Patent Application
20180354206
The present invention relates to superheated air systems, and more specifically, to a mobile curing system used in the installation of low pressure Cured In Place Pipe (“CIPP”) systems.
The nation's infrastructure such as roads, bridges, and underwater pipes is aging. Many urban areas have underground pipes that have been around for more than a century, and much of the nation's infrastructure was built in the post-World War II era, which puts these systems at 50 or more years old. The emphasis since the infrastructure building boom has generally been on expansion, not replacement and upgrade. Given the age and lack of upkeep, it is not surprising that the infrastructure is often critically deteriorated. This is particularly true for underground pipes, such as water, sewage and gas lines which are difficult to inspect and whose deterioration is difficult to ascertain. Unfortunately, catastrophic pipe failure is often the first warning of the deteriorating condition of a pipe system.
Traditional methods of replacing a pipe and/or pipe sections require digging a trench to access the pipe, removal of the old pipe, putting in new pipe, and tying new pipe into existing structures. This is cumbersome and expensive. More recently, trenchless pipe repair technology has developed. These systems are advantageous insofar as they don't require extensive digging. One trenchless system is the Cured In Place Pipe (“CIPP”). An example of this comprises a fabric tube impregnated with a resin, with an empty bladder within the tube, all wrapped within a plastic sheet. In use this assembly is inserted into an existing pipe, and the bladder is filled with water. The filling bladder expands the resin-impregnated tube to fit the shape of the existing pipe. Pressure is held until the tube is solidified, typically by heating the water, or introducing a mixture of air and steam into the bladder, and a new pipe is created on the inside of the old pipe. In other variations, curing is facilitated by UV light.
While CIPP is an improvement over traditional pipe repair methods, there are still issues. Problems include less than ideal strength and corrosive resistance properties, high product weight, and short shelf life. Also, standard CIPP liner systems typically require unacceptably long cure times.
More recently, improvements in CIPP technology have given rise to a system incorporating thermoplastic with a melt/flow point of approximately 300-342° F. at approximately 5-15 psi, a cure point of approximately 330-370° F. at ambient pressure, and bonding point of approximately 372-412° F. at approximately 5-25 psi. This technology is described in U.S. Provisional Application 62/357,796, filed on Jul. 1, 2016, which is hereby incorporated by reference in its entirety, and U.S. patent application Ser. No. 15/614,852 filed on Jun. 6, 2017, which published on Jan. 4, 18 as publication US-2018-0003332-A1, and issued on as U.S. patent entitled CURED IN PLACE PIPE SYSTEM HAVING INTEGRATED THERMOPLASTIC WITH IMPROVED MELT-FLOW CHARACTERISTICS, which is also hereby incorporated by reference in its entirety. This new high temperature, low pressure curing CIPP technology overcomes the issues associated with earlier CIPP technology, and in particular the problems of pressurizing disintegrated pipes.
High temperature, low pressure curing CIPP technology, however, requires superheating air to 400° F. and beyond, which presents a new set of challenges. Superheating air requires specialized and cumbersome heating equipment, has very high energy demands, is loud, and must be precisely controlled. The hot air must be delivered according to a specific protocol with respect to parameters including ramp up time, pressure, and duration. Incorrectly superheating a CIPP system can destroy the CIPP system by overcuring where the superheated air enters the system, create catastrophic failure of the existing pipe system, damage the surrounding area, and/or injure or kill nearby workers.
As can be seen, there is a need for a system of superheating air for use in curing CIPP. It is desirable that this system is mobile, self-contained, sound insulated, cures relatively quickly, and can be controlled using a user friendly interface.
The curing system of the present invention includes a generator, low pressure high volume blower, heater, upstream sensor and control system that are housed within a vehicle such as a utility truck body, for mobilization from job site to job site. The curing system is particularly well configured for use with CIPP systems having thermoplastic with a melt/flow point of approximately 300-342° F. at approximately 5-15 psi, a cure point of approximately 330-370° F. at ambient pressure, and bonding point of approximately 372-412° F. at approximately 5-25 psi.
