Problems Arising from Entrained Air in White Water
Air that is entrained in white water or paper making stock can lead to the formation of circular holes or pin holes on paper. It also results in reduced dewatering rates and deposit problems from foam buildup. Overflow of foam in paper manufacturing stock from tanks can result in the loss of solid material.
Classes of Air that Concern Paper Manufacturers
There are three main classes of air that affect paper manufacturing are entrained air, dissolved air and large bubbles. Dissolved air acts as part of the water phase. When there is a pressure drop, dissolved air can come out of the solution in the form of tiny bubbles or entrained air. There are bubbles present in the entrained air that are small enough to flow with the fibers. On other hand, large bubbles buoyant enough to rise to the surface of the white water or papermaking stock. These bubbles pose a problem, when they are persistent and accumulate as visible foam or froth.
Mechanical Factors Contributing to Foam Problems
Apart from chemical factors, mechanical factors causing air problems include leaky seals on pumps, which is a primary reason for unnecessary air entrainment. Paper machine environment plays a vital role in foam formation, where contributing elements are air, water, agitation, splashing and stabilizers. When it comes to a traditional paper machine, the release of air takes place due creaming, coalescence and breakage of bubbles in the white water silo and white water tray areas, soon after paper has been manufactured.
Foam Control Solutions for Pulp and Paper Processing
Defoamers for the pulp and paper industry developed by Trio Chemicals are particularly formulated to promote coalescence of air bubbles within white water and papermaking stock as well as break bubbles at the water surface. Trioban range of defoamers offer different products that may be required in different paper machine environments. These defoamers improve the quality and uniformity of paper, avoid formation of holes, reduce paper breakage, prevent overflow in storage pool and control loss of wet chemicals and fibers. Trioban range of antifoams and defoamers are environmentally friendly products that meet the needs of the paper and pulp industry. Trioban antifoams deliver high performance and are easy to handle. Some of the defoamers for pulp and paper are listed below:
1. TRIOBAN F 695 is a non-silicone defoamer and a paper stock deaerator, which is effective in clean running of the paper machine, where it helps to disperse soil floatation and does not affect sizing or paper strength. TRIOBAN F 695 has an excellent drainage and knockdown property with low toxicity.
2. TRIOBAN F 083 is a silicone free defoaming agent designed for use in headbox for immediate foam control. It helps to disperse soil floatation and does not lead to pitch accumulation. TRIOBAN F 083 is very effective on paper machine at stock temperature in the range of 30°C to 50°C.
3. TRIOBAN 2020 EM is a non-silicone antifoam for general chemical processing applications. It is used for paper machine, pulping process and absorbent paper industries. TRIOBAN 2020 EM provides immediate foam control for wire pit.
4. TRIOBAN 2SD XL is an economical grade non silicone antifoam for the pulp and paper industry that has a great knock down ability and long-term efficiency. It is formulated for use in clarifiers and aeration tanks of effluent treatment plants, where silicone is not tolerated.
5. TRIOBAN F 35 is a silicone based antifoaming agent that finds applications in the pulp and paper industry. It is suitable for brown stock washing and exhibits excellent knock down properties over wide range of pH. TRIOBAN F 35 is designed to work in hot alkaline process system like kraft pulp washing.
6. TRIOBAN PP 30 is a silicone based defoamer for the pulp and paper industry used in paper effluent treatment plants. It must be added continuously for foam free process in aeration tanks and clarifiers. TRIOBAN PP 30 is ideal for effluent treatment plants, where it can be automatically dosed, when product is needed through dosing pump.
7. TRIOBAN P 1403 is a silicone antifoam with excellent deaeration effect and foam control. It reduces 15% to 20% soda ash content and is highly compatible at high temperature up to 110°C as well as extreme pH in range of 4 to 12.TRIOBAN P 1403 is effective at low concentrations and facilitates smoother pump operations in the paper and pulp industry.
8. TRIOBAN E 27 D is a versatile non silicone antifoaming agent used in effluent treatment plant and pulping process. It shows excellent performance in paste form, where silicone is not required.
9. TRIOBAN ULTRA 15 is a silicone based antifoaming agent used for foam control and chemical processing in the pulp and paper industry. It has good shear resistance and delivers persistent foam control action.
10. TRIOBAN PC NSDL is a silicone free defoamer used for coating in the paper and pulp industry. It is dispersible in water to give emulsion of moderate stability. TRIOBAN PC NSDL improves printability and runability.