.

Failing to review or control the above items may decrease steam quality and, ultimately, system performance.

Malfunctioning or misapplied clean-steam traps affect energy consumption and process integrity. A steam trap that cycles too rapidly or has failed open can result in the following problems:

  • Increased fuel bills
  • High emissions from unnecessary combustion of boiler fuel to replace the heat energy lost through the trap
  • Increased feedwater use
  • Inefficient operation of the clean- or pure-steam generator
  • Increased water-vapor emissions into plant environments.

A trap that is cycling too slowly or has failed closed results in the following problems:

  • Backup of condensate, which is a high risk factor of not attaining specified process temperature and maintaining specified time-at-temperature for steam-in-place applications
  • Poor-quality or wet steam
  • Water hammer, which is dangerous to plants and personnel
  • Increased maintenance
  • Increased startup or sterilization times
  • Increased production time and unit costs
  • Reduced process performance and plant efficiency
  • Increased production-system failures and reject rates.

Regularly scheduled trap surveys not only realize substantial savings, but also significantly improve process efficiency and reduce environmental concerns.

Steam-system audits
A steam-system audit should be tailored to an individual process or application. Auditors should begin by meeting with plant managers to explore strategies to improve performance and efficiency. After a preliminary discovery phase, auditors should determine and prioritize audit strategies, with the goals of reducing operational costs by managing steam systems according to best practices and resolving health and safety concerns.

The audit process can include the plant’s steam-distribution loop or the clean-steam system. Audit teams often use an advanced steam-system assessment tool in the form of modeling software developed by the US Department of Energy and a private consortium.

The steam-system audit report should highlight recommended actions and estimate the return on investment. The report should include an objective analysis to guide decisions about further actions. The audit report also should include the following items:

  • Inventory of key equipment
  • Identification of poor engineering practices and advice on best practices
  • Health and safety considerations
  • Recommendations for reducing emissions and saving energy (e.g., by eliminating steam leaks, replacing misapplied or incorrectly sized equipment, repairing failed steam traps, recovering heat from the flash steam, installing or repairing insulation, and reducing fuel and make-up water consumption)
  • Comparison of site emissions (e.g., of carbon dioxide, sulfur dioxide, and nitrous oxide) before and after the audit
  • Estimated installation costs
  • Identification of productivity improvements
  • Identification of potential areas for improved product quality
  • Planned preventive-maintenance schedule
  • Site drawings
  • Photographic evidence of items such as misapplied trap types, incorrect and missing components.

Rouging is a common problem and is manifested by red, brown, or violet iron deposits on the heat-transfer surfaces of columns, vessels, and piping. An audit can uncover corrosion-prone areas, establish the extent of corrosion, and suggest remedial actions to reduce corrosion or reestablish a corrosion-free environment.

Proposed solutions to problems found during the audit should be based on conservative economic models. Solutions also should adhere to budgets, production schedules, and resource requirements. These proposals can include supplying and installing replacement parts, designing and implementing efficiency improvements, or a total overhaul of steam-system management. The result of a steam-system audit is a course of action that is economically sound and improves the operational, safety, and environmental aspects of a pharmaceutical manufacturing operation.

Dawn Cartwright Dukes is a product market manager for high-purity steam at Spirax Sarco, 1150 Northpoint Blvd., Blythewood SC 29016, tel. 803.714.2072, fax 803.714.2224, [email protected]

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