Fluent material handling – with receiver or receiver coacting mea – With guard or screen for operator
Reexamination Certificate
2001-09-27
2004-05-11
Maust, Timothy L. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
With guard or screen for operator
C141S082000, C141S231000, C052S079100, C052S220100
Reexamination Certificate
active
06732769
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is referred to a modular transportable and easy-to-install compressed natural gas (CNG) re-fueling station for replacing traditional facilities for delivering this kind of fuel by a practical, economical solution.
This modular station is a compact solution including several technologies already used separately in traditional CNG re-fueling stations. With the present invention, these solutions are incorporated in a “micro-package” and are used through the application of security engineering techniques or alternative solutions replacing traditional re-fueling gas station constructions as well as traditional security rules.
2. Description of Related Art
CNG re-fueling stations construction has always involved a potential risk of explosion. This problem has been analyzed in different countries under different point of views.
There are two worldwide trends in the market regarding security standards, the European trend and the American trend. The first one tends to avoid the risk, to avoid the use of elements which may produce risky situations, or to manufacture the elements in such a completely safe way for minimizing the risk of accidents and the consequent risk of deaths. The American trend resides on the cost of the risk, that is, focus the problem on the insurance rate. Americans has issued Rule MPTA 52 which allows the construction of compressed natural gas (CNG) re-fueling stations under a series of rules which are less severe than the Argentine, Chilean, Brazilian or Italian regulations. This has an explanation: it is not possible to build CNG re-fueling stations in urban areas of the United States.
Moreover, the urbanization of the United States cities is much more spacious thus compensating security failures with distances between CNG stations and the urban areas. This would be impracticable in some other countries since there are thousand of very old cities whose general urbanization could not be modified.
In a traditional CNG re-fueling station, bringing natural gas to the station site usually involves the following steps: receiving gas from a natural gas feeding pipeline, measuring the gas flow rate through a traditional gas metering plant, compressing gas up to a predetermined pressure (for instance, 250 bar) using a traditional compressor unit, and storing gas at storing gas vessels. Said gas is channeled to the station fuel pump and delivered at a 200 bar of pressure.
For security purposes, in most countries, the present regulation requires the fulfillment of the following requirements:
a) the compressor unit must be installed inside a concrete bunker;
b) inside said concrete bunker, several security measures must be taken;
c) bunker walls must be constructed with reinforced concrete able to support fire for a minimum period of time of three hours.
The applicant is one of the most important CNG related-technologies company in Argentina. From the extensive experience of the applicant in CNG technologies, it may be concluded that the CNG re-fueling stations need an integral solution avoiding long construction times.
The main object of the present invention is developing a technological solution for overcoming the above cited problems, incorporating all the elements included in a traditional CNG station but in a compact “micro package” solution.
Every CNG station needs a “measurement bridge” for measuring the gas flow the station is taking from the general gas pipeline. A bunker lodging storing vessels, including a compression system, a control and logical switchboard is also needed.
With the proposed invention all these elements are incorporated in a single compact “packaged” unit, that is a single transportable unit.
The most important problem to be solved in this project resides in bringing the “packaged” unit purposed to the same to security level as a traditional concrete bunker of a traditional CNG station. This was definitively a great challenge for the present invention, since said traditional bunkers are usually buried and constructed with reinforced concrete.
In accordance with the applicants' knowledge, in the prior art there are no traces of packaged CNG stations including security features as a traditional CNG station.
U.S. Pat. No. 5,676,180 is referred to a system for delivering natural gas, from a pipeline, is loaded onto a movable transport by flowing the gas into multiple pressure vessels equipped with internal flexible bladders which will contain the gas until the pressure in the vessels equalize with the pressure in the pipeline. At that time, the transport will be moved to a compressed natural gas (CNG) re-fueling station. At the re-fueling station, the multiple pressure vessels will be connected to an un-loading duct leading to the storage facilities. The natural gas will be un-loaded by pressure differential until pressures equalize, then pressurized hydraulic fluid will be pumped into the annulus between the bladder and the steel walls of the pressure vessel which will deflate the bladder and squeeze the remaining gas out of the bladder to storage. The transport is then disconnected from the unloading facilities and returned to the pipeline for refilling with natural gas.
Another patents related to CNG stations are U.S. Pat. No. 5,676,180 and U.S. Pat. No. 5,603,360 both of James Teel. None of these patents describe a compact modular high-security solution like the present invention, and there are no traces of a compact ready-to-install and high-security CNG station like the one purposed.
BRIEF SUMMARY OF THE INVENTION
For solving this challenge a modular CNG re-fuelling station is now purposed dividing the inner surface in three different areas: a measurement bridge area, a compression unit area and a control area including an electrical engine, an electrical switching panel or board and the remaining control devices.
Different risk classifications have been assigned to said three areas. In these kind of constructions, an “anti-explosion” classification is defined classifying areas in accordance with the potentiality of gas presence therein. The back side of this module, wherein the electrical engine is installed, has a discriminated classification using a particular security solution like pressurizing the cabin, sensing gas presence permanently for lowering security requirements, allowing the use of traditional engines and cheaper electrical components.
The most important area of this compact station resides on the front area. The front area of a CNG station must be, in accordance with the present regulations, a concrete bunker with a blasting roof and a labyrinthic inlet. Thus, in the case of a explosion inside said bunker, the explosion energy is propagated upwards without affecting the remaining structure. At the same time, a fire barrier is provided for avoiding its propagation.
The present invention provides a solution for preventing and correcting danger situations in CNG stations.
Firstly, danger situations are prevented by controlling the inner bunker atmosphere, installing ventilation systems at the upper part thereof, renewing the cabin air several times per hour avoiding the presence of gas, and simultaneously installing a gas detector inside the cabin which may activate fans forcing the ventilation if gas is detected. On the contrary, if fans are not driven, the machine is stopped and the alarm is activated thus preventing an explosive mixture inside the station.
This CNG station also includes a computer-control device defining an intelligent control equipment through multiple pre-programmed functions. This computer manages all equipment parameters. The cabin itself is constructed with anti-explosive features, particularly the cabin illustrated in the accompanying drawings which is made with 0.51″ thickness steel sheet, pneumatic aperture systems which can only be opened through the computer system and uses some closing devices. For example, if the compressor unit is running, the cabin door cannot be opened, and if the cabin is opened, it is not
GNC Galileo S.A.
Harrison & Egbert
Maust Timothy L.
LandOfFree
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