In use a technician inserts CIPP into a pipe requiring repair, and inputs project specifications into the curing system's control system. Examples of project specifications include diameter of CIPP, thickness of CIPP and heat conductivity of environment adjacent to pipe, and length of host pipe. The technician connects the curing system of the present invention to the upstream end of the CIPP and initiates the curing process, including the steps of evacuation of ambient air from lining system; pressurizing lining system; superheating lining system; evacuation of superheated air; and relieving pressure after liner has cooled down.
During the process, an upstream sensor and a downstream sensor measure parameters such as pressure and temperature and send this data to a control system. The control system includes algorithms that guide the process by adjusting specific parameters such as flow rate, temperature, exhaust rate, and duration, based on upstream and downstream sensor data and differentials there between.
These and other aspects of the present inventions will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.
The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
The following structure numbers shall apply to the following structures among the various FIGS.:
10—Curing system;
15—Truck;
17—Enclosure;
20—Generator;
30—Blower;
40—Heater
41—Air;
42—Heater intake;
44—Heater output;
45—Hot air inlet;
46—Pressure feedback outlet;
47—Pressure feedback return;
48—Hot air outlet;
50—Control system;
52—Display;
60—Lining system;
62—End cap;
63—Film;
64—Tubular substrate;
66—Bladder;
67—Double wall;
68—Ratcheting strap;
69—Retaining ridge;
70—Pipe;
72—Compromised portion;
74—Access;
75—Exhaust assembly;
76—Outlet;
77—Gauge;
78—Upstream sensor;
79—Downstream sensor;
80—Air duct;
82—Perforations;
84—Channel;
87—Return; and
90—Ground.
Broadly, the curing system of the present invention includes a generator, low pressure high volume blower, heater, upstream sensor and control system that are housed within a vehicle such as a utility truck body, for mobilization from job site to job site.
Referring to
Downstream from generator 20 is blower 30 which moves air 41 at a rate of approximately 0-280 cfm and a pressure of approximately 7-12 psi through heater intake 42 which is preferably a 4″-6″ duct. The preferred blower is DTLF 2.400 from Becker Pumps Corp. of Cuyahoga Falls, Ohio.
Air 41 travels through heater intake 42 to heater 40, which is capable of superheating the air to temperatures of approximately 400-470° F. The preferred heater is an inline duct heater from Osram Sylvania of Wilmington, Mass. Air leaving heater enters upstream sensor 78 which is configured to measure parameters such as heat, pressure, velocity, and so forth. After passing through sensor, air exits the truck via heater output 44, which is also preferably a 4″ duct. It should be understood that air passing from heater intake 42 through heater 40 and out to heater output 44 can pass through without being heated. By way of example, a specific CIPP system protocol may require inflation of bladder 66 using ambient temperature air until a desired pressure is reached, and then switching on heater 40 to deliver superheated air 41 to induce curing. Air 41 exits curing system 10 through heater output 44 and enters lining system 60, for example CIPP, at end cap 62.
Control system 50 includes display 52, and facilitates control, automation and monitoring of the system. It is depicted in
An example of a protocol in accordance with a method of the present invention is directed to a lining system within an approximately 18″ pipe that is approximately 200 linear feet in length. The bladder inflates with air from the curing system at a rate of approximately 20 mbar/min (0.29 psi/min) which gives 100 mbar (1.5 psi) in 5 minutes to allow the layers of the liner to slip and expand to the shape of the host pipe. After the initial inflation point is reached, the temperature is increased to approximately 200° F. and inflation rate is increased to approximately 50 mbar/min (0.73 psi/min) and pressure is checked and held every five minutes to ensure that the liner is holding pressure. This process is repeated until approximately 690 mbar (10 psi) internal pressure is reached. Once internal pressure has been achieved the temperature is ramped up to approximately 400° F. to approximately 470° F. Thermocouple sensors placed in between the liner and host pipe monitor the heat transfer rate and temperature target. Data from upstream sensor 78 and downstream sensor 79 also preferably helps guide the process. Once the melting process has had sufficient time, the heat is shut off immediately to prevent over melting the liner. The pressure is maintained at approximately 690 mbar (10 psi) until the liner temperature has cooled down to approximately 100° F. or lower. After the liner has cooled down, pressure is relieved and the ends of the liner are cut in such a way to reinstate the pipe back into service.
