Measuring and testing – With fluid pressure
Reexamination Certificate
1998-12-11
2001-11-06
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
C073S061620, C073S866400, C073S053010, C073S061730, C436S148000, C165S011100
Reexamination Certificate
active
06311546
ABSTRACT:
BACKGROUND OF HE INVENTION
The present invention relates to the biofouling of various systems containing aqueous solutions and more particularly relates to monitors to detect or record biofouling and methods of monitoring or detecting biofouling.
Biological fouling on surfaces is a serious economic problem in many commercial and industrial aqueous process and water handling systems. The fouling is caused by a biomass which is the buildup of microorganisms and/or extracellular substances and by dirt or debris that become trapped in the biomass. Bacteria, fungi, yeasts, diatoms and protozoa are only some of the organisms which cause buildup of a biomass. If not controlled, the biofouling caused by these organisms can interfere with process operations, lower the efficiency of processes, waste energy, and reduce product quality.
Cooling water systems used in power-generating plants, refineries, chemical plants, air conditioning systems and other commercial and industrial operations frequently encounter biofilm problems. Biofilm is the buildup of layers of organisms. Cooling water systems are commonly contaminated with airborne organisms entrained by air/water contact in cooling towers as well as waterborne organisms from the systems makeup water supply. The water in such systems is generally an excellent growth medium for these organisms. If not controlled, the biofilm biofouling resulting from such growth can plug towers, block pipelines, and coat heat transfer surfaces with layers of slime, and thereby prevent proper operation and reduce equipment efficiency.
Industrial processes subject to problems with biofouling include those used for the manufacture of pulp, paper, paperboard, and textiles, particularly water laid nonwoven fabrics. For example, paper machines handle very large volumes of water in recirculating systems called “white water systems”. The white water contains a pulp dispersion. The furnish to a paper machine typically contains only about 0.5% of fibrous and non fibrous paper making solids, which means that for each ton of paper, almost 200 tons of water pass through the paper machine, most of it being recirculated in the white water system.
These water systems provide an excellent growth medium for microorganisms, which can result in the formation of microbial slime in headboxes, water lines, and papermaking equipment. Such slime masses not only can interfere with water and stock flows, but when they break loose, can cause spots or holes in the paper as well as web breaks that cause costly disruptions in paper machine operations.
The control of microbial activity has traditionally been the province of toxic chemicals. U.S. Pat. Nos. 3,959,328, 4,054,542, and 4,285,765 are illustrative of the methods that rely on killing the offending microorganisms with toxic chemicals. Such method shave received the majority of the research effort because of the logic of eliminating the problem by eliminating the offending organism and because of the large number of available organic and inorganic chemicals that will kill microorganisms.
Several attempts to control the negative effects of biological activity either avoid the use of toxic chemicals or mitigate their use or impact on the environment. For instance, U.S. Pat. Nos. 3,773,623 and 3,824,184, both to Hatcher et al., relate to the use of the enzyme levan hydrolase to control the formation of bacterial slime in industrial water systems.
While efforts are continually made to control or prevent biofouling, the water systems, and especially the industrial water systems, still need to be shut down for cleaning or removal of the biofouling that has built up and which was not prevented by the introduction of biofouling control compositions. Although the introduction of microbicidal or anti-fouling compositions reduces the number of times a system has to be shut down for cleaning, it would be beneficial to have a biofouling monitoring system which enables the users to determine when biofouling has reached levels which require a shut down and cleaning. Otherwise, if users of the water systems are not aware of the biofouling buildup, such biofouling can result in poor quality products being made such as paper having spots or holes or could even be more detrimental such as a clogging of various lines used to supply feedstock to the water system. Thus, it is most preferred to have an early warning system which informs the users of the water systems of a potentially biofouling situation which needs correction either by the introduction of more chemicals or a shut down. If the users of the water systems know in advance that a shutdown is necessary, then plans can be made ahead of time to finish, for instance, a paper run or to increase the amount of chemicals in the water system to avoid poor quality products or damage to equipment in the water systems.
SUMMARY OF THE INVENTION
A feature of the present invention is to provide a biofouling monitor and methods to detect or monitor biofouling.
Another feature of the present invention is to provide a biofouling monitor system that will detect or monitor biofouling ahead of time in order for corrective measures to be taken.
Additional features and advantages of the present invention will be set forth in part in the description which follows, and in part will be apparent from the description, or, may be learned by practice of the present invention. The objectives and other advantages of the present invention will be realized and obtained by the disclosure particularly pointed out in the written description and the pending claims.
To achieve these and other advantages and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention relates to a biofouling monitor which has a column having an inlet and an outlet. The monitor also has a microorganism nutrient feed line located upstream of the inlet and also has a first pressure sensor located upstream of the inlet for measuring flow pressure and a second pressure sensor located downstream of the outlet for measuring flow pressure.
The present invention further relates to a biofouling monitor which has the above components, namely the column, microorganism nutrient feed line and pressure sensors, as well as a recirculation system connected to the inlet. This recirculation is located downstream of the feed line and is also connected to the outlet for maintaining a pressure feed through the column. In this embodiment, the biofouling monitor also has an inert packing material located in the column. The amount of inert packing material in the column is present in an amount to still permit the passing of liquid containing material through the column.
In addition, the present invention relates to a method to monitor or detect biofouling ahead of time in an aqueous solution. The method includes passing at least a portion of the aqueous solution though a column having an inlet and an outlet. The aqueous solution is generally passed though the column on a continuous basis. A microorganism nutrient is introduced into a portion of the aqueous solution at a point upstream of the inlet. The flow pressures of the-portion of the aqueous solution passing through the column are measured at a first point before the inlet and at a second point after the inlet on a continuous or non-continuous basis, and, the pressure differential based on these measurements is determined. From these pressure differential measurements, the amount of biofouling occurring can be monitored and plotted and a determination can be made whether biofouling is occurring or whether any biofouling that exists is increasing in the aqueous system. The microorganism nutrients being fed into the solution prior to the inlet serves as a way to expedite the biofouling of the aqueous system and thus serves as an early warning mechanism since such expediting of the biofouling serves as a predictor of the biofouling which will occur in the overall aqueous system.
It is to be understood that both the forgoing general description and the fol
Clark Richard A.
Dickinson Wayne H.
Haute E. Van
McNeel Thomas E.
Buckman Laboratories International Inc.
Cygan Michael
Kilyk & Bowersox P.L.L.C.
Williams Hezron
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