Attachment 6- Green Chemical.docx

ATTACHMENT 6 – GREEN CHEMICAL FORMULATIONS

GREEN CHEMICAL TREATMENT PROGRAM FOR HEATING AND COOLING SYSTEMS

Cooling Towers

The green chemical treatment for cooling towers is formulated with polyaspartate (PASP) to inhibit scale formation. This class of water-soluble polymer compounds inhibits the formation of calcium carbonate, calcium sulfate, and barium sulfate. It is a replacement for the less environmentally friendly polyacrylates, which are inexpensive and versatile, but are environmentally persistent, lasting virtually forever. The PASP compounds are more environmentally acceptable on the production end; production uses no organic solvents, and is extremely efficient and virtually waste-free. They are also degradable over time with bacterial action.

The treatment formulation will also contain additional phosphonate materials and an azole supplement for copper corrosion protection. Sodium molybdate is allowed as a trace element for dosage control only, with a maximum residual of 1.0 ppm. A substitute trace element may be substituted only if molybdate is not permitted by local or state regulations.

Corrosion shall be monitored with a corrosion coupon rack with the objective of limiting corrosion rate to a maximum of 2 mils per year for mild steel and 0.2 mpy for copper alloys.

No acid materials for pH control shall be allowed. The system shall be maintained to carry three to three and one-half cycles of concentration, with a maximum total hardness level of 600 ppm and a maximum silica level of 160 ppm. The combined total calcium hardness and total alkalinity level should not exceed 900 ppm.

For biological control, an automated dual biocide program shall be provided, with the system programmed to apply the biocide three times per week during the hotter months (9) and two time per week during the remaining cooler months (3). The non-oxidizing material shall be the Presidental Green Chemistry award winner material tetrakis (hydroxymethyl) phosphonium sulfate (THPS), an excellent bactericide. THPS is a broad-spectrum, non-foaming microbiocide. The compound has an environmentally benign toxicity profile and degrades rapidly upon discharge, to nontoxic components. THPS does not bioaccumulate and, therefore, offers a reduced risk to higher life forms.

The second biocide material should be an oxidizing material fed two times per week during the hot months and 1 time per week during the cooler months, to control algae, and should be automatically controlled with an ORP system and a free chlorine test to maintain 0.2 to 0.5 ppm free chlorine for 4 hours. Periodically, the oxidizing material should be increased, with the specific objective of sanitizing the cooling tower for potential Legionella bacteria.

Closed Loops

All closed chill water and hot water loops shall be chemically cleaned with an alkaline, phosphate formulation containing dispersants, iron sequestrants, and surface-active materials, and then thoroughly flushed. After complete flushing, each closed system is to be treated with a liquid nitrite/borate corrosion inhibitor based formulation, with 600-800 ppm nitrite in the chill loop and 800-1200 ppm nitrite in the hot water system.

Steam Boilers

For steam boilers, a complete automated proportional feed system is required to apply three chemicals for pretreatment, internal treatment, and corrosion protection.

All formulations shall be in liquid form, and applied directly to the feedwater tank through a stainless steel injection quill, with the exception of the ethoxolated soya steam line chemical which shall be injected through a stainless steel injection quill plumbed direct to the steam header (in the common steam header area if there are multiple boilers). Note: The plumbing from the chemical pump applying the sodium sulfite should be plumbed not only to the feedwater tank, but also to each boiler (with a shutoff valve) so that proper off-line and storage procedures may be utilized to protect the boiler(s) from oxygen corrosion at all times. All chemical plumbing should be in 3/8 inch 316 stainless steel. This requirement is only for the oxygen scavenger.

The internal treatment formulation shall include phosphate, polymer, and phosphonate materials to provide scale and deposition protection and will be applied direct to the boiler feedwater. The ethoxolated soya steam line chemical shall be injected through a stainless steel injection nozzle direct to the steam header.

Steam boiler feedwater temperature shall be regulated with a temperature-regulating valve to maintain feedwater temperature no less than 180 degrees Fahrenheit, and soft water (less than 2 ppm total hardness leaving the softener) shall be supplied for each steam boiler by the base facility.

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