Gas separation: processes – Deflecting – Centrifugal force
Reexamination Certificate
2000-09-11
2002-10-29
Hopkins, Robert A. (Department: 1724)
Gas separation: processes
Deflecting
Centrifugal force
C055S323000, C055S337000, C055S300000, C055S334000, C055S315000, C055S341100, C055S419000, C055S486000, C055S459100
Reexamination Certificate
active
06471751
ABSTRACT:
1. CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable
2. FIELD OF THE INVENTION
This invention relates to vacuum collectors, specifically to cyclonic vacuum collectors employing HEPA (High Efficiency Particulate Air) filters to achieve large-scale environmental remediation.
3. BACKGROUND
3.1. Environmental Remediation: A Critical Problem Accompanying Sandblasting
Sandblasting is an important preliminary to the painting of large metallic structures, e.g., bridges. Sandblasting removes old paint and cleans the bridge to be painted. Sandblasting produces large quantities of reactive, toxic dust. Significant amounts of neurotoxic lead, carcinogenic chromium, and other highly toxic materials make this dust very dangerous. Collecting paint dust from sandblasted bridges in a safe manner is necessary and presently extremely difficult. Federal regulations require that vacuum collectors picking up paint dust have HEPA filters to ensure their exhaust is better than 99.97% free of dust particles greater than 0.3 micron in diameter. At present, there are no small portable vacuum collectors that can pick up large amounts of sandblasted materials according to these federal regulations. Therefore, there is a great need for a portable vacuum collector, which protects the sandblaster and enables environmental remediation in accordance with the law.
3.2. Environmental Remediation: A Critical Global Problem
Bridge-sandblasting does not alone pollute the environment. Many economic activities, such as manufacturing, building, infrastructure maintenance, etc., create toxic byproducts which are dispersed in the land, sea, and air. These toxic byproducts harm or destroy life and, with economic activities across the globe at historical maxima, the remediation, i.e., the cleaning and restoration, of the harmed environment is now a critical planetary need.
Solids, such as heavy metals (e.g., lead, mercury, chromium, zinc, etc.), chemical compounds of heavy metals, asbestos, other toxic substances, etc., occasionally mixed with liquids, are a major part of environmental pollution. The best way to deal with such materials is to pick them up using the precise action of a vacuum collector or cleaner, transfer them to a container, and seal and bury this container, in a suitable place.
The vacuum collector this cleaning operation requires is small but powerful, armed with a HEPA filter, which insures exhaust air of high purity, and able to handle large-scale cleaning, including dust removal, nonstop. The desired vacuum collector is also simple as well as inexpensive, to buy and operate, since a significant amount of solid pollutants is created by small contractors, manufacturers, builders, and others, who lack the resources to conduct complicated, costly remediations. As the following discussion of the prior art shows, this vacuum collector is presently unavailable, and this lack both prevents enforcement of federal environmental standards and destroys the environment.
3.3. Prior Art
(a) U.S. Pat. No. 4,753,639 to Johnstone describes a vacuum loader employing an air blower, a filtering module, and a debris collector. The blower sucks debris-laden air into the debris collector, some of the debris is gravitationally deposited in the collector, the partially cleaned air then goes through the filters and ultimately into the atmosphere. Lack of powerful cyclonic cleaning, among other things, makes this vacuum loader unsuitable for challenging operations.
(b) U.S. Pat. No. 4,133,658 to Callewyn describes a dust collector employing a single cyclone-producing module, which is mounted on a dust collector, and a blower. The blower sucks dust-laden air into the cyclone module, the air spins depositing dust into the dust collector below, and then goes through a vortex device inside the cyclone chamber, out of the cyclone chamber, into an external filter bag, and finally into the atmosphere. Although more potent than analogous non-cyclonic appliances, this appliance cannot efficiently clean heavily contaminated areas, because, among other deficiencies, it has only one cyclone.
(c) U.S. Pat. No. 5,080,697 to Finke describes a pull-down vacuum cleaner of one module containing a conical cyclone generator as well as primary and secondary filters, with the primary filter covering the bottom of the module. A vacuum pump sucks contaminant-laden air into the module, the air-stream strikes the cone, spins into a cyclone, deposits contaminants on the primary filter below, and goes through the primary filter, eventually through the secondary filter, and finally into the atmosphere. Although this vacuum cleaner minimizes size by artfully combining cyclonic cleaning, contaminant storage, and primary as well as secondary filtration within a single module, its peculiar use of the primary filter surface as contaminant storage site renders it unsuitable for rapid, efficient cleaning of heavily contaminated areas.
(d) U.S. Pat. No. 4,790,865 to DeMarco describes dust collectors employing, among other components, a single cyclone module mounted on a dust collector and another distant but communicating module containing filters; a device accelerating dirty air before it goes through the filters is an optional part of the filter module. Dust-laden air is sucked into the cyclone module, the air spins, deposits dust in the dust collector below, then travels through a hose to the filter module, through the components of the filter module, and finally into the atmosphere. With only one cyclone, this dust collector lacks the power for challenging cleaning operations.
(e) U.S. Pat. No. 4,820,315 to DeMarco describes a complicated vacuum loader of many moving parts, employing, among other things, (1) a prior art cyclone-producing module mounted on a bagger, which collects and packages contaminants in bags, (2) a second prior art cyclone-producing module, communicating with the first, mounted on another contaminant storage module, (3) a complex device, comprising dual valves, tubes and hoses, for transferring contaminants gathered in the contaminant storage module back to the bagger, (4) a third module containing primary filters mounted on the second cyclone module, and (5) a fourth module containing secondary (HEPA) filters, distant from the module containing the primary filters but communicating with it through a pipe or hose. (The patent also describes another similar vacuum loader, which lacks the fourth module housing the secondary filters, and which places either primary or secondary filters in the third module.) In operation contaminant-laden air is sucked into the first cyclone chamber, the air spins, deposits contaminants into the bagger below, enters the second cyclone chamber, spins, deposits additional contaminants into the collection module below, then goes through the primary filters above, through the pipe or hose, through the module containing secondary filters, and eventually into the atmosphere. Contaminants gathered in the collection chamber below the second cyclone are transferred back to the bagger, through operation of the complex device mentioned above, and eventually bagged.
Although this DeMarco loader features two communicating cyclone chambers, it comes with many components and great complexity, which combine to decrease usefulness in several ways.
First, cleaning the secondary (HEPA) filters of the loader, an important maintenance task, can be messy and dangerous, because the secondary filters are separate from the primary filters, in a distant module lacking a contaminant storage chamber. For to clean these secondary filters, the filters must first be taken out of the module housing them. And when they are taken out and cleaned, contaminants adhering on the filters fill the air and proceed to land nearby, which is primarily the face of the person cleaning the filters. Contaminants, especially toxic contaminants, on the face or in the lungs of the operator of the loader, every time the secondary filters need cleaning, is an important limitation of the DeMarco loader.
Second, the loader is less durable and more expensiv
Lunardini John M.
Semanderes Stavros
Hopkins Robert A.
Houston Industrial Corporation
Petrakis Konstantinos
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