System and method for delivering reactive fluids to remote application sites

Abstract

Reactive fluids that react upon contact and are intended to be combined only at a site of application that is remote or not easily accessible are transported to the site by separate crescent internal gear pumps whose pump rates are governed by a control loop that uses individual mass flow rates and a common automatic controller. In preferred embodiments, a multi-lumen cable is used to convey the pump outputs individually to the application site, and an application head at the distal end of the cable both combines the individual flows and dispenses them to the site. The invention is useful for a variety of reactive systems and applications, but particularly for applying two-component epoxy linings to underground pipes.

Description

[0001] 1. Field of the Invention[0002] This invention resides in the fields of fluid transport systems for supplying multiple materials to remote locations at controlled flow rates and flow rate ratios.[0003] 2. Description of the Prior Art[0004] At many construction sites and various types of commercial operations, two or more fluids must be delivered to remote locations separately and yet at controlled flow rates or flow rate ratios. Examples of these operations are repairs of underground pipes by either applying a lining to the inner surface of a pipe or grouting a fissure in the pipe wall. Further examples are supplying liquid or fluidized materials to buildings or construction sites, such as bridges, parking structures, and building foundations, at locations that do not have direct access. Still further examples are supplying materials to mines, manholes, underground tanks or reservoirs, underseas locations, and dams. Examples of materials that must be supplied separately and i...

AI Technical Summary

Problems solved by technology

These pipes are susceptible to deterioration due to corrosion, organic growth, root infiltration, traffic loading, ground movement, and general degradation.

This degradation causes obstructions in the flow through the pipe and in some cases leads to collapse of the pipe.

A degraded sewer pipe, for example, may cause sewage to leak out and contaminate both ground water and soil formations, or it may cause ground water to infiltrate and thereby unnecessarily increase flow to a treatment plant.

Sewer pipes are very costly to replace and replacement often entails significant above-ground disruptions.

The procedure is an awkward one, since the uncured liner tube cannot be manipulated inside the pipe, and there is less than full assurance that the tube is properly placed or evenly pressurized along its entire length to achieve the desired degree of repair.

One difficulty with two-component reactive resin systems and multi-component reactive systems in general is that the various components react at a specific stoichiometric ratio, and any excess of one of the components results in the presence of unreacted material after the resin is cured.

In addition to the inefficiency of feeding material that does not react, the unreacted components are retained in the resin and degrade the quality of the lining.

In addition, the unreacted components may slowly leach out of the lining and contaminate the fluids passing through the pipe.

The problem is particularly acute when there is little or no back pressure at the distal end of the conduit.

Also, proportioning pumps have limited variability in ratio adjustment, since they are governed primarily by pump cylinder ratios.

Another difficulty with two-component reactive systems is that the flow rates of the components can vary with differences in viscosity, temperature, and other factors affecting the component densities, as well as the degree of wear on the pump and the condition of the hoses serving as conduits.

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