Pumps

Two options can prevent the pollution generated by pumps.

Avoiding Sending Hot Material to Storage

Before a temperature-sensitive material is sent to storage, it should be cooled. If this coding is uneconomical because the stream from the storage must be heated when used, hot steam can be piped directly into the suction line of the storage tank pump as shown in Figure 3.10.7. The storage tank pump must be able to handle hot material without cavitating.

Waste B

Waste D

Waste A

Combined Waste Stream

Waste C

Waste E

FIG. 3.10.6 Typical plant mixing of waste streams.

Hot Process Stream

FIG. 3.10.7 Hot stream piped directly into the suction line of the storage tank pump.

Eliminating Leaks

Leaks are a major contributor to a plant's overall waste, especially if the products cannot be seen or smelled. A good way to document leaks is to measure the quantity of raw materials that must be purchased to replace lost stream (e.g., the amount of refrigerant purchased).

Changing the Material of Construction

The type of metal used for vessels or piping can cause color problems or act as a catalyst in the formation of by-products. If this problem occurs, an option is to change to more inert metals. Using lined pipes or vessels is often a less expensive alternative to complex metallurgy. Several coatings are available for different applications.

Monitoring Major Vents and Flare Systems

Flow measurements need not be highly accurate but should give a reasonable estimate of how much product is lost and when those losses occur. Intermittent losses, such as equipment purges, can be particularly elusive. Corrective action depends on the situation. Frequently, a company can reduce or eliminate venting or flaring by installing piping to recover products that are vented or flared and reuse them in the process. Storage tanks, tank cars, and tank trucks are common sources of a vented product. A condenser or small vent compressor may be all that is needed in these sources. Additional purification may be required before the recovered streams can be reused.

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