This protocol may be followed for other repair sites with pipes and lining systems having different lengths and diameters, although the inflation rates and final internal pressures will increase as the internal pressure increases.
Referring to
Evacuation of ambient air is preferably performed by pumping warmed air into lining system 60. Removing ambient air creates a faster rate of heat transfer. In this initial step warmed air, preferably approximately 150-250° F., and most preferably approximately 200° F., is pumped into channel 84 of lining system 60. It should be understood that at this step bladder 66 is not yet fully inflated, unlike the depiction in
After evacuation of ambient air, bladder 66 is inflated with warmed air, again preferably approximately 150-250° F., and most preferably approximately 200° F. Inflation of bladder expands tubular substrate 64 to fit snugly within pipe 70, and blocks compromised portion 72. Bladder inflation continues until the desired pressure is achieved, preferably approximately 5-15 psi.
A preferred embodiment, depicted in
Once lining system 60 is positioned and pressurized, it is ready for curing with superheated air. In a preferred method, superheated air, preferably approximately 400-470° F., is blown into air duct 80 which runs substantially the length of lining system 60. As shown in
In an alternative method an air duct isn't used, and superheated air enters at end cap 62 into bladder 66. This embodiment has the disadvantage of the curing process starting at end of lining system nearest the end cap, versus substantially simultaneous curing that is achieved using an air duct with perforations.
In an alternative embodiment, return 87 is connected at outlet 76 and returns superheated air to inline heater 40. This is depicted in
In a preferred embodiment, depicted in
End cap 62 also preferably includes pressure feedback outlet 46, which is coupled to a pressure transducer on the truck (not shown), which gives internal pressure data to the control system for interpretation by the operator and/or automated program. In a preferred embodiment pressure feedback outlet 46 and pressure transducer provide pressure data to control system 50. Also pressure feedback outlet 46 and pressure feedback return 47 may function as a pressure release system, particularly as a safety relief measure or for automatic shutdown of the system. Likewise, downstream end cap 62 preferably includes pressure feedback outlet 46, which is coupled to pressure transducer on downstream sensor 79, and provides pressure data to control system, operator and/or automated system.
In use a technician inserts CIPP into a pipe requiring repair, and inputs project specifications such as diameter of CIPP and thickness of CIPP into control system 50. The technician connects the curing system of the present invention to the upstream end of the CIPP and initiates the curing process. The curing process generally includes the steps of evacuation of ambient air from lining system; pressurizing lining system; superheating lining system; evacuation of superheated air; and relieving pressure after liner has cooled down. Upstream sensor 78 and a downstream sensor 79 take real time measurements and send these data to control system 50. The control system includes algorithms that guide the process by adjusting specific parameters such as flow rate, temperature, and exhaust rate based on upstream and downstream sensor data and differentials there between.
Specifications of certain structures and components of the present invention have been established in the process of developing and perfecting prototypes and working models. These specifications are set forth for purposes of describing an embodiment, and setting forth the best mode, but should not be construed as teaching the only possible embodiment. Rather, modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. It should be understood that all specifications, unless otherwise stated or contrary to common sense, are +/−10%, and that ranges of values set forth inherently include those values, as well as all increments between.
This application claims the benefit of U.S. Provisional Application 62/516,737, filed on Jun. 8, 2017, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62516737 | Jun 2017 | US |
